scholarly journals Rad9/53BP1 promotes crossover recombination DNA repair by limiting the Sgs1 and Mph1 helicases

2019 ◽  
Author(s):  
Matteo Ferrari ◽  
Chetan C. Rawal ◽  
Samuele Lodovichi ◽  
Achille Pellicioli
Keyword(s):  
Cancer Biology ◽  
Genome Instability ◽  
Strand Break ◽  
Homologous Sequence ◽  
Ssdna Binding ◽  
Downstream Effectors ◽  
Dna Double Strand Break ◽  
Binding Factor ◽  
Different Types ◽  
Break Induced Replication

AbstractA DNA double strand break (DSB) is primed for homologous recombination (HR) repair through the nucleolytic processing (resection) of its ends, leading to the formation of a 3′ single-stranded DNA (ssDNA). Generation of the ssDNA is accompanied by the loading of several repair factors, including the ssDNA binding factor RPA and the recombinase Rad51. Then, depending upon the availability and location of a homologous sequence, different types of HR mechanisms can occur. Inefficient or slow HR repair results in the activation of the DNA damage checkpoint (DDC)1. In budding yeast, the 53BP1 ortholog Rad9 acts as a scaffold, mediating signal from upstream kinases Mec1 and Tel1 (ATR and ATM in human) to downstream effectors kinases Rad53 and Chk1 (CHK2 and CHK1 in human). In addition to its role in DDC, Rad9 limits DSB resection 2. Remarkably, this function is conserved in 53BP1, also being implicated in cancer biology in human cells 3,4.Here we show that Rad9 limits the recruitment of the helicases Sgs1 and Mph1 on to a DSB, promoting Rad51-dependent recombination with long track DNA conversions, crossovers and break-induced replication (BIR). This regulation couples the DDC with the choice and effectiveness of HR sub-pathways, and might be critical to limit genome instability with implication for cancer research.

scholarly journals The balancing act of R-loop biology: The good, the bad, and the ugly

2019 ◽  
Vol 295 (4) ◽  
pp. 905-913 ◽  
Author(s):  
Youssef A. Hegazy ◽  
Chrishan M. Fernando ◽  
Elizabeth J. Tran
Keyword(s):  
Genome Instability ◽  
Strand Break ◽  
Biological Processes ◽  
Physiological Importance ◽  
Future Goals ◽  
Dna Double Strand Break ◽  
Positive Functions ◽  
Acid Structure

An R-loop is a three-stranded nucleic acid structure that consists of a DNA:RNA hybrid and a displaced strand of DNA. R-loops occur frequently in genomes and have significant physiological importance. They play vital roles in regulating gene expression, DNA replication, and DNA and histone modifications. Several studies have uncovered that R-loops contribute to fundamental biological processes in various organisms. Paradoxically, although they do play essential positive functions required for important biological processes, they can also contribute to DNA damage and genome instability. Recent evidence suggests that R-loops are involved in a number of human diseases, including neurological disorders, cancer, and autoimmune diseases. This review focuses on the molecular basis for R-loop–mediated gene regulation and genomic instability and briefly discusses methods for identifying R-loops in vivo. It also highlights recent studies indicating the role of R-loops in DNA double-strand break repair with an updated view of much-needed future goals in R-loop biology.

Histone modifications and DNA double-strand break repair

2004 ◽  
Vol 82 (4) ◽  
pp. 446-452 ◽  
Author(s):  
John D Moore ◽  
Jocelyn E Krebs
Keyword(s):  
Histone Modification ◽  
Histone Modifications ◽  
Strand Break ◽  
Double Strand Break ◽  
Double Strand Break Repair ◽  
Homologous Sequence ◽  
Dna Double Strand Break ◽  
Recombination Repair ◽  
Break Repair ◽  
Gain Access

The roles of different histone modifications have been explored extensively in a number of nuclear processes, particularly in transcriptional regulation. Only recently has the role of histone modification in signaling or facilitating DNA repair begun to be elucidated. DNA broken along both strands in the same region, a double-strand break, is damaged in the most severe way possible and can be the most difficult type of damage to repair accurately. To successfully repair the double-strand break, the cell must gain access to the damaged ends of the DNA and recruit repair factors, and in the case of homologous recombination repair, the cell must also find, colocalize, and gain access to a suitable homologous sequence. In the repair of a double-strand break, the cell must also choose between homologous and non-homologous pathways of repair. Here, we will briefly review the mechanisms of double-strand-break repair, and discuss the known roles of histone modifications in signaling and repairing double-strand breaks.Key words: H23A, double strand break repair, histone modification.

scholarly journals Particles with similar LET values generate DNA breaks of different complexity and reparability: a high-resolution microscopy analysis of γH2AX/53BP1 foci

Nanoscale ◽  
2018 ◽  
Vol 10 (3) ◽  
pp. 1162-1179 ◽  
Author(s):  
Lucie Jezkova ◽  
Mariia Zadneprianetc ◽  
Elena Kulikova ◽  
Elena Smirnova ◽  
Tatiana Bulanova ◽  
...  
Keyword(s):  
Dna Damage ◽  
High Resolution ◽  
Strand Break ◽  
Double Strand Break ◽  
Double Strand Break Repair ◽  
Dna Breaks ◽  
Dna Double Strand Break ◽  
Different Types ◽  
Microscopy Analysis ◽  
High Resolution Microscopy

Different particles with similar LET and energy may generate different types of DNA damage with consequences for DNA double-strand break repair.

scholarly journals Break-Induced Loss of Heterozygosity in Fission Yeast: Dual Roles for Homologous Recombination in Promoting Translocations and Preventing De Novo Telomere Addition

2007 ◽  
Vol 27 (21) ◽  
pp. 7745-7757 ◽  
Author(s):  
Jason K. Cullen ◽  
Sharon P. Hussey ◽  
Carol Walker ◽  
John Prudden ◽  
Boon-Yu Wee ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Loss Of Heterozygosity ◽  
De Novo ◽  
Strand Break ◽  
Dual Roles ◽  
Dna Double Strand Break ◽  
Break Site ◽  
Break Induced Replication ◽  
End Resection ◽  
Causal Event

ABSTRACT Loss of heterozygosity (LOH), a causal event in tumorigenesis, frequently encompasses multiple genetic loci and whole chromosome arms. However, the mechanisms leading to such extensive LOH are poorly understood. We investigated the mechanisms of DNA double-strand break (DSB)-induced extensive LOH by screening for auxotrophic marker loss ∼25 kb distal to an HO endonuclease break site within a nonessential minichromosome in Schizosaccharomyces pombe. Extensive break-induced LOH was infrequent, resulting from large translocations through both allelic crossovers and break-induced replication. These events required the homologous recombination (HR) genes rad32 +, rad50 +, nbs1 +, rhp51 +, rad22 +, rhp55 +, rhp54 +, and mus81 +. Surprisingly, LOH was still observed in HR mutants, which resulted predominantly from de novo telomere addition at the break site. De novo telomere addition was most frequently observed in rad22Δ and rhp55Δ backgrounds, which disrupt HR following end resection. Further, levels of de novo telomere addition, while increased in ku70Δ rhp55Δ strains, were reduced in exo1Δ rhp55Δ and an rhp55Δ strain overexpressing rhp51. These findings support a model in which HR prevents de novo telomere addition at DSBs by competing for resected ends. Together, these results suggest that the mechanisms of break-induced LOH may be predicted from the functional status of the HR machinery.

scholarly journals RIF1 acts in DNA repair through phosphopeptide recognition of 53BP1

2021 ◽  
Author(s):  
Dheva Setiaputra ◽  
Cristina Escribano-Diaz ◽  
Julia K. Reinert ◽  
Pooja Sadana ◽  
Dali Zong ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Binding Sites ◽  
Binding Protein ◽  
Strand Break ◽  
Chromatin Binding ◽  
Alternative Mode ◽  
Downstream Effectors ◽  
Dna Double Strand Break ◽  
Radiation Induced

SummaryThe chromatin-binding protein 53BP1 promotes DNA repair by orchestrating the recruitment of downstream effectors including PTIP, RIF1 and shieldin to DNA double-strand break sites. While how PTIP recognizes 53BP1 is known, the molecular details of RIF1 recruitment to DNA damage sites remains undefined. Here, we report that RIF1 is a phosphopeptide-binding protein that directly interacts with three phosphorylated 53BP1 epitopes. The RIF1-binding sites on 53BP1 share an essential LxL motif followed by two closely apposed phosphorylated residues. Simultaneous mutation of these sites on 53BP1 abrogates RIF1 accumulation into ionizing radiation-induced foci, but surprisingly only fully compromises 53BP1-dependent DNA repair when an alternative mode of shieldin recruitment to DNA damage sites is also disabled. Intriguingly, this alternative mode of recruitment still depends on RIF1 but does not require its interaction with 53BP1. RIF1 therefore employs phosphopeptide recognition to promote DNA repair but also modifies shieldin action independently of 53BP1 binding.

scholarly journals Exploring the Structures and Functions of Macromolecular SLX4-Nuclease Complexes in Genome Stability

2021 ◽  
Vol 12 ◽  
Author(s):  
Brandon J. Payliss ◽  
Ayushi Patel ◽  
Anneka C. Sheppard ◽  
Haley D. M. Wyatt
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
Genome Stability ◽  
Genome Instability ◽  
Strand Break ◽  
Biochemical Properties ◽  
Strand Breaks ◽  
Dna Double Strand Break ◽  
Recent Developments ◽  
And Function

All organisms depend on the ability of cells to accurately duplicate and segregate DNA into progeny. However, DNA is frequently damaged by factors in the environment and from within cells. One of the most dangerous lesions is a DNA double-strand break. Unrepaired breaks are a major driving force for genome instability. Cells contain sophisticated DNA repair networks to counteract the harmful effects of genotoxic agents, thus safeguarding genome integrity. Homologous recombination is a high-fidelity, template-dependent DNA repair pathway essential for the accurate repair of DNA nicks, gaps and double-strand breaks. Accurate homologous recombination depends on the ability of cells to remove branched DNA structures that form during repair, which is achieved through the opposing actions of helicases and structure-selective endonucleases. This review focuses on a structure-selective endonuclease called SLX1-SLX4 and the macromolecular endonuclease complexes that assemble on the SLX4 scaffold. First, we discuss recent developments that illuminate the structure and biochemical properties of this somewhat atypical structure-selective endonuclease. We then summarize the multifaceted roles that are fulfilled by human SLX1-SLX4 and its associated endonucleases in homologous recombination and genome stability. Finally, we discuss recent work on SLX4-binding proteins that may represent integral components of these macromolecular nuclease complexes, emphasizing the structure and function of a protein called SLX4IP.

scholarly journals Different types of V(D)J recombination and end-joining defects in DNA double-strand break repair mutant mammalian cells

2002 ◽  
Vol 32 (3) ◽  
pp. 701 ◽  
Author(s):  
Nicole S. Verkaik ◽  
Rebecca E. E. Esveldt-van Lange ◽  
Diana van Heemst ◽  
Hennie T. Brüggenwirth ◽  
Jan H. J. Hoeijmakers ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Strand Break ◽  
Double Strand Break ◽  
Double Strand Break Repair ◽  
End Joining ◽  
Dna Double Strand Break ◽  
Different Types ◽  
Break Repair

Effect of BRCA1 missense variants on gene reversion in DNA double-strand break repair mutants and cell cycle-arrested cells of Saccharomyces cerevisiae

Mutagenesis ◽  
2019 ◽  
Vol 35 (2) ◽  
pp. 189-195 ◽  
Author(s):  
Samuele Lodovichi ◽  
Francesca Bellè ◽  
Tiziana Cervelli ◽  
Alessandra Lorenzoni ◽  
Luisa Maresca ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Repair ◽  
Genome Instability ◽  
Strand Break ◽  
S Phase ◽  
Base Substitution ◽  
Missense Variants ◽  
Pathogenic Variants ◽  
Dna Double Strand Break ◽  
High Level

Abstract Evaluation of the functional impact of germline BRCA1 variants that are likely to be associated to breast and ovarian cancer could help to investigate the mechanism of BRCA1 tumorigenesis. Expression of pathogenic BRCA1 missense variants increased homologous recombination (HR) and gene reversion (GR) in yeast. We thought to exploit yeast genetics to shed light on BRCA1-induced genome instability and tumorigenesis. We determined the effect on GR of several neutral and pathogenic BRCA1 variants in the yeast strain RSY6wt and its isogenic DSB repair mutants, such as mre11∆, rad50∆ and rad51∆. In the RSY6wt, four out of five pathogenic and two out of six neutral variants significantly increased GR; rad51∆ strain, the pathogenic variants C61G and A1708E induced a weak but significant increase in GR. On the other hand, in rad50∆ mutant expressing the pathogenic variants localised at the BRCT domain, a further GR increase was seen. The neutral variant N132K and the VUS A1789T induced a weak GR increase in mre11∆ mutant. Thus, BRCA1 missense variants require specific genetic functions and presumably induced GR by different mechanisms. As DNA repair is regulated by cell cycle, we determined the effect on GR of BRCA1 variants in cell cycle-arrested RSYwt cells. GR is highly BRCA1-inducible in S-phase-arrested cells as compared to G1 or G2. Sequence analysis of genomic DNA from ILV1 revertant clones showed that BRCA1-induced ilv1-92 reversion by base substitution when GR is at least 6-fold over the control. Our study demonstrated that BRCA1 may interfere with yeast DNA repair functions that are active in S-phase causing high level of GR. In addition, we confirmed here that yeast could be a reliable model to investigate the mechanism and genetic requirements of BRCA1-induced genome instability. Finally, developing yeast-based assays to characterise BRCA1 missense variants could be useful to design more precise therapies.

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