Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Subscribe

Sci. Signal., 16 April 2013
Vol. 6, Issue 271, p. ra25
[DOI: 10.1126/scisignal.2003572]

RESEARCH ARTICLES

Phosphoproteomic Analysis Implicates the mTORC2-FoxO1 Axis in VEGF Signaling and Feedback Activation of Receptor Tyrosine Kinases

Guanglei Zhuang*, Kebing Yu*, Zhaoshi Jiang, Alicia Chung, Jenny Yao, Connie Ha, Karen Toy, Robert Soriano, Benjamin Haley, Elizabeth Blackwood, Deepak Sampath, Carlos Bais, Jennie R. Lill, and Napoleone Ferrara{dagger}{ddagger}

Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA.

* These authors contributed equally to this work.

{dagger} Present address: Department of Pathology and Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA.

Abstract: The vascular endothelial growth factor (VEGF) signaling pathway plays a pivotal role in normal development and also represents a major therapeutic target for tumors and intraocular neovascular disorders. The VEGF receptor tyrosine kinases promote angiogenesis by phosphorylating downstream proteins in endothelial cells. We applied a large-scale proteomic approach to define the VEGF-regulated phosphoproteome and its temporal dynamics in human umbilical vein endothelial cells and then used siRNA (small interfering RNA) screens to investigate the function of a subset of these phosphorylated proteins in VEGF responses. The PI3K (phosphatidylinositol 3-kinase)–mTORC2 (mammalian target of rapamycin complex 2) axis emerged as central in activating VEGF-regulated phosphorylation and increasing endothelial cell viability by suppressing the activity of the transcription factor FoxO1 (forkhead box protein O1), an effect that limited cellular apoptosis and feedback activation of receptor tyrosine kinases. This FoxO1-mediated feedback loop not only reduced the effectiveness of mTOR inhibitors at decreasing protein phosphorylation and cell survival but also rendered cells more susceptible to PI3K inhibition. Collectively, our study provides a global and dynamic view of VEGF-regulated phosphorylation events and implicates the mTORC2-FoxO1 axis in VEGF receptor signaling and reprogramming of receptor tyrosine kinases in human endothelial cells.

{ddagger} Corresponding author. E-mail: nferrara{at}ucsd.edu

Citation: G. Zhuang, K. Yu, Z. Jiang, A. Chung, J. Yao, C. Ha, K. Toy, R. Soriano, B. Haley, E. Blackwood, D. Sampath, C. Bais, J. R. Lill, N. Ferrara, Phosphoproteomic Analysis Implicates the mTORC2-FoxO1 Axis in VEGF Signaling and Feedback Activation of Receptor Tyrosine Kinases. Sci. Signal. 6, ra25 (2013).

Read the Full Text


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Quantitative phosphoproteomics unveils temporal dynamics of thrombin signaling in human endothelial cells.
M. van den Biggelaar, J. R. Hernandez-Fernaud, B. L. van den Eshof, L. J. Neilson, A. B. Meijer, K. Mertens, and S. Zanivan (2014)
Blood 123, e22-e36
   Abstract »    Full Text »    PDF »
Science Signaling Podcast: 16 April 2013.
G. Zhuang, N. Ferrara, and A. M. VanHook (2013)
Science Signaling 6, pc10
   Abstract »    Full Text »

To Advertise     Find Products


Science Signaling. ISSN 1937-9145 (online), 1945-0877 (print). Pre-2008: Science's STKE. ISSN 1525-8882