Galectin-7 overexpression is associated with the apoptotic process in UVB-induced sunburn keratinocytes.
Galectin-7 is a beta-galactoside binding protein specifically expressed in stratified epithelia and notably in epidermis, but barely detectable in epidermal tumors and absent from squamous carcinoma cell lines. Galectin-7 gene is an early transcriptional target of the tumor suppressor protein 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 associated with sunburn/apoptotic keratinocytes. Transfection of a galectin-7 expression vector results in a significant increase in terminal deoxynucleotidyltransferase-mediated UTP end labeling-positive keratinocytes. The present findings demonstrate a keratinocyte-specific protein involved in the UV-induced apoptosis, an essential process in the maintenance of epidermal homeostasis.
Bernerd
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F
L'Oréal, Centre de Recherche Charles Zviak, 90 rue du Général Roguet, 92583 Clichy Cedex, France.
Sarasin
A
A
Magnaldo
T
T
D000818:Animals; D017209:Apoptosis; D002478:Cells, Cultured; D037161:Galectins; D006801:Humans; D020287:In Situ Nick-End Labeling; D015603:Keratinocytes / Q000378:metabolism / Q000528:radiation effects*; D037102:Lectins / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D011817:Rabbits; D013471:Sunburn / Q000378:metabolism*; D014466:Ultraviolet Rays / Q000009:adverse effects*
D037161:Galectins; C092525:LGALS7 protein, human; D037102:Lectins; D012333:RNA, Messenger