title: Roles of reactive oxygen species in angiopoietin-1/tie-2 receptor signaling.
abstract: In this study we identified the involvement of reactive oxygen species (ROS) in signaling and biological effects of the angiopoietin-1 (Ang-1)/tie-2 receptor pathway. Exposure of human umbilical vein endothelial cells to Ang-1 (50 ng/ml) induced rapid and transient production of ROS, particularly superoxide anions. ROS production was attenuated by preincubation with a peptide (gp91ds-tat) that inhibits the association of the gp91(phox) subunit with the p47(phox) subunit of NADPH oxidase and by the expression of a dominant-negative form of Rac-1 (Rac1N17). These results suggest that ROS production in response to Ang-1 exposure originates mainly from a Rac-1-dependent NADPH oxidase. Overexpression of antioxidants (superoxide dismutase and catalase) and Rac1N17, as well as preincubation with selective inhibitors of NADPH oxidase augmented basal p38 phosphorylation, inhibited Ang-1-induced PAK-1 phosphorylation and potentiated Ang-1-induced Erk1/2 phosphorylation but had no influence on AKT and SAPK/JNK phosphorylation by Ang-1. Exposure to Ang-1 (100 ng/ml) for 5 h induced a threefold increase in endothelial cell migration, a response that was strongly inhibited by overexpression of antioxidants, Rac1N17, and selective NADPH oxidase inhibitors. We conclude that activation of tie-2 receptors by Ang-1 triggers the production of ROS through activation of NADPH oxidase and that ROS generation by Ang-1 promotes endothelial cell migration while negatively regulating Erk1/2 phosphorylation.
authors.affiliation: Critical Care and Respiratory Divisions, Royal Victoria Hospital and Meakins-Christie Laboratories, McGill University, Montreal, Québec, Canada.
authors.forename: Rania
authors.initials: R
authors.lastname: Harfouche
authors.forename: Nelly Abdel
authors.initials: NA
authors.lastname: Malak
authors.forename: Ralf P
authors.initials: RP
authors.lastname: Brandes
authors.forename: Aly
authors.initials: A
authors.lastname: Karsan
authors.forename: Kaikobad
authors.initials: K
authors.lastname: Irani
authors.forename: Sabah N A
authors.initials: SN
authors.lastname: Hussain
mesh_terms: D000166:Acridines / Q000378:metabolism; D042683:Angiopoietin-1 / Q000378:metabolism*; D042682:Angiopoietins / Q000378:metabolism; D000975:Antioxidants / Q000737:chemistry / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D002465:Cell Movement; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology; D004730:Endothelium, Vascular / Q000166:cytology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D005799:Genes, Dominant; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D008562:Membrane Glycoproteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D017382:Reactive Oxygen Species; D042787:Receptor, TIE-2 / Q000378:metabolism*; D015398:Signal Transduction; D013482:Superoxide Dismutase / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D014471:Umbilical Veins / Q000166:cytology; D054462:p21-Activated Kinases; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D000166:Acridines; D042683:Angiopoietin-1; D042682:Angiopoietins; D000975:Antioxidants; D004791:Enzyme Inhibitors; D008562:Membrane Glycoproteins; D010455:Peptides; D010750:Phosphoproteins; D017382:Reactive Oxygen Species; D049452:Green Fluorescent Proteins; C033472:10,10'-dimethyl-9,9'-biacridinium; D002374:Catalase; D013482:Superoxide Dismutase; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D042787:Receptor, TIE-2; C515903:PAK1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D054462:p21-Activated Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases