Activation of ATM and Chk2 kinases in relation to the amount of DNA strand breaks

Giacomo Buscemi, Paola Perego, Nives Carenini, Makoto Nakanishi, Luciana Chessa, Junjie Chen, KumKum Khanna, Domenico Delia

Research output: Contribution to journalArticlepeer-review


The diverse checkpoint responses to DNA damage may reflect differential sensitivities by molecular components of the damage-signalling network to the type and amount of lesions. Here, we determined the kinetics of activation of the checkpoint kinases ATM and Chk2 (the latter substrate of ATM) in relation to the initial yield of genomic DNA single-strand (SSBs) and double-strand breaks (DSBs). We show that doses of γ-radiation (IR) as low as 0.25 Gy, which generate vast numbers of SSBs but only a few DSBs per cell (19 DSBs per cell (e.g. 1 Gy), which cause Chk2 autophosphorylation on Thr387, Chk2-dependent accumulation of p21waf1 and checkpoint arrest in the S phase. Our results indicate that, in contrast to ATM, Chk2 activity is triggered by a greater number of DSBs, implying that, below a certain threshold level of lesions (

Original languageEnglish
Pages (from-to)7691-7700
Number of pages10
Issue number46
Publication statusPublished - Oct 7 2004


  • ATM
  • Checkpoints
  • Chk2
  • DNA double-strand breaks

ASJC Scopus subject areas

  • Molecular Biology
  • Cancer Research
  • Genetics


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