Detection of mRNA transcripts for retinoic acid, vitamin D3, and thyroid hormone (c-erb-A) nuclear receptors in human skin using reverse transcription and polymerase chain reaction

Abstract

Differentiation of keratinocytes involves both non-genomic and genomic events. The genomic effects are regulated by ligand dependent transcription factors, e.g. the steroid/thyroid superfamily of nuclear receptors. In the present study we examined mRNA expression of receptors for retinoic acid, thyroid hormone, and vitamin D3 in normal human skin and cultured keratinocytes using reverse transcription coupled to the polymerase chain reaction. The vitamin D3 receptor and the retinoic acid receptor (RAR) γ together with the more distantly related RXRα were amplified extensively in skin and cultured keratinocytes. RARα was amplified at a lower level, and RARβ was almost undetectable. The thyroid hormone receptors α1 and β1 were weakly amplified, but to comparable levels. Because receptors for retinoic acid, thyroid hormones, and vitamin D3 are all expressed in human epidermis differentiation of keratinocytes is probably regulated at transcriptional level by these molecules. It remains to be seen whether alterations in the expression of the nuclear receptors occur in certain skin disorders.