Androgens and androgen receptor action in skin and hair follicles.

Beyond sexual functions, androgens exert their action in skin physiology and pathophysiology. Skin cells are able to synthesize most active androgens from gonadal or adrenal precursors and the enzymes involved in skin steroidogenesis are implicated both in normal or pathological processes. Even when the role of androgens and androgen receptor (AR) in skin pathologies has been studied for decades, their molecular mechanisms in skin disorders remain largely unknown. Here, we analyze recent studies of androgens and AR roles in several skin-related disorders, focusing in the current understanding of their molecular mechanisms in androgenetic alopecia (AGA). We review the molecular pathophysiology of type 2 5α-reductase, AR coactivators, the paracrine factors deregulated in dermal papillae (such as TGF-β, IGF 1, WNTs and DKK-1) and the crosstalk between AR and Wnt signaling in order to shed some light on new promising treatments.