Signal transduction by VEGF receptor-1 wild type and mutant proteins

The role of the vascular endothelial growth factor receptor-1 (VEGFR-1) in endothelial cell function is unclear. We have previously identified four ty rosine phosphorylation sites in the C-terminal tail of this receptor. We no w show that the wild type VEGFR-1 expressed in porcine aortic endothelial ( PAE/VEGFR-1) cells was able to transduce signals for increased DNA synthesi s and proliferation. Tyrosine phosphorylation of phospholipase C gamma (PLC gamma), tyrosine phosphatase SHP-2, Crk, and extracellular regulated kinas es 1 and 2 (Erk1/2) was registered in response to VEGF-A treatment of the P AE/VEGFR-1 cells. VEGFR-1 mutated at Y1213, Y1242, and Y1333 were construct ed and expressed in PAE cells, to the same level as that of PAE/VEGFR-1 cel ls. The affinities of the wild type and mutated receptors for VEGF-A(165) b inding were similar. The mutated VEGFR-1 Y1213F expressed in PAE cells was kinase inactive. PAE cells expressing the mutated VEGFR-1 Y1242F and Y1333F receptors mediated increased tyrosine phosphorylation of PLC gamma in resp onse to VEGF-A stimulation. However, these two mutant VEGFR-1 failed to med iate increased mitogenesis and were unable to stimulate increased tyrosine phosphorylation of SHP-2, Crk, and Erk1/2, indicating that the mutations le ad to a perturbation in VEGF-A-induced signal transduction. (C) 2001 Elsevi er Science Inc. All rights reserved.