Tyrosine phosphorylation of the vascular endothelial-growth-factor receptor-2 (VEGFR-2) is modulated by Rho proteins.
The effects of Rho-specific modifying toxins on the tyrosine phosphorylation of endothelial cell proteins were investigated. Incubation of the cells with the Rho-activating toxin cytotoxic necrotizing factor 1 (CNF1) induced a marked increase in the tyrosine phosphorylation of a number of signalling intermediates of the vascular endothelial growth factor (VEGF)-mediated cascade, including focal adhesion kinase, paxillin, phospholipase Cgamma1 and a Shc-associated protein of 195 kDa. Both CNF1- and VEGF-dependent tyrosine phosphorylation of these proteins were significantly reduced by prior incubation with C3 transferase, a known inhibitor of RhoA function, suggesting a Rho-dependent mechanism. The stimulation of endothelial cells with CNF1 resulted in a marked increase in the tyrosine phosphorylation of the VEGF receptor (VEGFR)-2, which was correlated with a stimulation of its kinase activity and with its association with downstream tyrosine phosphorylated proteins. The stimulatory effect of CNF1 was specific for VEGFR-2 since the phosphotyrosine content of VEGFR-1 was not affected by the toxin. Transient overexpression of a dominant-active RhoA mutant also induced an increase in the tyrosine phosphorylation of the VEGFR-2, whereas overexpression of a dominant-inactive form of the protein was without effect. Taken together, these results indicate that Rho proteins may play an important role in angiogenesis by modulating the tyrosine phosphorylation levels of VEGFR-2.
Gingras
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Laboratoire de Médecine Moléculaire Hôpital Sainte-Justine-UQAM, C.P. 8888, Succ. Centre-ville, Montréal, Québec, Canada H3C 3P8.
Lamy
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Béliveau
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D036002:ADP Ribose Transferases / Q000378:metabolism; D000818:Animals; D001011:Aorta; D001427:Bacterial Toxins / Q000494:pharmacology; D001905:Botulinum Toxins; D002417:Cattle; D002478:Cells, Cultured; D003603:Cytotoxins / Q000494:pharmacology; D016228:Endothelial Growth Factors / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D004789:Enzyme Activation; D029968:Escherichia coli Proteins; D008222:Lymphokines / Q000494:pharmacology*; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D017978:Receptors, Growth Factor / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D040262:Receptors, Vascular Endothelial Growth Factor; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D020741:rho GTP-Binding Proteins / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
D001427:Bacterial Toxins; D003603:Cytotoxins; D016228:Endothelial Growth Factors; D029968:Escherichia coli Proteins; D008222:Lymphokines; D017978:Receptors, Growth Factor; D011994:Recombinant Proteins; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; C060296:cytotoxic necrotizing factor type 1; D019000:Phosphotyrosine; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor; D001905:Botulinum Toxins; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein