Transfection with glutathione-dependent dehydroascorbate reductase genes exerts cytoprotective effects against hydroperoxide- induced cell injury through vitamin C regeneration and oxidative-stress diminishment

摘要

To evaluate the potential for utilization of overexpression of glutathione (GSH)-dependent dehydroascorbate (DehAsc) reductase (DHAR) as a tool to alleviate deleterious effects induced by an oxidative stress, the effect of overexpressed DHAR on tert-butylhydroperoxide (t-BuOOH)-induced cell injury was examined using DHAR gene (dhar)-transfected Chinese hamster ovary (CHO) cells. The transfected dhar products-derived DHAR was shown to be expressed all over the cytoplasm rather than in the nucleus, and repressed t-BuOOH-induced cell death, DNA strand cleavages, and intracellular reactive oxygen species (ROS)-generation in cells pretreated with DehAsc plus GSH isopropylester, but not without such pretreatment in contrast to no repression in their vector-transfected counterparts with such pretreatment. Upon the similar pretreatment, the intracellular levels of both ascorbic acid (Asc) and total vitamin C (Asc plus DehAsc) were 1.4- to 1.7-fold higher in dhar-transfected cells than in the vector- transfectants. Thus, our results suggest that overexpressed DHAR exerts cytoprotective effects against hydroperoxide-induced cell injury, and that more abundant intracellular Asc accumulation induced by expressionof exogenous dhar may be involved in the mechanism.