Insulin-VEGF Signaling Crosstalk in Endothelial Cells

描述(由申请人提供)：据估计，美国有1820万人患有糖尿病。1型和2型糖尿病的血管并发症，包括视网膜病变、外周动脉病变和动脉粥样硬化，是糖尿病患者发病率和死亡率的主要贡献者。糖尿病患者的血管内皮细胞长期暴露在高浓度的葡萄糖和晚期糖基化终末产物(AGE)中，导致“内皮功能障碍”，其特征是血管通透性、反应性、血栓形成和血管修复改变。胰岛素和血管内皮生长因子在调节血管内皮细胞存活和内皮依赖性血管松弛中都起着重要作用，在糖尿病中这两种信号分子的功能都受到了损害。鉴于胰岛素和血管内皮细胞生长因子激活的信号通路的明显重叠，拟议的研究将检验这一假说，即在与糖尿病相关的条件下，内皮细胞中这些通路之间的干扰串扰有助于内皮功能障碍的发展。具体地说，这些研究旨在确定血管内皮生长因子刺激对内皮细胞胰岛素反应性的影响，使用人内皮细胞培养来测量胰岛素刺激的信号蛋白磷酸化、一氧化氮产生和增殖/存活。此外，我们将通过测量暴露于高浓度葡萄糖或AGE的内皮细胞培养中的血管内皮生长因子信号成分、一氧化氮产生和有丝分裂来确定与糖尿病状态或胰岛素抵抗相关的条件是否影响血管内皮细胞对血管内皮生长因子的反应。我们还将使用具有已知胰岛素信号缺陷的新型小鼠胚胎干细胞株来评估血管内皮生长因子刺激的内皮祖细胞分化。针对血管内皮生长因子信号转导元件(抗血管内皮生长因子抗体、蛋白激酶C-β抑制剂)的实验疗法目前正在进行糖尿病视网膜病变的临床试验。识别先前未知的胰岛素和血管内皮生长因子信号之间的交叉点可能揭示在血管内皮细胞或其他胰岛素敏感组织中克服胰岛素抵抗的干预靶点。这些信息反过来应有助于合理开发治疗糖尿病血管并发症的新的选择性疗法。

DESCRIPTION (provided by applicant): Diabetes mellitus afflicts an estimated 18.2 million individuals in the US. Vascular complications of Types 1 and 2 diabetes, including retinopathies, peripheral artery disease, and atherosclerosis, are major contributors to morbidity and mortality in diabetic patients. The vascular endothelium in diabetes is chronically exposed to high concentrations of glucose and advanced glycation end-products (AGE), resulting in "endothelial dysfunction," a condition characterized by altered vascular permeability, reactivity, thrombogenesis and vessel repair. Insulin and vascular endothelial growth factor (VEGF) each have important roles in regulating endothelial cell survival and endothelium-dependent vasorelaxation, and the functions of both signaling agents are compromised in diabetes. In view of the apparent overlap in signaling pathways activated by insulin and VEGF, the proposed studies will test the hypothesis that perturbed crosstalk among these pathways in endothelial cells contributes to the development of endothelial dysfunction under conditions associated with diabetes mellitus. Specifically, these studies aim to determine the effects of VEGF stimulation on endothelial responsiveness to insulin, using human endothelial cell cultures to measure insulin-stimulated signaling protein phosphorylation, nitric oxide production and proliferation/survival. In addition, we will determine whether conditions associated with the diabetic state or insulin resistance affect endothelial responsiveness to VEGF, by measuring VEGF signaling components, nitric oxide production and mitogenesis in endothelial cell cultures exposed to elevated concentrations of glucose or AGE. We also will assess VEGF-stimulated endothelial progenitor differentiation using novel mouse embryonic stem cell lines bearing known defects in insulin signaling. Experimental therapeutics that target elements of VEGF signaling (anti-VEGF antibodies, protein kinase C-beta inhibitors) currently are undergoing clinical trials in diabetic retinopathies. The identification of previously unrecognized points of crosstalk between insulin and VEGF signaling may reveal targets of intervention to overcome resistance to insulin action in the endothelium or other insulin-sensitive tissues. This information, in turn, should facilitate the rational development of new, selective therapeutics for the vascular complications of diabetes.