Dysregulated Adiponectin Transmembrane Signaling in Diabetic CoronaryVascular Injury and Heart Failure

随着治疗策略的广泛应用，心肌梗死（MI）患者的急性死亡率 已显着减少，但这些患者转向缺血性心肌病（IC）。重要的是， IC在糖尿病患者中要高得多，这是心血管疾病的主要危险因素。尽管取得了重大进展， 在心脏介入治疗中，糖尿病IC（DIC）的发病率和死亡率持续上升。人们日益认识 对于DIC，必须采取综合方法，而不是单纯关注心肌细胞， 预防/治疗。补充脂联素（APN），一种被鉴定为脂肪因子的蛋白质， 急性缺血心脏动物模型。然而，一些临床研究表明，APN水平升高 与慢性心力衰竭预后不良密切相关。我们和其他人以前报告说，APN功能是 在糖尿病动物和患者中显著减弱。我们最近的研究表明，糖尿病损害 心脏不仅对心肌细胞，在糖尿病导致冠状动脉内皮细胞（EC）受损， 微循环功能障碍显著增强心脏功能障碍。我们最近发表的工作和 初步实验进一步证明：1）在人糖尿病冠状动脉EC中，APN受体1敲除 （AdipoR 1，EC中的原型APN受体）mRNA表达不变，但AdipoR 1蛋白表达增加。 2）冠状动脉血管功能障碍（CVDy）在糖尿病动物中明显加重， 在2型糖尿病小鼠中，AdipoR 1在冠状动脉中的表达显著降低， EC. 3)蛋白质组学显示，AdipoR 1磷酸化是最重要的翻译后修饰， 糖尿病冠状动脉EC; 4）GRK 5（不是GRK 2），EC中的原型GRK家族成员，显著上调 GRK 5 OE对糖尿病冠状动脉EC中AdipoR 1 mRNA表达无影响。然而，在这方面， GRK 5 OE在很大程度上再现了人冠状动脉EC中APN/AdipoR 1相关的病理表型 6）相反，GRK 5 KO在糖尿病冠状动脉EC中恢复APN血管生成作用。基于这些 令人兴奋的初步结果，我们将测试一个新的假设，糖尿病GRK 5上调， AdipoR 1磷酸化在糖尿病CVDy中起致病作用，并导致有害的 DIC的后果GRK 5-AdipoR 1系统可能成为糖尿病CVDy治疗的新靶点， 最终改善DIC。这一假设将通过解决以下3个科学问题进行严格检验 问题：1）导致AdipoR 1脱敏和阻断AdipoR 1的分子机制是什么？ 糖尿病的功能？(Aim 1）; 2）当AdipoR 1被抑制时，APN的冠状血管保护作用如何受损？ 磷酸化？(Aim 2）和3）哪种干预措施在恢复冠状动脉血管功能方面最有效， 糖尿病心脏对抗DIC (Aim 3）。成功完成拟议的研究将大大促进我们的 从冠心病的整体调节认识糖尿病心脏损害的基础 微循环功能，并确定针对DIC的新的治疗靶点。

With extensive application of treatment strategies, the acute mortality of patients having myocardial infarct (MI) has significantly reduced but these patients turn to ischemic cardiomyopathy (IC). Importantly, the incidence of IC is much higher in diabetic patients, a major risk factor for cardiovascular disease. Despite the major advances in cardiac interventions, diabetic IC (DIC) morbidity and mortality continue to rise. It is increasingly recognized that integrative approaches, rather than purely focusing on cardiomyocytes, must be undertaken for DIC prevention/treatment. Supplementation of adiponectin (APN), a protein identified as an adipokine, protects the acute ischemic heart in animal model. However, several clinical studies demonstrate that elevated APN levels are strongly associated with poor prognosis of chronic HF. We and others previously report that APN function is markedly attenuated in diabetic animals and patients. Our most recent study demonstrates that diabetes injures heart not only on cardiomyocytes, the impaired coronary endothelial cells (EC) in diabetes leading to microcirculation dysfunction dramatically enhancing cardiac dysfunction. Our recently published work and preliminary experiments further demonstrate that 1) in human diabetic coronary EC, APN receptor 1 knockout (AdipoR1, prototypic APN receptor in EC) mRNA expression is unchanged, but AdipoR1 protein expression is significantly reduced; 2) coronary vascular dysfunction (CVDy) is markedly exaggerated in diabetic animals as well as in AdipoR1KO mice; in type 2 diabetic mice, AdipoR1 expression is significantly reduced in the coronary EC. 3) proteomics reveal that AdipoR1 phosphorylation is the most significant post-translational modification in diabetic coronary EC; 4) GRK5 (not GRK2), the prototypical GRK family member in EC, is markedly upregulated in diabetic coronary EC; 5) GRK5OE in coronary EC has no effect upon AdipoR1 mRNA expression. However, GRK5OE largely reproduces the pathologic phenotypes in human coronary EC concerning APN/AdipoR1 signaling; 6) conversely, GRK5KO restores APN angiogenic effect in diabetic coronary EC. Based upon these exciting preliminary results, we will test a novel hypothesis that diabetic GRK5 upregulation and resultant AdipoR1 phosphorylation plays causative roles in diabetic CVDy and contributes to the deleterious consequences of DIC. GRK5-AdipoR1 system may be a novel therapeutic target against diabetic CVDy, ultimately ameliorating the DIC. This hypothesis will be rigorously tested by addressing the following 3 scientific questions: 1) what is the molecular mechanism that causes AdipoR1 desensitization and blocks AdipoR1 function in diabetes? (Aim 1); 2) How is APN’s coronary vascular protective action impaired when AdipoR1 is phosphorylated? (Aim 2), and 3) which intervention is most effective in restoring coronary vascular function in the diabetic heart against DIC? (Aim 3). Successful completion of proposed studies will greatly advance our knowledge in understanding the basis of diabetic cardiac injury through integrating regulation of coronary microcirculatory function, and identify novel therapeutic targets against DIC.