Role of Vitamin D Receptor in Adult Hair Follicle Cycling

The study investigated the role of the vitamin D receptor (VDR) in adult hair follicle cycling, revealing that the absence or alteration of VDR in both humans and mice led to a failure in adult hair follicle cycling due to a defect in anagen re-initiation. This effect was specific to adult hair follicles, as embryonic hair development remained unaffected. The research identified that VDR −/− mouse hair follicles showed a lack of induction of key regulators like transforming growth factor-beta receptor 2 and noggin, decreased expression of versican, and changes in other markers such as increased filaggrin and decreased keratin krt2–16. These findings suggested a disruption in the balance of cell proliferation and differentiation, supporting the model that VDR plays a crucial role in regulating this balance in hair follicle cycling.