Polynucleotide nanostructures

Abstract

Provided are polynucleotide origami nanostructures comprising polynucleotides with complementarity to at least two additional polynucleotides that comprise the nanostructures. Pharmaceutical compositions comprising the nanostructures and methods of silencing target mRNAs in a subject are further disclosed.

Description

[0001] POLYNUCLEOTIDE NANOSTRUCTURES CROSS REFERENCE TO RELATED APPLICATION This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 680,307, filed August 7, 2024. The entire content of the above-referenced patent application is incorporated by reference in its entirety herein. BACKGROUND Delivery of therapeutic oligonucleotides to specific tissues, and the effective and prolonged silencing of target mRNA in said tissues remains a challenge in the field of oligonucleotide therapeutics. Moreover, it may be advantageous to silence multiple different mRNA in a target cell in a tissue, however, multi-mRNA targeting options for therapeutic oligonucleotides are also lacking. Accordingly, there is a need in the art for effective therapeutic oligonucleotide delivery and silencing modalities. SUMMARY In one aspect, the disclosure provides a polynucleotide nanostructure comprising X total polynucleotide strands of Formula I: wherein: X corresponds to an integer of at least 3 (e.g., 3-15); n corresponds to an individual polynucleotide strand of the polynucleotide nanostructure of X total polynucleotide strands; corresponds to an antisense compound; corresponds to a region of complementarity to the antisense compound in the individual polynucleotide strand; corresponds to a region of complementarity to individual polynucleotide strand of n-1 in the individual polynucleotide strand of n; corresponds to a polynucleotide scaffold portion of the individual polynucleotide strand; and corresponds to a region of complementarity to individual polynucleotide strand of n+1 in in the individual polynucleotide strand of n; wherein individual polynucleotide strand of n = 1 (i.e., the first polynucleotide strand) and individual polynucleotide strand of n = X (i.e., the last polynucleotide strand) each comprise a region of complementarity to each other; corresponds to Linker 1, optionally wherein Linker 1 is absent; and corresponds to Linker 2, optionally wherein Linker 2 is absent. In certain embodiments, X is 3-15. In certain embodiments, X is 3. In certain embodiments, X is 4. In certain embodiments, X is 5. In certain embodiments, X is 6. In certain embodiments, X is 7. In certain embodiments, X is 8. In certain embodiments, X is 9. In certain embodiments, X is 10. In certain embodiments, X is 11. In certain embodiments, X is 12. In certain embodiments, X is 13. In certain embodiments, X is 14. In certain embodiments, X is 15. In certain embodiments, each individual polynucleotide strand is between 20 nucleotides and 120 nucleotides in length. In certain embodiments, each individual polynucleotide strand is between 40-120 nucleotides, 40-100 nucleotides, 40-80 nucleotides, 40-60 nucleotides, 60-120 nucleotides, 60- 100 nucleotides, or 60-80 nucleotides. In certain embodiments, the region of complementarity to the antisense compound in the individual polynucleotide strand (i.e., ) is between 4 nucleotides to 40 nucleotides in length. In certain embodiments, the region of complementarity to the antisense compound in the individual polynucleotide strand (i.e., ) is 4 nucleotides in length, 5 nucleotides in length, 6 nucleotides in length, 7 nucleotides in length, 8 nucleotides in length, 9 nucleotides in length, 10 nucleotides in length, 11 nucleotides in length, 12 nucleotides in length, 13 nucleotides in length, 14 nucleotides in length, 15 nucleotides in length, 16 nucleotides in length, 17 nucleotides in length, 18 nucleotides in length, 19 nucleotides in length, 20 nucleotides in length, 21 nucleotides in length, 22 nucleotides in length, 23 nucleotides in length, 24 nucleotides in length, or 25 nucleotides in length. In certain embodiments, the region of complementarity between individual polynucleotide strands is between 4 nucleotides to 40 nucleotides in length. In certain embodiments, the region of complementarity between individual polynucleotide strands is 4 nucleotides in length, 5 nucleotides in length, 6 nucleotides in length, 7 nucleotides in length, 8 nucleotides in length, 9 nucleotides in length, 10 nucleotides in length, 11 nucleotides in length, 12 nucleotides in length, 13 nucleotides in length, 14 nucleotides in length, 15 nucleotides in length, 16 nucleotides in length, 17 nucleotides in length, 18 nucleotides in length, 19 nucleotides in length, 20 nucleotides in length, 21 nucleotides in length, 22 nucleotides in length, 23 nucleotides in length, 24 nucleotides in length, or 25 nucleotides in length. In certain embodiments, the region of complementarity between in an individual polynucleotide strand (e.g., n = 1) and in an adjacent individual polynucleotide strand (n = 2) is between 4 nucleotides to 40 nucleotides in length. In certain embodiments, the polynucleotide scaffold portion of the individual polynucleotide strand is between 4 nucleotides to 40 nucleotides in length. In certain embodiments, the polynucleotide scaffold portion of the individual polynucleotide strand is 4 nucleotides in length, 5 nucleotides in length, 6 nucleotides in length, 7 nucleotides in length, 8 nucleotides in length, 9 nucleotides in length, 10 nucleotides in length, 11 nucleotides in length, 12 nucleotides in length, 13 nucleotides in length, 14 nucleotides in length, 15 nucleotides in length, 16 nucleotides in length, 17 nucleotides in length, 18 nucleotides in length, 19 nucleotides in length, 20 nucleotides in length, 21 nucleotides in length, 22 nucleotides in length, 23 nucleotides in length, 24 nucleotides in length, 25 nucleotides in length, 26 nucleotides in length, 27 nucleotides in length, 28 nucleotides in length, 29 nucleotides in length, or 30 nucleotides in length. In certain embodiments, i) the region of complementarity to the antisense compound, ii) the region of complementarity between individual polynucleotide strands, and iii) the polynucleotide scaffold portion of the individual polynucleotide strand, are identical nucleotides in length. In certain embodiments, each antisense compound of each individual polynucleotide strand is identical (i.e., has the same nucleotide sequence and targets the same region on a target mRNA). In certain embodiments, at least one antisense compound of the polynucleotide nanostructure is different from at least one other antisense compound of the polynucleotide nanostructure. In certain embodiments, each antisense compound of each individual polynucleotide strand is different (e.g., has a different nucleotide sequence and / or targets different mRNA). In certain embodiments, the polynucleotide nanostructure comprises Formula II: wherein: corresponds to a first antisense compound; corresponds to a second antisense compound; and corresponds to a third antisense compound. In certain embodiments, the individual polynucleotide strand of n = 1 comprises (N)x(N)yUCGCUUCUAGGAGAU(N)zCUUUCAACUUCACAC, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, wherein y corresponds to an integer of between 1 to 10, wherein z corresponds to an integer of between 4 to 25. In certain embodiments, the individual polynucleotide strand of n = 2 comprises (N)x(N)yGUGUGAAGUUGAAAG(N)zGUGAUGUCAUCAAUG, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, wherein y corresponds to an integer of between 1 to 10, wherein z corresponds to an integer of between 4 to 25. In certain embodiments, the individual polynucleotide strand of n = 3 comprises (N)x(N)yCAUUGAUGACAUCAC(N)zAUCUCCUAGAAGCGA, wherein each N individually corresponds to any one of the nucleotides, wherein x corresponds to an integer of between 4 to 25, wherein y corresponds to an integer of between 1 to 10, wherein z corresponds to an integer of between 4 to 25. In certain embodiments, x corresponds to an integer of 15, wherein y corresponds to an integer of 2, and wherein z corresponds to an integer of 12. In certain embodiments, the individual polynucleotide strand of n = 1 comprises (N)x(N)yUCGCUUCUAGGAGAUUUAUUGACACUUCUUUCAACUUCACAC, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, and wherein y corresponds to an integer of between 1 to 10. In certain embodiments, the individual polynucleotide strand of n = 2 comprises (N)x(N)yGUGUGAAGUUGAAAGUUAUUGACACUUGUGAUGUCAUCAAUG, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, and wherein y corresponds to an integer of between 1 to 10. In certain embodiments, the individual polynucleotide strand of n = 3 comprises (N)x(N)yCAUUGAUGACAUCACUUAUUGACACUUAUCUCCUAGAAGCGA, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, and wherein y corresponds to an integer of between 1 to 10. In certain embodiments, the polynucleotide nanostructure comprises Formula III:

[0002] wherein: corresponds to a first antisense compound; corresponds to a second antisense compound; corresponds to a third antisense compound; and corresponds to a fourth antisense compound. In certain embodiments, the individual polynucleotide strand of n = 1 comprises (N)x(N)yUCGCUUCUAGGAGAU(N)zCUUUCAACUUCACAC, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, wherein y corresponds to an integer of between 1 to 10, wherein z corresponds to an integer of between 4 to 25. In certain embodiments, the individual polynucleotide strand of n = 2 comprises (N)x(N)yGUGUGAAGUUGAAAG(N)zGUGAUGUCAUCAAUG, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, wherein y corresponds to an integer of between 1 to 10, wherein z corresponds to an integer of between 4 to 25. In certain embodiments, the individual polynucleotide strand of n = 3 comprises (N)x(N)yCAUUGAUGACAUCAC(N)zCAGCAAACCUUACUC, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, wherein y corresponds to an integer of between 1 to 10, wherein z corresponds to an integer of between 4 to 25. In certain embodiments, the individual polynucleotide strand of n = 4 comprises (N)x(N)yGAGUAAGGUUUGCUG(N)zAUCUCCUAGAAGCGA, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, wherein y corresponds to an integer of between 1 to 10, wherein z corresponds to an integer of between 4 to 25. In certain embodiments, x corresponds to an integer of 15, wherein y corresponds to an integer of 2, and wherein z corresponds to an integer of 12. In certain embodiments, the individual polynucleotide strand of n = 1 comprises (N)x(N)yUCGCUUCUAGGAGAUUUAUUGACACUUCUUUCAACUUCACAC, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, and wherein y corresponds to an integer of between 1 to 10. In certain embodiments, the individual polynucleotide strand of n = 2 comprises (N)x(N)yGUGUGAAGUUGAAAGUUAUUGACACUUGUGAUGUCAUCAAUG, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, and wherein y corresponds to an integer of between 1 to 10. In certain embodiments, the individual polynucleotide strand of n = 3 comprises (N)x(N)yCAUUGAUGACAUCACUUAUUGACACUUCAGCAAACCUUACUC, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, and wherein y corresponds to an integer of between 1 to 10. In certain embodiments, the individual polynucleotide strand of n = 4 comprises (N)x(N)yGAGUAAGGUUUGCUGUUAUUGACACUUAUCUCCUAGAAGCGA, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, and wherein y corresponds to an integer of between 1 to 10. In certain embodiments, at least one polynucleotide scaffold portion of the individual polynucleotide strand comprises an additional antisense compound hybridized to the polynucleotide scaffold portion. In certain embodiments, each polynucleotide scaffold portion of each individual polynucleotide strand comprises an additional antisense compound hybridized to the polynucleotide scaffold portion. In another aspect, the disclosure provides a polynucleotide nanostructure comprising X total polynucleotide strands of Formula IV: wherein: X corresponds to an integer of at least 3 (e.g., 3-15); n corresponds to an individual polynucleotide strand of the polynucleotide nanostructure of X total polynucleotide strands; corresponds to an antisense compound; corresponds to a region of complementarity to the antisense compound in the individual polynucleotide strand; corresponds to a region of complementarity to individual polynucleotide strand of n-1 in the individual polynucleotide strand of n; corresponds to a region of complementarity to individual polynucleotide strand of n+1 in in the individual polynucleotide strand of n; wherein individual polynucleotide strand of n = 1 (i.e., the first polynucleotide strand) and individual polynucleotide strand of n = X (i.e., the last polynucleotide strand) each comprise a region of complementarity to each other; corresponds to Linker 1, optionally wherein Linker 1 is absent; and corresponds to Linker 2, optionally wherein Linker 2 is absent. In certain embodiments, X is 3-15. In certain embodiments, X is 3. In certain embodiments, X is 4. In certain embodiments, X is 5. In certain embodiments, X is 6. In certain embodiments, X is 7. In certain embodiments, X is 8. In certain embodiments, X is 9. In certain embodiments, X is 10. In certain embodiments, X is 11. In certain embodiments, X is 12. In certain embodiments, X is 13. In certain embodiments, X is 14. In certain embodiments, X is 15. In certain embodiments, the polynucleotide nanostructure comprises Formula V: wherein: corresponds to a first antisense compound; corresponds to a second antisense compound; and corresponds to a third antisense compound. In one aspect, the disclosure provides a polynucleotide nanostructure comprising Formula VI:

[0003] wherein: corresponds to a first antisense compound; corresponds to a second antisense compound; corresponds to a third antisense compound; corresponds to a region of complementarity to the antisense compound (e.g., a sense strand); corresponds to a region of complementarity to corresponds to a region of complementarity to corresponds to Linker 1, optionally wherein Linker 1 is absent; and corresponds to Linker 2, optionally wherein Linker 2 is absent. In one aspect, the disclosure provides a polynucleotide nanostructure comprising Formula VII:

[0004] wherein: corresponds to a first antisense compound; corresponds to a second antisense compound; corresponds to a third antisense compound; corresponds to a fourth antisense compound; comprises a region of complementarity to the fourth antisense compound (e.g., a sense strand), a region of complementarity to and a region of complementarity to ; comprises a region of complementarity to the first antisense compound (e.g., a sense strand), a region of complementarity to and a region of complementarity o comprises a region of complementarity to the second antisense compound (e.g., a sense strand), a region of complementarity to and a region of complementarity to comprises a region of complementarity to the third antisense compound (e.g., a sense strand), a region of complementarity to and a region of complementarity o and corresponds to a linker, optionally wherein the linker is absent. In one aspect, the disclosure provides a method of silencing one or more different target mRNA in a cell of a subject, the method comprising administering to the subject the polynucleotide nanostructure describe. In certain embodiments, the polynucleotide nanostructure is administered the central nervous system of the subject and the cell is a cell of the central nervous system. In certain embodiments, the polynucleotide nanostructure is administered via intracerebroventricular (ICV) injection or intrastriatal (IS) injection. In certain embodiments, the polynucleotide nanostructure is administered systemically to the subject and the cell is a kidney cell. In certain embodiments, the polynucleotide nanostructure is administered systemically to the subject and the cell is a heart cell. In certain embodiments, the polynucleotide nanostructure is administered systemically to the subject and the cell is a muscle cell. In certain embodiments, the polynucleotide nanostructure is administered systemically to the subject and the cell is a skin cell. In certain embodiments, the polynucleotide nanostructure is administered systemically to the subject and the cell is a adipose cell. In certain embodiments, the polynucleotide nanostructure is administered via intravenous (IV) injection or subcutaneous (SQ) injection. In certain embodiments, the polynucleotide nanostructure is administered to a lung of subject and the cell is a lung cell. In another aspect, the disclosure provides a method of treating or managing a neurodegenerative disease comprising administering to a subject in need of such treatment a therapeutically effective amount of said polynucleotide nanostructure described herein, thereby treating or managing the neurodegenerative disease. In another aspect, the disclosure provides a method of treating or managing a kidney disease comprising administering to a subject in need of such treatment a therapeutically effective amount of said polynucleotide nanostructure described herein, thereby treating or managing the kidney disease. In another aspect, the disclosure provides a method of treating or managing a lung disease comprising administering to a subject in need of such treatment a therapeutically effective amount of said polynucleotide nanostructure described herein, thereby treating or managing the lung disease. In another aspect, the disclosure provides a method of treating or managing a heart disease comprising administering to a subject in need of such treatment a therapeutically effective amount of said polynucleotide nanostructure described herein, thereby treating or managing the heart disease. In another aspect, the disclosure provides a method of treating or managing a muscle disease comprising administering to a subject in need of such treatment a therapeutically effective amount of said polynucleotide nanostructure described herein, thereby treating or managing the muscle disease. In another aspect, the disclosure provides a method of treating or managing a skin disease comprising administering to a subject in need of such treatment a therapeutically effective amount of said polynucleotide nanostructure described herein, thereby treating or managing the skin disease. In another aspect, the disclosure provides a method of treating or managing a disease of adipose tissue comprising administering to a subject in need of such treatment a therapeutically effective amount of said polynucleotide nanostructure described herein, thereby treating or managing the disease of adipose tissue. BRIEF DESCRIPTION OF THE DRAWINGS FIG.1 depicts schematics of four RNA nanostructures. The term “AS” corresponds to an antisense strand. The term “S” corresponds to a sense strand. Circles correspond to cleavable corners composed of deoxyribonucleotides with phosphodiester internucleotide linkages. FIG. 2 depicts a dose response curve of relative HTT mRNA expression in cells incubated with one of four RNA triangle nanostructures. FIG.3 depicts a dose response curve of relative HTT (triangle target 3), MSH3 (triangle target 1), and JAK1 (triangle target 2) mRNA expression in cells incubated with a multi- targeting RNA triangle nanostructure. FIG.4A – FIG.4B depict relative HTT expression in various mouse brain tissues 2- weeks post injection (FIG.4A) and two-months post injection (FIG.4B) of the RNA triangle nanostructures or controls. FIG.5A – FIG.5B depict relative HTT, MSH3, and JAK1 expression in various mouse brain tissues 2-weeks post injection (FIG.5A) and two-months post injection (FIG.5B) of the RNA triangle nanostructures or controls. FIG. 6 depicts relative HTT silencing in various brain tissues after 1 month of treatment. FIG. 7A – FIG. 7B depict relative HTT, MSH3, JAK1, and MECP2 expression in various mouse brain tissues 1 month post injection. FIG.8 depicts PK measurements as determined by compound concentration in serum of mice over time. FIG.9A – FIG.9B depict silencing (FIG.9A) and tissue accumulation (FIG.9B) of the triangle and square nanostructures following intravenous injection. FIG.10A – FIG.10B depict silencing (FIG.10A) and tissue accumulation (FIG.10B) of the triangle and square nanostructures following subcutaneous injection. FIG.11A – FIG.11B depict silencing in liver (FIG.11A) and heart (FIG.11B) of the square nanostructure targeting HTT, JAK1, MECP2, and MSH3. FIG. 12 depicts HTT silencing in several brain tissues from a fully modified RNA triangle nanostructure (Tv43xHtt) and an RNA triangle nanostructure with DNA nucleotides in the scaffold region (Tv43xHtt mod v3). FIG. 13A – FIG. 13B depict schematics of antisense strand single stranded nucleotide overhang orientations. FIG.13A provides a schematic where the 3’ single stranded nucleotide overhang extends away from the polynucleotide nanostructure and FIG. 13B provides a schematic where the 3’ single stranded nucleotide overhang extends towards the polynucleotide nanostructure. FIG.14A depicts schematics of three different triangle polynucleotide nanostructures tested for HTT silencing. Tv4+ 1xDCA contains a DCA lipid conjugate. FIG.14B depicts relative HTT silencing of the three different triangle polynucleotide nanostructures shown in FIG.14A. FIG. 15 depicts relative HTT silencing of triangle polynucleotide nanostructures having 1, 2, or 3 DCA lipid conjugates. The tested structures were Tv43xHTT, Tv43xHTT 1Xdca, Tv4 3xHTT 2xDCA, Tv4 3xHTT 3xDCA, a monovalent siRNA targeting HTT conjugated with DCA, a monovalent siRNA targeting a non-target control conjugated with DCA, and an Arm tv4 1xDCA. Mice were subcutaneously injected with 30 nmol of the compounds and organs were harvested 2 weeks later. HTT expression was measured in heart, lung, muscle, and liver. FIG. 16 depicts relative HTT silencing of triangle polynucleotide nanostructures having varied molecular weights. The nanostructure of Tv4 (A) is about 73 kDa. The nanostructure of Tv4 size 2 (B) is about 63 kDa. The nanostructure of Tv4 size 3 (C) is about 55 kDa. Mice were injected intravenously with 20 nmol of the compounds and organs were harvested 2 weeks later. HTT expression was measured in heart, lung, muscle, liver, kidney, and spleen. FIG. 17 depicts relative silencing of HTT, JAK1, MECP2, and MSH3 from a square polynucleotide nanostructure with antisense compounds targeting HTT, JAK1, MECP2, and MSH3. The square polynucleotide nanostructure was compared against a combination of a monovalent siRNA targeting HTT with a DCA conjugate and a monovalent siRNA targeting JAK1 with a DCA conjugate. Mice were injected subcutaneously with 40 nmol of the compounds and organs were harvested 2 weeks later. HTT, JAK1, MECP2, and MSH3 expression was measured in heart, muscle, and fat. FIG. 18A – FIG. 18C depict relative silencing of HTT from triangle polynucleotide nanostructures with antisense compounds targeting HTT. Mice were injected via bilateral ICV administration with 10 nmol of the compounds and brain structures were harvested 2 weeks later (FIG.18A), 2 months later (FIG.18B), and 6 months later (FIG.18C). HTT expression was measured in frontal cortex, striatum, thalamus, hippocampus, medial cortex, posterior cortex, cerebellum, and brain stem. The data for each brain structure, from left to right, are NTC siRNA, HTT monovalent siRNA, HTT divalent siRNA, an arm siRNA structure, a Tv4 structure with three antisense compounds targeting HTT, and a Tv4 structure with three antisense compounds with only one targeting HTT. DETAILED DESCRIPTION The polynucleotide nanostructures (e.g., RNA nanostructures) described herein provide an effective, inexpensive, and reproducible means for delivering multiple antisense compounds (e.g., siRNA or ASOs) to cells and tissue of a subject. In certain embodiments, each individual polynucleotide strand that makes up the polynucleotide nanostructure is 120 nucleotides or less (e.g., 40-120 nucleotides, 40-100 nucleotides, 40-80 nucleotides, 40-60 nucleotides, 60-120 nucleotides, 60-100 nucleotides, or 60-80 nucleotides). The short length of each strand facilities inexpensive chemical synthesis of each strand with high yield and minimal strand fragments. The polynucleotide nanostructures (e.g., RNA nanostructures) described herein allow for multi-mRNA targeting, being capable of targeting at least 3 different mRNA in a single cell in a subject administered the polynucleotide nanostructure. Since each antisense compound is hybridized to the polynucleotide nanostructure (at least 3 antisense compounds) all antisense compounds on a single polynucleotide nanostructure are delivered in each cell that takes up the polynucleotide nanostructure after administration to the subject. This advantageously ensures homogeneous modulation (e.g., silencing) of expression from each different target mRNA from each antisense compound. Thus, through multi-mRNA targeting, entire disease pathways may be silenced for potentially greater therapeutic effect. The size (e.g., molecular weight) of the polynucleotide nanostructures (e.g., RNA nanostructures) described herein can be modified by increasing the number of individual polynucleotide strands. With polynucleotide nanostructures of at least three individual polynucleotide strands (with a molecular weight typically over 50 kDa), the rate of kidney clearance is decreased (relative to isolated antisense compounds not hybridized to a polynucleotide nanostructure). Thus, the pharmacokinetics of blood clearance of the polynucleotide nanostructures can be modulated without the requirement of a conjugated functional moiety (although functional moieties may be conjugated to any one of the individual polynucleotide strands to further enhance one or more properties of the polynucleotide nanostructure). The polynucleotide nanostructures (e.g., RNA nanostructures) described herein may comprise one or more chemically modified nucleotides. In certain embodiments, all nucleotides in the polynucleotide nanostructure are chemically modified (e.g., all ribose 2’OH groups are chemically modified). This high level of modification greatly enhances the stability of the polynucleotide nanostructures, allowing for increased and prolonged modulation (e.g., silencing) of the target mRNA. Polynucleotide Nanostructures As used herein, the term “polynucleotide nanostructure” refers to a compound composed of at least three separate polynucleotide strands, where each strand has two regions of complementarity, each region comprising complementarity to a different polynucleotide strand. Exemplary, non-limiting arrangements of polynucleotide nanostructures are described below: 1) Polynucleotide nanostructure consisting of three individual polynucleotide strands, wherein individual polynucleotide strand #1 comprises a region of complementarity to individual polynucleotide strand #2 and individual polynucleotide strand #3, individual polynucleotide strand #2 comprises a region of complementarity to individual polynucleotide strand #1 and individual polynucleotide strand #3, and individual polynucleotide strand #3 comprises a region of complementarity to individual polynucleotide strand #1 and individual polynucleotide strand #2. 2) Polynucleotide nanostructure consisting of four individual polynucleotide strands, wherein individual polynucleotide strand #1 comprises a region of complementarity to individual polynucleotide strand #2 and individual polynucleotide strand #4, individual polynucleotide strand #2 comprises a region of complementarity to individual polynucleotide strand #1 and individual polynucleotide strand #3, individual polynucleotide strand #3 comprises a region of complementarity to individual polynucleotide strand #2 and individual polynucleotide strand #4, and individual polynucleotide strand #4 comprises a region of complementarity to individual polynucleotide strand #1 and individual polynucleotide strand #3. 3) Polynucleotide nanostructure consisting of five individual polynucleotide strands, wherein individual polynucleotide strand #1 comprises a region of complementarity to individual polynucleotide strand #2 and individual polynucleotide strand #5, individual polynucleotide strand #2 comprises a region of complementarity to individual polynucleotide strand #1 and individual polynucleotide strand #3, individual polynucleotide strand #3 comprises a region of complementarity to individual polynucleotide strand #2 and individual polynucleotide strand #4, individual polynucleotide strand #4 comprises a region of complementarity to individual polynucleotide strand #3 and individual polynucleotide strand #5, and individual polynucleotide strand #5 comprises a region of complementarity to individual polynucleotide strand #1 and individual polynucleotide strand #4. 4) Polynucleotide nanostructure consisting of six individual polynucleotide strands, wherein individual polynucleotide strand #1 comprises a region of complementarity to individual polynucleotide strand #2 and individual polynucleotide strand #6, individual polynucleotide strand #2 comprises a region of complementarity to individual polynucleotide strand #1 and individual polynucleotide strand #3, individual polynucleotide strand #3 comprises a region of complementarity to individual polynucleotide strand #2 and individual polynucleotide strand #4, individual polynucleotide strand #4 comprises a region of complementarity to individual polynucleotide strand #3 and individual polynucleotide strand #5, individual polynucleotide strand #5 comprises a region of complementarity to individual polynucleotide strand #4 and individual polynucleotide strand #6, and individual polynucleotide strand #6 comprises a region of complementarity to individual polynucleotide strand #1 and individual polynucleotide strand #5. As used herein, a “region of complementary” of an individual polynucleotide strand refers to a portion of the individual polynucleotide strand that has sufficient base pair complementary to another individual polynucleotide strand to hybridize to said individual polynucleotide strand. Sufficient base pair complementary need not be complete, with mismatches permissible. For example, a sufficient base pair complementary to hybridize may be a base pair complementary that maintains hybridization in serum at 37 °C for 30 minutes or more. In one aspect, the disclosure provides a polynucleotide nanostructure comprising X total polynucleotide strands of Formula I: wherein: X corresponds to an integer of at least 3 (e.g., 3-15); n corresponds to an individual polynucleotide strand of the polynucleotide nanostructure of X total polynucleotide strands; corresponds to an antisense compound; corresponds to a region of complementarity to the antisense compound in the individual polynucleotide strand; corresponds to a region of complementarity to individual polynucleotide strand of n-1 in the individual polynucleotide strand of n; corresponds to a polynucleotide scaffold portion of the individual polynucleotide strand; and corresponds to a region of complementarity to individual polynucleotide strand of n+1 in in the individual polynucleotide strand of n; wherein individual polynucleotide strand of n = 1 (i.e., the first polynucleotide strand) and individual polynucleotide strand of n = X (i.e., the last polynucleotide strand) each comprise a region of complementarity to each other; corresponds to Linker 1, optionally wherein Linker 1 is absent; and corresponds to Linker 2, optionally wherein Linker 2 is absent. In certain embodiments, X is 3-15. In certain embodiments, X is 3. In certain embodiments, X is 4. In certain embodiments, X is 5. In certain embodiments, X is 6. In certain embodiments, X is 7. In certain embodiments, X is 8. In certain embodiments, X is 9. In certain embodiments, X is 10. In certain embodiments, X is 11. In certain embodiments, X is 12. In certain embodiments, X is 13. In certain embodiments, X is 14. In certain embodiments, X is 15. In certain embodiments, each individual polynucleotide strand is between 20 nucleotides and 120 nucleotides in length. In certain embodiments, each individual polynucleotide strand is between 40-120 nucleotides, 40-100 nucleotides, 40-80 nucleotides, 40-60 nucleotides, 60-120 nucleotides, 60- 100 nucleotides, or 60-80 nucleotides. In certain embodiments, the region of complementarity to the antisense compound in the individual polynucleotide strand (i.e., ) is between 4 nucleotides to 40 nucleotides in length. In certain embodiments, the region of complementarity to the antisense compound in the individual polynucleotide strand (i.e., ) is 4 nucleotides in length, 5 nucleotides in length, 6 nucleotides in length, 7 nucleotides in length, 8 nucleotides in length, 9 nucleotides in length, 10 nucleotides in length, 11 nucleotides in length, 12 nucleotides in length, 13 nucleotides in length, 14 nucleotides in length, 15 nucleotides in length, 16 nucleotides in length, 17 nucleotides in length, 18 nucleotides in length, 19 nucleotides in length, 20 nucleotides in length, 21 nucleotides in length, 22 nucleotides in length, 23 nucleotides in length, 24 nucleotides in length, or 25 nucleotides in length. In certain embodiments, the region of complementarity between individual polynucleotide strands is between 4 nucleotides to 40 nucleotides in length. In certain embodiments, the region of complementarity between individual polynucleotide strands is 4 nucleotides in length, 5 nucleotides in length, 6 nucleotides in length, 7 nucleotides in length, 8 nucleotides in length, 9 nucleotides in length, 10 nucleotides in length, 11 nucleotides in length, 12 nucleotides in length, 13 nucleotides in length, 14 nucleotides in length, 15 nucleotides in length, 16 nucleotides in length, 17 nucleotides in length, 18 nucleotides in length, 19 nucleotides in length, 20 nucleotides in length, 21 nucleotides in length, 22 nucleotides in length, 23 nucleotides in length, 24 nucleotides in length, or 25 nucleotides in length. In certain embodiments, the region of complementarity between in an individual polynucleotide strand (e.g., n = 1) and in an adjacent individual polynucleotide strand (n = 2) is between 4 nucleotides to 40 nucleotides in length. In certain embodiments, the polynucleotide scaffold portion of the individual polynucleotide strand is between 4 nucleotides to 40 nucleotides in length. In certain embodiments, the polynucleotide scaffold portion of the individual polynucleotide strand is 4 nucleotides in length, 5 nucleotides in length, 6 nucleotides in length, 7 nucleotides in length, 8 nucleotides in length, 9 nucleotides in length, 10 nucleotides in length, 11 nucleotides in length, 12 nucleotides in length, 13 nucleotides in length, 14 nucleotides in length, 15 nucleotides in length, 16 nucleotides in length, 17 nucleotides in length, 18 nucleotides in length, 19 nucleotides in length, 20 nucleotides in length, 21 nucleotides in length, 22 nucleotides in length, 23 nucleotides in length, 24 nucleotides in length, 25 nucleotides in length, 26 nucleotides in length, 27 nucleotides in length, 28 nucleotides in length, 29 nucleotides in length, or 30 nucleotides in length. In certain embodiments, i) the region of complementarity to the antisense compound, ii) the region of complementarity between individual polynucleotide strands, and iii) the polynucleotide scaffold portion of the individual polynucleotide strand, are identical nucleotides in length. In certain embodiments, each antisense compound of each individual polynucleotide strand is identical (i.e., has the same nucleotide sequence and targets the same region on a target mRNA). In certain embodiments, at least one antisense compound of the polynucleotide nanostructure is different from at least one other antisense compound of the polynucleotide nanostructure. In certain embodiments, each antisense compound of each individual polynucleotide strand is different (e.g., has a different nucleotide sequence and / or targets different mRNA). In certain embodiments, the polynucleotide nanostructure comprises Formula II:

[0005] wherein: corresponds to a first antisense compound; corresponds to a second antisense compound; and corresponds to a third antisense compound. In certain embodiments, the individual polynucleotide strand of n = 1 comprises (N)x(N)yUCGCUUCUAGGAGAU(N)zCUUUCAACUUCACAC, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, wherein y corresponds to an integer of between 1 to 10, wherein z corresponds to an integer of between 4 to 25. In certain embodiments, the individual polynucleotide strand of n = 2 comprises (N)x(N)yGUGUGAAGUUGAAAG(N)zGUGAUGUCAUCAAUG, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, wherein y corresponds to an integer of between 1 to 10, wherein z corresponds to an integer of between 4 to 25. In certain embodiments, the individual polynucleotide strand of n = 3 comprises (N)x(N)yCAUUGAUGACAUCAC(N)zAUCUCCUAGAAGCGA, wherein each N individually corresponds to any one of the nucleotides, wherein x corresponds to an integer of between 4 to 25, wherein y corresponds to an integer of between 1 to 10, wherein z corresponds to an integer of between 4 to 25. In certain embodiments, x corresponds to an integer of 15, wherein y corresponds to an integer of 2, and wherein z corresponds to an integer of 12. In certain embodiments, the individual polynucleotide strand of n = 1 comprises (N)x(N)yUCGCUUCUAGGAGAUUUAUUGACACUUCUUUCAACUUCACAC, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, and wherein y corresponds to an integer of between 1 to 10. In certain embodiments, the individual polynucleotide strand of n = 2 comprises (N)x(N)yGUGUGAAGUUGAAAGUUAUUGACACUUGUGAUGUCAUCAAUG, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, and wherein y corresponds to an integer of between 1 to 10. In certain embodiments, the individual polynucleotide strand of n = 3 comprises (N)x(N)yCAUUGAUGACAUCACUUAUUGACACUUAUCUCCUAGAAGCGA, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, and wherein y corresponds to an integer of between 1 to 10. In certain embodiments, the polynucleotide nanostructure comprises Formula III: wherein: corresponds to a first antisense compound; corresponds to a second antisense compound; corresponds to a third antisense compound; and corresponds to a fourth antisense compound. In certain embodiments, the individual polynucleotide strand of n = 1 comprises (N)x(N)yUCGCUUCUAGGAGAU(N)zCUUUCAACUUCACAC, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, wherein y corresponds to an integer of between 1 to 10, wherein z corresponds to an integer of between 4 to 25. In certain embodiments, the individual polynucleotide strand of n = 2 comprises (N)x(N)yGUGUGAAGUUGAAAG(N)zGUGAUGUCAUCAAUG, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, wherein y corresponds to an integer of between 1 to 10, wherein z corresponds to an integer of between 4 to 25. In certain embodiments, the individual polynucleotide strand of n = 3 comprises (N)x(N)yCAUUGAUGACAUCAC(N)zCAGCAAACCUUACUC, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, wherein y corresponds to an integer of between 1 to 10, wherein z corresponds to an integer of between 4 to 25. In certain embodiments, the individual polynucleotide strand of n = 4 comprises (N)x(N)yGAGUAAGGUUUGCUG(N)zAUCUCCUAGAAGCGA, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, wherein y corresponds to an integer of between 1 to 10, wherein z corresponds to an integer of between 4 to 25. In certain embodiments, x corresponds to an integer of 15, wherein y corresponds to an integer of 2, and wherein z corresponds to an integer of 12. In certain embodiments, the individual polynucleotide strand of n = 1 comprises (N)x(N)yUCGCUUCUAGGAGAUUUAUUGACACUUCUUUCAACUUCACAC, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, and wherein y corresponds to an integer of between 1 to 10. In certain embodiments, the individual polynucleotide strand of n = 2 comprises (N)x(N)yGUGUGAAGUUGAAAGUUAUUGACACUUGUGAUGUCAUCAAUG, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, and wherein y corresponds to an integer of between 1 to 10. In certain embodiments, the individual polynucleotide strand of n = 3 comprises (N)x(N)yCAUUGAUGACAUCACUUAUUGACACUUCAGCAAACCUUACUC, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, and wherein y corresponds to an integer of between 1 to 10. In certain embodiments, the individual polynucleotide strand of n = 4 comprises (N)x(N)yGAGUAAGGUUUGCUGUUAUUGACACUUAUCUCCUAGAAGCGA, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, and wherein y corresponds to an integer of between 1 to 10. In certain embodiments, at least one polynucleotide scaffold portion of the individual polynucleotide strand comprises an additional antisense compound hybridized to the polynucleotide scaffold portion. In certain embodiments, each polynucleotide scaffold portion of each individual polynucleotide strand comprises an additional antisense compound hybridized to the polynucleotide scaffold portion. In another aspect, the disclosure provides a polynucleotide nanostructure comprising X total polynucleotide strands of Formula IV:

[0006] wherein: X corresponds to an integer of at least 3 (e.g., 3-15); n corresponds to an individual polynucleotide strand of the polynucleotide nanostructure of X total polynucleotide strands; corresponds to an antisense compound; corresponds to a region of complementarity to the antisense compound in the individual polynucleotide strand; corresponds to a region of complementarity to individual polynucleotide strand of n-1 in the individual polynucleotide strand of n; corresponds to a region of complementarity to individual polynucleotide strand of n+1 in in the individual polynucleotide strand of n; wherein individual polynucleotide strand of n = 1 (i.e., the first polynucleotide strand) and individual polynucleotide strand of n = X (i.e., the last polynucleotide strand) each comprise a region of complementarity to each other; corresponds to Linker 1, optionally wherein Linker 1 is absent; and corresponds to Linker 2, optionally wherein Linker 2 is absent. In certain embodiments, X is 3-15. In certain embodiments, X is 3. In certain embodiments, X is 4. In certain embodiments, X is 5. In certain embodiments, X is 6. In certain embodiments, X is 7. In certain embodiments, X is 8. In certain embodiments, X is 9. In certain embodiments, X is 10. In certain embodiments, X is 11. In certain embodiments, X is 12. In certain embodiments, X is 13. In certain embodiments, X is 14. In certain embodiments, X is 15. In certain embodiments, the polynucleotide nanostructure comprises Formula V: wherein: corresponds to a first antisense compound; corresponds to a second antisense compound; and corresponds to a third antisense compound. Linkers The polynucleotide nanostructures of the disclosure may contain one or more linkers connecting regions of the individual polynucleotide strands. Where a linker is a non-nucleotide linker, each region of an individual polynucleotide strand will still be considered an single individual polynucleotide strand and not multiple individual polynucleotide strands with intervening linkers. In certain embodiments, the linker (e.g., the Linker 1 and / or the Linker 2) comprises an ethylene glycol chain, an alkyl chain, a peptide, an RNA, a DNA, a phosphodiester, a phosphorothioate, a phosphoramidate, an amide, a carbamate, or a combination thereof. In certain embodiments, the linker (e.g., the Linker 1 and / or the Linker 2) comprises a cleavable linker. Cleavable linkers may be used to link the region of complementarity to the antisense compound to the rest of the individual polynucleotide strand. Thus, the antisense compound may be readily released from the polynucleotide structure as the appropriate time, such is in a cell of a subject. In certain embodiments, the cleavable linker comprises a phosphodiester linkage, a disulfide linkage, an acid-labile linkage, or a photocleavable linkage. In certain embodiments, the cleavable linker comprises a dNdN dinucleotide with phosphodiester internucleotide linkages, wherein each dN individually corresponds to a deoxyribonucleotide of A, T, G, or C. In certain embodiments, the acid-labile linkage comprises a β-thiopropionate linkage or a carboxydimethylmaleic anhydride (CDM) linkage. RNA Nanostructures The polynucleotide nanostructures described herein may be composed entirely or partially of RNA nucleotides, including chemically modified RNA nucleotides. In certain embodiments, the polynucleotide nanostructure is an RNA nanostructure. In certain embodiments, the RNA nanostructure comprises at least one modified nucleotide. In certain embodiments, the at least one modified nucleotide comprises a modification of a ribose group, a nucleobase, or a combination thereof. In certain embodiments, the modification of the ribose group is independently selected from the group consisting of 2'-O-methyl, 2’-fluoro, 2’-O-(2-methoxyethyl) (MOE), 2’-NH2 (2’-amino), a bicyclic nucleotide, a locked nucleic acid (LNA), a 2’-(S)-constrained ethyl (S-cEt), a constrained MOE, and a 2'-O,4'-C-aminomethylene bridged nucleic acid (2',4'-BNANC). In certain embodiments, the RNA nanostructure comprises a 2'-O-methyl modification and a 2’-fluoro modification. In certain embodiments, at least 80% of the ribose groups are chemically modified. In certain embodiments, at least 90% of the ribose groups are chemically modified. In certain embodiments, 100% of the ribose groups are chemically modified. In certain embodiments, 100% of the ribose groups are chemically modified with a combination of a 2'-O-methyl modification and a 2’-fluoro modification. In certain embodiments, the modification of the nucleobase is independently selected from the group consisting of 2-thiouridine, 4-thiouridine, N6-methyladenosine, pseudouridine, 2,6-diaminopurine, inosine, thymidine, 5-methylcytosine, 5-substituted pyrimidine, isoguanine, isocytosine, or halogenated aromatic groups. In certain embodiments, the RNA nanostructure comprises at least one modified internucleotide linkage. In certain embodiments, the at least one modified internucleotide linkage comprises a phosphorothioate internucleotide linkage. In certain embodiments, each individual polynucleotide strand comprises 1-6 phosphorothioate internucleotide linkages at the 5’ end and / or 3’ end of the individual polynucleotide strand. Antisense Compound As used herein, the term “antisense compound” refers to an oligonucleotide that is capable of hybridizing to the polynucleotide nanostructures described herein and comprises sufficient complementarity to a target mRNA to modulate the expression of said mRNA. The antisense compounds described herein hybridize to a region of complementarity on each individual polynucleotide strand. In certain embodiments, every individual polynucleotide strand of a polynucleotide nanostructure has a hybridized antisense compound. In certain embodiments, the region of complementarity to the antisense compound in the individual polynucleotide strand is between 4 nucleotides to 40 nucleotides in length. In certain embodiments, the region of complementarity to the antisense compound in the individual polynucleotide strand is 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 21, 24, 26, 28, 30, 32, 34, 36, 38 or 40 nucleotides in length. Antisense Compound – siRNA In certain embodiments, the antisense compound is an antisense strand of a small interfering RNA (siRNA). SiRNAs are typically composed of two strands, the antisense strand which is substantially complementary to a section of about 10-50 nucleotides, e.g., about 15- 30, 16-25, 18-23 or 19-22 nucleotides of a target mRNA for silencing, and the sense strand, which has sufficient complementarity to the antisense strand to form a duplex, each strand having a 5’ end and a 3’ end. The antisense strand comprises a region of complementary to an individual polynucleotide strand of the polynucleotide nanostructure. The portion of the individual polynucleotide strand that binds to the antisense strand serves as the sense strand of the siRNA (i.e., the sense strand portion of the individual polynucleotide strand, also described as a region of complementarity to the antisense compound in the individual polynucleotide strand or ). In certain embodiments, a linker as described herein (e.g., a Linker 1 or Linker 2) is present between the sense strand portion of the individual polynucleotide strand and the remaining portion of the individual polynucleotide strand. In some embodiments, the linker is cleavable. Accordingly, in some embodiments, the antisense strand and sense strand portion are released from the polynucleotide nanostructure when administered to a subject, such as when said polynucleotide nanostructure is taken up by a cell in the subject. In certain embodiments, the antisense strand comprises between 15 nucleotides to 25 nucleotides in length. In certain embodiments, the antisense strand is 18 nucleotides in length. In certain embodiments, the antisense strand is 19 nucleotides in length. In certain embodiments, the antisense strand is 20 nucleotides in length. In certain embodiments, the antisense strand is 21 nucleotides in length. In certain embodiments, the antisense strand is 22 nucleotides in length. In certain embodiments, the sense strand portion of the individual polynucleotide strand is 8 nucleotides in length. In certain embodiments, the sense strand portion of is 9 nucleotides in length. In certain embodiments, the sense strand portion of is 10 nucleotides in length. In certain embodiments, the sense strand portion of is 11 nucleotides in length. In certain embodiments, the sense strand portion of is 12 nucleotides in length. In certain embodiments, the sense strand portion of is 13 nucleotides in length. In certain embodiments, the sense strand portion of is 14 nucleotides in length. In certain embodiments, the sense strand portion of is 15 nucleotides in length. In certain embodiments, the sense strand portion is 16 nucleotides in length. In certain embodiments, the sense strand portion is 18 nucleotides in length. In certain embodiments, the sense strand portion is 20 nucleotides in length. In certain embodiments, the antisense strand comprises a single stranded nucleotide overhang. The single stranded nucleotide overhang lacks complementarity to the polynucleotide nanostructure. In certain embodiments, the antisense strand comprises a single stranded nucleotide overhang at the antisense strand 3’ end. The 3’ single stranded nucleotide overhang may extend away from the polynucleotide nanostructure or extend in towards the polynucleotide nanostructure. An example using the polynucleotide nanostructures of Formula I is provided in FIG.13A – FIG.13B. FIG.13A provides a schematic where the 3’ single stranded nucleotide overhang extends away from the polynucleotide nanostructure and FIG. 13B provides a schematic where the 3’ single stranded nucleotide overhang extends towards the polynucleotide nanostructure. In certain embodiments, the antisense strand comprises a 2-nucleotide to 5-nucleotide single stranded nucleotide overhang. In certain embodiments, the single stranded nucleotide overhang lacks complementarity to the polynucleotide nanostructure. In certain embodiments, the antisense strand forms a blunt end with the polynucleotide scaffold. The antisense strand comprises a sequence sufficiently complementary to a target sequence portion of the target mRNA to effect RISC-mediated cleavage of the target mRNA. Accordingly, in a certain embodiment, the antisense strand of the siRNA is designed to have a sequence sufficiently complementary to a portion of the target. For example, the antisense strand may have 100% complementarity to the target site. However, 100% complementarity is not required. Greater than 80% identity, e.g., 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or even 100% complementarity, between the antisense strand and the target RNA sequence is contemplated. The antisense strand of the disclosure is able to tolerate certain sequence variations to enhance efficiency and specificity of RNAi. In one embodiment, the antisense strand has 4, 3, 2, 1, or 0 mismatched nucleotide(s) with a target region, such as a target region that differs by at least one base pair between a wild-type and mutant allele, e.g., a target region comprising the gain- of-function mutation, and the other strand is identical or substantially identical to the first strand. Moreover, siRNA sequences with small insertions or deletions of 1 or 2 nucleotides may also be effective for mediating RNAi. Alternatively, siRNA sequences with nucleotide analog substitutions or insertions can be effective for inhibition. In certain embodiments, the antisense strand comprises a 5’ phosphate, a 5’-alkyl phosphonate, a 5’ alkylene phosphonate, or a 5’ alkenyl phosphonate. In certain embodiments, the antisense strand comprises a 5’ vinyl phosphonate. In certain embodiments, the antisense compound (e.g., antisense strand) comprises at least one modified nucleotide. In certain embodiments, the at least one modified nucleotide comprises a modification of a ribose group, a nucleobase, or a combination thereof. In certain embodiments, the modification of the ribose group is independently selected from the group consisting of 2'-O-methyl, 2’-fluoro, 2’-O-(2-methoxyethyl) (MOE), 2’-NH2 (2’-amino), a bicyclic nucleotide, a locked nucleic acid (LNA), a 2’-(S)-constrained ethyl (S- cEt), a constrained MOE, and a 2'-O,4'-C-aminomethylene bridged nucleic acid (2',4'- BNANC). In certain embodiments, at least 80% of the ribose groups are chemically modified. In certain embodiments, at least 90% of the ribose groups are chemically modified. In certain embodiments, 100% of the ribose groups are chemically modified. In certain embodiments, the modification of the nucleobase is independently selected from the group consisting of 2-thiouridine, 4-thiouridine, N6-methyladenosine, pseudouridine, 2,6-diaminopurine, inosine, thymidine, 5-methylcytosine, 5-substituted pyrimidine, isoguanine, isocytosine, or halogenated aromatic groups. In certain embodiments, the antisense compound (e.g., antisense strand) comprises at least one modified internucleotide linkage. In certain embodiments, the at least one modified internucleotide linkage comprises a phosphorothioate internucleotide linkage. Antisense Compound – Antisense Oligonucleotide (ASO) In certain embodiments, the antisense compound is an antisense oligonucleotide (ASO). As used herein, the term “antisense oligonucleotide” or “ASO” refers to an oligonucleotide molecule which is capable of binding to RNA inside cells by Watson-Crick base pairing. Depending on the sequence and chemistry of the antisense oligonucleotide, this interaction can lead to silencing of a target gene (i.e. reducing the level of expression of mature mRNA and / or protein from that gene) or activation of a target gene (i.e. increasing the level of expression of mature mRNA and / or protein from that gene). The antisense oligonucleotides of the present disclosure are focused on activating gene expression, which can be done utilizing different mechanisms. Some antisense oligonucleotides are designed to recruit RNase H to cleave their target RNAs. RNase H is a family of non-sequence-specific endonuclease enzymes that catalyze the cleavage of RNA in an RNA / DNA substrate via a hydrolytic mechanism. In certain embodiments, the antisense oligonucleotides of the disclosure trigger RNase H-mediated cleavage of a pre-mRNA target, which can be compatible with activation of overall target gene expression. Other antisense oligonucleotides, called steric blockers, are designed not to elicit cleavage of their targets but to block interactions with cellular factors. For example, these cellular factors could modulate splicing, block interactions of noncoding RNAs or of RNA- binding proteins, stabilize mRNA to prolong its half-life, or increase the efficiency of translation of an mRNA. In some embodiments, the steric blocking antisense oligonucleotides are splice switching oligonucleotides (SSOs), which modify alternative splicing of pre-mRNA. Antisense oligonucleotides designed to recruit RNase H are often designed as “gapmers.” The term “gapmer” means a chimeric antisense oligonucleotide in which an internal region having a plurality of nucleosides that support RNase H cleavage is positioned between external regions having one or more nucleosides, wherein the nucleosides comprising the internal region are chemically distinct from the nucleoside or nucleosides comprising the external regions. The internal region can be referred to as a “gap segment” and the external regions can be referred to as “wing segments.” “Chimeric antisense oligonucleotide” means an antisense oligonucleotide that has at least two chemically distinct regions. In some embodiments, the present disclosure provides an antisense oligonucleotide having a target-recognition sequence that is sufficiently complementary to a target transcript or portion thereof, to direct cleavage of the target transcript by RNase H. The target-recognition sequence of the antisense oligonucleotide can be the full length of the antisense oligonucleotide, or a portion thereof. In some embodiments, the antisense oligonucleotide comprises a gapmer motif. In the case of an ASO having a gapmer motif, the gap segment generally serves as the substrate for endonuclease cleavage, while the wing segments comprise modified nucleosides. In certain embodiments, the regions of a gapmer are differentiated by the types of sugar moieties comprising each distinct region. The types of sugar moieties that are used to differentiate the regions of a gapmer can in some embodiments include β-D-ribonucleosides, β-D-deoxyribonucleosides, 2′-modified nucleosides (such 2′-modified nucleosides can include 2′-MOE, and 2′-O-CH3 (i.e., OMe), among others), and bicyclic sugar modified nucleosides (such bicyclic sugar modified nucleosides can include those having a 4′-(CH2)n-O-2′ bridge, where n=1 or n=2). In some embodiments, the wing segments of the gapmer contain one or more tricyclo-DNA (tcDNA) modifications. In some embodiments, each distinct region comprises uniform sugar moieties. In some embodiments, each wing segment comprises a mixture of different nucleotide modifications. For example, in one embodiment, a LNA modification and a 2′-MOE modification could be used in combination for one ASO. In one embodiment, a LNA modification and a 2′-O-Methyl modification could be used in combination for one ASO. In one embodiment, a LNA modification and a 2′-deoxy modification could be used in combination for one ASO. In one embodiment, a LNA modification and a tricyclo-DNA modification could be used in combination for one ASO. In one embodiment, a 2′-MOE modification and a tricyclo-DNA modification could be used in combination for one ASO. In some embodiments, an ASO of the present disclosure directs cleavage of a target transcript by RNase H. In such embodiments, the ASO can be referred to as an RNase H- dependent ASO. In some embodiments the ASO is an RNase H-dependent antisense oligonucleotide. In some embodiments, an antisense oligonucleotide of the present disclosure is an RNase H-dependent antisense oligonucleotide, and can be a single-stranded, chemically modified oligonucleotide that binds to a complementary sequence in the target transcript (e.g., a target transcript). An RNase H-dependent antisense oligonucleotide of the present disclosure reduces expression of a target gene by RNase H-mediated cleavage of the target transcript, and by inhibition of translation by steric blockade of ribosomes. In some embodiments, an ASO of the present disclosure is capable of mediating cleavage of at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95% or more of target transcripts by RNase-H. In one embodiment, the ASO is capable of mediating cleavage of at least 80% of target transcripts by RNase-H. In one embodiment, the ASO is capable of mediating cleavage of at least 90% of target transcripts by RNase-H. In certain embodiments, an ASO that targets a target transcript is from about 6 to about 24 subunits in length. In other embodiments, the ASO that targets a target transcript is from about 8 to about 80 subunits in length. For example, the ASOs are 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, or 80 linked subunits in length, or a range defined by any two of the above values. In some embodiments, the ASOs are less than 40 linked subunits in length. In some embodiments, the ASOs are from about 10 to about 30 linked subunits in length. In some embodiments, the ASOs are from about 12 to about 25 linked subunits in length. In some embodiments, the ASOs are from about 15 to about 20 linked subunits in length. Antisense Compound – MicroRNA As used herein, the term “microRNA” (“miRNA”), also known in the art as “small temporal RNAs” (“stRNAs”), refers to a small (10-50 nucleotide) RNA, which are genetically encoded (e.g., by viral, mammalian, or plant genomes) and are capable of directing or mediating RNA silencing. Antisense Compound – Short hairpin RNA (shRNA) In contrast to siRNAs, shRNAs mimic the natural precursors of micro RNAs (miRNAs) and enter at the top of the gene silencing pathway. For this reason, shRNAs are believed to mediate gene silencing more efficiently by being fed through the entire natural gene silencing pathway. miRNAs are noncoding RNAs of approximately 22 nucleotides, which can regulate gene expression at the post transcriptional or translational level during plant and animal development. One common feature of miRNAs is that they are all excised from an approximately 70 nucleotide precursor RNA stem-loop termed pre-miRNA, probably by Dicer, an RNase III-type enzyme, or a homolog thereof. Naturally-occurring miRNA precursors (pre- miRNA) have a single strand that forms a duplex stem including two portions that are generally complementary, and a loop, that connects the two portions of the stem. In typical pre-miRNAs, the stem includes one or more bulges, e.g., extra nucleotides that create a single nucleotide "loop" in one portion of the stem, and / or one or more unpaired nucleotides that create a gap in the hybridization of the two portions of the stem to each other. Short hairpin RNAs, or engineered RNA precursors, of the present application are artificial constructs based on these naturally occurring pre-miRNAs, but which are engineered to deliver desired RNA silencing agents (e.g., siRNAs of the disclosure). By substituting the stem sequences of the pre-miRNA with sequence complementary to the target mRNA, a shRNA is formed. The shRNA is processed by the entire gene silencing pathway of the cell, thereby efficiently mediating RNAi. The requisite elements of a shRNA molecule include a first portion and a second portion, having sufficient complementarity to anneal or hybridize to form a duplex or double- stranded stem portion. The two portions need not be fully or perfectly complementary. The first and second "stem" portions are connected by a portion having a sequence that has insufficient sequence complementarity to anneal or hybridize to other portions of the shRNA. This latter portion is referred to as a "loop" portion in the shRNA molecule. The shRNA molecules are processed to generate siRNAs. shRNAs can also include one or more bulges, i.e., extra nucleotides that create a small nucleotide "loop" in a portion of the stem, for example a one-, two- or three-nucleotide loop. The stem portions can be the same length, or one portion can include an overhang of, for example, 1-5 nucleotides. The overhanging nucleotides can include, for example, uracils (Us), e.g., all Us. Such Us are notably encoded by thymidines (Ts) in the shRNA-encoding DNA which signal the termination of transcription. In shRNAs (or engineered precursor RNAs) of the instant disclosure, one portion of the duplex stem is a nucleic acid sequence that is complementary (or antisense) to the target mRNA sequence. In certain embodiments, one strand of the stem portion of the shRNA is sufficiently complementary (e.g., antisense) to a target RNA (e.g., mRNA) sequence to mediate degradation or cleavage of said target RNA via RNA interference (RNAi). Thus, engineered RNA precursors include a duplex stem with two portions and a loop connecting the two stem portions. The antisense portion can be on the 5' or 3' end of the stem. The stem portions of a shRNA are about 15 to about 50 nucleotides in length. In certain embodiments, the two stem portions are about 18 or 19 to about 21, 22, 23, 24, 25, 30, 35, 37, 38, 39, or 40 or more nucleotides in length. In certain embodiments, the length of the stem portions should be 21 nucleotides or greater. When used in mammalian cells, the length of the stem portions should be less than about 30 nucleotides to avoid provoking non-specific responses like the interferon pathway. In non-mammalian cells, the stem can be longer than 30 nucleotides. In fact, the stem can include much larger sections complementary to the target mRNA (up to, and including the entire mRNA). In fact, a stem portion can include much larger sections complementary to the target mRNA (up to, and including the entire mRNA). The two portions of the duplex stem must be sufficiently complementary to hybridize to form the duplex stem. Thus, the two portions can be, but need not be, fully or perfectly complementary. In addition, the two stem portions can be the same length, or one portion can include an overhang of 1, 2, 3, or 4 nucleotides. The overhanging nucleotides can include, for example, uracils (Us), e.g., all Us. The loop in the shRNAs or engineered RNA precursors may differ from natural pre-miRNA sequences by modifying the loop sequence to increase or decrease the number of paired nucleotides, or replacing all or part of the loop sequence with a tetraloop or other loop sequences. Thus, the loop in the shRNAs or engineered RNA precursors can be 2, 3, 4, 5, 6, 7, 8, 9, or more, e.g., 15 or 20, or more nucleotides in length. The loop in the shRNAs or engineered RNA precursors may differ from natural pre- miRNA sequences by modifying the loop sequence to increase or decrease the number of paired nucleotides, or replacing all or part of the loop sequence with a tetraloop or other loop sequences. Thus, the loop portion in the shRNA can be about 2 to about 20 nucleotides in length, i.e., about 2, 3, 4, 5, 6, 7, 8, 9, or more, e.g., 15 or 20, or more nucleotides in length. In certain embodiments, a loop consists of or comprises a "tetraloop" sequence. Exemplary tetraloop sequences include, but are not limited to, the sequences GNRA, where N is any nucleotide and R is a purine nucleotide, GGGG, and UUUU. Antisense Compound Target mRNA The polynucleotide nanostructures of the disclosure are capable of delivering at least three antisense compounds (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or more antisense compounds) to a single cell in a subject. The at least three antisense compounds may have identical nucleotide sequences, thereby targeting the same mRNA for enhanced target expression modulation (e.g., silencing) compared to a single antisense compound. Alternatively, one or more antisense compounds of the at least three antisense compounds may target a different mRNA (from a different gene) to modulate expression of more than one mRNA target in a cell. In certain embodiments, the first antisense compound, the second antisense compound, the third antisense compound, and optionally the fourth antisense compound each comprise a sequence substantially complementary to a target mRNA. In certain embodiments, the first antisense compound, the second antisense compound, the third antisense compound, and the fourth antisense compound each have different sequences. In certain embodiments, the first antisense compound, the second antisense compound, the third antisense compound, and optionally the fourth antisense compound each have substantially complementary to different target mRNA. In certain embodiments, the first antisense compound comprises a sequence substantially complementary to a first target mRNA, the second antisense compound comprises a sequence substantially complementary to a second target mRNA, and the third antisense compound comprises a sequence substantially complementary to a third target mRNA. In certain embodiments, the first antisense compound comprises a sequence substantially complementary to a first target mRNA, the second antisense compound comprises a sequence substantially complementary to a second target mRNA, the third antisense compound comprises a sequence substantially complementary to a third target mRNA, and the fourth antisense compound comprises a sequence substantially complementary to a fourth target mRNA. In certain embodiments, at least one antisense compound comprises a sequence substantially complementary to HTT mRNA. Exemplary HTT-targeting antisense compounds (such as siRNA) are described in further detail in U.S. Patent No. 9,809,817, incorporated herein by reference. In certain embodiments, at least one antisense compound comprises a sequence substantially complementary to MSH3 mRNA. Exemplary MSH3-targeting antisense compounds (such as siRNA) are described in further detail in U.S. Publication No. 2021 / 0355491 A1, incorporated herein by reference. In certain embodiments, at least one antisense compound comprises a sequence substantially complementary to MLH1 mRNA. Exemplary MLH1-targeting antisense compounds (such as siRNA) are described in further detail in U.S. Publication No. 2023 / 0340475 A1, incorporated herein by reference. In certain embodiments, at least one antisense compound comprises a sequence substantially complementary to HTT1a mRNA. Exemplary HTT1a-targeting antisense compounds (such as siRNA) are described in further detail in U.S. Publication No. 2022 / 0090069 A1 and WO2023 / 014654 A2, each incorporated herein by reference. In certain embodiments, at least one antisense compound comprises a sequence substantially complementary to FAN1 mRNA. In certain embodiments, at least one antisense compound comprises a sequence substantially complementary to MECP2 mRNA. Exemplary MECP2-targeting antisense compounds (such as siRNA) are described in further detail in U.S. Publication No. 2023 / 0348907A1, incorporated herein by reference. In certain embodiments, at least one antisense compound comprises a sequence substantially complementary to JAK1 mRNA. Exemplary JAK1-targeting antisense compounds (such as siRNA) are described in further detail in WO2022 / 271666 A1, incorporated herein by reference. In certain embodiments, the first antisense compound, the second antisense compound, the third antisense compound, and optionally the fourth antisense compound each comprise a sequence substantially complementary to a HTT mRNA. In certain embodiments, the first antisense compound, the second antisense compound, the third antisense compound, and optionally the fourth antisense compound each comprise a sequence substantially complementary to a JAK1 mRNA. In certain embodiments, the first antisense compound, the second antisense compound, the third antisense compound, and optionally the fourth antisense compound each comprise a sequence substantially complementary to a MECP2 mRNA. In certain embodiments, the first antisense compound, the second antisense compound, the third antisense compound, and optionally the fourth antisense compound each comprise a sequence substantially complementary to a MSH3 mRNA. In certain embodiments, the first antisense compound comprises a sequence substantially complementary to a HTT mRNA, the second antisense compound comprises a sequence substantially complementary to a MSH3 mRNA, and the third antisense compound comprises a sequence substantially complementary to a JAK1 mRNA. In certain embodiments, the first antisense compound comprises a sequence substantially complementary to a HTT mRNA, the second antisense compound comprises a sequence substantially complementary to a MSH3 mRNA, the third antisense compound comprises a sequence substantially complementary to a JAK1 mRNA, and the fourth antisense compound comprises a sequence substantially complementary to a MECP2 mRNA. In certain embodiments, the polynucleotide nanostructure is capable of silencing the first target mRNA, the second target mRNA, and the third target mRNA within a single cell in an organism. In certain embodiments, the polynucleotide nanostructure is capable of silencing the first target mRNA, the second target mRNA, the third target mRNA, and the fourth mRNA within a single cell in an organism. Conjugated Functional Moieties The polynucleotide nanostructures of the disclosure may be conjugated (i.e., linked) to one or more functional moieties. In certain embodiments, one or more individual polynucleotide strands of a polynucleotide nanostructure are conjugated to a functional moiety. In certain embodiments, the functional moiety is conjugated to the 5’ end of an individual polynucleotide strand. In certain embodiments, the functional moiety is conjugated to the 3’ end of an individual polynucleotide strand. A functional moiety is a molecule that confers one or more additional activities to the polynucleotide nanostructure. In certain embodiments, the functional moieties enhance cellular uptake by target cells (e.g., neuronal cells). Thus, the disclosure includes polynucleotide nanostructures which are conjugated or unconjugated to another moiety (e.g. a non-nucleic acid moiety such as a peptide), an organic compound (e.g., a dye), or the like. The conjugation can be accomplished by methods known in the art, e.g., using the methods of Lambert et al., Drug Deliv. Rev.: 47(1), 99-112 (2001) (describes nucleic acids loaded to polyalkylcyanoacrylate (PACA) nanoparticles); Fattal et al., J. Control Release 53(1-3):137- 43 (1998) (describes nucleic acids bound to nanoparticles); Schwab et al., Ann. Oncol.5 Suppl. 4:55-8 (1994) (describes nucleic acids linked to intercalating agents, hydrophobic groups, polycations or PACA nanoparticles); and Godard et al., Eur. J. Biochem.232(2):404-10 (1995) (describes nucleic acids linked to nanoparticles). In a certain embodiment, the functional moiety is a hydrophobic moiety. In a certain embodiment, the hydrophobic moiety is selected from the group consisting of fatty acids, steroids, secosteroids, lipids, gangliosides and nucleoside analogs, endocannabinoids, and vitamins. In a certain embodiment, the steroid selected from the group consisting of cholesterol and Lithocholic acid (LCA). In a certain embodiment, the fatty acid selected from the group consisting of Eicosapentaenoic acid (EPA), Docosahexaenoic acid (DHA) and Docosanoic acid (DCA). In a certain embodiment, the vitamin selected from the group consisting of choline, vitamin A, vitamin E, and derivatives or metabolites thereof. In a certain embodiment, the vitamin is selected from the group consisting of retinoic acid and alpha-tocopheryl succinate. In a certain embodiment, a polynucleotide nanostructure of disclosure is conjugated to a lipophilic moiety. In one embodiment, the lipophilic moiety is a ligand that includes a cationic group. In another embodiment, the lipophilic moiety is attached to the polynucleotide nanostructure. In certain embodiments, the lipophilic moiety is selected from the group consisting of cholesterol, vitamin E, vitamin K, vitamin A, folic acid, a cationic dye (e.g., Cy3). In an exemplary embodiment, the lipophilic moiety is cholesterol. Other lipophilic moieties include cholic acid, adamantane acetic acid, 1-pyrene butyric acid, dihydrotestosterone, 1,3- Bis-O(hexadecyl)glycerol, geranyloxyhexyl group, hexadecylglycerol, borneol, menthol, 1,3- propanediol, heptadecyl group, palmitic acid, myristic acid, O3-(oleoyl)lithocholic acid, O3- (oleoyl)cholenic acid, dimethoxytrityl, or phenoxazine. In certain embodiments, the functional moieties may comprise one or more ligands tethered to a polynucleotide nanostructure to improve stability, hybridization thermodynamics with a target nucleic acid, targeting to a particular tissue or cell-type, or cell permeability, e.g., by an endocytosis-dependent or -independent mechanism. Ligands and associated modifications can also increase sequence specificity and consequently decrease off-site targeting. Exemplary ligands are coupled, either directly or indirectly, via an intervening tether, to a ligand-conjugated carrier. In certain embodiments, the coupling is through a covalent bond. In certain embodiments, the ligand is attached to the carrier via an intervening tether. In certain embodiments, a ligand alters the distribution, targeting or lifetime of a polynucleotide nanostructure into which it is incorporated. In certain embodiments, a ligand provides an enhanced affinity for a selected target, e.g., molecule, cell or cell type, compartment, e.g., a cellular or organ compartment, tissue, organ or region of the body, as, e.g., compared to a species absent such a ligand. Exemplary ligands can improve transport, hybridization, and specificity properties and may also improve nuclease resistance of the resultant polynucleotide nanostructure, or a polymeric molecule comprising any combination of monomers described herein and / or natural or modified ribonucleotides. Ligands in general can include therapeutic modifiers, e.g., for enhancing uptake; diagnostic compounds or reporter groups e.g., for monitoring distribution; cross-linking agents; nuclease-resistance conferring moieties; and natural or unusual nucleobases. General examples include lipophiles, lipids, steroids (e.g., uvaol, hecigenin, diosgenin), terpenes (e.g., triterpenes, e.g., sarsasapogenin, Friedelin, epifriedelanol derivatized lithocholic acid), vitamins (e.g., folic acid, vitamin A, biotin, pyridoxal), carbohydrates, proteins, protein binding agents, integrin targeting molecules, polycationics, peptides, polyamines, and peptide mimics. Ligands can include a naturally occurring substance, (e.g., human serum albumin (HSA), low-density lipoprotein (LDL), or globulin); carbohydrate (e.g., a dextran, pullulan, chitin, chitosan, inulin, cyclodextrin or hyaluronic acid); amino acid, or a lipid. The ligand may also be a recombinant or synthetic molecule, such as a synthetic polymer, e.g., a synthetic polyamino acid. Examples of polyamino acids include polyamino acid is a polylysine (PLL), poly L-aspartic acid, poly L-glutamic acid, styrene-maleic acid anhydride copolymer, poly(L-lactide-co-glycolied) copolymer, divinyl ether-maleic anhydride copolymer, N-(2-hydroxypropyl)methacrylamide copolymer (HMPA), polyethylene glycol (PEG), polyvinyl alcohol (PVA), polyurethane, poly(2-ethylacryllic acid), N- isopropylacrylamide polymers, or polyphosphazine. Example of polyamines include: polyethylenimine, polylysine (PLL), spermine, spermidine, polyamine, pseudopeptide- polyamine, peptidomimetic polyamine, dendrimer polyamine, arginine, amidine, protamine, cationic lipid, cationic porphyrin, quaternary salt of a polyamine, or an alpha helical peptide. Ligands can also include targeting groups, e.g., a cell or tissue targeting agent, e.g., a lectin, glycoprotein, lipid or protein, e.g., an antibody, that binds to a specified cell type such as a kidney cell or a muscle cell. A targeting group can be a thyrotropin, melanotropin, lectin, glycoprotein, surfactant protein A, mucin carbohydrate, multivalent lactose, multivalent galactose, N-acetyl-galactosamine (GalNAc) or derivatives thereof, N-acetyl-glucosamine, multivalent mannose, multivalent fucose, glycosylated polyaminoacids, multivalent galactose, transferrin, bisphosphonate, polyglutamate, polyaspartate, a lipid, cholesterol, a steroid, bile acid, folate, vitamin B12, biotin, or an RGD peptide or RGD peptide mimetic. Other examples of ligands include dyes, intercalating agents (e.g. acridines and substituted acridines), cross- linkers (e.g. psoralene, mitomycin C), porphyrins (TPPC4, texaphyrin, Sapphyrin), polycyclic aromatic hydrocarbons (e.g., phenazine, dihydrophenazine, phenanthroline, pyrenes), lys-tyr- lys tripeptide, aminoglycosides, guanidium aminoglycodies, artificial endonucleases (e.g. EDTA), lipophilic molecules, e.g, cholesterol (and thio analogs thereof), cholic acid, cholanic acid, lithocholic acid, adamantane acetic acid, 1-pyrene butyric acid, dihydrotestosterone, glycerol (e.g., esters (e.g., mono, bis, or tris fatty acid esters, e.g., C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, or C20fatty acids) and ethers thereof, e.g., C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, or C20alkyl; e.g., 1,3-bis-O(hexadecyl)glycerol, 1,3-bis-O(octaadecyl)glycerol), geranyloxyhexyl group, hexadecylglycerol, borneol, menthol, 1,3-propanediol, heptadecyl group, palmitic acid, stearic acid (e.g., glyceryl distearate), oleic acid, myristic acid, O3- (oleoyl)lithocholic acid, O3-(oleoyl)cholenic acid, dimethoxytrityl, or phenoxazine) and peptide conjugates (e.g., antennapedia peptide, Tat peptide), alkylating agents, phosphate, amino, mercapto, PEG (e.g., PEG-40K), MPEG, [MPEG]2, polyamino, alkyl, substituted alkyl, radiolabeled markers, enzymes, haptens (e.g. biotin), transport / absorption facilitators (e.g., aspirin, naproxen, vitamin E, folic acid), synthetic ribonucleases (e.g., imidazole, bisimidazole, histamine, imidazole clusters, acridine-imidazole conjugates, Eu3+complexes of tetraazamacrocycles), dinitrophenyl, HRP or AP. In certain embodiments, the ligand is GalNAc or a derivative thereof. Ligands can be proteins, e.g., glycoproteins, or peptides, e.g., molecules having a specific affinity for a co-ligand, or antibodies e.g., an antibody, that binds to a specified cell type such as a cancer cell, endothelial cell, or bone cell. Ligands may also include hormones and hormone receptors. They can also include non-peptidic species, such as lipids, lectins, carbohydrates, vitamins, cofactors, multivalent lactose, multivalent galactose, N-acetyl- galactosamine, N-acetyl-glucosamine multivalent mannose, or multivalent fucose. The ligand can be, for example, a lipopolysaccharide, an activator of p38 MAP kinase, or an activator of NF-kB. The ligand can be a substance, e.g., a drug, which can increase the uptake of the a polynucleotide nanostructure into the cell, for example, by disrupting the cell's cytoskeleton, e.g., by disrupting the cell's microtubules, microfilaments, and / or intermediate filaments. The drug can be, for example, taxon, vincristine, vinblastine, cytochalasin, nocodazole, japlakinolide, latrunculin A, phalloidin, swinholide A, indanocine, or myoservin. The ligand can increase the uptake of the a polynucleotide nanostructure into the cell by activating an inflammatory response, for example. Exemplary ligands that would have such an effect include tumor necrosis factor alpha (TNFα), interleukin-1 beta, or gamma interferon. In one aspect, the ligand is a lipid or lipid-based molecule. Such a lipid or lipid-based molecule can bind a serum protein, e.g., human serum albumin (HSA). An HSA binding ligand allows for distribution of the conjugate to a target tissue, e.g., a non-kidney target tissue of the body. For example, the target tissue can be the liver, including parenchymal cells of the liver. Other molecules that can bind HSA can also be used as ligands. For example, neproxin or aspirin can be used. A lipid or lipid-based ligand can (a) increase resistance to degradation of the conjugate, (b) increase targeting or transport into a target cell or cell membrane, and / or (c) can be used to adjust binding to a serum protein, e.g., HSA. A lipid based ligand can be used to modulate, e.g., control the binding of the conjugate to a target tissue. For example, a lipid or lipid-based ligand that binds to HSA more strongly will be less likely to be targeted to the kidney and therefore less likely to be cleared from the body. A lipid or lipid-based ligand that binds to HSA less strongly can be used to target the conjugate to the kidney. In a certain embodiment, the lipid based ligand binds HSA. A lipid-based ligand can bind HSA with a sufficient affinity such that the conjugate will be distributed to a non-kidney tissue. However, it is contemplated that the affinity not be so strong that the HSA-ligand binding cannot be reversed. In another embodiment, the lipid based ligand binds HSA weakly or not at all, such that the conjugate will be distributed to the kidney. Other moieties that target to kidney cells can also be used in place of or in addition to the lipid based ligand. In another aspect, the ligand is a moiety, e.g., a vitamin, which is taken up by a target cell, e.g., a proliferating cell. These can be useful for treating disorders characterized by unwanted cell proliferation, e.g., of the malignant or non-malignant type, e.g., cancer cells. Exemplary vitamins include vitamin A, E, and K. Other exemplary vitamins include are B vitamin, e.g., folic acid, B12, riboflavin, biotin, pyridoxal or other vitamins or nutrients taken up by cancer cells. Also included are HSA and low density lipoprotein (LDL). In another aspect, the ligand is a cell-permeation agent, such as a helical cell-permeation agent. In certain embodiments, the agent is amphipathic. An exemplary agent is a peptide such as tat or antennopedia. If the agent is a peptide, it can be modified, including a peptidylmimetic, invertomers, non-peptide or pseudo-peptide linkages, and use of D-amino acids. The helical agent can be an alpha-helical agent, which may have a lipophilic and a lipophobic phase. The ligand can be a peptide or peptidomimetic. A peptidomimetic (also referred to herein as an oligopeptidomimetic) is a molecule capable of folding into a defined three- dimensional structure similar to a natural peptide. The attachment of peptide and peptidomimetics to oligonucleotide agents can affect pharmacokinetic distribution of the RNA silencing agent, such as by enhancing cellular recognition and absorption. The peptide or peptidomimetic moiety can be about 5-50 amino acids long, e.g., about 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50 amino acids long. A peptide or peptidomimetic can be, for example, a cell permeation peptide, cationic peptide, amphipathic peptide, or hydrophobic peptide (e.g., consisting primarily of Tyr, Trp or Phe). The peptide moiety can be a dendrimer peptide, constrained peptide or crosslinked peptide. The peptide moiety can be an L-peptide or D- peptide. In another alternative, the peptide moiety can include a hydrophobic membrane translocation sequence (MTS). A peptide or peptidomimetic can be encoded by a random sequence of DNA, such as a peptide identified from a phage-display library, or one-bead-one- compound (OBOC) combinatorial library (Lam et al., Nature 354:82-84, 1991). In exemplary embodiments, the peptide or peptidomimetic tethered to an RNA silencing agent via an incorporated monomer unit is a cell targeting peptide such as an arginine-glycine-aspartic acid (RGD)-peptide, or RGD mimic. A peptide moiety can range in length from about 5 amino acids to about 40 amino acids. The peptide moieties can have a structural modification, such as to increase stability or direct conformational properties. Any of the structural modifications described below can be utilized. In certain embodiments, the functional moiety is linked to the polynucleotide nanostructure by a linker. In certain embodiments, the functional moiety is linked to an individual polynucleotide strand of the polynucleotide nanostructure by a linker. In certain embodiments, the linker comprises a divalent or trivalent linker. In certain embodiments, the linker comprises an ethylene glycol chain, an alkyl chain, a peptide, RNA, DNA, a phosphodiester, a phosphorothioate, a phosphoramidate, an amide, a carbamate, or a combination thereof. In certain embodiments, the divalent or trivalent linker is selected from: wherein n is 1, 2, 3, 4, or 5. In certain embodiments, the linker further comprises a phosphodiester or phosphodiester derivative. In certain embodiments, the phosphodiester or phosphodiester derivative is selected from the group consisting of: wherein X is O, S or BH3. The various functional moieties of the disclosure and means to conjugate them to polynucleotide nanostructures are described in further detail in WO2017 / 030973A1 and WO2018 / 031933A2, incorporated herein by reference. Methods of Delivery / Treatment with Polynucleotide Nanostructures The polynucleotide nanostructures of the disclosure may be administered to a subject for tissue and cell specific delivery. The polynucleotide nanostructures are relatively large, with molecular weights that reduce kidney clearance rates. Exemplary polynucleotide nanostructures described herein were capable of robust tissue accumulation and silencing and in several tissues, including various brain tissues (frontal cortex, striatum, thalamus, hippocampus, medial cortex, posterior cortex, cerebellum, and brain stem), heart, lung, liver, and kidney. Accordingly, the disclosure provides a method of silencing one or more different target mRNA in a cell of a subject, the method comprising administering to the subject the polynucleotide nanostructure describe. In certain embodiments, the polynucleotide nanostructure is administered the central nervous system of the subject and the cell is a cell of the central nervous system. In certain embodiments, the polynucleotide nanostructure is administered via intracerebroventricular (ICV) injection or intrastriatal (IS) injection. In certain embodiments, the polynucleotide nanostructure is administered systemically to the subject and the cell is a kidney cell. In certain embodiments, the polynucleotide nanostructure is administered systemically to the subject and the cell is a heart cell. In certain embodiments, the polynucleotide nanostructure is administered via intravenous (IV) injection or subcutaneous (SQ) injection. In certain embodiments, the polynucleotide nanostructure is administered to a lung of subject and the cell is a lung cell. In another aspect, the disclosure provides a method of treating or managing a neurodegenerative disease comprising administering to a subject in need of such treatment a therapeutically effective amount of said polynucleotide nanostructure described herein, thereby treating or managing the neurodegenerative disease. In another aspect, the disclosure provides a method of treating or managing a kidney disease comprising administering to a subject in need of such treatment a therapeutically effective amount of said polynucleotide nanostructure described herein, thereby treating or managing the kidney disease. In another aspect, the disclosure provides a method of treating or managing a lung disease comprising administering to a subject in need of such treatment a therapeutically effective amount of said polynucleotide nanostructure described herein, thereby treating or managing the lung disease.

[0007] EXAMPLES EXAMPLE 1 – TRIANGLE & SQUARE POLYNUCLEOTIDE NANOSTRUCTURES Polynucleotide nanostructures are potentially useful for the delivery of therapeutic agents, including siRNA. However, existing nanostructures possess complicated designs with multiple separate polynucleotide sequences of long length, which are difficult and costly to synthesize. Moreover, existing nanostructures are often unmodified or minimally chemically modified, giving them limited in vivo utility. To resolve these issues, several fully chemically modified polynucleotide nanostructures of a triangle configuration were designed and tested (see FIG.1). A summary of the four tested triangle polynucleotide nanostructures is provided below in Table 1. Table 1 – Triangle polynucleotide nanostructure configurations The four different triangle nanostructures designed to target HTT mRNA were tested in vitro in cells. HeLA cells were transfected (RNAimax) with control or triangle nanostructures to obtain a final siRNA concentration of 10 nM at the highest dose (triangle concentration is 3.34 nM as it carries 3 copies of the same siRNA). A range of concentration was also tested, going down a 10-fold dilution from the highest dose. After 72hours, cells were harvested and relative HTT expression was determined. A traditional fully modified siRNA with an identical antisense strand as employed in the different triangle nanostructures was used as a control. As shown in FIG. 2, versions V3 and V4 elicited a similar reduction in HTT mRNA levels compared to the control. Version V2, while capable of silencing HTT mRNA, required significantly higher concentrations. Version V1, not shown, did not silence HTT mRNA. The results indicate that antisense strand placement in the nanostructure is important, with better silencing activity achieve when the antisense strand is hybridized to the nanostructure scaffold (either internally or on the ends of the triangle), rather than being incorporated into the polynucleotide scaffold sequence itself. In contrast, the sense strand tolerated being incorporated into the polynucleotide scaffold. The V4 design was selected for further study. Moreover, a square polynucleotide nanostructure was also designed based on the principles of the V4 triangle design (i.e., antisense strands hybridized to the edges of the scaffold). Sequences for generating a V4 triangle nanostructure or square nanostructure are provided below in Table 2. Table 2 – Triangle and square nanostructure polynucleotide scaffold sequences In the above polynucleotide scaffold configurations, (N)xcorresponds to the portion of the polynucleotide scaffold that is complementary to the desired antisense strand, essentially serving as the sense strand. Thus, the sequence changes depending on the antisense strand used and whether the antisense strand has a single stranded tail (i.e., a portion of the antisense strand that is not hybridized to the scaffold) or if the antisense strand is hybridized to the scaffold across the entire length of the antisense strand (i.e., producing a blunt end with no single stranded tail). A blunt end arrangement does not preclude the incorporation of internal mismatches between the antisense strand and the scaffold. In the above polynucleotide scaffold configurations, (N)ycorresponds to a stretch of nucleotides that links the sense strand portion of the polynucleotide scaffold to the structural portion of the polynucleotide scaffold (i.e., the portion that forms the triangle or square). The (N)yportion may be composed of unmodified RNA nucleotides or DNA nucleotides with phosphodiester internucleotide linkages. Thus, once in a cell, the polynucleotide nanostructure will be cleaved at the (N)yportion, thus liberating the siRNA, composed of the hybridized antisense strand and the sense strand portion of the polynucleotide scaffold. In the above polynucleotide scaffold configurations, (N)zcorresponds to a stretch of nucleotides that do not hybridize with any other part of the polynucleotide nanostructure, and thus remain single stranded. Sequences used to generate the HTT-targeting V4 triangle and HTT-targeting square are shown below in Table 3. Table 3 – HTT-targeting V4 triangle and square nanostructures polynucleotide scaffold sequences Table 4 - Fully chemically modified V4 triangle polynucleotide scaffold sequences EXAMPLE 2 – MULTI-GENE TARGETING WITH TRIANGLE & SQUARE POLYNUCLEOTIDE NANOSTRUCTURES One advantage of the triangle and square polynucleotide nanostructures is the ability to target multiple different mRNA. For the triangle, 3 different mRNA may be targeted, and for the square, 4 different mRNA may be targeted. Moreover, since a single polynucleotide nanostructure molecule delivers the multiple antisense strands, all 3 or 4 mRNA may be silenced within the same cell. This is in contrast to administering 3 or 4 separate siRNA in a cocktail, where some cells may receive uneven amounts of each siRNA, or have one or more of the siRNAs be completely absent. Thus, the triangle and square polynucleotide nanostructures ensure homogenous silencing of all target mRNA in each cell that takes up the nanostructures. To test the ability to silence multiple mRNA in a single assay, a V4 triangle was designed to target HTT, MSH3, and JAK1 (i.e., a first antisense strand targeting HTT mRNA, a second antisense strand targeting MSH3 mRNA, and a third antisense strand targeting JAK1 mRNA. As shown in FIG. 3, all three targets were robustly silenced in a single assay, with comparable silencing to the HTT-targeting siRNA control. EXAMPLE 3 – IN VIVO SILENCING WITH TRIANGLE & SQUARE POLYNUCLEOTIDE NANOSTRUCTURES As noted above in Example 1, polynucleotide nanostructures that are not fully chemically modified lack therapeutic utility as the nanostructures are rapidly degraded in a subject’s serum. To test the in vivo utility of the polynucleotide nanostructures of the disclosure, the V4 triangle targeting only HTT or targeting HTT, MSH3, and JAK1 was administered to c57bl / 6 male mice (n= 3-4 mice per group, age 9-11 weeks) directly in the central nervous system (CNS) via bilateral intracerebroventricular injection (ICV) . After 2 weeks or 2 months, mouse brain tissues were harvested and tested for relative HTT expression. Three controls were also employed: a HTT-targeting siRNA, a di-branched HTT targeting compound composed to two identical HTT-targeting siRNA linked via a polyethylene glycol-based linker, and a an Arm-siRNA composed of the same HTT-targeting antisense strand hybridized to one polynucleotide scaffold arm. As shown in FIG.4A and FIG.4B, HTT was silenced to the same level as the well validated and highly effective control siRNA. Importantly, this robust silencing from the V4 triangle was observed at two-months, demonstrating a durable silencing effect. Silencing was also observed in all brain tissues tested (frontal cortex, striatum, thalamus, hippocampus, medial cortex, posterior cortex, cerebellum, and brain stem). Next the HTT / MSH3 / JAK1 multi-targeting triangle was tested in vivo, again at 2-weeks and 2-months. As shown in FIG.5A and FIG.5B, the multi-targeting triangle was capable of robustly silencing all three targets in various brain tissues. The square nanostructure was also tested in vivo for HTT silencing. As shown in FIG. 6, the square nanostructure was capable of silencing HTT in various brain tissues to a level comparable to standard siRNA, after 1 month of treatment. A square nanostructure was next designed to target 4 separate targets, HTT, MSH3, JAK1, and MECP2. This quad-targeting square nanostructure was used in vivo. As shown in FIG.7A and FIG.7B, the quad-targeting square nanostructure was capable of silencing all 4 mRNA in both the striatum and the hippocampus. Intravenous Administration The prior in vivo experiments were performed in the CNS. The triangle and square nanostructures were next tested in mice after intravenous administration. The triangle and square nanostructures were compared to a DCA-conjugated siRNA, a conjugate which promotes longer pharmacokinetics of blood clearance. Four mice per group were injected with a 20 nmol dose per active strand. FVBNJ female mice were used at 6-8 weeks old. PK measurements were takes at various time points up to 24 hours via cheek bleeds. As shown in FIG. 8, the PK properties of the triangle and square nanostructures were comparable to the DCA-siRNA, while the control arm-siRNA was rapidly cleared. Thus, the polynucleotide nanostructures of the disclosure enjoy prolonged PK without the need for a hydrophobic conjugate, which makes the siRNA more expensive to produce and requires additional chemistry steps for linking to the siRNA. Moreover, the triangle and square nanostructures accumulated in a variety of tissues while also effectively silencing HTT (see, FIG.9A and FIG.9B). Subcutaneous Administration The triangle and square nanostructures were next tested in mice with subcutaneous administration. Five FVBNJ female mice (6-8 weeks old) per group were injected with a 30 nmol dose per active strand. Silencing and tissue accumulation were determined 2-weeks post- injection, as shown in FIG.10A and FIG.10B. Silencing of the four targets HTT, MSH3, JAK1, and MECP2 from the square nanostructure was also measured in liver and heart, as shown in FIG.11A and FIG.11B. Full chemical modification compared to DNA-containing nanostructures The RNA nanostructures described herein may be fully chemically modified to enhance in vivo utility (i.e., reduce degradation and prolong silencing). To demonstrate the importance of nucleotide modification, the fully modified triangle RNA nanostructure was compared against a triangle RNA nanostructure with DNA nucleotides in the scaffold. The accompanying siRNA (antisense strand and sense strand portion of the nanostructure) of both tested triangle RNA nanostructures were fully chemically modified. Mice were injected with one of the two triangle RNA nanostructures and brain tissues were harvested two-months after injection. As shown in FIG. 12, the triangle RNA nanostructure containing unmodified DNA nucleotides had reduced silencing efficacy after two-months compared to the fully modified triangle RNA nanostructure. RNA nanostructures conjugated with functional moieties The RNA nanostructures described herein may be conjugated to a functional moiety, such as a hydrophobic moiety. Specifically, three different triangle polynucleotide nanostructures were tested with a DCA conjugate. The Tv4 structure was made to target HTT with the DCA at 3’ end of scaffold strand. FIG. 14A depicts schematics of three different triangle polynucleotide nanostructures tested for HTT silencing. Tv4 + 1xDCA contains a DCA lipid conjugate. As shown in FIG.14B, HTT silencing was measured from the three different triangle polynucleotide nanostructures shown in FIG. 14A. The data shows that both nanostructures are capable of silencing HTT mRNA, including the DCA conjugated nanostructure. The effects of 1, 2, or 3 DCA conjugates on the triangle nanostructures for silencing was next determined. Mice were subcutaneously injected with 30 nmol of the triangle nanostructures and organs were harvested 2 weeks later. HTT expression was measured in heart, lung, muscle, and liver. The tested structures were Tv43xHTT, Tv43xHTT with 1 DCA conjugate, Tv4 3xHTT with 2 DCA conjugates, Tv4 3xHTT with 3 DCA conjugates, a monovalent siRNA targeting HTT conjugated with DCA, a monovalent siRNA targeting a non- target control conjugated with DCA, and an Arm tv4 with 1 DCA conjugate. As shown in FIG. 15, relative HTT silencing of triangle polynucleotide nanostructures having 1, 2, or 3 DCA lipid conjugates was determined. It was observed that increasing the number of DCA conjugates improved silencing in the heart and decreased silencing in the liver. Effect of RNA nanostructure molecular weight The molecular weight of the RNA nanostructures described herein may be altered in various ways, including, but not limited to, altering the length of the scaffold portions of the RNA nanostructures or conjugating one or more functional moieties (e.g., DCA). Specifically, triangle polynucleotide nanostructures having varied molecular weights were designed to target HTT. The nanostructure of Tv4 (A) is about 73 kDa. The nanostructure of Tv4 size 2 (B) is about 63 kDa. The nanostructure of Tv4 size 3 (C) is about 55 kDa. Mice were injected intravenously with 20 nmol of the compounds and organs were harvested 2 weeks later. HTT expression was measured in heart, lung, muscle, liver, kidney, and spleen. Varying the molecular weight did not affect pharmacokinetic blood clearance over a period of 1500 minutes (data not shown). As shown in FIG. 16, structures of varied molecular weight did not negatively impact silencing of HTT. Separately, a square polynucleotide nanostructure was tested for relative silencing of HTT, JAK1, MECP2, and MSH3. The square polynucleotide nanostructure was compared against a combination of a monovalent siRNA targeting HTT with a DCA conjugate and a monovalent siRNA targeting JAK1 with a DCA conjugate. Mice were injected subcutaneously with 40 nmol of the compounds and organs were harvested 2 weeks later. HTT, JAK1, MECP2, and MSH3 expression was measured in heart, muscle, and fat. As shown in FIG.17, the square polynucleotide nanostructure was capable of effectively silencing all 4 targets in the three organs. RNA nanostructures in the central nervous system The RNA nanostructures described herein were tested in vivo. Relative silencing of HTT from triangle polynucleotide nanostructures with antisense compounds targeting HTT was measured. Mice were injected via bilateral intracerebroventricular (ICV) administration with 10 nmol of the compounds and brain structures were harvested 2 weeks later (FIG.18A), 2 months later (FIG.18B), and 6 months later (FIG.18C). HTT expression was measured in frontal cortex, striatum, thalamus, hippocampus, medial cortex, posterior cortex, cerebellum, and brain stem. No adverse effects were observed with the triangle nanostructure, suggesting the compounds are safe for therapeutic use. The results show that the RNA nanostructures successfully silence a target in the CNS over a long period of time.

Claims

CLAIMS 1. A polynucleotide nanostructure comprising X total polynucleotide strands of Formula I:wherein: X corresponds to an integer of at least 3 (e.g., 3-15); n corresponds to an individual polynucleotide strand of the polynucleotide nanostructure of X total polynucleotide strands;corresponds to an antisense compound;corresponds to a region of complementarity to the antisense compound in the individual polynucleotide strand;corresponds to a region of complementarity to individual polynucleotide strand of n-1 in the individual polynucleotide strand of n;corresponds to a polynucleotide scaffold portion of the individual polynucleotide strand; andcorresponds to a region of complementarity to individual polynucleotide strand of n+1 in in the individual polynucleotide strand of n; wherein individual polynucleotide strand of n = 1 (i.e., the first polynucleotide strand) and individual polynucleotide strand of n = X (i.e., the last polynucleotide strand) each comprise a region of complementarity to each other; corresponds to Linker 1, optionally wherein Linker 1 is absent; andcorresponds to Linker 2, optionally wherein Linker 2 is absent.

2. The polynucleotide nanostructure of claim 1, wherein X is 3-15.

3. The polynucleotide nanostructure of claim 1, wherein X is 3, 4, 5, or 6.

4. The polynucleotide nanostructure of any one of claims 1-3, wherein each individual polynucleotide strand is between 20 nucleotides and 120 nucleotides in length.

5. The polynucleotide nanostructure of any one of claims 1-4, wherein the region of complementarity to the antisense compound in the individual polynucleotide strand is between 4 nucleotides to 40 nucleotides in length.

6. The polynucleotide nanostructure of any one of claims 1-5, wherein the region of complementarity between individual polynucleotide strands is between 4 nucleotides to 40 nucleotides in length.

7. The polynucleotide nanostructure of any one of claims 1-6, wherein the polynucleotide scaffold portion of the individual polynucleotide strand is between 4 nucleotides to 40 nucleotides in length.

8. The polynucleotide nanostructure of any one of claims 1-7, wherein: i) the region of complementarity to the antisense compound, ii) the region of complementarity between individual polynucleotide strands, and iii) the polynucleotide scaffold portion of the individual polynucleotide strand, are identical nucleotides in length.

9. The polynucleotide nanostructure of any one of claims 1-8, wherein each antisense compound of each individual polynucleotide strand is identical.

10. The polynucleotide nanostructure of any one of claims 1-8, wherein at least one antisense compound of the polynucleotide nanostructure is different from at least one other antisense compound of the polynucleotide nanostructure.

11. The polynucleotide nanostructure of any one of claims 1-8, wherein each antisense compound of each individual polynucleotide strand is different.

12. The polynucleotide nanostructure of any one of claims 1-11, comprising a polynucleotide nanostructure of Formula II:wherein: corresponds to a first antisense compound; corresponds to a second antisense compound; andcorresponds to a third antisense compound.

13. The polynucleotide nanostructure of claim 12, wherein the individual polynucleotide strand of n = 1 comprises (N)x(N)yUCGCUUCUAGGAGAU(N)zCUUUCAACUUCACAC, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, whereinx corresponds to an integer of between 4 to 25, wherein y corresponds to an integer of between 1 to 10, wherein z corresponds to an integer of between 4 to 25.

14. The polynucleotide nanostructure of claim 12 or 13, wherein the individual polynucleotide strand of n = 2 comprises (N)x(N)yGUGUGAAGUUGAAAG(N)zGUGAUGUCAUCAAUG, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, wherein y corresponds to an integer of between 1 to 10, wherein z corresponds to an integer of between 4 to 25.

15. The polynucleotide nanostructure of any one of claims 12-14, wherein the individual polynucleotide strand of n = 3 comprises (N)x(N)yCAUUGAUGACAUCAC(N)zAUCUCCUAGAAGCGA, wherein each N individually corresponds to any one of the nucleotides, wherein x corresponds to an integer of between 4 to 25, wherein y corresponds to an integer of between 1 to 10, wherein z corresponds to an integer of between 4 to 25.

16. The polynucleotide nanostructure of any one of claims 12-15, wherein x corresponds to an integer of 15, wherein y corresponds to an integer of 2, and wherein z corresponds to an integer of 12.

17. The polynucleotide nanostructure of any one of claims 1-15, wherein the individual polynucleotide strand of n = 1 comprises (N)x(N)yUCGCUUCUAGGAGAUUUAUUGACACUUCUUUCAACUUCACAC, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, and wherein y corresponds to an integer of between 1 to 10.

18. The polynucleotide nanostructure of any one of claims 1-15, wherein the individual polynucleotide strand of n = 2 comprises (N)x(N)yGUGUGAAGUUGAAAGUUAUUGACACUUGUGAUGUCAUCAAUG, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, and wherein y corresponds to an integer of between 1 to 10.

19. The polynucleotide nanostructure of any one of claims 1-15, wherein the individual polynucleotide strand of n = 3 comprises (N)x(N)yCAUUGAUGACAUCACUUAUUGACACUUAUCUCCUAGAAGCGA, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, and wherein y corresponds to an integer of between 1 to 10.

20. The polynucleotide nanostructure of any one of claims 1-11, comprising Formula III:wherein: corresponds to a first antisense compound; corresponds to a second antisense compound; corresponds to a third antisense compound; andcorresponds to a fourth antisense compound.

21. The polynucleotide nanostructure of claim 20, wherein the individual polynucleotide strand of n = 1 comprises (N)x(N)yUCGCUUCUAGGAGAU(N)zCUUUCAACUUCACAC, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, whereinx corresponds to an integer of between 4 to 25, wherein y corresponds to an integer of between 1 to 10, wherein z corresponds to an integer of between 4 to 25.

22. The polynucleotide nanostructure of 20 or 21, the individual polynucleotide strand of n = 2 comprises (N)x(N)yGUGUGAAGUUGAAAG(N)zGUGAUGUCAUCAAUG, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, wherein y corresponds to an integer of between 1 to 10, wherein z corresponds to an integer of between 4 to 25.

23. The polynucleotide nanostructure of any one of claims 20-22, wherein the individual polynucleotide strand of n = 3 comprises (N)x(N)yCAUUGAUGACAUCAC(N)zCAGCAAACCUUACUC, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, wherein y corresponds to an integer of between 1 to 10, wherein z corresponds to an integer of between 4 to 25.

24. The polynucleotide nanostructure of any one of claims 20-23, wherein the individual polynucleotide strand of n = 4 comprises (N)x(N)yGAGUAAGGUUUGCUG(N)zAUCUCCUAGAAGCGA, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, wherein y corresponds to an integer of between 1 to 10, wherein z corresponds to an integer of between 4 to 25.

25. The polynucleotide nanostructure of any one of claims 21-24, wherein x corresponds to an integer of 15, wherein y corresponds to an integer of 2, and wherein z corresponds to an integer of 12.

26. The polynucleotide nanostructure of any one of claims 20-25, wherein the individual polynucleotide strand of n = 1 comprises (N)x(N)yUCGCUUCUAGGAGAUUUAUUGACACUUCUUUCAACUUCACAC, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, and wherein y corresponds to an integer of between 1 to 10.

27. The polynucleotide nanostructure of any one of claims 20-26, wherein the individual polynucleotide strand of n = 2 comprises (N)x(N)yGUGUGAAGUUGAAAGUUAUUGACACUUGUGAUGUCAUCAAUG, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, and wherein y corresponds to an integer of between 1 to 10.

28. The polynucleotide nanostructure of any one of claims 20-27, wherein the individual polynucleotide strand of n = 3 comprises (N)x(N)yCAUUGAUGACAUCACUUAUUGACACUUCAGCAAACCUUACUC, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, and wherein y corresponds to an integer of between 1 to 10.

29. The polynucleotide nanostructure of any one of claims 20-28, wherein the individual polynucleotide strand of n = 4 comprises (N)x(N)yGAGUAAGGUUUGCUGUUAUUGACACUUAUCUCCUAGAAGCGA, wherein each N individually corresponds to any one of the nucleotides A, G, C, or U, wherein x corresponds to an integer of between 4 to 25, and wherein y corresponds to an integer of between 1 to 10.

30. The polynucleotide nanostructure of any one of claims 1-29, wherein at least one polynucleotide scaffold portion of the individual polynucleotide strand comprises an additional antisense compound hybridized to the polynucleotide scaffold portion.

31. The polynucleotide nanostructure of any one of claims 1-29, wherein each polynucleotide scaffold portion of each individual polynucleotide strand comprises an additional antisense compound hybridized to the polynucleotide scaffold portion.

32. A polynucleotide nanostructure comprising X total polynucleotide strands of FormulaIV:wherein:X corresponds to an integer of at least 3 (e.g., 3-15); n corresponds to an individual polynucleotide strand of the polynucleotide nanostructure of X total polynucleotide strands;corresponds to an antisense compound; corresponds to a region of complementarity to the antisense compound in theindividual polynucleotide strand; corresponds to a region of complementarity to individual polynucleotidestrand of n-1 in the individual polynucleotide strand of n; corresponds to a region of complementarity to individual polynucleotidestrand of n+1 in in the individual polynucleotide strand of n; wherein individual polynucleotide strand of n = 1 (i.e., the first polynucleotide strand) and individual polynucleotide strand of n = X (i.e., the last polynucleotide strand) each comprise a region of complementarity to each other; corresponds to Linker 1, optionally wherein Linker 1 is absent; and corresponds to Linker 2, optionally wherein Linker 2 is absent.

33. The polynucleotide nanostructure of claim 32, wherein X is 3-15.

34. The polynucleotide nanostructure of claim 32, wherein X is 3, 4, 5, or 6.

35. The polynucleotide nanostructure of claim 32, comprising polynucleotide nanostructure of Formula V:wherein: corresponds to a first antisense compound; corresponds to a second antisense compound; andcorresponds to a third antisense compound.

36. The polynucleotide nanostructure of any one of claims 1-35, wherein the Linker 1 and / or the Linker 2 comprises an ethylene glycol chain, an alkyl chain, a peptide, an RNA, a DNA, a phosphodiester, a phosphorothioate, a phosphoramidate, an amide, a carbamate, or a combination thereof.

37. The polynucleotide nanostructure of any one of claims 1-36, wherein the Linker 1 and / or the Linker 2comprises a cleavable linker.

38. The polynucleotide nanostructure of claim 37, wherein the cleavable linker comprises a phosphodiester linkage, a disulfide linkage, an acid-labile linkage, or a photocleavable linkage.

39. The polynucleotide nanostructure of claim 37 or 38, wherein the cleavable linker comprises a dNdN dinucleotide with phosphodiester intemucleotide linkages, wherein each dN individually corresponds to a deoxyribonucleotide of A, T, G, or C.

40. The polynucleotide nanostructure of claim 38, wherein the acid-labile linkage comprises a β-thiopropionate linkage or a carboxy dimethylmaleic anhydride (CDM) linkage.

41. The polynucleotide nanostructure of any one of claims 1-40, wherein the polynucleotide nanostructure is an RNA nanostructure.

42. The polynucleotide nanostructure of claim 41, wherein the RNA nanostructure comprises at least one modified nucleotide.

43. The polynucleotide nanostructure of claim 42, wherein the at least one modified nucleotide comprises a modification of a ribose group, a nucleobase, or a combination thereof.

44. The polynucleotide nanostructure of claim 43, wherein the modification of the ribose group is independently selected from the group consisting of 2'-O-methyl, 2’ -fluoro, 2’-O-(2- methoxy ethyl) (MOE), 2’-NH2 (2’-amino), a bicyclic nucleotide, a locked nucleic acid (LNA), a 2’-(S)-constrained ethyl (S-cEt), a constrained MOE, and a 2'-O,4'-C- aminomethylene bridged nucleic acid (2',4'-BNANC).

45. The polynucleotide nanostructure of claim 43 or 44, wherein at least 80% of the ribose groups are chemically modified.

46. The polynucleotide nanostructure of claim 43 or 44, wherein at least 90% of the ribose groups are chemically modified.

47. The polynucleotide nanostructure of claim 43 or 44, wherein 100% of the ribose groups are chemically modified.

48. The polynucleotide nanostructure of any one of claims 43-47, wherein the modification of the nucleobase is independently selected from the group consisting of 2- thiouridine, 4-thiouridine, N6-methyladenosine, pseudouridine, 2,6-diaminopurine, inosine, thymidine, 5-methylcytosine, 5-substituted pyrimidine, isoguanine, isocytosine, or halogenated aromatic groups.

49. The polynucleotide nanostructure of any one of claims 41-48, wherein the RNA nanostructure comprises at least one modified intemucleotide linkage.

50. The polynucleotide nanostructure of claim 49, wherein the at least one modified internucleotide linkage comprises a phosphorothioate intemucleotide linkage.

51. The polynucleotide nanostructure of any one of claims 1-50, wherein the antisense compound is an antisense strand of an siRNA, an antisense oligonucleotide (ASO), a microRNA, a short hairpin RNA (shRNA), an aptamer, or a combination thereof.

52. The polynucleotide nanostructure of any one of claims 1-51, wherein the antisense compound comprises a 5’ end and a 3’ end.

53. The polynucleotide nanostructure of claim 51 or 52, wherein the antisense strand comprises between 15 nucleotides to 25 nucleotides in length.

54. The polynucleotide nanostructure of any one of claims 51-53, wherein the antisense strand comprises a single stranded nucleotide overhang.

55. The polynucleotide nanostructure of any one of claims 51-54, wherein the antisense strand comprises a single stranded nucleotide overhang at the antisense strand 3’ end.

56. The polynucleotide nanostructure of any one of claims 51-55, wherein the antisense strand comprises a 2 -nucleotide to 5-nucleotide single stranded nucleotide overhang.

57. The polynucleotide nanostructure of any one of claims 54-56, wherein the single stranded nucleotide overhang lacks complementarity to the polynucleotide nanostructure.

58. The polynucleotide nanostructure of any one of claims 51-53, wherein the antisense strand forms a blunt end with the polynucleotide scaffold.

59. The polynucleotide nanostructure of any one of claims 51-58, wherein the antisense strand comprises a 5’ phosphate, a 5 ’-alkyl phosphonate, a 5’ alkylene phosphonate, or a 5’ alkenyl phosphonate.

60. The polynucleotide nanostructure of any one of claims 51-59, wherein the antisense strand comprises a 5’ vinyl phosphonate.

61. The polynucleotide nanostructure of any one of claims 51-60, wherein the antisense compound (e.g., antisense strand) comprises at least one modified nucleotide.

62. The polynucleotide nanostructure of claim 61, wherein the at least one modified nucleotide comprises a modification of a ribose group, a nucleobase, or a combination thereof.

63. The polynucleotide nanostructure of claim 62, wherein the modification of the ribose group is independently selected from the group consisting of 2'-O-methyl, 2’ -fluoro, 2’-O-(2- methoxy ethyl) (MOE), 2’-NH2 (2’-amino), a bicyclic nucleotide, a locked nucleic acid (LNA), a 2’-(S)-constrained ethyl (S-cEt), a constrained MOE, and a 2'-O,4'-C- aminomethylene bridged nucleic acid (2',4'-BNANC).

64. The polynucleotide nanostructure of claim 62 or 63, wherein at least 80% of the ribose groups are chemically modified.

65. The polynucleotide nanostructure of claim 62 or 63, wherein at least 90% of the ribose groups are chemically modified.

66. The polynucleotide nanostructure of claim 62 or 63, wherein 100% of the ribose groups are chemically mo67. The polynucleotide nanostructure of any one of claims 62-66, wherein the modification of the nucleobase is independently selected from the group consisting of 2- thiouridine, 4-thiouridine, N6-methyladenosine, pseudouridine, 2,6-diaminopurine, inosine, thymidine, 5-methylcytosine, 5-substituted pyrimidine, isoguanine, isocytosine, or halogenated aromatic groups.

68. The polynucleotide nanostructure of any one of claims 51-67, wherein the antisense compound (e.g., antisense strand) comprises at least one modified internucleotide linkage.

69. The polynucleotide nanostructure of claim 68, wherein the at least one modified internucleotide linkage comprises a phosphorothioate intemucleotide linkage.

70. The polynucleotide nanostructure of any one of claims 1-69, wherein the first antisense compound, the second antisense compound, the third antisense compound, and the fourth antisense compound each comprise a sequence substantially complementary to a target mRNA.

71. The polynucleotide nanostructure of any one of claims 1-70, wherein the first antisense compound, the second antisense compound, the third antisense compound, and the fourth antisense compound each have different sequences.

72. The polynucleotide nanostructure of any one of claims 1-70, wherein the first antisense compound, the second antisense compound, the third antisense compound, and optionally the fourth antisense compound each have substantially complementary to different target mRNA.

73. The polynucleotide nanostructure of any one of claims 1-70, wherein the first antisense compound comprises a sequence substantially complementary to a first target mRNA, the second antisense compound comprises a sequence substantially complementary to a second target mRNA, and the third antisense compound comprises a sequence substantially complementary to a third target mRNA.

74. The polynucleotide nanostructure of any one of claims 1-70, wherein the first antisense compound comprises a sequence substantially complementary to a first target mRNA, the second antisense compound comprises a sequence substantially complementary to a second target mRNA, the third antisense compound comprises a sequence substantially complementary to a third target mRNA, and the fourth antisense compound comprises a sequence substantially complementary to a fourth target mRNA.

75. The polynucleotide nanostructure of any one of claims 1-70, wherein the first antisense compound, the second antisense compound, the third antisense compound, and optionally the fourth antisense compound each comprise a sequence substantially complementary to a HTT mRNA.

76. The polynucleotide nanostructure of any one of claims 1-70, wherein the first antisense compound, the second antisense compound, the third antisense compound, and optionally the fourth antisense compound each comprise a sequence substantially complementary to a JAK1 mRNA.

77. The polynucleotide nanostructure of any one of claims 1-70, wherein the first antisense compound, the second antisense compound, the third antisense compound, and optionally the fourth antisense compound each comprise a sequence substantially complementary to a MECP2 mRNA.

78. The polynucleotide nanostructure of any one of claims 1-70, wherein the first antisense compound, the second antisense compound, the third antisense compound, and optionally the fourth antisense compound each comprise a sequence substantially complementary to a MSH3 mRNA.

79. The polynucleotide nanostructure of any one of claims 1-70, wherein the first antisense compound comprises a sequence substantially complementary to a HTT mRNA, the second antisense compound comprises a sequence substantially complementary to a MSH3 mRNA, and the third antisense compound comprises a sequence substantially complementary to a JAK1 mRNA.

80. The polynucleotide nanostructure of any one of claims 1-70, wherein the first antisense compound comprises a sequence substantially complementary to a HTT mRNA, the second antisense compound comprises a sequence substantially complementary to a MSH3 mRNA, the third antisense compound comprises a sequence substantially complementary to a JAK1 mRNA, and the fourth antisense compound comprises a sequence substantially complementary to a MECP2 mRNA.

81. The polynucleotide nanostructure of any one of claims 71-80, capable of silencing the first target mRNA, the second target mRNA, and the third target mRNA within a single cell in an organism.

82. The polynucleotide nanostructure of any one of claims 71-81, capable of silencing the first target mRNA, the second target mRNA, the third target mRNA, and the fourth mRNA within a single cell in an organism.

83. A pharmaceutical composition comprising the polynucleotide nanostructure of any one of claims 1-82 and a pharmaceutically acceptable carrier.

84. A method of silencing one or more different target mRNA in a cell of a subject, the method comprising administering to the subject the polynucleotide nanostructure of any one of claims 1-82.

85. The method of claim 84, wherein the polynucleotide nanostructure is administered the central nervous system of the subject and the cell is a cell of the central nervous system.

86. The method of claim 85, wherein the polynucleotide nanostructure is administered via intracerebroventricular (ICV) injection or intrastriatal (IS) injection.

87. The method of claim 84, wherein the polynucleotide nanostructure is administered systemically to the subject and the cell is a kidney cell, a muscle cell, a heart cell, a skin cell, and / or an adipose cell.

88. The method of claim 87, wherein the polynucleotide nanostructure is administered via intravenous (IV) injection89. The method of claim 84, wherein the polynucleotide nanostructure is administered to a lung of subject and the cell is a lung cell.

90. A method of treating or managing a neurodegenerative disease comprising administering to a subject in need of such treatment a therapeutically effective amount of said polynucleotide nanostructure of any one of claims 1-82, thereby treating or managing the neurodegenerative disease.

91. A method of treating or managing a kidney disease comprising administering to a subject in need of such treatment a therapeutically effective amount of said polynucleotide nanostructure of any one of claims 1-82, thereby treating or managing the kidney disease.

92. A method of treating or managing a lung disease comprising administering to a subject in need of such treatment a therapeutically effective amount of said polynucleotide nanostructure of any one of claims 1-82, thereby treating or managing the lung disease.

93. A method of treating or managing a heart disease comprising administering to a subject in need of such treatment a therapeutically effective amount of said polynucleotide nanostructure of any one of claims 1-82, thereby treating or managing the heart disease.

94. A method of treating or managing a muscle disease comprising administering to a subject in need of such treatment a therapeutically effective amount of said polynucleotide nanostructure of any one of claims 1-82, thereby treating or managing the muscle disease.

95. A method of treating or managing a skin disease comprising administering to a subject in need of such treatment a therapeutically effective amount of said polynucleotide nanostructure of any one of claims 1-82, thereby treating or managing the skin disease.

96. A method of treating or managing a disease of adipose tissue comprising administering to a subject in need of such treatment a therapeutically effective amount of said polynucleotide nanostructure of any one of claims 1-82, thereby treating or managing the disease of adipose tissue.