Ultraviolet B irradiation increases the expression of cornulin and retepin in human skin xenotransplants

Abstract

Abstract Cornulin (CRNN) and repetin (RPTN) belong to the fused-type S100 protein family. Although these proteins have been reported to be expressed in the granular layer of the epidermis and are suggested to be associated with barrier formation in the epidermis, the exact function of these proteins remains unclear. The present study examined the effects of UVB irradiation on the CRNN and RPTN expression in human skin xenotransplantation. The expression of CRNN increased in the granular layer of UVB-irradiated skin two days after UVB irradiation in comparison to sham-irradiated skin. Interestingly, CRNN signals were observed not only in the cytoplasm but also in the peripheral region of the granular keratinocytes. In contrast, RPTN was rarely expressed in sham-irradiated skin; however, RPTN signals were markedly increased in the granular layer of UVB-irradiated skin. The number of RPTN-positive keratinocytes on day 2 after UVB irradiation was significantly higher than that in the sham-irradiated skin. Accordingly, the present study demonstrated that CRNN and RPTN are novel proteins whose expression can be increased by UVB irradiation. In addition, we speculate that the role of CRNN and RPTN in barrier formation of the epidermis may differ according to the expression pattern of these proteins in UVB-irradiated skin.