MDC1 is a mediator of the mammalian DNA damage checkpoint

@article{Stewart2003MDC1IA,
  title={MDC1 is a mediator of the mammalian DNA damage checkpoint},
  author={Grant S. Stewart and Bin Wang and Colin R Bignell and A. Malcolm R. Taylor and Stephen J. Elledge},
  journal={Nature},
  year={2003},
  volume={421},
  pages={961-966}
}
To counteract the continuous exposure of cells to agents that damage DNA, cells have evolved complex regulatory networks called checkpoints to sense DNA damage and coordinate DNA replication, cell-cycle arrest and DNA repair. It has recently been shown that the histone H2A variant H2AX specifically controls the recruitment of DNA repair proteins to the sites of DNA damage. Here we identify a novel BRCA1 carboxy-terminal (BRCT) and forkhead-associated (FHA) domain-containing protein, MDC1… 

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TLDR
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TLDR
It is demonstrated that GIT2 coordinates the levels of proteins in the DNA damage response (DDR), and GIT 2-knockout mice demonstrated a greater susceptibility to DNA damage than their wild-type littermates and plays an important role in MRE11/ATM/H2AX-mediated DNA damage responses.
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TLDR
A link between the cellular response to DNA damage and cell cycle regulation is revealed, suggesting that MDC1, known to have a role in checkpoint regulation, executes part of this role by binding the anaphase-promoting complex/cyclosome (APC/C), an E3 ubiquitin ligase that controls the cell cycle.
DNA Damage Regulates Chk2 Association with Chromatin*
TLDR
Using chromatin fractionation as well as immunostaining combined with detergent pre-extraction, it is found that a small pool of Chk2 is associated with chromatin prior to DNA damage, and data suggest that DNA damage induces activation of chromatin-bound Chk 2 by a Chromatin-derived signal, and that this results in dissociation of activated Chk1 from chromatin, facilitating further signal amplification and transmission to soluble substrates.
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