602 Sox13 is a novel marker for hair follicle development and differentiation

Abstract

The Sry-related high-mobility-group box (Sox) gene encodes a transcription factor family that plays crucial roles in the determination of cell fate and organogenesis. Sox13, a group D member of the Sox family, is expressed in various tissues such as brain, cartilage, hair, kidney, pancreas, liver, kidney and blood vessels. However, knowledge of the biological roles of Sox13 is largely limited. To examine the precise expression domains of Sox13 protein and its role in mouse development, we generated Sox13-LacZ-knock-in mice (Sox13LacZ/+), in which the Sox13 coding sequence was disrupted by an in-frame insertion of the b-galactosidase (LacZ) gene. Using the knock-in mice, we examined spatiotemporal expression patterns of Sox13 in the hair follicle and its role in hair development. X-gal staining in Sox13LacZ/+ embryos revealed that Sox13 is initially expressed in the epithelial portion of the placode at E14.5, and subsequently in the hair germ and the hair peg during hair follicle morphogenesis. Immunohistochemistry with an anti-b-galactosidase antibody and anti-hair keratin antibodies that specifically mark the different layers of the hair follicle revealed that during the postnatal phases of hair development Sox13 was predominantly expressed in the outer root sheath. However, the integumentary structures of Sox13LacZ/LacZ mice were grossly and histologically normal. These results suggest that although Sox13 is dispensable for epidermal and adnexal development, Sox13 is a novel marker for early hair follicle development and differentiation.