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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：
8316580
负责人：
RENU A. KOWLURU
金额：
$ 38万
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/8316580
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 Delivery Systems 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

DESCRIPTION (provided by applicant): 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 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. PUBLIC HEALTH RELEVANCE: Diabetic retinopathy, a slow progressing, is the most frequent cause of blindness among young adults. Despite the cutting edge research to explore how the disease develops, the actual molecular and cellular mechanisms underlying this lesion remain elusive. This proposal is focused on understanding potential damaging mechanisms responsible for the development of diabetic retinopathy through systematic analysis of a specified signaling pathway, Tiam1-Rac1-Nox2, which increases oxidative stress and damages mitochondria. We will test the "initiator" roles for Nox2-derived ROS in mitochondrial dysfunction, and the development of diabetic retinopathy. The application represents a multi-disciplinary collaborative effort between two well-established laboratories actively focused on G-protein signaling pathways and mitochondrial dysfunction in the pathogenesis of diabetic retinopathy. Data from this study are expected to identify novel drug targets for halting the progression of this blinding disease in human diabetes.

描述（由申请人提供）：视网膜病变仍然是糖尿病最可怕的衰弱并发症之一。在糖尿病视网膜病变的发病机制中，超氧化物水平显著升高，线粒体功能障碍，其DNA受损，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（ROS）的潜在来源，对细胞存活有不利影响。我们的初步数据表明，高血糖激活Rac 1/Nox 2信号轴在视网膜和毛细血管细胞线粒体失调之前，这表明Nox 2激活代表糖尿病诱导的线粒体功能障碍和细胞凋亡的早期事件。因此，我们的总体假设是糖尿病中的Nox 2衍生的ROS损伤视网膜线粒体，导致其功能障碍，并且毛细血管细胞的凋亡加速，导致糖尿病视网膜病变的发展。我们建议通过解决三个具体目标下提出的补充问题来系统地测试这一假设。第一个目的是研究高血糖症激活视网膜中Nox 2的机制，并检验高血糖症中Rac 1介导的Nox 2激活和ROS产生启动线粒体损伤和细胞凋亡的假设。由于视网膜病变的严重程度与高脂血症直接相关，因此在第二个目的中，将研究脂毒性条件促进糖尿病视网膜病变发展的机制。我们的工作模型预测，脂毒性条件下促进Rac 1介导的Nox 2激活和ROS的产生，启动线粒体损伤和细胞凋亡。第三个目标将确定调节Nox 2对糖尿病视网膜病变发展的影响，并将测试抑制Nox 2将减弱线粒体损伤和随后糖尿病视网膜病变发展的假设。这些拟定研究基于两名PI使用有效的体外和体内模型系统通过多学科协作产生的令人信服的初步数据。我们建议利用Tiam 1/Rac 1/Nox 2信号通路的已知选择性抑制剂;这些研究的数据将通过使用该通路中关键信号蛋白的失活突变体和siRNA来确认。体外研究结果将在体内模型（stz诱导的糖尿病大鼠和小鼠，以及Zucker糖尿病肥胖大鼠）以及糖尿病视网膜病变人类供体的视网膜中进一步验证。我们期望证明Rac-1介导的Nox 2衍生的ROS作为视网膜病变发病机制中线粒体功能障碍的“引发剂”的作用。这将揭示新的治疗目标，以预防视网膜病变的早期发展阶段，并为患者提供额外的治疗手段，以预防/延缓这种威胁视力的糖尿病并发症。公共卫生相关性：糖尿病视网膜病变，一个缓慢的进展，是最常见的原因失明的年轻人。尽管有尖端的研究来探索这种疾病是如何发展的，但这种病变背后的实际分子和细胞机制仍然难以捉摸。该提案的重点是通过系统分析特定的信号通路Tiam 1-Rac 1-Nox 2来了解导致糖尿病视网膜病变发展的潜在损害机制，Tiam 1-Rac 1-Nox 2增加氧化应激并损害线粒体。我们将测试Nox 2衍生的ROS在线粒体功能障碍和糖尿病视网膜病变的发展中的“引发剂”作用。该申请代表了两个成熟实验室之间的多学科合作努力，这些实验室积极关注糖尿病视网膜病变发病机制中的G蛋白信号通路和线粒体功能障碍。本研究的数据预计将确定新的药物靶点，以阻止该盲法的进展。人类糖尿病中的疾病。