A Small Indel Mutant Mouse Model of Epidermolytic Palmoplantar Keratoderma and Its Application to Mutant-specific shRNA Therapy

• Main Authors: Ya-Su Lyu, Pei-liang Shi, Xiao-Ling Chen, Yue-Xiao Tang, Yan-Fang Wang, Rong-Rong Liu, Xiao-Rui Luan, Yu Fang, Ru-Huan Mei, Zhen-Fang Du, Hai-Ping Ke, Erik Matro, Ling-En Li, Zhao-Yu Lin, Jing Zhao, Xiang Gao, Xian-Ning Zhang
• Format: Article
• Language: English
• Published: Elsevier 2016-01-01
• Series: Molecular Therapy: Nucleic Acids
• Subjects: epidermolytic palmoplantar keratoderma; indel; knock-in; Krt9 gene (mouse); shRNA therapy
• Online Access: http://www.sciencedirect.com/science/article/pii/S2162253117300306

Epidermolytic palmoplantar keratoderma (EPPK) is a relatively common autosomal-dominant skin disorder caused by mutations in the keratin 9 gene (KRT9), with few therapeutic options for the affected so far. Here, we report a knock-in transgenic mouse model that carried a small insertion–deletion (indel) mutant of Krt9, c.434delAinsGGCT (p.Tyr144delinsTrpLeu), corresponding to the human mutation KRT9/c.500delAinsGGCT (p.Tyr167delinsTrpLeu), which resulted in a human EPPK-like phenotype in the weight-stress areas of the fore- and hind-paws of both Krt9+/mut and Krt9mut/mut mice. The phenotype confirmed that EPPK is a dominant-negative condition, such that mice heterozygotic for the K9-mutant allele (Krt9+/mut) showed a clear EPPK-like phenotype. Then, we developed a mutant-specific short hairpin RNA (shRNA) therapy for EPPK mice. Mutant-specific shRNAs were systematically identified in vitro using a luciferase reporter gene assay and delivered into Krt9+/mut mice. shRNA-mediated knockdown of mutant protein resulted in almost normal morphology and functions of the skin, whereas the same shRNA had a negligible effect in wild-type K9 mice. Our results suggest that EPPK can be treated by gene therapy, and this has significant implications for future clinical application.