Oxidative Stress, PKC Signaling and Heart Failure

 描述（由申请人提供）： 心力衰竭是退伍军人在退伍军人管理局医疗保健系统接受治疗的头号原因。在器官水平上测量的心力衰竭是由于心脏兴奋-收缩（E-C）偶联受损导致的细胞衰竭的结果。E-C偶联的一个关键结构成分是肌细胞横（T）小管系统。T-小管在膜兴奋、协调和同步激活肌浆网（SR）Ca 2+释放和肌肉收缩中起重要作用。在来自动物模型和人类患者的衰竭肌细胞中，我们和其他人已经表明，规则排列的T-小管系统经历破坏性重塑，导致细胞内Ca 2+释放异常和肌细胞收缩性受损。我们最近发表的数据有力地表明，T-小管结构的完整性是一个重要因素。 心肌收缩功能的关键结构决定因素。此外，我们发现， 嗜连接蛋白-2（JP 2）的蛋白表达是心脏病中T-小管变形的一个致病因素，JP 2是一种跨越T-小管和SR膜的结构蛋白。大量证据表明，E-C耦合受损的氧化应激，这是在心脏病心肌细胞升高。尽管氧化应激在心肌病中的作用明确，但人体抗氧化剂试验未能提供治疗益处，这表明对心脏病中氧化应激介导的途径的理解不完全，或者可能是以前临床试验中使用的错误抗氧化剂策略。以前的报道提供了坚实的证据表明，蛋白激酶C（PKC）被氧化应激激活。在细胞水平，PKC已被证明损害E-C偶联。在初步研究中，PKC的激活导致心肌细胞结构和功能的改变。然而，为了确定新的心脏病治疗策略，保持心肌收缩力，有一个关键的需要，以确定氧化应激PKC激活诱导E-C偶联功能障碍的机制。本申请的目的/目标是确定过度氧化应激、PKC信号传导与心力衰竭的发生和进展之间的机制联系。我们将结合联合收割机多学科的方法，包括原位共聚焦成像，电生理学，分子生物学，病理小鼠模型和新型转基因小鼠模型来验证我们的假设。我们的研究成果将推进我们的理解，并提供新的见解氧化应激介导的PKC激活和T-小管重塑的机制在心力衰竭病理生理学，并有望通过揭示心力衰竭治疗的新靶点产生重要的积极影响。鉴于在过去十年中，VA医疗保健系统中用于治疗心力衰竭的资源数量稳步增长，改善患者结局并降低心力衰竭相关护理成本的新治疗方法将为VA医疗保健系统提供显着益处。

 DESCRIPTION (provided by applicant): Heart failure is the number one reason for discharge for Veterans treated in VA health care system. Heart failure, measured at the organ level, is the result of cellular failure due to impairment of cardiac excitation-contraction (E-C) coupling. One key structural component of E-C coupling is the myocyte transverse (T)-tubule system. T-tubules play essential roles in membrane excitation, coordinated and synchronized activation of sarcoplasmic reticulum (SR) Ca2+ release, and muscle contraction. In failing myocytes from animal models and human patients, we and others have shown that the regularly arrayed T-tubule system undergoes disruptive remodeling, leading to aberrant intracellular Ca2+ release and compromised myocyte contractility. Our recently published data strongly suggest that T-tubule structural integrity is a critical structural determinant of myocardial contractile function. Moreover, we found that loss of protein expression of junctophilin-2 (JP2), a structural protein spanning T-tubules and the SR membrane, is a causative factor in T-tubule deformation in heart disease. Substantial evidence demonstrates that E-C coupling is impaired by oxidative stress, which is elevated in cardiomyocytes in heart disease. Despite the clear role for oxidative stress in cardiomyopathies, antioxidant trials in humans have failed to provide a therapeutic benefit, suggesting an incomplete understanding of oxidative stress-mediated pathways in heart disease or possibly wrong antioxidant strategy used in previous clinical trials. Previous reports have provided solid evidence that protein kinase C (PKC) is activated by oxidative stress. At the cellular level, PKC has been shown to impair E-C coupling. In pilot studies, activation of PKC resulted in alterations in cardiomyocyte structure and function. However, in order to identify new treatment strategies for heart disease that preserve cardiac contractility, there is a critical need to determine the mechanism by which PKC activation by oxidative stress induces E-C coupling dysfunction. The objective/goal of this application is to determine the mechanistic link between excessive oxidative stress, PKC signaling, and development and progression of heart failure. We will combine multidisciplinary approaches including in situ confocal imaging, electrophysiology, molecular biology, pathological mouse models and novel transgenic mouse models to test our hypothesis. Accomplishment of our studies will advance our understanding and provide new insights into the mechanisms of oxidative stress-mediated PKC activation and T-tubule remodeling in heart failure pathophysiology and is expected to have an important positive impact by revealing new targets for heart failure therapeutics. Given that over the last decade the number of resources used to treat heart failure within the VA health care system has grown steadily, new treatments that both improve patient outcomes and reduce the cost of care associated with heart failure will provide significant benefit to the VA health care system.