Neuropilin-1 Is Expressed by Endothelial and Tumor Cells as an Isoform-Specific Receptor for Vascular Endothelial Growth Factor

Vascular endothelial growth factor (VEGF), a major regulator of angiogenesis, binds to two receptor tyrosine kinases, KDR/Flk-1 and Flt-1. We now describe the purification and the expression cloning from tumor cells of a third VEGF receptor, one that binds VEGF 165 but not VEGF 121. This isoform-specific VEGF receptor (VEGF 165R) is identical to human neuropilin-1, a receptor for the collapsin/semaphorin family that mediates neuronal cell guidance. When coexpressed in cells with KDR, neuropilin-1 enhances the binding of VEGF 165 to KDR and VEGF 165-mediated chemotaxis. Conversely, inhibition of VEGF 165 binding to neuropilin-1 inhibits its binding to KDR and its mitogenic activity for endothelial cells. We propose that neuropilin-1 is a novel VEGF receptor that modulates VEGF binding to KDR and subsequent bioactivity and therefore may regulate VEGF-induced angiogenesis.