Sox9 Increases the Proliferation and Colony-forming Activity of Outer Root Sheath Cells CulturedIn Vitro

BACKGROUND: β-catenin plays a pivotal role in hair follicle development and hair growth cycle. OBJECTIVE: The aim of this study was to identify β-catenin-regulated genes in cultured human hair outer root sheath (ORS) cells. METHODS: Primary cultured ORS cells were transduced with recombinant adenovirus expressing N-terminal truncated β-catenin (constitutive active form), and β-catenin-regulated genes were identified. RESULTS: Overexpression of the constitutively active form of β-catenin led to induction of Sox9 expression at both mRNA and protein levels. To investigate the potential role of Sox9, we made the recombinant adenovirus expressing green fluorescent protein-tagged Sox9, and then transduced into cultured ORS cells. Interestingly, Sox9 induced the expression of keratin 15, increased the proliferation of ORS cells in vitro, and enhanced colony-forming activity. CONCLUSION: Our results suggest that Sox9 is a β-catenin-regulated gene in ORS cells, and has potential importance in the regulation of hair follicle homeostasis.