A Hairy Kinase

Alonso et al. identified Sgk3 as a kinase involved in hair growth, with its absence in mice leading to thin coats and short, abnormal hairs due to impaired follicle growth. While apoptosis, cell cycling, and differentiation timing appeared normal in the sgk3 mutant matrix, the recruitment of progenitor cells into the matrix was impaired, causing premature initiation of the shrinking phase before hair fully developed. This suggested that Sgk3 played a crucial role in maintaining the matrix cell supply, although it was unclear whether the matrix itself, the stem cell niche, or the outer root sheath utilized the kinase for this purpose.