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.

scholarly journals RAD6 Promotes Homologous Recombination Repair by Activating the Autophagy-Mediated Degradation of Heterochromatin Protein HP1

2014 ◽  
Vol 35 (2) ◽  
pp. 406-416 ◽  
Author(s):  
Su Chen ◽  
Chen Wang ◽  
Luxi Sun ◽  
Da-Liang Wang ◽  
Lu Chen ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Genome Stability ◽  
Chromosomal Rearrangements ◽  
Strand Break ◽  
Open Chromatin ◽  
Dsb Repair ◽  
Heterochromatin Protein ◽  
Dna Double Strand Break ◽  
Recombination Repair ◽  
Ubiquitin Conjugating Enzyme

Efficient DNA double-strand break (DSB) repair is critical for the maintenance of genome stability. Unrepaired or misrepaired DSBs cause chromosomal rearrangements that can result in severe consequences, such as tumorigenesis. RAD6 is an E2 ubiquitin-conjugating enzyme that plays a pivotal role in repairing UV-induced DNA damage. Here, we present evidence that RAD6 is also required for DNA DSB repair via homologous recombination (HR) by specifically regulating the degradation of heterochromatin protein 1α (HP1α). Our study indicates that RAD6 physically interacts with HP1α and ubiquitinates HP1α at residue K154, thereby promoting HP1α degradation through the autophagy pathway and eventually leading to an open chromatin structure that facilitates efficient HR DSB repair. Furthermore, bioinformatics studies have indicated that the expression of RAD6 and HP1α exhibits an inverse relationship and correlates with the survival rate of patients.

scholarly journals Nucleosome disassembly during human non-homologous end joining followed by concerted HIRA- and CAF-1-dependent reassembly

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Xuan Li ◽  
Jessica K Tyler
Keyword(s):  
Strand Break ◽  
End Joining ◽  
Efficient Removal ◽  
Dsb Repair ◽  
Dna Double Strand Break ◽  
Dna End Resection ◽  
Non Homologous End Joining ◽  
Nucleosome Disassembly ◽  
End Resection ◽  
Assembly Pathways

The cell achieves DNA double-strand break (DSB) repair in the context of chromatin structure. However, the mechanisms used to expose DSBs to the repair machinery and to restore the chromatin organization after repair remain elusive. Here we show that induction of a DSB in human cells causes local nucleosome disassembly, apparently independently from DNA end resection. This efficient removal of histone H3 from the genome during non-homologous end joining was promoted by both ATM and the ATP-dependent nucleosome remodeler INO80. Chromatin reassembly during DSB repair was dependent on the HIRA histone chaperone that is specific to the replication-independent histone variant H3.3 and on CAF-1 that is specific to the replication-dependent canonical histones H3.1/H3.2. Our data suggest that the epigenetic information is re-established after DSB repair by the concerted and interdependent action of replication-independent and replication-dependent chromatin assembly pathways.

The human HELLS chromatin remodelling protein promotes end resection to facilitate homologous recombination within heterochromatin

2018 ◽  
Author(s):  
G. Kollarovic ◽  
C. E. Topping ◽  
E. P. Shaw ◽  
A. L. Chambers
Keyword(s):  
Homologous Recombination ◽  
Cancer Biology ◽  
Genome Stability ◽  
Strand Break ◽  
Chromatin Remodelling ◽  
Dsb Repair ◽  
Icf Syndrome ◽  
Damage Response ◽  
Break Repair ◽  
End Resection

ABSTRACTEfficient double-strand break repair in eukaryotes requires manipulation of chromatin structure. ATP-dependent chromatin remodelling enzymes can facilitate different DNA repair pathways, during different stages of the cell cycle and in a range of chromatin environments. The contribution of remodelling factors to break repair within heterochromatin during G2 is unclear.The human HELLS protein is a Snf2-like chromatin remodeller family member and is mutated or misregulated in several cancers and some cases of ICF syndrome. HELLS has been implicated in the DNA damage response, but its mechanistic function in repair is not well understood. We find that HELLS facilitates homologous recombination at two-ended breaks within heterochromatic regions during G2. HELLS enables end-resection and accumulation of CtIP at IR-induced foci. We identify an interaction between HELLS and CtIP and establish that the ATPase domain of HELLS is required to promote DSB repair. This function of HELLS in maintenance of genome stability is likely to contribute to its role in cancer biology and demonstrates that different chromatin remodelling activities are required for efficient repair in specific genomic contexts.

scholarly journals Competing interactions modulate the activity of Sgs1 during DNA end resection

2019 ◽  
Author(s):  
Kristina Kasaciunaite ◽  
Fergus Fettes ◽  
Maryna Levikova ◽  
Peter Daldrop ◽  
Petr Cejka ◽  
...  
Keyword(s):  
Single Molecule ◽  
Genome Stability ◽  
Strand Break ◽  
Cellular Functions ◽  
Single Stranded Dna ◽  
Single Molecule Level ◽  
Protein Partners ◽  
Dna Double Strand Break ◽  
Dna End Resection ◽  
End Resection

AbstractDNA double-strand break repair by homologous recombination employs long-range resection of the 5’ DNA ends at the break points. In Saccharomyces cerevisiae, this process can be performed by the RecQ helicase Sgs1 and the helicase-nuclease Dna2. Though functional interplay has been shown, it remains unclear whether and how the proteins cooperate on the molecular level. Here, we resolved the dynamics of DNA unwinding by Sgs1 at the single molecule level and investigated its regulation by Dna2, the single-stranded DNA binding protein RPA and the Top3-Rmi1 complex. We found that Dna2 modulates the velocity of Sgs1, indicating that during end resection the proteins form a physical complex and couple their activities. Sgs1 unwinds DNA and feeds single-stranded DNA to Dna2 for degradation. RPA is found to regulate the processivity and the affinity of Sgs1 to the DNA fork, while Top3-Rmi1 modulated the velocity of Sgs1. We think that the differential regulation of the Sgs1 activity by its protein partners is important to allow diverse cellular functions of Sgs1 during the maintenance of genome stability.

scholarly journals End resection: a key step in homologous recombination and DNA double-strand break repair

2020 ◽  
Author(s):  
Sijie Liu ◽  
Daochun Kong
Keyword(s):  
Homologous Recombination ◽  
Strand Break ◽  
Double Strand Break ◽  
General Process ◽  
Dna Double Strand Break ◽  
Biochemical Mechanisms ◽  
Strand Invasion ◽  
Dna End Resection ◽  
End Resection ◽  
Made In

AbstractDNA end resection in eukaryotes is a key step in DNA homologous recombination (HR) and HR-mediated DNA double-strand break (DSB) repair, in which DNA2, EXO1 and MRE11 endo- and exonucleases remove several kilobases from the 5′ terminus of the DNA with DSB, while the 3′ terminus remains intact. The end resection-generated 3′ single-stranded DNA (ssDNA) overhang is then coated by RAD51 for subsequent strand invasion. In the last two decades, great progress has been made in understanding the biochemical mechanisms of end resection, including the identification of various enzymes involved in this process. However, some important questions about this process remain to be resolved. In this review, we summarize the general process of end resection and discuss the implications of the most recent findings for understanding of the end resection machinery.

scholarly journals LIN37-DREAM prevents DNA end resection and homologous recombination at DNA double-strand breaks in quiescent cells

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Bo-Ruei Chen ◽  
Yinan Wang ◽  
Anthony Tubbs ◽  
Dali Zong ◽  
Faith C Fowler ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Strand Break ◽  
Dna Double Strand Breaks ◽  
Independent Manner ◽  
Strand Breaks ◽  
Quiescent Cells ◽  
Dna Double Strand Break ◽  
Dna End Resection ◽  
Brca1 Brca2 ◽  
End Resection

DNA double-strand break (DSB) repair by homologous recombination (HR) is thought to be restricted to the S- and G2- phases of the cell cycle in part due to 53BP1 antagonizing DNA end resection in G1-phase and non-cycling quiescent (G0) cells. Here, we show that LIN37, a component of the DREAM transcriptional repressor, functions in a 53BP1-independent manner to prevent DNA end resection and HR in G0 cells. Loss of LIN37 leads to the expression of HR proteins, including BRCA1, BRCA2, PALB2, and RAD51, and promotes DNA end resection in G0 cells even in the presence of 53BP1. In contrast to 53BP1-deficiency, DNA end resection in LIN37-deficient G0 cells depends on BRCA1 and leads to RAD51 filament formation and HR. LIN37 is not required to protect DNA ends in cycling cells at G1-phase. Thus, LIN37 regulates a novel 53BP1-independent cell phase-specific DNA end protection pathway that functions uniquely in quiescent cells.

scholarly journals NBS1-CtIP–Mediated DNA End Resection Regulates cGAS Binding to Micronuclei

2020 ◽  
Author(s):  
Salim Abdisalaam ◽  
Shibani Mukherjee ◽  
Souparno Bhattacharya ◽  
Debapriya Sinha ◽  
Sharda Kumari ◽  
...  
Keyword(s):  
Critical Role ◽  
Protein A ◽  
Nijmegen Breakage Syndrome ◽  
Strand Break ◽  
Direct Role ◽  
Interacting Protein ◽  
Dna End Resection ◽  
End Resection ◽  
Dna Ends

AbstractCyclic GMP-AMP synthase (cGAS), an important component of immune signaling, is hyperactivated in cells defective for DNA damage response (DDR) signaling. However, a direct role for DDR factors in the regulation of cGAS functions is mostly unknown. Here, we provide novel evidence that Nijmegen breakage syndrome 1 (NBS1) protein, a well-studied DNA double-strand break (DSB) sensor, in coordination with ATM, a protein kinase, and CtBP-interacting protein (CtIP), a DNA end resection factor, functions as an upstream regulator of cGAS binding to micronuclei. Upon NBS1 binding to micronuclei via its fork-head–associated domain, it recruits ATM and CtIP via its N- and C-terminal domains, respectively. Subsequently, ATM stabilizes NBS1’s interaction with micronuclei, and CtIP converts DSB ends into single-strand DNA ends, and these two key events preclude cGAS from binding to micronuclei. Notably, we show that purified cGAS cannot form a complex with DNA substrates that mimic resected DNA ends in vitro. Thus, NBS1 together with its binding partners modify the chromatin architecture of the micronuclei and that plays a critical role in cGAS’s binding to micronuclei.

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.

scholarly journals MicroRNAs down-regulate homologous recombination in the G1 phase of cycling cells to maintain genomic stability

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Young Eun Choi ◽  
Yunfeng Pan ◽  
Eunmi Park ◽  
Panagiotis Konstantinopoulos ◽  
Subhajyoti De ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Strand Break ◽  
G1 Phase ◽  
End Joining ◽  
Dsb Repair ◽  
Dna Double Strand Break ◽  
Dna End Resection ◽  
Non Homologous End Joining ◽  
Brca1 Brca2 ◽  
G1 Cells

Homologous recombination (HR)-mediated repair of DNA double-strand break (DSB)s is restricted to the post-replicative phases of the cell cycle. Initiation of HR in the G1 phase blocks non-homologous end joining (NHEJ) impairing DSB repair. Completion of HR in G1 cells can lead to the loss-of-heterozygosity (LOH), which is potentially carcinogenic. We conducted a gain-of-function screen to identify miRNAs that regulate HR-mediated DSB repair, and of these miRNAs, miR-1255b, miR-148b*, and miR-193b* specifically suppress the HR-pathway in the G1 phase. These miRNAs target the transcripts of HR factors, BRCA1, BRCA2, and RAD51, and inhibiting miR-1255b, miR-148b*, and miR-193b* increases expression of BRCA1/BRCA2/RAD51 specifically in the G1-phase leading to impaired DSB repair. Depletion of CtIP, a BRCA1-associated DNA end resection protein, rescues this phenotype. Furthermore, deletion of miR-1255b, miR-148b*, and miR-193b* in independent cohorts of ovarian tumors correlates with significant increase in LOH events/chromosomal aberrations and BRCA1 expression.

scholarly journals The human HELLS chromatin remodelling protein promotes end resection to facilitate homologous recombination and contributes to DSB repair within heterochromatin

2019 ◽  
Vol 48 (4) ◽  
pp. 1872-1885 ◽  
Author(s):  
Gabriel Kollárovič ◽  
Caitríona E Topping ◽  
Edward P Shaw ◽  
Anna L Chambers
Keyword(s):  
Homologous Recombination ◽  
Cancer Biology ◽  
Genome Stability ◽  
Strand Break ◽  
Double Strand Break ◽  
Chromatin Remodelling ◽  
Double Strand Break Repair ◽  
Dsb Repair ◽  
Break Repair ◽  
End Resection

Abstract Efficient double-strand break repair in eukaryotes requires manipulation of chromatin structure. ATP-dependent chromatin remodelling enzymes facilitate different DNA repair pathways, during different stages of the cell cycle and in varied chromatin environments. The contribution of remodelling factors to double-strand break repair within heterochromatin during G2 is unclear. The human HELLS protein is a Snf2-like chromatin remodeller family member and is mutated or misregulated in several cancers and some cases of ICF syndrome. HELLS has been implicated in the DNA damage response, but its mechanistic function in repair is not well understood. We discover that HELLS facilitates homologous recombination at two-ended breaks and contributes to repair within heterochromatic regions during G2. HELLS promotes initiation of HR by facilitating end-resection and accumulation of CtIP at IR-induced foci. We identify an interaction between HELLS and CtIP and establish that the ATPase domain of HELLS is required to promote DSB repair. This function of HELLS in maintenance of genome stability is likely to contribute to its role in cancer biology and demonstrates that different chromatin remodelling activities are required for efficient repair in specific genomic contexts.

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