Metabolic And Cellular Analysis Of Alopecia In Vitamin D Receptor Knockout Mice

The study investigated the role of the vitamin D receptor (VDR) in hair growth by using VDR-null mice raised in a UV-free environment and fed a diet lacking vitamin D metabolites. Despite undetectable levels of vitamin D metabolites, these mice developed alopecia, indicating that the absence of VDR, rather than vitamin D deficiency, was responsible for hair loss. Hair-reconstitution assays showed that both keratinocytes and dermal papilla cells lacking VDR could still form hair follicles, but VDR-null keratinocytes failed to maintain hair growth and initiate the anagen phase, leading to hair loss. This suggested that VDR's role in hair maintenance was independent of its ligand, and the absence of VDR in keratinocytes was crucial for the observed hair-cycle defect.