Col7a1 KO Mice

Catalog Number: C001539

Strain Name: C57BL/6JCya-Col7a1^em3/Cya

Genetic Background: C57BL/6JCya

Reproduction: Heterozygote x WT

Strain Description

Epidermolysis Bullosa (EB) is a genetic skin disease characterized by the formation of blisters and bullae on the skin and mucous membranes following minor trauma or friction. Common clinical symptoms include the appearance of blisters, blood blisters, and erosion on the skin. Depending on the site of onset, hereditary EB can be divided into three types: Simplex Epidermolysis Bullosa (EBS), Junctional Epidermolysis Bullosa (JEB), and Dystrophic Epidermolysis Bullosa (DEB). Mutations in the COL7A1 gene are the cause of Dystrophic Epidermolysis Bullosa (DEB), and the different clinical phenotypes presented by DEB are related to the mutation site and form of the COL7A1 gene. The COL7A1 gene encodes type VII collagen protein, which forms anchoring fibrils that bind the dermal tissue to the epidermal tissue. Functional deficiency of anchoring fibrils caused by COL7A1 mutations makes the patient's skin extremely fragile, easily causing blisters or tears due to minor friction or trauma. To date, at least 324 pathogenic mutations related to DEB have been found in the COL7A1 gene, including nonsense, missense, deletion, insertion, splicing, and regulatory mutations ^[1]. Research shows that Col7a1 gene homozygous knockout mice exhibit high mortality after birth, with hemorrhagic blisters appearing on the palms of the forepaws and hind paws within 24-48 hours, followed by severe RDEB symptoms ^[2]. This is one of the commonly used preclinical models for DEB research.

Col7a1 knockout (KO) mice, constructed by using gene editing technology to knock out the homologous gene Col7a1 of human COL7A1 in mice, serve as a research model for Dystrophic Epidermolysis Bullosa (DEB). Homozygous Col7a1 KO mice lack the expression of the Col7a1 gene and COL7A1 protein, and exhibit symptoms of skin redness and blistering on the palms of the fore and hind paws on the first day after birth, and die within three days after birth. Histological examination results show that the skin of Col7a1 KO mice exhibits significant subcutaneous edema, and there is a separation between the epidermis and dermis, which is roughly the same as the pathogenesis and pathological characteristics of human Dystrophic Epidermolysis Bullosa (DEB) in the clinic. Therefore, Col7a1 KO mice can be used for the mechanistic study of Dystrophic Epidermolysis Bullosa (DEB), as well as the development, screening, and evaluation of therapeutic drugs.

Strain Strategy

The Col7a1 gene is located on chromosome 9 of the mouse, comprising a total of 119 exons. Gene editing technology is used to knock out the 4th to 13th exon region of this gene.

Applications

Col7a1 KO mice can be used for the mechanistic study of Dystrophic Epidermolysis Bullosa (DEB), as well as the development, screening, and evaluation of therapeutic drugs.

Validation Data

1. Homozygous Col7a1 KO mice lack the expression of the Col7a1 gene

Figure 1. RT-qPCR detection of Col7a1 gene expression in homozygous Col7a1 KO mice (KO/KO) and wild-type mice (WT). The detection results show that compared with wild-type mice, the expression of the Col7a1 gene in homozygous Col7a1 KO mice is completely knocked out.

ND: Not detected.

2. Homozygous Col7a1 KO mice lack the expression of COL7A1 protein

Figure 2. Immunohistochemical detection of COL7A1 protein expression in wild-type mice (WT), heterozygous Col7a1 KO mice (HE), and homozygous Col7a1 KO mice (HO). The data show that COL7A1 protein is expressed in wild-type mice and heterozygous Col7a1 KO mice, but not in homozygous Col7a1 KO mice. In addition, the skin tissue of homozygous Col7a1 KO mice also exhibits separation between the epidermis and dermis.

3. Homozygous Col7a1 KO mice exhibit a phenotype of skin redness and blistering

Figure 3. Appearance monitoring of wild-type mice (WT) and homozygous Col7a1 KO mice (HO). Compared with wild-type mice, homozygous Col7a1 KO mice exhibit symptoms of skin redness and blistering on the first day after birth. The phenotype mainly appears on the palms of the fore and hind paws, and the mice die within three days after birth.

4. Homozygous Col7a1 KO mice exhibit significant subcutaneous edema

Figure 4. H&E staining detection of skin tissue in wild-type mice (WT), heterozygous Col7a1 KO mice (HE), and homozygous Col7a1 KO mice (HO). The data show that compared with wild-type mice and heterozygous Col7a1 KO mice, the skin of homozygous Col7a1 KO mice exhibits significant subcutaneous edema, and a separation between the epidermis and dermis is observed (indicated by the green asterisk).

Summary

The knockout of the Col7a1 gene in homozygous Col7a1 KO mice leads to the absence of COL7A1 protein expression, which in turn leads to a series of phenotypic changes, including the separation of the epidermis and dermis in skin tissue, and significant subcutaneous edema. Homozygous Col7a1 KO mice exhibit symptoms of skin redness and blistering on the first day after birth, with these symptoms primarily appearing on the palms of the fore and hind paws. Ultimately, these mice die within three days after birth. Therefore, Col7a1 KO mice can be used for the mechanistic study of Dystrophic Epidermolysis Bullosa (DEB), as well as the screening and evaluation of therapeutic drugs. 

Reference

[1] Dang N and Murrell DF. Mutation Analysis and Characterization of COL7A1 Mutations in Dystrophic Epidermolysis Bullosa. Exp Dermatol 2008;17(7) 553-568.

[2] Fritsch A, Loeckermann S, Kern JS, Braun A, Bösl MR, Bley TA, Schumann H, von Elverfeldt D, Paul D, Erlacher M, Berens von Rautenfeld D, Hausser I, Fässler R, Bruckner-Tuderman L. A hypomorphic mouse model of dystrophic epidermolysis bullosa reveals mechanisms of disease and response to fibroblast therapy. J Clin Invest. 2008 May;118(5):1669-79.