[Expression pattern of retinoic acid receptor genes in normal human skin]

Expression pattern of the retinoic acid receptor (RAR) genes in normal human skin was investigated by in situ hybridization method. Using the riboprobes from cDNAs for three subtypes of RAR, we found that the RAR-alpha and the RAR-gamma genes were expressed in the epidermis. Significant expression of the RAR-beta gene was detected neither in the epidermis nor in the dermis. Expression of the RAR-alpha and -gamma genes was detected both in te basal cell layer and in the squamous cell layers. Moreover, the RAR-alpha and -gamma genes were expressed in the eccrine sweat glands as well. These results indicate that the target cells for retinoic acid (RA) in human skin are keratinocytes and the epithelial cells of epidermal appendages. These findings thus demonstrate that, among three subtypes of RAR, both RAR-alpha and RAR-gamma are essential for control of epidermal and epithelial cell differentiation in human skin.