Abstract
GRP78 has been reported to be a molecular chaperon whose expression is increased in response to endoplasmic reticulum stress such as glucose starvation and anoxia. In this annual meeting of the last year, we suggested that GRP78 is involved in the resistance of human cells to far-ultraviolet light (UVC) lethality. In the present study, we investigated whether GRP78 regulates the susceptibility of human cells to UVC mutagenicity and the mechanisms underlying the GRP78-invloved UVC resistance. We established human cells, in which the expression levels of GRP78 proteins were decreased by transfection of antisense cDNA of GRP78. The sensitivity of the cells to UVC mutagenicity was examined by ouabain-resistance test. The removal kinetics of the UVC-damaged DNA were also analyzed by ELISA assay. The transfected cells showed higher sensitivities to UVC mutagenicity and lower removal ability of the damaged DNA than did the vector control cells. These findings suggest that GRP78 is involved in the UVC resistance of human cells possibly via DNA repair process. [J Radiat Res 44:414 (2003)]
