title: RAD18 promotes DNA double-strand break repair during G1 phase through chromatin retention of 53BP1.
abstract: Recruitment of RAD18 to stalled replication forks facilitates monoubiquitination of PCNA during S-phase, promoting translesion synthesis at sites of UV irradiation-induced DNA damage. In this study, we show that RAD18 is also recruited to ionizing radiation (IR)-induced sites of DNA double-strand breaks (DSBs) forming foci which are co-localized with 53BP1, NBS1, phosphorylated ATM, BRCA1 and gamma-H2AX. RAD18 associates with 53BP1 and is recruited to DSB sites in a 53BP1-dependent manner specifically during G1-phase, RAD18 monoubiquitinates KBD domain of 53BP1 at lysine 1268 in vitro. A monoubiquitination-resistant 53BP1 mutant harboring a substitution at lysine 1268 is not retained efficiently at the chromatin in the vicinity of DSBs. In Rad18-null cells, retention of 53BP1 foci, efficiency of DSB repair and post-irradiation viability are impaired compared with wild-type cells. Taken together, these results suggest that RAD18 promotes 53BP1-directed DSB repair by enhancing retention of 53BP1, possibly through an interaction between RAD18 and 53BP1 and the modification of 53BP1.
authors.affiliation: Cell Genetics, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto 860-0811, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Watanabe
authors.forename: Kuniyoshi
authors.initials: K
authors.lastname: Iwabuchi
authors.forename: Jinghua
authors.initials: J
authors.lastname: Sun
authors.forename: Yuri
authors.initials: Y
authors.lastname: Tsuji
authors.forename: Tokio
authors.initials: T
authors.lastname: Tani
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Tokunaga
authors.forename: Takayasu
authors.initials: T
authors.lastname: Date
authors.forename: Mitsumasa
authors.initials: M
authors.lastname: Hashimoto
authors.forename: Masaru
authors.initials: M
authors.lastname: Yamaizumi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tateishi
mesh_terms: D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism / Q000528:radiation effects; D002843:Chromatin / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D044127:Epigenesis, Genetic; D016193:G1 Phase / Q000235:genetics* / Q000528:radiation effects; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D000071857:Tumor Suppressor p53-Binding Protein 1; D044763:Ubiquitin-Conjugating Enzymes / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases; D054875:Ubiquitination; D016335:Zinc Fingers
chemical_list: D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; C485954:RAD18 protein, human; C485953:Rad18 protein, mouse; C498301:TP53BP1 protein, human; C498302:Trp53bp1 protein, mouse; D000071857:Tumor Suppressor p53-Binding Protein 1; D044763:Ubiquitin-Conjugating Enzymes; D044767:Ubiquitin-Protein Ligases