B-arrestin Biased B1- and B2-Adrenergic Receptor Signaling

摘要 B-arrestins是一种多功能蛋白，在激动剂刺激后被招募到G蛋白偶联受体(GCPRs)。虽然(3-arrestin)的经典作用是介导受体脱敏，但这种PPG的研究人员最近的工作表明，P-arrestin可以在缺乏 经典的G蛋白激活。B-arrestin介导的不依赖于G蛋白的信号的存在要求受体采用多种“活性”构象或“配体选择状态”。独一无二的能力 配体-受体构象促进B-arrestin信号转导是一个新兴的概念，被称为“偏向信号转导”。P-An-Estin偏向的p-肾上腺素能信号转导的分子机制 PAR的受体及其在心脏中的生理作用尚不清楚。在这个方案中，我们将检验这样一种假设，即突变的Pi-和P2可以被设计成选择性地刺激不依赖G蛋白激活的p-arrestin偏向信号，以及p-arrestin偏向的信号将促进心肌细胞的存活，以限制对病理刺激的心力衰竭的发展。因此，这项研究的具体目标是： 目的1：设计对p-arrestin募集有选择性偏向的Bp1 AR突变体。 目标2：确定激活机制 以及在没有G蛋白激活的情况下，由P1AR和B2AR突变体激活的信号通路。 目的：检测β-arrestin结合的BP2AR突变体TYY和B1AR突变体是否在激动剂刺激和缺血后激活心肌保护信号。 目的：在体内检测B-arrestin偏向的bp2AR突变体Tyy和pAR突变体pAR在病理性应激条件下是否具有心脏保护作用。 通过探索这些目标，我们将确定G蛋白不依赖于BAR的激活可能导致刺激心肌保护信号的途径。如果我们的假设是正确的，我们将证明配体受到刺激 选择性激活B-arrestin信号通路的PAR具有心脏保护作用。由于，根据定义，给药不刺激G蛋白信号的配体是B-Blackade，我们将为开发一类全新的受体阻滞剂提供概念证明。我们相信，这些数据将为开发新型p-arrestin偏向治疗剂来治疗人类心力衰竭提供相当大的推动力。

Abstract B-arrestins are multifunctional proteins that are recruited to G protein-coupled receptors (GCPRs) following agonist stimulation. While the classical role of (3-arrestin is to mediate receptor desensitization, work by investigators of this PPG have recently shown that P-arrestin can stimulate signaling in the absence of classical G protein activation. The existence of B-arrestin-mediated signaling independent of G proteins requires that receptors adopt multiple "active" conformations or "ligand selective states". The ability of unique ligand-receptor conformations to promote preferential B-arrestin signaling is an emerging concept known as "biased signaling". The molecular mechanisms that underlie p-an-estin-biased signaling for the p-adrenergic receptor of (PAR), and its physiological consequences in the heart, are not known. In this proposal, we will test the hypothesis that mutant p i - and P2 can be engineered that will selectively stimulate p-arrestinbiased signaling independent of G protein activation, and that p-arrestin-biased signaling will promote cardiomyocyte cell survival to limit the development of heart failure in response to pathological stimuli. Accordingly, the specific aims of the study are: Aim 1: To engineerBp1 AR mutants that show selective bias for p-arrestin recruitment. Aim 2: To identify the mechanism of activation and signaling pathways activated by P1AR and B2AR mutants in the absence of G protein activation. Aim 3: To test in adult cardiomyocytes whether p-arrestin-biasedBP2AR TYY and B1 AR mutants activate cardioprotective signaling in response to agonist stimulation and ischemia. Aim 4: To test in vivo whether the B-arrestin-biased Bp2AR TYY and pi AR mutant activities cardioprotective pathways under conditions of pathological stress. By exploring these aims, we will define the pathways by which G protein-Independent activation of BARs may lead to stimulation of cardioprotective signaling. If our hypothesis is correct, we will show that ligandstimulated PARS, which selectively activate B-arrestin signaling pathways, are cardioprotecitve. Since, by definition, the administration of a ligand that does not stimulate G protein signaling is B-blackade, we will have demonstrated proof-of concept for the development of an entirely novel class of receptor blockers. We believe these data will provide considerable impetus for the development of novel p-arrestin-biased therapeutic agents to treat human heart failure.