Molecular basis of Ca2+ leak in heart

心脏Ca2漏的分子基础

• 批准号: 8461982
• 负责人: George S. B. Williams
• 金额: $ 5.83万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-05-16 至 2014-05-15
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8461982
• 关键词: A Mouse; Accounting; Action Potentials; Address; Affect; Arrhythmia; Behavior; Biological; C57BL/6 Mouse; Ca(2+)-Transporting ATPase; Calcium; Cardiac; Cell model; Cell physiology; Cells; Characteristics; Computer Simulation; Coupling; Data; Development; Disease model; Drug Formulations; Endoplasmic Reticulum; Environment; Equilibrium; Event; Foundations; Frequencies; Functional disorder; Future; Goals; Heart; Heart Diseases; Heart failure; Image; Investigation; Ions; L-Type Calcium Channels; Location; Measurement; Membrane; Mentors; Methods; Modeling; Molecular; Movement; Mus; Muscle Cells; Mutant Strains Mice; Mutation; Organelles; Pathway interactions; Physiological; Play; Process; Property; Pump; Qualifying; Research; Rest; Role; RyR2; Ryanodine Receptor Calcium Release Channel; Ryanodine Receptors; Sarcolemma; Sarcoplasmic Reticulum; Series; Signal Transduction; Site; Study models; Techniques; Testing; Ventricular; Ventricular Tachycardia; Work; base; heart cell; heart function; insight; mathematical model; mutant; novel; novel therapeutics; patch clamp; research study; simulation; skills; success; tool; uptake

DESCRIPTION (provided by applicant): The cellular and subcellular movement of calcium (Ca2+) in heart cells underlies cellular contraction and influences electrical behavior. The PI and his co-mentors have recently discovered new features of Ca2+ movement in heart cells that have profound implications for understanding heart function. Here, the PI proposes to investigate the novel discovery of "invisible Ca2+ leak" by combining quantitative mathematical investigations with experimental tests. Ca2+ leak is the loss of Ca2+ from intracellular storage organelles and plays a vital role in maintaining healthy cellular Ca2+ content by balancing uptake from the sarco/endoplasmic reticulum Ca2+ ATPase (SERCA) pump. Understanding Ca2+ leak and its molecular basis is essential for experimental and theoretical examination of cellular physiology, pathophysiology (including heart failure and arrhythmias), and developing new therapeutics. The planned investigation of SR Ca2+ leak will exploit novel and very efficient mathematical tools recently invented by the PI and his co-mentors that will enable a fully stochastic mathematical investigation of the Ca2+ signaling in single cardiac ventricular myocytes. Work by the PI and his co-mentors has provided preliminary mathematical and biological characterization of two components of Ca2+ leak: Ca2+ sparks (see introduction) and "invisible," non-spark Ca2+ leak. These two components appear to play a role in both normal and arrhythmogenic Ca2+ signaling behavior but have yet to be characterized at the molecular level. The proposed work will test this critical Ca2+ signaling behavior by combining mathematical modeling investigations with single mouse ventricular myocyte experiments. Confocal Ca2+ imaging with simultaneous patch clamp experiments will be carried out in enzymatically dissociated cells to inform the modeling and test the findings. Ca2+ sparks, [Ca2+]i transients, and membrane currents will be investigated in myocytes from control mice (C57BL/6) and from mutant mice with specific alterations in the cardiac ryanodine receptor (RyR2) (C57BL/6- R2474S) that produce Ca2+-dependent arrhythmias (see [1]). Preliminary work by the PI and his co-mentors suggest that there are profound differences in the Ca2+ leak characteristics in the control and mutant heart cells. The proposed investigation into SR Ca2+ leak in heart seeks to address two critically important questions on cardiac Ca2+ signaling: 1) What is the molecular mechanism of SR Ca2+ leak in healthy myocytes? and 2) how do arrhythmogenic RyR2 mutations affect SR Ca2+ leak? The unique feature of the proposed work is the combination of modeling and experiments in a richly interactive environment with a strong record of success in such work. For the PI, the investigation nicely supports his long-term plan to combine theoretical investigations with practical and informative tests with the prospect of broadening our understanding of cardiac cellular function.

描述(由申请人提供)：心肌细胞内钙离子的细胞和亚细胞运动是细胞收缩的基础，并影响电行为。PI和他的同事们最近发现了心肌细胞中钙离子运动的新特征，这些特征对理解心脏功能具有深远的意义。在这里，PI建议通过定量的数学研究和实验测试相结合的方式来研究“看不见的钙离子泄漏”这一新发现。Ca~(2+)泄漏是指细胞内存储细胞器中的Ca~(2+)流失，通过平衡肌浆/内质网Ca~(2+)-ATPase(SERCA)泵的摄取，在维持细胞内健康的Ca~(2+)含量方面起着至关重要的作用。了解钙离子泄漏及其分子基础对于细胞生理学、病理生理学(包括心力衰竭和心律失常)的实验和理论检查以及开发新的治疗方法是至关重要的。对肌浆网钙离子泄漏的计划研究将利用PI和他的同事们最近发明的新的非常有效的数学工具，这些工具将使对单个心肌细胞中的钙信号进行完全随机的数学研究成为可能。PI和他的同事们的研究为钙离子泄漏的两种成分提供了初步的数学和生物学特征：钙离子火花(见导言)和“看不见”的非火花钙离子泄漏。这两个组分似乎都在正常和致心律失常的钙信号行为中发挥作用，但尚未在分子水平上表征。这项拟议的工作将通过将数学建模研究与单个小鼠心室肌细胞实验相结合来测试这一关键的钙信号行为。将在酶解离的细胞中进行钙离子共聚焦成像和同步膜片钳实验，以便为建模和测试结果提供依据。将研究来自对照小鼠(C57BL/6)和心脏兰尼定受体(RyR2)特定变化的突变小鼠(C57BL/6-R2474S)的心肌细胞中的钙火花、[钙]i瞬变和膜电流，这些变化会导致钙依赖的心律失常(见[1])。PI和他的同事的初步工作表明，对照和突变心肌细胞的钙泄漏特性存在着深刻的差异。心脏肌质网钙离子泄漏的研究试图解决心脏钙信号中两个至关重要的问题：1)健康心肌细胞肌浆网钙离子泄漏的分子机制是什么？2)致心律失常的RyR2突变是如何影响肌浆网钙离子泄漏的？拟议工作的独特之处是将建模和实验结合在一个交互丰富的环境中，并在这类工作中取得了很好的成功记录。对于PI来说，这项研究很好地支持了他的长期计划，即将理论研究与实际和信息丰富的测试相结合，以拓宽我们对心脏细胞功能的理解。