Anti-chemorepulsive Effects of Vascular Endothelial Growth Factor and Placental Growth Factor-2 in Dorsal Root Ganglion Neurons Are Mediated via Neuropilin-1 and Cyclooxygenase-derived Prostanoid Production

Abstract

Vascular endothelial growth factor (VEGF) displays neurotrophic and neuroprotective activities, but the mechanisms underlying these effects have not been defined. Neuropilin-1 (NP-1) is a receptor for VEGF 165 and placental growth factor-2 (PlGF-2), but the role of NP-1 in VEGF-dependent neurotrophic actions is unclear. Dorsal root ganglion (DRG) neurons expressed high levels of NP-1 mRNA and protein, much lower levels of KDR, and no detectable Flt-1. VEGF 165 and PlGF-2 promoted DRG growth cone formation with an effect similar to that of nerve growth factor, whereas the Flt-1-specific ligand, PlGF-1, and the KDR/Flt-4 ligand, VEGF-D, had no effect. The chemorepellent NP-1 ligand, semaphorin 3A, antagonized the response to VEGF and PlGF-2. The specific KDR inhibitor, SU5614, did not affect the anti-chemorepellent effects of VEGF and PlGF-2, whereas a novel, specific antagonist of VEGF binding to NP-1, called EG3287, prevented inhibition of growth cone collapse. VEGF stimulated prostacyclin and prostaglandin E 2 production in DRG cultures that was blocked by inhibitors of cyclooxygenases; the anti-chemorepellent activities of VEGF and PlGF-2 were abrogated by cyclooxygenase inhibitors, and a variety of prostacyclin analogues and prostaglandins strikingly inhibited growth cone collapse. These findings support a specific role for NP-1 in mediating neurotrophic actions of VEGF family members and also identify a novel role for prostanoids in the inhibition of neuronal chemorepulsion.

ADAM metalloproteases promote a developmental switch in responsiveness to the axonal repellant Sema3A

“…Thus, our analysis excluded Nrp1 molecules that are highly abundant on the surface of axons 42 , but do not mediate Sema3A signalling 43 . Nrp1 molecules, expressed by Schwann cells and DRG-associated fibroblasts in the culture 44 , were avoided as well. To ensure highly reliable results, immunofluorescence of a large number of growth cones (B1,200-4,500) was measured for each condition.…”

Ligand-induced internalization selects use of common receptor neuropilin-1 by VEGF165 and semaphorin3A

“…48 In addition to VEGF 165 , PlGF-2 is known to inhibit Sema3A-induced growth cone collapse in dorsal root ganglion neurons. 49 PlGF-2 has the potential to link Npn-1 to VEGF receptors, and thus may down-regulate Npn-1 by the same mechanism of VEGF 165 . FGF family members can also interact with Npn-1.…”

Neuropilin-1 antagonism in human carcinoma cells inhibits migration and enhances chemosensitivity

“…A functional blocking antibody against the integrin b1-subunit was from Millipore (Livingston, UK). EG3287 (purity 490%) was synthesised by Bachem Inc. (Merseyside, UK) as described previously (Cheng et al, 2004;Jia et al, 2006). Collagen type-I, cell dissociation solution, Dulbecco's modified Eagle's medium (DMEM)/25 mM HEPES, 5-fluorouracil (5-FU), paclitaxel, and cisplatin were purchased from Sigma-Aldrich (Dorset, UK).…”

“…We previously characterised a bicyclic peptide, EG3287, based on the C-terminal NRP1-binding domain of VEGF, which specifically blocked VEGF binding to NRP1 and inhibited the anti-chemorepulsive effect of VEGF in dorsal root ganglion neuronal explants (Cheng et al, 2004) and the biological effects of VEGF in vascular endothelial cells (Jia et al, 2006). In the present study, we investigated the effects of EG3287 on the functions of human carcinoma lung A549, kidney ACHN, and prostate DU145 cells expressing NRP1 but lacking VEGFR-2, and the mechanisms underlying these effects.…”