VDR Is an Essential Regulator of Hair Follicle Regression Through the Progression of Cell Death

The study "VDR is an essential regulator of hair follicle regression through the progression of cell death" demonstrates the critical role of the Vitamin D Receptor (VDR) in controlling hair follicle regression, or catagen. The absence of VDR was found to delay the onset of catagen, leading to extended hair growth. The research used Vdr-knockout mice and found that their hair cycle was halted during catagen, leading to the formation of "surviving epithelial strands" and preventing the completion of the catagen phase. This resulted in the hair follicles becoming trapped in a "paused-catagen" state, eventually transforming into dermal cysts. However, these mice retained the regenerative potential of their hair follicle stem cells (HFSCs) and dermal papilla (DP), even in the paused-catagen state. The study suggests that VDR-deficient alopecia in humans may also be due to catagen arrest and that it may be possible to treat this type of alopecia by inducing activation of the signaling between HFSCs and DP or by eliminating surviving epithelial strands before cyst formation.