Molecular mechanisms of hair growth and shedding

摘要

Recent advances on hair growth and regression studies were reviewed. Hair follicle morphogenesis is governed by epithelial-mesenchymal interactions in embryonic skin, in which severa soluble factors and their receptors mediate signals between hair placode keratinocytes and fibroblasts of underlying dermal condensatoins. Placode pattern would set up by the FGF/BMP competition, then transcription factor Lfe-1 expresses both in the dermal condensation and hair placode to establish hair germs. Shh has several roles in hair formulation process, delineating placode boundary, supporting keratinocyte growth, and defining folliclde polarity. Wnt/#beta#-cateinin pathway is also important to induce hair placodes. In contrast to morphogenesis, the mechanism of hair regression is largely unclear. Two neurotrophic factors, BDNF and NT-4 could be involved in transition from anagen to catagen.