title: Chk2-dependent phosphorylation of XRCC1 in the DNA damage response promotes base excision repair.
abstract: The DNA damage response (DDR) has an essential function in maintaining genomic stability. Ataxia telangiectasia-mutated (ATM)-checkpoint kinase 2 (Chk2) and ATM- and Rad3-related (ATR)-Chk1, triggered, respectively, by DNA double-strand breaks and blocked replication forks, are two major DDRs processing structurally complicated DNA damage. In contrast, damage repaired by base excision repair (BER) is structurally simple, but whether, and how, the DDR is involved in repairing this damage is unclear. Here, we demonstrated that ATM-Chk2 was activated in the early response to oxidative and alkylation damage, known to be repaired by BER. Furthermore, Chk2 formed a complex with XRCC1, the BER scaffold protein, and phosphorylated XRCC1 in vivo and in vitro at Thr(284). A mutated XRCC1 lacking Thr(284) phosphorylation was linked to increased accumulation of unrepaired BER intermediate, reduced DNA repair capacity, and higher sensitivity to alkylation damage. In addition, a phosphorylation-mimic form of XRCC1 showed increased interaction with glycosylases, but not other BER proteins. Our results are consistent with the phosphorylation of XRCC1 by ATM-Chk2 facilitating recruitment of downstream BER proteins to the initial damage recognition/excision step to promote BER.
authors.affiliation: Institute of Public Health, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Wen-Cheng
authors.initials: WC
authors.lastname: Chou
authors.forename: Hui-Chun
authors.initials: HC
authors.lastname: Wang
authors.forename: Fen-Hwa
authors.initials: FH
authors.lastname: Wong
authors.forename: Shian-ling
authors.initials: SL
authors.lastname: Ding
authors.forename: Pei-Ei
authors.initials: PE
authors.lastname: Wu
authors.forename: Sheau-Yann
authors.initials: SY
authors.lastname: Shieh
authors.forename: Chen-Yang
authors.initials: CY
authors.lastname: Shen
mesh_terms: D000477:Alkylating Agents / Q000633:toxicity; D045744:Cell Line, Tumor; D064447:Checkpoint Kinase 2; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000378:metabolism; D016877:Oxidants / Q000633:toxicity; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D000076105:X-ray Repair Cross Complementing Protein 1
chemical_list: D000477:Alkylating Agents; D004268:DNA-Binding Proteins; D050505:Mutant Proteins; D016877:Oxidants; D000076105:X-ray Repair Cross Complementing Protein 1; C000619371:XRCC1 protein, human; D064447:Checkpoint Kinase 2; C578634:CHEK2 protein, human; D017346:Protein Serine-Threonine Kinases