The Skin and Vitamin D

The document reviewed the role of the skin as the primary source of vitamin D for the body, highlighting its ability to convert 7-dehydrocholesterol to vitamin D3 under ultraviolet radiation. It discussed the importance of vitamin D in regulating bone mineral homeostasis and various non-classical actions such as cell differentiation, hormone secretion, and immune function. The skin's keratinocytes were noted for their unique ability to metabolize vitamin D to its active form and respond to it via the vitamin D receptor (VDR). The review explored how vitamin D and VDR regulate skin functions, including cell proliferation, differentiation, immunity, hair follicle cycle regulation, and tumor suppression, with regulation involving coregulators like DRIP, SRC, hairless (Hr), and β-catenin.