title: ATM-mediated phosphorylation of the chromatin remodeling enzyme BRG1 modulates DNA double-strand break repair.
abstract: ATP-dependent chromatin remodeling complexes such as SWI/SNF (SWItch/Sucrose NonFermentable) have been implicated in DNA double-strand break (DSB) repair and damage responses. However, the regulatory mechanisms that control the function of chromatin remodelers in DNA damage response are largely unknown. Here, we show that ataxia telangiectasia mutated (ATM) mediates the phosphorylation of BRG1, the catalytic ATPase of the SWI/SNF complex that contributes to DSB repair by binding γ-H2AX-containing nucleosomes via interaction with acetylated histone H3 and stimulating γ-H2AX formation, at Ser-721 in response to DNA damage. ATM-mediated phosphorylation of BRG1 occurs rapidly and transiently after DNA damage. Phosphorylated BRG1 binds γ-H2AX-containing nucleosomes to form the repair foci. The Ser-721 phosphorylation of BRG1 is critical for binding γ-H2AX-containing nucleosomes and stimulating γ-H2AX formation and DSB repair. BRG1 binds to acetylated H3 peptides much better after phosphorylation at Ser-721 by DNA damage. However, the phosphorylation of Ser-721 does not significantly affect the ATPase and transcriptional activities of BRG1. These results, establishing BRG1 as a novel and functional ATM substrate, suggest that the ATM-mediated phosphorylation of BRG1 facilitates DSB repair by stimulating the association of this remodeler with γ-H2AX nucleosomes via enhancing the affinity to acetylated H3. Our work also suggests that the mechanism of BRG1 stimulation of DNA repair is independent of the remodeler's enzymatic or transcriptional activities.
authors.affiliation: Department of Life Science, College of Natural Sciences, The Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, Republic of Korea.
authors.forename: S-J
authors.initials: SJ
authors.lastname: Kwon
authors.affiliation: Department of Life Science, College of Natural Sciences, The Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, Republic of Korea.
authors.forename: J-H
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Life Science, College of Natural Sciences, The Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, Republic of Korea.
authors.forename: E-J
authors.initials: EJ
authors.lastname: Park
authors.affiliation: Department of Life Science, College of Natural Sciences, The Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, Republic of Korea.
authors.forename: S-A
authors.initials: SA
authors.lastname: Lee
authors.affiliation: Department of Life Science, College of Natural Sciences, The Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, Republic of Korea.
authors.forename: H-S
authors.initials: HS
authors.lastname: Lee
authors.affiliation: Department of Life Science, College of Natural Sciences, The Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, Republic of Korea.
authors.forename: S W
authors.initials: SW
authors.lastname: Kang
authors.affiliation: Department of Life Science, College of Natural Sciences, The Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, Republic of Korea.
authors.forename: J
authors.initials: J
authors.lastname: Kwon
mesh_terms: D000107:Acetylation; D064007:Ataxia Telangiectasia Mutated Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D042002:Chromatin Assembly and Disassembly; D053903:DNA Breaks, Double-Stranded; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism*; D004260:DNA Repair; D057809:HEK293 Cells; D006367:HeLa Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D018613:Microscopy, Confocal; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D009707:Nucleosomes / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D034622:RNA Interference; D012694:Serine / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: C468783:H2AX protein, human; D006657:Histones; D009687:Nuclear Proteins; D009707:Nucleosomes; D014157:Transcription Factors; D012694:Serine; D064007:Ataxia Telangiectasia Mutated Proteins; C084108:SMARCA4 protein, human; D004265:DNA Helicases