Glucose transport in the diabetic outer retina.

糖尿病外视网膜中的葡萄糖转运。

• 批准号: 9032589
• 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/9032589
• 关键词: Abate; Adult; Affect; Background Diabetic Retinopathy; Binding; Biological Markers; 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; Staging; Structure of retinal pigment epithelium; Superoxides; Symptoms; Techniques; Testing; Therapeutic Intervention; Time; United States; Veterans; Vision; Work; aged; apical membrane; base; basolateral membrane; blood glucose regulation; diabetes risk; diabetic; glucose analog; glucose monitor; glucose transport; glycemic control; in vivo; innovation; insulin signaling; microvascular pathology; mouse model; novel; novel therapeutics; prevent; public health relevance; research study; success; targeted treatment; ubiquitin-protein ligase; whole blood lead

 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，严格控制血糖水平被认为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，了解高血糖如何影响外视网膜（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非常重要。最近，研究表明，系统性减少易化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视网膜屏障（BRB）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 功能障碍以及糖尿病小鼠模型中糖尿病视网膜病变的早期生物标志物。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异常的 RPE 功能。我们假设（1）高血糖诱导的 RPE 中 GLUT1 表达和重新分布的增加介导与糖尿病相关的 RPE/外视网膜功能降低和视网膜病变的早期症状，（2）胰岛素还通过 RPE 中的 GLUT1 调节葡萄糖转运，（3）RPE 中胰岛素信号传导的阻断将导致视网膜病变的早期症状。 加剧糖尿病小鼠模型中发现的视网膜病理生理学。为了检验这些假设，将采用 1 型糖尿病小鼠模型来研究 RPE 顶膜和基底外侧膜内 GLUT1 的表达和分布，并确定这是否伴随细胞内葡萄糖的积累。为了确定 GLUT1 表达的减少是否可以防止外视网膜功能障碍，将使用单倍体不足的 Glut1+/- 小鼠和仅在 RPE 内特异性灭活 Glut1 基因的小鼠。为了进一步评估胰岛素如何影响 GLUT1 介导的葡萄糖进入和在视网膜中的积累，将利用胰岛素受体 (IR) 的条件失活来消除该受体的下游信号传导。培养的 RPE 细胞的体外分析也将用于确定胰岛素治疗是否通过影响 GLUT1 与结合伴侣 GIPC 和/或 E3 泛素连接酶 Nedd4-2 的关联来调节 GLUT1，从而改变葡萄糖转运。这些实验将确定 GLUT1 在高血糖导致的外视网膜功能障碍中所起的作用，阐明胰岛素如何参与 GLUT1 调节，并确定可用于治疗干预的机制。