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Non-redundant Functions of ATM and DNA-PKcs in Response to DNA Double-Strand Breaks

Pierre Caron1, Jonathan Choudjaye1, Thomas Clouaire1

  • 1Université de Toulouse, UPS, LBCMCP, 118 route de Narbonne, 31062 Toulouse, France; CNRS, LBCMCP, 31062 Toulouse, France.

Cell Reports
|November 21, 2015
PubMed

Insights

DNA double-strand breaks trigger a DNA damage response (DDR) involving ATM and DNA-PKcs kinases. This study reveals their distinct roles in repair foci formation and chromatin organization, ensuring accurate DNA repair and cell survival.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Genetics

Background:

  • DNA double-strand breaks (DSBs) are critical DNA lesions that activate the DNA damage response (DDR).
  • The PI3K-like kinases, ataxia telangiectasia mutated (ATM) and DNA-dependent protein kinase (DNA-PKcs), are central to the DDR, but their precise, sequential roles remain debated.
  • Understanding the spatiotemporal dynamics and distinct functions of ATM and DNA-PKcs is crucial for comprehending DDR mechanisms.

Purpose of the Study:

  • To elucidate the distinct functions of ATM and DNA-PKcs in the early stages of the DNA damage response.
  • To investigate the spatial spreading and recruitment dynamics of ATM and DNA-PKcs at DSB sites.
  • To determine the roles of these kinases in higher-order chromatin organization and repair foci formation.

Main Methods:

  • Utilized the DIvA system for inducible and site-specific DSB generation.
  • Employed high-resolution mapping techniques to analyze kinase distribution around DSBs.
  • Applied advanced microscopy to visualize kinase recruitment and chromatin organization in real-time.
  • Investigated the impact of ATM and DNA-PKcs depletion on DSB repair and γH2AX domain formation.

Main Results:

  • Both ATM and DNA-PKcs spread in cis around DSBs, irrespective of the repair pathway.
  • ATM and DNA-PKcs exhibit non-overlapping functions in end joining and γH2AX domain establishment.
  • ATM is essential for the spatial clustering of multiple DSBs into distinct repair foci.
  • ATM influences not only chromatin modifications but also higher-order chromatin structure.

Conclusions:

  • ATM and DNA-PKcs play distinct, non-overlapping roles in the DDR following DSBs.
  • ATM's function extends to organizing higher-order chromatin structures, crucial for accurate DSB repair.
  • These findings clarify the mechanistic contributions of ATM and DNA-PKcs to maintaining genome integrity and cell survival.
Keywords:
ChIP-chipDSB repairPI 3-kinaseschromatinγH2AX

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