Abstract
Angiotensin II (Ang II) stimulates protein synthesis by activating spleen tyrosine kinase (Syk), and DNA synthesis through epidermal growth factor receptor (EGFR) transactivation in vascular smooth muscle cells (VSMCs). This study was conducted to determine if Syk mediates Ang II-induced migration of aortic VSMCs using a scratch wound approach. Treatment with Ang II (200nM) for 24 h increased by 1.56 ± 0.14 fold VSMC migration. Ang II-induced VSMC migration, and Syk phosphorylation as determined by Western blot analysis, were minimized by Syk inhibitor piceatannol (10μM), and by transfecting VSMCs with dominant negative but not wild type Syk plasmid. Ang II-induced VSMC migration and Syk phosphorylation were attenuated by inhibitors of c-Src (PP2), p38 MAPK (SB202190) and ERK1/2 (U0126). SB202190 attenuated p38 MAPK and c-Src but not ERK1/2 phosphorylation indicating that p38 MAPK acts upstream of c-Src and Syk. c-Src inhibitor PP2 attenuated Syk and ERK1/2 phosphorylation suggesting that c-Src acts upstream of Syk and ERK1/2. Ang II- and EGF-induced VSMC migration and EGFR phosphorylation were inhibited by the EGFR blocker AG1478 (2μM). Neither the Syk inhibitor piceatannol nor the dominant negative Syk mutant altered EGF-induced cell migration or Ang II- and EGF-induced EGFR phosphorylation. c-Src inhibitor PP2 diminished EGF-induced VSMC migration and EGFR, ERK1/2 and p38 MAPK phosphorylation. ERK1/2 inhibitor U0126 (10μM) attenuated EGF-induced cell migration, and ERK1/2 but not EGFR phosphorylation. These data suggest that Ang II stimulates VSMC migration via p38 MAPK activated c-Src through Syk, and via EGFR transactivation through ERK1/2 and partly p38 MAPK.
Footnotes
- Received June 15, 2009.
- Revision received September 28, 2009.
- Accepted September 29, 2009.
- The American Society for Pharmacology and Experimental Therapeutics