Impaired Hair Follicle Morphogenesis and Cycling with Abnormal Epidermal Differentiation in Nackt Mice, a Cathepsin L-Deficient Mutation

The study examined the effects of a cathepsin L (CTSL) deficiency in nackt (nkt) mice, which resulted in partial alopecia, impaired hair follicle morphogenesis and cycling, and abnormal epidermal differentiation. The nkt mice displayed sparse hair, bald patches, and sebaceous gland hyperplasia, with delayed hair follicle development and increased expression of certain keratins and proteins. These skin defects were directly linked to the absence of CTSL, not lymphocyte-mediated processes, highlighting CTSL's crucial role in normal hair and skin development. The nkt mice served as a model for studying human skin disorders with similar characteristics, such as Papillon-Lefèvre syndrome.