Ventricular Remodeling from H202 in Mechanical Overload

描述(由申请人提供)： 随着心肌肥厚的发展，左室血流动力学超负荷导致左室重构，最终往往发展为衰竭。在心力衰竭患者中，氧化应激增加，这表明可能与活性氧物种(ROS)有关。使用体外循环机械应变系统，模拟血流动力学超负荷时发生的更高的壁应力，我已经证明ROS在调节心肌重塑的两个关键特征-心肌细胞生长和凋亡-中发挥关键作用。介导机械应变对心肌细胞表型影响的ROS尚不清楚。有几条证据表明，过氧化氢(H_2O_2)起着核心作用。首先，我在体外通过在心肌细胞中过表达超氧化物歧化酶和过氧化氢酶获得的初步数据表明，过氧化氢，而不是超氧化物，既介导了心肌细胞的生长，也调节了心肌细胞的凋亡。第二，其他数据证实，直接应用H_2O_2可以引起体外培养的心肌细胞的生长和凋亡。最后，在衰竭的心脏中已经证明了更高水平的羟基自由基(.oh)，这是过氧化氢的分解产物。因此，我的主要假设是，由于血流动力学超负荷，H_2O_2在介导心肌重塑中起主要作用。该项目的目标是：1)确定过氧化氢在机械拉伸诱导的心肌细胞生长和凋亡中的作用；2)确定过氧化氢激活的信号通路和与之发生的直接氧化还原修饰；3)利用在体小鼠定位线粒体过氧化氢酶模型来评估压力超负荷的短期和慢性影响以及抗氧化剂的益处；以及4)使用蛋白质组学来评估可能调节蛋白质功能的直接蛋白质修饰。

DESCRIPTION (provided by applicant): Hemodynamic overload of the left ventricle results in LV remodeling with the development of myocardial hypertrophy that often progresses to failure. In patients with heart failure there is increased oxidative stress suggesting that reactive oxygen species (ROS) may be involved. Using an in vitro system of cyclic mechanical strain that simulates the higher wall stress that occurs with hemodynamic overload, I have shown ROS plays a critical role in mediating two key features of myocardial remodeling-myocyte growth and apoptosis. The ROS that mediate these effects of mechanical strain on cardiocyte phenotype is unknown. Several lines of evidence suggest that hydrogen peroxide (H2O2) plays a central role. First, my preliminary data obtained by overexpressing superoxide dismutase and catalase in cardiac myocytes in vitro suggests that H2O2, not superoxide, mediates both myocyte growth and apoptosis. Second, other data confirm that direct application of H2O2 can cause both growth and apoptosis of cardiac myocytes in vitro. Finally, higher levels of hydroxyl radical (.OH), a breakdown product of H2O2, have been demonstrated in failing heart. Thus, my primary hypothesis is that H2O2 plays a major role in mediating myocardial remodeling due to hemodynamic overload. The goals of this project are: 1) to define the role of hydrogen peroxide in mechanical stretch-induced myocyte growth and apoptosis; 2) to determine the signaling kinases that are activated by hydrogen peroxide and the direct redox modifications that occur with these; 3) to utilize in vivo mouse models of site directed mitochondrial catalase to evaluate the short and chronic effects of pressure overload and the benefits of antioxidants; and 4) the use of proteomics to evaluate the direct protein modifications that may regulate protein function.