Keratin is not only a Structural Protein in Hair: Keratin-mediated Hair Growth

Abstract Keratin is known to be a major protein in hair, but the biological function of keratin in hair growth is unknown, which led us to conduct a pilot study to elucidate biological function of keratin in hair growth via cellular interactions with hair forming cells. Here, we show hair growth is stimulated by intradermal injection of keratin into mice, and show that outer root sheath cells undergo transforming growth factor-β2-induced apoptosis, resulting in keratin exposure. Keratin exposure appears to be critical for dermal papilla cell condensation and hair germ formation as immunodepletion and silencing keratin prevent dermal papilla cell condensation and hair germ formation. Furthermore, silencing keratin in mice resulted in a marked suppression of anagen follicle formation and hair growth. Our study imply a new finding of how to initiate hair regeneration and suggests the potent application of keratin biomaterial for the treatment of hair loss.