Activation of extracellular signal-regulated kinases (ERK1/2) by angiotensin II is dependent on c-Src in vascular smooth muscle cells.
Among the angiotensin II (Ang II)-mediated signal events likely to be important in vascular smooth muscle cells (VSMCs) is activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2). The upstream mediators by which Ang II activates ERK1/2 remain poorly defined. Recently, we showed that Ang II activated c-Src, a nonreceptor kinase, which is a candidate to mediate Ang II signal events. To determine whether c-Src is required for ERK1/2 activation by Ang II, we studied the effects of Src family-selective tyrosine kinase inhibitors on ERK1/2 activation and also studied Ang II-mediated signal events in Src-deficient and Src-overexpressing VSMCs. The tyrosine kinase inhibitors, genistein and CP-188,556, blocked Ang II-mediated ERK1/2 activation in rat VSMCs (rVSMCs). We derived Src-deficient VSMCs from the aortas of c-Src knockout mice (Src-/- mVSMCs). Basal ERK1/2 activity was lower, and activation of ERK1/2 by Ang II was significantly decreased in Src-/- mVSMCs compared with wild-type mVSMCs, whereas ERK1/2 protein expression and ERK1/2 activation by phorbol 12-myristate 13-acetate were similar. To examine the role of c-Src further, we overexpressed wild-type or dominant-negative c-Src in rVSMCs using retroviral vectors. ERK1/2 activation by Ang II was significantly increased in rVSMCs that overexpressed c-Src, whereas ERK1/2 activation by Ang II was significantly inhibited in rVSMCs that overexpressed dominant-negative c-Src compared with control rVSMCs. These findings demonstrate that c-Src activation is required for Ang II stimulation of ERK1/2 in VSMCs and suggest an important role for c-Src in Ang II-mediated signal transduction.
Ishida
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Department of Medicine, University of Washington, Seattle 98195, USA.
Ishida
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Thomas
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Berk
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D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000187:drug effects* / Q000378:metabolism*; D002478:Cells, Cultured / Q000187:drug effects / Q000201:enzymology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005822:Genetic Vectors; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000201:enzymology*; D009154:Mutation / Q000235:genetics / Q000502:physiology; D015688:Oncogene Protein pp60(v-src) / Q000235:genetics / Q000494:pharmacology*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D051381:Rats; D017207:Rats, Sprague-Dawley; D012190:Retroviridae / Q000235:genetics; D014162:Transfection; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D011505:Protein-Tyrosine Kinases; D015688:Oncogene Protein pp60(v-src); D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases