Mechanisms regulating SR Ca2+ ATPase in the Atria

心房 SR Ca2 ATP 酶的调节机制

基本信息

批准号：
7609101
负责人：
Muthu Periasamy
金额：
$ 37.5万
依托单位：
OHIO STATE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2008
资助国家：
美国
起止时间：
2008-04-01 至 2010-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7609101
关键词：
Adrenergic Agents Affect Affinity Aging Arrhythmia Atrial Fibrillation Atrial Function Backcrossings C-terminal Ca(2+)-Transporting ATPase Caffeine Calcium Canis familiaris Cardiac Cardiac Myocytes Comparative Study Data Development Diastolic Hypertension Ectopic Expression Excision Frequencies Functional disorder Gene Transfer Genetically Engineered Mouse Gifts Goals Heart Heart Atrium Heart Hypertrophy Heart failure Homeostasis Human Isoproterenol Kinetics Knock-out Knockout Mice Laboratories Left Atrial Function Left Ventricular Function Left ventricular structure Mediating Mediator of activation protein Molecular Weight Mus Muscle Muscle Cells Mutation Myocardium Pathology Performance Phosphoric Monoester Hydrolases Phosphorylation Physiology Play Predisposition Protein Dephosphorylation Protein Kinase Proteins Pump Regulation Research Research Proposals Role Sarcoplasmic Reticulum Set protein Site-Directed Mutagenesis Stress Testing Threonine Phosphorylation Site Transgenic Mice Transgenic Organisms Universities Ventricular Ventricular Function adrenergic base heart function knockout gene mouse model new therapeutic target novel overexpression phospholamban pressure response sarcolipin uptake

项目摘要

DESCRIPTION (provided by applicant): The Sarcoplasmic reticulum (SR) Ca2+ ATPase (SERCA) plays a dominant role in Ca2+ removal and is responsible for maintaining cardiac SR Ca2+ store. The activity of SERCA pump is regulated by two small molecular weight proteins, phospholamban (PLB) and sarcolipin (SLN). It is well documented that PLB is the key mediator of 2-adrenergic response in the ventricle. However, little is known about the role of SLN in cardiac SR calcium homeostasis. Recent studies from our laboratory have shown that SLN is predominantly expressed in the atria. Ectopic expression of SLN in the ventricular myocytes resulted in decreased calcium transients and myocyte contractility. Interestingly, the inhibitory effect of SLN was relieved upon isoproterenol treatment and stimulation at high frequency. Our studies therefore suggest that SLN is a novel regulator of cardiac SERCA pump. In addition, we found that SLN levels are significantly altered in diseased atria (heart failure and arrhythmia) of dogs and human, suggesting that an alteration in SLN /SERCA ratio could contribute to altered Ca2+ transport in failing myocardium. Based on these findings, we hypothesize that SLN is a key mediator of 2-adrenergic response in the atria and changes in its expression level may contribute to altered calcium homeostasis seen in atrial pathophysiology. In order to test these hypotheses, we have generated two transgenic mouse models 1) cardiac-specific over expression of SLN and, 2) SLN knockout (KO). Aim I will test the hypothesis that SLN is the major regulator of SERCA pump and mediates the 2-adrenergic regulation of Ca2+ transport in atria using SLN transgenic, SLN KO and PLB KO mouse models. Aim II will test the hypothesis that SLN action on SERCA pump is direct and its inhibitory function is regulated by phosphorylation and dephosphorylation status. The role of SLN phosphorylation and its interaction with SERCA pump will be assessed using site directed mutagenesis, and adenoviral gene transfer into cardiac myocytes. In addition, we will determine how SLN interaction with SERCA pump affect the kinetics of the SR calcium uptake. Aim III will test the hypothesis that alterations in SLN to SERCA ratio will affect atrial function and predispose the atria to develop atrial pathology including atrial fibrillation upon increased load or stress. We will study the effect of pressure overload induced heart failure and increased pacing of the heart in SLN overexpressing and knockout mice. These studies will provide critical information on the role of SLN in atrial calcium handling and pave the way towards identifying novel therapeutic targets for treating atrial dysfunction including atrial fibrillation. RELEVANCE: We recently identified a novel molecule namely sarcolipin. It is found predominantly in the atrial chamber of the heart and our studies indicate that it may regulate cardiac calcium transport during the beat to beat function of the heart. A major goal of this research proposal is to understand how Sarcolipin regulates Calcium transport and contractility of the atrial muscle. In addition another important goal of this study is to understand its role in atrial pathology. These studies will employ genetically engineered mouse models to understand if loss of Sarcolipin protein has an effect on cardiac function.

描述（由申请人提供）：肌浆网 (SR) Ca2+ ATP 酶 (SERCA) 在 Ca2+ 去除中起主导作用，并负责维持心脏 SR Ca2+ 储存。 SERCA 泵的活性由两种小分子量蛋白质：受磷蛋白 (PLB) 和肌磷脂 (SLN) 调节。有充分证据表明，PLB 是心室 2-肾上腺素能反应的关键介质。然而，人们对 SLN 在心脏 SR 钙稳态中的作用知之甚少。我们实验室最近的研究表明 SLN 主要在心房表达。心室肌细胞中 SLN 的异位表达导致钙瞬变和肌细胞收缩力降低。有趣的是，异丙肾上腺素治疗和高频刺激后，SLN 的抑制作用得到缓解。因此，我们的研究表明 SLN 是心脏 SERCA 泵的新型调节器。此外，我们发现 SLN 水平在狗和人类患病心房（心力衰竭和心律失常）中显着改变，这表明 SLN /SERCA 比率的改变可能导致衰竭心肌中 Ca2+ 转运的改变。基于这些发现，我们假设 SLN 是心房 2-肾上腺素能反应的关键介质，其表达水平的变化可能导致心房病理生理学中钙稳态的改变。为了测试这些假设，我们生成了两种转基因小鼠模型：1）心脏特异性 SLN 过度表达，2）SLN 敲除（KO）。目的我将使用 SLN 转基因、SLN KO 和 PLB KO 小鼠模型检验 SLN 是 SERCA 泵的主要调节剂并介导心房 Ca2+ 转运的 2-肾上腺素能调节的假设。目标 II 将检验以下假设：SLN 对 SERCA 泵的作用是直接的，并且其抑制功能受磷酸化和去磷酸化状态的调节。将使用定点诱变和腺病毒基因转移至心肌细胞来评估 SLN 磷酸化的作用及其与 SERCA 泵的相互作用。此外，我们将确定 SLN 与 SERCA 泵的相互作用如何影响 SR 钙吸收的动力学。目标 III 将检验以下假设：SLN 与 SERCA 比率的改变会影响心房功能，并使心房在负荷或压力增加时容易发生心房病理，包括心房颤动。我们将研究压力超负荷诱导的心力衰竭和 SLN 过度表达和基因敲除小鼠的心脏起搏加快的影响。这些研究将提供关于 SLN 在心房钙处理中的作用的关键信息，并为确定治疗心房功能障碍（包括心房颤动）的新治疗靶点铺平道路。相关性：我们最近发现了一种新分子，即肌磷脂。它主要存在于心脏的心房中，我们的研究表明它可以在心脏逐次跳动功能期间调节心脏钙转运。该研究计划的一个主要目标是了解肌磷脂如何调节钙转运和心房肌的收缩性。此外，本研究的另一个重要目标是了解其在心房病理学中的作用。这些研究将采用基因工程小鼠模型来了解肌磷脂蛋白的缺失是否会对心脏功能产生影响。