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

基本信息

批准号：
8992912
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
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-04-16 至 2018-01-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8992912
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 Congestive Heart Failure 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

项目摘要

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.

描述（由申请人提供）：心力衰竭是美国巨大的公共卫生问题。在过去的二十年中，在慢性心力衰竭的治疗方面取得了长足的进步，即使采用了现代疗法的最好，心力衰竭也与5年死亡率50％有关。因此，寻找治疗和预防心力衰竭的新方法是医学的主要挑战之一。 ATP敏感的钾（KATP）通道是最丰富的心脏膜蛋白复合物之一，具有独特的能力，可响应细胞的能量状态变化来调节膜兴奋性。当通过增加的细胞代谢需求激活时，KATP通道依赖性钾外排缩短心脏作用势持续时间（APD）。这种钾外排将钠和钙进入细胞，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电流的速度有效，可以适应工作负载的变化。完全理解控制膜KATP通道表达的机制可能会揭示新的途径，以促进心脏能源效率和对心力衰竭的抵抗力。基于我们的初步数据，我们假设膜KATP通道表达与钙/钙调蛋白依赖性蛋白激酶II（CAMKII）的总体心脏功能相结合。这种密集表达的多功能激酶靶向许多参与激发收缩偶联的蛋白质和兴奋性以支持增强的心脏性能，而在病理生理条件下，其持续的激活促进了心肌细胞死亡和功能障碍。我们提出了通过KiR6.2孔形成KATP通道亚基的磷酸化和随之而来的KATP通道内吞作用，提出了CAMKII激活的先前未识别的下游信号传导途径。在持续的CAMKII激活下，随之而来的KATP通道表达的降低将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抑制作用对心脏应激抗性的已知有益作用将显着取决于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分子生物学和斑块钳技术在心脏模拟细胞和HEK293T细胞中定义KATP通道的CAMKII依赖性内吞作用的机制。在AIM 2中，我们将研究心力衰竭，这是在具有KATP通道表达缺陷和CAMKII抑制的遗传小鼠模型中诱导的，以了解CAMKII依赖性KATP通道表达调节在定义心脏失败的能量和功能缺陷中的作用。