pai-039 and Ischemia

Plasminogen activator inhibitor-1 (PAI-1) regulates angiogenesis via effects on extracellular matrix proteolysis and cell adhesion. However, no previous study has implicated PAI-1 in controlling vascular endothelial growth factor (VEGF) signaling. We tested the hypothesis that PAI-1 downregulates VEGF receptor-2 (VEGFR-2) activation by inhibiting a vitronectin-dependent cooperative binding interaction between VEGFR-2 and αVβ3.. We studied effects of PAI-1 on VEGF signaling in human umbilical vein endothelial cells. PAI-1 inhibited VEGF-induced phosphorylation of VEGFR-2 in human umbilical vein endothelial cells grown on vitronectin, but not on fibronectin or collagen. PAI-1 inhibited the binding of VEGFR-2 to β3 integrin, VEGFR-2 endocytosis, and intracellular signaling pathways downstream of VEGFR-2. The anti-VEGF effect of PAI-1 was mediated by 2 distinct pathways, one requiring binding to vitronectin and another requiring binding to very low-density lipoprotein receptor. PAI-1 inhibited VEGF-induced angiogenesis in vitro and in vivo, and pharmacological inhibition of PAI-1 promoted collateral arteriole development and recovery of hindlimb perfusion after femoral artery interruption.. PAI-1 inhibits activation of VEGFR-2 by VEGF by disrupting a vitronectin-dependent proangiogenic binding interaction involving αVβ3 and VEGFR-2. These results broaden our understanding of the roles of PAI-1, vitronectin, and endocytic receptors in regulating VEGFR-2 activation and suggest novel therapeutic strategies for regulating VEGF signaling.

Topics: Animals; Cell Adhesion; Cell Movement; Cells, Cultured; Disease Models, Animal; Endocytosis; Endothelial Cells; Hindlimb; Human Umbilical Vein Endothelial Cells; Humans; Indoleacetic Acids; Integrin alphaVbeta3; Ischemia; Male; Mice, Inbred C57BL; Mice, Knockout; Muscle, Skeletal; Mutation; Neovascularization, Physiologic; Phosphorylation; Plasminogen Activator Inhibitor 1; Receptor Cross-Talk; Receptors, LDL; Recombinant Proteins; RNA Interference; Serine Proteinase Inhibitors; Signal Transduction; Time Factors; Transfection; Vascular Endothelial Growth Factor Receptor-2; Vitronectin