Molloy C J, Taylor D S, Weber H
Department of Cardiovascular Biochemistry, Bristol-Myers Squibb Pharmaceutical Research Institute, Princeton, New Jersey 08543.
J Biol Chem. 1993 Apr 5;268(10):7338-45.
In cultured rat aortic smooth muscle cells, angiotensin II (AII) treatment led to increased tyrosine phosphorylation of cellular proteins with apparent molecular masses of 42, 44, 75, and 120 kDa, respectively, as assessed by antiphosphotyrosine immunoblotting. Increased protein tyrosine phosphorylation was observed within 1 min of AII addition and was maximal by 30 min. The overall pattern of AII-stimulated protein tyrosine phosphorylation was distinct from that observed following treatment of rat aortic smooth muscle cells with platelet-derived growth factor-BB. Specific antibodies were used to identify the AII-stimulated 42- and 44-kDa tyrosine-phosphorylated proteins as the "mitogen-activated protein kinases," p42mapk and p44mapk, respectively. Raf-1, a 70-74-kDa serine/threonine protein kinase, was not tyrosine-phosphorylated in response to AII but was found to be hyperphosphorylated as evidenced by retarded protein mobility in SDS gel analysis. Taken together, these data indicate that AII binding to vascular smooth muscle cells leads to rapid activation of a complex cascade of protein kinases, including protein kinase C, Raf-1, MAP kinases, and an undefined intracellular protein tyrosine kinase(s) that may be coordinately involved in signal transduction leading to cell proliferation.
在培养的大鼠主动脉平滑肌细胞中，用抗磷酸酪氨酸免疫印迹法评估发现，血管紧张素II（AII）处理导致细胞蛋白酪氨酸磷酸化增加，其表观分子量分别为42、44、75和120 kDa。在添加AII后1分钟内观察到蛋白酪氨酸磷酸化增加，30分钟时达到最大值。AII刺激的蛋白酪氨酸磷酸化的总体模式与用血小板衍生生长因子-BB处理大鼠主动脉平滑肌细胞后观察到的模式不同。使用特异性抗体将AII刺激的42 kDa和44 kDa酪氨酸磷酸化蛋白分别鉴定为“丝裂原活化蛋白激酶”，即p42mapk和p44mapk。Raf-1是一种70 - 74 kDa的丝氨酸/苏氨酸蛋白激酶，对AII无酪氨酸磷酸化反应，但在SDS凝胶分析中发现其蛋白迁移率减慢，表明其发生了过度磷酸化。综上所述，这些数据表明，AII与血管平滑肌细胞结合导致一系列蛋白激酶的快速激活，包括蛋白激酶C、Raf-1、丝裂原活化蛋白激酶以及一种未确定的细胞内蛋白酪氨酸激酶，它们可能共同参与导致细胞增殖的信号转导。
