title: The presence of a single tyrosine residue at the carboxyl domain of vascular endothelial growth factor receptor-2/FLK-1 regulates its autophosphorylation and activation of signaling molecules.
abstract: Vascular endothelial growth factor receptor (VEGFR)-2 plays a critical role in vasculogenesis during embryonic development and pathological angiogenesis, but little is known about the molecular mechanisms governing its functions. Here we investigated the role of tyrosine 1212 on mouse VEGFR-2 autophosphorylation and its signal transduction relay in endothelial cells. Mutation of tyrosine 1212 on VEGFR-2 to phenylalanine severely impaired the ligand-dependent autophosphorylation of VEGFR-2 and its ability to associate with and activate Src. This mutation also reduced the VEGFR-2 ability to phosphorylate phospholipase Cgamma1 and mitogen-activated protein kinase (MAPK). Unlike mutation of tyrosine 1212 to phenylalanine, replacement of tyrosine 1212 with glutamic acid preserved the ligand-dependent activation of VEGFR-2 and activation of VEGFR-2-associated signaling proteins including Src, phospholipase Cgamma1, and MAPK. Further analysis showed that Src activation is not required for activation of VEGFR-2, since cells co-expressing wild type receptor with kinase dead Src or wild type Src displayed no apparent effect in the ligand-dependent autophosphorylation of VEGFR-2. Similarly, expression of wild type VEGFR-2 in fibroblast (SYF) cells obtained from the triple knockout Src family kinases showed normal ligand-dependent autophosphorylation. Collectively, these results suggest that phosphorylation of tyrosine 1212 of VEGFR-2 plays a crucial role in the activation of VEGFR-2 and subsequently VEGFR-2-mediated angiogenesis.
authors.affiliation: Department of Ophthalmology, School of Medicine, Boston University, 715 Albany Street, Boston, MA 02118, USA.
authors.forename: Rosana D
authors.initials: RD
authors.lastname: Meyer
authors.forename: Volkan
authors.initials: V
authors.lastname: Dayanir
authors.forename: Fredric
authors.initials: F
authors.lastname: Majnoun
authors.forename: Nader
authors.initials: N
authors.lastname: Rahimi
mesh_terms: D000818:Animals; D015153:Blotting, Western; D018076:DNA, Complementary / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology; D004789:Enzyme Activation; D018698:Glutamic Acid / Q000737:chemistry; D007527:Isoenzymes / Q000378:metabolism; D008024:Ligands; D020935:MAP Kinase Signaling System; D051379:Mice; D016297:Mutagenesis, Site-Directed; D010649:Phenylalanine / Q000737:chemistry / Q000378:metabolism; D051966:Phospholipase C gamma; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D020794:Receptor Protein-Tyrosine Kinases / Q000737:chemistry* / Q000378:metabolism; D017978:Receptors, Growth Factor / Q000737:chemistry* / Q000378:metabolism; D040262:Receptors, Vascular Endothelial Growth Factor; D013552:Swine; D013997:Time Factors; D010738:Type C Phospholipases / Q000378:metabolism; D014443:Tyrosine / Q000737:chemistry* / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D007527:Isoenzymes; D008024:Ligands; D017978:Receptors, Growth Factor; D018698:Glutamic Acid; D014443:Tyrosine; D010649:Phenylalanine; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor; D019061:src-Family Kinases; D010738:Type C Phospholipases; D051966:Phospholipase C gamma