Expression of a skin cholesterol sulfotransferase, St2b2, is a trigger of epidermal cell differentiation.

1. St2b2, a mouse cytosolic sulfotransferase, predominantly catalyses epidermal cholesterol sulfation. St2b2 was found in the basement layer by immunohistochemical analysis of normal mouse skin. The highest expression level was detected in epidermis from 3-day-old mice and then decreased before maturation. There was a good correlation between expression levels of skin St2b2 and a differentiation marker, involucrin. 2. To understand the role of St2b2 in epidermal cell differentiation, recombinant St2b2 was expressed in primary epidermal cells. The expression of St2b2 enhanced the involucrin expression with an increase of cholesterol sulfate. Furthermore, by down-regulation of the St2b2 gene expression, involucrin was decreased in dorsal skin of 1-3-day-old mice by 67% of the control. 3. These results strongly suggest a possibility that St2b2 expression plays a trigger of epidermal cell differentiation by controlling cholesterol sulfate level in the cells.