Neuropilin-1 Signaling through p130^Cas Tyrosine Phosphorylation Is Essential for Growth Factor-Dependent Migration of Glioma and Endothelial Cells

Abstract

Neuropilin-1 (NRP1) is a receptor for vascular endothelial growth factor (VEGF) and plays an important role in mediating cell motility. However, the NRP1 signaling pathways important for cell motility are poorly understood. Here we report that p130^Cas tyrosine phosphorylation is stimulated by hepatocyte growth factor and platelet-derived growth factor in U87MG glioma cells and VEGF in endothelial cells and is dependent on NRP1 via its intracellular domain. In endothelial cells, NRP1 silencing reduced, but did not prevent, VEGF receptor 2 (VEGFR2) phosphorylation, while expression of a mutant form of NRP1 lacking the intracellular domain (NRP1ΔC) did not affect receptor phosphorylation in U87MG cells or human umbilical vein endothelial cells (HUVECs). In HUVECs, NRP1 was also required for VEGF-induced phosphorylation of proline-rich tyrosine kinase 2, which was necessary for p130^Cas phosphorylation. Importantly, knockdown of NRP1 or p130^Cas or expression of either NRP1ΔC or a non-tyrosine-phosphorylatable substrate domain mutant protein (p130^Cas15F) was sufficient to inhibit growth factor-mediated migration of glioma and endothelial cells. These data demonstrate for the first time the importance of the NRP1 intracellular domain in mediating a specific signaling pathway downstream of several receptor tyrosine kinases and identify a critical role for a novel NRP1-p130^Cas pathway in the regulation of chemotaxis.

ACKNOWLEDGMENTS

This work was supported by British Heart Foundation grants FS/06/019 to C.P.-M. and RG/06/003 to I.E., M.Y., G.B., and I.Z. and by funding from Ark Therapeutics Limited.

We thank David Selwood, Haiyan Jia, and Ashley Jarvis for the synthesis and characterization of EG00086.