Formation of Dynamic γ-H2AX Domains along Broken DNA Strands Is Distinctly Regulated by ATM and MDC1 and Dependent upon H2AX Densities in Chromatin

Academic Article

Abstract

  • A hallmark of the cellular response to DNA double-strand breaks (DSBs) is histone H2AX phosphorylation in chromatin to generate γ-H2AX. Here, we demonstrate that γ-H2AX densities increase transiently along DNA strands as they are broken and repaired in G1 phase cells. The region across which γ-H2AX forms does not spread as DSBs persist; rather, γ-H2AX densities equilibrate at distinct levels within a fixed distance from DNA ends. Although both ATM and DNA-PKcs generate γ-H2AX, only ATM promotes γ-H2AX formation to maximal distance and maintains γ-H2AX densities. MDC1 is essential for γ-H2AX formation at high densities near DSBs, but not for generation of γ-H2AX over distal sequences. Reduced H2AX levels in chromatin impair the density, but not the distance, of γ-H2AX formed. Our data suggest that H2AX fuels a γ-H2AX self-reinforcing mechanism that retains MDC1 and activated ATM in chromatin near DSBs and promotes continued local phosphorylation of H2AX. © 2009 Elsevier Inc. All rights reserved.
  • Authors

    Published In

  • Molecular Cell  Journal
  • Digital Object Identifier (doi)

    Author List

  • Savic V; Yin B; Maas NL; Bredemeyer AL; Carpenter AC; Helmink BA; Yang-Iott KS; Sleckman BP; Bassing CH
  • Start Page

  • 298
  • End Page

  • 310
  • Volume

  • 34
  • Issue

  • 3