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

2019 ◽  
Vol 47 (20) ◽  
pp. 10678-10692 ◽  
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.

scholarly journals SCFSKP2 regulates APC/CCDH1-mediated degradation of CTIP to adjust DNA-end resection in G2-phase

2020 ◽  
Vol 11 (7) ◽  
Author(s):  
Fanghua Li ◽  
Emil Mladenov ◽  
Sharif Mortoga ◽  
George Iliakis
Keyword(s):  
Cell Cycle ◽  
Cell Survival ◽  
S Phase ◽  
Repair Pathway ◽  
End Joining ◽  
Alternative End Joining ◽  
G2 Phase ◽  
Dna End Resection ◽  
Cycle Dependent ◽  
End Resection

Abstract The cell cycle-dependent engagement of DNA-end resection at DSBs is regulated by phosphorylation of CTIP by CDKs, the central regulators of cell cycle transitions. Cell cycle transitions are also intimately regulated by protein degradation via two E3 ubiquitin ligases: SCFSKP2 and APC/CCDH1 complex. Although APC/CCDH1 regulates CTIP in G1– and G2-phase, contributions by SCFSKP2 have not been reported. We demonstrate that SCFSKP2 is a strong positive regulator of resection. Knockdown of SKP2, fully suppresses resection in several cell lines. Notably, this suppression is G2-phase specific and is not observed in S-phase or G1–phase cells. Knockdown of SKP2 inactivates SCFSKP2 causing APC/CCDH1 activation, which degrades CTIP. The stabilizing function of SCFSKP2 on CTIP promotes resection and supports gene conversion (GC), alternative end joining (alt-EJ) and cell survival. We propose that CDKs and SCFSKP2-APC/CCDH1 cooperate to regulate resection and repair pathway choice at DSBs in G2-phase.

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

Open Biology ◽  
2016 ◽  
Vol 6 (9) ◽  
pp. 160225 ◽  
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.

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

2015 ◽  
Vol 17 (11) ◽  
pp. 1446-1457 ◽  
Author(s):  
Ismail Hassan Ismail ◽  
Jean-Philippe Gagné ◽  
Marie-Michelle Genois ◽  
Hilmar Strickfaden ◽  
Darin McDonald ◽  
...  
Keyword(s):  
Dna Repair ◽  
E3 Ligase ◽  
Repair Pathway ◽  
Pathway Choice ◽  
Dna End Resection ◽  
End Resection

scholarly journals Phosphorylation of EXO1 by CDKs 1 and 2 regulates DNA end resection and repair pathway choice

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Nozomi Tomimatsu ◽  
Bipasha Mukherjee ◽  
Molly Catherine Hardebeck ◽  
Mariya Ilcheva ◽  
Cristel Vanessa Camacho ◽  
...  
Keyword(s):  
Repair Pathway ◽  
Pathway Choice ◽  
Dna End Resection ◽  
End Resection

scholarly journals Phosphorylation of Ku dictates DNA double-strand break (DSB) repair pathway choice in S phase

2015 ◽  
Vol 44 (4) ◽  
pp. 1732-1745 ◽  
Author(s):  
Kyung-Jong Lee ◽  
Janapriya Saha ◽  
Jingxin Sun ◽  
Kazi R. Fattah ◽  
Shu-Chi Wang ◽  
...  
Keyword(s):  
Strand Break ◽  
Double Strand Break ◽  
S Phase ◽  
Repair Pathway ◽  
Dsb Repair ◽  
Dna Double Strand Break ◽  
Pathway Choice

scholarly journals RB Regulates DNA Double Strand Break Repair Pathway Choice by Mediating CtIP Dependent End Resection

2020 ◽  
Vol 21 (23) ◽  
pp. 9176
Author(s):  
Yuning Jiang ◽  
Jason C. Yam ◽  
Clement C. Tham ◽  
Chi Pui Pang ◽  
Wai Kit Chu
Keyword(s):  
Genome Instability ◽  
Synthetic Lethality ◽  
Strand Break ◽  
Suppressor Gene ◽  
Repair Pathway ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Dsb Repair ◽  
Pathway Choice ◽  
End Resection

Inactivation of the retinoblastoma tumor suppressor gene (RB1) leads to genome instability, and can be detected in retinoblastoma and other cancers. One damaging effect is causing DNA double strand breaks (DSB), which, however, can be repaired by homologous recombination (HR), classical non-homologous end joining (C-NHEJ), and micro-homology mediated end joining (MMEJ). We aimed to study the mechanistic roles of RB in regulating multiple DSB repair pathways. Here we show that HR and C-NHEJ are decreased, but MMEJ is elevated in RB-depleted cells. After inducing DSB by camptothecin, RB co-localizes with CtIP, which regulates DSB end resection. RB depletion leads to less RPA and native BrdU foci, which implies less end resection. In RB-depleted cells, less CtIP foci, and a lack of phosphorylation on CtIP Thr847, are observed. According to the synthetic lethality principle, based on the altered DSB repair pathway choice, after inducing DSBs by camptothecin, RB depleted cells are more sensitive to co-treatment with camptothecin and MMEJ blocker poly-ADP ribose polymerase 1 (PARP1) inhibitor. We propose a model whereby RB can regulate DSB repair pathway choice by mediating the CtIP dependent DNA end resection. The use of PARP1 inhibitor could potentially improve treatment outcomes for RB-deficient cancers.

scholarly journals MSH2-MSH3 promotes DNA end resection during HR and blocks TMEJ through interaction with SMARCAD1 and EXO1

2021 ◽  
Author(s):  
Jung-Min Oh ◽  
Yujin Kang ◽  
Jumi Park ◽  
Yubin Sung ◽  
Dayoung Kim ◽  
...  
Keyword(s):  
Strand Break ◽  
Repair Pathway ◽  
End Joining ◽  
Dsb Repair ◽  
Direct Role ◽  
Dna Double Strand Break ◽  
Dna End Resection ◽  
Template Dna ◽  
End Resection

SUMMARYDNA double strand break (DSB) repair by Homologous recombination (HR) is initiated by the end resection, a process during which 3’ ssDNA overhangs are generated by the nucleolytic degradation. The extent of DNA end resection determines the choice of the DSB repair pathway. The role of several proteins including nucleases for end resection has been studied in detail. However, it is still unclear how the initial, nicked DNA generated by MRE11-RAD50-NBS1 is recognized and how subsequent proteins including EXO1 are recruited to DSB sites to facilitate extensive end resection. We found that the MutSβ (MSH2-MSH3) mismatch repair (MMR) complex is recruited to DSB sites by recognizing the initial nicked DNA at DSB sites through the interaction with the chromatin remodeling protein SMARCAD1. MSH2-MSH3 at DSB sites helps to recruit EXO1 for long-range resection and enhances its enzymatic activity. MSH2-MSH3 furthermore inhibits the access of DNA polymerase θ (POLQ), which promotes polymerase theta-mediated end-joining (TMEJ) of DSB. Collectively, our data show a direct role for MSH2-MSH3 in the initial stages of DSB repair by promoting end resection and influencing DSB repair pathway by favoring HR over TMEJ. Our findings extend the importance of MMR in DSB repair beyond established role in rejecting the invasion of sequences not perfectly homologous to template DNA during late-stage HR.

Repair pathway choice for double-strand breaks

2020 ◽  
Vol 64 (5) ◽  
pp. 765-777 ◽  
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.

scholarly journals Human SIRT6 Promotes DNA End Resection Through CtIP Deacetylation

Science ◽  
2010 ◽  
Vol 329 (5997) ◽  
pp. 1348-1353 ◽  
Author(s):  
Abderrahmane Kaidi ◽  
Brian T. Weinert ◽  
Chunaram Choudhary ◽  
Stephen P. Jackson
Keyword(s):  
Homologous Recombination ◽  
Genome Stability ◽  
Protein A ◽  
Strand Break ◽  
Dsb Repair ◽  
Interacting Protein ◽  
Dna Double Strand Break ◽  
Dna End Resection ◽  
Lysine Deacetylases ◽  
End Resection

SIRT6 belongs to the sirtuin family of protein lysine deacetylases, which regulate aging and genome stability. We found that human SIRT6 has a role in promoting DNA end resection, a crucial step in DNA double-strand break (DSB) repair by homologous recombination. SIRT6 depletion impaired the accumulation of replication protein A and single-stranded DNA at DNA damage sites, reduced rates of homologous recombination, and sensitized cells to DSB-inducing agents. We identified the DSB resection protein CtIP [C-terminal binding protein (CtBP) interacting protein] as a SIRT6 interaction partner and showed that SIRT6-dependent CtIP deacetylation promotes resection. A nonacetylatable CtIP mutant alleviated the effect of SIRT6 depletion on resection, thus identifying CtIP as a key substrate by which SIRT6 facilitates DSB processing and homologous recombination. These findings further clarify how SIRT6 promotes genome stability.

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