Vitamin D and the Skin: Physiology and Pathophysiology

The document discussed the unique role of keratinocytes in the skin as the primary source of vitamin D and their ability to metabolize it into active forms, particularly 1,25(OH)2D, and respond via the vitamin D receptor (VDR). It highlighted that vitamin D and VDR regulate several skin functions, including inhibiting proliferation, stimulating differentiation, promoting innate immunity, regulating the hair follicle cycle, and suppressing tumor formation. The regulation of these actions involved various coregulator complexes such as the DRIP/Mediator complex, the SRC family, the inhibitor hairless (Hr), and β-catenin, each playing distinct roles in different VDR-regulated functions. The review aimed to explore these functions and the mechanisms behind their regulation.