Chromodomain helicase DNA-binding protein 4 (CHD4) regulates homologous recombination DNA repair, and its deficiency sensitizes cells to poly(ADP-ribose) polymerase (PARP) inhibitor treatment.

Abstract	To ensure genome stability, cells have evolved a robust defense mechanism to detect, signal, and repair damaged DNA that is generated by exogenous stressors such as ionizing radiation, endogenous stressors such as free radicals, or normal physiological processes such as DNA replication. Homologous recombination (HR) repair is a critical pathway of repairing DNA double strand breaks, and it plays an essential role in maintaining genomic integrity. Previous studies have shown that BRIT1, also known as MCPH1, is a key regulator of HR repair. Here, we report that chromodomain helicase DNA-binding protein 4 (CHD4) is a novel BRIT1 binding partner that regulates the HR repair process. The BRCA1 C-terminal domains of BRIT1 are required for its interaction with CHD4. Depletion of CHD4 and overexpression of the ATPase-dead form of CHD4 impairs the recruitment of BRIT1 to the DNA damage lesions. As a functional consequence, CHD4 deficiency sensitizes cells to double strand break-inducing agents, reduces the recruitment of HR repair factor BRCA1, and impairs HR repair efficiency. We further demonstrate that CHD4-depleted cells are more sensitive to poly(ADP-ribose) polymerase inhibitor treatment. In response to DNA damage induced by poly(ADP-ribose) polymerase inhibitors, CHD4 deficiency impairs the recruitment of DNA repair proteins BRIT1, BRCA1, and replication protein A at early steps of HR repair. Taken together, our findings identify an important role of CHD4 in controlling HR repair to maintain genome stability and establish the potential therapeutic implications of targeting CHD4 deficiency in tumors.
Authors	Mei-Ren Pan, Hui-Ju Hsieh, Hui Dai, Wen-Chun Hung, Kaiyi Li, Guang Peng, Shiaw-Yih Lin
Journal	The Journal of biological chemistry (J Biol Chem) Vol. 287 Issue 9 Pg. 6764-72 (Feb 24 2012) ISSN: 1083-351X [Electronic] United States
PMID	22219182 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, U.S. Gov't, Non-P.H.S.)
Chemical References	Autoantigens BRCA1 Protein BRCA1 protein, human CHD4 protein, human Cell Cycle Proteins Chromatin Cytoskeletal Proteins MCPH1 protein, human Nerve Tissue Proteins Phthalazines Piperazines Poly(ADP-ribose) Polymerase Inhibitors RNA, Small Interfering RPA1 protein, human Replication Protein A Poly Adenosine Diphosphate Ribose PARP1 protein, human Poly (ADP-Ribose) Polymerase-1 Poly(ADP-ribose) Polymerases Mi-2 Nucleosome Remodeling and Deacetylase Complex olaparib
Topics	Autoantigens (genetics, metabolism) BRCA1 Protein (metabolism) Breast (cytology) Breast Neoplasms Cell Cycle Proteins Cell Line Chromatin (physiology) Cytoskeletal Proteins DNA Damage (physiology) DNA Repair (physiology) Female Homologous Recombination (drug effects, physiology) Humans Mi-2 Nucleosome Remodeling and Deacetylase Complex (deficiency, genetics, metabolism) Nerve Tissue Proteins (metabolism) Phthalazines (pharmacology) Piperazines (pharmacology) Poly (ADP-Ribose) Polymerase-1 Poly Adenosine Diphosphate Ribose (metabolism) Poly(ADP-ribose) Polymerase Inhibitors Poly(ADP-ribose) Polymerases (metabolism) RNA, Small Interfering (pharmacology) Replication Protein A (metabolism)

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