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.

心脏通过以下方式对各种血液动力学和体液刺激作出反应： 肌细胞大小和功能的变化。 左室肥厚 如由高血压或瓣膜疾病引起的， 预测心肌功能不全的发病率和死亡率。 在本申请中，我们提出测试以下假设， 肌细胞收缩活动本身调节着 （α）-肌球蛋白重链（α-MHC）基因。 我们已经确定了一 在转录起始位点-47bp处有顺式作用元件， 指定的血液动力学反应元件（HME），即 必要和足够的，以赋予收缩反应， 自发收缩的心肌细胞。 的HME 含有E盒基序，其结合蛋白（指定为HRP）是 与USF（上游刺激因子）抗原相关。 我们 建议从新生大鼠心肌细胞表达中克隆HRP 通过其特异性结合HME序列的能力，可以将HME与文库结合。 克隆HRP在培养心肌细胞中的表达研究 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是对机械刺激的反应。 的作用 PKC（Z）在信号转导通路中的作用及其潜力 将确定到细胞核的定位。 我们建议研究 甲状腺激素（TH）和收缩功能的联合作用 对（α）-MHC基因转录调节的活性， 了解这种基因在出生时的快速诱导，当TH和 心脏血流动力学正在改变 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MHC调节的（α）-MHC转录。 验证 HRP在体内的转录作用，我们建议过表达HRP， 血流动力学卸载心脏，以直接评估其对 （α）-MHC启动子活性，并确定PKC（Z） HRP的磷酸化是其转录激活所必需的。 这些研究将促进我们对分子的理解 工作负荷调节心脏生长和功能的途径。