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.

项目摘要 B-肾上腺素受体（BAR）是心脏功能的强大调节剂之一。栏下调（表面受体的丧失）和脱敏（G蛋白偶联受损）是心脏失败的标志。脱敏是通过棒激酶1（Bark1或grk2）响应的条酶1（Bark1或grk2）引发的脱敏化。儿茶酚胺导致心脏反应减少。 B- arrestin结合促进的磷酸化条它们的内吞作用（下调）。磷酸化的条通过介导的去磷酸化函数敏感通过内体中的蛋白质磷酸酶2A（PP2A），并回收回到质膜正如NA¿VE受体准备激活一样。与信念相反，即宣传是一个维护的过程稳态，我们在当前RO1中的机械研究已经确定PI3KG抑制了PP2A活性，从而负面调节棒敏化。我们已经表明，pi3kg磷酸化磷酸化丝氨酸9和93（S9，93）上PP2A（I2PP2A）的抑制剂，该抑制剂与PP2A结合，抑制PP2A活性和阻止棒函数化，有效地确定PI3KG-I2PP2A-PP2A途径调节棒尽管我们已经确定了调节棒敏化的途径，但尚不清楚该途径是否改变并导致心脏肥大和心力衰竭。因此，目标续约是确定在心力衰竭和测试使用一般改变的小鼠的靶向性敏化组成部分是否可以提供有益的压力重塑。我们已经产生了具有野生型心脏过表达的转基因小鼠 I2PP2A（WT I2PP2A TG）或I2PP2A突变体S9，93A（I2PP2A S9，93A TG，模仿Dephospho态）或 S9，93d（I2pp2a S9，93d Tg，磷酸态）。我们的初步研究表明，受WT I2PP2A TG的受到小鼠或I2pp2a S9，93d TG小鼠到心脏应激导致心脏功能障碍加速在I2pp2a S9中明显改善了93A TG小鼠，这表明在bar ensesitization中起关键作用有害的重塑。此外，我们还观察到非古典GBG独立的PI3KG募集到响应促炎性细胞因子TNFA的条可能会抑制PP2A活性导致BAR损失敏化表明TNFA可以通过改变PI3KG-I2PP2A-PP2A轴来调节条形功能。基于这些初步研究，我们假设pi3kg-抑制了bar的脱敏化。心脏应力下的I2PP2A-PP2A途径，并通过靶向释放对棒敏化的抑制作用 I2PP2A可以保留棒功能并防止有害的心脏重塑。我们提出以下内容具体目的是解决该假设：具体目的1：确定是否调节心脏棒发射敏化途径可防止有害心脏重塑对心脏压力，特定目的 2：确定PI3KG介导的I2PP2A-PP2A相互作用及其在BAR中的作用的分子基础敏化，特定目的3：研究介导激动剂独立的分子机制响应TNFA的pi3kg非典型募集和抑制条敏化。确定 PI3KG-I2PP2A-PP2A轴在控制心脏应激的bar敏化中的作用将提供对条功能障碍的全面机械理解，从而鉴定出新的通过靶向钢筋敏化途径来实现心力衰竭的治疗策略。