Novel Regulation of Beta Andregenic Receptor Function

β雄激素受体功能的新调控

基本信息

批准号：
8630940
负责人：
Sathyamangla V Prasad
金额：
$ 39.63万
依托单位：
CLEVELAND CLINIC LERNER COM-CWRU
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 2017-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8630940
关键词：
ADRBK1 gene Address Adenovirus Vector Adrenergic Receptor Adult Agonist Arrestins Back Belief Binding Cardiac Catecholamines Cell membrane Chronic Coupling Dissociation Down-Regulation Embryo Endocytosis Endosomes Event Fibroblasts Functional disorder Funding GTP-Binding Proteins Goals Heart Heart Hypertrophy Heart failure Homeostasis In Vitro Inflammatory Infusion procedures Isoproterenol Knockout Mice Lead Mainstreaming Maps Mediating Molecular Mus Muscle Cells Pathway interactions Peptides Pharmaceutical Preparations Phosphatidylinositols Phosphorylation Phosphotransferases Plasma Play Process Protein Dephosphorylation Protein phosphatase Proteins Recycling Regulation Research Role SET gene Serine Signal Transduction Stress Surface TNF gene Testing Transgenic Mice Tumor Necrosis Factor Receptor base constriction cytokine desensitization in vivo inhibitor/antagonist mouse model mutant new therapeutic target novel novel therapeutics overexpression prevent public health relevance receptor receptor function research study response

项目摘要

PROJECT SUMMARY b-adrenergic receptors (bARs) are one of the powerful regulators of cardiac function. bAR downregulation (loss of surface receptors) and desensitization (impaired G-protein coupling) are hallmarks of a failing heart. Desensitization is initiated by phosphorylation of bARs by bAR kinase 1 (bARK1 or GRK2) in response to catecholamines resulting in reduced cardiac responses. b-arrestin binds phosphorylated bARs facilitating their endocytosis (downregulation). Phosphorylated bARs are resensitized by dephosphorylation mediated through protein phosphatase 2A (PP2A) in the endosomes and are recycled back to the plasma membrane as na¿ve receptor ready for activation. Contrary to the belief that resensitization is a process that maintains homeostasis, our mechanistic studies in the current RO1 have identified that PI3Kg inhibits PP2A activity, thereby negatively regulating bAR resensitization. We have shown that PI3Kg phosphorylates endogenous inhibitor of PP2A (I2PP2A) on serine 9 & 93 (S9, 93) that robustly binds to PP2A, inhibiting PP2A activity and blocking bAR resensitization, effectively determining that the PI3Kg-I2PP2A-PP2A pathway regulates bAR resensitization. Although we have identified the pathway that regulates bAR resensitization, it is not known whether this pathway is altered and contributes to cardiac hypertrophy and heart failure. Therefore, the goal of the renewal is to determine whether the resensitization pathway is altered in conditions of heart failure and test whether targeting components of resensitization using genetically altered mice could provide beneficial remodeling upon stress. We have generated transgenic mice with cardiac overexpression of wild type I2PP2A (Wt I2PP2A Tg) or I2PP2A mutants S9, 93A (I2PP2A S9, 93A Tg, mimicking dephospho state) or S9, 93D (I2PP2A S9, 93D Tg, phospho state). Our preliminary studies show that subjecting Wt I2PP2A Tg mice or I2PP2A S9, 93D Tg mice to cardiac stress results in accelerated cardiac dysfunction which is markedly ameliorated in I2PP2A S9, 93A Tg mice suggesting a critical role for bAR resensitization in deleterious remodeling. Additionally, we also observed non-classical Gbg-independent PI3Kg recruitment to bARs in response to pro-inflammatory cytokine TNFa which may inhibit PP2A activity leading to loss in bAR resensitization suggesting that TNFa could regulate bAR function by altering the PI3Kg-I2PP2A-PP2A axis. Based on these preliminary studies, we hypothesize that bAR resensitization is inhibited by the PI3Kg- I2PP2A-PP2A pathway upon cardiac stress and releasing the inhibition on bAR resensitization by targeting I2PP2A could preserve bAR function and prevent deleterious cardiac remodeling. We propose the following specific aims to address the hypothesis: Specific aim 1: To determine whether regulating cardiac bAR resensitization pathway prevents deleterious cardiac remodeling in response to cardiac stress, Specific aim 2: To identify the molecular basis of PI3Kg mediated I2PP2A-PP2A interaction and its role in bAR resensitization, Specific aim 3: To investigate the molecular mechanisms mediating agonist independent non-canonical recruitment of PI3Kg and inhibition of bAR resensitization in response to TNFa. Determining the role of PI3Kg-I2PP2A-PP2A axis in regulating bAR resensitization in response to cardiac stress will provide comprehensive mechanistic understanding of bAR dysfunction leading to identification of novel therapeutic strategies for heart failure by targeting bAR resensitization pathway.

项目概要 b-肾上腺素受体 (bAR) 是心脏功能下调的强大调节剂之一。（表面受体丧失）和脱敏（G 蛋白偶联受损）是心脏衰竭的标志。脱敏是通过 bAR 激酶 1（bARK1 或 GRK2）磷酸化 bAR 来启动的，以响应儿茶酚胺导致心脏反应降低，β-抑制蛋白与磷酸化的 bAR 结合，促进心脏反应。它们的内吞作用（下调）通过去磷酸化介导而重新敏感。通过内体中的蛋白磷酸酶 2A (PP2A) 并循环回到质膜作为 na¿与重新敏化是一个维持过程的观点相反。体内平衡，我们在当前 RO1 中的机制研究发现 PI3Kg 抑制 PP2A 活性，我们已经证明 PI3Kg 从而磷酸化内源性。丝氨酸 9 和 93（S9、93）上的 PP2A (I2PP2A) 抑制剂，可与 PP2A 牢固结合，抑制 PP2A 活性并阻断bAR再敏化，有效确定PI3Kg-I2PP2A-PP2A通路调节bAR 尽管我们已经确定了调节 bAR 重新敏化的途径，但尚不清楚。该途径是否发生改变并导致心脏肥大和心力衰竭。更新的目的是确定重敏途径是否处于心力衰竭的情况下，并且测试使用基因小鼠进行再敏化的靶向成分是否可以提供有益的效果我们已经产生了野生型心脏过度表达的转基因小鼠。 I2PP2A (Wt I2PP2A Tg) 或 I2PP2A 突变体 S9、93A (I2PP2A S9、93A Tg，模拟去磷酸状态) 或 S9，93D（I2PP2A S9，93D Tg，磷酸化状态）。我们的初步研究表明，Wt I2PP2A Tg。小鼠或 I2PP2A S9、93D Tg 加速小鼠心脏应激导致心脏功能障碍，这是在 I2PP2A S9、93A Tg 小鼠中显着改善，表明 bAR 再敏化在此外，我们还观察到非经典的独立于Gbg的PI3Kg招募。 bAR 响应促炎细胞因子 TNFa，可能抑制 PP2A 活性，导致 bAR 损失再敏化表明 TNFa 可以通过改变 PI3Kg-I2PP2A-PP2A 轴来调节 bAR 功能。基于这些初步研究，我们大胆认为 bAR 再敏化受到 PI3Kg- 的抑制 I2PP2A-PP2A通路对心脏应激的影响并通过靶向释放对bAR再敏化的抑制 I2PP2A 可以保留 bAR 功能并防止有害的心脏重塑。解决假设的具体目标：具体目标 1：确定是否调节心脏 bAR 再敏化途径可防止响应心脏应激而发生有害的心脏重塑，具体目标 2：确定 PI3Kg 介导的 I2PP2A-PP2A 相互作用的分子基础及其在 bAR 中的作用再敏化，具体目标 3：研究介导激动剂独立的分子机制 PI3Kg 的非典型募集和对 TNFa 响应的 bAR 重新敏化抑制。 PI3Kg-I2PP2A-PP2A轴在调节bAR再敏化以响应心脏应激中的作用将提供对 bAR 功能障碍的全面机制理解，从而识别新的通过靶向bAR再敏化途径治疗心力衰竭。