Differential Dynamics of ATR-Mediated Checkpoint Regulators

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Published on: June 14, 2012

Daniël O Warmerdam1, Roland Kanaar, Veronique A J Smits

  • 1Department of Cell Biology and Genetics, Cancer Genome Center, Erasmus MC, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands.

Journal of Nucleic Acids
|September 18, 2010
PubMed

Insights

The ATR-Chk1 DNA damage response pathway

Area of Science:

  • Cellular biology
  • Molecular biology
  • Genetics

Background:

  • The ATR-Chk1 pathway is crucial for responding to DNA damage and replication stress.
  • The spatio-temporal dynamics of key proteins in this pathway were largely unknown.

Purpose of the Study:

  • To investigate the dynamic behavior of ATRIP-ATR and Rad9-Rad1-Hus1 complexes and Chk1 in response to UV-induced DNA damage.
  • To elucidate the mechanisms of DNA damage sensing and signal propagation within the ATR-Chk1 pathway.

Main Methods:

  • Development of stable cell lines expressing GFP-fusion proteins for key pathway components.
  • Utilized photobleaching experiments in living cells to analyze protein dynamics on chromatin.
  • Investigated protein association kinetics and localization following UV irradiation.

Main Results:

  • ATRIP exhibited transient association with UV-damaged chromatin, contrasting with the more sustained interaction of the Rad9-Rad1-Hus1 complex.
  • ATRIP directly bound to UV-damaged sites, while Rad9 binding was cooperative and dependent on Rad17.
  • Chk1 dissociated from chromatin upon UV damage, but its mobility remained unchanged, indicating high dynamism.

Conclusions:

  • The study reveals distinct dynamic behaviors of ATRIP and Rad9-Rad1-Hus1 complexes in DNA damage sensing.
  • Rad17-dependent loading explains the cooperative binding of Rad9.
  • Chk1's high dynamism is maintained even after dissociation from chromatin during DNA damage response.

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