Mechanisms of Long-term Cardiac Ion Channel Regulation

心脏离子通道的长期调节机制

• 批准号: 8069300
• 负责人: Jonathan Satin
• 金额: $ 36.63万
• 依托单位: UNIVERSITY OF KENTUCKY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-06-01 至 2014-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8069300
• 关键词: Abbreviations; Acute; Adrenergic Agents; Adult; Aging; Automobile Driving; C-terminal; Cardiac; Cardiac Myocytes; Cell Nucleus; Chronic; Coupled; Data; Defect; Disease; Down-Regulation; Drug usage; Elements; Event; Functional disorder; Funding; Growth and Development function; Health; Heart; Homeostasis; Ion Channel; L-Type Calcium Channels; Lead; Link; Maintenance; Messenger RNA; Molecular; Monomeric GTP-Binding Proteins; Muscle Cells; Nuclear; Nuclear Translocation; Pathway interactions; Peptides; Pharmaceutical Preparations; Protein Phosphatase 2A Regulatory Subunit PR53; Protein phosphatase; Proteins; Regulation; Reporting; Signal Pathway; Signal Transduction; Structure; Testing; Transducers; Up-Regulation; Ventricular; Work; adrenergic; cardiogenesis; chromatin immunoprecipitation; clinically relevant; heart electrical activity; in vitro Model; in vivo; novel; protein expression; response; sensor; trafficking; transcription factor

DESCRIPTION (provided by applicant): Ca dysregulation in cardiac myocytes contributes to heart development defects and diseases of the aging heart. The long-term objective of this proposal is to provide a molecular mechanism that explains how cardiac L-type Ca channels (LTCC) sense and transduce signals that homeostatically regulate cardiac myocytes. Cardiac myocytes present a conundrum with respect to Ca signaling to the nucleus. Cytosolic Ca amplitude varies >10-fold during each cardiac cycle, yet alterations of Ca somehow are differentially decoded for longer-term transcriptional signaling. In this funding period we will test whether Ca channel activity and the cardiac L-type Ca channel itself encodes Ca signaling for long-term regulation. In the past funding period we discovered that RGK chronically inhibited ICa,L (LTCC current), and this RGK inhibition of ICa,L resulted in a compensatory up-regulation of CaV1.2 mRNA. This suggests that ICa,L block may signal transcriptional events in the nucleus. In new studies we confirmed and extended this notion by showing that LTCC-pharmacological- block, but not internal Ca in general is responsible for perturbing heart development. Along the same lines, in mature heart, long-term blockade of LTCC also causes a compensatory up-regulation of LTCC and ICa,L. Our driving hypothesis is that signaling is not simply determined by Ca, but by active Ca channels. The discovery that mobile segment of LTCC is localized to the nucleus or t-tubules coupled with the recent report that this peptide is a transcription factor drives the exciting new hypothesis that this segment of the LTCC, regulates LTCC expression. We will study this aspect of long-term channel regulation in three aims: 1. We will assess nuclear translocation of a domain of the LTCC, and determine the interaction between LTCC activity and sub- cellular localization; 2. We will determine the ability of LTCC to auto-regulate itself transcriptionally; and 3. We will determine the compensatory changes of SL Ca handling proteins in response to LTCC blockade. This work may provide a missing molecular link between LTCC function and downstream signaling events. PUBLIC HEALTH RELEVANCE: These studies show that widely used clinically-relevant drugs that are used to block LTCC may inadvertently exacerbate heart dysfunction by paradoxically increasing LTCC function. This proposal will lead to understanding of a new mechanism whereby ion channels that control cardiac electrical activity also may control long-term signaling pathways that are critical for maintenance of cardiac structure and function.

描述（由申请人提供）：心肌细胞中的 Ca 失调会导致心脏发育缺陷和衰老心脏疾病。该提案的长期目标是提供一种分子机制，解释心脏 L 型 Ca 通道 (LTCC) 如何感知和转导稳态调节心肌细胞的信号。心肌细胞在向细胞核传递 Ca2+ 信号传导方面存在难题。在每个心动周期中，胞浆 Ca 振幅变化 > 10 倍，但 Ca 的变化在某种程度上被差异化地解码为长期转录信号传导。在本次资助期间，我们将测试 Ca 通道活性和心脏 L 型 Ca 通道本身是否编码 Ca 信号传导以进行长期调节。在过去的资助期间，我们发现 RGK 长期抑制 ICa,L（LTCC 电流），并且 RGK 对 ICa,L 的抑制导致 CaV1.2 mRNA 的补偿性上调。这表明 ICa,L 阻断可能发出细胞核中转录事件的信号。在新的研究中，我们证实并扩展了这一概念，表明 LTCC 药理学阻断（而不是一般的内部 Ca）负责扰乱心脏发育。同样，在成熟心脏中，长期阻断 LTCC 也会引起 LTCC 和 ICa,L 的代偿性上调。我们的驱动假设是信号传导不仅由 Ca 决定，而且由活跃的 Ca 通道决定。 LTCC 的移动片段定位于细胞核或 T 型小管的发现，加上最近报道该肽是转录因子，推动了令人兴奋的新假设，即 LTCC 的该片段调节 LTCC 表达。我们将通过三个目标来研究长期通道调节的这一方面： 1. 我们将评估 LTCC 结构域的核易位，并确定 LTCC 活性与亚细胞定位之间的相互作用； 2.我们将确定LTCC在转录上自动调节自身的能力； 3. 我们将确定 SL Ca 处理蛋白响应 LTCC 阻断的代偿性变化。这项工作可能提供了 LTCC 功能和下游信号事件之间缺失的分子联系。公众健康相关性：这些研究表明，广泛使用的用于阻断 LTCC 的临床相关药物可能会反而增加 LTCC 功能，从而无意中加剧心脏功能障碍。该提议将有助于理解一种新机制，控制心脏电活动的离子通道也可以控制对维持心脏结构和功能至关重要的长期信号传导途径。