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）：视网膜病仍然是糖尿病最令人恐惧的并发症之一。在糖尿病性视网膜病的发病机理中，超氧化物水平显着升高，线粒体功能失调，其DNA受损，导致超氧化物积累增加的恶性循环。新兴证据暗示了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，高血糖激活视网膜及其毛细血管细胞中的Rac1/NOX2信号轴，这表明线粒体失调表明NOX2激活代表了糖尿病诱导的线粒体功能障碍和细胞吞噬作用的早期事件。因此，我们的总体假设是，糖尿病中的NOX2衍生的ROS损害视网膜线粒体导致其功能障碍，毛细血管细胞的凋亡加速导致糖尿病性视网膜病的发展。我们建议通过解决在三个特定目标下提出的互补问题来进行有条理地检验这一假设。第一个目的将研究高血糖在视网膜中激活NOX2的机制，并将检验以下假设：在高血糖中，Rac1介导的NOX2激活和ROS产生启动线粒体损伤和细胞凋亡。由于视网膜病的严重程度与高脂血症直接相关，因此在第二个目的中，将研究脂肪毒性疾病促进糖尿病性视网膜病的发展的机制。我们的工作模型预测，脂肪毒性条件会促进Rac1介导的NOX2激活和ROS产生，从而引发线粒体损伤和细胞凋亡。第三个目标将确定NOX2调节对糖尿病性视网膜病的发展的影响，并将检验以下假设：NOX2的抑制作用会减弱线粒体损害并随后发展糖尿病性视网膜病。这些提出的研究基于使用有效的体外和体内模型系统之间的多学科协作工作生成的引人入胜的初步数据。我们建议利用TIAM1/RAC1/NOX2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非活性突变体和siRNA用于此途径中的关键信号蛋白来确认。体外发现将进一步验证体内模型（STZ诱导的糖尿病大鼠和小鼠，Zucker糖尿病脂肪大鼠），以及来自糖尿病性视网膜病的人类供体的视网膜中。我们期望证明RAC-1介导的NOX2衍生的ROS作为线粒体功能障碍的“引发剂”在视网膜病变的发病机理中的作用。这应该揭示用于预防视网膜病变的疗法的新靶标，并为患者提供其他治疗手段，以防止/阻止这种视力危及糖尿病并发症。公共卫生相关性：糖尿病性视网膜病，一个缓慢的进展，是年轻人最常见的失明原因。尽管有尖端的研究以探索疾病的发展方式，但这种病变的实际分子和细胞机制仍然难以捉摸。该提案的重点是理解负责通过对指定信号通路TiAM1-RAC1-NOX2的系统分析来发展糖尿病性视网膜病变的潜在破坏机制，从而增加了氧化应激并损坏了线粒体。我们将测试线粒体功能障碍中NOX2衍生的ROS的“引发剂”角色，以及糖尿病性视网膜病的发展。该应用代表了两个积极专注于G蛋白信号通路和线粒体功能障碍在糖尿病性视网膜病的发病机理中的多学科协作工作。这项研究的数据有望识别出停止这种盲人进展的新型药物靶标人类糖尿病中的疾病。