REGULATION OF CARDIOMYOCYTE SURVIVAL

心力衰竭（HF）是儿童期常见的疾病，具有显著的发病率和死亡率。目前的研究 表明心肌细胞凋亡可能在HF的发生发展中起重要作用。我们有 最近证明ROCK 1（Rho相关的，含有卷曲螺旋的蛋白激酶1）是一个关键， 在新生儿心肌细胞中将促凋亡刺激与凋亡联系起来的介体。我们的研究结果表明， 模型中低水平的活化的半胱天冬酶3直接切割并活化ROCK 1; turn放大半胱天冬酶3的激活，导致心脏细胞凋亡的显著放大。重要的是这 ROCK 1活化和半胱天冬酶3活化之间的机械关系发生在衰竭的人类心脏中， 这表明该途径是有效的治疗靶点。项目2中提出的实验将进一步 验证ROCK 1介导的重要性，并建立其机制基础 心肌细胞凋亡特异性目的1将表征ROCK 1激活在心肌细胞中的作用 凋亡最初的实验将确定caspase 3依赖性ROCK 1激活对 用心脏毒性药物治疗后心肌细胞存活和HF进展， 童年HF其他研究将检验ROCK 1激活足以扩增caspase 3的假设 激活并诱导体内心肌细胞凋亡。具体目标2中提出的实验将 建立激活ROCK 1诱导心肌细胞凋亡的分子机制。初始 研究将检验活化的ROCK 1通过线粒体后活化增强caspase 3活化的假设。 调控其他研究将确定是否基于TAT的抗凋亡蛋白的递送可以减弱 激活ROCK 1诱导的心肌细胞凋亡在体外，如果有必要，在体内。统称 项目2中提出的实验将检验ROCK 1介导的caspase 3扩增的假设， 激活在心肌细胞凋亡中起关键作用，并且进一步将确立ROCK 1的作用 对导致儿童HF的获得性心肌损伤的反应信号传导。该项目还将 确定ROCK 1信号传导的操纵是否可以用于治疗性抑制心肌细胞 获得性出生后HF小鼠模型中的细胞凋亡。

Heart Failure (HF) is a common event in childhood with significant morbidity and mortality. Current research indicates that cardiomyocyte apoptosis may contribute significantly to the development of HF. We have recently demonstrated that ROCK1 (Rho-associated, coiled-coil containing protein kinase 1) is a key mediator which links pro-apoptotic stimuli to apoptosis in neonatal cardiomyocytes. Our results suggest a model wherein low levels of activated caspase 3 directly cleave and activate ROCK1; activated ROCK1 in turn amplifies caspase 3 activation, resulting in a marked amplification of cardiac apoptosis. Importantly, this mechanistic relationship between ROCK1 activation and caspase 3 activation occurs in failing human hearts, suggesting that this pathway is a valid therapeutic target. The experiments proposed in Project 2 will further validate the importance of, as well as establish the mechanistic underpinnings of, ROCK1-mediated cardiomyocyte apoptosis. Specific Aim 1 will characterize the role of ROCK1 activation in cardiomyocyte apoptosis. Initial experiments will establish the importance of caspase 3-dependent ROCK1 activation on cardiomyocyte survival and HF progression following treatment with cardiotoxic drugs which induce childhood HF. Other studies will test the hypothesis that ROCK1 activation is sufficient to amplify caspase 3 activation and induce cardiomyocyte apoptosis in vivo. Experiments proposed in Specific Aim 2 will establish the molecular mechanism by which activated ROCK1 induces cardiomyocyte apoptosis. Initial studies will test the hypothesis that activated ROCK1 amplifies caspase 3 activation via post-mitochondrial regulation. Other studies will determine if TAT-based delivery of anti-apoptotic proteins can attenuate activated ROCK1-induced cardiomyocyteapoptosis in vitro, and if warranted, in vivo. Collectively, the experiments proposed in Project 2 will test the hypothesis that ROCK1-mediated amplification of caspase 3 activation plays a critical role in cardiomyocyte apoptosis, and furthermore will establish the role of ROCK1 signaling in response to acquired myocardial injuries which lead to childhood HF. This project will also determine if manipulation of ROCK1 signaling can be exploited to therapeutically inhibit cardiomyocyte apoptosis in a mouse model of acquired postnatal HF.