1. Cell Biology
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The Sec61 translocon limits IRE1α signaling during the unfolded protein response

  1. Arunkumar Sundaram
  2. Rachel Plumb
  3. Suhila Appathurai
  4. Malaiyalam Mariappan  Is a corresponding author
  1. Yale School of Medicine, United States
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  • Cited 23
  • Views 2,665
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Cite this article as: eLife 2017;6:e27187 doi: 10.7554/eLife.27187

Abstract

IRE1α is an endoplasmic reticulum (ER) localized endonuclease activated by misfolded proteins in the ER. Previously, we demonstrated that IRE1α forms a complex with the Sec61 translocon, to which its substrate XBP1u mRNA is recruited for cleavage during ER stress (Plumb et al., 2015). Here, we probe IRE1α complexes in cells with blue native PAGE immunoblotting. We find that IRE1α forms a hetero-oligomeric complex with the Sec61 translocon that is activated upon ER stress with little change in the complex. In addition, IRE1α oligomerization, activation, and inactivation during ER stress are regulated by Sec61. Loss of the IRE1α-Sec61 translocon interaction as well as severe ER stress conditions causes IRE1α to form higher-order oligomers that exhibit continuous activation and extended cleavage of XBP1u mRNA. Thus, we propose that the Sec61-IRE1α complex defines the extent of IRE1α activity and may determine cell fate decisions during ER stress conditions.

Article and author information

Author details

  1. Arunkumar Sundaram

    Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, West Haven, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Rachel Plumb

    Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, West Haven, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Suhila Appathurai

    Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, West Haven, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Malaiyalam Mariappan

    Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, West Haven, United States
    For correspondence
    malaiyalam.mariappan@yale.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-2966-1182

Funding

National Institutes of Health (NIH 1R01GM117386-01)

  • Rachel Plumb
  • Suhila Appathurai
  • Malaiyalam Mariappan

Yale School of Medicine (Start-up)

  • Arunkumar Sundaram
  • Rachel Plumb
  • Suhila Appathurai
  • Malaiyalam Mariappan

Yale School of Medicine (Rudolph J Anderson Fellowship)

  • Arunkumar Sundaram

National Institutes of Health (T32 GM007223)

  • Rachel Plumb

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Reid Gilmore, University of Massachusetts Medical School, United States

Publication history

  1. Received: March 27, 2017
  2. Accepted: May 13, 2017
  3. Accepted Manuscript published: May 15, 2017 (version 1)
  4. Version of Record published: May 30, 2017 (version 2)

Copyright

© 2017, Sundaram 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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