Duox-generated reactive oxygen species activate ATR/Chk1 to induce G2 arrest in Drosophila tracheoblasts

Elife. 2021 Oct 8;10:e68636. doi: 10.7554/eLife.68636.


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 ataxia telangiectasia mutated and rad3-related kinase (ATR)-dependent phosphorylation of checkpoint kinase 1 (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; Kizhedathu et al., 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.

Keywords: ATR; Chk1/grapes; D. melanogaster; Drosophila tracheoblasts; Duox; G2 arrest; ROS; cell biology; developmental biology.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Cycle Proteins / genetics*
  • Cell Cycle Proteins / metabolism
  • Checkpoint Kinase 1 / genetics*
  • Checkpoint Kinase 1 / metabolism
  • Drosophila Proteins / genetics*
  • Drosophila Proteins / metabolism
  • Drosophila melanogaster / physiology*
  • Dual Oxidases / genetics*
  • Dual Oxidases / metabolism
  • G2 Phase Cell Cycle Checkpoints / genetics*
  • Protein Serine-Threonine Kinases / genetics*
  • Protein Serine-Threonine Kinases / metabolism
  • Reactive Oxygen Species / metabolism*


  • Cell Cycle Proteins
  • Drosophila Proteins
  • Reactive Oxygen Species
  • Dual Oxidases
  • Checkpoint Kinase 1
  • Mei-41 protein, Drosophila
  • Protein Serine-Threonine Kinases
  • grp protein, Drosophila

Grant support

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