Bouallegue Ali, Daou Grace Bou, Srivastava Ashok K
Laboratory of Cell Signaling, Montreal Diabetes Research Centre, Centre de Recherche, Centre Hospitalier de l'Université de Montréal, Technopole Angus Campus, and Department of Medicine, University of Montreal, Montreal, Quebec, Canada.
Am J Physiol Heart Circ Physiol. 2007 Oct;293(4):H2072-9. doi: 10.1152/ajpheart.01097.2006. Epub 2007 Jul 20.
Nitric oxide (NO), in addition to its vasodilator action, has also been shown to antagonize the mitogenic and hypertrophic responses of growth factors and vasoactive peptides such as endothelin-1 (ET-1) in vascular smooth muscle cells (VSMCs). However, the mechanism by which NO exerts its antimitogenic and antihypertrophic effect remains unknown. Therefore, the aim of this study was to determine whether NO generation would modify ET-1-induced signaling pathways involved in cellular growth, proliferation, and hypertrophy in A-10 VSMCs. Treatment of A-10 VSMCs with S-nitroso-N-acetylpenicillamine (SNAP) or sodium nitroprusside (SNP), two NO donors, attenuated the ET-1-enhanced phosphorylation of several key components of growth-promoting and hypertrophic signaling pathways such as ERK1/2, PKB, and Pyk2. On the other hand, inhibition of the endogenous NO generation with N(G)-nitro-L-arginine methyl ester, a nitric oxide synthase inhibitor, increased the ET-1-induced phosphorylation of these signaling components. Since NO mediates its effect principally through a cGMP-soluble guanylyl cyclase (sGC) pathway, we investigated the role of these molecules in NO action. 8-Bromoguanosine 3',5'-cyclic monophosphate, a nonmetabolizable and cell-permeant analog of cGMP, exhibited a effect similar to that of SNAP and SNP. Furthermore, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), an inhibitor of sGC, reversed the inhibitory effect of NO on ET-1-induced responses. SNAP treatment also decreased the protein synthesis induced by ET-1. Together, these data demonstrate that NO, in a cGMP-dependent manner, attenuated ET-1-induced phosphorylation of ERK1/2, PKB, and Pyk2 and also antagonized the hypertrophic effects of ET-1. It may be suggested that NO-induced generation of cGMP contributes to the inhibition of ET-1-induced mitogenic and hypertrophic responses in VSMCs.
一氧化氮（NO）除了具有血管舒张作用外，还被证明可拮抗血管平滑肌细胞（VSMC）中生长因子和血管活性肽（如内皮素-1，ET-1）的促有丝分裂和肥大反应。然而，NO发挥其抗有丝分裂和抗肥大作用的机制尚不清楚。因此，本研究的目的是确定NO的生成是否会改变ET-1诱导的参与A-10 VSMC细胞生长、增殖和肥大的信号通路。用两种NO供体S-亚硝基-N-乙酰青霉胺（SNAP）或硝普钠（SNP）处理A-10 VSMC，可减弱ET-1增强的生长促进和肥大信号通路中几个关键成分（如ERK1/2、PKB和Pyk2）的磷酸化。另一方面，用一氧化氮合酶抑制剂N(G)-硝基-L-精氨酸甲酯抑制内源性NO生成，可增加ET-1诱导的这些信号成分的磷酸化。由于NO主要通过cGMP-可溶性鸟苷酸环化酶（sGC）途径介导其作用，我们研究了这些分子在NO作用中的作用。8-溴鸟苷3',5'-环一磷酸是一种不可代谢且可透过细胞的cGMP类似物，其作用与SNAP和SNP相似。此外，sGC抑制剂1H-[1,2,4]恶二唑并[4,3-a]喹喔啉-1-酮（ODQ）可逆转NO对ET-1诱导反应的抑制作用。SNAP处理还可降低ET-1诱导的蛋白质合成。总之，这些数据表明，NO以cGMP依赖的方式减弱ET-1诱导的ERK1/2、PKB和Pyk2的磷酸化，并且还拮抗ET-1的肥大作用。可以推测，NO诱导的cGMP生成有助于抑制VSMC中ET-1诱导的有丝分裂和肥大反应。
