CARDIAC GROWTH REGULATION

描述 (改编自申请者摘要)心脏对各种不同的 通过改变心肌细胞的大小和功能来刺激血流动力学和体液刺激。 由高血压或瓣膜引起的左心室肥厚 疾病是发病率和死亡率的敏感预测因子，原因是 心肌功能不全。本研究的目的是检验 假设心肌细胞收缩活动本身是一个主要的刺激因素 心肌细胞的生长和功能。该实验方法旨在 确定参与转导的分子机制 向细胞核发出收缩信号。来自先前的体外和体内数据 研究α-肌球蛋白转录调控的研究 重链(α-MHC)基因使它们能够整合核变化 在整体细胞内反应血流动力学负荷的变化。 这项申请涉及四个具体目标：(1)识别 转录因子(S)，与-47bp的顺式作用元件结合 α-MHC基因转录起始点，指定为血流动力学 响应元素(HME)，这是授予的必要条件和充分条件 心肌细胞对该启动子的收缩反应。这 核蛋白(指定为HRP)将从心肌细胞中克隆出来 表达文库通过其与HME序列的结合和 激活α-MHC启动子；(2)研究 收缩刺激通过以下途径调节HRP的转录活性 确定其活性是否受磷酸化调节，确定 它的DNA结合特性及其二聚化反应特性 对收缩刺激；(3)收缩诱导信号的研究 蛋白激酶C-Zeta在磷酸化中的作用途径 和激活HRP；以及(4)通过测定HRP在体内的功能 使用病毒载体系统将基因送入血液动力学 无负荷的异位移植心脏，经历萎缩和 降低α-MHC的表达。这些研究将推动 对负荷调节心脏的分子途径的理解 生长和功能，并有可能导致新的遗传疗法 心脏生长障碍导致病理性肥大。(末尾 摘要)

DESCRIPTION (Adapted from applicants' abstract) The heart responds to various hemodynamic and humoral stimuli by changes in myocyte size and function. Left ventricular hypertrophy such as arises from hypertension or valvular disease is a sensitive predictor for morbidity and mortality due to myocardial dysfunction. The purpose of the present study is test the hypothesis that myocyte contractile activity per se is a major stimulus of cardiomyocyte growth and function. The experimental approach is designed to identify the molecular mechanisms involved in the transduction of the contractile signal to the nucleus. Data from previous in vitro and in vivo studies that examined the transcriptional regulation of the alpha-myosin heavy chain (alpha-MHC) gene allow them to integrate the nuclear changes within the overall cellular response to the changes in hemodynamic load. This application addresses four specific aims: (1) identification of a transcription factor(s) that binds to a cis-acting element at -47 bp of the transcriptional start site of the alpha-MHC gene, designated hemodynamic response element (HME), that is both necessary and sufficient to confer contractile responsiveness to this promoter in cardiac myocytes. This nuclear protein (designated HRP) will be cloned from a cardiomyocyte expression library by its ability to bind to the HME sequence and to activate the alpha-MHC promoter; (2) study the mechanisms by which the contractile stimulus regulates the transcriptional activity of HRP by determining whether its activity is modulated by phosphorylation, determine its DNA binding characteristics, and its dimerization properties in response to the contractile stimulus; (3) study the contractile-induced signaling pathway in which protein kinase C-zeta plays a role in the phosphorylation and activation of HRP; and (4) determine the in vivo function of HRP by using viral vector systems to deliver the gene into the hemodynamically unloaded, heterotopically transplanted heart, that undergoes atrophy and decreased alpha-MHC expression. These studies will advance the understanding of the molecular pathways by which workload regulates cardiac growth and function, and potentially lead to novel genetic therapies of disorders of cardiac growth leading to pathologic hypertrophy. (End of Abstract)