CARDIAC GROWTH REGULATION

心脏生长调节

• 批准号: 2404584
• 负责人: Kaie Margareeta OJAMAA
• 金额: $ 17.99万
• 依托单位: NORTH SHORE UNIVERSITY HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-08-01 至 2000-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2404584
• 关键词: binding proteins; biological signal transduction; developmental genetics; genetic regulation; hormone regulation /control mechanism; isozymes; laboratory rat; major histocompatibility complex; muscle cells; myocardium; myogenesis; myosins; newborn animals; protein kinase C; thyroid hormones; tissue /cell culture; transcription factor; transfection

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. In the present application we propose to test the hypothesis that myocyte contractile activity per se regulates the transcription of the (alpha)-myosin heavy chain (alpha-MHC) gene. We have identified a cis-acting element at -47 bp from the transcription initiation site, designated hemodynamic response element (HME), that is both necessary and sufficient to confer contractile responsiveness in spontaneously contracting cardiomyocytes in culture. The HME contains an E-box motif whose binding protein (designated HRP) is antigenically related to USF (upstream stimulatory factor). We propose to clone HRP from a neonatal rat cardiomyocyte expression library by its ability to bind specifically to the HME sequence. Expression studies of the cloned HRP is cultured cardiac myocytes will confirm its role in contractile-mediated (alpha-)-MHC transcription. In vitro studies will determine its dimerization, DNA binding and transcription activation properties, and whether phosphorylation of HRP occurs in response to the mechanogenic stimulus. The role PKC(Z) in the signal transduction pathway and its potential localization to the nucleus will be determined. We propose to study the combinatorial effects of thyroid hormone (TH) and contractile activity on transcriptional regulation of the (alpha)-MHC gene to understand the rapid induction of this gene at birth when both TH and cardia hemodynamics are changing. The interaction of these activators with general transcription factors (TATA box binding protein and TAFs) will be studied to determine the molecular basis of workload- and hormone-regulated (alpha)-MHC transcription. To verify the transcriptional role of HRP in vivo we propose to overexpress HRP in the hemodynamically unloaded heart to directly assess its effect on (alpha)-MHC promoter activity and to determine whether PKC(Z) phosphorylation of HRP is required for its transcriptional activation. These studies will advance our understanding of the molecular pathways of workload regulated cardiac growth and function.

心脏对各种血流动力学和体液刺激作出反应 肌细胞大小和功能的变化。 左心室肥厚 例如由高血压或瓣膜病引起的，是一种敏感的 心肌功能障碍引起的发病率和死亡率的预测因子。 在本申请中，我们建议检验以下假设： 肌细胞收缩活动本身调节 (α)-肌球蛋白重链 (α-MHC) 基因。 我们已经确定了一个 距转录起始位点 -47 bp 处的顺式作用元件， 指定的血流动力学反应元件（HME），即 赋予收缩反应性所必需和充分的 培养物中自发收缩的心肌细胞。 健康管理学院 包含一个 E-box 基序，其结合蛋白（称为 HRP）是 与USF（上游刺激因子）有抗原相关性。 我们 提议从新生大鼠心肌细胞表达中克隆 HRP 文库通过其与 HME 序列特异性结合的能力来实现。 培养的心肌细胞中克隆的 HRP 的表达研究将 证实其在收缩介导的 (α-)-MHC 转录中的作用。 体外研究将确定其二聚化、DNA 结合和 转录激活特性，以及是否磷酸化 HRP 的发生是对机械刺激的反应。 角色 PKC(Z)在信号转导通路中的作用及其潜力 将确定细胞核的定位。 我们建议学习 甲状腺激素（TH）和收缩力的综合作用 (α)-MHC 基因转录调节活性 了解当 TH 和 贲门血流动力学正在发生变化。 这些激活剂的相互作用 与一般转录因子（TATA 盒结合蛋白和 TAF）将被研究以确定工作量的分子基础 - 和激素调节的 (α)-MHC 转录。 为了验证 HRP 在体内的转录作用我们建议在体内过表达 HRP 血流动力学卸载的心脏直接评估其对 (α)-MHC 启动子活性并确定 PKC(Z) 是否 HRP 的磷酸化是其转录激活所必需的。 这些研究将加深我们对分子的理解 工作负荷调节心脏生长和功能的途径。