Control of KATP channel expression by CaMKII: role in heart failure resistance

CaMKII 对 KATP 通道表达的控制：在心力衰竭抵抗中的作用

• 批准号: 8270783
• 负责人: Denice Hodgson-Zingman
• 金额: $ 37.75万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-04-16 至 2017-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8270783
• 关键词: Acceleration; Action Potentials; Adaptor Signaling Protein; Address; Affect; Binding; Biology; Calcium; Calcium/calmodulin-dependent protein kinase; Cardiac; Cardiac Myocytes; Cardiac Output; Cell Death; Cell membrane; Cells; Cessation of life; Chronic; Consumption; Coupled; Coupling; Data; Development; Down-Regulation; Endocytosis; Energy Metabolism; Figs - dietary; Functional disorder; Generations; Genetic; Goals; Heart; Heart Rate; Heart failure; Homeostasis; Image; Immunofluorescence Immunologic; Incidence; Infarction; Injury; Ion Channel; Ions; Laboratories; Mechanics; Medicine; Membrane; Membrane Proteins; Metabolic; Molecular Biology; Myocardial; Myocardial dysfunction; Organ; Outcome; Patch-Clamp Techniques; Performance; Phosphorylation; Phosphotransferases; Physiological; Potassium; Prevention; Production; Proteins; Public Health; Publishing; Recombinants; Regulation; Relaxation; Resistance; Resources; Role; Signal Pathway; Site; Sodium; Stress; Surface; Testing; Transcription Factor AP-2 Alpha; United States; Ventricular; Work; Workload; adapter protein; base; calmodulin-dependent protein kinase II; combat; cost; energy balance; improved; mortality; mouse model; novel; novel strategies; pressure; protein complex; response

DESCRIPTION (provided by applicant): Heart failure is an enormous public health problem in the United States. Over the past two decades, there has been considerable progress in the treatment of chronic heart failure yet, even with the best of modern therapy, heart failure is stil associated with a 5-year mortality rate of 50%. Therefore, the search for new approaches to treatment and prevention of heart failure is one of the major challenges in medicine. The ATP-sensitive potassium (KATP) channel, one of the most abundant cardiac membrane protein complexes, has the unique ability to adjust membrane excitability in response to changes in the energetic status of the cell. When activated by increased cellular metabolic demand, KATP channel-dependent potassium efflux shortens cardiac action potential duration (APD). This potassium efflux limits sodium and calcium entry into the cell and thus reduces energy requirements for ion homeostasis and contraction, as well as prolongs the diastolic interval that supports myocardial relaxation and replenishment of ATP. Our recent work uncovered that that the ability of the heart to optimize APD and energy utilization depends on the membrane expression level of KATP channels which affects how quickly and efficiently KATP current can adapt to changes in workload. A complete understanding of mechanisms that control membrane KATP channel expression may reveal new avenues to promote cardiac energy efficiency and resistance to heart failure. Based on our preliminary data, we hypothesize that membrane KATP channel expression is coupled with overall cardiac function by calcium/calmodulin dependent protein kinase II (CaMKII). This densely expressed multifunctional kinase targets numerous proteins involved in excitation contraction coupling and excitability to support enhanced cardiac performance, while its persistent activation under pathophysiological conditions promotes cardiomyocyte death and dysfunction. We propose a previously unrecognized downstream signaling pathway of CaMKII activation through phosphorylation of the Kir6.2 pore-forming KATP channel subunit and consequent endocytosis of KATP channels. Under persistent CaMKII activation, the consequent reduction in KATP channel expression would aggravate depletion of cardiac energy resources thus contributing to myocardial injury, cell death and heart failure. We predict that the known beneficial effects on cardiac stress resistance that occur with CaMKII inhibition will depend significantly on membrane retention of KATP channels. In Aim1 we will define the mechanism for CaMKII-dependent endocytosis of KATP channels by use of tagged recombinant KATP channel subunits, confocal immunofluorescence imaging, and molecular biology and patch clamp techniques in cardiomyocytes and HEK293T cells. In Aim 2 we will study heart failure, induced in genetic mouse models with KATP channel expression deficits and cardioselective CaMKII inhibition, to understand the role of CaMKII-dependent KATP channel expression regulation in the generation of the energetic and functional deficits defining heart failure. PUBLIC HEALTH RELEVANCE: Heart failure is an enormous public health problem in the United States where the incidence and mortality are high such that the search for new approaches to treatment and prevention is one of the major challenges in medicine. Membrane expression of KATP channels affects optimization of cardiac energy consumption and resistance to injury. This project will define a novel mechanism for control of KATP channel membrane expression, and will determine the potential for its manipulation in improvement of myocardial energetics and heart failure resistance.

描述（由申请人提供）：心力衰竭是美国的一个巨大的公共卫生问题。在过去的二十年里，慢性心力衰竭的治疗取得了相当大的进展，但即使采用最好的现代治疗方法，心力衰竭仍然与 50% 的 5 年死亡率相关。因此，寻找治疗和预防心力衰竭的新方法是医学上的主要挑战之一。 ATP 敏感钾 (KATP) 通道是最丰富的心脏膜蛋白复合物之一，具有调节膜兴奋性以响应细胞能量状态变化的独特能力。当细胞代谢需求增加而激活时，KATP 通道依赖性钾流出会缩短心脏动作电位持续时间 (APD)。这种钾的流出限制了钠和钙进入细胞，从而减少了离子稳态和收缩的能量需求，并延长了支持心肌松弛和补充 ATP 的舒张期间隔。我们最近的工作发现，心脏优化 APD 和能量利用的能力取决于 KATP 通道的膜表达水平，这会影响 KATP 电流适应工作负荷变化的速度和效率。全面了解控制膜 KATP 通道表达的机制可能会揭示提高心脏能量效率和抵抗心力衰竭的新途径。 根据我们的初步数据，我们假设膜 KATP 通道表达通过钙/钙调蛋白依赖性蛋白激酶 II (CaMKII) 与整体心脏功能耦合。这种密集表达的多功能激酶靶向众多参与兴奋收缩耦合和兴奋性的蛋白质，以支持增强的心脏性能，而其在病理生理条件下的持续激活会促进心肌细胞死亡和功能障碍。我们提出了一条以前未被识别的 CaMKII 激活下游信号通路，通过 Kir6.2 成孔 KATP 通道亚基的磷酸化和随后的 KATP 通道内吞作用。在CaMKII持续激活下，KATP通道表达减少会加剧心脏能量资源的消耗，从而导致心肌损伤、细胞死亡和心力衰竭。我们预测，CaMKII 抑制对心脏应激抵抗的已知有益影响将在很大程度上取决于 KATP 通道的膜保留。 在 Aim1 中，我们将通过使用标记的重组 KATP 通道亚基、共聚焦免疫荧光成像以及心肌细胞和 HEK293T 细胞中的分子生物学和膜片钳技术来定义 KATP 通道的 CaMKII 依赖性内吞作用的机制。在目标 2 中，我们将研究在具有 KATP 通道表达缺陷和心脏选择性 CaMKII 抑制的遗传小鼠模型中诱导的心力衰竭，以了解 CaMKII 依赖性 KATP 通道表达调节在定义心力衰竭的能量和功能缺陷的产生中的作用。 公共卫生相关性：心力衰竭在美国是一个巨大的公共卫生问题，其发病率和死亡率很高，因此寻找新的治疗和预防方法是医学上的主要挑战之一。 KATP 通道的膜表达影响心脏能量消耗和抗损伤的优化。该项目将定义一种控制 KATP 通道膜表达的新机制，并将确定其在改善心肌能量和心力衰竭抵抗方面的潜力。