Construction and application of a group of spontaneously mutant Hr gene-introduced inbred mouse models

Abstract

The present invention provides a method for constructing an inbred mouse model by introducing a group of spontaneously mutated Hr genes and its application. The method is to introduce the target gene into the inbred strain by homologous introduction to obtain a new gene introduction animal model. First, the ICR-Hr from the outbred group with strong genetic polymorphism is introduced. hr (Trade name: SHJH hr ) were introduced into the inbred BALB / cAShjh mice to establish the BALB / cA.Cg.ICR‑Hr hr / Shjh mice, and then continued to be introduced into the inbred C57BL / 6JShjh mice to establish C57BL / 6J.Cg.BALB / cA-Hr hr / Shjh, thereby establishing a homologous introduction inbred line, each introduction needs to be repeated for 10 or more consecutive generations, and repeated backcrossing allows the recipient strain to replace the chromosomes of the donor strain with the chromosomes other than the chromosome region carrying the Hr allele, so that related applications can continue to be studied on the characteristics of each strain.

Description

Technical Field

[0001] The present invention belongs to the technical field of hairless mouse models, and in particular relates to a method for constructing an inbred mouse model by introducing a group of spontaneously mutated Hr genes and its application. Background Art

[0002] The hairless mouse is a new strain of mice resulting from a mutation in the hairless gene. These mice have normal fur at birth, which begins to gradually shed from head to tail around 14 days old, and completely shed within 1 week to 10 days, remaining hairless for life. These mice exhibit a range of changes, including a normal thymus gland, premature skin aging, slowed movement, significantly shortened lifespan, and reproductive dysfunction. The gene also affects changes in bone cells, the thyroid gland, and telomerase enzyme levels. Given the characteristic changes in hairless mice, studying their mechanisms and their relationship to human disease is of great significance.

[0003] There are many mature strains of hairless mice abroad, such as Hairless mice, Rhinomice, hr rh There are numerous hairless mice, including the BALB / C hairless mouse, the flakyskin mouse, the Nackt mouse, and the HRS / J mouse. Currently, hairless mice developed in China include the Yuyi hairless mouse. However, most of these mice were discovered and reported in populations of mice with outbred backgrounds. The most recent report discovered the hr / hr gene in an ICR mouse population and bred it to establish a stable, genetically defined experimental animal population. Further research has shown that the hr / hr gene is an allele of the Hr gene, and that the hairless mutant gene (hr) is located on chromosome 14 and is inherited in an autosomal recessive manner. In 1989, Cachón-González et al. cloned the hairless gene (hr) and hypothesized that it is a transcription factor that is positively regulated by thyroid hormone and is expressed prominently only in hair follicles in the brain and skin. Other studies have experimentally introduced the target gene into strains with defined genetic backgrounds, and subsequently used genetic testing and phenotypic selection criteria to develop new genetic strains. The existing allelic mutations in the hairless (Hr) gene constitute a group of mouse models that cause hair loss through partial or complete loss of Hr function in various mammals, providing a rich resource for the study of skin diseases, aging, hair follicle biology, etc.

[0004] Spontaneous mutation Hairless Shjh:ICR-Hr hr (SHJH hrIn the development of hairless mice, this mutant mouse model is stable and can form a strain. However, the background strain is an outbred ICR mouse, which is characterized by high genetic polymorphism, which has certain limitations in genetic screening and research. Furthermore, the experimental methods for introducing the target gene require high technical requirements, and laboratory methods cannot fully simulate the normal conditions of the animal. The transferred gene needs to be continuously tested during subsequent breeding, and it is easy to be lost or mutated during the breeding process. Therefore, it is necessary to obtain a stable and heritable hairless mutant mouse model through other means. Summary of the Invention

[0005] In order to address the shortcomings of the prior art, the present invention aims to provide a method for constructing a set of spontaneously mutated hr gene-introduced inbred mouse models and their applications. The method involves introducing the target gene into an inbred strain by homologous introduction to obtain a new gene-introduced animal model. First, the inbred strain BALB / cAShjh mice are introduced to establish BALB / cA.Cg.ICR-Hr hr / Shjh mice, which were then introduced into inbred C57BL / 6JShjh mice to establish C57BL / 6J.Cg.BALB / cA-Hr hr / Shjh, thereby establishing a homologous introduction inbred line, each introduction needs to be repeated for 10 or more consecutive generations, and repeated backcrossing allows the recipient strain to replace the chromosomes of the donor strain with the chromosomes other than the chromosome region carrying the hr mutant gene, so that related applications can continue to be studied based on the characteristics of each strain.

[0006] One of the objectives of the present invention is to provide a method for constructing a group of spontaneously mutated hr genes into an inbred mouse model, characterized in that the method comprises the following steps:

[0007] 1) Shjh:ICR-Hr hr (Trade name SHJH hr Homozygous recessive male BALB / cAShjh mice and inbred female BALB / cAShjh mice were raised to over 8 weeks of age and mated (hr / hr♂×+ / +♀). All the resulting offspring were F1 heterozygotes (+ / hr), all had white fur, and the BALB / cAShjh gene was introduced into 50% of the offspring.

[0008] 2) Heterozygous male and heterozygous female mice from step 1) were raised to 8 weeks of age and interbred (+ / hr♂ × + / hr♀). Homozygous and heterozygous offspring were generated. Recessive homozygous (hr / hr) mice, i.e., 25% were hairless, accounting for 25%; dominant homozygous (+ / +) mice, accounting for 25%; and heterozygous (+ / hr) mice, accounting for 50%; these mice were hairy, conforming to Mendel's law of inheritance. Recessive homozygous (hr / hr) male mice were selected and labeled N1.

[0009] 3) N1 was raised with female BALB / cAShjh mice until they were 8 weeks old and mated to produce the F1 offspring, all of which were heterozygous (+ / hr);

[0010] 4) Raise the F1 offspring from step 3) to 8 weeks of age and perform reciprocal crosses (+ / hr♂ × + / hr♀). The offspring will contain homozygous and heterozygous offspring in the same ratio as in step 2). Select recessive homozygous male mice (hr / hr) and label them as N2.

[0011] 5) Repeat steps 3)-4) for 10 generations or more. At this point, except for the selected Hr allele, the offspring genome is mostly identical to the recipient genome and is named BALB / cA.Cg.ICR-Hr hr / Shjh, referred to as BALB / cA-Hr hr / Shjh.

[0012] Preferably, by the N10 generation, the progeny genome is largely identical (99.81%) to the recipient genome except for the selected mutant allele Hr.

[0013] Another object of the present invention is to provide a mouse model BALB / cA.Cg.ICR-Hr constructed by the above method hr / Shjh.

[0014] Another object of the present invention is to provide a gene-transferred inbred mouse model C57BL / 6J.Cg.BALB / cA-Hr hr / Shjh construction method, characterized in that the method comprises the following steps:

[0015] 1) The above BALB / cA-Hr hr Homozygous recessive male / Shjh mice and inbred C57BL / 6JShjh female mice were raised to over 8 weeks of age and mated (hr / hr♂×+ / +♀). All the resulting offspring were F1 heterozygotes (+ / hr), and all animals had a wild mouse appearance.

[0016] 2) Heterozygous (+ / hr) male and heterozygous (+ / hr) female mice from step 1) were raised to at least 8 weeks of age and interbred (+ / hr♂ × + / hr♀). The offspring showed coat color differentiation, and homozygous and heterozygous mice were distinguished, with coat colors ranging from light to dark (white, light brown, brown, hamster, black, etc.). Recessive homozygous mice experienced hair loss after two weeks, accounting for 25%, consistent with Mendel's law of inheritance. Recessive homozygous male mice with darker coat colors (hamster or black) were selected and entered into step 3).

[0017] 3) The recessive homozygous male mice (hr / hr) selected in step 2) were raised with female C57BL / 6JShjh mice (+ / +) until they were over 8 weeks old and mated (hr / hr♂×+ / +♀). The resulting offspring were the F1 hybrid generation (+ / hr). At this time, the coat color also showed a phenomenon of varying shades, with a decrease in light colors and an increase in dark colors. All offspring were heterozygous;

[0018] 4) Select darker colored (wild mouse or black) F1 offspring (+ / hr) from step 3) above, raise them to 8 weeks, and then intercross (+ / hr♂ × + / hr♀). The offspring will show coat color differentiation and homozygous and heterozygous offspring will appear. Following the selection principles of step 2), select male recessive homozygous mice (hr / hr) that meet the requirements;

[0019] 5) Repeat steps 3) and 4), wherein starting from the fourth generation, the coat color differentiation decreases, the black color increases, and the probability of white color appears almost zero. After 10 generations or more of breeding, at this time, except for the selected mutant allele Hr, the majority (99.81%) of the offspring genome is identical to the recipient genome and is named C57BL / 6J.Cg.BALB / cA-Hr hr / Shjh mice.

[0020] Preferably, by the N10 generation, the progeny genome is largely identical (99.81%) to the recipient genome except for the selected mutant allele Hr.

[0021] Another object of the present invention is to provide a mouse model C57BL / 6J.Cg.BALB / cA-Hr constructed by the above method hr / Shjh.

[0022] Further preferably, the mouse model is used in the fields of dry skin model, external moisturizer testing, skin infection model, external disinfectant effect verification, dermatitis and skin aging, muscle aging, joint aging, osteoporosis model, etc.

[0023] Further preferably, the mouse model is used in the preparation of products for studying the molecular mechanisms of a series of abnormal phenotypes caused by mutations and for promoting the model.

[0024] Beneficial technical effects of the present invention:

[0025] 1. This study used the NX system breeding protocol to breed hairless mice found in the outbred ICR mice. The mice were then backcrossed and selfed with the inbred BALB / cAShjh mice for 10 generations. In each generation, only those offspring that acquired the donor allele at the differential loci were selected for the next round of backcrossing. According to Mendel's law of genetic segregation, 50% of the gene loci in these backcross hybrid offspring animals randomly carry the recipient allele, and the remaining 50% randomly carry the donor allele. Therefore, the heterozygosity level decreases by approximately 50% in each generation. According to Snall (1978)'s formula [1-(1 / 2) N-1 ], in the N5 generation, after only four backcross-intercrosses, about 94% of the genome of its progeny was identical to the recipient inbred line. By the N10 generation, the genomic identity had increased to 99.81%.

[0026] 2. In order to verify the genetic characteristics of the inbred strain after the mutant gene was introduced, the single nucleotide polymorphism (SNP) site method was used to select 90 SNP sites from the SNP public database. These sites are distributed on each autosome and sex chromosome. The results showed that except for the two sites rs13484115 and rs13484116, the genotypes of other sites were the same as those of BALB / cAShjh mice. At the same time, the biochemical marker detection method was used to detect the 14 biochemical site marker genes of the mouse, and the results further verified the BALB / cA.Cg.ICR-Hr hr / Shjh(hereinafter referred to as BALB / cA-Hr hr / Shjh) mice and were completely identical to the recipient BALB / cAShjh mice.

[0027] 3. Whole exome sequencing is a widely used next-generation sequencing (NGS) method that involves sequencing the protein-coding regions of the genome. hrWhole-genome exome analysis of BALB / cAShjh mice revealed a total of 109 mutations. Compared to the recipient BALB / cAShjh mice, 20 genes were screened for missense / nonsense mutations. These mutations, due to changes in the amino acids they encode, may alter gene function. In addition to the hr gene, which has been reported to directly affect hair growth and rhinoceros-like skin lesions, several genes, such as Akap11, Diaph3, and Pibf1, are functionally implicated. The disease phenotypes of the mutant mice correlated with previously measured physiological and biochemical data. Furthermore, a number of the mutant genes were implicated in downstream signaling pathways, and simulations revealed a significant number of deleterious mutations, suggesting transcriptome differences between the mutant and normal mice.

[0028] 4. The results also showed that the donor SHJH hr Same as mice, BALB / cA-Hr hr Shjh mice lose their hair starting at the nose tip after about 12 to 14 days and then spread all over the body. Except for the vibrissae, all hair on the body is completely shed by 30 to 35 days. This is a common feature of all Hr allele mutations. However, as they age, the nails of these mice increase in length rapidly. At about 6 months of age, the nails grow excessively. After 10 months of age, the nails are of different lengths and curl in disorder. This is consistent with SHJH. hr Mice are different ( Figure 5 ), but the phenotype is exactly the same as that described by Liu (2010). BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 . The gene of the present invention is introduced into the inbred mouse model BALB / cA.Cg.ICR-Hr hr / Flowchart of Shjh's construction method;

[0030] Figure 2 .Inbreeding coefficient of N1-N10 generations of mice;

[0031] Figure 3 Three SNPs obtained by HR gene sequencing;

[0032] Figure 4 .BALB / cA.Cg.ICR-Hr hr Differentiated SNPs in exon segments between BALB / cAShjh mice and BALB / cAShjh mice (partial)

[0033] Figure 5 .BALB / cA.Cg.ICR-Hr hr Nail growth of / Shjh mice at different ages. DETAILED DESCRIPTION

[0034] Example 1

[0035] A method for constructing a model of an inbred mouse strain by introducing a group of spontaneously mutated Hr genes, characterized in that the method comprises the following steps:

[0036] 1) Shjh:ICR-Hr hr (Trade name SHJH hr Homozygous recessive male BALB / cAShjh mice and inbred female BALB / cAShjh mice were raised to over 8 weeks of age and mated (hr / hr♂×+ / +♀). All the resulting offspring were F1 heterozygotes (+ / hr), all had white fur, and the BALB / cAShjh gene was introduced into 50% of the offspring.

[0037] 2) Heterozygous male and heterozygous female mice from step 1) were raised to 8 weeks of age and interbred (+ / hr♂ × + / hr♀). Homozygous and heterozygous offspring were generated. Recessive homozygous (hr / hr) mice, i.e., 25% were hairless, accounting for 25%; dominant homozygous (+ / +) mice, accounting for 25%; and heterozygous (+ / hr) mice, accounting for 50%; these mice were hairy, conforming to Mendel's law of inheritance. Recessive homozygous (hr / hr) male mice were selected and labeled N1.

[0038] 3) N1 was raised with female BALB / cAShjh mice until they were 8 weeks old and mated to produce the F1 offspring, all of which were heterozygous (+ / hr);

[0039] 4) Raise the F1 offspring from step 3) to 8 weeks of age and perform reciprocal crosses (+ / hr♂ × + / hr♀). The offspring will contain homozygous and heterozygous offspring in the same ratio as in step 2). Select recessive homozygous male mice (hr / hr) and label them as N2.

[0040] 5) Repeat steps 3)-4) for 10 generations or more. At this point, except for the selected mutant Hr allele, the offspring genome is mostly identical to the recipient genome and is named BALB / cA.Cg.ICR-Hr hr / Shjh, referred to as BALB / cA-Hr hr / Shjh. .

[0041] Example 2

[0042] A gene-introduced inbred mouse model C57BL / 6J.Cg.BALB / cA-Hr hr / Shjh construction method, characterized in that the method comprises the following steps:

[0043] 1) The BALB / cA-Hr obtained in Example 1 was hrMale homozygous / Shjh recessive mice and female inbred C57BL / 6JShjh mice were raised to over 8 weeks of age and mated (hr / hr♂×+ / +♀). All the resulting offspring were F1 heterozygotes (+ / hr), and all animals had a wild mouse appearance.

[0044] 2) Heterozygous (+ / hr) male and heterozygous (+ / hr) female mice from step 1) were raised to at least 8 weeks of age and interbred (+ / hr♂ × + / hr♀). The offspring showed coat color differentiation, and homozygous and heterozygous mice were distinguished, with coat colors ranging from light to dark (white, light brown, brown, hamster, black, etc.). Recessive homozygous mice experienced hair loss after two weeks, accounting for 25%, consistent with Mendel's law of inheritance. Recessive homozygous male mice with darker coat colors (hamster or black) were selected and entered into step 3).

[0045] 3) The recessive homozygous male mice (hr / hr) selected in step 2) were raised with female C57BL / 6JShjh mice (+ / +) until they were over 8 weeks old and mated (hr / hr♂×+ / +♀). The resulting offspring were the F1 hybrid generation (+ / hr). At this time, the coat color also showed a phenomenon of varying shades, with a decrease in light colors and an increase in dark colors. All offspring were heterozygous;

[0046] 4) Select darker colored (wild mouse or black) F1 offspring (+ / hr) from step 3) above, raise them to 8 weeks, and then intercross (+ / hr♂ × + / hr♀). The offspring will show coat color differentiation and homozygous and heterozygous offspring will appear. Following the selection principles of step 2), select male recessive homozygous mice (hr / hr) that meet the requirements;

[0047] 5) Repeat steps 3) and 4), wherein starting from the fourth generation, the coat color differentiation decreases, the black color increases, and the probability of white color appears almost zero. After 10 generations or more of breeding, at this time, except for the selected mutant allele Hr, the majority (99.81%) of the offspring genome is identical to the recipient genome and is named C57BL / 6J.Cg.BALB / cA-Hr hr / Shjh mice.

[0048] Example 3

[0049] BALB / cA-Hr hr / Shjh mouse model gene purity and consistency analysis with recipient mice, characterized in that the analysis method comprises the following steps:

[0050] 1) Genotyping of 90 SNPs was performed and compared with the BALB / cAShjh strain to test the genetic purity and consistency of the new strain with the recipient mice;

[0051] 2) According to the method of GB / T14927.1-2008 "Biochemical marker detection method for inbred mice and rats in laboratory animals", 14 biochemical locus marker genes were tested for consistency with the recipient mice.

[0052] Example 4

[0053] C57BL / 6J.Cg.BALB / cA-Hr hr / Shjh mouse model gene purity and consistency analysis with recipient mice, characterized in that the analysis method comprises the following steps:

[0054] 1) Genotyping of 90 SNPs was performed and compared with the C57BL / 6JShjh strain to test the genetic purity and consistency of the new strain with the recipient mice;

[0055] 2) According to the method of GB / T14927.1-2008 "Biochemical marker detection method for inbred mice and rats in laboratory animals", 14 biochemical locus marker genes were tested for consistency with the recipient mice.

[0056] The results are as follows: The technical principle of the present invention is based on SHJH hr The hybrid offspring of mice and BALB / cAShjh mice are indistinguishable. Taking advantage of the special phenotype of the mutant allele Hr when homozygous (hair loss → hairless), a backcross-selfing breeding program ( Figure 1 ) so that the variant allele produces homozygotes in the alternating generations (hr / hr). According to the calculation formula of the inbreeding coefficient of Snell (1978) (F = [1-(1 / 2) N-1 ]), when the backcross-intercross reaches the tenth generation, except for the selected mutant allele, the genome of the offspring is mostly the same as that of the recipient ( Figure 2 The inbreeding coefficient of the N10 generation mice is: F = [1-(1 / 2) N-1 ]=[1-(1 / 2) 10-1 ]=99.81%.

[0057] The BALB / cA-Hr hr / Shjh strains were tested for whole genome exons, and a total of 109 mutation sites were detected, involving 32 genes. Bioinformatics analysis found that these mutations were concentrated on chromosome 14, from 70547013 to 99302109. Among them, there were 71 synonymous mutations and 37 missense mutations. Among them, SNPs that caused changes in protein amino acid sequences involved 20 genes (Table 1), and 1 stop codon was added (stopgain). It was found that the gene related to hair loss was the Hr gene, with a total of 3 mutations, namely a synonymous mutation (70558252C>T), a missense mutation (70559773T>A) and a nonsense mutation (70559644C>T) ( Figure 3 、 Figure 4 ).

[0058] Table 1. BALB / cA.Cg.ICR-Hr hr Mutation sites and harmfulness prediction in exon regions of / Shjh mice

[0059]

[0060] The SNP detection site genotype results showed that the BALB / cA-Hr hr The genotyping of SHJH mice showed no heterozygotes. Among the 90 SNP sites tested, except for rs13484115 (A→G) and rs13484116 (T→G), the genotypes of other sites were the same as those of BALB / cAShjh mice (Table 2). hr The Hr gene has been introduced into the recipient BALB / cAShjh mice, and the inbred strain BALB / cA.Cg.ICR-Hr hr / Shjh mice.

[0061] Table 2. BALB / cA.Cg.ICR-Hr hr Differences in SNP markers between / Shjh mice and BALB / cAShjh mice

[0062] <![CDATA[BALB / cA.Cg.ICR-Hr hr / Shjh]]> BALB / cAShjh <![CDATA[BALB / cA.Cg.ICR-Hr hr / Shjh]]> 0 / 90 2*90 BALB / cAShjh 2*90 0 / 90

[0063] *SNP sites: rs13484115 (A→G), rs13484116 (T→G)

[0064] To further verify the N10 generation BALB / cA.Cg.ICR-Hr hrThe main genome of the / Shjh mice was derived from the BALB / cAShjh mice. The biochemical marker gene detection was performed on the N10 generation offspring. The results showed (Table 3) that the 14 biochemical marker genes detected were exactly the same as those of the inbred BALB / cA mice.

[0065] Table 3. BALB / cA.Cg.ICR-Hr hr Differences in biochemical marker genes between BALB / cAShjh mice and BALB / cAShjh mice

[0066]

[0067] The above description is only a preferred embodiment of the present invention. Without departing from the principles of the present invention, all technical solutions formed by equivalent replacement or equivalent transformation fall within the scope of protection required by the present invention.

Claims

1. A gene-transferred inbred mouse model C57BL / 6J.Cg.BALB / cA-Hr hr / Shjh construction method, characterized in that, The method comprises the following steps: 1) Shjh:ICR-Hr hr , whose trade name is SHJH hr Homozygous recessive male mice and inbred BALB / cAShjh female mice were raised to over 8 weeks of age and mated to reproduce. All the resulting offspring were F1 heterozygotes with white fur and BALB / cAShjh gene introduction rate reaching 50%. 2) Heterozygous male and heterozygous female mice from step 1) were raised to 8 weeks of age and interbred, with a ratio of + / hr♂ × + / hr♀. Homozygous and heterozygous offspring were generated, with 25% being recessive homozygous hr / hr mice, i.e., having a hairless phenotype; 25% being dominant homozygous + / + mice, having hair; and 50% being heterozygous + / hr mice, having hair. This conforms to Mendel's law of inheritance, and recessive homozygous hr / hr male mice were selected and labeled N1. 3) N1 was raised with female BALB / cAShjh mice until they were 8 weeks old and mated to produce the F1 offspring, all of which were heterozygous + / hr; 4) The F1 generation from step 3) was raised to 8 weeks old and intercrossed, with a ratio of + / hr♂ × + / hr♀. Homozygous and heterozygous offspring were generated, with 25% being recessive homozygous hr / hr mice, i.e., having a hairless phenotype; 25% being dominant homozygous + / + mice, having a hairy phenotype; and 50% being heterozygous + / hr mice, having a hairy phenotype. In accordance with Mendel's law of inheritance, male homozygous recessive hr / hr mice were selected and labeled N2. 5) Repeat steps 3)-4) for 10 generations or more. At this point, except for the selected mutant Hr allele, the offspring genome is mostly identical to the recipient genome and is named BALB / cA.Cg.ICR-Hr hr / Shjh, referred to as BALB / cA-Hr hr / Shjh; Among them, by the N10 generation, 99.81% of the offspring genome was identical to the recipient mouse BALB / cAShjh; 6) BALB / cA-Hr hr Male homozygous / Shjh recessive mice and female inbred C57BL / 6JShjh mice were raised to over 8 weeks of age and mated to reproduce, hr / hr♂×+ / +♀. All the resulting offspring were F1 heterozygous + / hr, and all animals had a wild mouse appearance; 7) Heterozygous + / hr male and heterozygous + / hr female mice from step 6) were raised to at least 8 weeks of age and interbred (+ / hr♂ × + / hr♀). The offspring showed coat color differentiation, as well as differentiation between homozygotes and heterozygotes. The coat colors ranged from light to dark, in the order of white, light brown, brown, hamster, and black. Recessive homozygous mice experienced hair loss after two weeks, accounting for 25%, consistent with Mendel's law of inheritance. Recessive homozygous male mice with darker hamster or black coats were selected for step 3). 8) The recessive homozygous male hr / hr mice selected in step 7) were raised with C57BL / 6JShjh+ / + female mice until they were at least 8 weeks old and mated to produce hr / hr♂×+ / +♀. The resulting offspring were the F1+ / hr hybrids. At this point, the coat color also showed varying shades, with a decrease in light colors and an increase in dark colors. All offspring were heterozygous. 9) Select the darker colored F1 offspring from step 8) (e.g., wild mouse or black), raise them to 8 weeks of age, and then intercross them (e.g., + / hr♂×+ / hr♀). The offspring will show coat color differentiation, as well as homozygous and heterozygous offspring. Following the selection principles from step 7), select male homozygous recessive male mice that meet the requirements. 10) Repeat steps 8) and 9), wherein starting from the 4th generation, the coat color differentiation decreases, the black color increases, and the probability of white color appears almost zero. After 10 generations or more of breeding, at this time, except for the selected mutant allele Hr, the offspring genome is 99.81% identical to the recipient genome, and is named C57BL / 6J.Cg.BALB / cA-Hr hr / Shjh mice.

2. A mouse model C57BL / 6J.Cg.BALB / cA-Hr constructed by the method of claim 1 hr / Shjh is used in the preparation of dry skin models, topical moisturizer testing models, skin infection models, topical disinfectant effect verification models, dermatitis and skin aging models, muscle aging models, joint aging models, and osteoporosis models.

3. A mouse model C57BL / 6J.Cg.BALB / cA-Hr constructed by the method of claim 1 hr / Shjh is used in the preparation of products for studying the molecular mechanisms and models of a series of abnormal phenotypes caused by mutations.

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