Paracrine TGF-β Signaling Counterbalances BMP-Mediated Repression in Hair Follicle Stem Cell Activation

The study investigated the role of TGF-β2 in hair follicle stem cell (HFSC) activation and its interaction with BMP signaling. Researchers found that TGF-β2, produced by dermal papillae, activated Smad2/3 signaling in HFSCs, counteracting BMP's repressive effects. This balance was crucial for proper hair follicle regulation. Mice unable to sense TGF-β showed delayed hair regeneration, while TGF-β2 injections stimulated HFSC activation. The gene Tmeff1 was identified as a key mediator, acting as a BMP inhibitor. The findings highlighted the importance of TGF-β2 in mesenchymal-epithelial crosstalk necessary for HFSC activation and hair cycle progression, suggesting potential therapeutic targets for hair loss and alopecia.