Investigation of the mechanisms regulating endothelial insulin transport

项目摘要/摘要 胰岛素抵抗(IR)是一种代谢紊乱状态，出现在II型糖尿病(T2D)和 心血管疾病。胰岛素抵抗的特点是胰岛素促进血糖的能力受损。 处理成胰岛素敏感组织，其中大部分是骨骼肌(SKM)。在胰岛素可以 刺激肌肉葡萄糖摄取(MGU)，它必须首先从血浆中物理运输，通过 持续的SKM毛细血管内皮细胞，进入沐浴心肌细胞的间质液体中。事实上，这种能力 刺激MGU的胰岛素浓度取决于胰岛素穿过毛细血管内皮细胞的速率。 此外，来自我们实验室和其他实验室的初步数据表明，胰岛素通过 胰岛素抵抗状态下血管内皮细胞受损。尽管胰岛素转运到胰岛素的重要性 作用、内皮胰岛素转运机制及其在体内的长期调节作用较差 明白了。这项提案将集中在两个具体目标上，以定义调节胰岛素的机制 体内转运。这些特定的目标将检验以下假设：(1)内皮细胞胰岛素转运是一种活跃的 需要空泡小泡和胰岛素受体的过程以及(2)肥胖导致的胰岛素缺陷 运输是通过运动训练通过一氧化氮(NO)依赖的机制来拯救的。研究胰岛素 体内转运，我开发了一种高度创新的成像技术来测量毛细血管对 活体小鼠体内的胰岛素荧光探针。这项技术将与有条件的、内皮细胞特异性的 对小鼠进行基因修饰以描述胰岛素受体小窝蛋白-1和一氧化氮对胰岛素的作用 运输。这些手法对SKM胰岛素敏感性的影响将使用以下方法进行评估 用同位素葡萄糖示踪剂在清醒的非应激小鼠中进行高胰岛素-正常血糖钳夹试验。这个 拟议的研究将阐明胰岛素转运被敏锐地调节和响应的机制。 对慢性刺激(肥胖和运动)的影响。这些研究的结果将改善发展的前景。 在T2D的治疗中，针对血管系统和SKM胰岛素输送的治疗策略。

PROJECT SUMMARY/ABSTRACT Insulin resistance (IR) is a state of metabolic dysfunction that precedes Type II diabetes (T2D) and cardiovascular disease. IR is characterized by an impaired ability of insulin to promote plasma glucose disposal into insulin-sensitive tissue, the majority of which is skeletal muscle (SkM). Before insulin can stimulate muscle glucose uptake (MGU), it must first be physically transported from the plasma, across the continuous endothelium of SkM capillaries and into the interstitial fluid that bathes myocytes. In fact, the ability of insulin to stimulate MGU depends on the rate at which insulin crosses the capillary endothelium. Furthermore, preliminary data from our laboratory and others have demonstrated that insulin transport across the endothelium is impaired in the insulin resistant state. Despite the importance of insulin transport to insulin action, the mechanism of endothelial insulin transport and its long-term regulation in vivo are poorly understood. This proposal will focus on two Specific Aims to define the mechanisms that regulate insulin transport in vivo. These Specific Aims will test the hypotheses that (1) endothelial insulin transport is an active process that requires caveolar vesicles and the insulin receptor and (2) obesity-induced defects in insulin transport are rescued by exercise training through a nitric oxide(NO)-dependent mechanism. To study insulin transport in vivo, I have developed a highly innovative imaging technique to measure capillary permeability to a fluorescent insulin probe in live mice. This technique will be combined with conditional, endothelial-specific genetic modifications in mice to delineate the role of caveolin-1, the insulin receptor, and NO to insulin transport. The effects of these manipulations on SkM insulin sensitivity will be assessed using hyperinsulinemic-euglycemic clamps with isotopic glucose tracers in conscious, unstressed mice. The proposed studies will elucidate the mechanisms by which insulin transport is regulated acutely and in response to chronic stimuli (obesity and exercise). The results of these studies will improve the prospect of developing therapeutic strategies that target the vasculature and SkM insulin delivery in the treatment of T2D.