title: Role of PI 3-kinase in angiopoietin-1-mediated migration and attachment-dependent survival of endothelial cells.
abstract: Angiopoietin-1 is a unique growth factor which induces Tie2 receptor autophosphorylation and interaction with signal transduction molecules, GRB2 and p85 subunit of PI 3-kinase, but no detectable mitogenic response. Here we show that PI 3-kinase-dependent activation of Akt and attachment to extracellular matrix are required for angiopoietin-1-mediated endothelial cell survival. Apoptosis of growth factor-deprived cells grown in monolayer was decreased by angiopoietin-1 and correlated with Akt activation. In contrast, angiopoietin-1, bFGF or VEGF failed to protect cells in suspension culture. Ceramide, an intermediate of several apoptotic pathways, interferes with growth factor-mediated Akt activation. Ceramide induced endothelial cell death and abolished angiopoietin-1-mediated activation of Akt and the effect on cell survival. In addition, we found that PI 3-kinase activity is necessary for migration of endothelial cells in response to Angiopoietin-1. A transient activation of MAPK/ERKs was also detected within 10 min after stimulation with angiopoietin-1. In contrast to VEGF-mediated biological effects, inhibition of MAPK/ERKs by PD98059 in endothelial cells did not affect angiopoietin-1 mediated survival or migration. These findings indicate significant differences in intracellular signaling between VEGF and angiopoietin-1 and that PI 3-kinase lipid products are key mediators of the biological effects of angiopoietin-1.
authors.affiliation: Department of Medicine, St. Elizabeth's Medical Center, Tufts University School of Medicine, 736 Cambridge Street, Boston, Massachusetts 02135, USA.
authors.forename: K
authors.initials: K
authors.lastname: Fujikawa
authors.forename: I
authors.initials: I
authors.lastname: de Aos Scherpenseel
authors.forename: S K
authors.initials: SK
authors.lastname: Jain
authors.forename: E
authors.initials: E
authors.lastname: Presman
authors.forename: R A
authors.initials: RA
authors.lastname: Christensen
authors.forename: L
authors.initials: L
authors.lastname: Varticovski
mesh_terms: D042683:Angiopoietin-1; D017209:Apoptosis / Q000502:physiology; D002448:Cell Adhesion / Q000502:physiology; D002465:Cell Movement / Q000502:physiology*; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002867:Chromones / Q000494:pharmacology; D016228:Endothelial Growth Factors / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology* / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D006801:Humans; D008222:Lymphokines / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D013110:Sphingosine / Q000031:analogs & derivatives / Q000494:pharmacology; D014471:Umbilical Veins / Q000166:cytology; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
chemical_list: D042683:Angiopoietin-1; D002867:Chromones; D016228:Endothelial Growth Factors; D004791:Enzyme Inhibitors; D016222:Fibroblast Growth Factor 2; D008222:Lymphokines; D008562:Membrane Glycoproteins; D020928:Mitogen-Activated Protein Kinases; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D013110:Sphingosine; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; C064769:N-acetylsphingosine; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C494918:AKT1 protein, human