Vascular endothelial growth factor activates nuclear factor-kappa B and induces monocyte chemoattractant protein-1 in bovine retinal endothelial cells

Vascular endothelial growth factor (VEGF) has been suggested to play a role in the pathogenesis of diabetic vascular complications. In the present stu dy, we investigated whether expression of monocyte chemoattractant protein- 1 (MCP-1), a chemokine that has been proposed to recruit leukocytes to site s of inflammation, neovascularization, and vascular injury, can be modulate d by VEGF in bovine retinal microvascular endothelial cells (BRECs). VEGF i nduced expression of MCP-1 mRNA in BRECs in a concentration- and time-depen dent manner. Secretion of MCP-1 into the culture medium of BRECs treated wi th VEGF for 24 h was increased by 2.2-fold compared with the control. Inhib itors of transcription factor NF-kappa B, N-alpha-tosyl-L-lysine chlorometh ylketone (TLCK) and N-acetylcysteine (NAC), as well as an inhibitor of the extracellular signal-regulated kinase (ERK) pathway, PD 98059, attenuated V EGF-induced expression of MCP-1 mRNA. Using electrophoretic gel mobility sh ift assay, we observed that VEGF stimulated binding activity of NF-kappa B. VEGF-induced NF-kappa B activation was inhibited by TLCK and NAC, but not by PD 98059. Binding activity of transcription factor AP-1, which is sugges ted to regulate induction of the MCP-1 gene together with NF-kappa B, was a lso stimulated by VEGF. PD 98059 inhibited the VEGF-induced activation of A P-1. These results indicate that VEGF induces MCP-1 expression in BRECs mos t likely by activating NF-kappa B and AP-1 via ERK-independent and -depende nt pathways. Activation of NF-kappa B and induction of MCP-1 by VEGF in mic rovascular endothelial cells may contribute to the development of diabetic vascular complications.