title: Regulation of 53BP1 protein stability by RNF8 and RNF168 is important for efficient DNA double-strand break repair.
abstract: 53BP1 regulates DNA double-strand break (DSB) repair. In functional assays for specific DSB repair pathways, we found that 53BP1 was important in the conservative non-homologous end-joining (C-NHEJ) pathway, and this activity was dependent upon RNF8 and RNF168. We observed that 53BP1 protein was diffusely abundant in nuclei, and upon ionizing radiation, 53BP1 was everywhere degraded except at DNA damage sites. Depletion of RNF8 or RNF168 blocked the degradation of the diffusely localized nuclear 53BP1, and ionizing radiation induced foci (IRIF) did not form. Furthermore, when 53BP1 degradation was inhibited, a subset of 53BP1 was bound to DNA damage sites but bulk, unbound 53BP1 remained in the nucleoplasm, and localization of its downstream effector RIF1 at DSBs was abolished. Our data suggest a novel mechanism for responding to DSB that upon ionizing radiation, 53BP1 was divided into two populations, ensuring functional DSB repair: damage site-bound 53BP1 whose binding signal is known to be generated by RNF8 and RNF168; and unbound bulk 53BP1 whose ensuing degradation is regulated by RNF8 and RNF168.
authors.affiliation: Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio, United States of America.
authors.forename: Yiheng
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio, United States of America.
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio, United States of America.
authors.forename: Kun
authors.initials: K
authors.lastname: Huang
authors.affiliation: Department of Radiation Oncology, The Ohio State University, Columbus, Ohio, United States of America.
authors.forename: Fen
authors.initials: F
authors.lastname: Xia
authors.affiliation: Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio, United States of America.
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Parvin
authors.affiliation: School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Neelima
authors.initials: N
authors.lastname: Mondal
mesh_terms: D053903:DNA Breaks, Double-Stranded; D059766:DNA End-Joining Repair; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D055550:Protein Stability; D021381:Protein Transport; D059748:Proteolysis; D034501:Telomere-Binding Proteins / Q000378:metabolism; D000071857:Tumor Suppressor p53-Binding Protein 1; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; C486521:RNF8 protein, human; C492743:Rif1 protein, human; C498301:TP53BP1 protein, human; D034501:Telomere-Binding Proteins; D000071857:Tumor Suppressor p53-Binding Protein 1; C535210:RNF168 protein, human; D044767:Ubiquitin-Protein Ligases