ATM mediated phosphorylation of CHD4 contributes to genome maintenance

Signal Transduction Laboratory, Queensland Institute of Medical Research, Brisbane, Queensland 4006, Australia. .
Genome Integrity 01/2011; 2(1):1. DOI: 10.1186/2041-9414-2-1
Source: PubMed


In order to maintain cellular viability and genetic integrity cells must respond quickly following the induction of cytotoxic double strand DNA breaks (DSB). This response requires a number of processes including stabilisation of the DSB, signalling of the break and repair. It is becoming increasingly apparent that one key step in this process is chromatin remodelling.
Here we describe the chromodomain helicase DNA-binding protein (CHD4) as a target of ATM kinase. We show that ionising radiation (IR)-induced phosphorylation of CHD4 affects its intranuclear organization resulting in increased chromatin binding/retention. We also show assembly of phosphorylated CHD4 foci at sites of DNA damage, which might be required to fulfil its function in the regulation of DNA repair. Consistent with this, cells overexpressing a phospho-mutant version of CHD4 that cannot be phosphorylated by ATM fail to show enhanced chromatin retention after DSBs and display high rates of spontaneous damage.
These results provide insight into how CHD4 phosphorylation might be required to remodel chromatin around DNA breaks allowing efficient DNA repair to occur.

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    • "Activated ATM is recruited into foci at sites of DNA damage (31), where it then phosphorylates several DDR substrates, including H2AX at Ser139 or γ-H2AX (32), and the phosphorylation of these proteins by ATM is often associated with their recruitment and association at damaged DNA (9,10,32,33). Consistent with this, we found that the interaction of APLF at DNA damage sites also appears to be dependent on the phosphorylation of amino acid residue Ser116. "
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