ATR and ATM-dependent movement of BLM helicase during replication stress ensures optimal ATM activation and 53BP1 focus formation

Cell Cycle. 2004 Dec;3(12):1579-86. doi: 10.4161/cc.3.12.1286. Epub 2004 Dec 4.


The BLM helicase, a deficiency that markedly increases cancer incidence in humans, is required for optimal repair during DNA replication. We show that BLM rapidly moves from PML nuclear bodies to damaged replication forks, returning to PML bodies several hours later, owing to activities of the DNA damage response kinases ATR and ATM, respectively. Immunofluorescence and cellular fractionation demonstrate that BLM partitions to different sub-cellular compartments after replication stress. Unexpectedly, fibroblasts lacking BLM were deficient in phospho-ATM (S-1981) and 53-binding protein-1 (53BP1), and these proteins failed to form foci following replication stress. Expression of a dominant p53 mutant or helicase-deficient BLM restored replication stress-induced 53BP1 foci, but only mutant p53 restored optimal ATM activation. Thus, optimal repair of damaged replication fork lesions likely requires both ATR and ATM. BLM recruits 53BP1 to these lesions independent of its helicase activity, and optimal activation of ATM requires both p53 and BLM helicase activities.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphatases / genetics
  • Adenosine Triphosphatases / metabolism*
  • Ataxia Telangiectasia Mutated Proteins
  • Cell Cycle
  • Cell Cycle Proteins / metabolism*
  • DNA Helicases / genetics
  • DNA Helicases / metabolism*
  • DNA Replication*
  • DNA-Binding Proteins / metabolism*
  • Fibroblasts / cytology
  • Fibroblasts / metabolism
  • Humans
  • Intracellular Signaling Peptides and Proteins / deficiency
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Mutation / genetics
  • Phosphoproteins / deficiency
  • Phosphoproteins / metabolism*
  • Phosphorylation
  • Protein Binding
  • Protein Transport
  • Protein-Serine-Threonine Kinases / metabolism*
  • RecQ Helicases
  • Tumor Suppressor Proteins / metabolism*
  • Tumor Suppressor p53-Binding Protein 1


  • Cell Cycle Proteins
  • DNA-Binding Proteins
  • Intracellular Signaling Peptides and Proteins
  • Phosphoproteins
  • TP53BP1 protein, human
  • Tumor Suppressor Proteins
  • Tumor Suppressor p53-Binding Protein 1
  • ATM protein, human
  • ATR protein, human
  • Ataxia Telangiectasia Mutated Proteins
  • Protein-Serine-Threonine Kinases
  • Adenosine Triphosphatases
  • Bloom syndrome protein
  • DNA Helicases
  • RecQ Helicases