Neuropilin-1 mediates collapsin-1/semaphorin III inhibition of endothelialcell motility: Functional competition of collapsin-1 and vascular endothelial growth factor-165

Neuropilin-1 (NRP1) is a receptor for two unrelated ligands with disparate activities, vascular endothelial growth factor-165 (VEGF(165)), an angiogen esis factor, and semaphorin/collapsins, mediators of neuronal guidance. To determine whether semaphorin/collapsins could interact with NRP1 in nonneur onal cells, the effects of recombinant collapsin-1 on endothelial cells (EC ) were examined. Collapsin-1 inhibited the motility of porcine aortic EC (P AEC) expressing NRP1 alone; coexpressing KDR and NRP1 (PAEC/KDR/NRP1), but not parental PAEC; or PAEC expressing KDR alone. The motility of PAEC expre ssing NRP1 was inhibited by 65-75% and this inhibition was abrogated by ant i-NRP1 antibody. In contrast,VEGF(165) stimulated the motility of PAEC/KDR/ NRP1. When VEGF(165) and collapsin-1 were added simultaneously to PAEC/KDR/ NRP1, dorsal root ganglia (DRG), and COS-7/NRP1 cells, they competed with e ach other in EC motility, DRG collapse, and NRP1-binding assays, respective ly, suggesting that the two ligands have over-lapping-NRP1 binding sites. C ollapsin-1 rapidly disrupted the formation of lamellipodia and induced depo lymerization of F-actin in an NRP1-dependent manner. In an in vitro angioge nesis assay, collapsin-1 inhibited the capillary sprouting of EC from rat a ortic ring segments. These results suggest that collapsin-1 can inhibit EC motility as well as axon motility, that: these inhibitory effects on motili ty are mediated by NRP1, and that VEGF(165) and collapsin-1 compete for NRP 1-binding sites.