Vascular endothelial growth factor receptor-2 and neuropilin-1 form a receptor complex that is responsible for the differential signaling potency of VEGF(165) and VEGF(121).
The two most abundant secreted isoforms of vascular endothelial growth factor A (VEGF(165) and VEGF(121)) are formed as a result of differential splicing of the VEGF-A gene. VEGF(165) and VEGF(121) share similar affinities at the isolated VEGF receptor (VEGFR)-2 but have been previously demonstrated to have differential ability to activate VEGFR-2-mediated effects on endothelial cells. Herein we investigate whether the recently described VEGF(165) isoform-specific receptor neuropilin-1 (Npn-1) is responsible for the difference in potency observed for these ligands. We demonstrate that although VEGFR-2 and Npn-1 form a complex, this complex does not result in an increase in VEGF(165) binding affinity. Therefore, the differential activity of VEGF(165) and VEGF(121) cannot be explained by a differential binding affinity for the complex. Using an antagonist that competes for VEGF(165) binding at the VEGFR-2.Npn-1 complex, we observe specific antagonism of VEGF(165)-meditated phosphorylation of VEGFR-2 without affecting the VEGF(121) response. These data indicate that the formation of the complex is responsible for the increased potency of VEGF(165) versus VEGF(121). Taken together, these data suggest a receptor-clustering role for Npn-1, as opposed to Npn-1 behaving as an affinity-converting subunit.
Whitaker
G B
GB
Department of Cardiovascular Research, Procter & Gamble Pharmaceuticals, Health Care Research Center, 8700 Mason-Montgomery Road, Mason, Ohio 45040, USA.
Limberg
B J
BJ
Rosenbaum
J S
JS
D000345:Affinity Labels; D000818:Animals; D001667:Binding, Competitive; D019556:COS Cells; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D016228:Endothelial Growth Factors / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000378:metabolism; D006801:Humans; D008222:Lymphokines / Q000378:metabolism*; D046911:Macromolecular Substances; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D039942:Neuropilin-1; D010766:Phosphorylation; D000072483:Placenta Growth Factor; D011257:Pregnancy Proteins / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D017978:Receptors, Growth Factor / Q000378:metabolism*; D040262:Receptors, Vascular Endothelial Growth Factor; D015398:Signal Transduction; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D000345:Affinity Labels; D016228:Endothelial Growth Factors; D008222:Lymphokines; D046911:Macromolecular Substances; D009419:Nerve Tissue Proteins; C000608036:PGF protein, human; D011257:Pregnancy Proteins; D017978:Receptors, Growth Factor; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D000072483:Placenta Growth Factor; D039942:Neuropilin-1; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor