Recruitment of ATR to sites of ionising radiation-induced DNA damage requires ATM and components of the MRN protein complex

Oncogene. 2006 Jun 29;25(28):3894-904. doi: 10.1038/sj.onc.1209426. Epub 2006 Feb 13.


ATM and ATR are two related kinases essential for signalling DNA damage. Although ATM is thought to be the principle kinase responsible for signalling ionising radiation (IR)-induced DNA damage, ATR also contributes to signalling this form of genotoxic stress. However, the molecular basis of differential ATM and ATR activation in response to IR remains unclear. Here, we report that ATR is recruited to sites of IR-induced DNA damage significantly later than activation of ATM. We show that ATR is recruited to IR-induced nuclear foci in G(1) and S phase of the cell cycle, supporting a role for ATR in detecting DNA damage outside of S phase. In addition, we report that recruitment of ATR to sites of IR-induced DNA damage is concomitant with appearance of large tracts of single-stranded DNA (ssDNA) and that this event is dependent on ATM and components of the Mre11/Rad50/Nbs1 (MRN) protein complex.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3T3 Cells
  • Animals
  • Ataxia Telangiectasia Mutated Proteins
  • Base Sequence
  • Cell Cycle Proteins / metabolism*
  • DNA Damage*
  • DNA Repair Enzymes
  • DNA, Single-Stranded / radiation effects*
  • DNA-Binding Proteins / metabolism*
  • HeLa Cells
  • Humans
  • MRE11 Homologue Protein
  • Mice
  • Protein-Serine-Threonine Kinases / metabolism*
  • RNA, Small Interfering
  • Radiation, Ionizing*
  • S Phase
  • Tumor Suppressor Proteins / metabolism*


  • Cell Cycle Proteins
  • DNA, Single-Stranded
  • DNA-Binding Proteins
  • MRE11 protein, human
  • Mre11a protein, mouse
  • RNA, Small Interfering
  • Tumor Suppressor Proteins
  • ATM protein, human
  • ATR protein, human
  • Ataxia Telangiectasia Mutated Proteins
  • Atm protein, mouse
  • Protein-Serine-Threonine Kinases
  • MRE11 Homologue Protein
  • DNA Repair Enzymes