Abstract

Vascular endothelial growth factor (VEGF) induces angiogenesis and regulates endothelial function via production and release of nitric oxide (NO), an important signaling molecule. The molecular basis leading to NO production involves phosphatidylinositiol-3 kinase (PI3K), Akt, and endothelial nitric-oxide synthase (eNOS) activation. In this study, we have examined whether small GTP-binding proteins of the ADP-ribosylation factor (ARF) family act as molecular switches to regulate signaling cascades activated by VEGF in endothelial cells. Our results show that this growth factor can promote the rapid and transient activation of ARF1. In endothelial cells, this GTPase is present on dynamic plasma membrane ruffles. Inhibition of ARF1 expression, using RNA interference, markedly impaired VEGF-dependent eNOS phosphorylation and NO production by preventing the activation of the PI3K/Akt signaling axis. Furthermore, our data indicate that phosphorylation of Tyr(801), on VEGF receptor 2, is essential for activating Src- and ARF1-dependent signaling events leading to NO release from endothelial cells. Lastly, this mediator is known to regulate a broad variety of endothelial cell functions. Depletion of ARF1 markedly inhibits VEGF-dependent increase of vascular permeability as well as capillary tubule formation, a process important for angiogenesis. Taken together, our data indicate that ARF1 is a novel modulator of VEGF-stimulated NO release and signaling in endothelial cells.

Highlights

  • (CIHR) Grant MOP-79470 and a Heart and Stoke Foundation of Canada grant

  • BAEC were harvested at different times postVEGF treatment and analyzed for endogenous ARF1-GTP levels using the GST-GGA3 pulldown assay

  • To explore the functional significance of ARF1 activation following Vascular endothelial growth factor (VEGF) treatment, we examined signaling to the phosphatidylinositol 3 kinase (PI3K) and MAPK pathways

Read more

Summary

Introduction

(CIHR) Grant MOP-79470 and a Heart and Stoke Foundation of Canada grant We have shown previously that in endothelial cells, Tyr801 present on VEGFR-2, is highly phosphorylated in response to VEGF and is essential for Akt and eNOS activation as well as nitric oxide (NO) release [5].

Results
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call