Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, Alabama, USA.
Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Université Laval, Québec City, Quebec, Canada.
FASEB J. 2024 Mar 31;38(6):e23556. doi: 10.1096/fj.202302559R.
PARP-1 over-activation results in cell death via excessive PAR generation in different cell types, including neurons following brain ischemia. Glycolysis, mitochondrial function, and redox balance are key cellular processes altered in brain ischemia. Studies show that PAR generated after PARP-1 over-activation can bind hexokinase-1 (HK-1) and result in glycolytic defects and subsequent mitochondrial dysfunction. HK-1 is the neuronal hexokinase and catalyzes the first reaction of glycolysis, converting glucose to glucose-6-phosphate (G6P), a common substrate for glycolysis, and the pentose phosphate pathway (PPP). PPP is critical in maintaining NADPH and GSH levels via G6P dehydrogenase activity. Therefore, defects in HK-1 will not only decrease cellular bioenergetics but will also cause redox imbalance due to the depletion of GSH. In brain ischemia, whether PAR-mediated inhibition of HK-1 results in bioenergetics defects and redox imbalance is not known. We used oxygen-glucose deprivation (OGD) in mouse cortical neurons to mimic brain ischemia in neuronal cultures and observed that PARP-1 activation via PAR formation alters glycolysis, mitochondrial function, and redox homeostasis in neurons. We used pharmacological inhibition of PARP-1 and adenoviral-mediated overexpression of wild-type HK-1 (wtHK-1) and PAR-binding mutant HK-1 (pbmHK-1). Our data show that PAR inhibition or overexpression of HK-1 significantly improves glycolysis, mitochondrial function, redox homeostasis, and cell survival in mouse cortical neurons exposed to OGD. These results suggest that PAR binding and inhibition of HK-1 during OGD drive bioenergetic defects in neurons due to inhibition of glycolysis and impairment of mitochondrial function.
聚腺苷二磷酸核糖聚合酶 1（PARP-1）过度激活会导致不同细胞类型（包括脑缺血后的神经元）中过多的 PAR 生成，从而引发细胞死亡。糖酵解、线粒体功能和氧化还原平衡是脑缺血中改变的关键细胞过程。研究表明，PARP-1 过度激活后产生的 PAR 可以与己糖激酶-1（HK-1）结合，导致糖酵解缺陷和随后的线粒体功能障碍。HK-1 是神经元己糖激酶，催化糖酵解的第一个反应，将葡萄糖转化为葡萄糖-6-磷酸（G6P），G6P 是糖酵解和戊糖磷酸途径（PPP）的共同底物。PPP 通过 G6P 脱氢酶活性对维持 NADPH 和 GSH 水平至关重要。因此，HK-1 的缺陷不仅会降低细胞的生物能量，还会由于 GSH 的消耗而导致氧化还原失衡。在脑缺血中，PAR 介导的 HK-1 抑制是否会导致生物能量缺陷和氧化还原失衡尚不清楚。我们使用氧葡萄糖剥夺（OGD）在小鼠皮质神经元中模拟神经元培养物中的脑缺血，并观察到 PAR 形成导致 PARP-1 激活改变神经元中的糖酵解、线粒体功能和氧化还原平衡。我们使用 PARP-1 的药理学抑制和野生型 HK-1（wtHK-1）和 PAR 结合突变体 HK-1（pbmHK-1）的腺病毒过表达来实现。我们的数据表明，PAR 抑制或 HK-1 的过表达可显著改善暴露于 OGD 的小鼠皮质神经元中的糖酵解、线粒体功能、氧化还原稳态和细胞存活。这些结果表明，在 OGD 期间 PAR 结合和 HK-1 的抑制通过抑制糖酵解和损害线粒体功能导致神经元中的生物能量缺陷。
