Neuropilin-1 Modulates p53/Caspases Axis to Promote Endothelial Cell Survival

Ling Wang,Shamit K Dutta,Xiaolei Xu,Stephen C Ekker,Tatsuyoshi Kojima,Debabrata Mukhopadhyay,Roya Khosravi-Far,Neil Hotchin

doi:10.1371/journal.pone.0001161

Abstract

Vascular permeability factor/vascular endothelial growth factor (VPF/VEGF), one of the crucial pro-angiogenic factors, functions as a potent inhibitor of endothelial cell (EC) apoptosis. Previous progress has been made towards delineating the VPF/VEGF survival signaling downstream of the activation of VEGFR-2. Here, we seek to define the function of NRP-1 in VPF/VEGF-induced survival signaling in EC and to elucidate the concomitant molecular signaling events that are pivotal for our understanding of the signaling of VPF/VEGF. Utilizing two different in vitro cell culture systems and an in vivo zebrafish model, we demonstrate that NRP-1 mediates VPF/VEGF-induced EC survival independent of VEGFR-2. Furthermore, we show here a novel mechanism for NRP-1-specific control of the anti-apoptotic pathway in EC through involvement of the NRP-1-interacting protein (NIP/GIPC) in the activation of PI-3K/Akt and subsequent inactivation of p53 pathways and FoxOs, as well as activation of p21. This study, by elucidating the mechanisms that govern VPF/VEGF-induced EC survival signaling via NRP-1, contributes to a better understanding of molecular mechanisms of cardiovascular development and disease and widens the possibilities for better therapeutic targets.

Highlights

Apoptosis of the endothelial cell (EC) has been suggested to play an important role in a number of common and life-threatening vascular diseases, such as atherosclerosis, hypertension, and restenosis [1,2,3,4,5]
As VEGFR-1, VEGFR-2, and NRP-1 are all expressed on EC, it is difficult to distinguish their biological functions and signaling pathways induced in EC by VPF/VEGF individually
VPF/VEGF induced a significant decrease in apoptosis in porcine aortic endothelial cell (PAEC)/ NRP-1 relative to parental PAE cells, about five-and six-fold less than VPF/VEGF-stimulated parental PAEC or serum-starved PAEC/NRP-1 (Figure 1a)

Summary

Introduction

Apoptosis of the endothelial cell (EC) has been suggested to play an important role in a number of common and life-threatening vascular diseases, such as atherosclerosis, hypertension, and restenosis [1,2,3,4,5]. EC apoptotic death-induced loss of EC number and EC dysfunction may constitute an initial causative step in, and have a critical role in, the progress of many vascular pathological situations by compromising vascular wall permeability to cytokines, growth factors, lipids and immune cells, increasing smooth muscle cell proliferation and enhancing blood coagulation [6,7,8]. One functionally relevant vascular growth factor is vascular permeability factor/vascular endothelial growth factor (VPF/ VEGF) [12,13] that has been cited as one of the most important pro-angiogenic factors. Neuropilin-1 (NRP-1) was recently found to be one of the VPF/VEGF receptors, which is expressed in EC and functions as an isoform-specific receptor for VPF/VEGF [14,15]

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Results

Conclusion