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NADPH Oxidase, Mitochondrial Dysfunction and Diabetic Retinopathy

NADPH 氧化酶、线粒体功能障碍和糖尿病视网膜病变

基本信息

批准号：
8444408
负责人：
RENU A. KOWLURU
金额：
$ 36.1万
依托单位：
WAYNE STATE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-04-01 至 2016-02-28
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8444408
关键词：
Address Age Anabolism Apoptosis Apoptotic Attenuated Biological Models Blindness Blood Vessels Blood capillaries Cell Survival Cells Ceramides Characteristics Complications of Diabetes Mellitus Cytosol DNA Data Development Diabetes Mellitus Diabetic Retinopathy Diabetic mouse Disease Drug Targeting Effectiveness Endothelial Cells Event Fright Fumonisin B1 Functional disorder G-Protein Signaling Pathway Generations Glucose Holoenzymes Human Hyperglycemia Hyperlipidemia In Vitro Inflammatory Laboratories Lesion Lipids Mediating Membrane Mitochondria Modeling Molecular Mus NADPH Oxidase Obesity Oxidative Stress Palmitates Pathogenesis Pathology Pathway interactions Patients Pericytes Phagocytes Phosphorylation Rattus Reaction Reactive Oxygen Species Regulation Research Retina Retinal Retinal Diseases Retinopathy of Prematurity Rodent Model Role Saturated Fatty Acids Severities Signal Pathway Signal Transduction Signaling Protein Source Specific qualifier value Staging Superoxides Testing Therapeutic Vascular Endothelial Growth Factors Vision Work base capillary cytochrome c diabetic diabetic rat in vivo Model inhibitor/antagonist insight mitochondrial dysfunction mutant novel oxidative damage prenylation prevent retinal apoptosis retinal damage young adult

项目摘要

Retinopathy remains one of the most feared debilitating complications of diabetes. In the pathogenesis of diabetic retinopathy, superoxide levels are significantly elevated, mitochondria are dysfunctional and their DNA is damaged resulting in a vicious cycle of increased superoxide accumulation. Emerging evidence implicates NADPH oxidase (Nox) also as a potential source of reactive oxygen species (ROS) with detrimental effects on cell survival. Our preliminary data show that hyperglycemia activates Rac1/Nox2 signaling axis in the retina and its capillary cells prior to mitochondrial dysregulation, suggesting that Nox2 activation represents an early event in diabetes-induced mitochondrial dysfunction and cell apoptosis. Thus, our overall hypothesis is that Nox2-derived ROS in diabetes damage retinal mitochondria leading to their dysfunction, and apoptosis of capillary cells is accelerated resulting in the development of diabetic retinopathy. We propose to test this hypothesis methodically by addressing complementary questions proposed under three specific aims. The first aim will investigate the mechanism(s) by which hyperglycemia activates Nox2 in the retina, and will test the hypothesis that in hyperglycemia Rac1-mediated Nox2 activation and ROS generation initiate mitochondrial damage and cellular apoptosis. Since the severity of retinopathy is associated directly with hyperlipidemia, in the second aim, the mechanism(s) by which lipotoxic conditions promote the development of diabetic retinopathy will be investigated. Our working model predicts that lipotoxic conditions promote Rac1-mediated Nox2 activation and ROS generation to initiate mitochondrial damage and cellular apoptosis. The third aim will determine the effect of regulation of Nox2 on the development of diabetic retinopathy, and will test the hypothesis that inhibition of Nox2 will attenuate mitochondrial damage and subsequent development of diabetic retinopathy. These proposed studies are based on compelling preliminary data generated via multi-disciplinary collaborative efforts between two PIs using valid in vitro and in vivo model systems. We propose to utilize known selective inhibitors of the Tiam1/Rac1/Nox2 signaling pathways; data from these studies will be confirmed via the use of inactive mutants and siRNAs for key signaling proteins in this pathway. In vitro findings will be further validated in in vivo models (stz-induced diabetic rats and mice, and Zucker diabetic fatty rats), and also in the retina from human donors with diabetic retinopathy. We expect to demonstrate the role of Rac-1-mediated Nox2 derived ROS as the 'initiator' of mitochondrial dysfunction in the pathogenesis of retinopathy. This should reveal novel targets for therapies to prevent retinopathy in the early stages of its development, and offer patients additional therapeutic means to prevent/retard this sight-threatening complication of diabetes.

视网膜病变仍然是糖尿病最令人畏惧的衰弱并发症之一。在疾病的发病机制中糖尿病视网膜病变，超氧化物水平显著升高，线粒体功能障碍，其DNA 被破坏，导致超氧化物积累增加的恶性循环。新出现的证据表明 NADPH氧化酶(NOx)也是活性氧物种(ROS)的潜在来源，对细胞存活。我们的初步数据显示，高血糖激活了视网膜中的rac1/NOX2信号轴和它的毛细血管细胞线粒体失调之前，提示NOX2的激活代表早期糖尿病引起的线粒体功能障碍和细胞凋亡事件。因此，我们的总体假设是糖尿病患者NOX2来源的ROS损伤视网膜线粒体，导致线粒体功能障碍和细胞凋亡毛细血管细胞的生长加速，导致糖尿病视网膜病变的发生。我们建议通过回答下面提出的补充问题来系统地检验这一假设三个具体目标。第一个目的是研究高血糖激活NOX2的机制(S)。视网膜，并将检验假设，在高血糖中，rac1介导的NOX2激活和ROS 基因启动线粒体损伤和细胞凋亡。由于视网膜病变的严重程度与直接与高脂血症，在第二个目的，机制(S)的脂肪毒性条件促进将对糖尿病视网膜病变的发展进行调查。我们的工作模型预测，脂毒性条件促进rac1介导的NOX2活化和ROS生成，启动线粒体损伤和细胞细胞凋亡。第三个目的将确定NOX2在糖尿病发展中的调节作用并将检验抑制NOX2将减轻线粒体损伤和随后发展为糖尿病视网膜病变。这些拟议的研究基于通过多学科产生的令人信服的初步数据使用有效的体外和体内模型系统的两个PI之间的合作努力。我们打算利用已知的Tiam1/rac1/NOX2信号通路的选择性抑制剂；这些研究的数据将是通过对这一途径中的关键信号蛋白使用非活性突变体和siRNAs进行确认。离体这些发现将在体内模型中进一步得到验证(STZ诱导的糖尿病大鼠和小鼠，以及Zucker糖尿病脂肪大鼠)，以及患有糖尿病视网膜病变的人类捐赠者的视网膜。我们希望展示 RAC-1介导的NOX2来源的ROS是线粒体功能障碍的始发者视网膜病变。这应该揭示在其早期阶段预防视网膜病变的治疗的新靶点发展，并为患者提供额外的治疗手段来预防/延缓这种威胁视力的疾病糖尿病并发症。