Receptor Activator of NF-κB Stimulates the Proliferation of Epithelial Cells of the Epidermo-Pilosebaceous Unit

The study demonstrated that the receptor activator of NF-κB (RANK) played a crucial role in the proliferation of epithelial cells within the epidermo-pilosebaceous unit, particularly in hair follicle (HF) cycling and epidermal homeostasis. Mice deficient in RANK ligand (RANKL) were unable to initiate a new growth phase of the hair cycle, resulting in arrested epidermal homeostasis. Conversely, transgenic mice overexpressing RANK or those administered recombinant RANKL showed activation of the hair cycle and epidermal growth. RANK was expressed by hair follicle germ and bulge stem cells, as well as epidermal basal cells, which are essential for the renewal of the epidermo-pilosebaceous unit. The study concluded that RANK-RANKL signaling was critical for hair renewal and epidermal homeostasis, linking these two processes.