Glucose transport in the diabetic outer retina.

糖尿病外视网膜中的葡萄糖转运。

• 批准号: 9487896
• 负责人: Ivy S Samuels
• 金额: --
• 依托单位: LOUIS STOKES CLEVELAND VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-10-01 至 2019-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9487896
• 关键词: AIDS therapy; Abate; Adult; Affect; Background Diabetic Retinopathy; Binding; Blindness; Blood; Blood Glucose; Blood-Retinal Barrier; Cell Culture Techniques; Cells; Clinical; Clinical Trials; Defect; Development; Diabetes Mellitus; Diabetes prevention; Diabetic Retinopathy; Diabetic mouse; Diffusion; Disease; Electron Microscopy; Electroretinography; Event; Eye; Functional disorder; Generations; Genes; Glucose; Glucose Transporter; Goals; Hyperglycemia; Hyperglycemic Mice; Image; In Vitro; Insulin; Insulin Receptor; Insulin-Dependent Diabetes Mellitus; Laboratories; Leukostasis; Measures; Mediating; Membrane; Methods; Modeling; Molecular; Mus; Pathology; Patients; Phase; Photoreceptors; Play; Prevention; Preventive therapy; Reagent; Receptor Signaling; Regulation; Research; Resources; Retina; Retinal; Retinal Diseases; Risk Factors; Role; SLC2A1 gene; Serum; Severities; Signal Transduction; Structure of retinal pigment epithelium; Superoxides; Symptoms; Techniques; Testing; Therapeutic Intervention; Time; United States; Veterans; Vision; Work; aged; apical membrane; basolateral membrane; blood glucose regulation; blood lead; diabetes risk; diabetic; early detection biomarkers; experimental study; glucose analog; glucose monitor; glucose transport; glycemic control; in vivo; innovation; insulin signaling; microvascular pathology; mouse model; novel; novel therapeutics; prevent; public health relevance; success; targeted treatment; ubiquitin-protein ligase

 DESCRIPTION (provided by applicant): Hyperglycemia is the major risk factor for development of diabetic retinopathy. Tight control of serum glucose levels is currently viewed as the primary means to slow progression to retinopathy, but the mechanisms by which glucose enters the retina and how they become perturbed in diabetes remains unclear. Therefore, understanding the mechanism of how hyperglycemia affects the outer retina (RPE and photoreceptors) and identifying methods to ameliorate glucose-induced outer retina dysfunction and early biomarkers of diabetic retinopathy is important. Recently, it has been shown that systemic reduction of the facilitative diffusion glucose transporter, GLUT1 will reduce glucose levels in the retina; however, these studies do not provide a mechanism or means to control glucose entry specifically to the retina via the blood retinal barrier (BRB). The first objective of this proposal is to determine if reductions in GLUT1 within the RPE leads to reduced retinal glucose accumulation within the RPE/outer retina, prevention of RPE dysfunction and early biomarkers of diabetic retinopathy in mouse models of diabetes. The second objective is to investigate mechanisms of GLUT1 modulation by insulin and to determine if abrogation of insulin signal transduction in the RPE can mitigate abnormal RPE function in mouse models of diabetes by regulation of GLUT1 expression and localization. We hypothesize that (1) hyperglycemia-induced increases in the expression and redistribution of GLUT1 in the RPE mediates diabetes-associated reductions in RPE/outer retina function and early signs of retinopathy, (2) that insulin also modulates glucose transport by GLUT1 in the RPE and (3) that blockade of insulin signaling in the RPE will exacerbate retinal pathophysiology found in a mouse model of diabetes. To test these hypotheses, a mouse model of type 1 diabetes will be employed to investigate GLUT1 expression and distribution within the apical and basolateral membranes of the RPE and determine if this is concomitant with an accumulation of intracellular glucose. To determine if reductions in GLUT1 expression prevents outer retina dysfunction, a haploinsufficient Glut1+/- mouse and mice in which the Glut1 gene is specifically inactivated only within the RPE will be utilized. To additionally assess how insulin affects GLUT1-mediated glucose entry and accumulation in the retina, conditional inactivation the insulin receptor (IR) will be employed to abrogate downstream signaling from this receptor. In vitro analysis of cultured RPE cells will also be used to determine if insulin treatment alters glucose transport through regulation of GLUT1 by affecting its association with a binding partner, GIPC and/or the E3 ubiquitin ligase, Nedd4-2. These experiments will determine the role that GLUT1 plays in outer retina dysfunction as a result of hyperglycemia, elucidate how insulin is involved in GLUT1 modulation, and identify a mechanism which can be targeted for therapeutic intervention.

 描述（由申请人提供）： 高血糖是糖尿病视网膜病变发生的主要危险因素，目前认为严格控制血糖水平是减缓视网膜病变进展的主要手段，但葡萄糖进入视网膜的机制以及它们在糖尿病中如何受到干扰仍不清楚。因此，了解高血糖影响外视网膜（RPE 和光感受器）的机制，并确定改善葡萄糖引起的外视网膜功能障碍和糖尿病视网膜病变早期生物标志物的方法最近，有研究表明，系统性减少促进扩散葡萄糖转运蛋白 GLUT1 会降低视网膜中的葡萄糖水平；然而，这些研究并未提供控制葡萄糖通过血液进入视网膜的机制或方法。该提案的第一个目标是确定 RPE 内 GLUT1 的减少是否会导致 RPE/外视网膜内视网膜葡萄糖积累减少，预防 RPE 功能障碍和早期生物标志物。第二个目标是研究胰岛素调节 GLUT1 的机制，并确定取消 RPE 中的胰岛素信号转导是否可以通过调节 GLUT1 表达和定位来减轻糖尿病小鼠模型中的异常 RPE 功能。我们发现 (1) 高血糖诱导的 RPE 中 GLUT1 表达和重新分布的增加介导了糖尿病相关的 RPE/外视网膜功能和早期体征的降低(2) 胰岛素还通过 RPE 中的 GLUT1 调节葡萄糖转运；(3) 阻断 RPE 中的胰岛素信号将加剧糖尿病小鼠模型中发现的视网膜病理生理学。 1 型糖尿病将用于研究 RPE 顶膜和基底外侧膜内的 GLUT1 表达和分布，并确定这是否伴随细胞内葡萄糖的积累。 GLUT1 表达的减少可防止外视网膜功能障碍，将利用单倍体 Glut1+/- 小鼠和仅在 RPE 内特异性失活 Glut1 基因的小鼠来进一步评估胰岛素如何影响 GLUT1 介导的葡萄糖进入和积累在视网膜中。胰岛素受体 (IR) 的条件失活将用于消除该受体的下游信号传导，也将用于培养 RPE 细胞的体外分析来确定是否进行胰岛素治疗。通过与结合伴侣 GIPC 和/或 E3 泛素连接酶 Nedd4-2 的结合来调节 GLUT1 来改变葡萄糖转运。这些实验将确定 GLUT1 在影响高血糖导致的外视网膜功能障碍中所起的作用，并阐明如何发挥作用。胰岛素参与 GLUT1 调节，并确定了一种可作为治疗干预目标的机制。