Angiotensin II induces migration and Pyk2/paxillin phosphorylation of human monocytes

Angiotensin (Ang) II has been shown to enhance the development of atheroscl erotic lesions. Migration of monocytes is an early critical step in the ath erosclerotic process. To elucidate mechanisms by which Ang II promotes athe rogenesis, we investigated its effects on human monocyte migration. Ang II induced migration of human peripheral blood monocytes (HPBM) and human THP- 1 monocytes at concentrations between 0.01 and 1 mu mol/L, with a 3.6+/-0.6 -fold induction in HPBM and a 4.8+/-0.9-fold induction in THP-1 cells at 1 mu mol/L Ang II (both P<0.01 versus unstimulated cells). Addition of the An g II receptor type 1 (AT1-R) antagonist losartan (1 to 100 <mu>mol/L) suppr essed Ang II-induced migration of HPBM and THP-1 monocytes in a dose-depend ent manner, demonstrating an AT1-R-mediated mechanism, Ang II-directed migr ation was also blocked by the Src kinase inhibitor PP2 (10 mu mol/L), by th e extracellular-regulated protein kinase (ERK 1/2) inhibitor PD98059 (30 mu mol/L), and by the p38-MAPK inhibitor SB203580 (10 mu mol/L), indicating t hat Src, ERK 1/2, and p38 are all involved in Ang II-induced migration of H PBM and human THP-1 monocytes, The proline-rich tyrosine kinase 2 (Pyk2) an d paxillin are 2 cytoskeleton-associated proteins involved in cell movement , phosphorylated by Ang II in other cell types, and abundantly expressed in monocytes. Ang II (1 mu mol/L) induced Pyk2 and paxillin phosphorylation i n human THP-1 monocytes, peaking after 10 minutes for Pyk2 with a 6.7+/-0.9 -fold induction and after 2 minutes for paxillin with a 3.2+/-0.4-fold indu ction. Ang II-induced phosphorylation of both proteins was suppressed by lo sartan and the Src inhibitor PP2, whereas no effect was observed with PD980 59 and SB203580, This study demonstrates a novel proatherogenic action of A ng II on human monocytes by stimulating their migration, through an AT1-R-d ependent process, involving signaling through Src, ERK 1/2, and p38. Furthe rmore, the promigratory actions of Ang II in human monocytes are associated with the phosphorylation of 2 cytoskeleton-associated proteins, Pyk2 and p axillin.