Role of G6PD in Myocardial Oxidant Stress & Hypertrophy

G6PD 在心肌氧化应激中的作用

• 批准号: 6727154
• 负责人: Ronglih Liao
• 金额: $ 36.34万
• 依托单位: BOSTON UNIVERSITY MEDICAL CAMPUS
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-05-01 至 2008-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6727154
• 关键词: NAD(H) phosphate; SDS polyacrylamide gel electrophoresis; antioxidants; cardiac myocytes; cardiovascular agents; cytoprotection; enzyme complex; enzyme mechanism; glucose 6 phosphate dehydrogenase; glutathione; laboratory mouse; laboratory rabbit; mass spectrometry; matrix assisted laser desorption ionization; myocardial ischemia /hypoxia; myocardium disorder; oxidative stress; pentose phosphate; protein structure; protein structure function; tissue /cell culture

DESCRIPTION (provided by applicant): Reactive oxygen species (ROS) play a significant role in the pathophysiology of cardiovascular disease. Though ROS have been conventionally regarded as harmful and toxic by-products of cellular aerobic metabolism, emerging evidence has suggested that ROS also function as crucial intracellular signaling molecules, capable of regulating cellular growth and hypertrophy. NADPH plays multiple roles in the regulation of ROS levels through its actions as a cofactor for antioxidant enzymes. NADPH also serves as a substrate for the generation of ROS by key enzymes that modulate cell growth/hypertrophy via ROS-dependent signaling pathways. In this context, the role of glucose-6-phosphate dehydrogenase (G6PD) and the pentose phosphate pathway (PPP) becomes extremely important. G6PD functions as the first and rate-limiting enzyme in the PPP, responsible for the generation of NADPH in a reaction coupled to the oxidation of glucose-6-phosphate. Although G6PD is ubiquitously expressed, the role of G6PD in regulating antioxidant defense and cell signaling pathways in the heart remains unknown. Our preliminary data suggest that inhibition of G6PD depletes antioxidant reserves and increases susceptibility to acute oxidative injury in cardiomyocytes, consistent with the role of G6PD as an antioxidant enzyme. Conversely, we have found that inhibition of G6PD also results in marked attenuation of mitogen-activated protein kinase ERK1/2 activation and cardiomyocyte hypertrophy following alpha1-adrenergic receptor stimulation, supporting the role of G6PD in modulating cell growth/hypertrophy. These observations led to our central hypothesis that G6PD, the rate-limiting enzyme in the pentose phosphate pathway, regulates cytosolic NADPH levels, and thereby (1) protects the heart from oxidative injury and (2) modulates myocardial growth/hypertrophy. We will utilize a multidisciplinary approach of in-vitro (isolated adult cardiomyocytes), ex-vivo (isolated Langendorff perfused hearts) and in-vivo (mouse models) methods to define the importance of the PPP and G6PD in the heart as well as explore its potential as a therapeutic target for the treatment of cardiovascular diseases associated with oxidative stress.

描述（由申请人提供）：活性氧（ROS）在心血管疾病的病理生理学中发挥着重要作用。尽管 ROS 传统上被认为是细胞有氧代谢的有害且有毒的副产品，但新的证据表明，ROS 还可以作为重要的细胞内信号分子，能够调节细胞生长和肥大。 NADPH 作为抗氧化酶的辅助因子，在 ROS 水平的调节中发挥多种作用。 NADPH 还可以作为通过 ROS 依赖性信号通路调节细胞生长/肥大的关键酶产生 ROS 的底物。在这种情况下，葡萄糖-6-磷酸脱氢酶（G6PD）和磷酸戊糖途径（PPP）的作用变得极其重要。 G6PD 是 PPP 中的第一个限速酶，负责在与 6-磷酸葡萄糖氧化相关的反应中生成 NADPH。尽管 G6PD 普遍表达，但 G6PD 在调节心脏抗氧化防御和细胞信号通路中的作用仍不清楚。我们的初步数据表明，抑制 G6PD 会耗尽抗氧化剂储备并增加心肌细胞对急性氧化损伤的敏感性，这与 G6PD 作为抗氧化酶的作用一致。相反，我们发现抑制 G6PD 也会导致丝裂原激活蛋白激酶 ERK1/2 活化显着减弱，并在 α1-肾上腺素能受体刺激后导致心肌细胞肥大，这支持了 G6PD 在调节细胞生长/肥大中的作用。这些观察结果得出我们的中心假设：G6PD（磷酸戊糖途径中的限速酶）调节胞质 NADPH 水平，从而 (1) 保护心脏免受氧化损伤，(2) 调节心肌生长/肥大。我们将利用体外（分离的成体心肌细胞）、离体（分离的 Langendorff 灌注心脏）和体内（小鼠模型）方法的多学科方法来定义 PPP 和 G6PD 在心脏中的重要性并探索其作为治疗与氧化应激相关的心血管疾病的治疗靶点的潜力。