The RNF138 E3 ligase displaces Ku to promote DNA end resection and regulate DNA repair pathway choice

SUMMARYDNA double-strand breaks (DSBs) can be repaired by two major pathways: non-homologous end-joining (NHEJ) and homologous recombination (HR). DNA repair pathway choice is governed by the opposing activities of 53BP1, in complex with its effectors RIF1 and REV7, and BRCA1. However, it remains unknown how the 53BP1/RIF1/REV7 complex stimulates NHEJ and restricts HR to the S/G2 phases of the cell cycle. Using a mass spectrometry (MS)-based approach, we identify 11 high-confidence REV7 interactors and elucidate the role of a previously undescribed factor, FAM35A/SHDL2, as a novel effector of REV7 in the NHEJ pathway. FAM35A depletion impairs NHEJ-mediated DNA repair and compromises antibody diversification by class switch recombination (CSR) in B-cells. FAM35A accumulates at DSBs in a 53BP1-, RIF1- and REV7-dependent manner and antagonizes HR by limiting DNA end resection. In fact, FAM35A is part of a larger complex composed of REV7 and another previously uncharacterized protein, C20orf196/SHDL1, which promotes NHEJ and limits HR. Together, these results establish FAM35A as a novel effector of REV7 in controlling the decision-making process during DSB repair.

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CSB interacts with BRCA1 in late S/G2 to promote MRN- and CtIP-mediated DNA end resection

Nucleic Acids Research ◽

10.1093/nar/gkz784 ◽

2019 ◽

Vol 47 (20) ◽

pp. 10678-10692 ◽

Cited By ~ 4

Author(s):

Nicole L Batenburg ◽

John R Walker ◽

Yan Coulombe ◽

Alana Sherker ◽

Jean-Yves Masson ◽

...

Keyword(s):

S Phase ◽

Repair Pathway ◽

Dsb Repair ◽

Support Cell ◽

A Cell ◽

G2 Phase ◽

Pathway Choice ◽

Dna End Resection ◽

C Complex ◽

End Resection

Abstract CSB, a member of the SWI2/SNF2 superfamily, has been implicated in evicting histones to promote the DSB pathway choice towards homologous recombination (HR) repair. However, how CSB promotes HR repair remains poorly characterized. Here we demonstrate that CSB interacts with both MRE11/RAD50/NBS1 (MRN) and BRCA1 in a cell cycle regulated manner, with the former requiring its WHD and occurring predominantly in early S phase. CSB interacts with the BRCT domain of BRCA1 and this interaction is regulated by CDK-dependent phosphorylation of CSB on S1276. The CSB–BRCA1 interaction, which peaks in late S/G2 phase, is responsible for mediating the interaction of CSB with the BRCA1-C complex consisting of BRCA1, MRN and CtIP. While dispensable for histone eviction at DSBs, CSB phosphorylation on S1276 is necessary to promote efficient MRN- and CtIP-mediated DNA end resection, thereby restricting NHEJ and enforcing the DSB repair pathway choice to HR. CSB phosphorylation on S1276 is also necessary to support cell survival in response to DNA damage-inducing agents. These results altogether suggest that CSB interacts with BRCA1 to promote DNA end resection for HR repair and that although prerequisite, CSB-mediated histone eviction alone is insufficient to promote the pathway choice towards HR.

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MAD2L2 dimerization and TRIP13 control shieldin activity in DNA repair

Nature Communications ◽

10.1038/s41467-021-25724-y ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Inge de Krijger ◽

Bastian Föhr ◽

Santiago Hernández Pérez ◽

Estelle Vincendeau ◽

Judit Serrat ◽

...

Keyword(s):

Dna Repair ◽

Strand Break ◽

Double Strand Break Repair ◽

Stable Complex ◽

Repair Pathway ◽

C Terminus ◽

Dna Double Strand Break ◽

Domain Protein ◽

Dna End Resection ◽

End Resection

AbstractMAD2L2 (REV7) plays an important role in DNA double-strand break repair. As a member of the shieldin complex, consisting of MAD2L2, SHLD1, SHLD2 and SHLD3, it controls DNA repair pathway choice by counteracting DNA end-resection. Here we investigated the requirements for shieldin complex assembly and activity. Besides a dimerization-surface, HORMA-domain protein MAD2L2 has the extraordinary ability to wrap its C-terminus around SHLD3, likely creating a very stable complex. We show that appropriate function of MAD2L2 within shieldin requires its dimerization, mediated by SHLD2 and accelerating MAD2L2-SHLD3 interaction. Dimerization-defective MAD2L2 impairs shieldin assembly and fails to promote NHEJ. Moreover, MAD2L2 dimerization, along with the presence of SHLD3, allows shieldin to interact with the TRIP13 ATPase, known to drive topological switches in HORMA-domain proteins. We find that appropriate levels of TRIP13 are important for proper shieldin (dis)assembly and activity in DNA repair. Together our data provide important insights in the dependencies for shieldin activity.

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Repair pathway choice for double-strand breaks

Essays in Biochemistry ◽

10.1042/ebc20200007 ◽

2020 ◽

Vol 64 (5) ◽

pp. 765-777 ◽

Cited By ~ 2

Author(s):

Yixi Xu ◽

Dongyi Xu

Keyword(s):

Cell Cycle ◽

Double Strand Breaks ◽

Homologous Region ◽

Gene Repair ◽

Repair Pathway ◽

Dna Double Strand Breaks ◽

Environmental Radiation ◽

Strand Breaks ◽

Dna End Resection ◽

End Resection

Abstract Deoxyribonucleic acid (DNA) is at a constant risk of damage from endogenous substances, environmental radiation, and chemical stressors. DNA double-strand breaks (DSBs) pose a significant threat to genomic integrity and cell survival. There are two major pathways for DSB repair: nonhomologous end-joining (NHEJ) and homologous recombination (HR). The extent of DNA end resection, which determines the length of the 3′ single-stranded DNA (ssDNA) overhang, is the primary factor that determines whether repair is carried out via NHEJ or HR. NHEJ, which does not require a 3′ ssDNA tail, occurs throughout the cell cycle. 53BP1 and the cofactors PTIP or RIF1-shieldin protect the broken DNA end, inhibit long-range end resection and thus promote NHEJ. In contrast, HR mainly occurs during the S/G2 phase and requires DNA end processing to create a 3′ tail that can invade a homologous region, ensuring faithful gene repair. BRCA1 and the cofactors CtIP, EXO1, BLM/DNA2, and the MRE11–RAD50–NBS1 (MRN) complex promote DNA end resection and thus HR. DNA resection is influenced by the cell cycle, the chromatin environment, and the complexity of the DNA end break. Herein, we summarize the key factors involved in repair pathway selection for DSBs and discuss recent related publications.

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Faculty Opinions recommendation of A cell cycle-dependent regulatory circuit composed of 53BP1-RIF1 and BRCA1-CtIP controls DNA repair pathway choice.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.717972354.793478994 ◽

2013 ◽

Author(s):

Carol MacKintosh

Keyword(s):

Cell Cycle ◽

Dna Repair ◽

Repair Pathway ◽

Regulatory Circuit ◽

A Cell ◽

Pathway Choice ◽

Cycle Dependent

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SAMHD1 Promotes DNA End Resection to Facilitate DNA Repair by Homologous Recombination

Cell Reports ◽

10.1016/j.celrep.2017.08.008 ◽

2017 ◽

Vol 20 (8) ◽

pp. 1921-1935 ◽

Cited By ~ 65

Author(s):

Waaqo Daddacha ◽

Allyson E. Koyen ◽

Amanda J. Bastien ◽

PamelaSara E. Head ◽

Vishal R. Dhere ◽

...

Keyword(s):

Dna Repair ◽

Homologous Recombination ◽

Dna End Resection ◽

End Resection

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Epigenetic Regulation of DNA Repair Pathway Choice by MacroH2A1 Splice Variants Ensures Genome Stability

Molecular Cell ◽

10.1016/j.molcel.2020.06.028 ◽

2020 ◽

Vol 79 (5) ◽

pp. 836-845.e7 ◽

Cited By ~ 1

Author(s):

Robin Sebastian ◽

Eri K. Hosogane ◽

Eric G. Sun ◽

Andy D. Tran ◽

William C. Reinhold ◽

...

Keyword(s):

Dna Repair ◽

Epigenetic Regulation ◽

Genome Stability ◽

Splice Variants ◽

Repair Pathway ◽

Pathway Choice

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A role for the p53 tumour suppressor in regulating the balance between homologous recombination and non-homologous end joining

Open Biology ◽

10.1098/rsob.160225 ◽

2016 ◽

Vol 6 (9) ◽

pp. 160225 ◽

Cited By ~ 16

Author(s):

Sylvie Moureau ◽

Janna Luessing ◽

Emma Christina Harte ◽

Muriel Voisin ◽

Noel Francis Lowndes

Keyword(s):

Dna Damage ◽

Homologous Recombination ◽

Tumour Suppressor ◽

Cycle Phase ◽

Repair Pathway ◽

End Joining ◽

Dsb Repair ◽

Pathway Choice ◽

Non Homologous End Joining ◽

End Resection

Loss of p53, a transcription factor activated by cellular stress, is a frequent event in cancer. The role of p53 in tumour suppression is largely attributed to cell fate decisions. Here, we provide evidence supporting a novel role for p53 in the regulation of DNA double-strand break (DSB) repair pathway choice. 53BP1, another tumour suppressor, was initially identified as p53 Binding Protein 1, and has been shown to inhibit DNA end resection, thereby stimulating non-homologous end joining (NHEJ). Yet another tumour suppressor, BRCA1, reciprocally promotes end resection and homologous recombination (HR). Here, we show that in both human and mouse cells, the absence of p53 results in impaired 53BP1 focal recruitment to sites of DNA damage induced by ionizing radiation. This effect is largely independent of cell cycle phase and the extent of DNA damage. In p53-deficient cells, diminished localization of 53BP1 is accompanied by a reciprocal increase in BRCA1 recruitment to DSBs. Consistent with these findings, we demonstrate that DSB repair via NHEJ is abrogated, while repair via homology-directed repair (HDR) is stimulated. Overall, we propose that in addition to its role as an ‘effector’ protein in the DNA damage response, p53 plays a role in the regulation of DSB repair pathway choice.

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An unorthodox partnership in DNA repair pathway choice

EMBO Reports ◽

10.15252/embr.201949105 ◽

2019 ◽

Vol 20 (11) ◽

Author(s):

Dimitris Typas ◽

Niels Mailand

Keyword(s):

Dna Repair ◽

Repair Pathway ◽

Pathway Choice

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