Learning from nudity: Lessons from the nude phenotype

Lars Mecklenburg, Birte Tychsen, Ralf Paus

Research output: Contribution to journalReview article

61 Scopus citations

Abstract

In mice, rats, and humans, loss of function of Foxn1, a member of the winged helix/forkhead family of transcription factors, leads to macroscopic nudity and an inborn dysgenesis of the thymus. Nude (Foxn1nu/Foxn1nu) mice develop largely normal hair follicles and produce hair shafts. However, presumably because of a lack of certain hair keratins, the hair shafts that are generated twist and coil in the hair follicle infundibulum, which becomes dilated. Since hair shafts fail to penetrate the epidermis, macroscopic nudity results and generates the - grossly misleading - impression that nude mice are hairless. Here, we provide an overview of what is known on the role of Foxn1 in mammalian skin biology, its expression patterns in the hair follicle, its influence on hair follicle function, and onychocyte differentiation. We focus on the mechanisms and signaling pathways by which Foxn1 modulates keratinocyte differentiation in the hair follicle and nail apparatus and summarize the current knowledge on the molecular and functional consequences of a loss of function of the Foxn1 protein in skin. Foxn1 target genes, gene regulation of Foxn, and pharmacological manipulation of the nude phenotype (e.g. by cyclosporine A, KGF, and vitamin D3) are discussed, and important open questions as well as promising research strategies in Foxn1 biology are defined. Taken together, this review aims at delineating why enhanced research efforts in this comparatively neglected field of investigative dermatology promise important new insights into the controls of epithelial differentiation in mammalian skin.

Original languageEnglish (US)
Pages (from-to)797-810
Number of pages14
JournalExperimental Dermatology
Volume14
Issue number11
DOIs
StatePublished - Nov 1 2005
Externally publishedYes

    Fingerprint

Keywords

  • Foxn1
  • Hair
  • Keratins
  • Nail
  • Whn

ASJC Scopus subject areas

  • Dermatology

Cite this