The role of phosphatidylinositol 3-kinase in vascular endothelial growth factor signaling.
Vascular endothelial growth factor (VEGF) receptor Flk-1/KDR in endothelial cells is activated during vasculogenesis and angiogenesis upon ligand-receptor interaction. Activated Flk-1/KDR has been shown to recruit Src homology 2 domain-containing signaling molecules that are known to serve as links to the activation of the mitogen-activated protein (MAP) kinase signaling pathway. To define the functional significance of phosphatidylinositol (PI) 3-kinase in VEGF signaling, we have examined its role in human umbilical vein endothelial cell (HUVEC) cycle progression. We show herein that p85, the regulatory subunit of PI 3-kinase, is constitutively associated with Flk-1/KDR. The treatment of HUVECs with VEGF promoted tyrosine autophosphorylation of Flk-1/KDR and also induced phosphorylation of p85. This was followed by an increase in the PI 3-kinase activity, which was sensitive to wortmannin, a potent PI 3-kinase inhibitor. VEGF also induced a striking activation of MAP kinase in a time-dependent manner. Inhibition studies with both a dominant-negative p85 mutant and the PI 3-kinase inhibitor, wortmannin, were employed to show for the first time that VEGF-stimulated PI 3-kinase modulates MAP kinase activation and nuclear events such as transcription from c-fos promoter and entry into the synthesis (S)-phase. Our data demonstrate the importance of PI 3-kinase as a necessary signaling component of VEGF-mediated cell cycle progression.
Thakker
G D
GD
Department of Cardiothoracic Surgery, Weill Medical College of Cornell University, New York, New York 10021, USA.
Hajjar
D P
DP
Muller
W A
WA
Rosengart
T K
TK
D000730:Androstadienes / Q000494:pharmacology; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics; D016228:Endothelial Growth Factors / Q000502:physiology*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D008222:Lymphokines / Q000502:physiology*; D009687:Nuclear Proteins / Q000235:genetics; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D017978:Receptors, Growth Factor / Q000378:metabolism; D040262:Receptors, Vascular Endothelial Growth Factor; D026362:Serum Response Factor; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics; D015533:Transcriptional Activation; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D000077191:Wortmannin
D000730:Androstadienes; D004268:DNA-Binding Proteins; D016228:Endothelial Growth Factors; D004791:Enzyme Inhibitors; D005419:Flavonoids; D008222:Lymphokines; D009687:Nuclear Proteins; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D020794:Receptor Protein-Tyrosine Kinases; D017978:Receptors, Growth Factor; D040262:Receptors, Vascular Endothelial Growth Factor; D026362:Serum Response Factor; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D000077191:Wortmannin; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one