title: Nucleolin participates in DNA double-strand break-induced damage response through MDC1-dependent pathway.
abstract: H2AX is an important factor for chromatin remodeling to facilitate accumulation of DNA damage-related proteins at DNA double-strand break (DSB) sites. In order to further understand the role of H2AX in the DNA damage response (DDR), we attempted to identify H2AX-interacting proteins by proteomics analysis. As a result, we identified nucleolin as one of candidates. Here, we show a novel role of a major nucleolar protein, nucleolin, in DDR. Nucleolin interacted with γ-H2AX and accumulated to laser micro-irradiated DSB damage sites. Chromatin Immunoprecipitation assay also displayed the accumulation of nucleolin around DSB sites. Nucleolin-depleted cells exhibited repression of both ATM-dependent phosphorylation following exposure to γ-ray and subsequent cell cycle checkpoint activation. Furthermore, nucleolin-knockdown reduced HR and NHEJ activity and showed decrease in IR-induced chromatin accumulation of HR/NHEJ factors, agreeing with the delayed kinetics of γ-H2AX focus. Moreover, nucleolin-knockdown decreased MDC1-related events such as focus formation of 53 BP1, RNF168, phosphorylated ATM, and H2A ubiquitination. Nucleolin also showed FACT-like activity for DSB damage-induced histone eviction from chromatin. Taken together, nucleolin could promote both ATM-dependent cell cycle checkpoint and DSB repair by functioning in an MDC1-related pathway through its FACT-like function.
authors.affiliation: Department of Genome Repair Dynamics, Radiation Biology Center, Kyoto University, Kyoto, Japan. jkobayashi@house.rbc.kyoto-u.ac.jp
authors.forename: Junya
authors.initials: J
authors.lastname: Kobayashi
authors.forename: Hiroko
authors.initials: H
authors.lastname: Fujimoto
authors.forename: Jun
authors.initials: J
authors.lastname: Sato
authors.forename: Ikue
authors.initials: I
authors.lastname: Hayashi
authors.forename: Sandeep
authors.initials: S
authors.lastname: Burma
authors.forename: Shinya
authors.initials: S
authors.lastname: Matsuura
authors.forename: David J
authors.initials: DJ
authors.lastname: Chen
authors.forename: Kenshi
authors.initials: K
authors.lastname: Komatsu
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D059447:Cell Cycle Checkpoints; D018797:Cell Cycle Proteins; D002843:Chromatin / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair / Q000502:physiology*; D005720:Gamma Rays; D055785:Gene Knockdown Techniques; D006367:HeLa Cells; D006657:Histones / Q000378:metabolism / Q000502:physiology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D009687:Nuclear Proteins / Q000378:metabolism / Q000502:physiology*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010766:Phosphorylation; D040901:Proteomics; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015534:Trans-Activators / Q000378:metabolism / Q000502:physiology*; D054875:Ubiquitination; D000097796:Nucleolin
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D002843:Chromatin; D006657:Histones; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; D016601:RNA-Binding Proteins; D015534:Trans-Activators; D000097796:Nucleolin; C468783:H2AX protein, human; C413163:MDC1 protein, human; C508937:MDC1 protein, mouse