Ceramide Synthase 4 Regulates Stem Cell Homeostasis and Hair Follicle Cycling

The study demonstrated that Ceramide Synthase 4 (CerS4) was crucial for regulating hair follicle stem cell homeostasis and hair follicle cycling in mice. Inactivation of CerS4 led to premature activation of hair follicle bulge stem cells, resulting in prolonged anagen-like states and eventual hair loss in aged mice. This was linked to decreased bone morphogenetic protein (BMP) signaling and increased Wnt signaling, causing changes in hair follicle and sebaceous gland morphology, including increased proliferation and reduced quiescent stem cells. The findings suggested that CerS4 was essential for maintaining normal hair follicle cycling and preventing hair loss by regulating signaling pathways in the epidermis.