title: Transactivation of vascular endothelial growth factor (VEGF) receptor Flk-1/KDR is involved in sphingosine 1-phosphate-stimulated phosphorylation of Akt and endothelial nitric-oxide synthase (eNOS).
abstract: Sphingosine 1-phosphate (S1P) and vascular endothelial growth factor (VEGF) elicit numerous biological responses including cell survival, growth, migration, and differentiation in endothelial cells mediated by the endothelial differentiation gene, a family of G-protein-coupled receptors, and fetal liver kinase-1/kinase-insert domain-containing receptor (Flk-1/KDR), one of VEGF receptors, respectively. Recently, it was reported that S1P or VEGF treatment of endothelial cells leads to phosphorylation at Ser-1179 in bovine endothelial nitric oxide synthase (eNOS), and this phosphorylation is critical for eNOS activation. S1P stimulation of eNOS phosphorylation was shown to involve G(i) protein, phosphoinositide 3-kinase, and Akt. VEGF also activates eNOS through Flk-1/KDR, phosphoinositide 3-kinase, and Akt, which suggested that S1P and VEGF may share upstream signaling mediators. We now report that S1P treatment of bovine aortic endothelial cells acutely increases the tyrosine phosphorylation of Flk-1/KDR, similar to VEGF treatment. S1P-mediated phosphorylation of Flk-1/KDR, Akt, and eNOS were all inhibited by VEGF receptor tyrosine kinase inhibitors and by antisense Flk-1/KDR oligonucleotides. Our study suggests that S1P activation of eNOS involves G(i), calcium, and Src family kinase-dependent transactivation of Flk-1/KDR. These data are the first to establish a critical role of Flk-1/KDR in S1P-stimulated eNOS phosphorylation and activation.
authors.affiliation: Center for Cardiovascular Research, University of Rochester, Rochester, New York 14642, USA.
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Tanimoto
authors.forename: Zheng-Gen
authors.initials: ZG
authors.lastname: Jin
authors.forename: Bradford C
authors.initials: BC
authors.lastname: Berk
mesh_terms: D000818:Animals; D001011:Aorta; D001483:Base Sequence; D002417:Cattle; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D016228:Endothelial Growth Factors / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology*; D007700:Kinetics; D008222:Lymphokines / Q000494:pharmacology*; D008246:Lysophospholipids; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D015533:Transcriptional Activation; D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics* / Q000378:metabolism; D042442:Vascular Endothelial Growth Factors
chemical_list: D016228:Endothelial Growth Factors; D019204:GTP-Binding Proteins; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines; D008246:Lysophospholipids; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D020319:Oligodeoxyribonucleotides, Antisense; 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; D040301:Vascular Endothelial Growth Factor Receptor-2; D042442:Vascular Endothelial Growth Factors; C060506:sphingosine 1-phosphate