Double–strand breaks on YACs during yeast meiosis may reflect meiotic recombination in the human genome

1996 ◽  
Vol 13 (4) ◽  
pp. 481-484 ◽  
Author(s):  
Shoshana Klein ◽  
Drora Zenvirth ◽  
Amir Sherman ◽  
Karin Ried ◽  
Gudrun Rappold ◽  
...  
2017 ◽  
Author(s):  
Charles J. Underwood ◽  
Kyuha Choi ◽  
Christophe Lambing ◽  
Xiaohui Zhao ◽  
Heïdi Serra ◽  
...  

AbstractEukaryotic centromeres contain the kinetochore, which connects chromosomes to the spindle allowing segregation. During meiosis centromeres are suppressed for crossovers, as recombination in these regions can cause chromosome mis-segregation. Plant centromeres are surrounded by repetitive, transposon-dense heterochromatin that is epigenetically silenced by histone 3 lysine 9 dimethylation (H3K9me2), and DNA methylation in CG and non-CG sequence contexts. Here we show that disruption of Arabidopsis H3K9me2 and non-CG DNA methylation pathways increases meiotic DNA double strand breaks (DSBs) within centromeres, whereas crossovers increase within pericentromeric heterochromatin. Increased pericentromeric crossovers in H3K9me2/non-CG mutants occurs in both inbred and hybrid backgrounds, and involves the interfering crossover repair pathway. Epigenetic activation of recombination may also account for the curious tendency of maize transposon Ds to disrupt CHROMOMETHYLASE3 when launched from proximal loci. Thus H3K9me2 and non-CG DNA methylation exert differential control of meiotic DSB and crossover formation in centromeric and pericentromeric heterochromatin.


2016 ◽  
Author(s):  
Neeman Mohibullah ◽  
Scott Keeney

AbstractThe Spo11-generated double-strand breaks (DSBs) that initiate meiotic recombination are dangerous lesions that can disrupt genome integrity, so meiotic cells regulate their number, timing, and distribution. Here, we use Spo11-oligonucleotide complexes, a byproduct of DSB formation, to examine the contribution of the DNA damage-responsive kinase Tel1 (ortholog of mammalian ATM) to this regulation in Saccharomyces cerevisiae. A tel1Δ mutant had globally increased amounts of Spo11-oligonucleotide complexes and altered Spo11-oligonucleotide lengths, consistent with conserved roles for Tel1 in control of DSB number and processing. A kinase-dead tell mutation also increased Spo11-oligonucleotide levels, but mutating known Tel1 phosphotargets on Hop1 and Rec114 did not. Deep sequencing of Spo11 oligonucleotides from tel1Δ mutants demonstrated that Tel1 shapes the nonrandom DSB distribution in ways that are distinct but partially overlapping with previously described contributions of the recombination regulator Zip3. Finally, we uncover a context-dependent role for Tel1 in hotspot competition, in which an artificial DSB hotspot inhibits nearby hotspots. Evidence for Tel1-dependent competition involving strong natural hotspots is also provided.


2007 ◽  
Vol 36 (3) ◽  
pp. 984-997 ◽  
Author(s):  
Tomoyuki Fukuda ◽  
Kazuto Kugou ◽  
Hiroyuki Sasanuma ◽  
Takehiko Shibata ◽  
Kunihiro Ohta

Science ◽  
2017 ◽  
Vol 355 (6320) ◽  
pp. 40-45 ◽  
Author(s):  
Eleni P. Mimitou ◽  
Shintaro Yamada ◽  
Scott Keeney

DNA double-strand breaks that initiate meiotic recombination are exonucleolytically processed. This 5′→3′ resection is a central, conserved feature of recombination but remains poorly understood. To address this lack, we mapped resection endpoints genome-wide at high resolution inSaccharomyces cerevisiae. Full-length resection requires Exo1 exonuclease and the DSB-responsive kinase Tel1, but not Sgs1 helicase. Tel1 also promotes efficient and timely resection initiation. Resection endpoints display pronounced heterogeneity between genomic loci that reflects a tendency for nucleosomes to block Exo1, yet Exo1 also appears to digest chromatin with high processivity and at rates similar to naked DNA in vitro. This paradox points to nucleosome destabilization or eviction as a defining feature of the meiotic resection landscape.


2006 ◽  
Vol 26 (10) ◽  
pp. 3683-3694 ◽  
Author(s):  
Hsin-Yen Wu ◽  
Sean M. Burgess

ABSTRACT Dynamic telomere repositioning is a prominent feature of meiosis. Deletion of a telomere-associated protein, Ndj1, results in the failure of both attachment and clustering of telomeres at the nuclear envelope and delays several landmarks of meiosis I, such as pairing, synaptonemal complex formation, and timing of the meiosis I division. We explored the role of Ndj1 in meiotic recombination, which occurs through the formation and repair of programmed double-strand breaks. The ndj1Δ mutation allows for the formation of the first detectable strand invasion intermediate (i.e., single-end invasion) with wild-type kinetics; however, it confers a delay in the formation of the double-Holliday junction intermediate and both crossover and noncrossover products. These results challenge the widely held notion that clustering of telomeres in meiosis promotes the ability of homologous chromosomes to find one another in budding Saccharomyces cerevisiae. We propose that an Ndj1-dependent function is critical for stabilizing analogous strand invasion intermediates that exist in two separate branches of the bifurcated pathway, leading to either noncrossover or crossover formation. These findings provide a link between telomere dynamics and a distinct mechanistic step of meiotic recombination that follows the homology search.


2004 ◽  
Vol 24 (11) ◽  
pp. 5016-5027 ◽  
Author(s):  
Chantal Wicky ◽  
Arno Alpi ◽  
Myriam Passannante ◽  
Ann Rose ◽  
Anton Gartner ◽  
...  

ABSTRACT Bloom's syndrome (BS) is an autosomal-recessive human disorder caused by mutations in the BS RecQ helicase and is associated with loss of genomic integrity and an increased incidence of cancer. We analyzed the mitotic and the meiotic roles of Caenorhabditis elegans him-6, which we show to encode the ortholog of the human BS gene. Mutations in him-6 result in an enhanced irradiation sensitivity, a partially defective S-phase checkpoint, and in reduced levels of DNA-damage induced apoptosis. Furthermore, him-6 mutants exhibit a decreased frequency of meiotic recombination that is probably due to a defect in the progression of crossover recombination. In mitotically proliferating germ cells, our genetic interaction studies, as well as the assessment of the number of double-strand breaks via RAD-51 foci, reveal a complex regulatory network that is different from the situation in yeast. Although the number of double-strand breaks in him-6 and top-3 single mutants is elevated, the combined depletion of him-6 and top-3 leads to mitotic catastrophe concomitant with a massive increase in the level of double-strand breaks, a phenotype that is completely suppressed by rad-51. him-6 and top-3 are thus needed to maintain low levels of double-strand breaks in normally proliferating germ cells, and both act in partial redundant pathways downstream of rad-51 to prevent mitotic catastrophy. Finally, we show that topoisomerase IIIα acts independently during a late stage of meiotic recombination.


2003 ◽  
Vol 14 (11) ◽  
pp. 4707-4720 ◽  
Author(s):  
Michael G. Catlett ◽  
Susan L. Forsburg

We report the characterization of rdh54+, the second fission yeast Schizosaccharomyces pombe Rad54 homolog. rdh54+shares sequence and functional homology to budding yeast RDH54/TID1. Rdh54p is present during meiosis with appropriate timing for a meiotic recombination factor. It interacts with Rhp51 and the meiotic Rhp51 homolog Dmc1 in yeast two-hybrid assays. Deletion of rdh54+has no effect on DNA damage repair during the haploid vegetative cell cycle. In meiosis, however, rdh54Δ shows decreased spore viability and homologous recombination with a concomitant increase in sister chromatid exchange. The rdh54Δ single mutant repairs meiotic breaks with similar timing to wild type, suggesting redundancy of meiotic recombination factors. Consistent with this, the rdh54Δ rhp54Δ double mutant fails to repair meiotic double strand breaks. Live cell analysis shows that rdh54Δ rhp54Δ asci do not arrest, but undergo both meiotic divisions with near normal timing, suggesting that failure to repair double strand breaks in S. pombe meiosis does not result in checkpoint arrest.


2017 ◽  
Author(s):  
James H. Crichton ◽  
Christopher J. Playfoot ◽  
Marie MacLennan ◽  
David Read ◽  
Howard J. Cooke ◽  
...  

AbstractMeiosis relies on the SPO11 endonuclease to generate the recombinogenic DNA double strand breaks (DSBs) required for homologous chromosome synapsis and segregation. The number of meiotic DSBs needs to be sufficient to allow chromosomes to search for and find their homologs, but not excessive to the point of causing genome instability. Here we report that meiotic DSB frequency in mouse spermatocytes is regulated by the mammal-specific gene Tex19.1. We show that the chromosome asynapsis previously reported in Tex19.1-/- spermatocytes is preceded by reduced numbers of recombination foci in leptotene and zygotene. Tex19.1 is required for the generation of normal levels of Spo11-dependent DNA damage during leptotene, but not for upstream events such as MEI4 foci formation or accumulation of H3K4me3 at recombination hotspots. Furthermore, we show that mice carrying mutations in the E3 ubiquitin ligase UBR2, a TEX19.1-interacting partner, phenocopy the Tex19.1-/- recombination defects. These data show that Tex19.1 and Ubr2 are required for mouse spermatocytes to generate sufficient meiotic DSBs to ensure that homology search is consistently successful, and reveal a hitherto unknown genetic pathway regulating meiotic DSB frequency in mammals.Author SummaryMeiosis is a specialised type of cell division that occurs during sperm and egg development to reduce chromosome number prior to fertilisation. Recombination is a key step in meiosis as it facilitates the pairing of homologous chromosomes prior to their reductional division, and generates new combinations of genetic alleles for transmission in the next generation. Regulating the amount of recombination is key for successful meiosis: too much will likely cause mutations, chromosomal re-arrangements and genetic instability, whereas too little causes defects in homologous chromosome pairing prior to the meiotic divisions. This study identifies a genetic pathway requiredto generate robust meiotic recombination in mouse spermatocytes. We show that male mice with mutations in Tex19.1 or Ubr2, which encodes an E3 ubiquitin ligase that interacts with TEX19.1, have defects in generating normal levels of meiotic recombination. We show that the defects in these mutants impact on the recombination process at the stage when programmed DNA double strand breaks are being made. This defect likely contributes to the chromosome synapsis and meiotic progression phenotypes previously described in these mutant mice. This study has implications for our understanding of how this fundamental aspect of genetics and inheritance is controlled.


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