VEGF stimulates MAPK through a pathway that is unique for receptor tyrosine kinases.
We demonstrate that stimulation of primary cultures of endothelial cells with vascular endothelial cell growth factor (VEGF) results in a rapid increase in labeled guanine nucleotide bound to p21ras. Surprisingly, although VEGF stimulates ras activity, adenoviral-mediated gene transfer of a dominant negative form of ras (N17ras) had no effect on VEGF-stimulated mitogen-activated protein kinase (MAPK) activity. In contrast, treatment of endothelial cells with two structurally unrelated inhibitors of protein kinase C (PKC) abrogated VEGF-stimulated MAPK activity. In addition, inhibition of ras-Raf interactions by expression of a truncated form of Raf containing only the ras binding domain blocked VEGF-stimulated MAPK activation. These results suggest that VEGF stimulation of MAPK in endothelial cells differs from the pathway used by other members of the receptor tyrosine kinase family. In contrast, analogous to certain G-coupled receptors, VEGF appears to activate MAPK through a PKC-dependent pathway that requires a stable ras-Raf interaction but is not inhibited by N17ras expression.
Cardiology Branch, National Heart, Lung, and Blood Institute, Bethesda, Maryland 20892, USA.
A M
AM
Doanes
D D
DD
Hegland
R
R
Sethi
I
I
Kovesdi
J T
JT
Bruder
T
T
Finkel
D000260:Adenoviruses, Human / Q000502:physiology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002478:Cells, Cultured; D016228:Endothelial Growth Factors / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000502:physiology; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D008222:Lymphokines / Q000502:physiology*; D008301:Maleimides / Q000494:pharmacology; D009281:Naphthalenes / Q000494:pharmacology; D011485:Protein Binding; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D020794:Receptor Protein-Tyrosine Kinases / Q000502:physiology*; D015398:Signal Transduction; D014471:Umbilical Veins; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D018631:ras Proteins / Q000378:metabolism
D016228:Endothelial Growth Factors; D007211:Indoles; D008222:Lymphokines; D008301:Maleimides; D009281:Naphthalenes; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; C061465:calphostin complex; D004815:Epidermal Growth Factor; D020794:Receptor Protein-Tyrosine Kinases; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019204:GTP-Binding Proteins; D018631:ras Proteins; C088060:bisindolylmaleimide