International Mammalian Genome Society

The 16th International Mouse Genome Conference (2002)


POSTER 140 - IMPAIRED HAIR FOLLICLE MORPHOGENESIS AND CYCLING WITH ABNORMAL EPIDERMAL DIFFERENTIATION IN NACKT MICE, A CATHEPSIN L DEFICIENT MUTATION

F Benavides
The University of Texas M.D. Anderson Cancer Center

1) Starost M, 1) Flores M, 1) Gimenez-Conti I, 2) Guénet JL, 1) Conti C
1) UT MD Anderson Cancer Center  2) Institut Pasteur

We previously described an autosomal recessive mutation named nackt (nkt) exhibiting partial alopecia associated with CD4+ T cell deficiency. Also, we recently reported that nkt (now Ctslnkt) comprises a deletion in the cathepsin L (Ctsl) gene. Another recent study reported that Ctsl knock out mice have CD4+ T cell deficiency and periodic shedding of hair, which recapitulate the nkt mutation and the old furless (fs) mutation. The current study focuses on the dermatological aspects of the nkt mutation. Careful histological analysis of skin development of homozygous nkt mice revealed a delayed hair follicle morphogenesis and late onset of the first catagen stage. The skin of Ctslnkt/Ctslnkt mice showed mild epidermal hyperplasia and hyperkeratosis, severe hyperplasia of the sebaceous glands, and structural alterations of hair follicles. Epidermal differentiation seems to be affected in nkt skin, with overexpression of involucrin and profilaggrin/filaggrin along with focal areas of keratin 6 expression in the interfollicular epidermis. Severe epidermal hyperplasia, acanthosis, orthokeratosis and hyperkeratosis were only observed in mice maintained in non pathogen-free environments. The analysis of Rag2 -/- Ctslnkt/Ctslnkt double mutant mice indicates that the skin defect remains under the absence of T and B-cells. This animal model provides in vivo evidence that cysteine protease cathepsin L plays a critical role in hair follicle morphogenesis and cycling, as well as epidermal differentiation.


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