B-Arrestins and GPCR Kinases in Vascular Function/Growth

性状（由申请方提供）：G蛋白偶联受体（GPCR），包括儿茶酚胺和血管紧张素II的受体，调节血管反应性，包括血管收缩和血管舒张，以及血管平滑肌（VSM）细胞有丝分裂和迁移。血管反应性可能在高血压中受到干扰，而改变的VSM有丝分裂和迁移表征了外科搭桥术后的病理性内膜增生或动脉血管成形术后的再狭窄。在GPCR激活后，GPCR被七种GPCR激酶（GRK）之一磷酸化，然后b-抑制蛋白的两种亚型之一被募集到受体。b-抑制蛋白结合在空间上阻断了G蛋白的进一步信号传导，导致受体脱敏和信号传导的减弱。β-抑制蛋白还在信号传导中发挥积极作用，作为衔接子和支架来组织GPCR介导的MAP激酶级联激活，例如细胞外信号调节激酶（ERK 1/2）。这些MAP激酶调节VSM细胞和其他细胞类型的有丝分裂和迁移。我们的研究小组已经培育出了GRKs和b-抑制蛋白分别被敲除的小鼠。我们将利用这些动物，和VSM细胞，从他们测试的核心假设，即调节GPCR信号的b-抑制蛋白和GRKs是至关重要的正常血管稳态。我们的具体目标是：1）通过分析清醒和麻醉状态下的血压反应和离体主动脉环的血管反应性，阐明b-arrestin和GRK基因敲除小鼠的血管表型; 2）通过测定A）b-抑制蛋白和GRK的特异性，抑制蛋白和GRKs在通过内源性GPCR使第二信使信号脱敏中的作用，和B）b-抑制蛋白和GRKs在GPCR刺激的VSM细胞的ERK活化、增殖和迁移中的作用;和3）确定特异性b-抑制蛋白或GRKs的丧失是否改变小鼠静脉移植手术或动脉损伤后的体内增殖性内膜增生。这些实验有可能导致限制静脉移植失败和再狭窄的新策略的发展。

DESCRIPTION (provided by the applicant): G protein-coupled receptors (GPCRs) including those for catecholamines and angiotensin II regulate vascular reactivity, including vasoconstriction and vasodilation, as well as vascular smooth muscle (VSM) cell mitogenesis and migration. Vascular reactivity may be perturbed in hypertension, whereas altered VSM mitogenesis and migration characterize pathological intimal hyperplasia following surgical bypass or restenosis after arterial angioplasty. Following GPCR activation, GPCRs are phosphorylated by one of seven GPCR kinases (GRKs) and then one of two isoforms of b-arrestin is recruited to the receptor. b-arrestin binding sterically interdicts further signaling to G proteins, leading to receptor desensitization and attenuation of signaling. b-arrestins also play positive roles in signaling, serving as adapters and scaffolds to organize GPCR- mediated activation of MAP kinase cascades, such as the extracellular signal regulated kinases (ERK 1/2). These MAP kinases regulate mitogenesis and migration of VSM cells and other cell types. Our group has developed mice in which the GRKs and b-arrestins have been individually knocked out. We will utilize these animals, and VSM cells from them, to test the central hypothesis that regulation of GPCR signaling by b-arrestins and GRKs is critical for normal vascular homeostasis. Our specific aims are 1) To elucidate the vascular phenotype of b-arrestin and GRK knockout mice by analyzing conscious and anesthetized blood pressure responses and vascular reactivity using isolated aortic rings; 2) To elucidate the roles of b-arrestins and GRKs in signaling via endogenous GPCRs in isolated arterial and venous VSM cells from wild type and knockout mice by determining both A) the specificity of b-arrestins and GRKs in desensitizing second messenger signaling via endogenous GPCRs and B) the roles of b-arrestins and GRKs in GPCR stimulated ERK activation, proliferation, and migration of VSM cells; and 3) To determine if the loss of specific b-arrestins or GRKs alters in vivo proliferative intimal hyperplasia following mouse vein-graft surgery or arterial injury. These experiments have the potential to lead to the development of new strategies for limiting vein graft failure and restenosis.