Role of Ras in Retinal Cell Death in Diabetes

Ras 在糖尿病视网膜细胞死亡中的作用

• 批准号: 7924550
• 负责人: RENU A. KOWLURU
• 金额: $ 36.64万
• 依托单位: WAYNE STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7924550
• 关键词: Animal Model; Apoptosis; Biological Process; Blindness; Blood capillaries; Cell Death; Cells; Characteristics; Chemicals; Complications of Diabetes Mellitus; Data; Development; Diabetes Mellitus; Diabetic Retinopathy; Disease; Endothelial Cells; Extracellular Matrix; Failure; Family member; Fright; Funding; Future; GTP-Binding Proteins; Gelatinase B; Genes; Genetic; Glucose; HRAS gene; Histopathology; Hyperglycemia; In Vitro; Inflammation; Inflammation Mediators; Inhibition of Matrix Metalloproteinases Pathway; Institutes; Intervention; Matrix Metalloproteinases; Measures; Mediating; Mediator of activation protein; Memory; Metabolic; Metalloproteases; Mitochondria; Modeling; Molecular Target; Molecular Weight; Mus; NF-kappa B; Oxidative Stress; Pathogenesis; Pathway interactions; Patients; Permeability; Plague; Process; Rat-1; Rattus; Reporting; Retina; Retinal; Retinal Diseases; Role; Signal Transduction; Superoxides; System; Testing; Therapeutic; Thioctic Acid; Vision; antioxidant therapy; base; capillary; caspase-3; design; diabetic patient; diabetic rat; genetic manipulation; glycemic control; in vivo; inhibitor/antagonist; insight; member; mitochondrial dysfunction; novel; prevent; public health relevance; raf-1 Protein; research study; retinal apoptosis; young adult

DESCRIPTION (provided by applicant): Retinopathy is one of the most prevalent and feared complications of diabetes. Although hyperglycemia is considered as the major cause of its development, the exact mechanism remains unclear. The overall aim of this proposal is to elucidate new insight into the pathogenesis of diabetic retinopathy. During the previous funding period we have demonstrated an important and novel role for a small molecular weight G- protein, H-Ras, in the accelerated apoptosis of retinal capillary cells. H-Ras is reported to upregulate matrix metalloproteinases-9 (MMP-9), a member of the family of metalloproteinases that regulate major biological functions, including apoptosis, inflammation and matrix degradation. Our central hypothesis is that 'activation of H-Ras cascade activates MMP-9, accelerating apoptosis of retinal capillary cells, and this ultimately leads to the development of retinopathy in diabetes'. In support, our exciting preliminary data show that MMP-9 is activated in the retina in diabetes. Inhibitors of H-Ras function prevent glucose-induced activation of MMP-9 in retinal capillary cells, and specific inhibitors of MMP-9 ameliorate increases in proinflammatory mediators and apoptosis. Aim 1 will determine the mechanism by which MMP-9 is activated in retinal microvasculature in diabetes. Using isolated retinal capillary cells and animal models of diabetic retinopathy, we will test the hypothesis that MMP-9 is activated in diabetes via H-Ras mediated signaling cascade, Raf-1-MAPK-ERK-NF-kB. Aim 2 will investigate the mechanism by which activated MMP-9 results in the development of diabetic retinopathy; and the hypothesis predicts that the activation of MMP-9 (a) damages mitochondria provoking apoptosis of retinal microvascular cells, and (b) increases inflammation and permeability, resulting in the development of retinopathy. This hypothesis will be tested in both in vitro and in vivo systems by pharmacologically or genetically manipulating MMP-9 gene. Studies have shown that diabetic retinopathy continues to progress for sometime after good glycemic control is re-instituted, suggesting a metabolic memory phenomenon. In aim 3, using a rat model, we will test the hypothesis that 'due to the continued activation of H-Ras after reversal of hyperglycemia, MMP-9 remains activated with elevated inflammatory mediators and continued capillary cell apoptosis. This is supported by our preliminary data showing the failure of retinal H-Ras activation to halt after re-establishment of normal glucose in diabetic rats. Understanding the signal transduction mechanisms responsible for the pathogenesis of diabetic retinopathy by characterizing the role of MMP-9 in the retina capillary cell death will provide fresh insight into the novel molecular targets for future pharmacological interventions to inhibit this sight-threatening complication of diabetes. This should help design specific therapeutics (e.g. inhibitors of MMP-9 and antisense) for future pharmacological interventions which patients can use to supplement their best possible glycemic control to treat this sight-threatening complication of diabetes. PUBLIC HEALTH RELEVANCE: This proposal is aimed at understanding the putative regulatory role(s) of matrix metalloproteinases in glucose-induced alterations in metabolic functions of retinal capillary cells leading to their demise, and the development of diabetic retinopathy. The results are expected to elucidate new insight into the pathogenesis of diabetic retinopathy, and reveal novel targets for therapies to prevent the development and progression of retinopathy.

描述（由申请人提供）：视网膜病变是糖尿病最常见和最令人担心的并发症之一。尽管高血糖被认为是其发生的主要原因，但确切的机制仍不清楚。该提案的总体目标是阐明对糖尿病视网膜病变发病机制的新见解。在之前的资助期间，我们已经证明了小分子量 G 蛋白 H-Ras 在加速视网膜毛细血管细胞凋亡中的重要而新颖的作用。据报道，H-Ras 可以上调基质金属蛋白酶 9 (MMP-9)，这是金属蛋白酶家族的一员，可调节主要生物功能，包括细胞凋亡、炎症和基质降解。我们的中心假设是“H-Ras 级联的激活会激活 MMP-9，加速视网膜毛细血管细胞的凋亡，最终导致糖尿病视网膜病变的发展”。作为支持，我们令人兴奋的初步数据表明 MMP-9 在糖尿病患者的视网膜中被激活。 H-Ras 功能抑制剂可防止葡萄糖诱导的视网膜毛细血管细胞中 MMP-9 的激活，而 MMP-9 的特异性抑制剂可改善促炎介质和细胞凋亡的增加。目标 1 将确定糖尿病视网膜微血管系统中 MMP-9 的激活机制。使用分离的视网膜毛细血管细胞和糖尿病视网膜病变的动物模型，我们将测试 MMP-9 在糖尿病中通过 H-Ras 介导的信号级联反应 Raf-1-MAPK-ERK-NF-kB 激活的假设。目标 2 将研究激活的 MMP-9 导致糖尿病视网膜病变发生的机制；该假说预测，MMP-9 的激活 (a) 会损害线粒体，引发视网膜微血管细胞凋亡，(b) 会增加炎症和通透性，导致视网膜病变的发生。该假设将通过药理学或基因操作 MMP-9 基因在体外和体内系统中得到检验。研究表明，在重新进行良好的血糖控制后，糖尿病视网膜病变会持续进展一段时间，这表明存在代谢记忆现象。在目标 3 中，我们将使用大鼠模型来检验以下假设：“由于高血糖逆转后 H-Ras 持续激活，MMP-9 在炎症介质升高和毛细血管细胞持续凋亡的情况下保持激活状态。”我们的初步数据支持了这一点，显示糖尿病大鼠的血糖恢复正常后，视网膜 H-Ras 激活未能停止。通过表征 MMP-9 在视网膜毛细血管细胞死亡中的作用来了解导致糖尿病视网膜病变发病机制的信号转导机制，将为未来抑制这种威胁视力的糖尿病并发症的药物干预的新分子靶标提供新的见解。这应该有助于为未来的药物干预设计特定的治疗药物（例如 MMP-9 和反义抑制剂），患者可以使用这些药物来补充最佳的血糖控制，以治疗这种威胁视力的糖尿病并发症。 公共健康相关性：本提案旨在了解基质金属蛋白酶在葡萄糖诱导的视网膜毛细血管细胞代谢功能改变（导致其死亡）和糖尿病视网膜病变发展中的假定调节作用。研究结果有望阐明糖尿病视网膜病变发病机制的新见解，并揭示预防视网膜病变发生和进展的治疗新靶点。