title: INT6/EIF3E Controls the RNF8-Dependent Ubiquitylation Pathway and Facilitates DNA Double-Strand Break Repair in Human Cells.
abstract: Unrepaired DNA double-strand breaks (DSB) are the most destructive chromosomal lesions driving genomic instability, a core hallmark of cancer. Here, we identify the antioncogenic breast cancer factor INT6/EIF3E as an essential regulator of DSB repair that promotes homologous recombination (HR)-mediated repair and, to a lesser extent, nonhomologous end-joining repair. INT6 silencing impaired the accrual of the ubiquitin ligase RNF8 at DSBs and the formation of ubiquitin conjugates at DSB sites, especially Lys63-linked polyubiquitin chains, resulting in impaired recruitment of BRCA1, BRCA2, and RAD51, which are all involved in HR repair. In contrast, INT6 deficiency did not affect the accumulation of RNF168, 53BP1, or RPA at DSBs. In INT6-silenced cells, there was also an alteration in DNA damage-induced localization of MDC1, a key target for ATM phosphorylation, which is a prerequisite for RNF8 recruitment. The attenuated DNA damage localization of RNF8 resulting from INT6 depletion could be attributed to the defective retention of ATM previously reported by us. Our findings deepen insights into how INT6 protects against breast cancer by showing how it functions in DSB repair, with potential clinical implications for cancer therapy. Cancer Res; 76(20); 6054-65. ©2016 AACR.
authors.affiliation: Laboratory of Biology and Modelling of the Cell, CNRS UMR 5239, INSERM U1210, ENS de Lyon, University of Lyon, Lyon, France.
authors.forename: Christelle
authors.initials: C
authors.lastname: Morris
authors.affiliation: Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas.
authors.forename: Nozomi
authors.initials: N
authors.lastname: Tomimatsu
authors.affiliation: Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas.
authors.forename: Sandeep
authors.initials: S
authors.lastname: Burma
authors.affiliation: Laboratory of Biology and Modelling of the Cell, CNRS UMR 5239, INSERM U1210, ENS de Lyon, University of Lyon, Lyon, France. pjalinot@ens-lyon.fr.
authors.forename: Pierre
authors.initials: P
authors.lastname: Jalinot
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism; D024682:BRCA2 Protein / Q000502:physiology; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism; D018797:Cell Cycle Proteins; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000502:physiology*; D039621:Eukaryotic Initiation Factor-3 / Q000502:physiology*; D005260:Female; D006367:HeLa Cells; D059765:Homologous Recombination; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism; D051135:Rad51 Recombinase / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases; D054875:Ubiquitination
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D024682:BRCA2 Protein; C551750:BRCA2 protein, human; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D039621:Eukaryotic Initiation Factor-3; C413163:MDC1 protein, human; D009687:Nuclear Proteins; C486521:RNF8 protein, human; D015534:Trans-Activators; D044767:Ubiquitin-Protein Ligases; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C495153:RAD51 protein, human; D051135:Rad51 Recombinase