Oligonucleotides, oligonucleotide conjugate, composition, and use

Abstract

Provided is a single-stranded oligonucleotide capable of inhibiting the expression of PNPLA3 mRNA by means of an RNAi mechanism. The length of the single-stranded oligonucleotide is 16-30 nucleotides. Each nucleotide in the single-stranded oligonucleotide is independently a modified or unmodified nucleotide. At least one nucleotide is a nucleotide X, and at least one nucleotide is a fluoro-modified nucleotide. Moreover, in the 5' to 3' direction, the 13th nucleotide is a substituted alkoxy-modified nucleotide; the 14th nucleotide is a nucleotide X; and each of the 15th nucleotide and all subsequent nucleotides is independently a modified nucleotide. Also provided are a double-stranded oligonucleotide comprising the single-stranded oligonucleotide as an antisense strand, an oligonucleotide conjugate, and a pharmaceutical composition.

Description

Oligonucleotides, oligonucleotide conjugates and compositions and their uses Technical Field This disclosure relates to a single-stranded oligonucleotide, a double-stranded oligonucleotide, an oligonucleotide conjugate, a pharmaceutically acceptable salt, a pharmaceutical composition, and the uses and preparation methods thereof. Background Technology Metabolic dysfunction-associated steatohepatitis (MASH, formerly known as non-alcoholic steatohepatitis, NASH) develops from metabolic dysfunction-associated fatty liver disease (MAFLD, formerly known as non-alcoholic fatty liver disease, NAFLD). MASH patients often experience steatosis, inflammation, and liver fibrosis, and can further progress to cirrhosis. Furthermore, numerous studies have shown a strong correlation between obesity and type 2 diabetes and the development of MASH. Data indicates that the prevalence of MAFLD in the United States, where obesity rates are high, reaches 24%, with approximately 20%-30% of MAFLD patients believed to have MASH. However, significant unmet needs remain in the clinical drug development for MASH. Previous studies have found a significant association between liver fat content and the gene for the patatin-like phospholipase domain protein 3 (PNPLA3) (see, for example, Romeo et al. (2008) Nat. Genet., 40(12): 1461-1465). Studies using gene knock-in mice have shown that expression of sequence polymorphisms (rs738409, 1148M) in PNPLA3 leads to MAFLD, and the accumulation of catalytically inactivated PNPLA3 on the surface of lipid droplets is associated with the accumulation of triglycerides in the liver (Smagris et al. (2015) Hepatology, 61: 108-118). Specifically, the PNPLA3 148M mutation promotes the development of fibrosis by activating the hedgehog (Hh) signaling pathway, leading to the activation and proliferation of hepatic stellate cells and the excessive production and deposition of extracellular matrix (Chen et al. (2015) World J. Gastroenterol., 21(3): 794-802). In the drug development of oligonucleotides, including single-chain and double-chain oligonucleotides, the improvement of oligonucleotide modifications has never ceased. In single-chain oligonucleotides, such as ASO and ssRNAi, and in double-chain oligonucleotides, such as the antisense strand of siRNA, the type, location, and amount of modification can significantly affect key properties such as pharmacodynamic activity, stability, and long-lasting effect. Although numerous oligonucleotide modification schemes have been disclosed in the prior art, how to improve the modification of oligonucleotides, especially the antisense strands of single-chain and double-chain oligonucleotides, to obtain oligonucleotides with higher activity, higher stability, and / or longer-lasting effect remains a research direction in this field. Summary of the Invention The present invention provides a single-stranded oligonucleotide, a double-stranded oligonucleotide containing the single-stranded oligonucleotide of the present invention as the antisense strand, and an oligonucleotide conjugate, all of which exhibit good pharmaceutical activity and stability when targeting PNPLA3 mRNA. In one aspect, this disclosure provides a single-stranded oligonucleotide of 16-30 nucleotides in length, the composition of which enables the single-stranded oligonucleotide to inhibit the expression of PNPLA3 mRNA via an RNAi mechanism; each nucleotide in the single-stranded oligonucleotide is independently modified or unmodified, wherein at least one nucleotide in the single-stranded oligonucleotide is nucleotide X, and at least one nucleotide is a fluorinated nucleotide; furthermore, the 13th nucleotide of the single-stranded oligonucleotide is a substituted alkoxy-modified nucleotide along the 5'-3' direction; the 14th nucleotide of the single-stranded oligonucleotide is nucleotide X; and each of the 15th nucleotide and all subsequent nucleotides of the single-stranded oligonucleotide is independently modified; each nucleotide X is independently deoxyribonucleotide or unmodified nucleotide. In another aspect, this disclosure provides a double-stranded oligonucleotide containing a sense strand and an antisense strand, each nucleotide in the sense strand being a modified or unmodified nucleotide, the sense strand and the antisense strand being at least partially anticomplementary to form a double-stranded region, wherein the antisense strand is a single-stranded oligonucleotide as described in this disclosure. In another aspect, this disclosure provides a double-stranded oligonucleotide comprising a sense strand and an antisense strand, each nucleotide in the sense strand and the antisense strand being independently modified or unmodified, the sense strand and the antisense strand being at least partially anticomplementary to form a double-stranded region, wherein the unmodified equivalent sequences of the sense strand and the antisense strand are identical to the unmodified equivalent sequences of the sense strand and the antisense strand of any of the siRNAs listed in Table 1A by at least 15, at least 16, at least 17, at least 18, or 19 consecutive nucleotides, and wherein there are no more than 3 base differences, no more than 1 base difference, or no base differences. In another aspect, this disclosure also provides an oligonucleotide conjugate containing an oligonucleotide group and a delivery group conjugated to the oligonucleotide group, the oligonucleotide group being independently formed by removing one or more atoms or groups of atoms from a single-stranded or double-stranded oligonucleotide provided in this disclosure. In another aspect, this disclosure also provides pharmaceutically acceptable salts of the single-stranded oligonucleotides, double-stranded oligonucleotides, or oligonucleotide conjugates described herein. In another aspect, this disclosure also provides a pharmaceutical composition comprising one or more of the single-stranded oligonucleotides, double-stranded oligonucleotides, oligonucleotide conjugates, and pharmaceutically acceptable salts described herein, as well as pharmaceutically acceptable excipients. In another aspect, this disclosure also provides the use of one or more of the single-stranded oligonucleotides, double-stranded oligonucleotides, oligonucleotide conjugates, pharmaceutically acceptable salts, and pharmaceutical compositions of this disclosure in the preparation of a medicament for treating and / or preventing diseases or symptoms associated with PNPLA3 mRNA levels. In another aspect, this disclosure also provides a method for treating and / or preventing diseases or symptoms associated with PNPLA3 mRNA levels, the method comprising administering to a subject in need an effective amount of one or more of the single-stranded oligonucleotides, double-stranded oligonucleotides, oligonucleotide conjugates, pharmaceutically acceptable salts, and pharmaceutical compositions of this disclosure. In another aspect, this disclosure also provides a method for regulating the expression level of the PNPLA3 gene in cells, the method comprising contacting the cells with an effective amount of one or more of the single-stranded oligonucleotide, double-stranded oligonucleotide, oligonucleotide conjugate, pharmaceutically acceptable salt, and pharmaceutical composition of this disclosure. In another aspect, this disclosure also provides one or more of the single-stranded oligonucleotides, double-stranded oligonucleotides, oligonucleotide conjugates, pharmaceutically acceptable salts, and pharmaceutical compositions of this disclosure for use as pharmaceuticals. In another aspect, this disclosure also provides a cell expressing PNPLA3 mRNA, the cell comprising one or more of the single-stranded oligonucleotides, double-stranded oligonucleotides, oligonucleotide conjugates, pharmaceutically acceptable salts, and pharmaceutical compositions of this disclosure. In addition, this disclosure also provides a kit comprising one or more of the single-stranded oligonucleotides, double-stranded oligonucleotides, oligonucleotide conjugates, pharmaceutically acceptable salts, and pharmaceutical compositions of this disclosure. Incorporate by reference All publications mentioned in this specification, including patents, patent applications or non-patent documents, are incorporated herein by reference to the same extent that each individual publication is specifically and individually incorporated herein by reference. Beneficial effects Double-stranded oligonucleotides, oligonucleotide conjugates, and / or pharmaceutical compositions containing the single-stranded oligonucleotides described in this disclosure as antisense strands have high activity in regulating PNPLA3 mRNA, for example, they have good stability and PNPLA3 mRNA inhibitory activity in cells and / or in subjects, and therefore have good application prospects. On the one hand, the siRNA, conjugates, and / or pharmaceutical compositions of this disclosure containing the antisense strand exhibit excellent PNPLA3 mRNA inhibitory effects. For example, in in vitro HepG2 cells, various siRNA conjugates provided by this disclosure showed good inhibitory effects, with inhibition rates exceeding 74% at a low concentration of 50 nM, reaching a maximum of 82%; even at concentrations reduced to 5 nM and 0.5 nM, they maintained good inhibitory levels. For another example, in in vitro HepG2 cells, when the siRNA concentration was 50 nM and 5 nM, the inhibition rates of all conjugates were greater than 55%, reaching a maximum of 73.5%. For yet another example, in primary monkey liver cells, all tested conjugates showed inhibition rates exceeding 73% against PNPLA3 mRNA at a concentration of 10 nM, with some conjugates even reaching an inhibition rate of 86.4%. Even at a low concentration of 0.1 nM, some conjugates still achieved an inhibition rate of 67% against PNPLA3 mRNA. For example, in humanized PNPLA3 148M transgenic mice, siRNA concentrations of 9 mg / kg all exhibited significant inhibitory effects on PNPLA3 mRNA, with inhibition rates ranging from 81.3% to 97.1%, and most conjugates showing inhibition rates close to or exceeding 90%. Furthermore, in humanized PNPLA3 148M transgenic mice, at siRNA concentrations of 1 mg / kg, 3 mg / kg, and 9 mg / kg, all conjugates and dosage combinations showed sustained inhibitory effects over a 43-day experimental period, strongly demonstrating the potential of the conjugates to long-actingly inhibit hPNPLA3 mRNA. These results indicate that the conjugates disclosed herein possess good PNPLA3 mRNA inhibitory effects and show significant pharmaceutical activity in the preparation of drugs for the treatment and / or prevention of diseases or symptoms related to PNPLA3 mRNA expression, demonstrating excellent development prospects. Detailed Implementation The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure. In this disclosure, PNPLA3 mRNA refers to the mRNA with the sequence shown in GenBank accession number NM_025225.3 or one of MP146987.1, MP146988.1, MP146989.1, MP146990.1, MP146991.1, MP146992.1, MP146993.1, and MP146994.1. Further, unless otherwise specified, the term "PNPLA3 gene" as used in this disclosure refers to the gene that transcribes the aforementioned PNPLA3 mRNA. definition In the context of this document, the terms "complementary" and "reverse complementary" are used interchangeably and have the meaning known to those skilled in the art: in a double-stranded nucleic acid structure, each base on one strand forms a hydrogen bond with a base on the other strand in a complementary manner, achieving base pairing and forming a Watson-Crick base pair. A "base pair" refers to the two bases that form a base pair. In DNA, the purine base adenine (A) always pairs with the pyrimidine base thymine (T) (or uracil (U) in RNA); the purine base guanine (G) always pairs with the pyrimidine base cytosine (C). Each base pair consists of one purine and one pyrimidine. When adenine on one strand always pairs with thymine (or uracil) on the other strand, and guanine always pairs with cytosine, the two strands are considered complementary, and the sequence of the complementary strand can be inferred from its sequence. When bases are modified, as long as the pairing relationship of purines and pyrimidines (including but not limited to the number and strength of hydrogen bonds between bases) is not affected, the modified bases are considered to be able to form complementary pairs. Correspondingly, "mismatch" or "base mismatch" in this field means that the bases at corresponding positions between the two single-stranded nucleic acids involved are not paired in a complementary manner; when the corresponding position includes a baseless nucleotide, it is also considered to have formed a mismatch with the bases on the other strand. In the preceding and following text, "at least partially anti-complementary," "substantially anti-complementary," "truly anti-complementary," and "completely anti-complementary" refer to the base pairing between two single-stranded nucleotide sequences: between a single-stranded oligonucleotide and PNPLA3 mRNA, between a single-stranded oligonucleotide and nucleotide sequence m, between the sense and antisense strands of a double-stranded oligonucleotide, and between the antisense strand of a double-stranded oligonucleotide and PNPLA3 mRNA. Unless otherwise specified, "at least partially anti-complementary" means that within a hypothetical or actual double-stranded region, there are no more than 50% base mismatches between the two nucleotide sequences capable of forming a double-stranded region; "substantially anti-complementary" means that within a hypothetical or actual double-stranded region, there are no more than 3 base mismatches between the two nucleotide sequences capable of forming a double-stranded region; "truly anti-complementary" means that within a hypothetical or actual double-stranded region, there are no more than 1 base mismatch between the two nucleotide sequences capable of forming a double-stranded region; and "completely anti-complementary" means that within a hypothetical or actual double-stranded region, there are no base mismatches between the two nucleotide sequences capable of forming a double-stranded region. When the two nucleotide sequences are “at least partially reverse complementary,” “substantially reverse complementary,” “truly reverse complementary,” or “completely reverse complementary,” they can form a double-stranded hybrid consisting of Watson-Crick base pairs after annealing. Unless otherwise stated, when referring to a shorter nucleotide sequence as "completely anticomplementary" to a longer nucleotide sequence, it means that the two nucleotide sequences are completely anticomplementary along the entire length of the shorter nucleotide sequence. For example, the complete anticomplementary relationship between the single-stranded oligonucleotide and PNPLA3 mRNA described in this disclosure means that the single-stranded oligonucleotide is completely anticomplementary along its entire length; in other words, each nucleotide in the single-stranded oligonucleotide forms a Watson-Crick base pair with a corresponding nucleotide on the PNPLA3 mRNA to form a double-stranded hybrid. In the context of this disclosure, a "double-stranded region" is a double-stranded structure formed between the shortest nucleotide sequences comprising all base pairs on each single strand of a hypothetical or actual double-stranded nucleic acid structure. Therefore, a double-stranded region consists of all base pairs in the double-stranded nucleic acid structure and all base mismatches between those base pairs. In some embodiments, the double-stranded nucleic acid structure includes a double-stranded region and one or more overhanging ends, said overhanging ends consisting of all nucleotides outside the double-stranded region in one or both single strands of the double-stranded nucleic acid structure that do not form base pairs. In some embodiments, the double-stranded nucleic acid structure includes only a double-stranded region. The two nucleotide sequences that can form a double-stranded region can be of the same or different lengths. In some embodiments, the double-stranded nucleic acid structure includes only the double-stranded region, in which case the two nucleotide sequences forming the double-stranded nucleic acid structure are of the same length. "At least partially anticomplementary" means that there is no more than 50% base mismatch between the two nucleotide sequences; "substantially anticomplementary" means that there is no more than 3 base mismatches between the two nucleotide sequences; "substantially anticomplementary" means that there is no more than 1 base mismatch between the two nucleotide sequences; and "completely anticomplementary" means that there is no base mismatch between the two nucleotide sequences. In some embodiments, the two nucleotide sequences forming the double-stranded nucleic acid structure are of the same length, the double-stranded nucleic acid structure includes a double-stranded region and one or both overhanging ends of the longer nucleotide sequence. In some embodiments, the two nucleotide sequences forming the double-stranded nucleic acid structure are of different lengths, the double-stranded nucleic acid structure includes a double-stranded region and one or both overhanging ends of the longer nucleotide sequence. For example, in some embodiments, the sense and antisense strands of a double-stranded oligonucleotide are of different lengths. For example, the double-stranded oligonucleotide is siRNA, in which case the sense strand is usually shorter and is a shorter nucleotide sequence, while the antisense strand is longer and is the longer nucleotide sequence. The double-stranded nucleic acid structure includes a double-stranded region and a dangling end in the antisense strand. In the preceding and following text, "nucleotide sequence A and nucleotide sequence B are substantially anticomplementary, substantially anticomplementary, or completely anticomplementary across a length of X nucleotides" means that there exists a continuous nucleotide sequence A' of length X in nucleotide sequence A, which is substantially anticomplementary, substantially anticomplementary, or completely anticomplementary to a continuous nucleotide sequence B' of length X in nucleotide sequence B. In the foregoing and hereinafter, particularly in the description of methods for preparing double-stranded oligonucleotides, pharmaceutical compositions, or oligonucleotide conjugates of this disclosure, unless otherwise specified, the nucleoside monomer refers to the modified or unmodified RNA phosphoramidites (sometimes also called nucleoside phosphoramidites) used in phosphoramidite solid-phase synthesis, depending on the type and sequence of nucleotides in the desired double-stranded oligonucleotide or oligonucleotide conjugate. Phosphoramidite solid-phase synthesis is a method known to those skilled in the art for RNA synthesis. All nucleoside monomers used in this disclosure are commercially available. Unless otherwise specified, in the context of any reference to an oligonucleotide and / or oligonucleotide conjugate described in the application or method provided in this disclosure, including but not limited to any oligonucleotide and / or oligonucleotide conjugate represented by a structural formula described in the application or method provided in this disclosure, the reference also refers to a pharmaceutically acceptable salt of the oligonucleotide and / or oligonucleotide conjugate, depending on the context. Various protecting groups, such as hydroxyl or amino protecting groups, may be used in this disclosure. As stated above and below, protecting groups insensitize chemical functional groups to specific reaction conditions and can be added to and removed from such functional groups in a molecule without substantially impairing the rest of the molecule. Representative hydroxyl protecting groups are disclosed in Beaucage et al., Tetrahedron 1992, 48, 2223-2311, and Peter GMWuts, GREEN's Protective Groups in Organic Synthesis, Chapter 2, 5th edition, John Wiley & Sons Inc., New Jersey, 2014, all of which are incorporated herein by reference in their entirety. In some embodiments, the protecting group is stable under basic conditions but can be removed under acidic conditions. In some embodiments, non-exclusive examples of hydroxyl protecting groups that may be used herein include dimethoxytriphenylmethyl (DMT), monomethoxytriphenylmethyl, 9-phenyloxanthracene-9-yl (Pixyl), and 9-(p-methoxyphenyl)oxanthracene-9-yl (Mox). In some embodiments, non-exclusive examples of hydroxyl protecting groups that may be used herein include Tr (triphenylmethyl), MMTr (4-methoxytriphenylmethyl), DMTr (4,4'-dimethoxytriphenylmethyl), and TMTr (4,4',4”-trimethoxytriphenylmethyl). The term “subject” as used herein refers to any animal, such as a mammal or marsupial. Subjects in this disclosure include, but are not limited to, humans, non-human primates (e.g., rhesus monkeys or other types of macaques), mice, pigs, horses, donkeys, cattle, rabbits, sheep, rats, and any kind of poultry. In some embodiments, “subject” refers to a mammal, such as a rodent or primate. In some embodiments, “subject” refers to a mouse, rat, or non-human primate. In some embodiments, “subject” refers to a human subject. As used herein, “treatment” refers to a method of achieving a beneficial or desired outcome, including but not limited to treatment benefits. A “treatment benefit” means the eradication or improvement of the underlying disorder being treated. Furthermore, a treatment benefit is achieved by eradicating or improving one or more physical symptoms associated with the underlying disorder, thereby observing improvement in the subject, even though the subject may still be suffering from the underlying disorder. As used herein, “prevention” refers to methods for obtaining a beneficial or desired outcome, including but not limited to preventive benefits. To obtain a “preventive benefit,” the single-stranded oligonucleotide, double-stranded oligonucleotide, pharmaceutical composition, or oligonucleotide conjugate of this disclosure may be administered to a subject at risk of developing a specific disease, or to a subject reporting one or more physiological symptoms of a disease, even if a diagnosis of the disease may not have been made. In some embodiments, “prevention” includes reducing or eliminating the disease risk by intervening in the PNPLA3 mRNA or PNPLA3 protein levels in a subject at risk of developing a specific disease before the disease risk associated with PNPLA3 mRNA levels progresses to a defined disease course. The single-stranded oligonucleotides disclosed herein In one aspect, this disclosure provides a single-stranded oligonucleotide of 16-30 nucleotides in length, the composition of which enables the single-stranded oligonucleotide to inhibit the expression of PNPLA3 mRNA via an RNAi mechanism; each nucleotide in the single-stranded oligonucleotide is independently modified or unmodified, wherein at least one nucleotide in the single-stranded oligonucleotide is nucleotide X, and at least one nucleotide is a fluorinated nucleotide; furthermore, the 13th nucleotide of the single-stranded oligonucleotide is a substituted alkoxy-modified nucleotide along the 5'-3' direction; the 14th nucleotide of the single-stranded oligonucleotide is nucleotide X; and each of the 15th nucleotide and all subsequent nucleotides of the single-stranded oligonucleotide is independently modified; each nucleotide X is independently deoxyribonucleotide or unmodified nucleotide. In this disclosure, by regulating the expression level of PNPLA3 mRNA and / or altering the PNPLA3 protein level, it is possible to treat or prevent diseases related to the expression level of PNPLA3 mRNA and / or the PNPLA3 protein level. The inventors unexpectedly discovered that the single-stranded oligonucleotides described in this disclosure, the double-stranded oligonucleotides containing the single-stranded oligonucleotides described in this disclosure as antisense strands, and the oligonucleotide conjugates have good stability and PNPLA3 mRNA inhibitory activity in cells and / or in subjects, and therefore have good application prospects. To achieve RNAi activity, the single-stranded oligonucleotides described in this disclosure are 16-30 nucleotides in length. In some embodiments, the single-stranded oligonucleotides described in this disclosure are 17-28, 19-27, or 20-25 nucleotides in length. In some embodiments, the single-stranded oligonucleotides described in this disclosure are 19, 21, or 23 nucleotides in length. In these cases, the single-stranded oligonucleotides described in this disclosure, the double-stranded oligonucleotides containing the single-stranded oligonucleotide as the antisense strand, and the oligonucleotide conjugates exhibit a better balance between stability and RNAi activity. In the single-stranded oligonucleotides of this disclosure, at least one nucleotide is nucleotide X, at least one nucleotide is a fluorinated nucleotide, and, in the 5'-3' direction, the 14th nucleotide of the single-stranded oligonucleotide is nucleotide X, the 13th nucleotide of the single-stranded oligonucleotide is a substituted alkoxy-modified nucleotide, and each of the 15th nucleotide and all subsequent nucleotides of the single-stranded oligonucleotide is independently modified nucleotide. The inventors have particularly discovered that the single-stranded oligonucleotides of this disclosure, by comprising the aforementioned fluorinated nucleotide, substituted alkoxy-modified nucleotide, and nucleotide X, can effectively maintain the high inhibitory activity of double-stranded oligonucleotides and oligonucleotide conjugates against PNPLA3 mRNA while maintaining stability. In some embodiments, the number of nucleotide X is 1-3, for example, 1, 2, or 3. In some embodiments, in the single-stranded oligonucleotide, in the 5'-3' direction, the 12th and 14th nucleotides are each independently nucleotide X. In some embodiments, in the single-stranded oligonucleotide, in the 5'-3' direction, only the 14th nucleotide is nucleotide X. Each nucleotide X is independently selected from deoxyribonucleotides or unmodified nucleotides. In this context, "unmodified nucleotide" refers to an unmodified ribonucleotide (RNA), i.e., a nucleotide with an unprotected hydroxyl group (2'-OH) at the 2' position of the ribose. Accordingly, "modified nucleotide" refers to a nucleotide in which the hydroxyl group at the 2' position of the ribose is replaced by another atom or group, or refers to a nucleotide analog. In some embodiments, the 14th nucleotide or the 12th and 14th nucleotides in the single-stranded oligonucleotide are deoxyribonucleotides in the 5'-3' orientation, and each of the other nucleotides X is independently an unmodified nucleotide. In some embodiments, the 14th nucleotide in the single-stranded oligonucleotide is a deoxyribonucleotide in the 5'-3' orientation, and each of the other nucleotides is independently a modified nucleotide. In some embodiments, the number of unmodified nucleotides in the single-stranded oligonucleotide of this disclosure is no more than 5, 4, 3, 2, or 1. In some embodiments, the number of unmodified nucleotides in the single-stranded oligonucleotide is 2 or 1. In some embodiments, each of the nucleotides in the single-stranded oligonucleotide is independently modified. As previously described, in addition to nucleotide X and substituted alkoxy-modified nucleotides, the single-chain oligonucleotides of this disclosure also include fluorinated nucleotides. In some embodiments, the number of fluorinated nucleotides is 2-7. In some embodiments, with respect to the 5'-3' orientation, the fluorinated nucleotides refer to 2-5 of the 2nd, 5th, 6th, 7th, 12th, 16th, 18th, and 19th nucleotides of the single-chain oligonucleotide. In some embodiments, with respect to the 5'-3' orientation, the fluorinated nucleotides refer to 1 or 2 of the 2nd and 12th nucleotides, 1 or 2 of the 5th-7th nucleotides, and 0-2 of the 16th-19th nucleotides of the single-chain oligonucleotide. In some embodiments, with respect to the 5'-3' orientation, the fluorinated nucleotides refer to the 2nd and 6th nucleotides of the single-chain oligonucleotide. In some embodiments, with respect to the 5'-3' orientation, the fluorinated nucleotides refer to the 2nd, 6th, and 16th nucleotides of the single-chain oligonucleotide. In some embodiments, with respect to the 5'-3' orientation, the fluorinated nucleotides refer to the 2nd, 5th, 7th, 12th, and 16th nucleotides of the single-stranded oligonucleotide. In some embodiments, with respect to the 5'-3' orientation, the fluorinated nucleotides refer to the 2nd, 7th, 12th, 16th, and 19th nucleotides of the single-stranded oligonucleotide. In some embodiments, with respect to the 5'-3' orientation, the fluorinated nucleotides refer to the 2nd, 6th, 12th, 16th, and 19th nucleotides of the single-stranded oligonucleotide. In some embodiments, each modified nucleotide in the single-stranded oligonucleotide, except for the 13th and 14th nucleotides in the 5'-3' orientation and fluorinated nucleotides, is independently selected from one of alkoxy-modified nucleotides, substituted alkoxy-modified nucleotides, alkyl-modified nucleotides, substituted alkyl-modified nucleotides, amine-modified nucleotides, heat-labile nucleotides, and BNA. In some embodiments, each modified nucleotide in the single-stranded oligonucleotide, except for the 13th and 14th nucleotides in the 5'-3' orientation and fluorinated nucleotides, is independently selected from alkoxy-modified nucleotides, substituted alkoxy-modified nucleotides, or heat-labile nucleotides. In some embodiments, the number of substituted alkoxy-modified nucleotides in the single-stranded oligonucleotide does not exceed three. In some embodiments, the number of substituted alkoxy-modified nucleotides in the single-stranded oligonucleotide does not exceed two. In some embodiments, the number of substituted alkoxy-modified nucleotides in the single-stranded oligonucleotide is one. In some embodiments, the single-stranded oligonucleotide does not contain heat-labile nucleotides. In some embodiments, the number of heat-labile nucleotides does not exceed two. In some embodiments, the number of heat-labile nucleotides is one or two. In some embodiments, each modified nucleotide other than the substituted alkoxy-modified nucleotide, nucleotide X, fluorinated nucleotide, and heat-labile nucleotide is independently an alkoxy-modified nucleotide. In this context, "thermally unstable nucleotide" refers to a nucleotide with a thermally unstable modification, wherein the thermally unstable modification is a modification that lowers the thermal dissociation temperature of the oligonucleotide duplex with the modification by at least 0.5 °C compared to an oligonucleotide duplex with an unmodified nucleotide at the corresponding position. Exemplary thermally unstable modifications can be found in the specification in PCT Publication WO2018 / 098238A1.

[0236] -

[0251] The thermal instability modification described in the paragraph. In some embodiments, the heat-labile nucleotide is a type of acyclic nucleotide or heteronucleotide. Acyclic nucleotides are a class of nucleotides formed by opening the sugar ring of a nucleotide. In some embodiments, acyclic nucleotides can be unblocking nucleic acids (UNA) or glycerol nucleic acids (GNA), wherein UNA is shown in formula (15) and GNA is shown in formula (16): In formulas (15) and (16) above, R is selected from H, OH or alkoxy (O-alkyl), and Base represents a nucleic acid base, such as A, U, G, C or T. Isonucleotides are compounds formed by altering the position of a base on the ribose ring in a nucleotide. In some embodiments, an isonucleotide can be a compound formed by moving a base from the 1'-position to the 2'-position or 3'-position on the ribose ring, as shown in formula (17) or (18). In the compounds of formulas (17)-(18) above, Base represents a nucleic acid base, such as A, U, G, C or T; R is selected from H, OH, F or non-fluorinated modifications as described above. In some embodiments, the heat-labile nucleotide is selected from one of the following: GNA as shown in formula (27A), 2'-OMe abasic nucleotide as shown in formula (27B), 3'-OMe modified nucleotide as shown in formula (27C), 5'-Me modified nucleotide as shown in formula (27D), SNA as shown in formula (27E), hGNA as shown in formula (27F), hhGNA as shown in formula (27G), mGNA as shown in formula (27H), TNA as shown in formula (27I), h'GNA as shown in formula (27J), UNA as shown in formula (27K), or a hyperspacer as shown in formula (27L). In the compounds of formulas (27A)-(27L) above, Base represents a nucleic acid base, such as A, U, G, C, or T; R 27 Selected from H, OH, F, alkoxy, alkyl, or alkoxy-substituted alkyl groups. * indicates that the carbon atom is chiral, and the compound can be an R configuration, an S configuration, or a racemic mixture of R and S configurations. In some embodiments, each thermally unstable nucleotide is independently a GNA as shown in formula (27A). In some embodiments, for ease of synthesis, each alkoxy-modified nucleotide is independently a 2'-methoxy-modified nucleotide (2'-OMe), as shown in formula (8). In some embodiments, the 2'-amino-modified nucleotide (2'-NH2) is shown in formula (9). In some embodiments, the 2'-deoxynucleotide (DNA) is shown in formula (10). In equations (7) to (10) above, Base represents a nucleic acid base, such as A, U, G, C or T. In the preceding and following text, “fluorinated nucleotides,” “2’-fluorinated nucleotides,” “nucleotides in which the 2’-hydroxyl group of the ribose group is replaced by fluorine,” and “nucleotides with a 2’-fluorinated ribose group” have the same meaning, all referring to compounds in which the 2’-hydroxyl group of the nucleotide is replaced by fluorine, resulting in compounds with the structure shown in formula (7); “methoxylated nucleotides,” “2’-methoxylated nucleotides,” “nucleotides in which the 2’-hydroxyl group of the ribose group is replaced by methoxyl,” and “nucleotides with a 2’-methoxy ribose group” have the same meaning, all referring to compounds in which the 2’-hydroxyl group of the ribose group of the nucleotide is replaced by methoxyl, resulting in compounds with the structure shown in formula (8). In some embodiments, the single-stranded oligonucleotides of this disclosure are 19-23 nucleotides in length, and in a 5'-3' orientation, the 13th nucleotide is a substituted alkoxy-modified nucleotide, the 14th nucleotide is nucleotide X, one of the 5th-7th nucleotides, and the 2nd and 16th nucleotides are fluorinated nucleotides, the 3rd nucleotide is an alkoxy-modified nucleotide or a substituted alkoxy-modified nucleotide, the 5th nucleotide is a fluorinated nucleotide, an alkoxy-modified nucleotide, or a substituted alkoxy-modified nucleotide, and each of the remaining nucleotides in the single-stranded oligonucleotide is independently an alkoxy-modified nucleotide. In some embodiments, the single-stranded oligonucleotide of this disclosure is 21 nucleotides in length, and in a 5'-3' orientation, the 13th nucleotide is a substituted alkoxy-modified nucleotide, the 14th nucleotide is nucleotide X, the 2nd, 6th and 16th nucleotides are fluorinated nucleotides, the 3rd or 5th nucleotide is an alkoxy-modified nucleotide or a substituted alkoxy-modified nucleotide, and each of the remaining nucleotides in the single-stranded oligonucleotide is independently an alkoxy-modified nucleotide. BNA refers to a restricted or inaccessible nucleotide. BNA can contain a bridging structure with a "fixed" C3'-endoglucan condensation, consisting of a five-membered, six-membered, or seven-membered ring. This bridge is typically incorporated into the 2'-, 4'-position of the ribose to provide a 2', 4'-BNA nucleotide. In some embodiments, BNA can be LNA, ENA, cET BNA, etc., where LNA is shown in formula (12), ENA in formula (13), and cET BNA in formula (14). In the compounds of formulas (7)-(10) and (12)-(14) above, Base represents a nucleic acid base, such as A, U, G, C or T. In some embodiments, each nucleotide X in the single-chain oligonucleotides of this disclosure refers to a deoxynucleotide. Each alkoxy-modified nucleotide refers to a methoxy-modified nucleotide. In some embodiments, each substituted alkoxy-modified nucleotide in the single-chain oligonucleotides of this disclosure refers to a 2'-O-methoxyethyl-modified nucleotide. In some embodiments, each BNA in the single-chain oligonucleotides of this disclosure refers to an LNA or cET BNA. In some embodiments, each heat-labile nucleotide in the single-chain oligonucleotides of this disclosure refers to a GNA. In some embodiments, each of at least two linking groups between adjacent nucleotides in the single-stranded oligonucleotide is independently a phosphate ester group with a modifying group. In some embodiments, in the single-stranded oligonucleotide of this disclosure, each of one to four linking groups between adjacent nucleotides in the 1st to 5th nucleotides at the 5' end is independently a phosphate ester group with a modifying group. In some embodiments, in the single-stranded oligonucleotide of this disclosure, each of one to four linking groups between adjacent nucleotides in the 1st to 5th nucleotides at the 3' end is independently a phosphate ester group with a modifying group. In some embodiments, in the single-stranded oligonucleotide of this disclosure, two linking groups or four linking groups between adjacent nucleotides in the 1st to 3rd nucleotides at the 5' end are phosphate ester groups with modifying groups. In some embodiments, in the single-stranded oligonucleotide of this disclosure, two linking groups or four linking groups between adjacent nucleotides in the 1st to 3rd nucleotides at the 3' end are phosphate ester groups with modifying groups. In some embodiments, in the single-stranded oligonucleotides of this disclosure, if unmodified nucleotides are present in the single-stranded oligonucleotide, each of the two linking groups between each unmodified nucleotide and its adjacent nucleotide is independently a phosphate ester group with a modifying group. The modified phosphate ester group can make the single-stranded oligonucleotides of this disclosure more resistant to the action of exonucleases, enhancing the stability of the oligonucleotide in the subject's body. In some embodiments, each of the 2-6 linking groups between adjacent nucleotides in the single-stranded oligonucleotide is independently a phosphate ester group with a modifying group. In some embodiments, each of the 3 or 4 linking groups between adjacent nucleotides in the single-stranded oligonucleotide is independently a phosphate ester group with a modifying group. In some embodiments, each of the linking groups between adjacent nucleotides in the 1st-3rd nucleotides at the 5' end and between adjacent nucleotides in the 1st-3rd nucleotides at the 3' end of the single-stranded oligonucleotide is independently a phosphate ester group with a modifying group. In some embodiments, if unmodified nucleotides are present in the single-stranded oligonucleotide, each of one or both of the two linking groups between each unmodified nucleotide and its adjacent nucleotide is independently a phosphate group with a modifying group. In some embodiments, each phosphate group with a modifying group is independently a thiophosphate group having the structure shown in formula (28): In some embodiments, the 5'-terminal nucleotide of the single-stranded oligonucleotide is a 5'-hydroxynucleotide, a 5'-phosphate nucleotide, or a 5'-phosphate analog-modified nucleotide, wherein the 5'-hydroxynucleotide has the structure shown in formula (29); the 5'-phosphate nucleotide has the structure shown in formula (30); and the 5'-phosphate analog-modified nucleotide has a structure selected from those shown in formulas (31) to (34). R is selected from H, OH, OCH3 and F; Base represents a nucleic acid base, selected from A, U, C, G or T. In some embodiments, the 5'-phosphate nucleotide is a nucleotide containing a 5'-phosphate modification as shown in formula (30), the 5'-phosphate analog modified nucleotide is a nucleotide containing a vinyl phosphate (5'-(E)-vinylphosphonate, E-VP) modification as shown in formula (31), or a phosphate thioester modified nucleotide as shown in formula (33). In some embodiments, the 5'-terminal nucleotide of the single-stranded oligonucleotide is a 5'-hydroxy nucleotide or a nucleotide containing a vinyl phosphate (5'-(E)-vinylphosphonate, E-VP) modification. In some embodiments, the 5'-terminal nucleotide being a vinyl phosphate (5'-(E)-vinylphosphonate, E-VP) modified nucleotide can further increase one or more of the stability, in vivo pharmacodynamic activity, and long-lasting effect of the single-stranded oligonucleotide, double-stranded oligonucleotide containing the single-stranded oligonucleotide, and oligonucleotide conjugates described herein. As previously described, the composition of the single-chain oligonucleotides disclosed herein enables them to inhibit the expression of PNPLA3 mRNA via an RNAi mechanism. In some embodiments, the single-chain oligonucleotides disclosed herein are sufficiently complementary to PNPLA3 mRNA. In the context of this disclosure, "sufficiently complementary" means that the complementarity between the single-chain oligonucleotides disclosed herein and PNPLA3 mRNA is sufficient to reduce or eliminate the production of the protein encoded by the PNPLA3 mRNA through RNAi. In some embodiments, "sufficiently complementary" means that the single-chain oligonucleotides disclosed herein are substantially anticomplementary, substantially anticomplementary, or completely anticomplementary to PNPLA3 mRNA across at least 16 nucleotides, for example, across 16-25 nucleotides, across 18-23 nucleotides, or across 19-21 nucleotides. In some embodiments, the single-chain oligonucleotides disclosed herein are completely anticomplementary to PNPLA3 mRNA. In some embodiments, the two "fully complementary" nucleotide sequences may include completely anticomplementary internal regions (e.g., completely anticomplementary across a length of at least 6, 8, or 10 nucleotides). In some embodiments, the single-stranded oligonucleotide of this disclosure is completely anticomplementary to PNPLA3 mRNA at least within a seed region. The "seed region" refers to the region of nucleotides 2-8 of the single-stranded oligonucleotide of this disclosure, where the single-stranded oligonucleotide of this disclosure can better mediate RNAi action and suppress PNPLA3 mRNA levels. In some embodiments, the single-stranded oligonucleotide is substantially anticomplementary or completely anticomplementary to PNPLA3 mRNA across a length of at least 16 nucleotides. In some embodiments, the nucleotide sequence of the single-stranded oligonucleotide from position 2 to 19, in the 5'-3' direction, is completely anticomplementary to PNPLA3 mRNA. In some embodiments, the nucleotide sequence of the single-stranded oligonucleotide other than position 1 at the 5' end, in the 5'-3' direction, is completely anticomplementary to PNPLA3 mRNA. In some embodiments, all nucleotides of the single-stranded oligonucleotide are completely anticomplementary to PNPLA3 mRNA. In some embodiments, the single-stranded oligonucleotide is substantially anticomplementary, substantially anticomplementary, or completely anticomplementary to a continuous nucleotide sequence m in PNPLA3 mRNA; the length of the nucleotide sequence m is not greater than the length of the single-stranded oligonucleotide, and the length of the nucleotide sequence m is the same as, differs from, the length of the single-stranded oligonucleotide by no more than 8 nucleotides, or differs by 1-5 nucleotides. In some embodiments, the length of the nucleotide sequence m is at least 16 nucleotides, or 16-25 nucleotides, or 18-23 nucleotides, or 19-21 nucleotides. In some embodiments, the length of the single-stranded oligonucleotide is the same as the nucleotide sequence m, and at least the nucleotide sequence other than the terminal nucleotide of the single-stranded oligonucleotide is completely anticomplementary to the nucleotide sequence m, thus, the single-stranded oligonucleotide of this disclosure can further improve the inhibitory effect on PNPLA3 mRNA. In some embodiments, the nucleotide sequence other than the first position of the single-stranded oligonucleotide is completely anticomplementary to the nucleotide sequence m in the 5'-3' direction. In some embodiments, all nucleotides of the single-stranded oligonucleotide are completely anticomplementary to the nucleotide sequence m. In some embodiments, the single-stranded oligonucleotide of this disclosure is substantially anticomplementary, substantially anticomplementary, or completely anticomplementary to at least 15, 16, 17, 18, or 19 consecutive nucleotides of any one of the sequences shown in Table 1A below (SEQ ID NO:1-SEQ ID NO:8). In some embodiments, the unmodified equivalent sequence of the single-stranded oligonucleotide has at least 17, 18, 19, 20, or 21 consecutive identical nucleotides of any one of the nucleotide sequences shown in Table 1A (SEQ ID NO:9-SEQ ID NO:16 and SEQ ID NO:67), and the consecutive identical nucleotides include no more than 3 base differences, no more than 1 base difference, or no base differences. In some embodiments, at least the 2nd to 19th nucleotides of the unmodified equivalent sequence of the single-stranded oligonucleotide, in the 5'-3' direction, have a base difference of no more than one or no base difference between the 2nd to 19th nucleotides of the nucleotide sequences shown in any one of SEQ ID NO:9-SEQ ID NO:16 and SEQ ID NO:67. In some embodiments, the single-stranded oligonucleotide contains nucleotide sequence II, which is identical to at least 16, 17, 18, 19, 20, or 21 consecutive nucleotides of any one of the nucleotide sequences shown in SEQ ID NO:9-SEQ ID NO:16 and SEQ ID NO:67 in Table 1A, and the identical nucleotides include a base difference of no more than three. In some embodiments, the single-stranded oligonucleotide contains nucleotide sequence II, which has a base difference of no more than one or no base difference between the 1st to 19th nucleotides of the nucleotide sequences shown in any one of SEQ ID NO:9-SEQ ID NO:16 and SEQ ID NO:67 in Table 1A. In some embodiments, the nucleotide sequence II described herein is any one of SEQ ID NO:9-SEQ ID NO:16 and SEQ ID NO:67 listed in Table 1A. In some embodiments, the single-stranded oligonucleotide further comprises a nucleotide sequence IV linked to the 3' end of nucleotide sequence II, the nucleotide sequence IV being one, two, three, or four nucleotides in length, each nucleotide in nucleotide sequence IV being independently one of a non-fluorinated modified nucleotide, the nucleotide sequence IV being substantially anticomplementary or completely anticomplementary to PNPLA3 mRNA, and each of the non-fluorinated modified nucleotides being independently selected from one of a 2'-methoxy modified nucleotide, a 2'-alkyl modified nucleotide having 1-3 carbon atoms, a 2'-amino modified nucleotide, a 2'-substituted amino modified nucleotide, and a heat-labile nucleotide. In some embodiments, the length of the nucleotide sequence IV is 2 nucleotides. In some embodiments, the single-stranded oligonucleotide further comprises a nucleotide sequence V, each nucleotide of the nucleotide sequence V being an independent non-fluorinated nucleotide, the nucleotide sequence V being 1 to 3 nucleotides in length and attached to the 3' end of the nucleotide sequence IV or nucleotide sequence II, wherein the nucleotide sequence V constitutes the 3' overhang of the double-stranded oligonucleotide after the single-stranded oligonucleotide is combined with the sense strand. In some embodiments, the nucleotide sequence V is 2 nucleotides in length and, in a 5'-3' orientation, is two consecutive thymine deoxynucleotides, two consecutive uracil nucleotides, or is completely reverse complementary to PNPLA3 mRNA. In some embodiments, the single-stranded oligonucleotide is the antisense strand shown in SEQ ID NO:52, SEQ ID NO:54, SEQ ID NO:56, SEQ ID NO:58, SEQ ID NO:60, SEQ ID NO:62, SEQ ID NO:64, SEQ ID NO:66, or SEQ ID NO:68 listed in Table 1B. In some embodiments, the single-stranded oligonucleotide is the antisense strand shown in SEQ ID NO:18, SEQ ID NO:20, SEQ ID NO:22, SEQ ID NO:24, SEQ ID NO:26, SEQ ID NO:28, SEQ ID NO:30, SEQ ID NO:32, SEQ ID NO:34, SEQ ID NO:36, SEQ ID NO:38, SEQ ID NO:40, or SEQ ID NO:42 listed in Table 2. Table 1A Unmodified double-stranded oligonucleotide sequences In some embodiments, the single-chain oligonucleotides of this disclosure can exert pharmacological activity independently. In some embodiments, the single-chain oligonucleotides of this disclosure are antisense oligonucleotides (ASO). In some embodiments, the single-chain oligonucleotides of this disclosure are single-chain RNAi (ssRNAi) compounds. In some embodiments, the single-chain oligonucleotides of this disclosure exert pharmacological activity as a single strand (e.g., antisense strand) of a double-chain oligonucleotide. The double-stranded oligonucleotides disclosed herein In another aspect, this disclosure also provides a double-stranded oligonucleotide containing a sense strand and an antisense strand, each nucleotide in the sense strand being a modified or unmodified nucleotide, the sense strand and the antisense strand being at least partially anticomplementary to form a double-stranded region, wherein the antisense strand is a single-stranded oligonucleotide as described above in this disclosure. In the double-stranded oligonucleotides of this disclosure, the length of the sense strand and the antisense strand is each 19-26 nucleotides. In some embodiments, the length difference between the sense strand and the antisense strand is 0-5 nucleotides. In some embodiments, the length of the sense strand is not greater than the length of the antisense strand. In some embodiments, the length of the sense strand is 19-23 nucleotides. Therefore, the length ratio of the sense strand to the antisense strand in the double-stranded oligonucleotides of this disclosure can be 19 / 19, 19 / 20, 19 / 21, 19 / 22, 20 / 20, 20 / 21, 20 / 22, 20 / 23, 21 / 21, 21 / 22, 21 / 23, 21 / 24, 22 / 22, 22 / 23, 22 / 24, 22 / 25, 23 / 23, 23 / 24, 23 / 25, or 23 / 26. In some embodiments, the length of the sense strand is 15-26 or 17-24 nucleotides. In some embodiments, the length of the sense strand is 19-21 nucleotides. In some embodiments, for ease of synthesis, the length of the sense strand is 19-21 nucleotides, and the length of the antisense strand is 19-23 nucleotides. In some embodiments, the lengths of the sense strand and antisense strand are the same, both being 19, 20, or 21 nucleotides. In some embodiments, the length of the sense strand is 19-21 nucleotides, and the length of the antisense strand is 20-24 nucleotides, with the antisense strand being 1-3 nucleotides longer than the sense strand. In some embodiments, the length of the antisense strand is 2 nucleotides longer than the sense strand. In some embodiments, the length of the sense strand is 19 nucleotides, and the length of the antisense strand is 21 nucleotides; or the length of the sense strand is 21 nucleotides, and the length of the antisense strand is 21 nucleotides; or the length of the sense strand is 21 nucleotides, and the length of the antisense strand is 23 nucleotides. In some embodiments, the length of the sense strand is 19 nucleotides, and the length of the antisense strand is 21 nucleotides. In some embodiments, the sense strand is 21 nucleotides long and the antisense strand is 23 nucleotides long. In some embodiments, in the positive strand of the double-stranded oligonucleotide of this disclosure, 2-3 of the 11th-13th nucleotides of the positive strand, in the 3'-5' direction, are fluorinated nucleotides, and the first nucleotide of the positive strand is an alkoxylated nucleotide or an inverted abasic deoxyribonucleotide (abbreviated as invab or ia, having the structure shown in formula (35)). In some embodiments, in the 3'-5' direction, the last nucleotide of the positive strand is an alkoxylated nucleotide or an inverted abasic deoxyribonucleotide. In some embodiments, apart from the above-mentioned fluorinated and inverted abasic deoxyribonucleotides, the nucleotides at the remaining positions in the positive strand are each independently non-fluorinated nucleotides, and each non-fluorinated nucleotide is independently selected from one of alkoxylated nucleotides, alkylated nucleotides, amine-modified nucleotides, and thermally unstable nucleotides. In some embodiments, the oxygen atom directly attached to the ribose ring as shown in formula (35) may be attached to the 3' phosphate group of the penultimate nucleotide of the positive strand. In some embodiments, the oxygen atom directly attached to the ribose ring as shown in formula (35) may be attached to the 3' phosphate group of the 3' terminal nucleotide of the positive strand, and the oxygen atom attached to the ribose ring via a methylene group as shown in formula (35) may be attached to a hydrogen atom, a hydroxyl protecting group, or a delivery group as described below. In some embodiments, the oxygen atom of formula (35) connected to the ribose ring via a methylene group may be attached to the 5' phosphate group of the penultimate nucleotide at the 5' end of the positive strand. In some embodiments, the oxygen atom of formula (35) connected to the ribose ring via a methylene group may be attached to the 5' phosphate group of the penultimate nucleotide at the 5' end of the positive strand, and the oxygen atom of formula (35) directly attached to the ribose ring may be attached to a hydrogen atom, a hydroxyl protecting group, or a delivery group as described below. In some embodiments, the sense strand contains 19-21 nucleotides, and the antisense strand contains 21-23 nucleotides. In some embodiments, the 11th and 13th nucleotides, or nucleotides 11-13, of the sense strand in the 3'-5' orientation are fluorinated nucleotides, the first nucleotide and / or the last nucleotide of the sense strand is a methoxylated nucleotide or a reverse debased deoxynucleotide, and the nucleotides at the remaining positions are each independently alkoxylated nucleotides. In some embodiments, in the positive strand, at least one of the linking groups connecting two adjacent nucleotides is independently a phosphate group with a modifying group, said phosphate group with a modifying group being present at least once between two adjacent nucleotides in the first to fifth nucleotides at the 5' end of the positive strand and between two adjacent nucleotides in the first to fifth nucleotides at the 3' end. In some embodiments, each of 1-4 linking groups between any two adjacent nucleotides in the first to fifth nucleotides at the 5' end of the positive strand, and / or each of 1-4 linking groups between any two adjacent nucleotides in the first to fifth nucleotides at the 3' end of the positive strand, is independently a phosphate group with a modifying group. In some embodiments, each of all four linking groups between adjacent nucleotides in the first to fifth nucleotides at the 5' end of the positive strand is independently a phosphate group with a modifying group. In some embodiments, each of all four linking groups between adjacent nucleotides in the first to fifth nucleotides at the 3' end of the positive strand is independently a phosphate group with a modifying group. In some embodiments, the linking group connecting two adjacent nucleotides in the 1-3, 1-4, or 1-5th nucleotides at the 5' and / or 3' ends of the sense strand is a phosphate ester group with a modifying group. The definition and selection range of the phosphate ester group with a modifying group are the same as those described above for the antisense strand of this disclosure. In some embodiments, each phosphate ester group with a modifying group is independently a thiophosphate ester group having the structure shown in formula (28). In some embodiments, the chain of justice is the chain of justice shown in SEQ ID NO:51, SEQ ID NO:53, SEQ ID NO:55, SEQ ID NO:57, SEQ ID NO:59, SEQ ID NO:61, SEQ ID NO:63, or SEQ ID NO:65 listed in Table 1B. In some embodiments, the chain of justice is the chain of justice shown in SEQ ID NO:17, SEQ ID NO:19, SEQ ID NO:21, SEQ ID NO:23, SEQ ID NO:25, SEQ ID NO:27, SEQ ID NO:29, SEQ ID NO:31, SEQ ID NO:33, SEQ ID NO:35, SEQ ID NO:37, SEQ ID NO:39, or SEQ ID NO:41 listed in Table 2. In some embodiments, the sense strand comprises 19-21 nucleotides, and the antisense strand comprises 21-23 nucleotides; in the 3'-5' direction, the 11th and 13th nucleotides, or the 11th-13th nucleotides, of the sense strand are fluorinated nucleotides; the first and / or last nucleotide of the sense strand is a methoxylated nucleotide or a reverse debased deoxynucleotide; and the remaining nucleotides are each independently methoxylated nucleotides; each of 1-4 linking groups between adjacent nucleotides in the 1st-5th nucleotides at the 5' end of the sense strand, and / or each of 1-4 linking groups between adjacent nucleotides in the 1st-5th nucleotides at the 3' end of the sense strand, is independently a thiophosphate group. In some embodiments, the linking group between every two adjacent nucleotides in the 1st-2nd, 1st-3rd, 1st-4th, or 1st-5th nucleotides at the 5' end and / or 3' end of the sense strand is a thiophosphate group, and the linking groups between the remaining adjacent nucleotides in the sense strand are phosphate groups. In some embodiments, the linker between any two adjacent nucleotides in the 1st-3rd, 1st-4th, or 1st-5th nucleotides at the 5' end of the positive strand is a phosphate ester group, and the linker between the remaining adjacent nucleotides in the positive strand is a phosphate ester group. In some embodiments, the linker between any two adjacent nucleotides in the 1st-2nd, 1st-3rd, 1st-4th, or 1st-5th nucleotides at the 3' end of the positive strand is a phosphate ester group, and the linker between the remaining adjacent nucleotides in the positive strand is a phosphate ester group. In some embodiments, the double-stranded oligonucleotide of this disclosure comprises a sense strand containing 19 nucleotides and an antisense strand containing 21 nucleotides. In the sense strand, the 11th and 13th nucleotides, or the 11th to 13th nucleotides, are fluorinated nucleotides in the 3'-5' direction; the 1st and / or the last nucleotide is a reverse debased deoxynucleotide; and the remaining nucleotides are each independently methoxylated nucleotides. In the sense strand, 1-4 of the linking groups between adjacent nucleotides in the 1st to 5th nucleotides at the 5' end, and / or 1-4 of the linking groups between adjacent nucleotides in the 1st to 5th nucleotides at the 3' end, are each independently a phosphate thioate group. In some embodiments, in the antisense strand, the 13th nucleotide is a 2'-O-methoxyethyl nucleotide in the 5'-3' direction; the 14th nucleotide is a deoxynucleotide; and the 2nd, 6th, and 16th nucleotides are fluorinated nucleotides. Each of the remaining nucleotides in the antisense strand is independently alkoxylated nucleotide. In some embodiments, each ribose 2'-alkoxy modified nucleotide is a ribose 2'-C1-C3 alkoxy modified nucleotide, such as a ribose 2'-methoxy modified nucleotide. In some embodiments, each ribose 2'-substituted alkoxy modified nucleotide is independently a ribose 2'-C1-C3 alkoxy modified nucleotide with substituents, each substituent being independently selected from C1-C3 alkoxy groups. In some embodiments, each ribose 2'-alkoxy modified nucleotide refers to a ribose modified nucleotide. In some embodiments, each ribose 2'-substituted alkoxy modified nucleotide refers to a 2'-O-methoxyethyl (MOE) modified nucleotide. In some embodiments, each BNA refers to an LNA or cET BNA. In some embodiments, the linking groups between two adjacent nucleotides in the first to third nucleotides at the 5' end and between two adjacent nucleotides in the first to third nucleotides at the 3' end are phosphate groups with modifying groups, and if unmodified nucleotides are present, each of 1 to 2 of the 2 linking groups between each unmodified nucleotide and its adjacent nucleotides is independently a phosphate group with a modifying group. In some embodiments, the 5'-terminal nucleotide of the antisense chain is a 5'-hydroxy nucleotide of formula (29) or a 5'-vinyl phosphate-modified nucleotide of formula (31). The double-stranded oligonucleotides disclosed herein, through the aforementioned modification schemes, achieve a good balance between gene expression regulatory activity and in vivo stability. In the context of this disclosure, "modification scheme" refers to a combination of nucleotide ribose modifications, phosphate modifications, 5' end modifications, and / or base modifications of different numbers, positions, and types that are unrelated to or weakly related to a specific sequence. In some embodiments, the double-stranded oligonucleotides of this disclosure, through the aforementioned modification schemes, can maintain excellent stability without significantly reducing the original drug activity of the double-stranded oligonucleotide, thereby achieving a good balance between gene expression regulatory activity and in vivo stability. In some embodiments, the double-stranded oligonucleotides of this disclosure are siRNAs. The double-stranded oligonucleotides of this disclosure, through the aforementioned modification schemes, can maintain excellent stability without significantly reducing the original RNAi activity of the siRNA, thereby achieving a good balance between PNPLA3 mRNA inhibitory activity and in vivo stability. In some embodiments, the double-stranded oligonucleotide of this disclosure comprises a substantially anticomplementary or completely anticomplementary double-stranded region, and one or two dangling ends of the sense strand and / or one or two dangling ends of the antisense strand. In some embodiments, the double-stranded oligonucleotide of this disclosure comprises a substantially anticomplementary or completely anticomplementary double-stranded region and one dangling end of the antisense strand. In some embodiments, the length of the double-stranded region formed by the sense and antisense strands is at least 16 nucleotides. In some embodiments, the length of the double-stranded region formed by the sense and antisense strands is 16-23 nucleotides. In some embodiments, the length of the double-stranded region formed by the sense and antisense strands is 18, 19, 20, or 21 nucleotides. In the context of this disclosure, a "double-stranded region" is a double-stranded structure formed between the shortest nucleotide sequences comprising all base pairs on each of the single strands of a double-stranded nucleic acid structure. Therefore, a double-stranded region consists of all base pairs in the double-stranded nucleic acid structure and all base mismatches between those base pairs. In some embodiments, the number of base mismatches does not exceed 20%, 15%, 10%, or 5% of the total number of base pairs forming the double-stranded region. In some embodiments, the number of base mismatches in the double-stranded region does not exceed 3, 2, or 1. In some embodiments, the double-stranded nucleic acid structure includes a double-stranded region and one or more overhanging ends consisting of nucleotides that have not formed base pairs on one or both single strands. In some embodiments, the double-stranded nucleic acid structure includes only a double-stranded region. In some embodiments, the sense and antisense strands form a double-stranded region spanning at least 16 nucleotide positions, i.e., the double-stranded region formed by the sense and antisense strands contains at least 16 base pairs. In the context of this disclosure, each base pair forming the double-stranded region is independently complementary or mismatched. In some embodiments, the sense and antisense strands form a double-stranded region spanning 16-23 nucleotide positions, i.e., the double-stranded region formed by the sense and antisense strands contains 16-23 base pairs. In some embodiments, the sense and antisense strands form a double-stranded region spanning 18, 19, 20, or 21 nucleotide positions, i.e., the double-stranded region formed by the sense and antisense strands contains 18, 19, 20, or 21 base pairs. In some embodiments, the sense and antisense strands are substantially anticomplementary or completely anticomplementary within the double-stranded region. In some embodiments, the sense and antisense strands of the double-stranded oligonucleotides of this disclosure are substantially anticomplementary or completely anticomplementary over their entire nucleotide length. In some embodiments, the sense strand and the antisense strand are substantially anticomplementary, substantially anticomplementary, or completely anticomplementary. In some embodiments, the sense strand and the antisense strand are substantially anticomplementary or completely anticomplementary within the double-stranded region. In some embodiments, along the 5'-3' direction, at least the nucleotide sequence of the sense strand other than the first and last positions is substantially anticomplementary or completely anticomplementary to the antisense strand. In some embodiments, along the 5'-3' direction, the nucleotide sequence of the sense strand other than the last position is completely anticomplementary to the antisense strand; or all nucleotides of the sense strand are completely anticomplementary to the antisense strand. In some embodiments, the double-stranded oligonucleotides described in this disclosure include an unmodified equivalent sequence of the positive strand comprising a nucleotide sequence of the same length as nucleotide sequence m, and differing by no more than 3 bases, no more than 1 base, or having no base difference. The definition and selection of nucleotide sequence m are as described above. In the preceding and following text, "unmodified equivalent sequence" refers to an oligonucleotide sequence that, compared to the original sequence used as the basis for alignment, does not contain any ribocycle modifications, base modifications, or phosphate backbone modifications. For example, the unmodified equivalent sequence of VPAmsCfsdTGmsUmia is ACUGUN, where N is A, C, G, or U. In the preceding and following text, a "base difference" between one nucleotide sequence and another means that, compared to the latter, the type of base at the same position of the nucleotide has changed. For example, if a nucleotide base in the latter is A, and the corresponding nucleotide base at the same position in the former is U, C, G, or T, then a base difference is considered to exist between the two nucleotide sequences at that position. When bases are modified, as long as the purine-pyrimidine pairing relationship in forming the aforementioned double-stranded nucleic acid structure is not affected, it is considered that there is no base difference between the modified base and the original base. In some embodiments, it is considered that there is no base difference between U and T. In some embodiments, it is considered that there is no base difference between C and 5-methylcytosine (5mC). In some embodiments, when a baseless nucleotide or its equivalent is replaced with a nucleotide at the original position, it is also considered that a base difference has occurred at that position. When comparing two nucleotide sequences to determine the number of base differences, alignment is performed in the manner with the fewest base differences among all alignment methods, and the base differences are determined based on this alignment method. In this case, "identical position" refers to the corresponding position between the two nucleotide sequences in this alignment method. For example, when positions 1-5 of nucleotide sequence A are aligned with positions 2-6 of nucleotide sequence B in the same direction, the number of base differences is the fewest compared to other alignment methods. Therefore, "same position" means that position 1 of nucleotide sequence A is aligned with position 2 of nucleotide sequence B, position 2 of nucleotide sequence A is aligned with position 3 of nucleotide sequence B, and so on. In the preceding and following text, "unmodified equivalent sequence" refers to an oligonucleotide sequence that does not contain any ribose ring modifications, base modifications, or phosphate backbone modifications compared to the original sequence used as the basis for alignment. For example, the unmodified equivalent sequence of VPAmsCfsdTGmsUmia is ACUGUN, where N is A, C, G, or U. In some embodiments, the number of base differences between two nucleotide sequences of different lengths refers to the number of base differences calculated from the first nucleotide without a base difference to the last nucleotide without a base difference in the alignment with the minimum number of base differences. In some embodiments, the number of base differences between two nucleotide sequences of the same length refers to the total number of base differences between the first to last nucleotides of one nucleotide sequence and the first to last nucleotides of the other nucleotide sequence, in the same direction. In some embodiments, the absence of base differences between two nucleotide sequences of different lengths means that, in the same direction, there are no base differences between the first to last nucleotides of the shorter nucleotide sequence and each nucleotide at the same position in the other nucleotide sequence. In some embodiments, the absence of base differences between two nucleotide sequences of the same length means that, in the same direction, there are no base differences between the first to last nucleotides of one nucleotide sequence and the first to last nucleotides of the other nucleotide sequence. The double-stranded oligonucleotide disclosed herein can be any double-stranded oligonucleotide that regulates PNPLA3 gene expression. In some embodiments, it can be a double-stranded oligonucleotide that inhibits or downregulates PNPLA3 gene expression, such as siRNA; in some embodiments, it can be a double-stranded oligonucleotide that activates or upregulates PNPLA3 gene expression, for example, saRNA. In some embodiments, the double-stranded oligonucleotide is siRNA. In some embodiments, the sense strand contains nucleotide sequence I, and the antisense strand contains nucleotide sequence II. Sequence I is identical to any one of the nucleotide sequences shown in SEQ ID NO:1-SEQ ID NO:8 in Table 1A for at least 16, 17, 18, 19, 20, or 21 consecutive nucleotides, with no more than 3 base differences. Sequence II is identical to any one of the nucleotide sequences shown in SEQ ID NO:9-SEQ ID NO:16 and SEQ ID NO:67 in Table 1A for at least 16, 17, 18, 19, 20, or 21 consecutive nucleotides, with no more than 3 base differences. In some embodiments, the nucleotide sequence I differs from the nucleotide sequences shown in SEQ ID NO:1-8 by no more than one base, and the nucleotide sequence II differs from the first to the nineteenth bases of the nucleotide sequences shown in SEQ ID NO:9-16 and SEQ ID NO:67 by no more than one base. In some embodiments, the unmodified equivalent sequence of the double-stranded oligonucleotide is any one of siRNA1-siRNA9 in Table 1A, wherein the sense strand of siRNA1 is the sequence shown in SEQ ID NO:1 and the antisense strand is the sequence shown in SEQ ID NO:2; the sense strand of siRNA2 is the sequence shown in SEQ ID NO:3 and the antisense strand is the sequence shown in SEQ ID NO:4; the sense strand of siRNA3 is the sequence shown in SEQ ID NO:5 and the antisense strand is the sequence shown in SEQ ID NO:6; the sense strand of siRNA4 is the sequence shown in SEQ ID NO:7 and the antisense strand is the sequence shown in SEQ ID NO:8; the sense strand of siRNA5 is the sequence shown in SEQ ID NO:9 and the antisense strand is the sequence shown in SEQ ID NO:10; the sense strand of siRNA6 is the sequence shown in SEQ ID NO:11 and the antisense strand is the sequence shown in SEQ ID NO:12; the sense strand of siRNA7 is the sequence shown in SEQ ID NO:13 and the antisense strand is the sequence shown in SEQ ID NO:14; and the sense strand of siRNA8 is the sequence shown in SEQ ID NO:14. The sequence shown in NO:15 is the antisense strand, and the sequence shown in SEQ ID NO:16 is the antisense strand; the sequence shown in SEQ ID NO:2 is the sense strand of siRNA9, and the sequence shown in SEQ ID NO:67 is the antisense strand.In some embodiments, PNPLA3 mRNA is one of siRNA1-M1-siRNA9-M1 shown in Table 1B below, wherein the sense strand of siRNA1-M1 is the sequence shown in SEQ ID NO:51, and the antisense strand is the sequence shown in SEQ ID NO:52; the sense strand of siRNA2-M1 is the sequence shown in SEQ ID NO:53, and the antisense strand is the sequence shown in SEQ ID NO:54; the sense strand of siRNA3-M1 is the sequence shown in SEQ ID NO:55, and the antisense strand is the sequence shown in SEQ ID NO:56; the sense strand of siRNA4-M1 is the sequence shown in SEQ ID NO:57, and the antisense strand is the sequence shown in SEQ ID NO:58; the sense strand of siRNA5-M1 is the sequence shown in SEQ ID NO:59, and the antisense strand is the sequence shown in SEQ ID NO:60; the sense strand of siRNA6-M1 is the sequence shown in SEQ ID NO:61, and the antisense strand is the sequence shown in SEQ ID NO:62; and the sense strand of siRNA7-M1 is the sequence shown in SEQ ID NO:54. The sequence shown in SEQ ID NO:63 is the positive strand of siRNA8-M1, and the sequence shown in SEQ ID NO:65 is the negative strand of siRNA8-M1. The sequence shown in SEQ ID NO:66 is the negative strand of siRNA9-M1. The sequence shown in SEQ ID NO:53 is the positive strand of siRNA9-M1, and the sequence shown in SEQ ID NO:68 is the negative strand of siRNA9-M1. Alternatively, the double-stranded oligonucleotide comprises a sense strand and an antisense strand in any one of conjugates 1-13, wherein the sense strand of conjugate 1 is the sequence shown in SEQ ID NO:17 and the antisense strand is the sequence shown in SEQ ID NO:18; the sense strand of conjugate 2 is the sequence shown in SEQ ID NO:19 and the antisense strand is the sequence shown in SEQ ID NO:20; the sense strand of conjugate 3 is the sequence shown in SEQ ID NO:21 and the antisense strand is the sequence shown in SEQ ID NO:22; the sense strand of conjugate 4 is the sequence shown in SEQ ID NO:23 and the antisense strand is the sequence shown in SEQ ID NO:24; the sense strand of conjugate 5 is the sequence shown in SEQ ID NO:25 and the antisense strand is the sequence shown in SEQ ID NO:26; the sense strand of conjugate 6 is the sequence shown in SEQ ID NO:27 and the antisense strand is the sequence shown in SEQ ID NO:28; the sense strand of conjugate 7 is the sequence shown in SEQ ID NO:29 and the antisense strand is the sequence shown in SEQ ID NO:30; and the sense strand of conjugate 8 is the sequence shown in SEQ ID NO:29. The sequence shown in SEQ ID NO:31 is the positive strand of conjugate 9, and the sequence shown in SEQ ID NO:32 is the negative strand of conjugate 10; the sequence shown in SEQ ID NO:33 is the positive strand of conjugate 10, and the sequence shown in SEQ ID NO:36 is the negative strand of conjugate 11; the sequence shown in SEQ ID NO:37 is the positive strand of conjugate 11, and the sequence shown in SEQ ID NO:38 is the negative strand of conjugate 12; the sequence shown in SEQ ID NO:39 is the positive strand of conjugate 12, and the sequence shown in SEQ ID NO:40 is the negative strand of conjugate 13; the sequence shown in SEQ ID NO:41 is the positive strand of conjugate 13, and the sequence shown in SEQ ID NO:42 is the negative strand of conjugate 13. Table 1B: Disclosed siRNA sequences In this context, uppercase letters C, G, U, A, and T represent the base composition of a nucleotide; lowercase letter o indicates that the uppercase letter to the left of o represents an alkoxy-modified nucleotide; lowercase letter f indicates that the uppercase letter to the left of f represents a fluorinated nucleotide; lowercase letter e indicates that the uppercase letter to the left of e represents a substituted alkoxy-modified nucleotide; lowercase letter d indicates that the uppercase letter to the right of d represents a deoxyribonucleotide; and lowercase letter s indicates that the lowercase letter s represents the base composition of a nucleotide. The two closest uppercase letters on either side of the letter indicate that the nucleotides are linked by a phosphate thioester group; the lowercase letter 'x' indicates that the two closest uppercase letters on either side of the letter are linked by a phosphate thioester group or a phosphate thioester group; the letter combination 'P1' indicates that the uppercase letter to the right of the letter combination represents a 5'-hydroxy nucleotide or a 5'-VP modified nucleotide; 'ia' indicates a reverse debased deoxynucleotide; each uppercase letter 'X' independently represents 'T' or 'U'; each uppercase letter 'Y' independently represents 'C' or '5mC' (5-methylcytidine). In some embodiments, each alkoxy-modified nucleotide is a C1-C3 alkoxy-modified nucleotide, such as a ribose 2'-methoxy-modified nucleotide. In some embodiments, each substituted alkoxy-modified nucleotide is independently a C1-C3 alkoxy-modified nucleotide with substituents, each substituent being independently selected from C1-C3 alkoxy groups. In some embodiments, each substituted alkoxy-modified nucleotide is independently a ribose 2'-O-methoxyethyl-modified nucleotide (MOE). In some implementations, the first two lowercase x's at the 5' end of each siRNA positive strand represent phosphate thioester linkages, and the remaining lowercase x's each independently represent phosphate ester linkages. In some implementations, each uppercase X independently represents T; and each uppercase Y independently represents C. In another aspect, this disclosure provides a double-stranded oligonucleotide comprising a sense strand and an antisense strand, each nucleotide in the sense strand and the antisense strand being independently modified or unmodified, the sense strand and the antisense strand being at least partially anticomplementary to form a double-stranded region, wherein the unmodified equivalent sequences of the sense strand and the antisense strand are identical for at least 15 consecutive nucleotides to the nucleotide sequences shown in the sense strand and antisense strand of any one of siRNA1-siRNA9 listed in Table 1A, and wherein there are no more than 3 base differences. In some embodiments, the unmodified equivalent sequences of the sense strand and the antisense strand are identical to the nucleotide sequences shown in the sense strand and antisense strand of any one of siRNA1-siRNA9 listed in Table 1A by at least 15, at least 16, at least 17, at least 18, or 19 consecutive nucleotides, respectively, and there are no more than 3 base differences, no more than 1 base difference, or no base differences. In some embodiments, the unmodified equivalent sequences of the positive and negative strands are of equal length to the nucleotide sequences shown on the positive and negative strands of any one of siRNA1-siRNA9 listed in Table 1A, and respectively have no more than 3 base differences, no more than 1 base difference, or no base differences. In some embodiments, along the 5'-3' direction, the unmodified equivalent sequence of the positive strand is of equal length to the nucleotide sequence shown on the positive strand of any one of siRNA1-siRNA9 listed in Table 1A, and has no more than 1 base difference between positions 1-18, or no base difference; the unmodified equivalent sequence of the negative strand is of equal length to the nucleotide sequence shown on the negative strand of the siRNA, and has no more than 1 base difference between positions 2-21, or no base difference. In some embodiments, the sense strand and antisense strand each independently comprise at least one modified nucleotide. In some embodiments, the sense strand and antisense strand each independently have the modification scheme described above. In some embodiments, the antisense strand has the same modification scheme as the single-stranded oligonucleotide described in this disclosure above. The antisense and / or double-stranded oligonucleotides provided in this disclosure can be obtained using conventional oligonucleotide preparation methods in the art (e.g., solid-phase synthesis and liquid-phase synthesis). Solid-phase synthesis is already available as a commercially available custom service. Modified nucleotide groups can be introduced into the antisense and / or double-stranded oligonucleotides described in this disclosure using appropriately modified nucleoside monomers. Methods for preparing appropriately modified nucleoside monomers and for introducing modified nucleotide groups into antisense and / or double-stranded oligonucleotides are also well known to those skilled in the art. All modified nucleoside monomers are commercially available or prepared using known methods. The double-stranded oligonucleotides provided in this disclosure can be used alone, or in combination with a pharmaceutically acceptable carrier to form a pharmaceutical composition, or in combination with a delivery group to form an oligonucleotide conjugate, or in any other suitable form. Contacting cells with an effective amount of the double-stranded oligonucleotide, the pharmaceutical composition, or the oligonucleotide conjugate to modulate PNPLA3 mRNA, or administering an effective amount of the double-stranded oligonucleotide, the oligonucleotide conjugate, or the pharmaceutical composition to a subject to modulate PNPLA3 mRNA, thereby achieving the therapeutic effect on pathological conditions or diseases associated with PNPLA3 mRNA levels. Oligonucleotide conjugates In another aspect, this disclosure provides an oligonucleotide conjugate comprising an oligonucleotide group and a delivery group conjugated to the oligonucleotide group, wherein the oligonucleotide group is independently formed by removing one or more atoms or groups of atoms from a single-stranded or double-stranded oligonucleotide provided in this disclosure. Those skilled in the art will understand that the RNAi activity of the double-stranded oligonucleotide group formed by this removal is at least the same as or equivalent to the RNAi activity of the double-stranded oligonucleotide itself. In some embodiments, the removal of one or more atoms or groups of atoms does not impair the inhibitory activity or stability of the double-stranded oligonucleotide (e.g., siRNA) against the target mRNA. In some embodiments, the double-stranded oligonucleotide group is formed by removing one atom or group of atoms (e.g., a hydrogen atom, a hydroxyl group, or a phosphate ester group) from a double-stranded oligonucleotide provided in this disclosure. For example, the siRNA group may be a chemical portion formed by removing a hydrogen atom from a phosphate ester bond in siRNA, or a chemical portion formed by removing a hydrogen atom from the 5' hydroxyl group of the 5' terminal nucleotide of the sense or antisense strand in siRNA, or a chemical portion formed by removing a hydrogen atom from the 3' hydroxyl group of the 3' terminal nucleotide of the sense or antisense strand in siRNA. In the context of this disclosure, unless otherwise stated, "conjugation" means the covalent connection between two or more chemical parts, each having a specific function (however, without theoretical limitation, the individual components within the functional chemical part—such as a double-stranded oligonucleotide or a metal ion-ligand chelate—may not necessarily be covalently connected); correspondingly, "conjugation" refers to a compound formed by the covalent connection of the individual chemical parts. Further, "oligonucleotide conjugation" refers to a compound formed by the covalent attachment of one or more functional chemical parts to an oligonucleotide. Oligonucleotide conjugation should be understood, depending on the context, as a collective term for multiple oligonucleotide conjugations or an oligonucleotide conjugation represented by a particular chemical formula. In the context of this disclosure, "conjugated molecule" should be understood as a specific compound that can be reactively conjugated to an oligonucleotide to ultimately form the oligonucleotide conjugation of this disclosure. The delivery group is a group used to deliver a single-stranded or double-stranded oligonucleotide group into cells expressing PNPLA3 mRNA. In some embodiments, the delivery group comprises a linker group and a pharmaceutically acceptable target group, and the single-stranded or double-stranded oligonucleotide group, the linker group, and the target group are covalently or non-covalently linked in sequence, each target group being selected from ligands capable of binding to desialylate glycoprotein receptors on the surface of mammalian hepatocytes. In some embodiments, there are 1-6 target groups. In one embodiment, there are 2-4 target groups. The oligonucleotide group can be non-covalently or covalently conjugated to the delivery group, for example, it can be covalently conjugated to the delivery group. In some embodiments, the oligonucleotide group is a double-stranded oligonucleotide group, and the conjugation site of the double-stranded oligonucleotide group to the delivery group can be at the 3' or 5' end of the sense strand of the double-stranded oligonucleotide, at the 3' or 5' end of the antisense strand, or within the internal sequence of the double-stranded oligonucleotide. In some embodiments, the conjugation site of the double-stranded oligonucleotide group to the delivery group is at the 3' end of the sense strand of the double-stranded oligonucleotide. In some embodiments, the delivery group can be attached to any position on the nucleotide, such as a phosphate group, a 2', 3', or 5'-hydroxyl group of the ribose, or a base. When the delivery group is attached to the 3' or 5' end of a single-stranded or double-stranded oligonucleotide chain, it is typically attached to the oxygen atom formed by removing a hydrogen atom from the 3' or 5'-hydroxyl group of the nucleotide; when the delivery group is attached to the inner sequence of a single-stranded or double-stranded oligonucleotide, it is typically attached to a phosphate group, a ribose ring, or a base. In some embodiments, the delivery group can be attached to the 3'-hydroxyl group of an inner sequence nucleotide of a single-stranded or double-stranded oligonucleotide, in which case the nucleotides are linked by a 2'-5' phosphodiester bond. Various connection methods can be found in the following non-patent literature: Muthiah Manoharan et al. siRNA conjugates carrying sequentially assembled trivalent N-acetylgalactosamine linked through nucleosides elicit robust gene silencing in vivo in hepatocytes. ACS Chemical biology, 2015, 10(5): 1181-7. The entire contents of this article are incorporated herein by reference. In some embodiments, the double-stranded oligonucleotide and the delivery group are linked by acid-labile or reducible chemical bonds that can degrade in the acidic environment of the endosome, thereby converting the double-stranded oligonucleotide group into a free state. For non-degradable conjugations, the delivery group can be attached to the positive and negative strands of either the single-stranded or double-stranded oligonucleotide group to minimize the impact of the conjugation on the activity of the double-stranded oligonucleotide group. The targeting group can be linked to the double-stranded oligonucleotide group via a suitable linker. Those skilled in the art can select a suitable linker based on the specific type of the targeting group. For details on these linkers, the types of targeting groups, and the methods of linking them to the double-stranded oligonucleotide, please refer to the disclosure of WO2015006740A2, the entire disclosure of which is incorporated herein by reference. Each of the target groups is independently a ligand with affinity for desialyl glycoprotein receptors on the surface of mammalian hepatocytes. In some embodiments, each of the target groups is independently a desialyl glycoprotein or a sugar. In some embodiments, each of the target groups is independently selected from D-mannose, L-mannose, D-arabinose, D-xylfuranose, L-xylfuranose, D-glucose, L-glucose, D-galactose, L-galactose, α-D-mannose, β-D-mannose, α-D-mannose, β-D-mannose, α-D-glucose, β-D-glucose, α-D-glucose, β-D-glucose. α-D-Furfural, β-D-Furfural, α-D-Fructose, α-D-Galactopyranose, α-D-Galactopyranose, β-D-Galactopyranose, α-D-Galactopyranose, β-D-Galactopyranose, Glucosamine, Sialic acid, Galactosamine, N-acetylgalactosamine, N-trifluoroacetylgalactosamine, N-propionylgalactosamine, N-butyrylgalactosamine, N-isobutyrylgalactosamine, 2 -Amino-3-O-[(R)-1-carboxyethyl]-2-deoxy-β-D-glucopyranose, 2-deoxy-2-methylamino-L-glucopyranose, 4,6-dideoxy-4-carboxamido-2,3-di-O-methyl-D-mannopyranose, 2-deoxy-2-sulfonamido-D-glucopyranose, N-ethanolyl-α-neuraminic acid, 5-thio-β-D-glucopyranose, 2,3,4 One of the following: tri-O-acetyl-1-thio-6-O-triphenylmethyl-α-D-glucopyranoside methyl ester, 4-thio-β-D-galactopyranose, 3,4,6,7-tetra-O-acetyl-2-deoxy-1,5-dithio-α-D-glucopyranoside ethyl ester, 2,5-dehydrated-D-alosulfonyl, ribose, D-ribose, D-4-thioribose, L-ribose, and L-4-thioribose. In some embodiments, at least one or each of the target groups is galactose or N-acetylgalactosamine. In some embodiments, the linker group in the oligonucleotide conjugate of this disclosure has a structure as shown in formula (301): Where k is an integer from 1 to 5, Indicates the site of covalent linkage of groups; all L A Connect to L C The same atom in; or, each L A Independently connected to L C Different atoms in it. In some implementations, L C It has -NH-C(H) n301 (CH2O-) k The structure shown is such that k is an integer from 1 to 3, and n301 = 3 - k; L B The length is 5-20 atoms. In some implementations, each L A Independently, it is a straight-chain alkylene group with a length of 5-20 carbon atoms, wherein one or more methylene groups are optionally replaced by any one or more groups selected from the group consisting of: C(O), NH, O, S, 1,2,3-triazolyl, butadieneyl. In some implementations, L A Having a structure containing amide bonds as shown in formula (302), L B It has a structure as shown in equation (303): Where, n 302 q 302 and p 302 Each is an independent integer from 2 to 6; optionally, n 302 q 302 and p 302 Each is independently 2 or 3; n 303 n is an integer between 4 and 16, optionally n 303 For integers between 8 and 12, This indicates the site where the group is covalently linked. In some embodiments, the linking group has a structure as shown in formula (304) or formula (305): In the linking group, each L A Each of the target groups is connected via an ether bond and via L C The oxygen atom of the hydroxyl group in some parts is related to L. C Partially linked by ether bonds; L B Through the carbonyl group in formula (303) and LC The nitrogen atom of the amino group in the middle is connected by forming an amide bond, and is connected to the double-stranded oligonucleotide group by forming a phosphate ester bond or a thiophosphate ester bond through the oxygen atom in formula (303). In some embodiments, the oligonucleotide conjugates provided in this disclosure have a structure as shown in formula (305A): Wherein, Nu represents the double-stranded oligonucleotide group formed from the double-stranded oligonucleotides provided in this disclosure. In some embodiments, the linker group in the oligonucleotide conjugate of this disclosure has the structure shown in formula (306): Where, n 306 For each p, the integer is between 0 and 3. 306 Independently, integers from 1 to 6. The site indicates a covalently linked group; the linking group is connected to the target group by an ether bond formed by an oxygen atom marked with *; the linking group is connected to the double-stranded oligonucleotide by at least one of the oxygen atoms marked with # forming a phosphate ester bond or a thiophosphate ester bond, and the remaining oxygen atoms marked with # are connected to hydrogen atoms to form hydroxyl groups, or connected to C1-C3 alkyl groups to form C1-C3 alkoxy groups; In some embodiments, the oligonucleotide conjugates of this disclosure have a structure as shown in formula (307): Wherein, Nu represents the double-stranded oligonucleotide group formed from the double-stranded oligonucleotides provided in this disclosure. In some embodiments, the oligonucleotide conjugates of this disclosure have the structure shown in formula (308): in, n 308 The integers are selected from 2 to 4; Each m 308 Independently selected as an integer from 2 to 5; Each R 308 Independently a hydrogen atom, methyl or ethyl, or two R atoms attached to the same carbon atom. 308 Together with this carbon atom, they form a carbonyl group; One of the groups independently represented by A0 is a double-stranded oligonucleotide group, which is a group formed by removing one atom or group of atoms from the double-stranded oligonucleotide described in this disclosure; the remaining A0 is an independent targeting group, and each targeting group may be the same or different, and its definition and selection range are as described above. Each L1 is independently a divalent linker with a length of 1-70 atoms; This indicates the site where the group is covalently linked. In some embodiments, each L1 is independently a straight-chain alkylene group with a length of 1-70 carbon atoms, wherein one or more carbon atoms are optionally replaced by any one or more groups selected from the group consisting of: C(O), NH, O, S, CH=N, S(O)2, OP(O)2, OP(O)(S), C2-C 10 alkenyl, C2-C 10 Ethyne group, C6-C 10 Aromatic, C3-C 18 Heterocyclic groups and C5-C 10 Heteroaryl; and the linear alkylene group may optionally have substituents of any one or more of the group consisting of: C1-C 10 Alkyl, C6-C 10 Aryl, C5-C 10 heteroaryl, C1-C 10 Halogenated alkyl, -OC1-C 10 Alkyl, OC1-C 10 Alkylphenyl, -C1-C 10 Alkyl-OH, -OC1-C 10 Halogenated alkyl, -SC1-C 10 Alkyl, -SC1-C 10 Alkylphenyl, -C1-C 10 Alkyl-SH, -SC1-C 10 Halogenated alkyl groups, halogenated substituents, -OH, -SH, -NH2, -C1-C 10 Alkyl-NH2,-N(C1-C) 10 Alkyl) (C1-C 10 alkyl), -NH(C1-C 10 Alkyl), N(C1-C) 10 Alkyl) (C1-C 10 alkylphenyl), NH(C1-C 10 Alkylphenyl), cyano, nitro, -CO2H, -C(O)O(C1-C 10 Alkyl), -CON (C1-C) 10 Alkyl) (C1-C 10 Alkyl), -CONH (C1-C) 10 Alkyl groups, -CONH2, -NHC(O) (C1-C) 10 alkyl), -NHC(O)(phenyl), -N(C1-C 10 Alkyl)C(O)(C1-C10 Alkyl), -N(C1-C 10 alkyl)C(O)(phenyl), C(O)C1-C 10 Alkyl, -C(O)C1-C 10 Alkylphenyl, C(O)C1-C 10 Haloalkyl, -OC(O)Cl-C 10 Alkyl group, -SO2 (C1-C) 10 alkyl), -SO2 (phenyl), -SO2 (C1-C 10 Halogenated alkyl groups), -SO2NH2, -SO2NH (C1-C 10 alkyl), -SO2NH (phenyl), -NHSO2 (C1-C 10 Alkyl), -NHSO2 (phenyl) and -NHSO2 (C1-C) 10 (Halogenated alkyl groups). As used herein, “alkyl” refers to a straight-chain or branched alkyl group having a specified number of carbon atoms, typically from 1 to 20 carbon atoms, such as from 1 to 10 carbon atoms, or from 1 to 8 or 1 to 6 carbon atoms. For example, C1-C6 alkyl groups comprise straight-chain and branched alkyl groups with 1 to 6 carbon atoms. When referring to an alkyl residue having a specific number of carbon atoms, it is intended to encompass all branched and straight-chain forms having that number of carbon atoms; thus, for example, “butyl” means including n-butyl, sec-butyl, isobutyl, and tert-butyl; “propyl” includes n-propyl and isopropyl. Alkylenes are subsets of alkyl groups, referring to residues that are identical to alkyl groups but have two connection sites. As used herein, "alkenyl" refers to an unsaturated branched or straight-chain hydrocarbon group having at least one carbon-carbon double bond obtained by removing a hydrogen molecule from an adjacent carbon atom of a parent alkyl group. The group can be in either a cis or trans configuration of the double bond. Typical alkenyl groups include, but are not limited to: vinyl; propenyl, such as propyl-1-en-1-yl, propyl-1-en-2-yl, propyl-2-en-1-yl (allyl), propyl-2-en-2-yl; butenyl, such as buten-1-en-1-yl, buten-1-en-2-yl, 2-methylpropen-1-en-1-yl, buten-2-en-1-yl, buten-2-en-2-yl, buten-1,3-dien-1-yl, buten-1,3-dien-2-yl, etc. In some embodiments, the alkenyl group has 2 to 20 carbon atoms, while in other embodiments, it has 2 to 10, 2 to 8, or 2 to 6 carbon atoms. Subalkenyl groups are a subset of alkenyl groups, referring to residues that are identical to alkenyl groups but have two connection points. As used herein, "alkynyl" refers to an unsaturated branched or straight-chain hydrocarbon group having at least one carbon-carbon triple bond obtained by removing two hydrogen molecules from adjacent carbon atoms of a parent alkyl group. Typical alkynyl groups include, but are not limited to: ethynyl; propynyl, such as prop-1-yn-1-yl, prop-2-yn-1-yl; butynyl, such as but-1-yn-1-yl, but-1-yn-3-yl, but-3-yn-1-yl, etc. In some embodiments, the alkynyl group has 2 to 20 carbon atoms, while in other embodiments, it has 2 to 10, 2 to 8, or 2 to 6 carbon atoms. Ionynyl is a subset of alkynyl, referring to residues that are identical to alkynyl but have two connection sites. As used herein, "alkoxy" refers to an alkyl group with a specified number of carbon atoms connected by oxygen bridges, such as methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, pentooxy, 2-pentoxy, isopentoxy, neopentoxy, hexoxy, 2-hexoxy, 3-hexoxy, 3-methylpentoxy, etc. Alkoxy groups typically have 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms connected by oxygen bridges. As used herein, "aryl" refers to a group derived from an aromatic monocyclic or polycyclic hydrocarbon ring system by removing a hydrogen atom from a ring carbon atom. This aromatic monocyclic or polycyclic hydrocarbon ring system contains only hydrogen and carbon atoms of 6 to 18, wherein at least one ring in the ring system is fully unsaturated, i.e., contains a cyclic, delocalized (4n+2)π-electron system according to Hückel's theory. Aryl groups include, but are not limited to, phenyl, fluorenyl, and naphthyl groups. Alearyl groups are a subset of aryl groups, referring to residues identical to aryl groups but with two connection points. "Heteroaryl" refers to a group derived from a 3- to 18-membered aromatic ring radical, comprising 2 to 17 carbon atoms and 1 to 6 heteroatoms selected from nitrogen, oxygen, and sulfur. As used herein, a heteroaryl can be a monocyclic, bicyclic, tricyclic, or tetracyclic system, wherein at least one ring in the ring system is fully unsaturated, i.e., comprising a cyclic delocalized (4n+2) π-electron system according to Hückel's theory. Heteroaryls include fused ring or bridged ring systems. In some embodiments, the heteroatoms in the heteroaryl are oxidized heteroatoms. In some embodiments, the heteroaryl contains one or more nitrogen atoms. In some embodiments, one or more of the nitrogen atoms in the heteroaryl are quaternized nitrogen atoms. The heteroaryl is attached to the remainder of the molecule via any ring atom. Examples of heteroaryl groups include, but are not limited to: aziridine, heptatrienyl, acridine, benzimidazolyl, benzoindolyl, 1,3-benzodioxazolyl, benzofuranyl, benzooxazolyl, benzo[d]thiazolyl, benzo[b][1,4]dioxepinyl, benzo[b][1,4]oxazinyl, 1,4-benzodioxanyl, benzene benzo[a]furanyl, benzo[a]oxazolyl, benzo[a]dioxolyl, benzo[a]dioxinyl, benzo[a]pyranyl, benzo[a]pyranoneyl, benzo[a]furanyl, benzo[a]furanoneyl, benzo[a]thiophenyl, benzo[a]thiophene[3,2-d]pyrimidinyl, benzo[a]triazolyl, benzo[4,6]imidazo[1,2-a]pyridyl, carbazoleyl, cinnolinyl, cyclopentano[d]pyrimidinyl, 6,7-dihydro-5H-cyclopentano[4,5] Thiophene[2,3-d]pyrimidinyl, 5,6-dihydrobenzo[h]quinazolinyl, 5,6-dihydrobenzo[h]cinnolinyl, 6,7-dihydro-5H-benzo[6,7]cycloheptano[1,2-c]pyridazinyl, dibenzofuranyl, dibenzothiophenyl, furanyl, furanoneyl, furano[3,2-c]pyridinyl, 5,6,7,8 9,10-Hexahydrocyclooctano[d]pyrimidinyl, 5,6,7,8,9,10-Hexahydrocyclooctano[d]pyridazinyl, 5,6,7,8,9,10-Hexahydrocyclooctano[d]pyridinyl, isothiazolyl, imidazolyl, indazolyl, indole, isoyindolyl, dihydroindolyl, isodihydroindolyl, isoquinolinyl, indolizinyl, isoxazolyl, 5,8-methanol-5,6,7,8-tetrahydroquinazolinyl (5,8-methano-5,6,7,8-tetrahydroquinazolinyl), naphthyridinyl, 1,6-naphthyridinonyl, oxadiazolyl, 2-oxoazepinyl, oxazolyl, oxiranyl, 5,6,6a,7,8,9,10,10a-octahydrobenzo[H]quinazolinyl, 1-phenyl-1H-pyrroleyl, phenazinyl, phenothiazinyl, phenotoxazinyl, phthalazinyl, pteridinyl, purine, pyrroleyl, pyrazolyl, pyrazolo[3,4-d]pyrimidinyl, pyridinyl, pyrido[3,2-d]pyrimidinyl, pyrido[3,4-d]pyrimidinyl Pyrimidinyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrroleyl, quinazolinyl, quinoxalinyl, quinolinyl, tetrahydroquinolinyl, 5,6,7,8-tetrahydroquinazolinyl, 5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidinyl, 6,7,8,9-tetrahydro-5H-cycloheptano[4,5]thieno[2,3-d]pyrimidinyl, 5,6,7,8-tetrahydropyridano[4,5-c]pyridazinyl, thiazolyl, thiadiazolyl, triazolyl, tetrazolyl, triazinyl, thieno[2,3-c]pyridinyl, thieno[3,2-d]pyrimidinyl, thieno[2,3-c]pyridinyl, and thiophenyl / thienyl. , In the foregoing or hereinafter, "substituted" groups include substituted alkyl groups, substituted alkoxy groups, substituted amino groups, substituted aliphatic groups, substituted heteroaliphatic groups, substituted acyl groups, substituted aryl groups, or substituted heteroaryl groups. Unless otherwise specified, a "substituted" group refers to a group formed by replacing one or more hydrogen atoms in the group with one or more substituents. For example, "substituted alkoxy" refers to a group formed by replacing one or more hydrogen atoms in the alkoxy group with a substituent. Those skilled in the art will understand that compounds applicable to the present disclosure may contain various substituents, as long as the introduction of such substituents does not affect the function of the present disclosure and achieves the purpose of the present disclosure. In some embodiments, the substituents are selected from the group consisting of C1-C1 groups. 10 Alkyl, C6-C 10 Aryl, C5-C 10 heteroaryl, C1-C 10 Halogenated alkyl, -OC1-C 10 Alkyl, -OC1-C 10 Alkylphenyl, -C1-C 10 Alkyl-OH, -OC1-C 10Halogenated alkyl, -SC1-C 10 Alkyl, -SC1-C 10 Alkylphenyl, -C1-C 10 Alkyl-SH, -SC1-C 10 Halogenated alkyl groups, halogenated substituents, -OH, -SH, -NH2, -C1-C 10 Alkyl-NH2,-N(C1-C) 10 Alkyl) (C1-C 10 alkyl), -NH(C1-C 10 Alkyl), -N(C1-C 10 Alkyl) (C1-C 10 alkylphenyl), -NH(C1-C 10 Alkylphenyl), -CN, -NO2, -CO2H, -C(O)O(C1-C 10 Alkyl), -CON (C1-C) 10 Alkyl) (C1-C 10 Alkyl), -CONH (C1-C) 10 Alkyl group), -CONH2, -NHC(O) (C1-C 10 alkyl), -NHC(O)(phenyl), -N(C1-C 10 Alkyl)C(O)(C1-C 10 Alkyl), -N(C1-C 10 alkyl)C(O)(phenyl), -C(O)C1-C 10 Alkyl, -C(O)C1-C 10 Alkylphenyl, -C(O)C1-C 10 Haloalkyl, -OC(O)Cl-C 10 Alkyl group, -SO2 (C1-C) 10 alkyl), -SO2 (phenyl), -SO2 (C1-C 10 Halogenated alkyl groups), -SO2NH2, -SO2NH (C1-C 10 alkyl), -SO2NH (phenyl), -NHSO2 (C1-C 10 Alkyl), -NHSO2 (phenyl) and -NHSO2 (C1-C) 10 (Halogenated alkyl). In some embodiments, the substituent is one of -C1-C3 alkyl, -C6-C8 aryl, -O-C1-C3 alkyl, -O-(C1-C3 alkyl)phenyl, halogen, -OH, -NH2, -CN or -NO2. Those skilled in the art will understand that for any group containing one or more substituents, these groups are not intended to introduce any substitution or substitution pattern that is spatially impractical, synthetically infeasible, and / or inherently unstable. As used herein, “halogenated” or “halogenated” refers to fluorinated, chlorinated, bromine, and iodinated substances, and the term “halogen” includes fluorine, chlorine, bromine, and iodine. As used herein, “haloalkyl” means an alkyl group as defined above in which a specified number of carbon atoms are replaced by one or more, up to a maximum permissible number of halogen atoms. Examples of haloalkyl groups include, but are not limited to, trifluoromethyl, difluoromethyl, 2-fluoroethyl, and pentafluoroethyl. Those skilled in the art will understand that, although for convenience, L1 is defined as a linking group formed by substitution or substitution of a linear alkylene group, it may not be a linear group or may have a different name, such as an amine or alkenyl group resulting from the aforementioned substitution and / or substitution. Unless otherwise stated, in the chemical structural formulas described in this disclosure, the “length” of any group refers to the number of atoms in the longest atomic chain of that group, excluding hydrogen atoms; in the calculation of group length, when multiple connections are involved between two atoms (e.g., two atoms belong to the same cyclic group, and thus at least two atomic chains contain the two atoms), the length is calculated according to the shortest atomic chain between the two atoms. For example, 1,4-cyclohexanediyl, 1,4-piperidinediyl, 1,4-phenylene, and 1,4-piperazindiyl are all calculated as having a length of 4 atoms, while 1,2-cyclopentadiyl is calculated as having a length of only 2 atoms. The function of L1, covalently linked to A0 representing the double-stranded oligonucleotide group, is to covalently link the double-stranded oligonucleotide group to the target group. This allows the oligonucleotide conjugate containing the double-stranded oligonucleotide group to enter hepatocytes through the targeting effect of the target group, without affecting the regulatory function of the double-stranded oligonucleotide group on PNPLA3 mRNA levels after entering the hepatocytes. Therefore, in some embodiments, the length of L1 covalently linked to A0 representing the double-stranded oligonucleotide group is 3-20 atoms, 4-15 atoms, or 5-12 atoms. In some embodiments, L1 covalently linked to A0 representing the double-stranded oligonucleotide group is selected from one or more of A1, A2, A4, A5, A10, A16, A18, and A19, combined with phosphate ester groups or modified phosphate ester groups. Where j1 is an integer between 2 and 10; This indicates the site where the group is covalently linked. In some embodiments, R2 is selected from at least two of A1, A2, A4, A10 and A16 connected with a phosphate ester group or a modified phosphate ester group; in some embodiments, R2 is selected from at least two of A1, A2, A10 connected with a phosphate ester group or a modified phosphate ester group. In some embodiments, L1, covalently linked to A0 representing a double-stranded oligonucleotide group, has a structure as shown in formulas (B1), (B2), (B3), or (B4): in, L represents the site where groups are covalently linked. B1 and L B2 Whether identical or different, independently selected from one of the following groups or any combination thereof: -(CH2) q1 -、-CH(OH)-、-CH(CH2OH)-、-NH-、-O-、-S-、1,4-cyclohexanediyl、1,4-piperidinidyl、1,4-phenylene、1,4-piperazinidyl、pyrrolidinediyl、where q1 is an integer from 1 to 6, L B1 and L B2 The length of each is independently 1-20 atoms. In some embodiments, L B1 and L B2 The length of each is independently 1-10 atoms. In some embodiments, L B1 and L B2 The length of each atom is 1-6 atoms. L B3 A group selected from phosphate ester groups, thiophosphate ester groups, and dithiophosphate ester groups is covalently linked to the 5' hydroxyl group at the 5' position of the ribose of the sense or antisense strand of the double-stranded oligonucleotide group, or the oxygen atom remaining after removing one hydrogen atom from the 3' hydroxyl group at the 3' position of the ribose of the 3' terminal nucleotide. In some embodiments, L B3 It is a phosphate ester group, covalently linked to the 5' hydroxyl group of the ribose at the 5' end of the positive strand of the double-stranded oligonucleotide group, or the oxygen atom remaining after removing one hydrogen atom from the 3' hydroxyl group of the ribose at the 3' end of the positive strand of the double-stranded oligonucleotide group. In some embodiments, when the oligonucleotide conjugates of this disclosure are prepared by a solid-phase synthesis process, L1, covalently linked to A0 representing a double-stranded oligonucleotide group, needs to simultaneously contain a linking site for N-linking to a nitrogen-containing backbone, a linking site for linking to a double-stranded oligonucleotide group, and a functional group capable of linking to a solid-phase support. In some embodiments, the N-linking site on the nitrogen-containing backbone in L1, covalently linked to A0 representing a double-stranded oligonucleotide group, forms an amide bond with N, is covalently linked to the double-stranded oligonucleotide group via a phosphate ester bond, and the functional group capable of linking to the solid-phase support is a hydroxyl or amino group. In some embodiments, R2 is B5, B6, B5', or B6'. in, This indicates the site where a group is covalently bonded. The value of q2 can be an integer from 1 to 10. In some implementations, q2 is an integer from 1 to 5. The function of L1 covalently linked to A0, representing the target group, is to position the target group in a suitable spatial location, thereby better binding to receptors on the surface of mammalian hepatocytes, and thus specifically targeting and entering the hepatocytes. Therefore, any L1 covalently linked to A0, representing the target group, can be used in this disclosure as long as it has an appropriate length and its chemical properties do not significantly affect delivery. In some embodiments, each L1 covalently linked to the target group is independently a divalent linker with a length of 3-25 atoms. In some embodiments, each L1 covalently linked to A0, representing the target group, has an independent length of 4-15 atoms. In some embodiments, each L1 covalently linked to A0, representing the target group, has a length of 5-10 atoms. In some embodiments, the length of each L1 covalently linked to A0, representing the target group, is the same. In some embodiments, each L1 covalently linked to A0 representing a target group may be the same or different, and is independently selected from the group consisting of groups represented by formulas (L3)-(L18) and any combination thereof: Where each j1 is an integer from 2 to 10; each R' is independently a hydrogen atom or a C1-C3 alkyl group. This indicates the site where the group is covalently linked. For ease of synthesis and / or chemical stability, in some embodiments, each L1 covalently linked to A0 representing a target group is independently a combination of at least two linking units, each linking unit independently having a structure shown in any one of formulas (L3)-(L7). In some embodiments, each linking unit independently has a structure shown in any one of formulas (L3), (L4), and (L7). For ease of synthesis, in some embodiments, each L1 covalently linked to A0 representing a target group includes a carbonyl group bonded to a nitrogen atom shown in formula (308). In some embodiments, each L1 covalently linked to A0 representing a target group independently has the structure shown in formula (L20) or (L21): Where j2 is an integer from 4 to 9, and j3 is 1 or 2. In some embodiments, j2 is 5, 6, or 7, and j3 is 1. In some embodiments, each L1 covalently linked to A0 representing the target group is identical. In the conjugates disclosed herein, the number of targeting groups and the spacing between them are the number and spacing that provide a suitable spatial configuration of multiple targeting groups. For this purpose, n308 and each m308 are independently integers selected from 2 to 4. In some embodiments, n308 is 3 or 4, so that the number of targeting groups in the conjugates of this disclosure is 3 or 4, which enables better binding to hepatocyte surface receptors. In some embodiments, n308 is 3, and each m308 is independently 3 or 4. Those skilled in the art will understand that each R 308 When the individual atoms are hydrogen atoms, methyl groups, or ethyl groups, the delivery effect of the oligonucleotide conjugate is not affected, and the objectives of this disclosure can still be achieved. In some embodiments, for ease of synthesis, each R... 308 Each is an independent hydrogen atom. In some embodiments, the oligonucleotide conjugates of this disclosure have the structures shown in formulas (403), (404), (405), (406), (407), (408), (409), (410), (411), (412), (413), (414), (415), (416), (417), (418), (419), (420), (421), or (422): Wherein, Nu represents an oligonucleotide group, such as a single-stranded oligonucleotide group or a double-stranded oligonucleotide group formed from a single-stranded oligonucleotide or a double-stranded oligonucleotide provided in this disclosure. In some embodiments, the oligonucleotide group is a double-stranded oligonucleotide group, and the P atom shown in the above structural formula is covalently linked to the 3' terminal nucleotide of the positive strand of the double-stranded oligonucleotide group. In some embodiments, the 3' terminal nucleotide of the positive strand of the double-stranded oligonucleotide group is a reverse debased deoxynucleotide, and the P atom shown in the above structural formula is covalently linked to the double-stranded oligonucleotide group by substituting a hydrogen atom in the hydroxyl group of the 3' terminal reverse debased deoxynucleotide of the positive strand of the double-stranded oligonucleotide group represented by Nu, which is connected to the ribose ring via a methylene group. In some embodiments, the P atom shown in formulas (403)-(422) is covalently linked to the oxygen atom remaining after removing one hydrogen atom from the 3' position hydroxyl group of the ribose ring of the 3' terminal nucleotide of the positive strand of the double-stranded oligonucleotide group represented by Nu. In some embodiments, the P atom shown in formulas (403)-(422) is covalently linked to the oxygen atom of the reverse debased deoxynucleotide ia (as shown in formula (35)) at the 3' end of the positive strand of the siRNA represented by Nu, thereby covalently linking it to the positive strand of the siRNA. In some embodiments, the oligonucleotide conjugate of this disclosure has the structure shown in formula (403). In some embodiments, the oligonucleotide conjugate comprises an oligonucleotide group formed from siRNA1-siRNA9; or, the oligonucleotide conjugate comprises a double-stranded oligonucleotide group formed from any one of siRNAs selected from siRNA1-M1, siRNA2-M1, siRNA3-M1, siRNA4-M1, siRNA5-M1, siRNA6-M1, siRNA7-M1, siRNA8-M1, and siRNA9-M1; or, the oligonucleotide conjugate is one of conjugates 1-13. In some embodiments, the double-stranded oligonucleotide group comprised in the oligonucleotide conjugate of this disclosure may be an siRNA group formed by removing an atom or group of atoms from siRNA, in which case the oligonucleotide conjugate of this disclosure is also referred to as an siRNA conjugate. In some embodiments, the double-stranded oligonucleotide group comprised in the oligonucleotide conjugate of this disclosure may be an siRNA group formed from, for example, the siRNAs listed in Table 1A. siRNA conjugates containing these siRNA groups exhibit excellent stability and high PNPLA3 mRNA inhibitory activity. Preparation of oligonucleotide conjugates disclosed herein Those skilled in the art can prepare the oligonucleotide conjugates described herein using various suitable methods. For example, when linking nucleoside monomers one by one according to the sequence and modification scheme of the sense and antisense strands of the double-stranded oligonucleotides described herein using a solid-phase synthesis method, a delivery group can be introduced using methods already described in detail in the prior art to synthesize the oligonucleotide conjugates described herein. For example, WO2015006740A2 describes in detail various methods for preparing oligonucleotide conjugates. When the double-stranded oligonucleotide is siRNA, the oligonucleotide conjugates of this disclosure can also be obtained using methods well known to those skilled in the art. For example, WO2014025805A1 describes a method for preparing the structure shown in formula (305A), and Rajeev et al. describe a method for preparing the structure shown in formula (307) in ChemBioChem 2015, 16, 903-908. Chinese patent application CN110959011A also discloses in detail a method for preparing the oligonucleotide conjugate shown in formula (308). The contents of the above-mentioned documents are incorporated herein by reference in their entirety. Pharmaceutically acceptable salts In another aspect, this disclosure also provides pharmaceutically acceptable salts of the single-stranded oligonucleotides, double-stranded oligonucleotides, or oligonucleotide conjugates described herein. Pharmaceutically acceptable salts are known to those skilled in the art. By forming salts, the pharmaceutically acceptable salts of the single-stranded oligonucleotides, double-stranded oligonucleotides, or oligonucleotide conjugates described herein may exhibit better solubility, bioavailability, or stability than the single-stranded oligonucleotides, double-stranded oligonucleotides, or oligonucleotide conjugates themselves. In some embodiments, in the single-stranded oligonucleotides, double-stranded oligonucleotides, or oligonucleotide conjugates described herein, each adjacent nucleotide is linked by a phosphodiester bond or a thiophosphate diester bond, the non-bridging oxygen or sulfur atom in the phosphodiester bond or thiophosphate diester bond being negatively charged. This phosphodiester bond or thiophosphate diester bond may be present in the form of a hydroxyl or mercapto group, and the hydrogen ion in the hydroxyl or mercapto group may be partially or completely replaced by a cation. The cation may be any cation, such as a metal cation, ammonium ion (NH4+). +The delivery group may contain a salt-forming group, such as a phosphate group. For improved solubility and / or bioavailability, in some embodiments, the pharmaceutically acceptable salt is a partial or complete water-soluble salt of the single-stranded oligonucleotide, the double-stranded oligonucleotide, or the oligonucleotide conjugate. In some embodiments, the water-soluble salt may be an amine salt, an alkali metal salt, or an alkaline earth metal salt. In some embodiments, the amine salt is selected from one or more of ammonium salts, methylamine salts, tertiary amine salts, and quaternary ammonium salts; the alkali metal salt is selected from potassium salts or sodium salts; and the alkaline earth metal salt is selected from calcium salts or magnesium salts. In some embodiments, the tertiary amine salt is one or more of triethylamine salts, triisopropylamine salts, or N,N-diisopropylethylamine salts. In some embodiments, the pharmaceutically acceptable salt of the single-stranded oligonucleotide, double-stranded oligonucleotide, or oligonucleotide conjugate is a sodium salt or a partial sodium salt of the single-stranded oligonucleotide, double-stranded oligonucleotide, or oligonucleotide conjugate. In some embodiments, the pharmaceutically acceptable salt of the single-stranded oligonucleotide, double-stranded oligonucleotide, or oligonucleotide conjugate is a mixture of a methylamine salt and an ammonium salt of the single-stranded oligonucleotide, double-stranded oligonucleotide, or oligonucleotide conjugate. In some embodiments, the pharmaceutically acceptable salt is a salt or a portion of the single-stranded oligonucleotide, double-stranded oligonucleotide, or oligonucleotide conjugate, wherein the salt is one or more of a methylamine salt, a triethylamine salt, or a sodium salt. Pharmaceutical Composition In another aspect, this disclosure also provides a pharmaceutical composition comprising one or more of the single-stranded oligonucleotides, double-stranded oligonucleotides, oligonucleotide conjugates and pharmaceutically acceptable salts thereof provided in this disclosure, and pharmaceutically acceptable excipients. Pharmaceutically acceptable excipients are one or more of the various components commonly used in the art, such as solvents, protectants, osmotic pressure regulators, and one or more other pharmaceutically acceptable carriers. For example, when the pharmaceutical composition is an injection, the pharmaceutically acceptable excipient is a solvent, such as deionized water, water for injection, physiological saline, ethanol, aqueous ethanol solution, or pH buffer. The pH buffer may be a tris(hydroxymethyl)aminomethane hydrochloride buffer with a pH of 7.5-8.5 and / or a phosphate buffer with a pH of 5.5-8.5, for example, a phosphate buffer with a pH of 5.5-8.5. The amount of solvent used is adjusted according to the required solution concentration. Based on the oligonucleotide groups in the double-stranded oligonucleotide, the concentration of the oligonucleotide conjugate in the injection solution can be 0.01 mg / mL-20 mg / mL, 0.1 mg / mL-10 mg / mL, or 0.5 mg / mL-5 mg / mL. The protective agent may be at least one selected from inositol, sorbitol, sucrose, trehalose, mannose, maltose, lactose, and glucose. Based on the total weight of the pharmaceutical composition, the content of the protective agent may be 0.01-30% by weight. The osmotic pressure regulator may be sodium chloride and / or potassium chloride. The content of the osmotic pressure regulator results in an osmotic pressure of 200-700 milliosm / kg (mOsm / kg) for the pharmaceutical composition. The content of the osmotic pressure regulator can be readily determined by those skilled in the art based on the desired osmotic pressure. In some embodiments, the dosage of the formulation made from the pharmaceutical composition may be adjusted during administration depending on the route of administration. In some embodiments, the pharmaceutical composition may be a liquid formulation, such as an injection; or it may be a lyophilized powder for injection, which is mixed with liquid excipients to form a liquid formulation for administration. The liquid formulation may be administered subcutaneously, intramuscularly, or intravenously, or may be delivered via a spray to the lungs, or via a spray to other organs (such as the liver), or orally. In some embodiments, the pharmaceutical composition is administered via subcutaneous injection. Other pharmaceutically acceptable carriers may be carriers conventionally used in the field of double-stranded oligonucleotide drug delivery, such as, but not limited to, magnetic nanoparticles (e.g., Fe3O4 or Fe2O3-based nanoparticles), carbon nanotubes, mesoporous silicon, calcium phosphate nanoparticles, polyethylenimine (PEI), polyamidoamine (PAMAM) dendrimer, poly(L-lysine) (PLL), chitosan, 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), poly(D&L-lactic / glycolic acid) copolymer (PLGA), and poly(2-aminoethyl ethylene) phosphate. One or more of the following: phosphate), PPEEA, and poly(2-dimethylaminoethyl methacrylate), PDMAEMA, and their derivatives. In some embodiments, there are no particular requirements for the content of double-stranded oligonucleotides and pharmaceutically acceptable carriers in the pharmaceutical composition. In some embodiments, the weight ratio of double-stranded oligonucleotides to pharmaceutically acceptable carriers can be 1:(1-500), and in some embodiments, the weight ratio is 1:(1-50). In some embodiments, the pharmaceutical composition may be in the form of a liposomal formulation. In some embodiments, the pharmaceutically acceptable carrier used in the liposomal formulation comprises an amine-containing transfection compound (hereinafter also referred to as an organic amine), a cofactor lipid, and / or a polyethylene glycol-modified lipid. The organic amine, cofactor lipid, and polyethylene glycol-modified lipid may be selected from one or more of the amine-containing transfection compounds or their pharmaceutically acceptable salts or derivatives, cofactor lipids, and polyethylene glycol-modified lipids described in Chinese patent application CN103380113A (which is incorporated herein by reference in its entirety). In some embodiments, the organic amine may be a compound of formula (201) as described in Chinese patent application CN103380113A, or a pharmaceutically acceptable salt thereof: in: X 101 and X 102 Each can be independently O, S, NA, or CA, where A is hydrogen or C1-C. 20 hydrocarbon chain; Y 101 and Z 101 Each can be independently C=O, C=S, S=O, CH-OH, or SO2; R 101 R 102 R 103 R 104 R 105 R 106 and R 107 Each is independently hydrogen, cyclic or acyclic, substituted or unsubstituted, branched or straight aliphatic group, cyclic or acyclic, substituted or unsubstituted, branched or straight heteroaliphatic group, substituted or unsubstituted, branched or straight acyl group, substituted or unsubstituted, branched or straight aryl group, substituted or unsubstituted, branched or straight heteroaryl group; x is an integer from 1 to 10; n is an integer from 1 to 3, m is an integer from 0 to 20, and p is 0 or 1; where, if m = p = 0, then R 102 It is hydrogen; Furthermore, if at least one of n or m is 2, then R 103The nitrogen in formula (201) forms a structure as shown in formula (202) or formula (203): In this context, g, e, and f are each an integer from 1 to 6, "HCC" represents a hydrocarbon chain, and each *N represents a nitrogen atom in formula (201). In some implementations, R 103 It is a polyamine. In other embodiments, R 103 It is a ketal. In some embodiments, R in formula (201) 101 and R 102 Each of them is independently any substituted or unsubstituted, branched or straight-chain alkyl or alkenyl group having 3 to 20 carbon atoms, such as 8 to 18 carbon atoms, and 0 to 4 double bonds, such as 0 to 2 double bonds. In some implementations, if each of n and m independently has a value of 1 or 3, then R 103 It can be any one of the following equations (204)-(213): In equations (204)-(213), g, e, and f are each independent integers from 1 to 6, each "HCC" represents a hydrocarbon chain, and each * indicates R. 103 Possible connection points with nitrogen atoms in equation (201), wherein each H at any * position can be replaced to achieve connection with nitrogen atoms in equation (201). Those skilled in the art can obtain the compound represented by formula (201) by any reasonable method. In some embodiments, the compound represented by formula (201) can be prepared according to the description in Chinese patent application CN103380113A. In some embodiments, the organic amine is an organic amine as shown in formula (214) and / or an organic amine as shown in formula (215): The auxiliary lipid is cholesterol, cholesterol analogues and / or cholesterol derivatives; The PEGylated lipid is 1,2-dipalmitoyl-sn-glycerol-3-phosphatidylethanolamine-N-[methoxy(polyethylene glycol)]-2000. In some embodiments, the molar ratio of the organic amine, the auxiliary lipid, and the polyethylene glycol-modified lipid in the pharmaceutical composition is (19.7-80):(19.7-80):(0.3-50), for example, (50-70):(20-40):(3-20). In some embodiments, the pharmaceutical composition particles formed from the double-stranded oligonucleotide of the present disclosure and the above-mentioned amine-containing transfection reagent have an average diameter of about 30 nm to about 200 nm, typically about 40 nm to about 135 nm, and more typically, the average diameter of the liposome particles is about 50 nm to about 120 nm, about 50 nm to about 100 nm, about 60 nm to about 90 nm, or about 70 nm to about 90 nm. For example, the average diameter of the liposome particles is about 30, 40, 50, 60, 70, 75, 80, 85, 90, 100, 110, 120, 130, 140, 150, or 160 nm. In some embodiments, in the pharmaceutical composition formed from the oligonucleotide or oligonucleotide conjugate of this disclosure and the aforementioned amine-containing transfection reagent, the weight ratio (weight / weight ratio) of the oligonucleotide or oligonucleotide conjugate (based on oligonucleotide groups, the same below) to all lipids (e.g., organic amines, auxiliary lipids, and / or polyethylene glycol-modified lipids) is from about 1:1 to about 1:50, from about 1:1 to about 1:30, from about 1:3 to about 1:20, from about 1:4 to about 1:18. The ratio of the oligonucleotide or oligonucleotide conjugate of this disclosure to the total lipids is in the range of about 1:5 to about 1:17, about 1:5 to about 1:15, about 1:5 to about 1:12, about 1:6 to about 1:12 or about 1:6 to about 1:10, for example, the weight ratio of the oligonucleotide or oligonucleotide conjugate of this disclosure to the total lipids is about 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17 or 1:18. In some embodiments, the components of the pharmaceutical composition may exist independently when sold, and may be in liquid form when used. In some embodiments, the pharmaceutical composition formed by the oligonucleotide or oligonucleotide conjugate provided in this disclosure and the above-described pharmaceutically acceptable carrier can be prepared according to various known methods, simply by replacing existing oligonucleotides with the oligonucleotide or oligonucleotide conjugate provided in this disclosure; in some embodiments, it can be prepared according to the following method: An organic amine, auxiliary lipid, and polyethylene glycol-modified lipid are suspended in an alcohol at the above molar ratio and mixed to obtain a lipid solution. The amount of alcohol used is such that the total mass concentration of the resulting lipid solution is 2-25 mg / mL, for example, 8-18 mg / mL. The alcohol is selected from pharmaceutically acceptable alcohols, such as alcohols that are liquid near room temperature, for example, one or more of ethanol, propylene glycol, benzyl alcohol, glycerol, polyethylene glycol 200, polyethylene glycol 300, and polyethylene glycol 400, for example, ethanol. The oligonucleotide or oligonucleotide conjugate provided in this disclosure is dissolved in a buffer salt solution to obtain an aqueous solution of the oligonucleotide or oligonucleotide conjugate. The concentration of the buffer salt solution is 0.05-0.5M, for example, 0.1-0.2M. The pH of the buffer salt solution is adjusted to 4.0-5.5, for example, 5.0-5.2. The amount of buffer salt solution used is such that the concentration of the oligonucleotide or oligonucleotide conjugate does not exceed 0.6 mg / mL, for example, 0.2-0.4 mg / mL. The buffer salt is selected from one or more of soluble acetate and soluble citrate, for example, sodium acetate and / or potassium acetate. The lipid solution and the aqueous solution of the oligonucleotide or oligonucleotide conjugate are mixed, and the resulting product is incubated at 40-60°C for at least 2 minutes, for example, 5-30 minutes, to obtain the incubated liposome formulation. The volume ratio of the lipid solution to the aqueous solution of the oligonucleotide or oligonucleotide conjugate is 1:(2-5), for example, 1:4. The incubated liposome formulation is concentrated or diluted, impurities are removed, and sterilization is performed to obtain the pharmaceutical composition provided in this disclosure. Its physicochemical parameters are: pH value of 6.5-8, encapsulation efficiency of not less than 80%, particle size of 40-200 nm, polydispersity index of not more than 0.30, and osmotic pressure of 250-400 mOsm / kg; for example, the physicochemical parameters can be: pH value of 7.2-7.6, encapsulation efficiency of not less than 90%, particle size of 60-100 nm, polydispersity index of not more than 0.20, and osmotic pressure of 300-400 mOsm / kg. Concentration or dilution can be performed before, after, or simultaneously with impurity removal. Impurity removal can be achieved using various existing methods, such as ultrafiltration at 100 kDa using a tangential flow system or hollow fiber column, with the ultrafiltration exchange solution being phosphate-buffered saline (PBS) at pH 7.4. Sterilization can be achieved using various existing methods, such as filtration sterilization through a 0.22 μm filter. The use of single-stranded oligonucleotides, double-stranded oligonucleotides, oligonucleotide conjugates, pharmaceutically acceptable salts, and pharmaceutical compositions disclosed herein. This disclosure also provides the use of one or more of the single-stranded oligonucleotides, double-stranded oligonucleotides, oligonucleotide conjugates, pharmaceutically acceptable salts, and pharmaceutical compositions of this disclosure in the preparation of medicaments for treating and / or preventing diseases or symptoms associated with PNPLA3 mRNA levels. In some embodiments, the disease or symptom associated with PNPLA3 mRNA levels is MAFLD. In some embodiments, the disease or symptom associated with PNPLA3 mRNA levels is MASH. This disclosure also provides a method for treating and / or preventing diseases or symptoms associated with PNPLA3 mRNA levels, the method comprising administering to a subject in need an effective amount of one or more of the single-stranded oligonucleotides, double-stranded oligonucleotides, oligonucleotide conjugates, pharmaceutically acceptable salts, and pharmaceutical compositions of this disclosure. In addition, this disclosure also provides a method for regulating the expression level of the PNPLA3 gene in cells, the method comprising contacting the cells with an effective amount of one or more of the single-stranded oligonucleotide, double-stranded oligonucleotide, oligonucleotide conjugate, pharmaceutically acceptable salt and pharmaceutical composition of this disclosure. This disclosure also provides one or more of single-stranded oligonucleotides, double-stranded oligonucleotides, oligonucleotide conjugates, pharmaceutically acceptable salts, and pharmaceutical compositions for use as pharmaceuticals. As used herein, the term "administration" refers to the delivery of one or more of a single-stranded oligonucleotide, double-stranded oligonucleotide, oligonucleotide conjugate, pharmaceutically acceptable salt, and pharmaceutical composition to a subject by means of a method or route that at least partially targets one or more of the single-stranded oligonucleotide, double-stranded oligonucleotide, oligonucleotide conjugate, pharmaceutically acceptable salt, and pharmaceutical composition to a desired site to produce a desired effect. Routes of administration suitable for the methods of this disclosure include local administration and systemic administration. Generally, local administration results in the delivery of more of the single-stranded oligonucleotide, double-stranded oligonucleotide, oligonucleotide conjugate, pharmaceutically acceptable salt, and pharmaceutical composition to a specific site compared to the subject's whole body; while systemic administration results in the delivery of one or more of the single-stranded oligonucleotide, double-stranded oligonucleotide, oligonucleotide conjugate, pharmaceutically acceptable salt, and pharmaceutical composition to substantially the entire body of the subject. The medication may be administered to the subject via any suitable route known in the art, including but not limited to: oral or parenteral routes, such as intravenous administration, intramuscular administration, subcutaneous administration, transdermal administration, airway administration (aerosol), pulmonary administration, nasal administration, rectal administration, and local administration (including oral and sublingual administration). Administration frequency may be once or more daily, weekly, bi-weekly, bi-weekly, monthly, or annually. The dosage of one or more of the single-stranded oligonucleotides, double-stranded oligonucleotides, oligonucleotide conjugates, pharmaceutically acceptable salts, and pharmaceutical compositions described in this disclosure can be conventional in the art, and the dosage can be determined based on various parameters, particularly the age, weight, and sex of the subject. Toxicity and efficacy can be determined in cell culture or laboratory animals using standard pharmaceutical procedures, such as determining the LD50 (the dose that causes 50% of the population to die) and ED50 (the dose that elicits 50% of the maximum response intensity in a quantitative response, and the dose that elicits a positive response in 50% of the subjects in a qualitative response). The range of human dosages can be derived based on data obtained from cell culture analysis and animal studies. When administering the siRNA, pharmaceutical composition, and / or siRNA conjugates described in this disclosure, for example, to male or female C57BL / 6J or C3H / HeNCrlVr mice, 6-12 weeks old, weighing 18-25 g, the amount of siRNA in the siRNA, pharmaceutical composition, and / or siRNA conjugate is as follows: for siRNA conjugates formed by siRNA and pharmaceutically acceptable conjugate molecules, the amount of siRNA may be 0.001-100 mg / kg body weight, in some embodiments 0.01-50 mg / kg body weight, in further embodiments 0.05-20 mg / kg body weight, in even further embodiments 0.1-15 mg / kg body weight, and in still further embodiments 0.1-10 mg / kg body weight. The above amounts are preferred when administering the siRNA, pharmaceutical composition, and / or siRNA conjugates described in this disclosure. The method disclosed herein is used to inhibit PNPLA3 gene expression in cells. The amount of oligonucleotides used in one or more of the following: single-stranded oligonucleotides, double-stranded oligonucleotides, oligonucleotide conjugates, pharmaceutically acceptable salts, and pharmaceutical compositions is readily determined by those skilled in the art based on the desired effect. For example, in some embodiments, the oligonucleotide conjugate is an siRNA conjugate, and the amount of siRNA in the provided siRNA conjugate is sufficient to reduce PNPLA3 mRNA levels and result in an extracellular concentration of 1 pM to 1 μM, or 0.01 nM to 100 nM, or 0.05 nM to 50 nM, or about 5 nM at the surface of target cells. The amount required to achieve this local concentration will vary with various factors, including the delivery method, delivery site, the number of cell layers between the delivery site and the target cells or tissue, and whether the delivery is local or systemic. The concentration at the delivery site can be significantly higher than the concentration at the surface of the target cells or tissue. Reagent test kit This disclosure provides a kit comprising one or more of the single-stranded oligonucleotides, double-stranded oligonucleotides, oligonucleotide conjugates, and pharmaceutically acceptable salts and pharmaceutical compositions provided in this disclosure. In some embodiments, the kits described herein may provide one or more of the single-stranded oligonucleotides, double-stranded oligonucleotides, oligonucleotide conjugates, and pharmaceutically acceptable salts and pharmaceutical compositions of the present disclosure in a single container. In some embodiments, the kits described herein may include a container providing a pharmaceutically acceptable excipient. In some embodiments, the kits may also contain other components, such as stabilizers or preservatives. In some embodiments, the kits described herein may contain at least one other therapeutic agent in a container other than the container providing one or more of the single-stranded oligonucleotides, double-stranded oligonucleotides, oligonucleotide conjugates, pharmaceutically acceptable salts and pharmaceutical compositions described herein. In some embodiments, the kit may include instructions for mixing one or more of the single-stranded oligonucleotides, double-stranded oligonucleotides, oligonucleotide conjugates, pharmaceutically acceptable salts, and pharmaceutical compositions of this disclosure with a pharmaceutically acceptable carrier and / or excipients or other ingredients (if any). In the kits disclosed herein, one or more of the single-stranded oligonucleotides, double-stranded oligonucleotides, oligonucleotide conjugates, pharmaceutically acceptable salts, and pharmaceutical compositions, and / or pharmaceutically acceptable excipients, may be provided in any form, such as liquid, dry, or lyophilized. In some embodiments, one or more of the single-stranded oligonucleotides, double-stranded oligonucleotides, oligonucleotide conjugates, pharmaceutically acceptable salts, and pharmaceutical compositions, and optionally pharmaceutically acceptable excipients, are substantially pure and / or sterile. In some embodiments, sterile water may be provided in the kits disclosed herein. The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited thereto. Without intending to be limiting, the invention is further described in detail below in the embodiments and in exemplary embodiments relating to small interfering RNA (siRNA) in pharmaceutical compositions and / or oligonucleotide conjugates of this disclosure. In this context, the double-stranded oligonucleotides, pharmaceutical compositions, and oligonucleotide conjugates of this disclosure are siRNA, siRNA-containing pharmaceutical compositions, and siRNA conjugates, respectively. In the context of this disclosure, for ease of description, the siRNA, siRNA-containing pharmaceutical compositions, and siRNA conjugates in these embodiments are also referred to as the siRNA, pharmaceutical compositions, and siRNA conjugates of this disclosure. This does not mean that the double-stranded oligonucleotides of this disclosure can only be siRNA; rather, the double-stranded oligonucleotides can be other variants disclosed herein or known to those skilled in the art, such as small activating RNA (saRNA), etc. It is contemplated that, based on the detailed description of siRNA, siRNA-containing pharmaceutical compositions, and siRNA conjugates, other double-stranded oligonucleotides will similarly function when used alone or in the formation of the pharmaceutical compositions and / or oligonucleotide conjugates described in this disclosure. Example Unless otherwise specified, the reagents and culture media used in the following examples are all commercially available products, and the nucleic acid electrophoresis, real-time PCR and other operations used are all performed in accordance with the methods described in Molecular Cloning (Cold Spring Harbor LBboratory Press (1989)). Preparation Examples 1-13 Synthesis of siRNA conjugates 1-13 provided in this disclosure Following the preparation method described in Preparation Example 13 of CN110959011A, conjugates 1-13 as shown in Table 2 were prepared, with the only difference being that the sense and antisense strands of the siRNA contained in the conjugates are as shown in Table 2. For nucleic acid sequences containing the sense and antisense strand sequences of conjugates 1-13 siRNA according to the sequences in Table 2 below, nucleoside phosphoramide monomers were linked one by one to synthesize the sense and antisense strands of siRNA. After preparation, conjugates 1-8 were purified by centrifugal ultrafiltration using a 3K (MWCO) ultrafiltration tube; each of conjugates 1-8 is a mixture of methylamine salt and ammonium salt of a compound having the structure shown in formula (403). Conjugates 9-13 were first purified by self-packed column ionization using strong anion exchange packing material, and then purified by desalting using a HiPrep 26 / 10 desalting pre-packed column; conjugates 9-13 are sodium salts of a compound having the structure shown in formula (403). Conjugates 1-13 are each compounds having the structure shown in formula (403), where the P atom shown in formula (403) is covalently linked to the oxygen atom at the 3' end of the positive strand of the siRNA represented by Nu, as shown in formula (35), and the oxygen atom is linked to the ribose ring via a methylene group, thereby covalently linking to the positive strand of the siRNA. Furthermore, the siRNA contained in these siRNA conjugates has the siRNA sequences corresponding to conjugates 1-13 in Table 2. Each siRNA conjugate was diluted to a concentration of 0.2 mg / mL (based on siRNA) using ultrapure water (Milli-Q ultrapure water system, resistivity 18.2 MΩ*cm (25℃)), and then the molecular weight was determined using liquid chromatography-mass spectrometry (LC-MS, Liquid Chromatography-Mass Spectrometry, purchased from Waters, model: LCT Premier). Among them, the theoretical molecular weight of the positive chain of conjugate 1 is 7336.35, and the measured molecular weight is 7336.42; the theoretical molecular weight of the antisense chain is 7066.77, and the measured molecular weight is 7066.82. The theoretical molecular weight of the positive chain of conjugate 2 is 7503.49, and the measured molecular weight is 7502.23; the theoretical molecular weight of the antisense chain is 6873.63, and the measured molecular weight is 6873.5. The theoretical molecular weight of the positive chain of conjugate 3 is 7433.38, and the measured molecular weight is 7433.20; the theoretical molecular weight of the antisense chain is 6930.69, and the measured molecular weight is 6930.96. The theoretical molecular weight of the positive chain of conjugate 4 is 73... 11.34, the measured molecular weight is 7311.29, the theoretical molecular weight of the antisense chain is 7104.83, and the measured molecular weight is 7104.84; the theoretical molecular weight of the positive chain of conjugate 5 is 7355.29, and the measured molecular weight is 7355.37, the theoretical molecular weight of the antisense chain is 7032.80, and the measured molecular weight is 7032.85; the theoretical molecular weight of the positive chain of conjugate 6 is 7313.30, and the measured molecular weight is 7313.16, the theoretical molecular weight of the antisense chain is 7096.85, and the measured molecular weight is 7096.93; the theoretical molecular weight of the positive chain of conjugate 7 is 7345.30, and the measured molecular weight is 7344.55. The theoretical molecular weight of the antisense chain is 7125.89, and the measured molecular weight is 7125.35; the theoretical molecular weight of the positive chain of conjugate 8 is 7396.30, and the measured molecular weight is 7396.47, while the theoretical molecular weight of the antisense chain is 6999.82, and the measured molecular weight is 6999.89; the theoretical molecular weight of the positive chain of conjugate 9 is 7535.61, and the measured molecular weight is 7535.36, while the theoretical molecular weight of the antisense chain is 6873.63, and the measured molecular weight is 6873.36; the theoretical molecular weight of the positive chain of conjugate 10 is 7387.42, and the measured molecular weight is 7387.11, while the theoretical molecular weight of the antisense chain is 7032.8. 0, with a measured molecular weight of 7032.48; the theoretical molecular weight of the positive chain of conjugate 11 is 7535.61, and the measured molecular weight is 7535.14, while the theoretical molecular weight of the antisense chain is 6950.60, and the measured molecular weight is 6950.09; the theoretical molecular weight of the positive chain of conjugate 12 is 7387.41, and the measured molecular weight is 7387.06, while the theoretical molecular weight of the antisense chain is 7108.79, and the measured molecular weight is 7108.34; the theoretical molecular weight of the positive chain of conjugate 13 is 7535.60, and the measured molecular weight is 7535.95, while the theoretical molecular weight of the antisense chain is 6949.62, and the measured molecular weight is 6949.89. The measured values ​​are consistent with the theoretical values, indicating that the synthesized conjugates 1-13 have the target double-stranded nucleic acid sequence. Table 2. siRNA sequences in siRNA conjugates In this context, uppercase letters C, G, U, A, and T represent the base composition of the nucleotide; lowercase letter m indicates that the nucleotide represented by the uppercase letter to the left of m is 2'-methoxy modified; lowercase letter f indicates that the nucleotide represented by the uppercase letter to the left of f is 2'-fluoro modified; (moe) indicates that the nucleotide represented by the uppercase letter to the left of (moe) is ribose 2'-O-methoxyethyl modified; lowercase letter s indicates that the linking group between the two uppercase letters to the left and right of s is a thiophosphate group; lowercase letter d indicates that the nucleotide represented by the uppercase letter to the right of d is a deoxyribonucleotide; VP indicates that the nucleotide represented by the uppercase letter to the right of s is 5'-vinyl phosphate (VP) modified; and ia indicates a reverse debased deoxynucleotide. Experimental Example 1: Inhibitory activity of the disclosed conjugate in vitro This experiment investigated the inhibitory activity of conjugates 1, 2, 5, 7, and 8 against the hPNPLA3 gene in HepG2 human hepatocellular carcinoma cells in vitro at concentrations of 50 nM, 5 nM, and 0.5 nM. The specific steps are as follows: [1] Cell culture HepG2 human liver cancer cells (purchased from Nanjing Kebai Biotechnology Co., Ltd.) were cultured in DMEM medium (HyClone) supplemented with 10% fetal bovine serum (FBS, GIBCO), 1% NEAA, and 1 mM NAP at 37°C in an incubator containing 5% CO2 / 95% air. HepG2 cells were used at a rate of 5 x 10 4 Cells were seeded into 24-well plates with 0.5 mL of cell culture per well. After culturing for 16 h, the culture medium in the wells was aspirated, and 0.5 mL of Opti-MEM medium (GIBCO) was added to each well. The cells were then cultured for another 1.5 h. [2] Transfection For each siRNA conjugate to be tested, working solutions of 20 μM, 2 μM, and 0.2 μM were prepared using PBS. The siRNA conjugates used were conjugates 1, 2, 5, 7, and 8. For each siRNA conjugate to be tested, prepare a 1A1 solution. Each 1A1 solution contains 1.5 μL of 20 μM working solution of the conjugate and 48.5 μL of cell maintenance culture medium. For each siRNA conjugate to be tested, prepare a 1A2 solution. Each 1A2 solution contains 1.5 μL of 2 μM working solution of the conjugate and 48.5 μL of cell maintenance culture medium. For each siRNA conjugate to be tested, prepare a 1A3 solution. Each 1A3 solution contains 1.5 μL of 0.2 μM working solution of the conjugate and 48.5 μL of cell maintenance culture medium. For each siRNA conjugate to be tested, prepare a 1B solution, each 1B solution containing 1.5 μL of Lipofectamine. TM RNAiMAX (Invitrogen) and 48.5 μL Opti-MEM medium. For each siRNA conjugate, one portion of solution 1A1 and one portion of solution 1B were mixed and incubated at room temperature for 20 min to obtain transfection complex X1. Transfection complex X1 of each siRNA conjugate was added to two culture wells (both containing HepG2 human liver cancer cells and 0.5 mL Opti-MEM medium, hereinafter the same), and mixed thoroughly. The addition volume was 100 μL / well, resulting in a transfection mixture with a concentration of 50 nM (based on the amount of siRNA, hereinafter the same). Transfection complex X1 of each siRNA conjugate was used to transfect two culture wells to obtain a transfection mixture containing the siRNA conjugate, denoted as test group X. a1 -X a5 . For each siRNA conjugate, one portion of solution 1A2 and one portion of solution 1B were mixed and incubated at room temperature for 20 min to obtain transfection complex X2. Transfection complex X2 of each siRNA conjugate was added to two culture wells (both containing HepG2 human liver cancer cells and 0.5 mL Opti-MEM medium, hereinafter the same), and mixed thoroughly. The addition volume was 100 μL / well, resulting in a transfection mixture with a concentration of 5 nM (based on the amount of siRNA, hereinafter the same). Transfection complex X1 of each siRNA conjugate was then transfected into two culture wells to obtain a transfection mixture containing the siRNA conjugate, denoted as test group X. b1 -X b5 . For each siRNA conjugate, one portion of solution 1A3 and one portion of solution 1B were mixed and incubated at room temperature for 20 min to obtain transfection complex X3. Transfection complex X3 of each siRNA conjugate was added to two culture wells (both containing HepG2 human liver cancer cells and 0.5 mL Opti-MEM medium, hereinafter the same), and mixed thoroughly. The addition volume was 100 μL / well, resulting in a transfection mixture with a concentration of 0.5 nM (based on the amount of siRNA, hereinafter the same). Transfection complex X1 of each siRNA conjugate was transfected into two culture wells to obtain a transfection mixture containing the siRNA conjugate, denoted as test group X. c1 -X c5 . The blank control group was treated with 100 μL of Opti-MEM per well, for a total of two culture wells. Test group X above a1 -X a5 X b1 -X b5 X c1 -X c5 Both the control and blank control groups were placed in an incubator with an air atmosphere containing 5% CO2 and cultured at 37°C for 24 hours. [3] Detection Total RNA was extracted from cells in each well using Trizol (Sigma-Aldrich) according to the method described in the instruction manual. For each well of cells, 1 μg of total RNA was extracted and reverse transcribed into cDNA using the Reverse Transcription System kit (Promega) according to its instructions, yielding a solution containing cDNA. The reverse transcription conditions were as follows: for each reverse transcription reaction system, the system was incubated at 70°C for 10 min, then at 42°C for 30 min, at 95°C for 5 min, and finally at 4°C for 5 min or more. After the reaction, 80 μL of DEPC water was added to the reverse transcription system to obtain a solution containing cDNA. For each reverse transcription reaction system, 5 μL of the above-mentioned cDNA-containing solution was used as a template. A 20 μL qPCR reaction system was prepared using reagents provided by SYBR Select Master Mix (Thermo Fisher Scientific). The PCR primer sequences for amplifying the target gene hPNPLA3 and the internal reference gene GAPDH are shown in Table 3, with a final concentration of 10 μM for each primer. Each qPCR reaction system was placed on an ABI StepOnePlus Real-Time PCR instrument and amplified using a three-step method. The amplification program was: 95℃ pre-denaturation for 10 min, followed by 95℃ denaturation for 30 s, 60℃ annealing for 30 s, and 72℃ extension for 30 s. This denaturation, annealing, and extension process was repeated 40 times to obtain product W1 containing amplified target gene hPNPLA3 and internal reference gene GAPDH. Product W1 was then subjected to a gradient temperature increase to 95℃ for 15s, 60℃ for 1min, and then to 95℃ with fluorescence signals collected every 0.3℃. After 15s at 95℃, the melting curves of the target gene and the internal reference gene GAPDH in product W1 were collected by a real-time quantitative PCR instrument to obtain the Ct values ​​of the target gene hPNPLA3 and the internal reference gene GAPDH. Table 3 Primer Information The relative quantitative calculation of the expression level of the target gene hPNPLA3 mRNA in each test group was performed using the Ct(ΔΔCt) method. The calculation method is as follows: ΔCt(test group) = Ct(target gene in test group) - Ct(internal reference gene in test group) ΔCt(control group) = Ct(target gene in control group) - Ct(internal reference gene in control group) ΔCt(test group) = ΔCt(test group) - ΔCt(control group average) ΔCt(control group) = ΔCt(control group) - ΔCt(control group average) Here, ΔCt (control group average) is the arithmetic mean of ΔCt (control group) from each of the two culture wells in the blank control group. Therefore, each culture well in the test group and the control group corresponds to a ΔCt value. Using the mean value of the blank control group as a baseline, the expression level of hPNPLA3 mRNA in the test group was normalized, and the mean value of hPNPLA3 mRNA expression level in the blank control group was defined as 100%. The relative expression level of hPNPLA3 mRNA in the test group = 2 - ΔΔCt(test group) × 100% The inhibition rate of hPNPLA3 mRNA in the test group = (1 - relative expression level of hPNPLA3 mRNA in the test group) × 100%. The inhibition rates of each conjugate on hPNPLA3 mRNA are summarized in Table 4 below: Table 4. Inhibition rate of each conjugate on the target gene hPNPLA3 mRNA Table 4 shows that, in HepG2 cells in vitro, the various siRNA conjugates provided in this disclosure all exhibited good inhibitory effects against the target gene hPNPLA3 mRNA. At a concentration of 50 nM, conjugate 2 showed the highest inhibition rate against hPNPLA3 mRNA, reaching 82.2%, demonstrating significant in vitro activity. Even when the concentration was reduced to 5 nM and 0.5 nM, the conjugates maintained a certain level of inhibition, especially conjugate 2, which showed inhibition rates of 67.3% and 68.3% at 5 nM and 0.5 nM, respectively, while conjugate 5 also achieved an inhibition rate of 73.0% at 5 nM. Experimental Example 2: Inhibition of hPNPLA3 mRNA expression by conjugates 1-8 in mice This experiment investigated the inhibitory activity of conjugates 1-8 on the hPNPLA3 gene in humanized PNPLA3 148M transgenic mice. Humanized PNPLA3 148M transgenic mice (all female, purchased from Jicui Pharmaceutical Co., Ltd.) were randomly divided into groups of 5 mice each, and each group was numbered. Each group of mice was administered the test conjugates 1-8 subcutaneously at a dose of 9 mg / kg (based on siRNA). The siRNA conjugates were provided as a 0.9% sodium chloride aqueous solution containing 1.8 mg / mL of the siRNA conjugate, with an administration volume of 5 mL / kg. One group of mice was given 1×PBS at a volume of 5 mL / kg as the control group. The animals were sacrificed on day 8 after administration, with the time of administration taken as day 1. Liver tissue was collected from each mouse and preserved using RNA later (Sigma-Aldrich). The liver tissue was homogenized using a tissue homogenizer and then total RNA was extracted using Trizol (Sigma-Aldrich) according to the procedure described in the manufacturer's instructions. For each mouse liver tissue, 1 μg of total RNA was extracted and reverse transcribed into cDNA using the Reverse Transcription System kit (Promega) according to its instructions, yielding a solution containing cDNA. The reverse transcription conditions were as follows: for each reverse transcription reaction system, the system was incubated at 70°C for 10 min, then at 42°C for 30 min, at 95°C for 5 min, and finally at 4°C for 5 min or more. After the reaction, 80 μL of DEPC water was added to the reverse transcription system to obtain a solution containing cDNA. For each reverse transcription reaction system, 5 μL of the above-mentioned cDNA-containing solution was used as a template. A 20 μL qPCR reaction system was prepared using reagents provided by the real-time PCR kit (Beijing Kangwei Century Biotechnology Co., Ltd.). The PCR primer sequences for amplifying the target gene PNPLA3 and the internal reference gene GAPDH are shown in Table 3, with a final concentration of 0.25 μM for each primer. Each qPCR reaction system was placed on an ABI StepOnePlus Real-Time PCR instrument, and a three-step amplification method was used. The amplification program was: 95℃ pre-denaturation for 10 min, followed by 95℃ denaturation for 30 s, 60℃ annealing for 30 s, and 72℃ extension for 30 s. This denaturation, annealing, and extension process was repeated 40 times to obtain product W1 containing amplified target gene PNPLA3 and internal reference gene GAPDH. Product W1 was then incubated sequentially at 95℃ for 15s, 60℃ for 1min, and 95℃ for 15s. The melting curves of the target gene PNPLA3 and the internal reference gene GAPDH in product W1 were collected by real-time quantitative PCR instrument to obtain the Ct values ​​of the target gene PNPLA3 and the internal reference gene GAPDH. In the calculation of PNPLA3 mRNA expression level and inhibition rate, the control group consisted of mice administered PBS in this experiment, and the test group consisted of mice administered different conjugates 1-8. The PNPLA3 mRNA expression level in the control group was recorded as 100%, and the corresponding inhibition rate of PNPLA3 mRNA expression level was recorded as 0%. The test results were standardized based on the PNPLA3 mRNA expression level in the control group. The primer information and calculation process are shown in Experiment Example 1, and the results are shown in Table 5 below. Table 5: PNPLA3 mRNA inhibition rate of different conjugates As shown in Table 5, the conjugates provided in this disclosure all exhibited significant inhibitory effects on PNPLA3 mRNA at a concentration of 9 mg / kg siRNA. Specifically, the inhibition rates of these conjugates ranged from 81.3% to 97.1%, with most conjugates showing inhibition rates close to or exceeding 90%. Example 3: In vitro inhibitory activity of conjugates 9-12. This example investigated the inhibitory activity of conjugates 9, 10, 11, and 12 on the hPNPLA3 gene in HepG2 human liver cancer cells at concentrations of 50 nM and 5 nM. The specific steps are as follows: HepG2 cells were cultured using the same method as in Experimental Example 1, at a density of 5 x 10⁻⁶ cells / year. 4 Cells were seeded into 24-well plates with 0.5 mL of cell culture per well. After culturing for about 16 h, the culture medium in the wells was aspirated, and 0.5 mL of Opti-MEM medium (GIBCO) was added to each well. The cells were then cultured for another 1.5 h. For each siRNA conjugate to be tested, working solutions of 20 μM and 2 μM were prepared using PBS. The siRNA conjugates used were conjugates 9, 10, 11, and 12. For each siRNA conjugate to be tested, a 3A1 solution was prepared, each containing 1.5 μL of 20 μM working solution of the conjugate and 48.5 μL of cell maintenance culture medium. For each siRNA conjugate to be tested, a 3A2 solution was prepared, each containing 1.5 μL of 2 μM working solution of the conjugate and 48.5 μL of cell maintenance culture medium. For each siRNA conjugate to be tested, prepare a 3B solution, each containing 1.5 μL of Lipofectamine. TM RNAiMAX (Invitrogen) and 48.5 μL Opti-MEM medium. For each siRNA conjugate, one portion of solution 3A1 and one portion of solution 3B were mixed and incubated at room temperature for 20 min to obtain transfection complex 3X1. In each culture well (all containing HepG2 human liver cancer cells and 0.5 mL Opti-MEM medium, hereinafter the same), 100 μL of transfection complex 3X1 for each siRNA conjugate was added and mixed thoroughly to obtain a transfection mixture with a concentration of 50 nM (based on the amount of siRNA). Each siRNA conjugate transfection complex 3X1 was transfected into two culture wells to obtain a transfection mixture containing the siRNA conjugate, denoted as test group 3X. a1 -3X a4 . For each siRNA conjugate, one portion of solution 3A2 and one portion of solution 3B were mixed and incubated at room temperature for 20 min to obtain transfection complex 3X2. Transfection complex X2 of each siRNA conjugate was added to two culture wells (both containing HepG2 human liver cancer cells and 1 mL of Opti-MEM medium, hereinafter the same), and mixed thoroughly. The addition volume was 100 μL / well, resulting in a transfection mixture with a concentration of 5 nM (based on the amount of siRNA, hereinafter the same). Transfection complex X1 of each siRNA conjugate was transfected into two culture wells to obtain a transfection mixture containing the siRNA conjugate, denoted as test group 3X. b1 -3X b4 . The blank control group was treated with 100 μL of Opti-MEM per well, for a total of two culture wells. The above test group 3X a1 -3X a4 3X b1 -3X b4 Both the control and blank control groups were placed in an incubator with an air atmosphere containing 5% CO2 and cultured at 37°C for 24 hours. Total RNA and reverse transcription were extracted from cells in each well using the same method as in Experiment 1, and the relative quantification of the target gene PNPLA3 mRNA in each test group was calculated. The results are shown in Table 6 below. Table 6 shows the inhibition rates of each conjugate on the target gene hPNPLA3 mRNA. The results in Table 6 show that the various siRNA conjugates provided in this disclosure exhibit good inhibitory effects in HepG2 cells in vitro. Inhibitory activity of conjugate 11-13 in primary monkey liver cells (Example 4) This experiment investigated the inhibitory activity of conjugates 11, 12, and 13 on the hPNPLA3 gene in primary monkey liver cells at concentrations of 10 nM, 1 nM, and 0.1 nM. The specific steps are as follows: [1] Cell plating Primary monkey liver cells were revived (purchased from Miaoshun (Shanghai) Biotechnology Co., Ltd.). The primary monkey liver cells were cultured at 1x10⁶ cells / cells using the pre-contained plating medium. 5 Cells were seeded into 12-well plates with 1 mL of cell culture per well. After culturing for 16 h, the culture medium in the wells was aspirated, and 1 mL of maintenance medium was added to each well. The cells were then cultured for another 1.5 h. [2] Transfection For each siRNA conjugate to be tested, a working solution of the conjugate was prepared with PBS at a concentration of 20 μM (based on the amount of siRNA in the conjugate). The siRNA conjugates used were 11, 12, and 13. Prepare 4A solutions, each containing 3 μL of the conjugate working solution and 97 μL of Opti-MEM medium. Prepare 4B solutions, each containing 3 μL of Lipofectamine. TM RNAMAX (Invitrogen) and 97 μL Opti-MEM medium. For each conjugate, one portion of solution 4A and one portion of solution 4B were mixed to obtain transfection complex 4X1. In each culture well (all containing primary monkey liver cells and 1 mL of Opti-MEM medium, hereinafter the same), 200 μL of transfection complex 4X1 for each siRNA conjugate was added and mixed thoroughly to obtain a transfection complex concentration of 50 nM (based on the amount of siRNA). Each siRNA conjugate transfection complex 4X1 was transfected into two culture wells to obtain a transfection mixture containing the siRNA conjugate, denoted as test group 4X. a1 -4X a4 This is designated as the test group. The blank control group was treated with 200 μL of Opti-MEM per well, for a total of two culture wells. Total RNA was extracted from cells in each well using the same method as in Experiment 1, and reverse transcription was performed to calculate the relative quantification of the target gene PNPLA3 mRNA in each test group. The difference is that the primer sequences used in this experiment are shown in Table 7 below: Table 7 Primer Information The inhibition rates of each conjugate on PNPLA3 mRNA are shown in Table 8 below: Table 8. Inhibition rate of each conjugate on the target gene PNPLA3 mRNA The results in Table 8 show that the siRNA conjugates provided in this disclosure have a significant inhibitory effect on the target gene PNPLA3 mRNA in primary monkey liver cells. All tested conjugates showed an inhibition rate of over 73% against PNPLA3 mRNA at a concentration of 10 nM, with conjugates 11 and 13 even achieving an inhibition rate of 86.4%. Even at a low concentration of 0.1 nM, the inhibition rate against PNPLA3 mRNA still reached 67%. Inhibitory activity of conjugate 9-12 in AAV-hPNPLA3 148M mice in Experiment Example 5 This experiment investigated the inhibitory efficiency of conjugates 9, 10, 11, and 12 on hPNPLA3 148M mRNA expression in an AAV-hPNPLA3 148M mouse model. hPNPLA3 148M AAV8 adeno-associated virus was prepared by Shandong Weizhen Biotechnology Co., Ltd. The adeno-associated virus vector pAV-TBG was selected, and the transfected fragment was a 1446 bp sequence (mRNA NCBI reference: NM_025225.3) from the CDS region (108-1553) of the human PNPLA3 148M gene, with the C at position 444 changed to G, resulting in hPNPLA3 148M AAV8. C57BL / 6J mice (all male) were randomly divided into groups of six, and each group was numbered. Each group of mice was administered the test conjugate 9-12 subcutaneously at a dose of 9 mg / kg (based on siRNA). The siRNA conjugate was provided as a 0.9% sodium chloride aqueous solution containing 1.8 mg / mL of the siRNA conjugate, with an administration volume of 5 mL / kg. One group of mice was given 1×PBS at a volume of 5 mL / kg as the control group. Three days after administration, each mouse was given 1 × 10⁻⁶ hPNPLA3 148MAAV8 adeno-associated virus via tail vein administration. 11 vg. hPNPLA3 148M AAV8 at 5×10 11 The titer is provided in vg / ml, and the administration volume is 200μL / animal. Using the AAV injection time point as day 1, animals were sacrificed on day 8, and liver tissue from each mouse was collected and preserved using RNA later (Sigma Aldrich). The liver tissue was homogenized using a tissue homogenizer, and total RNA was extracted using Trizol (Sigma Aldrich) according to the manufacturer's instructions. Following the procedure in Example 2, the inhibitory activity of PNPLA3148M mRNA was measured and calculated. The results are shown in Table 9 below. Table 9 shows the inhibition rates of each conjugate on the target gene PNPLA3 148M mRNA. As shown in Table 9, in the AAV-hPNPLA3 148M mouse model, the conjugates provided in this disclosure all showed good inhibition rates at a siRNA dosage of 9 mg / kg. Conjugates 9, 11, and 12 showed inhibition rates of over 80% against PNPLA3 148M mRNA. Inhibitory activity of conjugates 11 and 13 in AAV-hPNPLA3 148M mice in Experiment Example 6 This experiment investigated the inhibitory efficiency of conjugates 11 and 13 prepared in the preparation example on the expression of hPNPLA3 148M mRNA in AAV-induced humanized mice. C57BL / 6J mice were randomly divided into two groups (all males): a PBS group of 20 mice and other groups of 15 mice each, and were numbered accordingly. hPNPLA3 148M AAV8 adeno-associated virus was prepared by Shandong Weizhen Biotechnology Co., Ltd., and the plasmid construction method is as described in Example 5. Each mouse was administered 1 × 10⁻⁶ hPNPLA3 148M AAV8 adeno-associated virus via tail vein. 11 vg. hPNPLA3 148M AAV8 at 5×10 11 The titer is provided in vg / ml, and the administration volume is 200μL / animal. Fourteen days after modeling, two groups of mice were administered test conjugates 11 and 13 subcutaneously at a dose of 9 mg / kg (based on siRNA). The siRNA conjugates were provided as a 0.9% sodium chloride aqueous solution containing 1.8 mg / mL of the siRNA conjugate, with an administration volume of 5 mL / kg for both groups. Two other groups of mice were administered test conjugates 11 and 13 subcutaneously at a dose of 3 mg / kg (based on siRNA). The siRNA conjugates were provided as a 0.9% sodium chloride aqueous solution containing 0.6 mg / mL of the siRNA conjugate, with an administration volume of 5 mL / kg for both groups. One group of mice was given 1×PBS at a volume of 5 mL / kg as the control group. Using the drug administration point as Day 1, five animals in the PBS group were sacrificed before D1 administration, and liver tissue from each mouse was collected and preserved using RNA later (Sigma Aldrich). On days 15, 29, and 43 post-administration, five animals in each group were sacrificed, and liver tissue was collected and preserved using RNA later (Sigma Aldrich). Liver tissue was homogenized using a tissue homogenizer, and total RNA was extracted using Trizol (Sigma Aldrich) according to the manufacturer's instructions. Following the procedure in Example 2, the inhibitory activity of PNPLA3 148M mRNA was measured and calculated. The results are shown in Table 10. Table 10 Inhibition rate of hPNPLA3 148M mRNA in mice According to the results in Table 10, all conjugates and dosage combinations showed sustained inhibitory effects during the experiment, which strongly demonstrates the potential of the conjugates to have a long-lasting inhibitory effect on hPNPLA3 148M mRNA. Inhibitory activity of the conjugate in AAV-hPNPLA3 148M mice in Experiment Example 7 Using the same method as in Example 6, the inhibitory efficiency of conjugate 13 on hPNPLA3 148M mRNA expression in AAV-hPNPLA3 148M mice was determined, except that mice were administered conjugate 13 at doses of 1 mg / kg and 3 mg / kg (both calculated as siRNA), respectively. The inhibition rate of hPNPLA3 mRNA in mouse liver tissue was measured on days 15, 29, and 43 post-administration. Following the procedure in Example 2, the inhibitory activity of hPNPLA3 148M mRNA was measured and calculated. The results are shown in Table 11. Table 11 Inhibition rate of hPNPLA3 148M mRNA in mice According to the results in Table 11, the dose of the conjugate was positively correlated with the inhibitory effect, and the inhibition rate of the 3 mg / kg group was higher than that of the 1 mg / kg group at all time points. Throughout the experiment, the 1 mg / kg dose group maintained an inhibition rate of 57.6% at D43, while the 3 mg / kg dose group reached 73.0%, both showing sustained inhibitory effects, indicating that conjugate 13 has long-term inhibitory potential. Some embodiments of this disclosure have been described in detail above. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure. It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately. Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A single-stranded oligonucleotide having a length of 16-30 nucleotides, wherein the composition of the single-stranded oligonucleotide enables it to inhibit the expression of PNPLA3 mRNA via an RNAi mechanism; wherein each nucleotide in the single-stranded oligonucleotide is independently modified or unmodified, wherein, In the single-stranded oligonucleotide, at least one nucleotide is nucleotide X, and at least one nucleotide is a fluorinated nucleotide. Furthermore, in the 5'-3' direction, the 13th nucleotide of the single-stranded oligonucleotide is a substituted alkoxy-modified nucleotide; the 14th nucleotide of the single-stranded oligonucleotide is nucleotide X; and each of the 15th nucleotide and all subsequent nucleotides of the single-stranded oligonucleotide is independently a modified nucleotide. Each nucleotide X is independently a deoxynucleotide or an unmodified nucleotide.

2. The single-chain oligonucleotide as described in claim 1, wherein, The single-chain oligonucleotide has a length of 17-28, 19-27, or 20-25 nucleotides; or, the single-chain oligonucleotide has a length of 19, 21, or 23 nucleotides.

3. The single-stranded oligonucleotide as described in claim 1 or 2, wherein, The number of nucleotides X is 1-3.

4. The single-chain oligonucleotide according to any one of claims 1-3, wherein, In the single-stranded oligonucleotide, the 12th and 14th nucleotides are each independently nucleotide X in the 5'-3' orientation; or, only the 14th nucleotide is nucleotide X.

5. The single-stranded oligonucleotide according to any one of claims 1-4, wherein, The number of unmodified nucleotides does not exceed 5, 4, 3, 2, or 1; or, each of the nucleotides in the single-stranded oligonucleotide is independently modified.

6. The single-chain oligonucleotide according to any one of claims 1-5, wherein, The number of fluorinated nucleotides is 2-7.

7. The single-stranded oligonucleotide according to any one of claims 1-6, wherein, In the 5'-3' orientation, fluorinated nucleotides refer to 2-5 of the 2nd, 5th, 6th, 7th, 12th, 16th, 18th and 19th nucleotides in the single-stranded oligonucleotide.

8. The single-chain oligonucleotide of claim 7, wherein, In the 5'-3' direction, fluorinated nucleotides refer to one or two of the 2nd and 12th nucleotides, one or two of the 5th-7th nucleotides, and 0-2 of the 16th-19th nucleotides in the single-stranded oligonucleotide; Alternatively, in the 5'-3' orientation, the fluorinated nucleotide refers to the 2nd and 6th nucleotides of the single-stranded oligonucleotide; the 2nd, 6th and 16th nucleotides; the 2nd, 5th, 7th, 12th and 16th nucleotides; the 2nd, 7th, 12th, 16th and 19th nucleotides; or the 2nd, 6th, 12th, 16th and 19th nucleotides.

9. The single-chain oligonucleotide of claim 8, wherein, In the single-stranded oligonucleotide, except for the 13th and 14th nucleotides in the 5'-3' orientation and the fluorinated nucleotides, each modified nucleotide is independently selected from one of alkoxy-modified nucleotides, substituted alkoxy-modified nucleotides, alkyl-modified nucleotides, substituted alkyl-modified nucleotides, amine-modified nucleotides, heat-labile nucleotides, and BNA.

10. The single-chain oligonucleotide of claim 9, wherein, Except for the 13th and 14th nucleotides in the 5'-3' orientation and fluorinated nucleotides, each modified nucleotide is independently selected from alkoxy-modified nucleotides, substituted alkoxy-modified nucleotides, or heat-labile nucleotides, and the number of substituted alkoxy-modified nucleotides does not exceed 3 and the number of heat-labile nucleotides does not exceed 2.

11. The single-chain oligonucleotide of claim 10, wherein, The single-stranded oligonucleotide is 19-23 nucleotides in length, and In the 5'-3' orientation, the 13th nucleotide is a substituted alkoxy-modified nucleotide, the 14th nucleotide is nucleotide X, one of the 5th-7th nucleotides, as well as the 2nd and 16th nucleotides of the single-stranded oligonucleotide, are fluorinated nucleotides, the 3rd nucleotide is an alkoxy-modified nucleotide or a substituted alkoxy-modified nucleotide, and the 5th nucleotide, if not a fluorinated nucleotide, is an alkoxy-modified nucleotide or a substituted alkoxy-modified nucleotide, and each of the remaining nucleotides in the single-stranded oligonucleotide is independently an alkoxy-modified nucleotide.

12. The single-stranded oligonucleotide of claim 11, wherein, The single-stranded oligonucleotide is 21 nucleotides in length, and In the 5'-3' orientation, the 13th nucleotide is a substituted alkoxy-modified nucleotide, the 14th nucleotide is nucleotide X, the 2nd, 6th and 16th nucleotides are fluorinated nucleotides, the 3rd or 5th nucleotide is an alkoxy-modified nucleotide or a substituted alkoxy-modified nucleotide, and each of the remaining nucleotides in the single-stranded oligonucleotide is independently an alkoxy-modified nucleotide.

13. The single-chain oligonucleotide according to any one of claims 9-12, wherein, Each nucleotide X refers to a deoxynucleotide; Each alkoxy-modified nucleotide is a alkoxy-modified nucleotide; Each substituted alkoxy-modified nucleotide refers to a nucleotide modified with 2'-O-methoxyethyl; and / or Each thermally unstable nucleotide refers to GNA.

14. The single-stranded oligonucleotide according to any one of claims 1-13, wherein, Each of at least two of the linking groups between adjacent nucleotides in the single-stranded oligonucleotide is independently a phosphate ester group with a modifying group.

15. The single-stranded oligonucleotide of claim 14, wherein, Each of 1-4 linking groups between adjacent nucleotides in the 5' end of the single-stranded oligonucleotide, and / or each of 1-4 linking groups between adjacent nucleotides in the 3' end of the single-stranded oligonucleotide, is independently a phosphate ester group with a modifying group; and / or if unmodified nucleotides are present in the single-stranded oligonucleotide, each of 1 or all 2 linking groups between each unmodified nucleotide and its adjacent nucleotide is independently a phosphate ester group with a modifying group; and / or In the single-stranded oligonucleotide, each of 2-6, or 3 or 4 of the linking groups between adjacent nucleotides is an independently phosphate ester group with a modifying group.

16. The single-stranded oligonucleotide of claim 14 or 15, wherein, Each of the linking groups between adjacent nucleotides in the 5' end of the first to third nucleotides of the single-stranded oligonucleotide, and each of the linking groups between adjacent nucleotides in the 3' end of the first to third nucleotides, is independently a phosphate ester group with a modifying group; and / or if there are unmodified nucleotides in the single-stranded oligonucleotide, each of the two linking groups between each unmodified nucleotide and its adjacent nucleotide is independently a phosphate ester group with a modifying group.

17. The single-stranded oligonucleotide according to any one of claims 14-16, wherein, Each phosphate group with a modifying group is independently a thiophosphate group having the structure shown in formula (28):

18. The single-stranded oligonucleotide according to any one of claims 1-17, wherein, The 5' terminal nucleotide of the single-stranded oligonucleotide is a 5'-hydroxynucleotide, a 5'-phosphate nucleotide, or a 5'-phosphate analog modified nucleotide, wherein the 5'-hydroxynucleotide has the structure shown in formula (29); the 5'-phosphate nucleotide has the structure shown in formula (30); and the 5'-phosphate analog modified nucleotide is selected from one of the nucleotides shown in formulas (31) to (34). R is selected from H, OH, OCH3 and F; Base represents a nucleic acid base, selected from A, U, C, G or T.

19. The single-stranded oligonucleotide according to any one of claims 1-18, wherein, The single-stranded oligonucleotide is substantially anticomplementary, substantially anticomplementary, or completely anticomplementary to a continuous nucleotide sequence m in PNPLA3 mRNA; the length of the nucleotide sequence m is not greater than the length of the single-stranded oligonucleotide, and the length of the nucleotide sequence m is the same as the length of the single-stranded oligonucleotide, or differs by no more than 8 nucleotides, or differs by 1-5 nucleotides. Alternatively, the length of the nucleotide sequence m is at least 16 nucleotides, or 16-25 nucleotides, or 18-23 nucleotides, or 19-21 nucleotides; Alternatively, the single-stranded oligonucleotide has the same length as the nucleotide sequence m, and at least the nucleotide sequence of the single-stranded oligonucleotide other than the terminal nucleotide is completely anticomplementary to the nucleotide sequence m; Alternatively, in the 5'-3' direction, the nucleotide sequence other than position 1 of the single-stranded oligonucleotide is completely anticomplementary to the nucleotide sequence m; or all nucleotides of the single-stranded oligonucleotide are completely anticomplementary to the nucleotide sequence m.

20. The single-stranded oligonucleotide according to any one of claims 1-19, wherein, The single-stranded oligonucleotide contains nucleotide sequence II, which is identical to any one of the nucleotide sequences shown in SEQ ID NO:9-SEQ ID NO:16 and SEQ ID NO:67 in at least 16, at least 17, at least 18, at least 19, at least 20 or 21 consecutive nucleotides, and the consecutive identical nucleotides include no more than 3 base differences.

21. The single-chain oligonucleotide of claim 20, wherein, The nucleotide sequence II has a base difference of no more than one or no base difference between the first to 19th nucleotide sequences shown in any one of SEQ ID NO:9-SEQ ID NO:16 and SEQ ID NO:67; or, the nucleotide sequence II is any one of SEQ ID NO:9-SEQ ID NO:16 and SEQ ID NO:

67.

22. The single-stranded oligonucleotide of claim 20 or 21, wherein, The single-stranded oligonucleotide also contains a nucleotide sequence IV, which is attached to the 3' end of the nucleotide sequence II and has a length of 1, 2, 3, or 4 nucleotides. Each nucleotide in the nucleotide sequence IV is independently one of the non-fluorinated modified nucleotides. The nucleotide sequence IV is substantially anticomplementary or completely anticomplementary to the PNPLA3 mRNA. Each of the non-fluorinated modified nucleotides is independently selected from one of the following: 2'-methoxy modified nucleotides, 2'-alkyl modified nucleotides with 1-3 carbon atoms, 2'-amino modified nucleotides, 2'-substituted amino modified nucleotides, and heat-labile nucleotides. Alternatively, the length of the nucleotide sequence IV is 2 nucleotides.

23. The single-chain oligonucleotide according to any one of claims 20-22, wherein, The single-stranded oligonucleotide also contains a nucleotide sequence V, each nucleotide of which is independently a non-fluorinated nucleotide, the length of which is 1 to 3 nucleotides, and is attached to the 3' end of either nucleotide sequence IV or nucleotide sequence II. After the single-stranded oligonucleotide forms a double-stranded oligonucleotide with the sense strand, the nucleotide sequence V constitutes the 3' overhang of the double-stranded oligonucleotide. Alternatively, the nucleotide sequence V is 2 nucleotides in length and, in the 5'-3' direction, is two consecutive thymine deoxynucleotides, two consecutive uracil nucleotides, or is completely reverse complementary to PNPLA3 mRNA; Alternatively, the single-chain oligonucleotide is the antisense strand shown in SEQ ID NO:52, SEQ ID NO:54, SEQ ID NO:56, SEQ ID NO:58, SEQ ID NO:60, SEQ ID NO:62, SEQ ID NO:64, SEQ ID NO:66 or SEQ ID NO:68; Alternatively, the single-chain oligonucleotide is the antisense strand shown in SEQ ID NO:18, SEQ ID NO:20, SEQ ID NO:22, SEQ ID NO:24, SEQ ID NO:26, SEQ ID NO:28, SEQ ID NO:30, SEQ ID NO:32, SEQ ID NO:34, SEQ ID NO:36, SEQ ID NO:38, SEQ ID NO:40, or SEQ ID NO:

42.

24. A double-stranded oligonucleotide comprising a sense strand and an antisense strand, each nucleotide in the sense strand being a modified or unmodified nucleotide, wherein the sense strand and the antisense strand are at least partially anticomplementary to form a double-stranded region, wherein, The antisense strand is a single-stranded oligonucleotide as described in any one of claims 1-23.

25. The double-stranded oligonucleotide of claim 24, wherein, The length of the positive chain is 15-26, 17-24, or 19-23 nucleotides; Alternatively, the length of the justice chain is 19-21 nucleotides.

26. The double-stranded oligonucleotide of claim 25, wherein, The length difference between the sense and antisense strands is 0-5 nucleotides. Alternatively, the length of the justice chain is not greater than the length of the antisense chain; Alternatively, the sense and antisense strands may be of the same length, either 19, 20, or 21 nucleotides. Alternatively, the length of the sense strand is 19-21 nucleotides, the length of the antisense strand is 20-24 nucleotides, and the length of the antisense strand is 1-3 nucleotides longer than the length of the sense strand; or the length of the antisense strand is 2 nucleotides longer than the length of the sense strand. Alternatively, the length of the sense strand is 19 nucleotides and the length of the antisense strand is 21 nucleotides; or the length of the sense strand is 21 nucleotides and the length of the antisense strand is 21 nucleotides; or the length of the sense strand is 21 nucleotides and the length of the antisense strand is 23 nucleotides.

27. The double-stranded oligonucleotide according to any one of claims 24-26, wherein, In the 3'-5' orientation, 2-3 of the 11th-13th nucleotides of the positive strand are fluorinated nucleotides, the first and / or last nucleotide is an alkoxylated nucleotide or a reverse debased deoxynucleotide, and the remaining nucleotides in the positive strand are each independently non-fluorinated nucleotides, each of which is independently selected from alkoxylated nucleotides, alkylated nucleotides, amine-modified nucleotides, and heat-labile nucleotides.

28. The double-stranded oligonucleotide of claim 27, wherein, In the 3'-5' direction, the 11th and 13th nucleotides, or the 11th-13th nucleotides, of the positive strand are fluorinated nucleotides, the 1st and / or the last nucleotide is a reverse debased deoxynucleotide, and the nucleotides at the remaining positions of the positive strand are each independently alkoxylated nucleotides.

29. The double-stranded oligonucleotide of claim 27 or 28, wherein, Each of the alkoxy-modified nucleotides is independently a methoxy-modified nucleotide.

30. The double-stranded oligonucleotide according to any one of claims 24-29, wherein, In the positive strand, each of at least one of the linking groups connecting two adjacent nucleotides is independently a phosphate group with a modifying group, the phosphate group with the modifying group being present at least once between two adjacent nucleotides in the first to fifth nucleotides at the 5' end of the positive strand and between two adjacent nucleotides in the first to fifth nucleotides at the 3' end.

31. The double-stranded oligonucleotide of claim 30, wherein, One to four, or all four, of the linking groups connecting any two adjacent nucleotides from the first to the fifth nucleotide at the 5' end of the positive strand are independently phosphate groups with a modifying group; and / or, one to four, or all four, of the linking groups connecting any two adjacent nucleotides from the first to the fifth nucleotide at the 3' end of the positive strand are independently phosphate groups with a modifying group; or, each phosphate group with a modifying group is independently a thiophosphate group having the structure shown in formula (28).

32. The double-stranded oligonucleotide according to any one of claims 24-31, wherein, The sense strand contains 19-21 nucleotides, and the antisense strand contains 21-23 nucleotides; In the positive chain, the 11th and 13th nucleotides, or the 11th to 13th nucleotides, are fluorinated nucleotides in the 3'-5' direction, the 1st and / or the last nucleotide is a methoxylated nucleotide or a reverse debased deoxynucleotide, and the nucleotides at the remaining positions are each independently methoxylated nucleotides. Each of 1-4 of the linking groups between adjacent nucleotides in the 1st-5th nucleotides at the 5' end of the positive strand, and / or 1-4 of the linking groups between adjacent nucleotides in the 1st-5th nucleotides at the 3' end of the positive strand, is an independently phosphate thioester group; Alternatively, the justice chain is the justice chain shown in SEQ ID NO:51, SEQ ID NO:53, SEQ ID NO:55, SEQ ID NO:57, SEQ ID NO:59, SEQ ID NO:61, SEQ ID NO:63 or SEQ ID NO:65; Alternatively, the justice chain is the justice chain shown in SEQ ID NO:17, SEQ ID NO:19, SEQ ID NO:21, SEQ ID NO:23, SEQ ID NO:25, SEQ ID NO:27, SEQ ID NO:29, SEQ ID NO:31, SEQ ID NO:33, SEQ ID NO:35, SEQ ID NO:37, SEQ ID NO:39 or SEQ ID NO:

41.

33. The double-stranded oligonucleotide of claim 32, wherein, The sense strand contains 19 nucleotides, and the antisense strand contains 21 nucleotides; In the positive strand, the 11th and 13th nucleotides, or the 11th to 13th nucleotides, are fluorinated nucleotides in the 3'-5' direction; the 1st and / or the last nucleotide is a reverse debased deoxynucleotide; and the nucleotides at the remaining positions are each independently methoxylated nucleotides. In the positive strand, 1-4 of the linking groups between adjacent nucleotides in the 1st to 5th nucleotides at the 5' end, and / or 1-4 of the linking groups between adjacent nucleotides in the 1st to 5th nucleotides at the 3' end, are each independently a phosphate thioester group. In the antisense strand, in the 5'-3' direction, the 13th nucleotide is a 2'-O-methoxyethyl modified nucleotide, the 14th nucleotide is a deoxynucleotide, and the 2nd, 6th and 16th nucleotides are fluorinated modified nucleotides. Each of the remaining nucleotides in the antisense strand is independently an alkoxy modified nucleotide. The linking groups between any two adjacent nucleotides in the 5' end of the first to third nucleotides of the antisense strand, and between any two adjacent nucleotides in the 3' end of the first to third nucleotides, are each independently a phosphate ester group with a modified group; and if unmodified nucleotides are present, each of the two linking groups between each unmodified nucleotide and its adjacent nucleotides is independently a phosphate ester group with a modified group; and The 5' terminal nucleotide of the antisense strand is a 5'-hydroxy nucleotide as shown in formula (29) or a nucleotide modified with 5'-vinyl phosphate as shown in formula (31).

34. The double-stranded oligonucleotide according to any one of claims 24-33, wherein, The justice chain and the antisense chain are essentially opposite complementary, substantially opposite complementary, or completely opposite complementary. Alternatively, in the 5'-3' direction, at least the nucleotide sequence other than the first and last positions of the sense strand is substantially anticomplementary or completely anticomplementary to the antisense strand; Alternatively, in the 5'-3' direction, the nucleotide sequence of the sense strand except the last nucleotide is completely anticomplementary to the antisense strand; or all nucleotides of the sense strand are completely anticomplementary to the antisense strand. Alternatively, the unmodified equivalent sequence of the positive strand may contain a nucleotide sequence of the same length as nucleotide sequence m, and differing by no more than 3 bases, no more than 1 base, or having no base difference, wherein nucleotide sequence m is a continuous nucleotide sequence in PNPLA3 mRNA, and the length of nucleotide sequence m is at least 16 nucleotides, or 16-25 nucleotides, or 18-23 nucleotides, or 19-21 nucleotides.

35. The double-stranded oligonucleotide of claim 34, wherein, The double-stranded oligonucleotide is siRNA.

36. The double-stranded oligonucleotide according to any one of claims 24-35, wherein, The sense strand contains nucleotide sequence I, and the antisense strand contains nucleotide sequence II. Sequence I is identical to any one of the nucleotide sequences shown in SEQ ID NO:1-SEQ ID NO:8 for at least 16, at least 17, at least 18, at least 19, at least 20, or 21 consecutive nucleotides, and there are no more than 3 base differences therein. The sequence II is identical to any one of the nucleotide sequences shown in SEQ ID NO:9-SEQ ID NO:16 and SEQ ID NO:67 for at least 16, at least 17, at least 18, at least 19, at least 20 or 21 consecutive nucleotides, and there are no more than 3 base differences therein.

37. The double-stranded oligonucleotide of claim 36, wherein, Nucleotide sequence I differs from the nucleotide sequences shown in SEQ ID NO:1-8 by no more than one base, and nucleotide sequence II differs from the 1st to 19th bases of the nucleotide sequences shown in SEQ ID NO:9-16 by no more than one base; or, the unmodified equivalent sequence of the double-stranded oligonucleotide is any one of siRNA1-siRNA9, wherein the sense strand of siRNA1 is the sequence shown in SEQ ID NO:1, and the antisense strand is the sequence shown in SEQ ID NO:2; the sense strand of siRNA2 is the sequence shown in SEQ ID NO:3, and the antisense strand is the sequence shown in SEQ ID NO:4; the sense strand of siRNA3 is the sequence shown in SEQ ID NO:5, and the antisense strand is the sequence shown in SEQ ID NO:6; the sense strand of siRNA4 is the sequence shown in SEQ ID NO:7, and the antisense strand is the sequence shown in SEQ ID NO:8; the sense strand of siRNA5 is the sequence shown in SEQ ID NO:9, and the antisense strand is the sequence shown in SEQ ID NO:10; the sense strand of siRNA6 is the sequence shown in SEQ ID NO:11, and the antisense strand is the sequence shown in SEQ ID NO:

8. The sequence shown in NO:12; the sense strand of siRNA7 is shown in SEQ ID NO:13, and the antisense strand is shown in SEQ ID NO:14; the sense strand of siRNA8 is shown in SEQ ID NO:15, and the antisense strand is shown in SEQ ID NO:16; the sense strand of siRNA9 is shown in SEQ ID NO:2, and the antisense strand is shown in SEQ ID NO:

67.

38. The double-stranded oligonucleotide of claim 37, wherein, The double-stranded oligonucleotide is any one of siRNA1-M1-siRNA9-M1, wherein the sense strand of siRNA1-M1 is the sequence shown in SEQ ID NO:51, and the antisense strand is the sequence shown in SEQ ID NO:52; the sense strand of siRNA2-M1 is the sequence shown in SEQ ID NO:53, and the antisense strand is the sequence shown in SEQ ID NO:54; the sense strand of siRNA3-M1 is the sequence shown in SEQ ID NO:55, and the antisense strand is the sequence shown in SEQ ID NO:56; the sense strand of siRNA4-M1 is the sequence shown in SEQ ID NO:57, and the antisense strand is the sequence shown in SEQ ID NO:58; the sense strand of siRNA5-M1 is the sequence shown in SEQ ID NO:59, and the antisense strand is the sequence shown in SEQ ID NO:60; the sense strand of siRNA6-M1 is the sequence shown in SEQ ID NO:61, and the antisense strand is the sequence shown in SEQ ID NO:62; the sense strand of siRNA7-M1 is the sequence shown in SEQ ID NO:63, and the antisense strand is the sequence shown in SEQ ID NO:

64. The sequence shown in NO:64; the sense strand of siRNA8-M1 is the sequence shown in SEQ ID NO:65, and the antisense strand is the sequence shown in SEQ ID NO:66; the sense strand of siRNA9-M1 is the sequence shown in SEQ ID NO:53, and the antisense strand is the sequence shown in SEQ ID NO:

68. Alternatively, the double-stranded oligonucleotide comprises a sense strand and an antisense strand in any one of conjugates 1-13, wherein the sense strand of conjugate 1 is the sequence shown in SEQ ID NO:17 and the antisense strand is the sequence shown in SEQ ID NO:18; the sense strand of conjugate 2 is the sequence shown in SEQ ID NO:19 and the antisense strand is the sequence shown in SEQ ID NO:20; the sense strand of conjugate 3 is the sequence shown in SEQ ID NO:21 and the antisense strand is the sequence shown in SEQ ID NO:22; the sense strand of conjugate 4 is the sequence shown in SEQ ID NO:23 and the antisense strand is the sequence shown in SEQ ID NO:24; the sense strand of conjugate 5 is the sequence shown in SEQ ID NO:25 and the antisense strand is the sequence shown in SEQ ID NO:26; the sense strand of conjugate 6 is the sequence shown in SEQ ID NO:27 and the antisense strand is the sequence shown in SEQ ID NO:28; the sense strand of conjugate 7 is the sequence shown in SEQ ID NO:29 and the antisense strand is the sequence shown in SEQ ID NO:30; and the sense strand of conjugate 8 is the sequence shown in SEQ ID NO:

29. The sequence shown in SEQ ID NO:31 is the positive strand of conjugate 9, and the sequence shown in SEQ ID NO:32 is the negative strand of conjugate 10; the sequence shown in SEQ ID NO:33 is the positive strand of conjugate 10, and the sequence shown in SEQ ID NO:36 is the negative strand of conjugate 11; the sequence shown in SEQ ID NO:37 is the positive strand of conjugate 11, and the sequence shown in SEQ ID NO:38 is the negative strand of conjugate 12; the sequence shown in SEQ ID NO:39 is the positive strand of conjugate 12, and the sequence shown in SEQ ID NO:40 is the negative strand of conjugate 13; the sequence shown in SEQ ID NO:41 is the positive strand of conjugate 13, and the sequence shown in SEQ ID NO:42 is the negative strand of conjugate 13.

39. An oligonucleotide conjugate comprising an oligonucleotide group and a delivery group conjugated to the oligonucleotide group, wherein the oligonucleotide group is independently formed by removing one or more atoms or groups from a single-stranded oligonucleotide as described in any one of claims 1-23 or a double-stranded oligonucleotide as described in any one of claims 24-38.

40. The oligonucleotide conjugate of claim 39, wherein, The delivery group comprises a linker group and a pharmaceutically acceptable target group, and the single-stranded or double-stranded oligonucleotide group, the linker group and the target group are covalently or non-covalently linked in sequence, each of the target groups being selected from ligands capable of binding to desialylate glycoprotein receptors on the surface of mammalian hepatocytes; Alternatively, the oligonucleotide conjugate may contain an oligonucleotide group that is an siRNA group formed from siRNA1-siRNA9; Alternatively, the double-stranded oligonucleotide group contained in the oligonucleotide conjugate is an siRNA group formed from any one of the following siRNAs: siRNA1-M1, siRNA2-M1, siRNA3-M1, siRNA4-M1, siRNA5-M1, siRNA6-M1, siRNA7-M1, siRNA8-M1, and siRNA9-M1. Alternatively, the oligonucleotide conjugate has the structure shown in formula (403). In formula (403), Nu is an oligonucleotide group; or, the oligonucleotide group is a double-stranded oligonucleotide group, and the P atom is covalently linked to the 3' terminal nucleotide of the positive strand of the double-stranded oligonucleotide group; or, the 3' terminal nucleotide of the positive strand of the double-stranded oligonucleotide group is a reverse debased deoxynucleotide, and the P atom is covalently linked to the double-stranded oligonucleotide group by substituting the hydrogen atom in the hydroxyl group of the debased reverse deoxynucleotide at the 3' terminal of the positive strand of the double-stranded oligonucleotide group via the methylene group linked to the ribose ring. Alternatively, the oligonucleotide conjugate is one of conjugate 1 to conjugate 13.

41. A pharmaceutically acceptable salt of a single-stranded oligonucleotide as described in any one of claims 1-23, a double-stranded oligonucleotide as described in any one of claims 24-38, or an oligonucleotide conjugate as described in claim 39 or 40; Alternatively, the pharmaceutically acceptable salt is a partial or complete water-soluble salt of the single-stranded oligonucleotide, the double-stranded oligonucleotide, or the oligonucleotide conjugate. Alternatively, the water-soluble salt is one or more of an amine salt, an alkali metal salt, or an alkaline earth metal salt; Alternatively, the amine salt is selected from one or more of ammonium salts, methylamine salts, tertiary amine salts, and quaternary ammonium salts, and the alkali metal salt is selected from potassium salts or sodium salts, and the alkaline earth metal salt is selected from calcium salts or magnesium salts; Alternatively, the tertiary amine salt is one or more of triethylamine salt, triisopropylamine salt, or N,N-diisopropylethylamine salt; Alternatively, the pharmaceutically acceptable salt is a salt or a portion of the single-stranded oligonucleotide, the double-stranded oligonucleotide, or the oligonucleotide conjugate, wherein the salt is one or more of a methylamine salt, a triethylamine salt, or a sodium salt.

42. A pharmaceutical composition comprising one or more of the following: a single-stranded oligonucleotide as claimed in any one of claims 1-23, a double-stranded oligonucleotide as claimed in any one of claims 24-38, an oligonucleotide conjugate as claimed in claim 39 or 40, and a pharmaceutically acceptable salt as claimed in claim 41, and a pharmaceutically acceptable excipient; Alternatively, the pharmaceutically acceptable excipient is one or more of solvents, preservatives, osmotic pressure regulators, and other pharmaceutically acceptable carriers; Alternatively, the solvent is one of deionized water, water for injection, pH buffer, physiological saline, ethanol, or an aqueous solution of ethanol.

43. Use of one or more of the single-stranded oligonucleotide of any one of claims 1-23, the double-stranded oligonucleotide of any one of claims 24-38, the oligonucleotide conjugate of claim 39 or 40, the pharmaceutically acceptable salt of claim 41, and the pharmaceutical composition of claim 42 in the preparation of a medicament for treating and / or preventing diseases or symptoms associated with PNPLA3 mRNA levels.

44. The use as described in claim 43, wherein, The disease or symptom associated with PNPLA3 mRNA levels is MAFLD; or, the disease or symptom associated with PNPLA3 mRNA levels is MASH.

45. A method for treating and / or preventing diseases or symptoms associated with PNPLA3 mRNA levels, the method comprising administering to a subject in need an effective amount of one or more of the following: a single-stranded oligonucleotide of any one of claims 1-23, a double-stranded oligonucleotide of any one of claims 24-38, an oligonucleotide conjugate of claim 39 or 40, a pharmaceutically acceptable salt of claim 41, and a pharmaceutical composition of claim 42.

46. ​​A method for regulating the expression level of the PNPLA3 gene in cells, the method comprising contacting the cells with an effective amount of one or more of the single-stranded oligonucleotide of any one of claims 1-23, the double-stranded oligonucleotide of any one of claims 24-38, the oligonucleotide conjugate of claim 39 or 40, the pharmaceutically acceptable salt of claim 41, and the pharmaceutical composition of claim 42.

47. One or more of the following as used as a medicament: the single-stranded oligonucleotide of any one of claims 1-23, the double-stranded oligonucleotide of any one of claims 24-38, the oligonucleotide conjugate of claim 39 or 40, the pharmaceutically acceptable salt of claim 41, and the pharmaceutical composition of claim 42.

48. A cell expressing PNPLA3 mRNA, and the cell comprising one or more of the following: a single-stranded oligonucleotide of any one of claims 1-23, a double-stranded oligonucleotide of any one of claims 24-38, an oligonucleotide conjugate of claim 39 or 40, a pharmaceutically acceptable salt of claim 41, and a pharmaceutical composition of claim 42.

49. A kit comprising one or more of the following: a single-stranded oligonucleotide as described in any one of claims 1-23; a double-stranded oligonucleotide as described in any one of claims 24-38; an oligonucleotide conjugate as described in claim 39 or 40; a pharmaceutically acceptable salt as described in claim 41; and a pharmaceutical composition as described in claim 42.

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