A role for human homologous recombination factors in suppressing microhomology-mediated end joining

DNA double-strand breaks (DSBs) are toxic lesions, which if improperly repaired can result in cell death or genomic instability. DSB repair is usually facilitated by the classical non-homologous end joining (C-NHEJ), or homologous recombination (HR) pathways. However, a mutagenic alternative NHEJ pa...

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Veröffentlicht in:	Nucleic acids research Jg. 44; H. 12; S. 5743 - 5757
Hauptverfasser:	Ahrabi, Sara, Sarkar, Sovan, Pfister, Sophia X., Pirovano, Giacomo, Higgins, Geoff S., Porter, Andrew C.G., Humphrey, Timothy C.
Format:	Journal Article
Sprache:	Englisch
Veröffentlicht:	England Oxford University Press 08.07.2016
Schlagworte:	Base Sequence Biological Assay BRCA1 Protein - antagonists & inhibitors BRCA1 Protein - genetics BRCA1 Protein - metabolism BRCA2 Protein - antagonists & inhibitors BRCA2 Protein - genetics BRCA2 Protein - metabolism Carrier Proteins - genetics Carrier Proteins - metabolism Cell Line, Tumor DNA - metabolism DNA Breaks, Double-Stranded DNA End-Joining Repair DNA Polymerase theta DNA-Binding Proteins - genetics DNA-Binding Proteins - metabolism DNA-Directed DNA Polymerase - genetics DNA-Directed DNA Polymerase - metabolism Endodeoxyribonucleases Epithelial Cells - cytology Epithelial Cells - metabolism Fibroblasts - cytology Fibroblasts - metabolism Genome Integrity, Repair and Humans MRE11 Homologue Protein Mutation Nuclear Proteins - genetics Nuclear Proteins - metabolism Osteoblasts - cytology Osteoblasts - metabolism Poly(ADP-ribose) Polymerases - genetics Poly(ADP-ribose) Polymerases - metabolism Recombinational DNA Repair Replication Protein A - antagonists & inhibitors Replication Protein A - genetics Replication Protein A - metabolism RNA, Small Interfering - genetics RNA, Small Interfering - metabolism Sequence Alignment Sequence Homology, Nucleic Acid
ISSN:	0305-1048, 1362-4962
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Zusammenfassung:	DNA double-strand breaks (DSBs) are toxic lesions, which if improperly repaired can result in cell death or genomic instability. DSB repair is usually facilitated by the classical non-homologous end joining (C-NHEJ), or homologous recombination (HR) pathways. However, a mutagenic alternative NHEJ pathway, microhomology-mediated end joining (MMEJ), can also be deployed. While MMEJ is suppressed by C-NHEJ, the relationship between HR and MMEJ is less clear. Here, we describe a role for HR genes in suppressing MMEJ in human cells. By monitoring DSB mis-repair using a sensitive HPRT assay, we found that depletion of HR proteins, including BRCA2, BRCA1 or RPA, resulted in a distinct mutational signature associated with significant increases in break-induced mutation frequencies, deletion lengths and the annealing of short regions of microhomology (2-6 bp) across the break-site. This signature was dependent on CtIP, MRE11, POLQ and PARP, and thus indicative of MMEJ. In contrast to CtIP or MRE11, depletion of BRCA1 resulted in increased partial resection and MMEJ, thus revealing a functional distinction between these early acting HR factors. Together these findings indicate that HR factors suppress mutagenic MMEJ following DSB resection.
Bibliographie:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0305-1048 1362-4962
DOI:	10.1093/nar/gkw326