The Human Cysteine Protease Cathepsin V Can Compensate for Murine Cathepsin L in Mouse Epidermis and Hair Follicles

Mice lacking cathepsin L exhibited skin issues such as periodic hair loss and epidermal hyperplasia. Researchers hypothesized that human cathepsin V, which shares 75% protein sequence identity with murine cathepsin L, could compensate for the absence of cathepsin L in mice. They created a transgenic mouse line expressing cathepsin V specifically in keratinocytes and crossed these with cathepsin L knockout mice. The resulting mice showed normalized epidermal proliferation, normal epidermal thickness, and a rescued hair phenotype. This indicated that cathepsin V could perform similar functions to cathepsin L in maintaining epidermis and hair follicles, suggesting its potential role in human skin.