IP3 receptor, NOX2 and calcium signaling domains in atrial physiology and pathophysiology

项目摘要/摘要 心房兴奋收缩偶联(ECC)和肌浆网(SR)钙释放有其独特的特点 与心室ECC有明显不同。在ECC过程中，动作电位(AP)启动从 肌浆网钙主要通过兰尼定受体(RyR)钙释放通道储存。房性心动过速 第二，虽然钙释放通道不那么丰富，但三磷酸肌醇受体(IP3R)。IP3R诱导 CA释放(IICR)参与ECC，但也具有非ECC功能，包括对起搏器的贡献 线粒体钙信号的活性和转录因子活性的调节对 病理生理学心房重构。IICR具有性别特异性，并发挥正性肌力作用，但 也有助于心律失常前钙的释放。IICR在心力衰竭(HF)患者的心房组织中表达上调 促进肌浆网钙释放和增强心房收缩，但也会导致交替和 心房颤动。心脏IP3R是翻译后修饰的靶点。新的初步数据 证明在心房肌细胞中，IP3R受IP3和NADPH-氧化酶型ROS共同调节 2(NOX2)，参与ROS依赖的IP3R谷胱甘肽基化。这项提案的总体目标将考验 假设在心房组织中，NOX2/ROS/IP3R信号域负责正性肌力和 IICR的致心律失常作用，并确定HF引起的ROS依赖的IICR调节和 它们对心房重构、交替和心房颤动(AF)风险的影响。三个具体目标是： 具体目标1：确定IP3和ROS共同调节IP3R的机制，并确定其性别特异性 属性。我们将在定义的NOX2/ROS/IP3R中测试IICR受IP3和ROS共同调节的假设 在ECC过程中，IP3R的ROS依赖的谷胱甘肽基化调节心房钙的释放。 除了NOX2之外，用于IP3R调制的细胞ROS来源(线粒体，NOX4)的替代候选， 并将确定IICR的ROS/IP3共同调节的性别特异性属性。 特异性目标2：确定NOX2/ROS/IP3R信号转导通路的心房重构及其对ECC的影响 心衰时释放和转录因子的调节。我们将检验这一假设，即在一个心室的心房组织中 替代NOX2的HF模型ROS源上调IICR，从而改变其对心房肌的贡献 瞬时(CAT)、收缩和转录因子(NFAT)通过核IP3Rs激活。 具体目标3：确定ROS/IICR介导的钙交替倾向增加和 房颤易感性在正常和心力衰竭心房组织中的表达。我们将检验IICR促进起搏诱导的假说 CAT Alternans，在HF中进一步增强，并协同ROS/IICR介导的Alternans产生 一种增加房颤发作敏感性的底物。

PROJECT SUMMARY/ABSTRACT Atrial excitation-contraction coupling (ECC) and sarcoplasmic reticulum (SR) Ca release have unique features and are distinctly different from ventricular ECC. During ECC the action potential (AP) initiates Ca release from the SR Ca stores primarily through the ryanodine receptor (RyR) Ca release channels. The atrial SR has a second, albeit less abundant Ca release channel, the inositol-1,4,5-trisphosphate receptor (IP3R). IP3R induced Ca release (IICR) participates in ECC but also has non-ECC functions, including contribution to pacemaker activity, mitochondrial Ca signaling, and regulation of transcription factor activity important for pathophysiological atrial remodeling. IICR has sex-specific attributes and exerts positive inotropic effects, but also facilitates proarrhythmic Ca release. IICR is upregulated in atrial tissue in heart failure (HF), which facilitates SR Ca release and enhances atrial contraction, but also leads to increased risk of alternans and atrial fibrillation. The cardiac IP3R is target of post-translational modifications. New preliminary data demonstrate that in atrial myocytes the IP3R is co-regulated by IP3 and ROS provided by NADPH-oxidase type 2 (NOX2) and involves ROS-dependent IP3R glutathionylation. The overall goal of this proposal will test the hypothesis that in atrial tissue a NOX2/ROS/IP3R signaling domain is responsible for the positive inotropic and proarrhythmic effects of IICR, and to determine HF induced changes in ROS dependent IICR regulation and their consequences for atrial remodeling, alternans and atrial fibrillation (AF) risk. The 3 specific aims are: Specific aim 1: Define the mechanism of IP3R co-regulation by IP3 and ROS and determine its sex-specific attributes. We will test the hypotheses that IICR is co-regulated by IP3 and ROS in a defined NOX2/ROS/IP3R microdomain and that ROS dependent glutathionylation of IP3R modulates atrial Ca release during ECC. Alternative candidates of cellular ROS sources (mitochondria, NOX4) for IP3R modulation in addition to NOX2, and sex-specific attributes of ROS/IP3 co-regulation of IICR will be determined. Specific aim 2: Determine atrial remodeling of NOX2/ROS/IP3R signaling and its consequences for ECC, Ca release and transcription factor regulation in HF. We will test the hypothesis that in atrial tissue of a ventricular HF model ROS sources alternative to NOX2 upregulate IICR and thereby change its contribution to atrial Ca transient (CaT), contraction, and transcription factor (NFAT) activation through nuclear IP3Rs. Specific aim 3: Determine the mechanisms of ROS/IICR mediated increase in Ca alternans propensity and AF susceptibility in normal and HF atrial tissue. We will test the hypotheses that IICR facilitates pacing induced CaT alternans that is further enhanced in HF, and that synergistically ROS/IICR mediated alternans generates a substrate that increases the susceptibility for AF episodes.