EXPRESSION OF RETINOID NUCLEAR RECEPTOR SUPERFAMILY MEMBERS IN HUMAN HAIR-FOLLICLES AND ITS IMPLICATION IN HAIR-GROWTH

Since clinical evidence of hair loss and hair depigmentation following etretinate therapy has been reported, me decided to study the express ion levels of several members of the retinoid nuclear receptor superfa mily in dermal and epithelial compartments of the human hair follicle, Additionally, me evaluated the effects of several ligands for these r eceptors on human hair growth in culture in vitro, We observed that th e cellular/ cytoplasmic retinoic acid (RA) binding protein-II and the retinoid-X-receptor-a mere constantly and strongly expressed in both c ompartments at levels comparable to those of vitamin D receptor, In de rmal papilla cells, by contrast with RAR beta which was always express ed, RAR alpha and RAR gamma mere not constantly expressed, In dermal s heath fibroblasts, both RAR alpha, RAR beta and RAR gamma mRNAs mere m oderately expressed, while in the epithelial compartment, namely the p lucked hair, we observed the expression of the same genes in the absen ce of RAR beta, We also observed that RAR agonists all-trans RA and CD 367 inhibited the survival of human hair follicles in culture in vitro , while RXR agonist CD2425 stimulated hair growth and survival at leve ls comparable to those of 1 alpha,25-dihydroxyvitamin D-3, suggesting that RXR agonists might stimulate hair growth in humans in vive.