Rapid activation of ATM on DNA flanking double-strand breaks

Nat Cell Biol. 2007 Nov;9(11):1311-8. doi: 10.1038/ncb1651. Epub 2007 Oct 21.

Abstract

The tumour-suppressor gene ATM, mutations in which cause the human genetic disease ataxia telangiectasia (A-T), encodes a key protein kinase that controls the cellular response to DNA double-strand breaks (DSBs). DNA DSBs caused by ionizing radiation or chemicals result in rapid ATM autophosphorylation, leading to checkpoint activation and phosphorylation of substrates that regulate cell-cycle progression, DNA repair, transcription and cell death. However, the precise mechanism by which damaged DNA induces ATM and checkpoint activation remains unclear. Here, we demonstrate that linear DNA fragments added to Xenopus egg extracts mimic DSBs in genomic DNA and provide a platform for ATM autophosphorylation and activation. ATM autophosphorylation and phosphorylation of its substrate NBS1 are dependent on DNA fragment length and the concentration of DNA ends. The minimal DNA length required for efficient ATM autophosphorylation is approximately 200 base pairs, with cooperative autophosphorylation induced by DNA fragments of at least 400 base pairs. Importantly, full ATM activation requires it to bind to DNA regions flanking DSB ends. These findings reveal a direct role for DNA flanking DSB ends in ATM activation.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Ataxia Telangiectasia Mutated Proteins
  • Cell Cycle Proteins / chemistry
  • Cell Cycle Proteins / drug effects
  • Cell Cycle Proteins / metabolism*
  • Cell Extracts / chemistry
  • DNA Breaks, Double-Stranded*
  • DNA* / pharmacology
  • DNA* / physiology
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / drug effects
  • DNA-Binding Proteins / metabolism*
  • Enzyme Activation / drug effects
  • Enzyme Activation / physiology
  • Enzyme Inhibitors / pharmacology
  • Humans
  • Morpholines / pharmacology
  • Ovum / chemistry
  • Protein-Serine-Threonine Kinases / chemistry
  • Protein-Serine-Threonine Kinases / drug effects
  • Protein-Serine-Threonine Kinases / metabolism*
  • Pyrones / pharmacology
  • Tumor Suppressor Proteins / chemistry
  • Tumor Suppressor Proteins / drug effects
  • Tumor Suppressor Proteins / metabolism*
  • Up-Regulation
  • Xenopus

Substances

  • 2-morpholin-4-yl-6-thianthren-1-yl-pyran-4-one
  • Cell Cycle Proteins
  • Cell Extracts
  • DNA-Binding Proteins
  • Enzyme Inhibitors
  • Morpholines
  • Pyrones
  • Tumor Suppressor Proteins
  • DNA
  • ATM protein, human
  • Ataxia Telangiectasia Mutated Proteins
  • Protein-Serine-Threonine Kinases