Regulation of Cardiac Kv Channel Expression

心脏 Kv 通道表达的调节

• 批准号: 8258221
• 负责人: EDWIN S LEVITAN
• 金额: $ 38.75万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-12-20 至 2014-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8258221
• 关键词: 3' Untranslated Regions; AUF1A protein; Address; Affect; Angiotensin II; Animals; Apoptosis; Arrhythmia; Binding; Cardiac; Cardiac Myocytes; Cause of Death; Congestive Heart Failure; Endocytosis; Endosomes; Funding; Gene Expression; Generations; Genes; Genetic Transcription; Heart; Heart failure; Histology; Hormones; Human; Hypertension; Incidence; Infusion procedures; Knockout Mice; Lead; MAPK14 gene; Mammals; Measurement; Mechanics; Mediating; Messenger RNA; Molecular; NADPH Oxidase; Oxidases; Pathologic; Pathway interactions; Phase; Phosphotransferases; Potassium Channel; Proteins; Pump; RNA Degradation; RNA Stability; Regulation; Reporter; Role; Signal Pathway; Signal Transduction; Stretching; Sudden Death; Superoxides; Testing; Time; Transcriptional Regulation; Up-Regulation; base; calmodulin-dependent protein kinase II; constriction; follow-up; heart function; in vivo; insight; male; mitogen-activated protein kinase p38; novel; pressure; promoter; public health relevance; research study; response; superoxide-generating NADPH oxidase; therapeutic target

DESCRIPTION (provided by applicant): Heart failure is associated with remodeling of the electrical and mechanical function of the heart. A common feature of electrical remodeling seen under a wide variety of pathologic states in many mammals is decreased expression of transient outward current (Ito) channels, which alters heart function and may contribute to arrhythmias that cause sudden death. Experiments in the current funding period showed that Kv4.3 messenger RNA (mRNA), which limits Ito channel expression in humans, is destabilized in cultured cardiac myocytes by stretch and Angiotensin II (AII), a hormone implicated in hypertension and congestive heart failure. Destabilization is induced by Nadph oxidase (Nox)-generated superoxide and activation of ASK1 and p38 kinase, resulting in induced expression of AUF1, a protein upregulated in human heart failure that can directly bind to a non-canonical sequence in the channel mRNA. Our recent studies show that AII acts via endosomes and CamKII (calmodulin dependent protein kinase II) to induce biphasic activation of p38 kinase. Furthermore, the AUF1 promoter is activated, implicating transcriptional regulation. Finally, preliminary experiments suggest that AUF1 knockout mice are compromised in their response to transverse aortic constriction (TAC), showing that AUF1 is important for the in vivo cardiac response to pressure overload. Here we study the signaling responsible for downregulating Kv4.3 gene expression, because (a) this channel is an evolutionarily conserved target of cardiac electrical remodeling, (b) AUF1 may regulate expression of many genes in the pathologic heart, (c) Nox, CamKII and p38 kinase have been implicated in heart failure and cardiac myocyte apoptosis, and (d) delayed endosome-induced p38 kinase signaling may be a therapeutic target for maintaining cardiac function without arrhythmia during heart failure. Aim 1 will determine the temporal organization of endosome-superoxide signaling in cardiac myocytes. Aim 2 will determine the mechanisms responsible for enhanced expression and function of AUF1. Aim 3 will use knockout mice to elucidate in vivo how AUF1 affects the healthy and pathologic heart. New molecular and cellular mechanisms for controlling cardiac myocyte gene expression will be revealed by these studies. PUBLIC HEALTH RELEVANCE: Heart failure, a leading cause of death, is associated with signaling that leads to poor cardiac pumping and arrhythmias that can induce sudden death. Based on studies of cardiac K+ channel expression, we have found that endosomes and superoxide induce a delayed phase of signaling which results in expression of an mRNA destabilizing protein. Elucidating this pathway and its downstream effects on channels and other cardiac targets may lead to new therapies for treating heart failure.

描述（由申请人提供）：心力衰竭与心脏电功能和机械功能的重塑相关。在许多哺乳动物的各种病理状态下观察到的电重塑的一个共同特征是瞬态外向电流（Ito）通道的表达减少，这会改变心脏功能并可能导致导致猝死的心律失常。当前资助期间的实验表明，限制人类 Ito 通道表达的 Kv4.3 信使 RNA (mRNA) 在培养的心肌细胞中会因拉伸和血管紧张素 II (AII)（一种与高血压和充血性心力衰竭有关的激素）而不稳定。 Nadph 氧化酶 (Nox) 产生的超氧化物以及 ASK1 和 p38 激酶的激活会引起不稳定，从而诱导 AUF1 表达，AUF1 是一种在人类心力衰竭中上调的蛋白质，可以直接与通道 mRNA 中的非规范序列结合。我们最近的研究表明，AII 通过内体和 CamKII（钙调蛋白依赖性蛋白激酶 II）发挥作用，诱导 p38 激酶的双相激活。此外，AUF1 启动子被激活，涉及转录调控。最后，初步实验表明AUF1敲除小鼠对横主动脉缩窄（TAC）的反应受到损害，这表明AUF1对于体内心脏对压力超负荷的反应很重要。在这里，我们研究负责下调 Kv4.3 基因表达的信号传导，因为 (a) 该通道是心脏电重塑的进化保守靶标，(b) AUF1 可能调节病理心脏中许多基因的表达，(c) Nox， CamKII 和 p38 激酶与心力衰竭和心肌细胞凋亡有关，并且 (d) 延迟的内体诱导的 p38 激酶信号传导可能是维持心脏功能而不出现心律失常的治疗靶点 失败。目标 1 将确定心肌细胞中内体超氧化物信号传导的时间组织。目标 2 将确定增强 AUF1 表达和功能的机制。目标 3 将使用基因敲除小鼠在体内阐明 AUF1 如何影响健康和病理心脏。这些研究将揭示控制心肌细胞基因表达的新分子和细胞机制。 公共卫生相关性：心力衰竭是死亡的主要原因，它与导致心脏泵血不良和心律失常的信号传导有关，从而导致猝死。基于心脏 K+ 通道表达的研究，我们发现内体和超氧化物诱导信号传导的延迟期，从而导致 mRNA 不稳定蛋白的表达。阐明这一途径及其对通道和其他心脏靶标的下游影响可能会带来治疗心力衰竭的新疗法。