title: DEAD Box 1 Facilitates Removal of RNA and Homologous Recombination at DNA Double-Strand Breaks.
abstract: Although RNA and RNA-binding proteins have been linked to double-strand breaks (DSBs), little is known regarding their roles in the cellular response to DSBs and, if any, in the repair process. Here, we provide direct evidence for the presence of RNA-DNA hybrids at DSBs and suggest that binding of RNA to DNA at DSBs may impact repair efficiency. Our data indicate that the RNA-unwinding protein DEAD box 1 (DDX1) is required for efficient DSB repair and cell survival after ionizing radiation (IR), with depletion of DDX1 resulting in reduced DSB repair by homologous recombination (HR). While DDX1 is not essential for end resection, a key step in homology-directed DSB repair, DDX1 is required for maintenance of the single-stranded DNA once generated by end resection. We show that transcription deregulation has a significant effect on DSB repair by HR in DDX1-depleted cells and that RNA-DNA duplexes are elevated at DSBs in DDX1-depleted cells. Based on our combined data, we propose a role for DDX1 in resolving RNA-DNA structures that accumulate at DSBs located at sites of active transcription. Our findings point to a previously uncharacterized requirement for clearing RNA at DSBs for efficient repair by HR.
authors.affiliation: Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton, Alberta, Canada.
authors.forename: Lei
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton, Alberta, Canada.
authors.forename: Devon R
authors.initials: DR
authors.lastname: Germain
authors.affiliation: Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton, Alberta, Canada.
authors.forename: Ho-Yin
authors.initials: HY
authors.lastname: Poon
authors.affiliation: Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton, Alberta, Canada.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Hildebrandt
authors.affiliation: Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton, Alberta, Canada.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Monckton
authors.affiliation: Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton, Alberta, Canada.
authors.forename: Darin
authors.initials: D
authors.lastname: McDonald
authors.affiliation: Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton, Alberta, Canada.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Hendzel
authors.affiliation: Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton, Alberta, Canada rgodbout@ualberta.ca.
authors.forename: Roseline
authors.initials: R
authors.lastname: Godbout
mesh_terms: D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism*; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D005786:Gene Expression Regulation; D006367:HeLa Cells; D059765:Homologous Recombination; D006801:Humans; D012313:RNA / Q000378:metabolism*; D014158:Transcription, Genetic / Q000528:radiation effects
chemical_list: D012313:RNA; C086252:DDX1 protein, human; D053487:DEAD-box RNA Helicases