AMP-activated protein kinase fortifies epithelial tight junctions during energetic stress via its effector GIV/Girdin
- University of California, San Diego, United States
Abstract
Loss of epithelial polarity impacts organ development and function; it is also oncogenic. AMPK, a key sensor of metabolic stress stabilizes cell-cell junctions and maintains epithelial polarity; its activation by Metformin protects the epithelial barrier against stress and suppresses tumorigenesis. How AMPK protects the epithelium remains unknown. Here we identify GIV/Girdin as a novel effector of AMPK, whose phosphorylation at a single site is both necessary and sufficient for strengthening mammalian epithelial tight junctions and preserving cell polarity and barrier function in the face of energetic stress. Expression of an oncogenic mutant of GIV (cataloged in TCGA) that cannot be phosphorylated by AMPK increased anchorage-independent growth of tumor cells and helped these cells evade the tumor-suppressive action of Metformin. This work defines a fundamental homeostatic mechanism by which the AMPK-GIV axis reinforces cell junctions against stress-induced collapse, and also provides mechanistic insight into the tumor-suppressive action of Metformin.
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Author details
Funding
National Cancer Institute (R01CA100768)
- Marilyn G Farquhar
- Pradipta Ghosh
National Cancer Institute (R01CA160911)
- Pradipta Ghosh
National Institute of Diabetes and Digestive and Kidney Diseases (R01DK099226)
- Pradipta Ghosh
American Cancer Society (ACS-IRG 70-002)
- Pradipta Ghosh
National Cancer Institute (Postdoctoral FellowshipT32CA121938)
- Cristina C Rohena
National Institute of General Medical Sciences (R01GM071872)
- Irina Kufareva
National Institute of Allergy and Infectious Diseases (R01AI118985)
- Irina Kufareva
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2016, Aznar et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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AMP-activated protein kinase fortifies epithelial tight junctions during energetic stress via its effector GIV/Girdin
eLife 5:e20795.
https://doi.org/10.7554/eLife.20795
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