Glucose-6-phosphate dehydrogenase overexpression decreases endothelial cell oxidant stress and increases bioavailable nitric oxide.
OBJECTIVE
Glucose-6-phosphate dehydrogenase (G6PD), the principal source of NADPH, serves as an antioxidant enzyme to modulate the redox milieu and nitric oxide synthase activity. Deficient G6PD activity is associated with increased endothelial cell oxidant stress and diminished bioavailable nitric oxide (NO.). Therefore, we examined whether overexpression of G6PD would decrease reactive oxygen species accumulation and increase bioavailable NO. in endothelial cells.


RESULTS
Adenoviral-mediated gene transfer of G6PD increased G6PD expression, activity, and NADPH levels in bovine aortic endothelial cells (BAECs). BAECs overexpressing G6PD demonstrated a significant reduction in reactive oxygen species accumulation when exposed to hydrogen peroxide, xanthine-xanthine oxidase, or tumor necrosis factor-alpha compared with BAECs with basal levels of G6PD. BAECs overexpressing G6PD maintained intracellular glutathione stores when exposed to oxidants because of increased activity of glutathione reductase, an effect that was not observed in endothelial cells with normal G6PD activity. Overexpression of G6PD was also associated with enhanced nitric oxide synthase activity, resulting in elevated levels of cGMP, nitrate, and nitrite, and this response was increased after stimulation with bradykinin.


CONCLUSIONS
Overexpression of G6PD in vascular endothelial cells decreases reactive oxygen species accumulation in response to exogenous and endogenous oxidant stress and improves levels of bioavailable NO.
Leopold
Jane A
JA
Whitaker Cardiovascular Institute and Evans Department of Medicine, Boston University School of Medicine, 700 Albany St CABR W-507, Boston, MA 02118, USA. Jane.Leopold@bmc.org
Zhang
Ying-Yi
YY
Scribner
Anne W
AW
Stanton
Robert C
RC
Loscalzo
Joseph
J
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D001682:Biological Availability; D002417:Cattle; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism*; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism; D009249:NADP / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D018384:Oxidative Stress / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D019820:Xanthine / Q000494:pharmacology; D014969:Xanthine Oxidase / Q000494:pharmacology
D017382:Reactive Oxygen Species; D019820:Xanthine; D009569:Nitric Oxide; D009249:NADP; D005954:Glucosephosphate Dehydrogenase; D014969:Xanthine Oxidase; D005978:Glutathione; D006152:Cyclic GMP