MYOCYTE APOPTOSIS AND A TRANSGENIC HEART FAILURE MODEL

充血性心力衰竭是心脏病发病率和死亡率的主要原因， 美国的 我们对这种机制知之甚少， 特定的病原体可引起突然或逐渐发作， 心室功能障碍 为了确定可能 会导致心室功能恶化 产生了靶向表达非- 感染性柯萨奇病毒cDNA到心室。 初步数据 表明这种独特的转基因模型具有许多特征， 心肌病，包括收缩和舒张功能障碍，心肌 纤维化和基因表达的胚胎程序的诱导。 我们还发现柯萨奇B3病毒可以感染小鼠和大鼠 培养物中的肌细胞，并可诱导细胞病变效应，包括 心肌细胞凋亡 使用细胞培养的综合方法 与转基因动物模型相结合， 确定的刺激可对心肌细胞产生不利影响的机制 细胞培养物和心肌病的完整动物模型。 在细胞培养中，我们建议评估特定的机制， 柯萨奇病毒蛋白可诱导细胞凋亡和肌丝破坏。 在细胞培养中的发现的功能意义将是 在转基因小鼠中进行评估。这些实验是基于 以下假设：1）特定的柯萨奇病毒蛋白，如 蛋白酶2A诱导细胞凋亡和肌丝断裂 心肌细胞，和2）低水平CVB心脏特异性表达 转基因小鼠心肌细胞中的蛋白质可以诱导 与心室功能障碍相关的兴奋收缩偶联。 因此，提出了以下具体目标：1）确定 CVB蛋白酶2A是否足以诱导病毒介导的 培养新生大鼠心肌细胞凋亡和肌丝断裂 心室肌细胞，2）确定CVB 3诱导 在成年心室肌细胞中的直接细胞病变效应，3）检查 心脏特异性表达血流动力学和功能意义 非感染性CVB cDNA在转基因小鼠中的表达，以及4）确定是否 复制缺陷型CVB 3基因组的心脏表达导致 与兴奋相关的异常心室功能 收缩偶联异常和收缩力改变， 分离的心室肌细胞。 这些实验将有助于我们 了解心室功能 随着特定蛋白质的表达而恶化， 心肌病

Congestive heart failure is a major cause of morbidity and mortality in the United States. Little is known about the mechanisms by which specific etiologic agents can induce the sudden or gradual onset of ventricular dysfunction. In order to identify mechanisms that may contribute to the deterioration of ventricular function we have generated a transgenic animal model that targets expression of a non- infectious coxsackievirus cDNA to the ventricle. Preliminary data suggests that this unique transgenic model has many characteristics of cardiomyopathy including systolic and diastolic dysfunction, myocardial fibrosis, and induction of the embryonic program of gene expression. We have also shown that coxsackievirus B3 can infect mouse and rat myocytes in culture, and can induce a cytopathic effect that includes myocardial apoptosis. An integrated approach that uses cell culture combined with a transgenic animal model make it possible to address mechanisms by which a defined stimulus can adversely affect myocardial cells in culture and in an intact animal model of cardiomyopathy. In cell culture we propose to evaluate specific mechanisms by which coxsackieviral proteins can induce apoptosis and myofilament disruption. Functional significance of the findings in cell culture will then be evaluated in the transgenic mouse. These experiments are based on the following hypotheses: 1) that specific coxsackieviral proteins, such as protease 2A induce apoptosis and myofilament disruption in cultured cardiomyocytes, and 2) that low level cardiac specific expression of CVB proteins in transgenic mouse myocytes can induce abnormalities in excitation contraction coupling associated with ventricular dysfunction. The following specific aims are, therefore, proposed: 1) Determine whether CVB protease 2A is sufficient to induce viral mediated apoptosis and disruption of myofilaments in cultured neonatal ventricular myocytes, 2) Determine the mechanisms by which CVB3 induces a direct cytopathic effect in adult ventricular myocytes, 3) Examine the hemodynamic, and functional significance of cardiac specific expression of non-infectious CVB cDNA in transgenic mice, and 4) Determine whether cardiac expression of the replication deficient CVB3 genome leads to abnormal ventricular function that is associated with excitation contraction coupling abnormalities and altered contractility in the isolated ventricular myocyte. These experiments will facilitate our understanding of the mechanisms by which ventricular function deteriorates with expression of specific proteins that are associated with cardiomyopathy.