Mdc1 couples DNA double-strand break recognition by Nbs1 with its H2AX-dependent chromatin retention

Claudia Lukas, Fredrik Melander, Manuel Stucki, Jacob Falck, Simon Bekker-Jensen, Michal Goldberg, Yaniv Lerenthal, Stephen P. Jackson, Jiri Bartek, Jiri Lukas*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

328 Scopus citations

Abstract

Mdc1/NFBD1 controls cellular responses to DNA damage, in part via interacting with the Mre11-Rad50-Nbs1 complex that is involved in the recognition, signalling, and repair of DNA double-strand breaks (DSBs). Here, we show that in live human cells, the transient interaction of Nbs1 with DSBs and its phosphorylation by ATM are Mdc1-independent. However, ablation of Mdc1 by siRNA or mutation of the Nbs1's FHA domain required for Mdc1 binding reduced the affinity of Nbs1 for DSB-flanking chromatin and caused aberrant pan-nuclear dispersal of Nbs1. This occurred despite normal phosphorylation of H2AX, indicating that lack of Mdc1 does not impair this DSB-induced chromatin change, but rather precludes the sustained engagement of Nbs1 with these regions. Mdc1 (but not Nbs1) became partially immobilized to chromatin after DSB generation, and siRNA-mediated depletion of H2AX prevented such relocalization of Mdc1 and uncoupled Nbs1 from DSB-flanking chromatin. Our data suggest that Mdc1 functions as an H2AX-dependent interaction platform enabling a switch from transient, Mdc1-independent recruitment of Nbs1 to DSBs towards sustained, Mdc1-dependent interactions with the surrounding chromosomal microenvironment.

Original languageAmerican English
Pages (from-to)2674-2683
Number of pages10
JournalEMBO Journal
Volume23
Issue number13
DOIs
StatePublished - 7 Jul 2004

Keywords

  • Cell cycle checkpoints
  • DNA damage
  • Live-cell imaging
  • Mdc1
  • Nbs1

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