PERK protein mutant and its application in preventing UVB-induced skin photodamage response

Abstract

The present invention provides a PERK protein mutant and its application in preventing UVB-induced skin photodamage response, its encoding nucleic acid, a recombinant vector containing its encoding nucleic acid, a recombinant host cell containing the recombinant vector, and primers for amplifying its encoding nucleic acid. The present invention discloses that a mutant with a truncated C-terminus of the PERK protein can antagonize the activation of the p53-PERP pathway and the pro-apoptotic effect induced by UVB, and this mutant has application value in preventing UVB-induced skin photodamage response and preparing products for preventing UVB-induced skin photodamage.

Description

Technical Field

[0001] The present invention belongs to the fields of enzyme engineering and genetic engineering, and particularly relates to a truncated mutant of PERK protein and its application. Background Art

[0002] Solar radiation is an important environmental risk factor inducing human skin damage, and among them, ultraviolet (UV) radiation has the closest relationship with photo-damage effects. UV can be divided into ultraviolet A (UVA), ultraviolet B (UVB) and ultraviolet C (UVC), and their effects of inducing skin photo-damage responses increase in turn. However, since UVC can be filtered by the ozone layer, its injury effect reaching the earth's surface is weak. And the damage effect of UVB can be more than 1000 times that of UVA. Therefore, UVB is recognized as the most destructive component of solar radiation to the human body. Research shows that UVB can damage the structures and functions of proteins, lipids and nucleic acids, thereby triggering pathological damage responses such as skin burns, blisters, dermatitis and even skin cancer. Therefore, the research on prevention and control strategies, technologies and drugs for the photo-damage effect induced by UVB has always attracted much attention.

[0003] p53 is a nuclear transcription factor with tumor suppressor function. Our team revealed in previous studies that UVB can induce p53 activation, thereby up-regulating the expression of the apoptosis response-specific target gene PERP, and ultimately mediating the apoptosis effect of promoting skin keratinocytes and stromal cells. This result provides a clear guiding idea for the research on the strategy of targeting the p53-PERP pathway to antagonize the skin photo-damage response induced by UVB. Previous studies screened for p53-binding proteins and upstream protein kinases, and the results found that during the process of UVB inducing p53 activation and promoting apoptosis response, it can have an inducible binding reaction with the endoplasmic reticulum (ER) stress sensor protein PERK (protein kinase R-like ER kinase). The ER stress response mediated by PERK plays an important regulatory role in cell survival and apoptosis responses. Through research, it was found that PERK can bind to p53 under the stimulation of UVB and mediate its phosphorylation modification reaction and the activation reaction of the p53-PERP pathway.

[0004] However, due to the large size of the PERK protein, which has thousands of amino acids, it is not suitable for the preparation of drugs and pharmacological research. Therefore, there is an urgent need for its truncated mutants for subsequent functional studies. By designing truncated mutants, the functions of protein functional domains can be understood, which regions are essential structures can be determined, and the effects of such structures on the activity and stability of the entire protein can be judged, thus providing important evidence for the research on the structure and function of the protein. SUMMARY OF THE INVENTION

[0005] To make up for the deficiencies of the prior art, the purpose of the present invention is to provide a truncated mutant of the PERK protein and its application in preventing UVB-induced skin photo-damage.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] In the first aspect of the present invention, a truncated mutant of the PERK protein is provided, and the amino acid sequence of the truncated mutant is as shown in SEQ ID NO:1 in the sequence listing.

[0008] In the second aspect of the present invention, a coding nucleic acid, a vector containing the coding nucleic acid, or a recombinant host cell containing the coding nucleic acid or the vector is provided. The coding nucleic acid can encode the truncated mutant described in the first aspect of the present invention, and its nucleotide sequence is as shown in SEQ ID NO:2 in the sequence listing.

[0009] In the third aspect of the present invention, a primer is provided, which includes a forward primer and a reverse primer, and the primer can amplify the coding nucleic acid described in the second aspect of the present invention.

[0010] Furthermore, the nucleotide sequence of the forward primer is as shown in SEQ ID NO:3 in the sequence listing; the nucleotide sequence of the reverse primer is as shown in SEQ ID NO:4 in the sequence listing.

[0011] In the fourth aspect of the present invention, a derivative of the truncated mutant described in the first aspect of the present invention or the coding nucleic acid described in the second aspect of the present invention is provided.

[0012] Furthermore, the derivative is formed by the truncated mutant or the coding nucleic acid and other substances in the form of adsorption, encapsulation, or covalent binding.

[0013] Furthermore, the modification includes glycosylation, acylation, phosphorylation, acetylation, methylation, sulfation, or hydroxylation.

[0014] Furthermore, the other substances include one or more components selected from the group consisting of free adjuvants, stabilizers, buffers, surfactants, salts, and preservatives.

[0015] The fifth aspect of the present invention provides a pharmaceutical composition for preventing UVB-induced skin photo-damage, which comprises the truncated mutant described in the first aspect of the present invention; or the coding nucleic acid described in the second aspect of the present invention; or the derivative described in the fourth aspect of the present invention.

[0016] Furthermore, the pharmaceutical composition further comprises a pharmaceutically acceptable carrier.

[0017] The sixth aspect of the present invention provides a product for preventing UVB-induced skin photo-damage, which comprises the truncated mutant described in the first aspect of the present invention, the coding nucleic acid described in the second aspect of the present invention, the derivative described in the fourth aspect of the present invention, and / or the pharmaceutical composition described in the fifth aspect of the present invention.

[0018] The seventh aspect of the present invention provides the use of the truncated mutant described in the first aspect of the present invention, the coding nucleic acid described in the second aspect of the present invention, the derivative described in the fourth aspect of the present invention, and / or the pharmaceutical composition described in the fifth aspect of the present invention in the preparation of a product for preventing UVB-induced skin photo-damage.

[0019] The eighth aspect of the present invention provides a method for preparing the truncated mutant described in the first aspect of the present invention, and the method comprises genetic engineering techniques and artificial synthesis.

[0020] Furthermore, the genetic engineering technique refers to ligating the coding nucleic acid described in the second aspect of the present invention with a vector to obtain the recombinant vector described in the second aspect of the present invention, transforming the recombinant vector into a host cell to obtain the recombinant host cell described in the second aspect of the present invention, culturing, expressing and producing the truncated mutant described in the first aspect of the present invention with the recombinant host cell.

[0021] Advantages and beneficial effects of the present invention:

[0022] The present invention discovers that PERK can bind to p53 under the stimulation of UVB and mediate its phosphorylation modification reaction and the activation reaction of the p53-PERP pathway. And a PERK C-terminal mutant with the N-terminal removed is provided, which can antagonize the activation of the p53-PERP pathway induced by UVB and the pro-apoptotic effect, and this mutant has potential application value in the prevention and control of UVB-induced photo-damage reaction. Description of the drawings

[0023] Figure 1 It is a diagram showing the inducible binding reaction of PERK and p53 before and after UVB stimulates HaCaT cells for 12 hours. Figure 1 In which A is the immunoprecipitation reaction of the p53 antibody. Figure 1 In which B is the immunoprecipitation reaction of the PERK antibody. Figure 1C in it is the immunoprecipitation reaction of p53 antibody and PERK antibody in whole cell lysates;

[0024] Figure 2 It is a diagram showing the activation of the p53-PERP pathway and the apoptosis response induced by UVB in HaCaT cells mediated by PERK. Figure 2 A in it is the analysis of the induced activation of p53 and the change in the induced expression level of PERP after knocking down the expression level of PERK. Figure 2 B in it is the analysis of the apoptosis response after knocking down the expression level of PERK.

[0025] Figure 3 It is a diagram for the analysis of the structural basis of the inducible binding reaction between PERK and p53. Figure 3 A in it is the construction scheme of wild-type PERK and its truncated mutants. Figure 3 B in it is the analysis of the difference in the binding ability between wild-type PERK and its truncated mutants and p53.

[0026] Figure 4 It is a diagram for the analysis of the ability of PERK-M4 to regulate the activation of the p53-PERP pathway.

[0027] Figure 5 It is a diagram for the analysis of the ability of PERK-M4 to regulate the pro-apoptotic response induced by UVB. Detailed implementation manners

[0028] The present invention will be further described in detail below in conjunction with the specific implementation manners. The examples given are only for clarifying the present invention, rather than limiting the scope of the present invention. The following examples can be used as a guide for those of ordinary skill in the art to make further improvements, and do not constitute any limitation to the present invention in any way.

[0029] In the present invention, PERK includes the wild type, also known as EIF2AK3, PEK, WRS. This term encompasses the full-length, unprocessed PERK. This term encompasses, for example, the PERK gene, human PERK, and PERK from any other vertebrate source, including mammals such as primates and rodents (e.g., mice and rats). As a preferred embodiment, in the present invention, PERK is a human gene with the gene ID of 9451.

[0030] PERK-M includes mutant forms and fragments of PERK, and the term encompasses any form of PERK resulting from processing in a cell. The term encompasses naturally occurring variants of PERK (such as splice variants or allelic variants). The term encompasses, for example, mutant forms and fragments of human PERK, as well as mutant forms and fragments of PERK from any other vertebrate source, including mammals such as primates and rodents (e.g., mice and rats). As a preferred embodiment, in the present invention, PERK-M is the mutant constructed by the construction scheme in Example 2, including the truncated mutant PERK-M1 with 30-874 amino acids; the truncated mutant PERK-M2 with 30-669 amino acids; the truncated mutant PERK-M3 with 30-514 amino acids; the truncated mutant PERK-M4 with 514-1116 amino acids.

[0031] In the present invention, "coding nucleic acid" refers to any polymeric form of any length composed of ribonucleotides or deoxyribonucleotides. In the context of the present invention, it refers to a DNA sequence that, when placed under the control of appropriate regulatory sequences, is transcribed and translated into a polypeptide in a host cell. The boundaries of the coding nucleic acid sequence are determined by the start codon at the 5' (amino) end and the translation termination codon at the 3' (carboxyl) end. The coding sequence can include, but is not limited to, prokaryotic sequences, cDNA from eukaryotic mRNA, genomic DNA sequences from eukaryotic (e.g., mammalian) DNA, and even recombinant DNA sequences. The transcription termination sequence will generally be located at the 3' of the coding sequence. In a specific embodiment of the present invention, the coding nucleic acid refers to a nucleic acid sequence capable of encoding a truncated mutant of the PERK protein described in the first aspect of the present invention. Once the coding sequence of the truncated mutant described in the present invention is isolated, the truncated mutant can be obtained in large quantities using recombinant techniques.

[0032] In the present invention, a vector containing the coding nucleic acid described in the present invention is provided. The term "vector" refers to an artificial construct that is capable of delivering and preferably expressing one or more genes or sequences of interest in a host cell. The vector of the present invention can be a plasmid vector, a viral vector, etc. In some embodiments, the vector refers to a linear or circular nucleic acid molecule that contains the nucleic acid of the present invention operably linked to other segments providing for autonomous replication in a recombinant host cell, or an expression cassette according to the nucleic acid molecule. "Operably linked" means that the nucleic acid sequence of interest is linked to the regulatory sequence in a manner that permits the expression of the nucleotide sequence (e.g., in an in vitro transcription / translation system or when the vector is introduced into a host cell).

[0033] In the present invention, the term "recombinant host cell" refers to a host cell into which a vector has been introduced, enabling the recombinant host cell to transcribe the nucleic acid sequence of interest and / or translate the protein of interest. In the present invention, such genetic engineering techniques can be used to enable the recombinant host cell to express the truncated mutant described in the first aspect of the present invention. In one aspect of the present invention, the protein truncated mutants as claimed and described herein can be produced by recombinant techniques in mammalian host cells, such as, for example, CHO cells or other cell lines. Mammalian host cells and cell lines suitable for the recombinant production of a variety of different proteins are well known in the art.

[0034] In the present invention, the term "primer" refers to a macromolecule with a specific nucleotide sequence that stimulates synthesis at the initiation of nucleotide polymerization and is linked to the reactants by hydrogen bonds. Such a molecule is called a primer. Primers are usually two artificially synthesized oligonucleotide sequences. One primer is complementary to one DNA template strand at one end of the target region and is called the upstream primer; the other primer is complementary to the other DNA template strand at the other end of the target region and is called the downstream primer. Its function is to serve as the starting point for nucleotide polymerization, and the nucleic acid polymerase can start synthesizing a new nucleic acid strand from its 3' end.

[0035] In the present invention, the term "derivative" refers to a substance formed by the truncated mutant protein or coding nucleic acid described in the present invention in the form of modification, adsorption, encapsulation, or covalent binding with other substances, which retains the desired activity or characteristics of the protein or nucleic acid. In one embodiment of the present invention, the protein has co-translational and / or post-translational modifications, such as glycosylation, acylation, phosphorylation, acetylation, methylation, sulfation, or hydroxylation. These modifications can be obtained by production in mammalian cells or by site-directed modification of synthetic peptides in vitro. When the proteins of the present invention have amino acid substitutions relative to the relevant reference sequence, the substitutions are preferably conservative amino acid substitutions. The proteins of the present invention may also include modified amino acids. Amino acid modifications may include, for example, phosphorylation, acetylation, methylation, amidation, or any other amino acid modification known in the art, as long as the protein retains the desired characteristics.

[0036] In the present invention, the term "UVB" refers to ultraviolet B (Ultraviolet B), with a wavelength of 280 - 320 nm, which can promote mineral metabolism in the body and the formation of vitamin D, but can also cause skin tanning and cancer. Both the US Department of Health and Human Services and the World Health Organization have identified ultraviolet rays as proven human carcinogens. Ultraviolet radiation is considered the main cause of non-melanoma skin cancer (NMSC), including basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). And UVB is recognized as the most destructive component of solar radiation to the human body. UVB is the main cause of skin redness and sunburn, often damaging the more superficial surface layer of the skin. It plays a key role in the development of skin cancer and also plays an important role in tanning and photoaging. Research shows that UVB can damage the structure and function of proteins, lipids, and nucleic acids, thus triggering pathological damage reactions such as skin burns, blisters, dermatitis, and even skin cancer. Therefore, the research on prevention and control strategies, technologies, and drugs for the light damage effect caused by UVB has always attracted much attention.

[0037] In the present invention, the term "pharmaceutically acceptable carrier" refers to any pharmaceutical carrier that does not itself induce the production of antibodies harmful to the individual receiving the composition and can be administered without excessive toxicity. Suitable carriers can be large, slowly metabolized macromolecules such as proteins, polysaccharides, polylactic acid, polyglycolic acid, polymeric amino acids, and amino acid copolymers. Such carriers are well known to those of ordinary skill in the art. The pharmaceutically acceptable carrier in a pharmaceutical composition can include fluids such as water, saline, glycerol, and ethanol. Auxiliary substances such as protein stabilizers, wetting agents or emulsifiers, pH buffering substances, etc. can also be present in such media. In some embodiments, the truncated mutants, encoding nucleic acids, derivatives, and / or pharmaceutical compositions of the present invention can optionally be used in combination with one or more adjuvants, pharmaceutically acceptable carriers or excipients such as stabilizers, buffers, surfactants, salts, and / or preservatives.

[0038] The pharmaceutical composition of the present invention can also be used in combination with other drugs for preventing and treating UVB-induced light damage. Other compounds for preventing and treating UVB-induced light damage can be administered simultaneously with the main active ingredient (for example, the truncated mutant PERK-M4 of the PERK protein), or even simultaneously in the same composition. Other therapeutic compounds can also be administered separately in a separate composition or in a dosage form different from that of the main active ingredient. A partial dose of the main ingredient can be administered simultaneously with other compounds for preventing and treating UVB-induced light damage, while other doses can be administered separately.

[0039] In the present invention, "HaCaT cells" refer to immortalized human keratinocytes. This cell line is derived from the normal skin surrounding the lesion of a 62-year-old male with melanoma. It is an immortalized human keratinocyte naturally transformed after in vitro culture and is also the first immortalized epidermal cell line. HaCaT cells can be used to study the damaging effects of ultraviolet rays on human skin keratin.

[0040] In the present invention, the term "Immunoprecipitation (IP)" refers to a method of small-scale affinity purification of antigens using specific antibodies immobilized on solid-phase supports such as magnetic beads or agarose resins. Immunoprecipitation is one of the most commonly used methods when it is necessary to isolate proteins and other biomolecules from cell or tissue lysates for immunoblotting detection or other detection techniques. An antibody (monoclonal or polyclonal) specific to a particular protein is immobilized on an insoluble support (such as agarose or magnetic beads) and then incubated with a cell lysate containing the target protein. During incubation, the lysate is gently agitated to allow the target antigen to bind to the immobilized antibody, forming an antigen-antibody immune complex. Subsequently, the immune complex is eluted from the solid-phase support for analysis of the properties of the target antigen. Free unbound antibodies can also be added to the lysate to form immune complexes, and then the complexes are recovered using a filler. Although the pre-immobilized antibody method is more commonly used for IP, if the concentration of the target protein is low and the binding affinity between the antibody and the antigen is weak, the method of forming immune complexes using free antibodies is better.

[0041] In the present invention, the term "siRNA" refers to small interfering RNA, which can regulate gene expression through a phenomenon called RNA interference (RNAi). siRNA can be used as a tool to study the functions of single genes in vivo and in vitro and is an attractive new class of therapies, especially for treating undruggable targets in cancer and other diseases. siRNA delivery systems are divided into non-viral delivery systems and viral delivery systems. Non-viral delivery systems include polymers, lipids, peptides, etc., which are widely studied siRNA delivery systems. The effective pharmacological use of siRNA requires a "vector" that can deliver siRNA to its intended site of action. The vector assembles siRNA into a supramolecular complex, which exhibits functional characteristics during delivery.

[0042] In the present invention, the term "WESTERN - BLOT" refers to protein immunoblotting, which uses polyacrylamide gel electrophoresis (SDS - PAGE). The analyte is protein, the "probe" is an antibody, and "color development" is carried out with labeled secondary antibody. SDS - PAGE can separate protein samples and transfer them to a solid support (such as nitrocellulose membrane). The solid support can adsorb proteins and keep the polypeptide types and their biological activities separated by electrophoresis unchanged.

[0043] In the present invention, the term "trypan blue exclusion assay" is also known as "trypan blue dye exclusion method", which is a rapid and simple method for detecting cell viability by the method that trypan blue can only stain dead cells blue while live cells cannot be stained. Its principle is that normal cells have a complete cell membrane structure, while the cell membrane structure of dead cells is damaged. Trypan blue cannot pass through the normal cell membrane, so normal cells are not stained by trypan blue, while dead cells can be stained blue by trypan blue.

[0044] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The following embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. Simple improvements made to the present invention according to its essence all fall within the scope claimed by the present invention. It should be noted that the experimental methods in the following embodiments are all conventional methods unless otherwise specified, and the materials and reagents used in the following embodiments are all obtained from commercial sources unless otherwise specified.

[0045] Example 1 Verification of the binding ability between PERK protein and p53

[0046] 1. Establish a UVB - induced skin photo - damage model:

[0047] Using human skin keratinocytes (HaCaT) as a model, irradiate the cells with the UVB dose (0.5 kJ / m2) that has been proven to induce apoptosis in HaCaT cells in previous studies, and detect the relevant protein expression levels and analyze the apoptosis response at designated time periods after irradiation.

[0048] 2. Verification of the binding ability between PERK protein and p53:

[0049] 1) Harvest HaCaT cells before and 12 hours after UVB stimulation. After lysis, take 500 mg of whole - cell lysate for immunoprecipitation reaction with anti - p53 antibody, and identify the immunoprecipitate with anti - PERK antibody. The results are as shown in Figure 1 A in it.

[0050] 2) After obtaining the experimental results of the inducible binding of p53 to PERK under UVB stimulation, a reverse immunoprecipitation method was used for verification, that is, the whole cell extract was subjected to immunoprecipitation reaction with an anti-PERK antibody, and the immunoprecipitate was identified with an anti-p53 antibody. The results are as Figure 1 shown in B of

[0051] 3) In steps 1) and 2), the total protein expression levels of p53 and PERK and their phosphorylation-induced activation levels in the whole cell lysate were synchronously detected. The results are as Figure 1 shown in C of

[0052] The above results indicate that the PERK protein can inducibly bind to p53 after UVB stimulation.

[0053] 3. Knockdown of the PERK protein to verify its role in the p53-PERP pathway and apoptosis response

[0054] 1) Transfect PERK siRNA into HaCaT cells.

[0055] 2) Under the condition that the PERK expression level was knocked down, the changes in the phosphorylation modification level of p53 and the expression level of PERP were detected by the WESTERN-BLOT method. The results are as Figure 2 shown in A of

[0056] 3) The change in the apoptosis ratio was detected by the trypan blue exclusion experiment. The results are as Figure 2 shown in B of

[0057] The above results indicate that the PERK protein is a novel upstream protein kinase that mediates the activation of p53 induced by UVB.

[0058] Example 2 Construction of PERK mutants and analysis of differences in their p53 binding ability

[0059] 1. Construction scheme of PERK truncated mutants

[0060] 1) A series of PERK truncated mutants were constructed according to the structural and functional domain characteristics of the PERK protein. The full-length PERK is 30 - 1116 amino acids; the truncated mutant PERK-M1 is 30 - 874 amino acids; the truncated mutant PERK-M2 is 30 - 669 amino acids; the truncated mutant PERK-M3 is 30 - 514 amino acids; the truncated mutant PERK-M4 is 514 - 1116 amino acids, as Figure 3 shown in A of

[0061] The primers for constructing the full-length and each PERK mutant are as follows:

[0062] Table 1. Primer sequence list of full-length and truncated mutants of PERK

[0063]

[0064] 2) Each of the above primer pairs was used to amplify the cDNA of each PERK mutant, which was respectively inserted into the pcDNA3.1-FLAG empty vector to construct each expression plasmid.

[0065] 3) The expression plasmids of full-length and truncated PERK mutants were co-expressed with the HA-p53 expression plasmid in HaCaT cells. Whole cell lysates were taken and immunoprecipitated with an anti-p53 antibody, and the immunoprecipitates were identified with an anti-FLAG antibody; PERK mutants that lost the ability to bind p53 were screened, and the results are shown as Figure 3 shown in B of

[0066] The above results indicate that the N-terminus of PERK mediates its binding reaction with p53. Therefore, the C-terminal mutant of PERK (PERK-M4) completely loses the p53 binding reactivity.

[0067] Example 3 Analysis of the apoptotic response of PERK-M4 mutant to UVB-treated HaCaT cells

[0068] 1. Full-length PERK and PERK mutants that lost the ability to bind p53 were reconstituted in HaCaT cells with knocked-down PERK expression levels. The ability differences of wild-type and mutant PERK in mediating the activation reaction of the UVB-induced p53-PERP pathway before and after UVB irradiation were detected by the WESTERN-BLOT method. The results are shown as Figure 4 shown. Compared with wild-type PERK, PERK-M4 lost the functions of activating p53 and inducing PERP expression.

[0069] 2. The ability differences of wild-type and mutant PERK in mediating the UVB-induced cell apoptosis reaction before and after UVB irradiation were detected by the trypan blue exclusion experiment. The results are shown as Figure 5 shown. PERK-M4 can antagonize the UVB-induced pro-apoptotic reaction.

[0070] The above results indicate that the C-terminal truncated mutant of PERK, PERK-M4, has the function of targeting p53 and antagonizing the UVB-induced pro-apoptosis of skin keratinocytes. The amino acid sequence, nucleotide sequence of PERK-M4 and the sequences of the amplification primers of full-length and each mutant in the present invention are shown in Table 2.

[0071] Table 2. PERK-related sequence list

[0072]

[0073]

[0074]

[0075]

[0076] The present invention has been described in detail above. For those skilled in the art, without departing from the gist and scope of the present invention and without unnecessary experiments, the present invention can be implemented within a relatively wide range under equivalent parameters, concentrations, and conditions. Although embodiments of the present invention are given, it should be understood that the present invention can be further improved. In short, according to the principle of the present invention, this application intends to cover any modifications, uses, or improvements to the present invention, including those that depart from the scope disclosed in this application but are made by using conventional techniques known in the art.

Claims

1. A truncated mutant of PERK protein, characterized in that, The amino acid sequence of the truncated mutant is shown as SEQ ID NO:1 in the sequence listing.

2. A nucleic acid, characterized in that, The nucleic acid encodes the truncated mutant according to claim 1, and its nucleotide sequence is shown as SEQ ID NO:2 in the sequence listing.

3. A pharmaceutical composition for preventing UVB-induced skin photo-damage, characterized in that, The pharmaceutical composition comprises the truncated mutant according to claim 1; or comprises the nucleic acid according to claim 2.

4. The pharmaceutical composition according to claim 3, wherein The pharmaceutical composition further comprises a pharmaceutically acceptable carrier or excipient, and the excipient is selected from stabilizers, buffers, surfactants, salts and / or preservatives.

5. Use of the truncated mutant according to claim 1 and / or the nucleic acid according to claim 2 in the preparation of a medicament for preventing UVB-induced skin photodamage.

6. A method for preparing the truncated mutant according to claim 1, characterized in that, The method includes genetic engineering techniques and artificial synthesis.

7. The method according to claim 6, characterized in that The genetic engineering technique refers to ligating the nucleic acid according to claim 2 with a vector to obtain a recombinant vector, transforming the recombinant vector into a host cell to obtain a recombinant host cell, and culturing, expressing and producing the truncated mutant according to claim 1 from the recombinant host cell.

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