Angiotensin II is a potent stimulator of MAP-kinase activity in neonatal rat cardiac fibroblasts.
Angiotensin II is a potent stimulator of MAP-kinase activity in neonatal rat cardiac fibroblasts.
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DOI：
10.1016/0022-2828(95)90051-9
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发表时间：
1995-05
影响因子：
5
通讯作者：
W. Schorb;K. Conrad;H. Singer;D. Dostal;K. Baker
中科院分区：
文献类型：
--
作者：
W. Schorb;K. Conrad;H. Singer;D. Dostal;K. Baker
我们以前已经表明，血管紧张素II（AII）是一种有丝分裂原新生大鼠心脏成纤维细胞。然而，导致成纤维细胞生长响应AII的信号事件仍有待阐明。促分裂原活化蛋白（MAP）激酶是细胞溶质丝氨酸/苏氨酸激酶，其已被证明在静止细胞中被不同的生长刺激物激活，从而与生长调节途径相关联。本研究的目的是确定是否MAP-激酶激活发生在响应AII/受体偶联在新生大鼠心脏成纤维细胞和MAP-激酶激活AII诱导的这些细胞的增殖中的作用。MAP-激酶亚型的免疫印迹分析显示，大鼠心脏成纤维细胞中主要为p44，p42 MAP-激酶较少。这两种亚型激活后，刺激细胞与AII为5分钟或血小板衍生生长因子-BB为10分钟。血管紧张素II刺激MAP-激酶的剂量依赖性的方式与EC 50为2.5 nm。用1 μ mAII MAP激酶刺激后2分钟，活性从90 ± 17.9增加到477.5 ± 75.9 pmol/min/mg蛋白，P<0.05，n = 4。在受体占据后的120-150分钟之间，观察到对AII的反应，MAP激酶活性从37.7 ± 5.3 pmol/min/mg蛋白质增加到110.9 ± 15.3 pmol/min/mg蛋白质，P<0.05，n = 4。AT 1受体拮抗剂EXP 3174可明显减弱对AII的反应。用卡巴胆碱刺激细胞诱导MAP-激酶活性的第一阶段，但不是第二阶段，并且该化合物对细胞生长没有影响。MAP-激酶活性的第二阶段在AII刺激后2-2.5小时，这些数据表明，2-3小时的受体与AII的占用是诱导DNA合成和成纤维细胞增殖所必需的。这些结果表明，AII刺激MAP-激酶的双相激活的AT 1受体，这一途径可能参与AII诱导的心脏成纤维细胞的促有丝分裂反应。
We have previously shown that angiotensin II (AII) is a mitogen for neonatal rat cardiac fibroblasts. However, the signaling events that lead to fibroblast cell growth in response to AII remain to be elucidated. Mitogen-activated protein (MAP) kinases are cytosolic serine/threonine kinases which have been shown to be activated in quiescent cells by diverse growth stimuli, thereby being linked to growth regulatory pathways. This study was designed to determine whether MAP-kinase activation occurred in response to AII/receptor coupling in neonatal rat cardiac fibroblasts and the role of MAP-kinase activation in the AII-induced proliferation of these cells. Immunoblot analysis of MAP-kinase isoforms revealed predominantly p44 with less p42 MAP-kinase in rat cardiac fibroblasts. Both isoforms were activated upon stimulation of the cells with AII for 5 min or platelet derived growth factor-BB for 10 min. Angiotensin II stimulated MAP-kinase in a dose-dependent fashion with an EC50of 2.5 nm. Two minutes following stimulation with 1 μm AII MAP-kinase activity increased from 90 ± 17.9 to 477.5 ± 75.9 pmol/min/mg protein, P<0.05, n = 4. A smaller, sustained, secondary increase in MAP-kinase activity from 37.7 ± 5.3 to 110.9 ± 15.3 pmol/min/mg protein, P<0.05, n = 4, was observed in response to AII between 120–150 minutes following receptor occupancy. The responses to AII were markedly attenuated by the AT1receptor antagonist EXP3174. Stimulation of the cells with carbachol induced the first but not the second phase of MAP-kinase activity and this compound had no effect on cellular growth. The second phase of MAP-kinase activity 2–2.5 h after AII stimulation, paralleled data demonstrating that a 2–3 h receptor occupancy with AII was necessary to induce DNA synthesis and fibroblast proliferation. These results indicate that AII stimulates a biphasic activation of MAP-kinase by the AT1receptor and that this pathway may participate in the AII induced mitogenic response in cardiac fibroblasts.