1. Cell Biology
  2. Developmental Biology
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Duox generated reactive oxygen species activate ATR/Chk1 to induce G2 arrest in Drosophila tracheoblasts

  1. Amrutha Kizhedathu
  2. Piyush Chhajed
  3. Lahari Yeramala
  4. Deblina Sain Basu
  5. Tina Mukherjee
  6. Vinothkumar R Kutti
  7. Arjun Guha  Is a corresponding author
  1. Institute for Stem Cell Biology and Regenerative Medicine (inStem), India
  2. National Centre for Biological Sciences, Iceland
  3. National Centre for Biological Sciences, India
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Cite this article as: eLife 2021;10:e68636 doi: 10.7554/eLife.68636

Abstract

Progenitors of the thoracic tracheal system of adult Drosophila (tracheoblasts) arrest in G2 during larval life and rekindle a mitotic program subsequently. G2 arrest is dependent on ATR-dependent phosphorylation of Chk1 that is actuated in the absence of detectable DNA damage. We are interested in the mechanisms that activate ATR/Chk1 (Kizhedathu et al., 2018, 2020). Here we report that levels of reactive oxygen species (ROS) are high in arrested tracheoblasts and decrease upon mitotic re-entry. High ROS is dependent on expression of Duox, an H2O2 generating-Dual Oxidase. ROS quenching by overexpression of Superoxide Dismutase 1, or by knockdown of Duox, abolishes Chk1 phosphorylation and results in precocious proliferation. Tracheae deficient in Duox, or deficient in both Duox and regulators of DNA damage-dependent ATR/Chk1 activation (ATRIP/TOPBP1/ Claspin), can induce phosphorylation of Chk1 in response to micromolar concentrations of H2O2 in minutes. The findings presented reveal that H2O2 activates ATR/Chk1 in tracheoblasts by a non-canonical, potentially direct, mechanism.

Data availability

All data generated or analysed during this study are included in the manuscript and supporting file; Source Data files have been provided for Figures 1,2,3,4

Article and author information

Author details

  1. Amrutha Kizhedathu

    Institute for Stem Cell Biology and Regenerative Medicine (inStem), Bangalore, India
    Competing interests
    The authors declare that no competing interests exist.
  2. Piyush Chhajed

    Institute for Stem Cell Biology and Regenerative Medicine (inStem), Bangalore, India
    Competing interests
    The authors declare that no competing interests exist.
  3. Lahari Yeramala

    National Centre for Biological Sciences, Bangalore, Iceland
    Competing interests
    The authors declare that no competing interests exist.
  4. Deblina Sain Basu

    Institute for Stem Cell Biology and Regenerative Medicine (inStem), Bangalore, India
    Competing interests
    The authors declare that no competing interests exist.
  5. Tina Mukherjee

    Institute for Stem Cell Biology and Regenerative Medicine (inStem), Bangalore, India
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-3776-5536
  6. Vinothkumar R Kutti

    Biochemistry, Biophysics and Bioinformatics, National Centre for Biological Sciences, Bangalore, India
    Competing interests
    The authors declare that no competing interests exist.
  7. Arjun Guha

    Institute for Stem Cell Biology and Regenerative Medicine (inStem), Bangalore, India
    For correspondence
    arjung@instem.res.in
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-3753-1484

Funding

Department of Biotechnology, Ministry of Science and Technology, India (inStem Core Funds)

  • Arjun Guha

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

Reviewing Editor

  1. Amin S. Ghabrial, Columbia University, United States

Publication history

  1. Received: March 24, 2021
  2. Preprint posted: March 25, 2021 (view preprint)
  3. Accepted: October 7, 2021
  4. Accepted Manuscript published: October 8, 2021 (version 1)
  5. Accepted Manuscript updated: October 11, 2021 (version 2)
  6. Version of Record published: November 16, 2021 (version 3)

Copyright

© 2021, Kizhedathu 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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Further reading

    1. Developmental Biology
    Amrutha Kizhedathu et al.
    Research Article Updated

    Imaginal progenitors in Drosophila are known to arrest in G2 during larval stages and proliferate thereafter. Here we investigate the mechanism and implications of G2 arrest in progenitors of the adult thoracic tracheal epithelium (tracheoblasts). We report that tracheoblasts pause in G2 for ~48–56 h and grow in size over this period. Surprisingly, tracheoblasts arrested in G2 express drivers of G2-M like Cdc25/String (Stg). We find that mechanisms that prevent G2-M are also in place in this interval. Tracheoblasts activate Checkpoint Kinase 1/Grapes (Chk1/Grp) in an ATR/mei-41-dependent manner. Loss of ATR/Chk1 led to precocious mitotic entry ~24–32 h earlier. These divisions were apparently normal as there was no evidence of increased DNA damage or cell death. However, induction of precocious mitoses impaired growth of tracheoblasts and the tracheae they comprise. We propose that ATR/Chk1 negatively regulate G2-M in developing tracheoblasts and that G2 arrest facilitates cellular and hypertrophic organ growth.

    1. Cell Biology
    Maria Podinovskaia et al.
    Research Article

    Cell-cell communication is an essential process in life, with endosomes acting as key organelles for regulating uptake and secretion of signaling molecules. Endocytosed material is accepted by the sorting endosome where it either is sorted for recycling or remains in the endosome as it matures to be degraded in the lysosome. Investigation of the endosome maturation process has been hampered by the small size and rapid movement of endosomes in most cellular systems. Here, we report an easy versatile live-cell imaging assay to monitor endosome maturation kinetics, which can be applied to a variety of mammalian cell types. Acute ionophore treatment led to enlarged early endosomal compartments that matured into late endosomes and fused with lysosomes to form endolysosomes. Rab5-to-Rab7 conversion and PI(3)P formation and turn over were recapitulated with this assay and could be observed with a standard widefield microscope. We used this approach to show that Snx1 and Rab11-positive recycling endosome recruitment occurred throughout endosome maturation and was uncoupled from Rab conversion. In contrast, efficient endosomal acidification was dependent on Rab conversion. The assay provides a powerful tool to further unravel various aspects of endosome maturation.