Galectin-7 overexpression is associated with the apoptotic process in UVB-induced sunburn keratinocytes . (skin /apoptosis / cutaneous tnmors)

摘要

Galectin-7 is a #BETA#-galactoside binding protein specifically expressed in stratified epithelia and notably in epidermis, but barely detectable in epidermal tumors and ahsent from squamous carcinoma cell lines. Galectin-7 gene is an early transcriptional target of the tumor suppressor pro- tein P53 [Polyak, K., Xia, Y., Zweier, J., Kinzler, K. & Vogelstein, B. (1997) Nature (London) 389, 300-305] . Because p53 transcriptional activity is increased by genotoxic stresses we have examined the possible effects of ultraviolet radiations (UVB) on galectin-7 expression in epidermal keratinocytes. The amounts of galectin-7 mRNA and protein are increased rapidly after UVB irradiation of epidermal keratinocytes. The increase of galectin-7 is parallel to P53 stabilization. UVB irradiation of skin reconstructed in vitro and of human skin ex vivo demonstrates that galectin-7 overexpression is associ- ated with sunburn/apoptotic keratinocytes. Transfection of a galectin-7 expression vector results in a significant increase in terminal deoxynuclcotidyltransferase-mediated UTP end la- beling-positive keratinocytes. The present findings demon- strate a keratinocyte-specific protein involved in the UV- induced apoptosis, an essential process in the maintenance of epidermal homeostasis.