title: Non-canonical Bromodomain within DNA-PKcs Promotes DNA Damage Response and Radioresistance through Recognizing an IR-Induced Acetyl-Lysine on H2AX.
abstract: Regulatory mechanisms underlying γH2AX induction and the associated cell fate decision during DNA damage response (DDR) remain obscure. Here, we discover a bromodomain (BRD)-like module in DNA-PKcs (DNA-PKcs-BRD) that specifically recognizes H2AX acetyl-lysine 5 (K5ac) for sequential induction of γH2AX and concurrent cell fate decision(s). First, top-down mass spectrometry of radiation-phenotypic, full-length H2AX revealed a radiation-inducible, K5ac-dependent induction of γH2AX. Combined approaches of sequence-structure modeling/docking, site-directed mutagenesis, and biochemical experiments illustrated that through docking on H2AX K5ac, this non-canonical BRD determines not only the H2AX-targeting activity of DNA-PKcs but also the over-activation of DNA-PKcs in radioresistant tumor cells, whereas a Kac antagonist, JQ1, was able to bind to DNA-PKcs-BRD, leading to re-sensitization of tumor cells to radiation. This study elucidates the mechanism underlying the H2AX-dependent regulation of DNA-PKcs in ionizing radiation-induced, differential DDR, and derives an unconventional, non-catalytic domain target in DNA-PKs for overcoming resistance during cancer radiotherapy.
authors.affiliation: Department of Chemistry & Institutes of Biomedical Sciences, Fudan University, Shanghai 20032, China; Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
authors.forename: Ling
authors.initials: L
authors.lastname: Xie
authors.affiliation: Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Program in Molecular & Cellular Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
authors.forename: Srinivas
authors.initials: S
authors.lastname: Ramachandran
authors.affiliation: Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
authors.forename: YuanYu
authors.initials: Y
authors.lastname: Lee
authors.affiliation: Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; College of Public Health, Zhengzhou University, Zhengzhou 450001, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Yan
authors.affiliation: Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Krajewski
authors.affiliation: Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Medicinal Chemistry, Soochow University, Suzhou 215123, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Liu
authors.affiliation: Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhu
authors.affiliation: Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Chen
authors.affiliation: Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Strahl
authors.affiliation: Departments of Structural and Chemical Biology, Icahn School of Medicine at Mount Sinai, NY 10029, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Jin
authors.affiliation: Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Program in Molecular & Cellular Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. Electronic address: dokh@unc.edu.
authors.forename: Nikolay V
authors.initials: NV
authors.lastname: Dokholyan
authors.affiliation: Department of Chemistry & Institutes of Biomedical Sciences, Fudan University, Shanghai 20032, China; Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Program in Molecular & Cellular Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. Electronic address: xianc@email.unc.edu.
authors.forename: Xian
authors.initials: X
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D045744:Cell Line, Tumor; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D051747:DNA-Activated Protein Kinase / Q000737:chemistry* / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D057809:HEK293 Cells; D006367:HeLa Cells; D006657:Histones / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D020014:K562 Cells; D008239:Lysine / Q000378:metabolism; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism*; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D011836:Radiation Tolerance
chemical_list: D004268:DNA-Binding Proteins; C468783:H2AX protein, human; D006657:Histones; D009687:Nuclear Proteins; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D008239:Lysine