title: VEGF-induced paracellular permeability in cultured endothelial cells involves urokinase and its receptor.
abstract: Vascular endothelial growth factor/vascular permeability factor (VEGF) has been implicated in blood/tissue barrier dysfunctions associated with pathological angiogenesis, but the mechanisms of VEGF-induced permeability increase are poorly understood. Here, the role of VEGF-induced extracellular proteolytic activities on the endothelial cell permeability increase is evaluated. Confluent monolayers of bovine retinal microvascular endothelial (BRE) cells grown on porous membrane were treated with VEGF or urokinase plasminogen activator (uPA), and permeability changes were analyzed. uPA-induced permeability was rapid and sustained, but VEGF-induced permeability showed a biphasic pattern: a rapid and transient phase (1-2 h) followed by delayed and sustained phase (6-24 h). The delayed, but not the early phase of VEGF-induced permeability, was blocked by anti-uPA or anti-uPAR (uPA receptor) antibodies and was accompanied by reduced transendothelial electrical resistance, indicating the paracellular route of permeability. Confocal microscopy and Western blotting showed that VEGF treatment increased free cytosolic beta-catenin, which was followed by beta-catenin nuclear translocation, upregulation of uPAR, and downregulation of occludin. Membrane-bound occludin was released immediately after uPA treatment, but with a long delay after VEGF treatment, suggesting a requirement for uPAR gene expression. In conclusion, VEGF induces a sustained paracellular permeability in capillary endothelial cells that is mediated by activation of the uPA/uPAR system.
authors.affiliation: Vascular Biology Center, Department of Pharmacology & Toxicology, Medical College of Georgia, 1120 15th Street, Augusta, Georgia 30912, USA. abehzadi@mail.mcg.edu
authors.forename: M Ali
authors.initials: MA
authors.lastname: Behzadian
authors.forename: L Jack
authors.initials: LJ
authors.lastname: Windsor
authors.forename: Nagla
authors.initials: N
authors.lastname: Ghaly
authors.forename: Gregory
authors.initials: G
authors.lastname: Liou
authors.forename: Nai-Tse
authors.initials: NT
authors.lastname: Tsai
authors.forename: Ruth B
authors.initials: RB
authors.lastname: Caldwell
mesh_terms: D000818:Animals; D002417:Cattle; D002463:Cell Membrane Permeability / Q000187:drug effects*; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000493:pharmacokinetics; D016228:Endothelial Growth Factors / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology*; D008222:Lymphokines / Q000494:pharmacology*; D008565:Membrane Proteins / Q000493:pharmacokinetics; D018613:Microscopy, Confocal; D062793:Occludin; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000502:physiology*; D055293:Receptors, Urokinase Plasminogen Activator; D015534:Trans-Activators / Q000493:pharmacokinetics; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D051176:beta Catenin
chemical_list: D003598:Cytoskeletal Proteins; D016228:Endothelial Growth Factors; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines; D008565:Membrane Proteins; D062793:Occludin; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D015534:Trans-Activators; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D051176:beta Catenin; D014568:Urokinase-Type Plasminogen Activator