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 已显著减少，但这些患者转为缺血性心肌病(IC)。重要的是，该病的发病率 糖尿病患者的IC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 在心脏干预方面，糖尿病IC(DIC)的发病率和死亡率持续上升。越来越多的人认识到 对于DIC，必须采取综合治疗方法，而不是单纯关注心肌细胞 预防/治疗。补充脂联素(APN)，一种被确认为脂肪因子的蛋白质，可以保护 急性心肌缺血动物模型。然而，一些临床研究表明，APN水平升高 与慢性心衰预后不良密切相关。我们和其他人之前报告说，APN功能是 在糖尿病动物和患者中显著减弱。我们最新的研究表明，糖尿病会损害 心脏不仅依赖于心肌细胞，糖尿病患者冠状动脉内皮细胞(EC)受损可导致 微循环障碍极大地加剧了心脏功能障碍。我们最近出版的作品和 初步实验进一步证明：1)在人糖尿病冠脉内皮细胞中，APN受体1基因被敲除 (AdipoR1，EC中的原型APN受体)mRNA的表达没有变化，但AdipoR1的蛋白表达 显著降低；2)冠状动脉血管功能障碍(CVDy)在糖尿病动物中明显夸大 在2型糖尿病小鼠中，冠状动脉中AdipoR1的表达显著降低 欧共体。3)蛋白质组学显示，AdipoR1的磷酸化是最重要的翻译后修饰 糖尿病冠脉EC；4)EC中典型的GRK家族成员GRK5(不是GRK2)明显上调 5)冠脉内皮细胞中GRK5OE对AdipoR1mRNA表达无影响。然而， GRK50E在很大程度上复制了人冠状动脉内皮细胞APN/AdipoR1的病理表型 6)相反，GRK5KO可恢复糖尿病冠脉内皮细胞的APN血管生成作用。基于这些 令人振奋的初步结果，我们将测试一个新的假设，糖尿病GRK5上调和结果 AdipoR1的磷酸化在糖尿病的CVDy中起致病作用并促进有害的 DIC的后果。GRK5-AdipoR1系统可能成为治疗糖尿病CVDy的新靶点， 最终改善DIC。这一假设将通过解决以下3个科学问题得到严格检验 问题：1)导致AdipoR1脱敏并阻断AdipoR1的分子机制是什么 糖尿病的功能？(目标1)；2)当AdipoR1降低时，APN的冠状动脉血管保护作用如何受损 被磷酸化了？(目标2)，以及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？(目标3)。成功完成拟议的研究将极大地促进我们的 从冠脉综合调节认识糖尿病心脏损害的基础 微循环功能，并寻找治疗DIC的新靶点。

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.