FC-05   ESTROGEN RECEPTORS ALPHA & BETA ARE EXPRESSED BY HUMAN EPIDERMAL AND HAIR FOLLICLE MELANOCYTES ‘IN SITU’ AND ‘IN VITRO’

DJ Tobin, EM Bridges,*AG Messenger, MJ Thornton. Dept. of Biomedical Sciences, University of Bradford, Bradford, England and *Dept Dermatology, Royal Hallamshire Hospital, Sheffield, England.

Estrogens have significant and distinct roles in hair and skin physiology: they can regulate the hair cycle and may have a direct role in the regulation of skin and hair pigmentation. The recent identification of ERbeta, distinct from the classical estrogen receptor (ERalpha), indicates the potential for enhanced diversity in the mechanism of estrogen action. Since the presence of ERalpha or ERbeta in melanocytes is unclear, we have examined the expression of ERalpha and ERbeta in human epidermal and follicular-derived melanocytes in situ and in vitro. ERalpha and ERbeta expression was examined in gp100-positive epidermal (EM) and hair bulb melanocytes (HFM) in normal occipital scalp of males (n=6) and females (n=6) by double immunofluorescence and in matched cell cultures of EM and HFM (n=2) and in melanocyte-fibroblast co-cultures. Results of this study have shown that the in situ expression of ERalpha is strong in differentiated EM and HFM and in amelanotic melanocytes of the outer root sheath. While levels of melanocyte expression for ERalpha was similar in male and female skin, the expression of ERbeta was more common and more intense in melanocytes of female skin. When cultured cells were examined, ERalpha and ERbeta expression was present in both male and female-derived melanocytes. Expression of both receptors was strongest in the nuclear and peri-nuclear regions of the cell and less so in the cytoplasm, where the pattern was commonly granular. Strongest staining was seen in cells with a more differentiated phenotype and was stronger in melanocytes than in co-cultured fibroblasts. This study demonstrates the presence of estrogen receptors in human EM and HFM both in situ and in vitro, suggesting a direct role for estrogens in the regulation of epidermal and hair follicle pigmentation. Since the presence of ERalpha and ERbeta in the same cell leads preferentially to heterodimerisation, their degree of co-localisation is significant, as they may act in a synergistic or antagonistic manner. Further studies are in progress to further elucidate the mechanism of action of estrogens in human melanocytes.