June 2004
Role of TGF-beta2 in the human hair cycle.
Hibino T, Nishiyama T.
Shiseido Life Science Research Center, 2-12-1 Fukuura, Kanazawa-ku, Yokohama
236-8643, Japan.
Male pattern baldness is the result of premature entry into catagen due to
androgens. In order to prevent hair loss, it is important to understand two
critical steps, i.e., the induction mechanism of premature entry and the
regression process of catagen.
At the initiation, dihydrotestosterone (DHT) stimulates
synthesis of transforming growth factor-beta2 (TGF-beta2) in dermal papilla
cells. TGF-beta2 suppresses proliferation of epithelial cells and stimulates
synthesis of certain caspases.
Then TGF-beta2 triggers the intrinsic caspase network and
subsequently epithelial cells are eliminated through apoptotic cell death. TGF-beta
antagonists are effective in preventing catagen-like morphological changes and
in promoting elongation of hair follicles in vivo and in vitro.
These lines of evidence strongly suggest the presence of a "catagen
cascade" in male pattern baldness, involving: (1) the conversion of testosterone
to DHT by type II 5-alpha-reductase; (2) the synthesis of TGF-beta2 in dermal
papilla cells; and (3) the activation of the intrinsic caspase network.
These sequential events contribute to the shortening of the
human hair cycle.
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