title: MDC1 regulates intra-S-phase checkpoint by targeting NBS1 to DNA double-strand breaks.
abstract: The product of the Nijmegen breakage syndrome gene (NBS1) plays crucial roles in DNA damage response through its association with many proteins, including MRE11 and RAD50. However, it remains to be determined exactly how NBS1 accumulates at or near DNA double-strand breaks. Here we report that MDC1 directly binds to NBS1 and targets NBS1 to the sites of DNA damage. The MDC1-NBS1 interaction occurs through a specific region (residues 200-420) of MDC1, which contains multiple consensus casein kinase 2 (CK2) phosphorylation sites. In addition, this interaction requires both the forkhead-associated (FHA) and tandem BRCA1 C-terminal (BRCT) domains of NBS1. Disruption of the MDC1-NBS1 interaction results in failure of NBS1 accumulation at DNA double-strand breaks and impairment of intra-S checkpoint activation. These studies provide important mechanistic insights as to how MDC1 regulates NBS1 and the intra-S-phase checkpoint in response to DNA damage.
authors.affiliation: Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA.
authors.forename: Liming
authors.initials: L
authors.lastname: Wu
authors.forename: Kuntian
authors.initials: K
authors.lastname: Luo
authors.forename: Zhenkun
authors.initials: Z
authors.lastname: Lou
authors.forename: Junjie
authors.initials: J
authors.lastname: Chen
mesh_terms: D017766:Acid Anhydride Hydrolases; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D047390:Casein Kinase II / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D053903:DNA Breaks, Double-Stranded; D045643:DNA Repair Enzymes / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D000076228:MRE11 Homologue Protein; D051379:Mice; D018345:Mice, Knockout; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D017434:Protein Structure, Tertiary / Q000235:genetics; D016196:S Phase / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C413163:MDC1 protein, human; C121766:MRE11 protein, human; C112156:NBN protein, human; D009687:Nuclear Proteins; D015534:Trans-Activators; D047390:Casein Kinase II; D000076228:MRE11 Homologue Protein; D017766:Acid Anhydride Hydrolases; C112158:RAD50 protein, human; D045643:DNA Repair Enzymes