Physical and functional coupling between transient outward K+ channel and CaMKII

瞬态外向 K 通道与 CaMKII 之间的物理和功能耦合

• 批准号: 7422330
• 负责人: YANGGAN WANG
• 金额: $ 19.13万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-05-15 至 2010-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7422330
• 关键词: Aftercare; Antibodies; Area; Binding; Calcium; Calmodulin; Cardiac; Cardiac Myocytes; Cardiac Output; Cells; Co-Immunoprecipitations; Complex; Coupled; Coupling; Cyclic AMP-Dependent Protein Kinases; Data; Development; Dilated Cardiomyopathy; Dissociation; Down-Regulation; Electrophysiology (science); Failure; Genes; Genetic; Goals; Heart Hypertrophy; Heart failure; Hypertrophy; Immunoblotting; Ion Channel; Knock-out; Kv4.3 channel; L-Type Calcium Channels; Label; Lead; Life; Localized; Macromolecular Complexes; Membrane; Methods; Mus; Muscle Cells; Pattern; Peptides; Phosphorylation; Phosphorylation Site; Phosphotransferases; Play; Potassium Channel; Process; Proteins; Publishing; Regulation; Reporting; Research; Risk; Role; Signal Transduction; Staging; Techniques; Testing; United States; Ventricular; Work; autocamtide-2; calmodulin-dependent protein kinase II; cell growth; channel blockers; concept; immunocytochemistry; interest; killings; mouse model; patch clamp; programs; research study; response

DESCRIPTION (provided by applicant): Cardiac hypertrophy is initially a compensatory response that augments cardiac output. However, sustained hypertrophy leads to dilated cardiomyopathy and heart failure (HF), which kills more than 262,000 lives a year in United States. Recent studies have demonstrated that the pathological increase of intracellular calcium [Ca2+]i is the primary cause of triggering cardiac hypertrophic gene program. Interestingly, blocking or genetic deletion of transient outward K+ channel (Ito) is capable of triggering cell growth and cardiac hypertrophy. Taken together, Ito may participate functional regulation of [Ca2+]i in cardiac myocytes. We recently reported that blocking of Ito significantly facilitates L-type calcium channel current (ICa) in mouse ventricular myocytes and we hypothesize that there is a functional association between Ito and ICa and that the Ca2+/Calmodulin- dependent kinase II (CaMKII) is involved in the transduction of regulatory signals between Ito and ICa. Here, we extend our work to test these hypotheses. Our first aim is to test whether Ito channel and CaMKII form a macromolecular complex by using techniques of co-immunoprecipitation and immunocytochemistry labeling. The second aim is to test whether CaMKII- Ito channel complex is dynamically functioning in response to Ito blocking (i.e. whether CaMKII will be displaced by Ito channel blocker). The third aim is to test whether ICa facilitation is the result of Ca2+ channel phosphorylation by CaMKII that displaced from CaMKII-Ito channel complex by Ito channel blocker. The electrophysiological (whole-cell patch clamp) and genetic (CaMKII d knockout mouse model) approaches will be employed to test these hypotheses. The proposed concept here is that Ito channel is a reservoir for CaMKII and the displacement of CaMKII by Ito channel blocker increases CaMKII available to facilitate ICa. Although high risk is anticipated due to the early and conceptual stage, the feasibility is strongly suggested by our recently published electrophysiology results and the co-immunoprecipitation data from other group. Testing the proposed hypothesis may lead to a significant and new conceptual framework and a breakthrough in a new area of research. For instance, the role of functional association of ICa and Ito in the development of cardiac hypertrophy and failure will be the immediate area of interest. Cardiac hypertrophy and the consequent heart failure kill more than 262,000 lives a year in United States. This exploratory proposal is focused on a membrane K+ current (transient outward K+ current, Ito) which is consistently found to be decreased in heart failure as a secondary change. Our overall goal is to test whether blocking this membrane ion channel facilitates Ca2+ influx of cardiomyocytes via functional regulation of the cardiac Ca2+ channel (L-type Ca2+ channel) and to explore the underlying mechanisms which may lead to a significant and new conceptual framework of which the down-regulation of Ito may play an important role in promoting the progression of HF process.

描述（由申请人提供）：心脏肥厚最初是增加心输出量的代偿反应。然而，持续的肥厚会导致扩张性心肌病和心力衰竭（HF），在美国每年有超过262,000人因此死亡。最近的研究表明，细胞内钙[Ca2+]i的病理性增加是触发心脏肥厚基因程序的主要原因。有趣的是，瞬时外向K+通道（Ito）的阻断或基因缺失能够触发细胞生长和心脏肥大。综上所述，Ito可能参与心肌细胞[Ca2+]i的功能调节。我们最近报道了Ito阻滞显著促进小鼠心室肌细胞的l型钙通道电流（ICa），我们假设Ito和ICa之间存在功能关联，并且Ca2+/钙调蛋白依赖性激酶II （CaMKII）参与Ito和ICa之间的调节信号转导。在这里，我们扩展了我们的工作来检验这些假设。我们的第一个目的是通过使用免疫共沉淀和免疫细胞化学标记技术来测试Ito通道和CaMKII是否形成大分子复合物。第二个目的是测试CaMKII- Ito通道复合物是否动态地响应Ito通道阻断（即CaMKII是否会被Ito通道阻断剂取代）。第三个目的是测试ICa促进是否是Ca2+通道被CaMKII磷酸化的结果，CaMKII-Ito通道复合物被Ito通道阻滞剂取代。电生理学（全细胞膜片钳）和遗传学（CaMKII基因敲除小鼠模型）方法将被用来检验这些假设。这里提出的概念是，Ito通道是CaMKII的储存库，Ito通道阻滞剂取代CaMKII增加了CaMKII促进ICa的可用性。虽然由于早期和概念阶段，预计风险很高，但我们最近发表的电生理学结果和其他组的共免疫沉淀数据强烈建议可行性。验证所提出的假设可能会导致一个重要的和新的概念框架，并在一个新的研究领域取得突破。例如，ICa和Ito的功能关联在心脏肥厚和衰竭的发展中所起的作用将是当前的研究领域。在美国，每年有超过262,000人死于心脏肥厚和随之而来的心力衰竭。这个探索性的建议集中在膜K+电流（瞬态外向K+电流，Ito），这一直被发现在心力衰竭中作为次要变化而降低。我们的总体目标是测试阻断该膜离子通道是否通过心脏Ca2+通道（l型Ca2+通道）的功能调节促进Ca2+流入心肌细胞，并探索潜在的机制，这可能导致一个重要的和新的概念框架，其中Ito的下调可能在促进HF过程的进展中发挥重要作用。

项目成果

A juvenile murine heart failure model of pressure overload.

压力超负荷的幼年小鼠心力衰竭模型。

• DOI: 10.1007/s00246-010-9833-3
• 发表时间: 2011
• 期刊: Pediatric cardiology
• 影响因子: 1.6
• 作者: Cumbermack,KristopherM;Cheng,Jun;Nong,Yibing;Mahle,WilliamT;Joyner,RonaldW;Border,WilliamL;Wagner,MaryB;Fyfe,DerekA;Leong,Traci;Wang,Yanggan
• 通讯作者: Wang,Yanggan

Stretch current-induced abnormal impulses in CaMKIIδ knockout mouse ventricular myocytes.

• DOI: 10.1111/jce.12060
• 发表时间: 2013-04
• 期刊: Journal of cardiovascular electrophysiology
• 影响因子: 2.7
• 作者: Lai D;Xu L;Cheng J;Guilbert AB;Lim HJ;Fu G;Wang Y
• 通讯作者: Wang Y