Investigation of the mechanisms regulating endothelial insulin transport

项目总结/摘要 胰岛素抵抗（IR）是先于II型糖尿病（T2 D）的代谢功能障碍的状态， 心血管疾病IR的特征是胰岛素促进血糖的能力受损 处置到胰岛素敏感组织，其中大部分是骨骼肌（SkM）。在胰岛素能够 为了刺激肌肉葡萄糖摄取（MGU），它必须首先从血浆中物理转运，穿过 血管内皮细胞的连续内皮细胞，并进入浸润肌细胞的间质液。事实上， 胰岛素刺激MGU的速率取决于胰岛素穿过毛细血管内皮的速率。 此外，来自我们实验室和其他实验室的初步数据表明，胰岛素跨膜转运 内皮在胰岛素抵抗状态下受损。尽管胰岛素转运对胰岛素的重要性 作用，内皮细胞胰岛素转运机制及其在体内的长期调节是很差的 明白该提案将集中于两个特定目的，以确定调节胰岛素的机制 体内运输这些特定目的将检验以下假设：（1）内皮胰岛素转运是一种主动的 需要小囊泡和胰岛素受体的过程和（2）肥胖诱导的胰岛素缺陷 运动训练通过一氧化氮（NO）依赖性机制来挽救运输。研究胰岛素 在体内运输，我已经开发了一种高度创新的成像技术，以测量毛细血管通透性， 荧光胰岛素探针。该技术将与条件性内皮特异性 在小鼠中进行遗传修饰，以描述小窝蛋白-1、胰岛素受体和NO对胰岛素的作用 运输这些操作对SkM胰岛素敏感性的影响将通过使用 高胰岛素-正常血糖钳夹与同位素葡萄糖示踪剂在清醒，无应激小鼠。的 建议的研究将阐明胰岛素转运的机制， 慢性刺激（肥胖和运动）。这些研究成果将为进一步开发利用生物柴油提供良好的前景 在T2 D治疗中靶向血管系统和SkM胰岛素递送的治疗策略。

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.