Formation of dynamic gamma-H2AX domains along broken DNA strands is distinctly regulated by ATM and MDC1 and dependent upon H2AX densities in chromatin

Mol Cell. 2009 May 15;34(3):298-310. doi: 10.1016/j.molcel.2009.04.012.


A hallmark of the cellular response to DNA double-strand breaks (DSBs) is histone H2AX phosphorylation in chromatin to generate gamma-H2AX. Here, we demonstrate that gamma-H2AX densities increase transiently along DNA strands as they are broken and repaired in G1 phase cells. The region across which gamma-H2AX forms does not spread as DSBs persist; rather, gamma-H2AX densities equilibrate at distinct levels within a fixed distance from DNA ends. Although both ATM and DNA-PKcs generate gamma-H2AX, only ATM promotes gamma-H2AX formation to maximal distance and maintains gamma-H2AX densities. MDC1 is essential for gamma-H2AX formation at high densities near DSBs, but not for generation of gamma-H2AX over distal sequences. Reduced H2AX levels in chromatin impair the density, but not the distance, of gamma-H2AX formed. Our data suggest that H2AX fuels a gamma-H2AX self-reinforcing mechanism that retains MDC1 and activated ATM in chromatin near DSBs and promotes continued local phosphorylation of H2AX.

Publication types

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

MeSH terms

  • Adaptor Proteins, Signal Transducing
  • Animals
  • Ataxia Telangiectasia Mutated Proteins
  • B-Lymphocytes / cytology
  • B-Lymphocytes / physiology
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Chromatin / metabolism*
  • DNA / metabolism*
  • DNA Damage*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Endonucleases
  • G1 Phase / physiology
  • Genes, T-Cell Receptor alpha / genetics
  • Histones / genetics
  • Histones / metabolism*
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Mice
  • Mice, Knockout
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • Recombination, Genetic
  • Thymus Gland / cytology
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism
  • Tumor Suppressor Proteins / genetics
  • Tumor Suppressor Proteins / metabolism*


  • Adaptor Proteins, Signal Transducing
  • Cell Cycle Proteins
  • Chromatin
  • DNA-Binding Proteins
  • H2AX protein, mouse
  • Histones
  • Intracellular Signaling Peptides and Proteins
  • MDC1 protein, mouse
  • Nuclear Proteins
  • Tumor Suppressor Protein p53
  • Tumor Suppressor Proteins
  • DNA
  • Ataxia Telangiectasia Mutated Proteins
  • Atm protein, mouse
  • Protein-Serine-Threonine Kinases
  • Endonucleases
  • Dclre1c protein, mouse