title: VEGF-induced endothelial cell migration requires urokinase receptor (uPAR)-dependent integrin redistribution.
abstract: OBJECTIVE
  Vascular endothelial growth factor (VEGF)-initiated angiogenesis requires coordinated proteolytic degradation of extracellular matrix provided by the urokinase plasminogen activator/urokinase receptor (uPA/uPAR) system and regulation of cell migration provided by integrin-matrix interaction. In this study, we investigated the mechanisms underlying the uPAR-dependent modulation of VEGF-induced endothelial migration.
  
  
  RESULTS
  We used flow cytometry to quantify integrins at the cell surface. Stimulation of human and murine endothelial cells with VEGF resulted in internalization of α5β1-integrins. Micropatterning and immunocytochemistry revealed co-clustering of uPAR and α5β1-integrins and retrieval via clathrin-coated vesicles. It was also contingent on receptors of the low-density lipoprotein receptor (LDL-R) family. VEGF-induced integrin redistribution was inhibited by elimination of uPAR from the endothelial cell surface or by inhibitory peptides that block the uPAR-integrin interaction. Under these conditions, the migratory response of endothelial cells upon VEGF stimulation was impaired both in vitro and in vivo.
  
  
  CONCLUSIONS
  The observations indicate that uPAR is an essential component of the network through which VEGF controls endothelial cell migration. uPAR is a bottleneck through which the VEGF-induced signal must be funnelled for both focused proteolytic activity at the leading edge and for redistribution of integrins.
authors.affiliation: Institute of Vascular Biology and Thrombosis Research, Vienna A-1090,  Austria.
authors.forename: Revu Ann
authors.initials: RA
authors.lastname: Alexander
authors.forename: Gerald W
authors.initials: GW
authors.lastname: Prager
authors.forename: Judit
authors.initials: J
authors.lastname: Mihaly-Bison
authors.forename: Pavel
authors.initials: P
authors.lastname: Uhrin
authors.forename: Stefan
authors.initials: S
authors.lastname: Sunzenauer
authors.forename: Bernd R
authors.initials: BR
authors.lastname: Binder
authors.forename: Gerhard J
authors.initials: GJ
authors.lastname: Schütz
authors.forename: Michael
authors.initials: M
authors.lastname: Freissmuth
authors.forename: Johannes M
authors.initials: JM
authors.lastname: Breuss
mesh_terms: D000818:Animals; D002465:Cell Movement; D002478:Cells, Cultured; D022163:Clathrin-Coated Vesicles / Q000378:metabolism; D004705:Endocytosis; D042783:Endothelial Cells / Q000378:metabolism*; D005434:Flow Cytometry; D061307:Human Umbilical Vein Endothelial Cells / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D039081:Integrin alpha5beta1 / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D018919:Neovascularization, Physiologic; D021381:Protein Transport; D034622:RNA Interference; D011973:Receptors, LDL / Q000378:metabolism; D055293:Receptors, Urokinase Plasminogen Activator / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
chemical_list: D039081:Integrin alpha5beta1; C524898:PLAUR protein, human; C524899:Plaur protein, mouse; D011973:Receptors, LDL; D055293:Receptors, Urokinase Plasminogen Activator; D011994:Recombinant Proteins; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse