Niche-induced cell death and epithelial phagocytosis regulate hair follicle stem cell pool

Nature. 2015 Apr 6. doi: 10.1038/nature14306.

The hair follicle goes through periods of growth (anagen) and regression (catagen); in catagen, controlled cell death takes place in the epithelial part of the follicle. The Greco group showed earlier that during growth, highly mitotic cells drive the downward movement of the basal epithelium. In this work, the authors used several transgenic mouse models to study follicle regression. Mesa et al. showed that TGFβ growth factor signalling, which starts in the dermal papilla, causes cell death in the basal epithelium and the onset of catagen. The authors also showed that the epithelial debris left after apoptosis is cleared not by specialised phagocytes but by living basal epithelial cells acting as phagocytes, supporting a model of epithelial self-clearance.