Expression of the alpha and beta retinoic acid receptors in skin.

Retinoic acid receptor (RAR) -alpha and -beta transcripts are expressed in rat and human skin, and in rat and human dermal fibroblasts and keratinocytes in vitro. RAR-alpha transcripts (ca. 2.8 and 3.6 kb) were expressed in all tissues but were more abundant in dermis and dermal fibroblasts than in epidermis or keratinocytes. RAR-beta mRNA was expressed in skin, but patterns of expression differed between human and neonatal rat samples. In human dermal fibroblasts, keratinocytes and whole skin, two RAR-beta transcripts (ca. 3.1 and 3.4 kb) were expressed. Conversely, in neonatal rat skin, dermal fibroblasts, and keratinocytes only the smaller transcript was detectable and was more abundant in cultured cells than in whole tissue. These results suggest that retinoic acid may have complex, as yet undefined, RAR-mediated regulatory functions in both dermis and epidermis.