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）：心力衰竭与心脏的电气和机械功能的重塑有关。在许多哺乳动物中，在多种病理状态下看到的电重塑的一个共同特征是瞬时向外电流（ITO）通道的表达降低，这会改变心脏功能，并可能导致心律不齐，从而导致猝死。当前资金期间的实验表明，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不稳定，这是通过拉伸和血管紧张素II（AII）（一种激素），这是一种与高血压和充血性心力衰竭有关的激素。 NADPH氧化酶（NOX）生成的超氧化物和ASK1和p38激酶的激活诱导了不稳定，从而导致AUF1的表达，AUF1的表达是人类心力衰竭中上调的蛋白质，可以直接结合通道mRNA中的非传统序列。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）起作用，诱导p38激酶的双相激活。此外，AUF1启动子被激活，暗示转录调控。最后，初步实验表明，AUF1基因敲除小鼠在对横向主动脉收缩（TAC）的反应中受到损害，这表明AUF1对体内心脏对压力过载的反应很重要。在这里，我们研究了负责下调KV4.3基因表达的信号，因为（a）此渠道是心脏电气重塑的进化保守的靶标，（b）AUF1可能调节许多基因在病理心脏中的表达，（c）NOX，CAMKII和P38激酶已与心脏失败和p38激酶有关。激酶信号传导可能是在心力衰竭期间保持心脏功能无心律失常的治疗靶点。 AIM 1将确定心肌细胞中内染色体塞氧化物信号传导的时间组织。 AIM 2将确定负责增强AUF1表达和功能的机制。 AIM 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。这些研究将揭示用于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：心力衰竭是导致死亡的主要原因，与信号导致心脏泵送和心律不齐的信号相关，可导致猝死。基于对心脏K+通道表达的研究，我们发现内体和超氧化物会诱导信号传导延迟的相位，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导致治疗心力衰竭的新疗法。