Retinoic acid and mouse skin morphogenesis. I. Expression pattern of retinoic acid receptor genes during hair vibrissa follicle, plantar, and nasal gland development

Abstract

The spatial and temporal expression of the nuclear retinoic acid receptors alpha, beta, and gamma (RAR-α, β, and γ) was compared by in situ hybridization during hair vibrissa follicle and nasal and plantar eccrine gland morphogenesis in mouse embryo. The RAR-α and RAR-γ transcripts are abundant in the dermal papilla cells of the hair vibrissa when these cells elicit epidermal hair placode (12.5-d embryos) and hair follicle (13.5-d embryos) formation. Both these transcripts are also abundant in the dermal cells of the plantar foot pad at the initiation stage (17.5-d embryos) of glandular morphogenesis. In epidermal cells, the distribution of RAR-γ transcripts increases in parallel with hair vibrissa follicle and sweat gland differentiation, and thus may be part of the epidermal response to the dermal instructions. The RAR-β signal is barely above control level during both hair vibrissa and plantar gland morphogenesis. By contrast, during nasal gland formation (12.5- to 15.5-d embryos), the RAR-β signal reaches a high level in mesenchymal cells, whereas the RAR-α transcripts are present in both epithelial and mesenchymal cells. These results suggest a role for RAR-α and RAR-γ in the epidermal-dermal interactions that lead to hair follicle and plantar gland morphogenesis, whereas the nasal gland development implies RAR-α and RAR-β gene expression. This should be correlated with the expression of the RAR-β gene that was previously shown to be linked to the RA-induced glandular metaplasia of hair vibrissa follicles. © 1994.