NERVE GROWTH-FACTOR RESCUES PIGMENT-CELLS FROM ULTRAVIOLET-INDUCED APOPTOSIS BY UP-REGULATING BCL-2 LEVELS

Apoptosis plays an important role in eliminating dysfunctional damaged cells. For skin, the best characterized injurious environmental agent is ultraviolet (UV) irradiation. Most of the damaging UV irradiation is absorbed in the epidermis and leads to apoptosis of keratinocytes. However, epidermal melanocytes appear to be protected from UV-induced apoptosis. We now report that in pure cultures melanocytic cells under go characteristic apoptosis after physiologic UV exposures. However, n erve growth factor (NGF) supplementation protects them from this progr ammed cell death. Furthermore, we show that NGF protects melanocytic c ells from UV-induced apoptosis by upregulating BCL-2 protein in these cells and that prior downregulation of BCL-2 abrogates the NGF protect ive effect on melanocytes. Our data suggest that NGF, known to be cons titutively produced by epidermal keratinocytes and induced in these ce lls after UV irradiation, may preserve the population of cutaneous mel anocytes that would otherwise be depleted by casual sun exposure. (C) 1996 Academic Press, Inc.