Targeting of B-AR/GBy signaling in the heart with small molecules

描述（由申请人提供）：心力衰竭（HF）是一种预后不良的衰弱性疾病。通过心脏G蛋白G？？亚基是HF病理生理学的重要组成部分。它们将升高水平的细胞溶质G蛋白偶联受体激酶2（GRK 2，bARK 1）募集至HF中激动剂刺激的b-AR，导致慢性b-AR脱敏和下调，这是HF的标志。以前的数据表明，抑制G？？信号传导及其与GRK 2的相互作用可能在HF中具有治疗价值。我们最近开发了一种新的小分子靶向策略，选择性地抑制G？？结合相互作用，并确定了几个G？？小分子抑制剂（Bonacci等，Science，2006）。特别是，化合物M119和gallein，基本上相同的结构和功能，被发现阻止G？？- 体外GRK 2相互作用。我们的初步数据进一步表明，它们减少GRK 2膜募集，增强腺苷酸环化酶活性，并增加对b-AR激动剂反应的分离的成年心肌细胞的收缩性。在体内，全身递送使急性药理学HF模型中的心脏功能、形态和GRK 2表达正常化。重要的是，当给予已建立HF的小鼠时，持续一个月的每日治疗停止了HF和病理性心脏重塑的进展。最近的数据表明，肾上腺G？？HF中的GRK 2信号传导导致肾上腺α 2-AR反馈抑制肾上腺儿茶酚胺释放的脱敏。这些数据表明，同时抑制心脏和肾上腺G？？- GRK 2信号传导可以在HF中具有实质性的治疗益处。病理性心脏G？最近发现信号传导与T188处的新的、持续的ERK 1/2磷酸化相互作用，并导致这种持续的磷酸化事件与HF直接相关。最后，G？也向PI 3 K？发出信号，唯一的G？- 调节PI 3 K。PI3K？还是PI 3 K？与GRK 2的相互作用及其对G？？还已知在HF模型中使2-AR信号传导和心脏功能正常化。我们现在已经确定了特定的G？？抑制性化合物阻断G？与GRK 2、PI 3 K？或两者我们的总体假设是，选择性小分子靶向G？？在心脏和肾上腺中的应用是HF的一种新的治疗范例，一般和选择性G？？化合物将提高我们目前的理解病理G？？在心脏发出信号。为了解决这一假设，我们提出了以下具体目标：1）确定小分子G？HF手术模型中的抑制。2)确定肾上腺小分子G？？HF中的抑制。3)确定G的作用？与新的ERK 1/2通路，GRK 2或PI 3 K？病理性心脏信号传导、肥大和心肌细胞收缩性。总之，我们有令人兴奋的初步数据，确定选择性，生物可利用的G？？抑制性化合物，其既预防HF又阻止HF进展。本提案中概述的实验可能为HF提供一种新的治疗策略。 公共卫生相关性：心力衰竭（HF）是一种预后不良的衰弱性疾病。该提案旨在研究新鉴定的生物可利用化合物，靶向已建立的HF途径。成功完成本提案中概述的实验将增强我们目前对已建立的HF信号通路的理解，并可能为HF提供新的治疗策略。

DESCRIPTION (provided by applicant): Heart failure (HF) is a debilitating disease with poor prognosis. Excess signaling through cardiac G-protein G?? subunits is an important component of HF pathophysiology. They recruit elevated levels of cytosolic G-protein coupled receptor kinase 2 (GRK2, bARK1) to agonist-stimulated b-ARs in HF, leading to the chronic b-AR desensitization and down-regulation that are hallmarks of HF. Previous data has suggested that inhibiting G?? signaling and its interaction with GRK2 could be of therapeutic value in HF. We recently developed a novel small molecule targeting strategy to selectively inhibit G?? binding interactions, and identified several G?? small molecule inhibitors (Bonacci et al, Science, 2006). In particular, compounds M119 and gallein, essentially identical in both structure and function, were found to block G?? -GRK2 interaction in vitro. Our preliminary data further demonstrate that they reduce GRK2 membrane recruitment, enhanced adenylyl cyclase activity, and increased contractility in isolated adult cardiomyocytes in response to b-AR agonist. In vivo, systemic delivery normalized cardiac function, morphology and GRK2 expression in an acute pharmacologic HF model. Importantly, daily treatment for one month halted the progression of HF and pathologic cardiac remodeling when administered to mice with established HF. Recent data demonstrates that elevated adrenal G?? -GRK2 signaling in HF leads to desensitization of adrenal a2-AR feedback inhibition of adrenal catecholamine release. These data suggest that simultaneous inhibition of both cardiac and adrenal G?? -GRK2 signaling could be of substantial therapeutic benefit in HF. Pathologic cardiac G?? signaling was recently found to interact with and result in novel, sustained ERK1/2 phosphorylation at T188; this sustained phosphorylation event has been directly associated with HF. Finally, G?? also signals to PI3K?, the only G?? - regulated PI3K. Large peptide disruption of either PI3K? activity or of PI3K? interaction with GRK2 and their recruitment to G?? is also known to normalize 2-AR signaling and cardiac function in HF models. We have now identified specific G?? inhibitory compounds that block G?? interaction with GRK2, PI3K?, or both. Our overall hypothesis is that selective small molecule targeting of G?? in the heart and in the adrenal gland is a novel therapeutic paradigm for HF, and that general and selective G?? compounds will enhance our current understanding of pathologic G?? signaling in the heart. To address this hypothesis, we propose the following specific aims: 1) Determine the efficacy and cardiac specificity of small molecule G?? inhibition in surgical models of HF. 2) Determine the adrenal role of small molecule G?? inhibition in HF. 3) Determine the role of G?? interaction with a novel ERK1/2 pathway, GRK2 or PI3K? in pathologic cardiac signaling, hypertrophy and cardiomyocyte contractility. In summary, we have exciting preliminary data identifying selective, bioavailable G?? inhibitory compounds that both prevent HF and halt HF progression. Experiments outlined in this proposal may provide a novel therapeutic strategy for HF. PUBLIC HEALTH RELEVANCE: Heart failure (HF) is a debilitating disease with poor prognosis. This proposal aims to investigate newly identified bioavailable compounds targeting an established HF pathway. Successful completion of experiments outlined in this proposal will enhance our current understanding of an established HF signaling pathway, and may provide a novel therapeutic strategy for HF.