Vascular complications of type 2 diabetes: tyrosine phosphorylation of the endothelial nitric oxide synthase (eNOS)

高达80%的糖尿病患者死亡是由于相关的心血管并发症。内皮功能障碍是疾病发展的早期事件，其特征是内皮源性一氧化氮（NO）的产生减少。这不仅会影响血管张力和体内平衡，还会导致来自骨髓的祖细胞的动员受损。内皮NO合成酶（eNOS）的活性受Ca2+依赖性和非依赖性过程的调节；尤其是通过磷酸化的翻译后修饰。我们最近在eNOS中发现了一个新的调节酪氨酸残基（Tyr657），它可以降低酶的活性，并将这一事件与氧化还原和胰岛素敏感的酪氨酸激酶Pyk2的激活联系起来。该提案旨在确定Pyk2激活和eNOS Tyr657磷酸化在糖尿病相关血管病变中的作用程度。此外，由于eNOS决定了循环祖细胞的恢复能力以及它们从骨髓生态位的动员，我们计划评估Pyk2和酪氨酸磷酸酶在调节健康和糖尿病祖细胞的血管生成潜力以及这些细胞从骨髓的动员中的作用，再次在控制和糖尿病条件下。对动物模型的研究将辅以从健康和糖尿病患者身上分离的人类细胞的研究。该项目的组织充分利用了两个地点的专业知识，并通过两个小组的密切合作产生了明显的协同效应。

Up to 80% of deaths in patients with diabetes are due to the associated cardiovascular complications. Endothelial dysfunction is an early event in disease development and is characterised by the decreased production of endothelium-derived nitric oxide (NO). This not only affects vascular tone and homeostasis but also results in the impaired mobilization of progenitor cells from the bone marrow. The activity of the endothelial NO synthase (eNOS) is regulated by Ca2+-dependent and –independent processes; particularly by its posttranslational modification by phosphorylation. We have recently identified a novel regulatory tyrosine residue within eNOS (Tyr657) that attenuates enzyme activity and linked this event with the activation of the redox- and insulin-sensitive tyrosine kinase, Pyk2. This proposal aims to determine the extent to which Pyk2 activation and eNOS Tyr657 phosphorylation underlies the vasculopathy associated with diabetes. Moreover as eNOS determines the restorative capacity of circulating progenitor cells as well as their mobilization from the bone marrow niche, we plan to assess the role of Pyk2 and tyrosine phosphatases in regulating the angiogenic potential of healthy and diabetic progenitor cells as well as the mobilization of these cells from the bone marrow, again under control and diabetic conditions. Studies in animal models will be complemented by studies on human cells isolated from healthy and diabetic patients. The organisation of the project makes optimal use of the expertise available at the two locations and there is a clear synergy expected by the close collaboration of the two groups.