Department of Pharmacology and Laboratory of Aging and Nervous Diseases, Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, College of Pharmaceutical Science, Soochow University, Suzhou 215123, China.
Institute of Pediatric Research, Children's Hospital of Soochow University; Suzhou 215025, China.
Free Radic Biol Med. 2017 Nov;112:433-444. doi: 10.1016/j.freeradbiomed.2017.08.011. Epub 2017 Aug 18.
TIGAR-regulated pentose phosphate pathway (PPP) plays a critical role in the neuronal survival during cerebral ischemia/reperfusion. Glucose-6-phosphate dehydrogenase (G6PD) is a rate-limiting enzyme in PPP and thus, we hypothesized that it plays an essential role in anti-oxidative defense through producing NADPH. The present study investigated the regulation and the role of G6PD in ischemia/reperfusion-induced neuronal injury with in vivo and in vitro models of ischemic stroke. The results showed that the levels of G6PD mRNA and protein were increased after ischemia/reperfusion. In vivo, lentivirus-mediated G6PD overexpression in mice markedly reduced neuronal damage after ischemia/reperfusion insult, while lentivirus-mediated G6PD knockdown exacerbated it. In vitro, overexpression of G6PD in cultured primary neurons decreased neuronal injury under oxygen and glucose deprivation/reoxygenation (OGD/R) condition, whereas knockdown of G6PD aggravated it. Overexpression of G6PD increased levels of NADPH and reduced form of glutathione (rGSH), and ameliorated ROS-induced macromolecular damage. On the contrary, knockdown of G6PD executed the opposite effects in mice and in primary neurons. Supplementation of exogenous NADPH alleviated the detrimental effects of G6PD knockdown, whereas further enhanced the beneficial effects of G6PD overexpression in ischemic injury. Therefore, our results suggest that G6PD protects ischemic brain injury through increasing PPP. Thus G6PD may be considered as potential therapeutic target for treatment of ischemic brain injury.
TIGAR 调节的戊糖磷酸途径 (PPP) 在脑缺血/再灌注期间神经元存活中起着关键作用。葡萄糖-6-磷酸脱氢酶 (G6PD) 是 PPP 的限速酶，因此，我们假设它通过产生 NADPH 在抗氧化防御中起重要作用。本研究通过缺血性中风的体内和体外模型研究了 G6PD 在缺血/再灌注诱导的神经元损伤中的调节和作用。结果表明，缺血/再灌注后 G6PD mRNA 和蛋白水平增加。在体内，用慢病毒介导的 G6PD 过表达可显著减轻缺血/再灌注损伤后的神经元损伤，而慢病毒介导的 G6PD 敲低则加剧了损伤。在体外，培养的原代神经元中 G6PD 的过表达可降低氧和葡萄糖剥夺/再氧合 (OGD/R) 条件下的神经元损伤，而 G6PD 的敲低则加重了损伤。G6PD 的过表达增加了 NADPH 的水平和还原型谷胱甘肽 (rGSH)，并减轻了 ROS 诱导的大分子损伤。相反，在小鼠和原代神经元中，敲低 G6PD 则产生相反的效果。外源性 NADPH 的补充减轻了 G6PD 敲低的有害影响，而进一步增强了 G6PD 过表达在缺血性损伤中的有益影响。因此，我们的结果表明 G6PD 通过增加 PPP 来保护缺血性脑损伤。因此，G6PD 可能被认为是治疗缺血性脑损伤的潜在治疗靶点。
