Ineffective GSH regeneration enhances G6PD-knockdown Hep G2 cell sensitivity to diamide-induced oxidative damage.
Glucose-6-phosphate dehydrogenase (G6PD) has been recently found to play growth-regulatory roles in nucleated cells. To identify any other physiologic roles of G6PD, we generated G6PD-knockdown Hep G2 cells and investigated their susceptibility to oxidants. Hep G2 cells expressing shRNA against G6PD (Gi) were more susceptible to diamide-induced cytotoxicity than control cells expressing scrambled control shRNA (Sc). The level of reactive oxygen species in the Gi cells substantially exceeded that in Sc cells. This was accompanied by increased membrane peroxidation and the appearance of high-molecular-weight aggregates of membrane-associated cytoskeletal proteins in Gi cells. G6PD knockdown was associated with an impaired ability to regenerate glutathione. Diamide caused a considerable decrease in cellular glutathione level and a concomitant increase in glutathione disulfide in Gi cells. Consistent with this finding, N-acetylcysteine mitigated diamide-induced oxidative stress and cell death. Our findings suggest that G6PD confers protection against oxidant-induced cytotoxicity through effective glutathione regeneration.
Gao
Li-Ping
LP
Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, People's Republic of China.
Cheng
Mei-Ling
ML
Chou
Hsing-Jung
HJ
Yang
Yu-Hsiu
YH
Ho
Hung-Yao
HY
Chiu
Daniel Tsun-Yee
DT
D000975:Antioxidants / Q000494:pharmacology; D045744:Cell Line, Tumor; D019610:Cytoprotection / Q000187:drug effects / Q000235:genetics; D004249:DNA Damage / Q000187:drug effects / Q000235:genetics; D003958:Diamide / Q000633:toxicity*; D004351:Drug Resistance / Q000187:drug effects / Q000235:genetics; D004526:Efficiency / Q000502:physiology; D055785:Gene Knockdown Techniques; D005954:Glucosephosphate Dehydrogenase / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects / Q000235:genetics; D018384:Oxidative Stress / Q000187:drug effects* / Q000235:genetics; D034741:RNA, Small Interfering / Q000494:pharmacology; D011838:Radiation-Sensitizing Agents / Q000633:toxicity
D000975:Antioxidants; D034741:RNA, Small Interfering; D011838:Radiation-Sensitizing Agents; D003958:Diamide; D005954:Glucosephosphate Dehydrogenase; D005978:Glutathione