GPCR Signaling Through a Novel NF-kB Pathway

描述（由申请人提供）：血管炎症是动脉粥样硬化发展的关键因素。与脂质沉积的作用相结合，炎症促进内皮功能障碍、平滑肌增殖和基质不稳定，这些不良事件加剧了发展中的动脉粥样硬化病变，并可能最终导致其破裂和血管血栓形成。炎症的来源多种多样，但其中最重要的是刺激内皮细胞表面上存在的G蛋白偶联受体（GPCR）的循环物质。这些包括各种各样的肽配体、胺、糖蛋白和酶。活化的受体然后通过刺激多个途径传递细胞内信号，包括ERK、Akt、JNK、p38 MAPK和STAT的那些，但是NF-κ B转录因子的活化被认为是最重要和有效的促炎信号之一。我们已经发现了一个信号转导途径，介导NF-κ B激活响应GPCR激动剂，血管紧张素II和凝血酶。该途径集中于由分子CARMA 3、Bcl 10和MALT 1组成的多蛋白信号传导模块的组装，我们现在将其称为“CBM信号体”。在该信号体中，MALT 1蛋白作为主要效应子，协调经典NF-κ B机制的下游刺激。似乎这种CBM信号体对于由识别溶血磷脂酸（LPA）、IL-8、内皮素-1和SDF-1/CXCL 12的GPCR诱导的NF-κ B活化也是关键的。这些物质中的大多数已经明确与血管功能障碍、炎症和动脉粥样硬化形成相关，并且认为它们激活NF-κ B的能力是这些病理生理反应的核心。因此，我们认为CBM信号体是负责在血管壁中传递促炎信号的机械枢纽，因为它受到多种GPCR激动剂的刺激。因此，靶向信号体的作用可能被证明是管理动脉粥样硬化形成的高效策略。在这个建议中，我们将探讨CBM信号体和血管病理学的具体方面之间的机制联系。这将通过三个具体目标来实现：（1）研究阻断CBM活性对NF-κ B活化的影响， 本研究的目的是：（1）探索CBM信号体在GPCR活化后组装的机制;（2）研究CBM信号体在GPCR活化后组装的机制;（3）测试阻断CBM活性对体内致动脉粥样硬化过程的影响。我们预计，这些结果将广泛地为减少炎症对动脉粥样硬化形成的贡献的药物策略的发展提供信息。

DESCRIPTION (provided by applicant): Vascular inflammation is a critical contributing factor to the development of atherosclerosis. Combined with the effects of lipid deposition, inflammation promotes endothelial dysfunction, smooth muscle proliferation, and matrix destabilization, adverse events that exacerbate developing atherosclerotic lesions and may ultimate lead to their rupture and to vessel thrombosis. The sources of inflammation are varied, but among the most important are the circulating substances that stimulate G protein-coupled receptors (GPCRs) present on the surface of endothelial cells. These include a diverse array of peptide ligands, amines, glycoproteins and enzymes. The activated receptors then relay intracellular signals by stimulating multiple pathways, including those for ERK, Akt, JNK, p38MAPK, and STAT, but activation of the NF-kB transcription factor has been deemed one of the most important and potent pro-inflammatory signals. We have uncovered a signal transduction pathway that mediates NF-kB activation in response to the GPCR agonists, Angiotensin II and thrombin. This pathway centers on the assembly of a multiprotein signaling module composed of the molecules CARMA3, Bcl10, and MALT1, which we now refer to as the "CBM signalosome". In this signalosome, the MALT1 protein acts as the primary effector, coordinating downstream stimulation of the canonical NF-kB machinery. It appears that this CBM signalosome is also critical for NF-kB activation induced by GPCRs that recognize lsyophosphatidic acid (LPA), IL-8, endothelin-1, and SDF-1/CXCL12. Most of these substances have been clearly linked to vascular dysfunction, inflammation, and atherogenesis, and it is thought that their ability to activate NF-kB is central to these pathophysiologic responses. Thus, we believe the CBM signalosome is a mechanistic hub responsible for relaying proinflammatory signals in the vessel wall, since it is stimulated by such a diverse array of GPCR agonists. As such, targeting the actions of the signalosome may prove to be a highly effective strategy for managing atherogenesis. In this proposal, we will probe the mechanistic links between the CBM signalosome and specific aspects of vascular pathobiology. This will be accomplished through three specific aims that (1) investigate the effect of blocking CBM activity on NF-kB activation in endothelial cells and novel aspects of endothelial pathophysiology, (2) explore the mechanisms whereby the CBM signalosome is assembled following GPCR activation, and (3) test the effect of blocking CBM activity on the atherogenic process in vivo. We anticipate that the results will broadly inform development of pharmaceutical strategies for curtailing the contributions of inflammation to atherogenesis.