scholarly journals Fission Yeast Cut8 Is Required for the Repair of DNA Double-Strand Breaks, Ribosomal DNA Maintenance, and Cell Survival in the Absence of Rqh1 Helicase

2006 ◽  
Vol 27 (5) ◽  
pp. 1558-1567 ◽  
Author(s):  
Stephen E. Kearsey ◽  
Abigail L. Stevenson ◽  
Takashi Toda ◽  
Shao-Win Wang
Keyword(s):  
Homologous Recombination ◽  
Chromosome Segregation ◽  
Strand Break ◽  
Dna Helicase ◽  
Double Strand Breaks ◽  
Proper Function ◽  
Checkpoint Control ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Dna Maintenance

ABSTRACT Schizosaccharomyces pombe Rqh1 is a member of the RecQ DNA helicase family. Members of this protein family are mutated in cancer predisposition diseases, causing Bloom's, Werner, and Rothmund-Thomson syndromes. Rqh1 forms a complex with topoisomerase III and is proposed to process or disrupt aberrant recombination structures that arise during S phase to allow proper chromosome segregation during mitosis. Intriguingly, in the absence of Rqh1, processing of these structures appears to be dependent on Rad3 (human ATR) in a manner that is distinct from its role in checkpoint control. Here, we show that rad3 rqh1 mutants are normally committed to a lethal pathway of DNA repair requiring homologous recombination, but blocking this pathway by Rhp51 inactivation restores viability. Remarkably, viability is also restored by overexpression of Cut8, a nuclear envelope protein involved in tethering and proper function of the proteasome. In keeping with a recently described function of the proteasome in the repair of DNA double-strand breaks, we found that Cut8 is also required for DNA double-strand break repair and is essential for proper chromosome segregation in the absence of Rqh1, suggesting that these proteins might function in a common pathway in homologous recombination repair to ensure accurate nuclear division in S. pombe.

scholarly journals End-resection at DNA double-strand breaks in the three domains of life

2013 ◽  
Vol 41 (1) ◽  
pp. 314-320 ◽  
Author(s):  
John K. Blackwood ◽  
Neil J. Rzechorzek ◽  
Sian M. Bray ◽  
Joseph D. Maman ◽  
Luca Pellegrini ◽  
...  
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
Strand Break ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Homologous Chromosomes ◽  
Domains Of Life ◽  
Strand Invasion ◽  
End Resection

During DNA repair by HR (homologous recombination), the ends of a DNA DSB (double-strand break) must be resected to generate single-stranded tails, which are required for strand invasion and exchange with homologous chromosomes. This 5′–3′ end-resection of the DNA duplex is an essential process, conserved across all three domains of life: the bacteria, eukaryota and archaea. In the present review, we examine the numerous and redundant helicase and nuclease systems that function as the enzymatic analogues for this crucial process in the three major phylogenetic divisions.

Double-strand-break-induced homologous recombination in mammalian cells

2001 ◽  
Vol 29 (2) ◽  
pp. 196-201 ◽  
Author(s):  
R. D. Johnson ◽  
M. Jasin
Keyword(s):  
Homologous Recombination ◽  
Sister Chromatid ◽  
Mammalian Cells ◽  
Indirect Evidence ◽  
Strand Break ◽  
Double Strand Breaks ◽  
Crossing Over ◽  
Dna Double Strand Breaks ◽  
Dsb Repair ◽  
Strand Breaks

In mammalian cells, the repair of DNA double-strand breaks (DSBs) occurs by both homologous and non-homologous mechanisms. Indirect evidence, including that from gene targeting and random integration experiments, had suggested that non-homologous mechanisms were significantly more frequent than homologous ones. However, more recent experiments indicate that homologous recombination is also a prominent DSB repair pathway. These experiments show that mammalian cells use homologous sequences located at multiple positions throughout the genome to repair a DSB. However, template preference appears to be biased, with the sister chromatid being preferred by 2–3 orders of magnitude over a homologous or heterologous chromosome. The outcome of homologous recombination in mammalian cells is predominantly gene conversion that is not associated with crossing-over. The preference for the sister chromatid and the bias against crossing-over seen in mitotic mammalian cells may have developed in order to reduce the potential for genome alterations that could occur when other homologous repair templates are utilized. In attempts to understand further the mechanism of homologous recombination, the proteins that promote this process are beginning to be identified. To date, four mammalian proteins have been demonstrated conclusively to be involved in DSB repair by homologous recombination: Rad54, XRCC2, XRCC3 and BRCAI. This paper summarizes results from a number of recent studies.

scholarly journals UPF1 promotes the formation of R loops to stimulate DNA double-strand break repair

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Greg H. P. Ngo ◽  
Julia W. Grimstead ◽  
Duncan M. Baird
Keyword(s):  
Active Regions ◽  
Strand Break ◽  
Dna Helicase ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Checkpoint Activation ◽  
Strand Breaks ◽  
Dna Double Strand Break ◽  
Dna Resection

AbstractDNA-RNA hybrid structures have been detected at the vicinity of DNA double-strand breaks (DSBs) occurring within transcriptional active regions of the genome. The induction of DNA-RNA hybrids strongly affects the repair of these DSBs, but the nature of these structures and how they are formed remain poorly understood. Here we provide evidence that R loops, three-stranded structures containing DNA-RNA hybrids and the displaced single-stranded DNA (ssDNA) can form at sub-telomeric DSBs. These R loops are generated independently of DNA resection but are induced alongside two-stranded DNA-RNA hybrids that form on ssDNA generated by DNA resection. We further identified UPF1, an RNA/DNA helicase, as a crucial factor that drives the formation of these R loops and DNA-RNA hybrids to stimulate DNA resection, homologous recombination, microhomology-mediated end joining and DNA damage checkpoint activation. Our data show that R loops and DNA-RNA hybrids are actively generated at DSBs to facilitate DNA repair.

scholarly journals FIGL1 and its novel partner FLIP form a conserved complex that regulates homologous recombination

2017 ◽  
Author(s):  
Joiselle Blanche Fernandes ◽  
Marine Duhamel ◽  
Mathilde Séguéla-Arnaud ◽  
Nicole Froger ◽  
Chloé Girard ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Chromosome Segregation ◽  
Double Strand Breaks ◽  
Genetic Screens ◽  
Dna Double Strand Breaks ◽  
Interacting Protein ◽  
Strand Breaks ◽  
Protein Protein Interaction ◽  
Meiotic Crossover ◽  
Strand Invasion

AbstractHomologous recombination is central to repair DNA double-strand breaks (DSB), either accidently arising in mitotic cells or in a programed manner at meiosis. Crossovers resulting from the repair of meiotic breaks are essential for proper chromosome segregation and increase genetic diversity of the progeny. However, mechanisms regulating CO formation remain elusive. Here, we identified through protein-protein interaction and genetic screens FIDGETIN-LIKE-1 INTERACTING PROTEIN (FLIP) as a new partner of the previously characterized anti-crossover factor FIDGETIN-LIKE-1 (FIGL1) in Arabidopsis thaliana. We showed that FLIP limits meiotic crossover together with FIGL1. Further, FLIP and FIGL1 form a protein complex conserved from Arabidopsis to Human. FIGL1 interacts with the recombinases RAD51 and DMC1, the enzymes that catalyze the DNA stand exchange step of homologous recombination. Arabidopsis flip mutants recapitulates the figl1 phenotype, with enhanced meiotic recombination associated with change in DMC1 dynamics. Our data thus suggest that FLIP and FIGL1 form a conserved complex that regulates the crucial step of strand invasion in homologous recombination.

scholarly journals Resection is responsible for loss of transcription around a double-strand break in Saccharomyces cerevisiae

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Nicola Manfrini ◽  
Michela Clerici ◽  
Maxime Wery ◽  
Chiara Vittoria Colombo ◽  
Marc Descrimes ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Homologous Recombination ◽  
Transcriptional Silencing ◽  
Strand Break ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Dsb Repair ◽  
Strand Breaks ◽  
Transcriptional Inhibition ◽  
In Cis

Emerging evidence indicate that the mammalian checkpoint kinase ATM induces transcriptional silencing in cis to DNA double-strand breaks (DSBs) through a poorly understood mechanism. Here we show that in Saccharomyces cerevisiae a single DSB causes transcriptional inhibition of proximal genes independently of Tel1/ATM and Mec1/ATR. Since the DSB ends undergo nucleolytic degradation (resection) of their 5′-ending strands, we investigated the contribution of resection in this DSB-induced transcriptional inhibition. We discovered that resection-defective mutants fail to stop transcription around a DSB, and the extent of this failure correlates with the severity of the resection defect. Furthermore, Rad9 and generation of γH2A reduce this DSB-induced transcriptional inhibition by counteracting DSB resection. Therefore, the conversion of the DSB ends from double-stranded to single-stranded DNA, which is necessary to initiate DSB repair by homologous recombination, is responsible for loss of transcription around a DSB in S. cerevisiae.

Initiation of meiotic recombination by formation of DNA double-strand breaks: mechanism and regulation

2006 ◽  
Vol 34 (4) ◽  
pp. 523-525 ◽  
Author(s):  
S. Keeney ◽  
M.J. Neale
Keyword(s):  
Homologous Recombination ◽  
Protein Kinases ◽  
Chromosome Segregation ◽  
Protein Interactions ◽  
Meiotic Recombination ◽  
Double Strand Breaks ◽  
Protein Protein Interactions ◽  
Dna Double Strand Breaks ◽  
Early Step ◽  
Strand Breaks

Homologous recombination is essential for accurate chromosome segregation during meiosis in most sexual organisms. Meiotic recombination is initiated by the formation of DSBs (DNA double-strand breaks) made by the Spo11 protein. We review here recent findings pertaining to protein–protein interactions important for DSB formation, the mechanism of an early step in the processing of Spo11-generated DSBs, and regulation of DSB formation by protein kinases.

Homologous recombination and the repair of double-strand breaks during cotransformation of Dictyostelium discoideum

1988 ◽  
Vol 8 (7) ◽  
pp. 2779-2786
Author(s):  
K S Katz ◽  
D I Ratner
Keyword(s):  
Homologous Recombination ◽  
Dictyostelium Discoideum ◽  
Strand Break ◽  
Double Strand Breaks ◽  
Restriction Endonucleases ◽  
Linear Molecule ◽  
Strand Breaks ◽  
Transformation Vector ◽  
Closed Circle ◽  
Primary Vector

We examined the ability of unlinked nonreplicating plasmid molecules to undergo homologous recombination during cotransformation of Dictyostelium amoebae. The transformation vector B10S confers resistance to the antibiotic G418 and was always presented to amoebae as a closed circle. Cotransforming DNA, containing a slime mold cDNA and sequences homologous to the primary vector, was presented either as a closed circle or as a linear molecule after digestion with restriction endonucleases which cut within one of three distinct regions of the plasmid. Remarkably, homologous recombination occurred in every clone examined. Moreover, the products of recombination were identical in all instances, irrespective of the presence or position of linearized ends. The ends of the linear templates were not recombinogenic. Repair of the introduced double-strand break occurred frequently during recombination. The repair could occur intermolecularly or, more likely, intramolecularly, i.e., by recircularization. Many of the recombination events were of a nonreciprocal nature. Despite the startlingly frequent level of homologous recombination, the use of cotransforming DNA which contains no homology to the selected vector established that such recombination was not required for cotransformation.

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