VEGF activates protein kinase C-dependent, but Ras-independent Raf-MEK-MAP kinase pathway for DNA synthesis in primary endothelial cells

Oncogene. 1999 Apr 1;18(13):2221-30. doi: 10.1038/sj.onc.1202527.

Abstract

KDR/FIk-1 tyrosine kinase, one of the two VEGF receptors induces mitogenesis and differentiation of vascular endothelial cells. We have previously reported that a major target molecule of KDR/Flk-1 kinase is PLC-gamma, and that VEGF induces activation of MAP kinase, mainly mediated by protein kinase C (PKC) in the NIH3T3 cells overexpressing KDR/FIk-1 (Takahashi and Shibuya, 1997). However, the signal transduction initiated from VEGF in endothelial cells remains to be elucidated. In primary sinusoidal endothelial cells which showed strictly VEGF-dependent growth, we found that VEGF stimulated the activation of Raf-1-MEK-MAP kinase cascade. To our surprise, an important regulator, Ras was not efficiently activated to a significant level in response to VEGF. Consistent with this, dominant-negative Ras did not block the VEGF-induced phosphorylation of MAP kinase. On the other hand, PKC-specific inhibitors severely reduced VEGF-dependent phosphorylation of MEK, activation of MAP kinase and subsequent DNA synthesis. A potent PI3 kinase inhibitor, Wortmannin, could not inhibit either of them. These results suggest that in primary endothelial cells, VEGF-induced activation of Raf-MEK-MAP kinase and DNA synthesis are mainly mediated by PKC-dependent pathway, much more than by Ras-dependent or PI3 kinase-dependent pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3T3 Cells / drug effects
  • Adenoviridae / genetics
  • Adenoviridae / physiology
  • Androstadienes / pharmacology
  • Animals
  • Calcium-Calmodulin-Dependent Protein Kinases / physiology*
  • Carbazoles / pharmacology
  • Chromones / pharmacology
  • DNA Replication / drug effects*
  • Endothelial Growth Factors / pharmacology*
  • Endothelium, Vascular / cytology
  • Endothelium, Vascular / drug effects*
  • Endothelium, Vascular / metabolism
  • Enzyme Activation
  • Enzyme Inhibitors / pharmacology
  • Flavonoids / pharmacology
  • Genes, ras
  • Genetic Vectors / genetics
  • Genetic Vectors / physiology
  • Indoles / pharmacology
  • Lymphokines / pharmacology*
  • MAP Kinase Kinase Kinase 1*
  • Maleimides / pharmacology
  • Mice
  • Morpholines / pharmacology
  • Phosphatidylinositol 3-Kinases / physiology
  • Phosphoinositide-3 Kinase Inhibitors
  • Protein Isoforms / physiology
  • Protein Kinase C / physiology*
  • Protein Serine-Threonine Kinases / antagonists & inhibitors
  • Protein Serine-Threonine Kinases / physiology*
  • Proto-Oncogene Proteins c-raf / physiology*
  • Proto-Oncogene Proteins p21(ras) / physiology
  • Rats
  • Receptor Protein-Tyrosine Kinases / physiology
  • Receptors, Growth Factor / physiology
  • Receptors, Vascular Endothelial Growth Factor
  • Signal Transduction / drug effects*
  • Tetradecanoylphorbol Acetate / pharmacology
  • Transfection
  • Vascular Endothelial Growth Factor A
  • Vascular Endothelial Growth Factors
  • Wortmannin

Substances

  • Androstadienes
  • Carbazoles
  • Chromones
  • Endothelial Growth Factors
  • Enzyme Inhibitors
  • Flavonoids
  • Indoles
  • Lymphokines
  • Maleimides
  • Morpholines
  • Phosphoinositide-3 Kinase Inhibitors
  • Protein Isoforms
  • Receptors, Growth Factor
  • Vascular Endothelial Growth Factor A
  • Vascular Endothelial Growth Factors
  • Go 6976
  • 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
  • Receptor Protein-Tyrosine Kinases
  • Receptors, Vascular Endothelial Growth Factor
  • Protein Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-raf
  • Protein Kinase C
  • Calcium-Calmodulin-Dependent Protein Kinases
  • MAP Kinase Kinase Kinase 1
  • Map3k1 protein, mouse
  • Proto-Oncogene Proteins p21(ras)
  • bisindolylmaleimide I
  • Tetradecanoylphorbol Acetate
  • 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one
  • Wortmannin