Phosphorylation of histone H2AX at M phase in human cells without DNA damage response

Biochem Biophys Res Commun. 2005 Oct 28;336(3):807-12. doi: 10.1016/j.bbrc.2005.08.164.


A variant of histone H2A, H2AX, is phosphorylated on Ser139 in response to DNA double-strand breaks (DSBs), and clusters of the phosphorylated form of H2AX (gamma-H2AX) in nuclei of DSB-induced cells show foci at breakage sites. Here, we show phosphorylation of H2AX in a cell cycle-dependent manner without any detectable DNA damage response. Western blot and immunocytochemical analyses with the anti-gamma-H2AX antibody revealed that H2AX is phosphorylated at M phase in HeLa cells. In ataxia-telangiectasia cells lacking ATM kinase activity, gamma-H2AX was scarcely detectable in the mitotic chromosomes, suggesting involvement of ATM in M-phase phosphorylation of H2AX. Single-cell gel electrophoresis assay and Western blot analysis with the anti-phospho-p53 (Ser15) antibody indicated that H2AX in human M-phase cells is phosphorylated independently of DSB and DNA damage signaling. Even in the absence of DNA damage, phosphorylation of H2AX in normal cell cycle progression may contribute to maintenance of genomic integrity.

MeSH terms

  • Ataxia Telangiectasia Mutated Proteins
  • Cell Cycle
  • Cell Cycle Proteins / metabolism
  • Cell Line, Tumor
  • Cell Proliferation
  • Chromosomes, Human / enzymology
  • DNA Damage*
  • DNA-Binding Proteins / metabolism
  • HeLa Cells
  • Histones / metabolism*
  • Humans
  • Mitosis*
  • Phosphorylation
  • Protein-Serine-Threonine Kinases / metabolism
  • Tumor Suppressor Protein p53 / metabolism
  • Tumor Suppressor Proteins / metabolism


  • Cell Cycle Proteins
  • DNA-Binding Proteins
  • H2AX protein, human
  • Histones
  • Tumor Suppressor Protein p53
  • Tumor Suppressor Proteins
  • ATM protein, human
  • Ataxia Telangiectasia Mutated Proteins
  • Protein-Serine-Threonine Kinases