p63RhoGEF couples Gα(q/11)-mediated signaling to Ca2+ sensitization of vascular smooth muscle contractility.
p63RhoGEF couples Gα(q/11)-mediated signaling to Ca2+ sensitization of vascular smooth muscle contractility.
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DOI：
10.1161/circresaha.111.248898
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发表时间：
2011-10-14
影响因子：
20.1
通讯作者：
Somlyo AV
中科院分区：
文献类型：
--
作者：
Momotani K;Artamonov MV;Utepbergenov D;Derewenda U;Derewenda ZS;Somlyo AV
在正常和病变血管平滑肌（SM）中，RhoA通路通过G蛋白偶联受体（gpcr）被多种激动剂激活，在调节基底张力和外周阻力中起核心作用。这是通过抑制肌凝蛋白轻链磷酸酶发生的，导致肌凝蛋白调节轻链磷酸化增加。虽然人们认为特异性激动剂和gpcr可能与不同的RhoA鸟嘌呤核苷酸交换因子（gef）偶联，从而提高了选择性靶向特定gef用于治疗的可能性，但这一概念在很大程度上尚未被用于SM收缩。我们研究了p63RhoGEF是否在血管中作为RhoA激活的介质，以及它是否被Gαq/11偶联激动剂选择性激活。p63RhoGEF已知在体外特异性偶联Gαq/11。我们发现p63RhoGEF存在于SM组织中，并证明小鼠门静脉中内源性p63RhoGEF的沉默比主要由Gα12/13介导的血栓素类似物U46619更能抑制内皮素-1诱导的收缩力。这是因为内皮素-1作用于g - αq/11和g - α12/13。当使用苯肾上腺素作为激动剂时，将外源性分离的p63RhoGEF的pleckstrin-homology （PH）结构域（残基331-580）引入渗透的兔门静脉，可以抑制Ca2+敏化力和RhoA的激活。这加强了基于内皮素-1的结果，因为苯肾上腺素被认为只通过g - αq/11起作用。我们证明p63RhoGEF选择性地将Gαq/11偶联，而不是Gα12/13偶联，激活血管和培养细胞中的RhoA，从而介导Gαq/11偶联激动剂诱导的生理上重要的Ca2+致敏力。我们的研究结果表明，通过p63RhoGEF的信号传导为选择性调节血压提供了一种新的机制。
In normal and diseased vascular smooth muscle (SM), the RhoA pathway, which is activated by multiple agonists through G protein-coupled receptors (GPCRs), plays a central role in regulating basal tone and peripheral resistance. This occurs through inhibition of myosin light chain phosphatase, leading to increased phosphorylation of the myosin regulatory light chain. While it is thought that specific agonists and GPCRs may couple to distinct RhoA guanine nucleotide exchange factors (GEFs), thus raising the possibility of selective targeting of specific GEFs for therapeutic use, this notion is largely unexplored for SM contraction. We examine whether p63RhoGEF, known to couple specifically to Gαq/11 in vitro, is functional in blood vessels as a mediator of RhoA activation, and if it is selectively activated by Gαq/11 coupled agonists. We find that p63RhoGEF is present across SM tissues and demonstrate that silencing of the endogenous p63RhoGEF in mouse portal vein inhibits contractile force induced by endothelin-1 to a greater extent than the predominantly Gα12/13 mediated thromboxane analogue, U46619. This is because endothelin-1 acts on Gαq/11 as well as Gα12/13. Introduction of the exogenous isolated pleckstrin-homology (PH) domain of p63RhoGEF (residues 331–580) into permeabilized rabbit portal vein inhibited Ca2+ sensitized force and activation of RhoA, when phenylephrine was used as an agonist. This reinforces the results based on endothelin-1, because phenylephrine is thought to act exclusively through Gαq/11. We demonstrate that p63RhoGEF selectively couples Gαq/11, but not Gα12/13, to RhoA activation in blood vessels and cultured cells, and thus mediates the physiologically important Ca2+ sensitization of force induced with Gαq/11 coupled agonists. Our results suggest that signaling through p63RhoGEF provides a novel mechanism for selective regulation of blood pressure.