Role of the Vitamin D Receptor in Hair Follicle Biology

The study explored the role of the vitamin D receptor (VDR) in hair follicle biology, demonstrating that the absence of VDR leads to alopecia. Research in VDR null mice showed no abnormalities during hair follicle morphogenesis but revealed an inability to initiate new hair cycles post-morphogenesis, resulting in no new hair growth. Transgenic mice studies indicated that VDR expression in keratinocytes could prevent alopecia, highlighting the necessity of VDR for maintaining hair follicle homeostasis. Further investigations identified the critical role of the DNA binding domain of VDR, as mice lacking this domain exhibited similar alopecia to VDR null mice. Mutant VDRs that could not perform ligand-dependent transactivation still prevented alopecia, suggesting that unliganded VDR plays a role in hair follicle maintenance.