ATM phosphorylates p95/nbs1 in an S-phase checkpoint pathway

Nature. 2000 Apr 6;404(6778):613-7. doi: 10.1038/35007091.

Abstract

The rare diseases ataxia-telangiectasia (AT), caused by mutations in the ATM gene, and Nijmegen breakage syndrome (NBS), with mutations in the p95/nbs1 gene, share a variety of phenotypic abnormalities such as chromosomal instability, radiation sensitivity and defects in cell-cycle checkpoints in response to ionizing radiation. The ATM gene encodes a protein kinase that is activated by ionizing radiation or radiomimetic drugs, whereas p95/nbs1 is part of a protein complex that is involved in responses to DNA double-strand breaks. Here, because of the similarities between AT and NBS, we evaluated the functional interactions between ATM and p95/nbs1. Activation of the ATM kinase by ionizing radiation and induction of ATM-dependent responses in NBS cells indicated that p95/nbs1 may not be required for signalling to ATM after ionizing radiation. However, p95/nbs1 was phosphorylated on serine 343 in an ATM-dependent manner in vitro and in vivo after ionizing radiation. A p95/nbs1 construct mutated at the ATM phosphorylation site abrogated an S-phase checkpoint induced by ionizing radiation in normal cells and failed to compensate for this functional deficiency in NBS cells. These observations link ATM and p95/nbs1 in a common signalling pathway and provide an explanation for phenotypic similarities in these two diseases.

Publication types

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

MeSH terms

  • Ataxia Telangiectasia Mutated Proteins
  • Ataxia Telangiectasia*
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Cell Line
  • DNA / biosynthesis
  • DNA / radiation effects
  • DNA-Binding Proteins
  • Enzyme Activation / radiation effects
  • Humans
  • Mutagenesis
  • Nuclear Proteins*
  • Phosphatidylinositol 3-Kinases / genetics
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphatidylinositol 3-Kinases / radiation effects
  • Phosphorylation
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • Protein-Serine-Threonine Kinases / radiation effects
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • S Phase*
  • Serine / metabolism
  • Signal Transduction
  • Transfection
  • Tumor Suppressor Protein p53 / metabolism
  • Tumor Suppressor Proteins

Substances

  • Cell Cycle Proteins
  • DNA-Binding Proteins
  • NBN protein, human
  • Nuclear Proteins
  • Recombinant Fusion Proteins
  • Tumor Suppressor Protein p53
  • Tumor Suppressor Proteins
  • Serine
  • DNA
  • Phosphatidylinositol 3-Kinases
  • ATM protein, human
  • Ataxia Telangiectasia Mutated Proteins
  • Protein-Serine-Threonine Kinases