Participation of PI3K and ERK1/2 pathways are required for human brain vascular smooth muscle cell migration

Abstract

Human brain vascular smooth muscle cell (HBVSMC) migration contributes to angiogenesis and several pathological processes in the brain. However, the molecular mechanism of angiogenesis, in which smooth muscle cell contributes, remains unclear. Our study investigates the role of vascular endothelial growth factor (VEGF) in the HBVSMC migration and elucidates the chemotactic signaling pathway mediating this action. We used the in vitro ‘scratch’ wound method to detect the HBVSMC migration. VEGF 165 (1–40 ng/ml) induced the HBVSMC migration in a dose-dependent manner ( P<0.05). VEGF 165 does not induce HBVSMC proliferation. Wortmannin, a specific phosphatidylinositol 3-kinase (PI3K) inhibitor, significantly inhibited serine/threonine kinase Akt/protein kinase B (PKB) phosphorylation and reduced HBVSMC migration into the wound edge following VEGF 165 stimulation ( P<0.05). PD98059, an extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitor, also significantly inhibited ERK1/2 phosphorylation and reduced the numbers of SMC migration. Parallel distance measurement showed that VEGF 165 induced HBVSMC migration significantly reduced due to inhibition of PI3K or ERK1/2 phosphorylation ( P<0.05). Our results demonstrate that VEGF 165 could induce HBVSMC migration but not proliferation in vitro. Inhibiting Akt/PKB or ERK1/2 phosphorylation could reduce VEGF 165 induced HBVSMC migration. We provide the first evidence that activation of PI3K or ERK1/2 pathways are a crucial event in VEGF 165 mediated signal transduction leading to HBVSMC migration.