SNM1A acts downstream of ATM to promote the G1 cell cycle checkpoint

Biochem Biophys Res Commun. 2008 Dec 5;377(1):236-41. doi: 10.1016/j.bbrc.2008.09.130. Epub 2008 Oct 9.


We have shown previously that SNM1A colocalizes with 53BP1 at sites of double-strand breaks (DSBs) induced by IR, and that these proteins interact with or without DNA damage. However, the role of SNM1A in the DNA damage response has not been elucidated. Here, we show that SNM1A is required for an efficient G1 checkpoint arrest after IR exposure. Interestingly, the localization of SNM1A to sites of DSBs does not require either 53BP1 or H2AX, nor does the localization of 53BP1 require SNM1A. However, the localization of SNM1A does require ATM. Furthermore, SNM1A is shown to be a phosphorylation substrate of ATM in vitro, and to interact with ATM in vivo particularly after exposure of cells to IR. In addition, in the absence of SNM1A the activation of the downstream ATM target p53 is reduced. These findings suggest that SNM1A acts with ATM to promote the G1 cell cycle checkpoint.

Publication types

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

MeSH terms

  • Ataxia Telangiectasia Mutated Proteins
  • Cell Cycle Proteins / metabolism*
  • DNA Breaks, Double-Stranded
  • DNA Repair Enzymes / genetics
  • DNA Repair Enzymes / metabolism*
  • DNA-Binding Proteins / metabolism*
  • Exodeoxyribonucleases
  • G1 Phase* / radiation effects
  • Histones / metabolism
  • Humans
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Phosphorylation
  • Protein Serine-Threonine Kinases / metabolism*
  • Radiation, Ionizing
  • Tumor Suppressor Proteins / metabolism*
  • Tumor Suppressor p53-Binding Protein 1


  • Cell Cycle Proteins
  • DNA-Binding Proteins
  • H2AX protein, human
  • Histones
  • Intracellular Signaling Peptides and Proteins
  • Nuclear Proteins
  • TP53BP1 protein, human
  • Tumor Suppressor Proteins
  • Tumor Suppressor p53-Binding Protein 1
  • ATM protein, human
  • Ataxia Telangiectasia Mutated Proteins
  • Protein Serine-Threonine Kinases
  • DCLRE1B protein, human
  • Exodeoxyribonucleases
  • DNA Repair Enzymes