Bone Morphogenetic Protein Signaling Regulates Postnatal Hair Follicle Differentiation and Cycling

In the 2004 study, researchers used transgenic mice overexpressing the BMP inhibitor Noggin to explore the role of BMP signaling in hair follicle development and cycling. They found that misexpression of the Noggin transgene in hair follicle matrix cells resulted in a dramatic loss of hair postnatally, with a normal but shortened hair follicle morphogenesis followed by premature cycling and entry into the catagen phase. This led to a complete loss of hair shafts from secondary hair follicles, while primary hair follicles remained unaffected. The study demonstrated that BMP signaling is critical for the proper proliferation and differentiation of secondary hair follicles during late morphogenesis and that its inhibition can precipitate the onset of catagen and anagen phases. It also suggested that BMP signaling plays a role in lineage selection by progenitor cells in the skin, favoring hair follicle differentiation over sebaceous differentiation.