Abstract
Neuropilin-1 (NRP-1) has been found to be expressed by endothelial cells and tumor cells as an isoform-specific receptor for vascular permeability factor/vascular endothelial growth factor (VEGF). Previous studies were mainly focused on the extracellular domain of NRP-1 that can bind to VEGF165 and, thus, enables NRP-1 to act as a co-receptor for VEGF165, which enhances its binding to VEGFR-2 and its bioactivity. However, the exact functional roles and related signaling mechanisms of NRP-1 in angiogenesis are not well understood. In this study we constructed a chimeric receptor, EGNP-1, by fusing the extracellular domain of epidermal growth factor receptor to the transmembrane and intracellular domains of NRP-1 and transduced it into HUVECs with a retroviral expression vector. We observed that NRP-1/EGNP-1 mediates ligand-stimulated migration of human umbilical vein endothelial cells (HUVECs) but not proliferation. Our results show that NRP-1 alone can mediate HUVEC migration through its intracellular domain, and its C-terminal three amino acids (SEA-COOH) are essential for the process. We demonstrate that phosphatidylinositol 3-kinase inhibitor Ly294002 and the p85 dominant negative mutant can block NRP-1-mediated HUVEC migration. NRP-1-mediated migration can be significantly reduced by overexpression of the dominant negative mutant of RhoA (RhoA-19N). In addition, Gq family proteins and Gbetagamma subunits are also required for NRP-1-mediated HUVEC migration. These results show for the first time that NRP-1 can independently promote cell signaling in endothelial cells and also demonstrate the importance of last three amino acids of NRP-1 for its function.
Highlights
Angiogenesis, the formation of vascular networks by endothelial cells (ECs)1 sprouting from the vascular bed, occurs in NRP-1 is a 130 –135-kDa cell surface glycoprotein
Previous studies were mainly focused on the extracellular domain of NRP-1 that can bind to VEGF165 and, enables NRP-1 to act as a co-receptor for VEGF165, which enhances its binding to VEGFR-2 and its bioactivity
To investigate the biological activities and the specific signaling events mediated by NRP-1 in ECs, we developed a chimeric receptor, EGNP-1, by fusing the extracellular domain of epidermal growth factor receptor (EGFR) to the transmembrane and intracellular domains of NRP-1 (Fig. 1a)
Summary
Angiogenesis, the formation of vascular networks by endothelial cells (ECs)1 sprouting from the vascular bed, occurs in NRP-1 is a 130 –135-kDa cell surface glycoprotein. To investigate the biological activities and the specific signaling events mediated by NRP-1 in ECs, we developed a chimeric receptor, EGNP-1, by fusing the extracellular domain of EGFR to the transmembrane and intracellular domains of NRP-1 (Fig. 1a).
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