1. Biochemistry and Chemical Biology
  2. Cell Biology

Actin dynamics tune the integrated stress response by regulating eukaryotic initiation factor 2α dephosphorylation

  1. Joseph E Chambers
  2. Lucy E Dalton
  3. Hanna J Clarke
  4. Elke Malzer
  5. Caia S Dominicus
  6. Vruti Patel
  7. Greg Moorhead
  8. David Ron
  9. Stefan J Marciniak  Is a corresponding author
  1. University of Cambridge, United Kingdom
  2. University of Calgary, Canada
https://doi.org/10.7554/eLife.04872
Share this article
Cite this article
  1. Joseph E Chambers
  2. Lucy E Dalton
  3. Hanna J Clarke
  4. Elke Malzer
  5. Caia S Dominicus
  6. Vruti Patel
  7. Greg Moorhead
  8. David Ron
  9. Stefan J Marciniak
(2015)
Actin dynamics tune the integrated stress response by regulating eukaryotic initiation factor 2α dephosphorylation
eLife 4:e04872.
https://doi.org/10.7554/eLife.04872
  2. Download BibTeX
  3. Download .RIS

Abstract

Four stress-sensing kinases phosphorylate the alpha subunit of eukaryotic translation initiation factor 2 (eIF2α) to activate the integrated stress response (ISR). In animals, the ISR is antagonised by selective eIF2α phosphatases comprising a catalytic protein phosphatase 1 (PP1) subunit in complex with a PPP1R15-type regulatory subunit. An unbiased search for additional conserved components of the PPP1R15-PP1 phosphatase identified monomeric G-actin. Like PP1, G-actin associated with the functional core of PPP1R15 family members and G-actin depletion, by the marine toxin jasplakinolide, destabilised the endogenous PPP1R15A-PP1 complex. The abundance of the ternary PPP1R15-PP1-G-actin complex was responsive to global changes in the polymeric status of actin, as was its eIF2α-directed phosphatase activity, while localised G-actin depletion at sites enriched for PPP1R15 enhanced eIF2α phosphorylation and the downstream ISR. G-actin's role as an stabilizer of the PPP1R15-containing holophosphatase provides a mechanism for integrating signals regulating actin dynamics with stresses that trigger the ISR.

Article and author information

Author details

  1. Joseph E Chambers

    Cambridge Institute for Medical Research, Department of Medicine, University of Cambridge, Cambridge, United Kingdom
    Competing interests
    No competing interests declared.

  2. Lucy E Dalton

    Cambridge Institute for Medical Research, Department of Medicine, University of Cambridge, Cambridge, United Kingdom
    Competing interests
    No competing interests declared.

  3. Hanna J Clarke

    Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
    Competing interests
    No competing interests declared.

  4. Elke Malzer

    Cambridge Institute for Medical Research, Department of Medicine, University of Cambridge, Cambridge, United Kingdom
    Competing interests
    No competing interests declared.

  5. Caia S Dominicus

    Cambridge Institute for Medical Research, Department of Medicine, University of Cambridge, Cambridge, United Kingdom
    Competing interests
    No competing interests declared.

  6. Vruti Patel

    Cambridge Institute for Medical Research, Department of Medicine, University of Cambridge, Cambridge, United Kingdom
    Competing interests
    No competing interests declared.

  7. Greg Moorhead

    Department of Biological Sciences, University of Calgary, Calgary, Canada
    Competing interests
    No competing interests declared.

  8. David Ron

    Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
    Competing interests
    David Ron, Reviewing editor, eLife.

  9. Stefan J Marciniak

    Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
    For correspondence
    sjm20@cam.ac.uk
    Competing interests
    No competing interests declared.

Copyright

© 2015, Chambers 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.

Metrics

  • 4,159
    views
  • 1,042
    downloads
  • 83
    citations

Views, downloads and citations are aggregated across all versions of this paper published by eLife.

Citations by DOI

Download links

A two-part list of links to download the article, or parts of the article, in various formats.

Downloads (link to download the article as PDF)

Open citations (links to open the citations from this article in various online reference manager services)

Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)

  1. Joseph E Chambers
  2. Lucy E Dalton
  3. Hanna J Clarke
  4. Elke Malzer
  5. Caia S Dominicus
  6. Vruti Patel
  7. Greg Moorhead
  8. David Ron
  9. Stefan J Marciniak
(2015)
Actin dynamics tune the integrated stress response by regulating eukaryotic initiation factor 2α dephosphorylation
eLife 4:e04872.
https://doi.org/10.7554/eLife.04872

Share this article

https://doi.org/10.7554/eLife.04872

Categories and tags

Research organisms

Further reading

    1. Biochemistry and Chemical Biology
    2. Structural Biology and Molecular Biophysics

    G-actin provides substrate-specificity to eukaryotic initiation factor 2α holophosphatases

    Ruming Chen, Cláudia Rato ... David Ron
    Research Article Updated

    Dephosphorylation of eukaryotic translation initiation factor 2a (eIF2a) restores protein synthesis at the waning of stress responses and requires a PP1 catalytic subunit and a regulatory subunit, PPP1R15A/GADD34 or PPP1R15B/CReP. Surprisingly, PPP1R15-PP1 binary complexes reconstituted in vitro lacked substrate selectivity. However, selectivity was restored by crude cell lysate or purified G-actin, which joined PPP1R15-PP1 to form a stable ternary complex. In crystal structures of the non-selective PPP1R15B-PP1G complex, the functional core of PPP1R15 made multiple surface contacts with PP1G, but at a distance from the active site, whereas in the substrate-selective ternary complex, actin contributes to one face of a platform encompassing the active site. Computational docking of the N-terminal lobe of eIF2a at this platform placed phosphorylated serine 51 near the active site. Mutagenesis of predicted surface-contacting residues enfeebled dephosphorylation, suggesting that avidity for the substrate plays an important role in imparting specificity on the PPP1R15B-PP1G-actin ternary complex.