The mechanism of MICU-dependent gating of the mitochondrial Ca2+ uniporter

  1. Vivek Garg  Is a corresponding author
  2. Junji Suzuki
  3. Ishan Paranjpe
  4. Tiffany Unsulangi
  5. Liron Boyman
  6. Lorin S Milescu
  7. W Jonathan Lederer
  8. Yuriy Kirichok  Is a corresponding author
  1. University of Maryland, United States
  2. University of California San Francisco, United States
  3. University of Maryland Baltimore, United States
  4. University of Maryland School of Medicine, United States

Abstract

Ca2+ entry into mitochondria is through the mitochondrial calcium uniporter complex (MCUcx), a Ca2+-selective channel composed of five subunit types. Two MCUcx subunits (MCU and EMRE) span the inner mitochondrial membrane, while three Ca2+-regulatory subunits (MICU1, MICU2 and MICU3) reside in the intermembrane space. Here we provide rigorous analysis of Ca2+ and Na+ fluxes via MCUcx in intact isolated mitochondria to understand the function of MICU subunits. We also perform direct patch clamp recordings of macroscopic and single MCUcx currents to gain further mechanistic insight. This comprehensive analysis shows that the MCUcx pore, composed of the EMRE and MCU subunits, is not occluded nor plugged by MICUs during the absence or presence of extramitochondrial Ca2+ as has been widely reported. Instead, MICUs potentiate activity of MCUcx as extramitochondrial Ca2+ is elevated. MICUs achieve this by modifying the gating properties of MCUcx allowing it to spend more time in the open state.

Data availability

Due to the size of the dataset, raw electrophysiology traces are available on request to the corresponding author. All information has been extracted from the raw electrophysiological traces and is available to download as source data files. All the codes or software used in analyzing the data and their sources are listed in the Key Resources Table.

Article and author information

Author details

  1. Vivek Garg

    Physiology, University of Maryland, Baltimore, United States
    For correspondence
    vgarg@som.umaryland.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-6940-5415
  2. Junji Suzuki

    Physiology, University of California San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Ishan Paranjpe

    Department of Physiology, University of California San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Tiffany Unsulangi

    Department of Physiology, University of California San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  5. Liron Boyman

    Physiology, University of Maryland, Baltimore, United States
    Competing interests
    The authors declare that no competing interests exist.
  6. Lorin S Milescu

    Biology, University of Maryland Baltimore, College Park, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-3177-7010
  7. W Jonathan Lederer

    University of Maryland School of Medicine, Baltimore, United States
    Competing interests
    The authors declare that no competing interests exist.
  8. Yuriy Kirichok

    Department of Physiology, University of California San Francisco, San Francisco, United States
    For correspondence
    yuriy.kirichok@ucsf.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-7155-843X

Funding

National Institutes of Health (R01GM134536)

  • Yuriy Kirichok

National Institutes of Health (R35GM136415)

  • Yuriy Kirichok

American Heart Association (17SDG33660926)

  • Vivek Garg

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

Ethics

Animal experimentation: All animal experiments were performed according to procedures approved by the UCSF Institutional Animal Care and Use Committee (approval # AN183460-02A) and adhered to NIH standards.

Reviewing Editor

  1. Richard S Lewis, Stanford University School of Medicine, United States

Publication history

  1. Preprint posted: April 5, 2020 (view preprint)
  2. Received: April 11, 2021
  3. Accepted: August 9, 2021
  4. Accepted Manuscript published: August 31, 2021 (version 1)
  5. Version of Record published: September 13, 2021 (version 2)

Copyright

© 2021, Garg 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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  1. Vivek Garg
  2. Junji Suzuki
  3. Ishan Paranjpe
  4. Tiffany Unsulangi
  5. Liron Boyman
  6. Lorin S Milescu
  7. W Jonathan Lederer
  8. Yuriy Kirichok
(2021)
The mechanism of MICU-dependent gating of the mitochondrial Ca2+ uniporter
eLife 10:e69312.
https://doi.org/10.7554/eLife.69312

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