CA TRANSPORTER EXPRESSION IN HYPERTROPHY & HEART FAILURE

CA 转运蛋白在肥大中的表达

• 批准号: 6027008
• 负责人: Allen Mark Samarel
• 金额: $ 31.33万
• 依托单位: LOYOLA UNIVERSITY CHICAGO
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-01-10 至 2003-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6027008
• 关键词: calcium flux; calcium ion; calcium transporting ATPase; cardiac myocytes; chemical stability; enzyme activity; gene expression; guanine nucleotide binding protein; heart contraction; heart enlargement; heart failure; hormone regulation /control mechanism; ion transport; isozymes; laboratory rat; membrane transport proteins; mitogen activated protein kinase; neurohormones; nucleic acid sequence; protein kinase C; sarcoplasmic reticulum; tissue /cell culture

A 5-year research program is outlined with the broad, long-term objective of elucidating the molecular mechanisms responsible for altered Ca2+ transporter gene expression in patients with cardiac hypertrophy and heart failure. There is now substantial evidence to indicate that expression levels of SERCA2 and NCX1, the major Ca2+ transporters in cardiac muscle, are profoundly altered in the failing human ventricular myocardium. These changes may result in reduced contractile function and increased susceptibility to ventricular arrhythmias. However, the underlying intracellular me4chanisms responsible for these changes, and the signal transduction pathways involved are only now being elucidated. Four specific aims are outlined to clarify these mechanisms in cultured cardiomyocytes, and related them to what may be occurring in hypertrophy and heart failure in experimental animals and man. First, previous work and preliminary data indicate a critical role of PKC activation in SERCA2 down-regulation during hypertrophy and heart failure. We will therefore use molecular biological techniques to over- express and down-regulate specific PKC isozymes to ascertain which PKC isozymes is responsible. Second, we will characterize the [Ca2+]i and Ras-dependent signaling pathways that regulate SERCA2 gene expression. Studies will focus on the non-receptor protein tyrosine kinase PYK2 that is activated by [Ca2+]i and PKC, and that may link G1- coupled receptor activation to the Ras-Raf-MEK-ERK protein kinase cascade. Third, preliminary data indicate that the 3' untranslated region of the SERCA2 mRNA regulates its stability in response to mechanical and neurohormonal stimuli that activate PKCs. Therefore, a series of experiments is outlined to define the cis-acting sequences and trans-acting factors that are involved. Fourth, we will test the hypothesis that activation of PKCs by either neurohormonal or mechanical stimuli (or their combination) up-regulates NXC1 mRNA and protein levels, and begin to analyze the signaling pathways responsible for these changes. The proposed experiments should substantially contribute to our understanding of the mechanisms responsible for altered Ca2+ transporter gene expression in heart failure Future therapeutic strategies targeted towards prevention or reversal of these changes require a thorough understanding of the responsible intracellular mechanisms.

概述了一项为期5年的研究计划，其广泛的长期目标是阐明心脏肥大和心力衰竭患者中Ca 2+转运蛋白基因表达改变的分子机制。现在有大量的证据表明，心肌中主要的Ca 2+转运蛋白SERCA 2和NCX 1的表达水平在衰竭的人心室肌中发生了深刻的改变。这些变化可能导致收缩功能降低和室性心律失常的易感性增加。然而，导致这些变化的潜在细胞内机制以及所涉及的信号转导途径现在才被阐明。四个具体的目标是概述，以澄清这些机制在培养的心肌细胞，并与他们可能发生的肥大和心力衰竭在实验动物和man. First，以前的工作和初步数据表明，在肥大和心力衰竭的SERCA 2下调PKC激活的关键作用。因此，我们将使用分子生物学技术来过度表达和下调特定的PKC同工酶，以确定哪些PKC同工酶起作用。其次，我们将表征调节SERCA 2基因表达的[Ca 2 +]i和Ras依赖性信号通路。研究将集中于非受体蛋白酪氨酸激酶PYK 2，其由[Ca 2 +]i和PKC激活，并且可能将G1偶联受体激活与Ras-Raf-MEK-ERK蛋白激酶级联反应联系起来。第三，初步数据表明，SERCA 2 mRNA的3'非翻译区调节其稳定性，以响应激活PKC的机械和神经激素刺激。因此，一系列的实验概述，以确定所涉及的顺式作用序列和反式作用因子。第四，我们将测试的假设，激活PKC的神经激素或机械刺激（或其组合）上调NXC 1 mRNA和蛋白质水平，并开始分析负责这些变化的信号通路。拟议的实验应大大有助于我们了解的机制，负责改变钙离子转运蛋白基因表达在心力衰竭未来的治疗策略，针对预防或逆转这些变化需要一个负责细胞内机制的透彻理解。