Expression of Sfrp2 Is Increased in Catagen of Hair Follicles and Inhibits Keratinocyte Proliferation

Background: Hair follicles undergo cycles of repeated growth and regression. The Wnt pathway plays an important role in the regeneration and differentiation of hair follicles. Sfrp2, a Wnt inhibitor, is involved in the developmental and disease processes of various cells and tissues by modulating the Wnt pathway. Objective: The aim of this study was to understand the role of Sfrp2 in hair follicles through investigation of the Sfrp2 expression pattern in the skin and its effect on keratinocytes. Methods: We investigated Sfrp2 mRNA expression and the expression of the wnt target genes, Ccnd1 and C-myc, at various mouse hair follicle developmental stages using Real-time polymerase chain reaction. We also investigated the effect of SFRP2 on the proliferation and differentiation of mouse keratinocyte cells by adding SFRP2 protein or overexpressing Sfrp2 using an in vitro culture system. Results: Sfrp2 expression peaked in the catagen phase and remained high until telogen, and then declined at the beginning of the next anagen. An inverse relationship to Sfrp2 expression was found for the expression of the Wnt target genes, C-myc and Ccnd1. In addition, we also observed inhibited proliferation of mouse keratinocytes in the presence of SFRP2. Conclusion: These results suggest that Sfrp2 may play a role in the catagen phase by inhibiting the proliferation of keratinocyte and functioning as a Wnt inhibitor in keratinocytes.