Mechanical Force Activation of TGF-β Signaling Controls Hair Follicle Regression

The study "Mechanical force activation of TGF-β signaling controls hair follicle regression" reveals that the dermal sheath smooth muscle, which surrounds all hair follicles, regulates cell death during hair follicle regression through the mechanosignaling of the transforming growth factor (TGF)-β pathway. In the hair growth phase, the dermal sheath secretes TGF-β as an inactive complex that is stored in the basement membrane extracellular matrix. During hair follicle regression, the sheath contracts, releasing TGF-β, which then signals to progenitor cells to regulate cell death. The study identifies Integrin-alpha-V on the sheath cell surface as the molecular link connecting sheath cell forces with extracellular matrix TGF-β release. This suggests that the dermal sheath acts as a mechanosignaling niche controlling the reduction of the progenitor pool through mechanical force, signal activation, and cell-cell communication.