Abstract：
Prolonged vasoconstrictor signalling found in hypertension, increases arterial contraction, and alters vessel architecture by stimulating arterial smooth muscle cell (ASMC) growth, underpinning the development of re-stenosis lesions and vascular remodelling. Vasoconstrictors interact with their cognate G protein coupled receptors activating a variety of signalling pathways to promote smooth muscle proliferation. Here, angiotensin II (AngII) and endothelin 1 (ET1), but not UTP stimulates ASMC proliferation. Moreover, siRNA-mediated depletion of endogenous GRK2 expression, or GRK2 inhibitors, compound 101 or paroxetine, prevented AngII and ET1-promoted ASMC growth. Depletion of GRK2 expression or inhibition of GRK2 activity ablated the prolonged phase of AngII and ET-stimulated ERK signalling, while enhancing and prolonging UTP-stimulated ERK signalling. Increased GRK2 expression enhanced and prolonged AngII and ET1-stimulated ERK signalling, but suppressed UTP-stimulated ERK signalling. In ASMC prepared from 6-week-old WKY and SHR, AngII and ET1-stimulated proliferation rates were similar, however, in cultures prepared from 12-week-old rats AngII and ET1-stimulated growth was enhanced in SHR-derived ASMC, which was reversed following depletion of GRK2 expression. Furthermore, in ASMC cultures isolated from 6-week-old WKY and SHR rats, AngII and ET1-stimulated ERK signals were similar, while in cultures from 12-week-old rats ERK signals were both enhanced and prolonged in SHR-derived ASMC, and were reversed to those seen in age-matched WKY-derived ASMC following pre-treatment of SHR-derived ASMC with compound 101. These data indicate that the presence of GRK2 and its catalytic activity are essential to enable pro-proliferative vasoconstrictors to promote growth via recruitment and activation of the ERK signalling pathway in ASMC.
摘要：
在高血压中发现的延长的血管收缩信号，增加动脉收缩，并通过刺激动脉平滑肌细胞（ASMC）生长来改变血管结构，支持再狭窄病变和血管重塑的发展。血管收缩剂与其同源G蛋白偶联受体相互作用，激活多种信号通路以促进平滑肌增殖。这里,血管紧张素II（AngII）和内皮素1（ET1），但UTP不刺激ASMC增殖。此外，siRNA介导的内源性GRK2表达消耗，或GRK2抑制剂，化合物101或帕罗西汀，阻止了AngII和ET1促进的ASMC生长。GRK2表达的减少或GRK2活性的抑制消除了AngII和ET刺激的ERK信号的延长阶段，同时增强和延长UTP刺激的ERK信号传导。GRK2表达增加增强和延长AngII和ET1刺激的ERK信号传导，但抑制了UTP刺激的ERK信号传导。在从6周大的WKY和SHR准备的ASMC中，AngII和ET1刺激的增殖率相似，然而,在由12周龄大鼠制备的培养物中，SHR衍生的ASMC中，AngII和ET1刺激的生长增强，在GRK2表达耗尽后逆转。此外，在从6周龄WKY和SHR大鼠分离的ASMC培养物中，AngII和ET1刺激的ERK信号相似，而在12周龄大鼠的培养物中，SHR衍生的ASMC中ERK信号既增强又延长，在用化合物101预处理SHR衍生的ASMC后，与年龄匹配的WKY衍生的ASMC中看到的结果相反。这些数据表明GRK2的存在及其催化活性对于使得促增殖性血管收缩剂能够通过ASMC中ERK信号通路的募集和活化来促进生长是必需的。
