1. Cell Biology
  2. Neuroscience
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The endoplasmic reticulum, not the pH gradient, drives calcium refilling of lysosomes

  1. Abigail G Garrity
  2. Wuyang Wang
  3. Crystal MD Collier
  4. Sara A Levey
  5. Qiong Gao
  6. Haoxing Xu  Is a corresponding author
  1. University of Michigan, United States
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Cite this article as: eLife 2016;5:e15887 doi: 10.7554/eLife.15887

Abstract

Impaired homeostasis of lysosomal Ca2+ causes lysosome dysfunction and lysosomal storage diseases (LSDs), but the mechanisms by which lysosomes acquire and refill Ca2+ are not known. We developed a physiological assay to monitor lysosomal Ca2+ store refilling using specific activators of lysosomal Ca2+ channels to repeatedly induce lysosomal Ca2+ release. In contrast to the prevailing view that lysosomal acidification drives Ca2+ into the lysosome, inhibiting the V-ATPase H+ pump did not prevent Ca2+ refilling. Instead, pharmacological depletion or chelation of Endoplasmic Reticulum (ER) Ca2+ prevented lysosomal Ca2+ stores from refilling. More specifically, antagonists of ER IP3 receptors (IP3Rs) rapidly and completely blocked Ca2+ refilling to lysosomes, but not in cells lacking IP3Rs. Furthermore, reducing ER Ca2+ or blocking IP3Rs caused a dramatic LSD-like lysosome storage phenotype. By closely apposing each other, the ER may serve as a direct and primary source of Ca2+ to the lysosome.

Article and author information

Author details

  1. Abigail G Garrity

    Neuroscience Program, University of Michigan, Ann Arbor, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Wuyang Wang

    Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Crystal MD Collier

    Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Sara A Levey

    Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, United States
    Competing interests
    The authors declare that no competing interests exist.
  5. Qiong Gao

    Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, United States
    Competing interests
    The authors declare that no competing interests exist.
  6. Haoxing Xu

    Neuroscience Program, University of Michigan, Ann Arbor, United States
    For correspondence
    haoxingx@umich.edu
    Competing interests
    The authors declare that no competing interests exist.

Reviewing Editor

  1. David E Clapham, Howard Hughes Medical Institute, Boston Children's Hospital, United States

Publication history

  1. Received: March 9, 2016
  2. Accepted: May 20, 2016
  3. Accepted Manuscript published: May 23, 2016 (version 1)
  4. Version of Record published: June 15, 2016 (version 2)

Copyright

© 2016, Garrity 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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