TRYPSIN-INDUCED FOLLICULAR PAPILLA APOPTOSIS RESULTS IN DELAYED HAIR-GROWTH AND PIGMENTATION

Programmed cell death is a controlled process that leads to the elimin ation of single cells via apoptosis. Programmed cell death is fundamen tal to development, morphogenesis, and homeostasis. Proteases play a m ajor role in the death process. We have previously shown that a serine protease, secreted by a keratinocyte cell line, can induce apoptosis in numerous cell lines. Here we show that serine proteases can induce cell death in vivo as well. Using a synchronized hair growth mouse mod el, we show that topical trypsin treatment following depilation induce s cell death at the follicular papilla. This results in delaying hair growth and pigmentation. We speculate that trypsin might affect a rece ptor-mediated signaling pathway that leads to follicular papilla cell death. (C) 1997 Wiley-Liss, Inc.