scholarly journals Heat Stress Interferes with Formation of Double-Strand Breaks and Homolog Synapsis in Arabidopsis thaliana

2020 ◽  
Author(s):  
Yingjie Ning ◽  
Qingpei Liu ◽  
Chong Wang ◽  
Erdai Qin ◽  
Zhihua Wu ◽  
...  
Keyword(s):  
Heat Stress ◽  
Central Element ◽  
Double Strand Breaks ◽  
Genomic Diversity ◽  
Rt Pcr ◽  
Genetic Studies ◽  
Lateral Element ◽  
Strand Breaks ◽  
Downstream Effects ◽  
Chromosome Axis

AbstractMeiotic recombination (MR) drives novel combination of alleles and contributes to genomic diversity in eukaryotes. In this study, we showed that heat stress (36-38°C) over fertile threshold fully abolished crossover (CO) formation in Arabidopsis. Cytological and genetic studies in wild-type plants, and the syn1 and rad51 mutants suggested that heat stress reduces generation of SPO11-dependent double-strand breaks (DSBs). In support, the abundance of recombinase DMC1, which is required for MR-specific DSB repair, was significantly reduced under heat stress. In addition, we showed that high temperatures induced disassembly and/or instability of ASY4-but not SYN1-mediated chromosome axis. At the same time, ASY1-associated lateral element of synaptonemal complex (SC) was partially affected, while the ZYP1-dependent central element of SC was disrupted, indicating that heat stress impairs SC formation. Moreover, quantitative RT-PCR revealed that genes involved in DSB formation; e.g. SPO11-1, PRD1, 2 and 3, were not impacted; however, recombinase RAD51 and chromosome axis factors ASY3 and ASY4 were significantly downregulated under heat stress. Taken together, these findings revealed that heat stress inhibits MR via compromised DSB formation and homolog synapsis, which are possible downstream effects of the impacted chromosome axis. Our study thus provides evidence shedding light on how increase of environmental temperature influences MR in Arabidopsis.

scholarly journals The Zip4 protein directly couples meiotic crossover formation to synaptonemal complex assembly

2021 ◽  
Author(s):  
Alexandra Pyatnitskaya ◽  
Jessica Andreani ◽  
Raphaël Guérois ◽  
Arnaud De Muyt ◽  
Valérie Borde
Keyword(s):  
Synaptonemal Complex ◽  
Central Element ◽  
Underlying Mechanism ◽  
Double Strand Breaks ◽  
General Mechanism ◽  
Strand Breaks ◽  
Homologous Chromosomes ◽  
Evolutionarily Conserved ◽  
Meiotic Crossover ◽  
Chromosome Axis

Meiotic recombination is triggered by programmed double-strand breaks (DSBs), a subset of these being repaired as crossovers, promoted by eight evolutionarily conserved proteins, named ZMM. Crossover formation is functionally linked to synaptonemal complex (SC) assembly between homologous chromosomes, but the underlying mechanism is unknown. Here we show that Ecm11, a SC central element protein, localizes on both DSB sites and sites that attach chromatin loops to the chromosome axis, which are the starting points of SC formation, in a way that strictly requires the ZMM protein Zip4. Furthermore, Zip4 directly interacts with Ecm11, and point mutants that specifically abolish this interaction lose Ecm11 binding to chromosomes and exhibit defective SC assembly. This can be partially rescued by artificially tethering interaction-defective Ecm11 to Zip4. Mechanistically, this direct connection ensuring SC assembly from CO sites could be a way for the meiotic cell to shut down further DSB formation once enough recombination sites have been selected for crossovers, thereby preventing excess crossovers. Finally, the mammalian ortholog of Zip4, TEX11, also interacts with the SC central element TEX12, suggesting a general mechanism.

scholarly journals The Zip4 protein directly couples meiotic crossover formation to synaptonemal complex assembly

2021 ◽  
Author(s):  
Alexandra Pyatnitskaya ◽  
Jessica Andreani ◽  
Raphael Guerois ◽  
Arnaud De Muyt ◽  
Valerie Borde
Keyword(s):  
Synaptonemal Complex ◽  
Central Element ◽  
Underlying Mechanism ◽  
Double Strand Breaks ◽  
General Mechanism ◽  
Strand Breaks ◽  
Homologous Chromosomes ◽  
Evolutionarily Conserved ◽  
Meiotic Crossover ◽  
Chromosome Axis

Meiotic recombination is triggered by programmed double-strand breaks (DSBs), a subset of these being repaired as crossovers, promoted by eight evolutionarily conserved proteins, named ZMM. Crossover formation is functionally linked to synaptonemal complex (SC) assembly between homologous chromosomes, but the underlying mechanism is unknown. Here we show that Ecm11, a SC central element protein, localizes on both DSB sites and sites that attach chromatin loops to the chromosome axis, which are the starting points of SC formation, in a way that strictly requires the ZMM protein Zip4. Furthermore, Zip4 directly interacts with Ecm11 and point mutants that specifically abolish this interaction lose Ecm11 binding to chromosomes and exhibit defective SC assembly. This can be partially rescued by artificially tethering interaction-defective Ecm11 to Zip4. Mechanistically, this direct connection ensuring SC assembly from CO sites could be a way for the meiotic cell to shut down further DSB formation once enough recombination sites have been selected for crossovers, thereby preventing excess crossovers. Finally, the mammalian ortholog of Zip4, TEX11, also interacts with the SC central element TEX12, suggesting a general mechanism.

scholarly journals Modelling sex-specific crossover patterning in Arabidopsis

2018 ◽  
Author(s):  
Andrew Lloyd ◽  
Eric Jenczewski
Keyword(s):  
Mechanical Model ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Female Meiosis ◽  
Recombination Rates ◽  
Data Set ◽  
Strand Breaks ◽  
Film Model ◽  
Chromosome Axis ◽  
Complex Length

ABSTRACTInterference is a major force governing the patterning of meiotic crossovers. A leading model describing how interference influences crossover-patterning is the beam film model, a mechanical model based on the accumulation and redistribution of crossover-promoting stress along the chromosome axis. We use the beam-film model in conjunction with a large Arabidopsis reciprocal back-cross data set to gain mechanistic insights into the differences between male and female meiosis and crossover patterning. Beam-film modelling suggests that the underlying mechanics of crossover patterning and interference are identical in the two sexes, with the large difference in recombination rates and distributions able to be entirely explained by the shorter chromosome axes in females. The modelling supports previous indications that fewer crossovers occur via the class II pathway in female meiosis and that this could be explained by reduced DNA double strand breaks in female meiosis, paralleling the observed reduction in synaptonemal complex length between the two sexes. We also demonstrate that changes in the strength of suppression of neighboring class I crossovers can have opposite effects on effective interference depending on the distance between two genetic intervals.

scholarly journals Modelling Sex-Specific Crossover Patterning in Arabidopsis

Genetics ◽  
2019 ◽  
Vol 211 (3) ◽  
pp. 847-859 ◽  
Author(s):  
Andrew Lloyd ◽  
Eric Jenczewski
Keyword(s):  
Mechanical Model ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Female Meiosis ◽  
Recombination Rates ◽  
Data Set ◽  
Strand Breaks ◽  
Film Model ◽  
Chromosome Axis ◽  
Complex Length

“Interference” is a major force governing the patterning of meiotic crossovers. A leading model describing how interference influences crossover patterning is the beam-film model, a mechanical model based on the accumulation and redistribution of crossover-promoting “stress” along the chromosome axis. We use the beam-film model in conjunction with a large Arabidopsis reciprocal backcross data set to gain “mechanistic” insights into the differences between male and female meiosis, and crossover patterning. Beam-film modeling suggests that the underlying mechanics of crossover patterning and interference are identical in the two sexes, with the large difference in recombination rates and distributions able to be entirely explained by the shorter chromosome axes in females. The modeling supports previous indications that fewer crossovers occur via the class II pathway in female meiosis and that this could be explained by reduced DNA double-strand breaks in female meiosis, paralleling the observed reduction in synaptonemal complex length between the two sexes. We also demonstrate that changes in the strength of suppression of neighboring class I crossovers can have opposite effects on “effective” interference depending on the distance between two genetic intervals.

scholarly journals Genetic Interactions of Histone Modification Machinery Set1 and PAF1C with the Recombination Complex Rec114-Mer2-Mei4 in the Formation of Meiotic DNA Double-Strand Breaks

2020 ◽  
Vol 21 (8) ◽  
pp. 2679
Author(s):  
Ying Zhang ◽  
Takuya Suzuki ◽  
Ke Li ◽  
Santosh K. Gothwal ◽  
Miki Shinohara ◽  
...  
Keyword(s):  
Histone Modification ◽  
Genetic Interaction ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
H3k4 Methylation ◽  
Yeast Saccharomyces Cerevisiae ◽  
Strand Breaks ◽  
Histone H3k4 ◽  
Genomic Locations ◽  
Chromosome Axis

Homologous recombination is essential for chromosome segregation during meiosis I. Meiotic recombination is initiated by the introduction of double-strand breaks (DSBs) at specific genomic locations called hotspots, which are catalyzed by Spo11 and its partners. DSB hotspots during meiosis are marked with Set1-mediated histone H3K4 methylation. The Spo11 partner complex, Rec114-Mer2-Mei4, essential for the DSB formation, localizes to the chromosome axes. For efficient DSB formation, a hotspot with histone H3K4 methylation on the chromatin loops is tethered to the chromosome axis through the H3K4 methylation reader protein, Spp1, on the axes, which interacts with Mer2. In this study, we found genetic interaction of mutants in a histone modification protein complex called PAF1C with the REC114 and MER2 in the DSB formation in budding yeast Saccharomyces cerevisiae. Namely, the paf1c mutations rtf1 and cdc73 showed synthetic defects in meiotic DSB formation only when combined with a wild-type-like tagged allele of either the REC114 or MER2. The synthetic defect of the tagged REC114 allele in the DSB formation was seen also with the set1, but not with spp1 deletion. These results suggest a novel role of histone modification machinery in DSB formation during meiosis, which is independent of Spp1-mediated loop-axis tethering.

Loss Of NIPA Leads To Defects In The Repair Of DNA Double Strand Breaks In Mice

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2488-2488
Author(s):  
Anna Lena Illert ◽  
Cristina Antinozzi ◽  
Hiroyuki Kawaguchi ◽  
Michal Kulinski ◽  
Christine Klitzing ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Meiotic Prophase ◽  
Conflicts Of Interest ◽  
Cyclin B1 ◽  
Double Strand Breaks ◽  
Conditional Knockout ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Chromosome Axis

Abstract Regulated oscillation of protein expression is an essential mechanism of cell cycle control. The SCF class of E3 ubiquitin ligases is involved in this process by targeting cell cycle regulatory proteins for degradation by the proteasome. We previously reported the cloning of NIPA (Nuclear Interaction Partner of ALK) in complex with constitutively active oncogenic fusions of ALK, which contributes to the development of lymphomas and sarcomas. Subsequently we characterized NIPA as a F-Box protein that defines an oscillating ubiquitin E3 ligase targeting nuclear cyclin B1 in interphase thus contributing to the timing of mitotic entry. Using a conditional knockout strategy we inactivated the gene encoding Nipa. Nipa-deficient animals are viable, but show a lower birth rate and a reduced body weight. Furthermore, Nipa-deficient males were sterile due to a block of spermatogenesis during meiotic prophase. Virtually no spermatocytes progress beyond a late-zygotene to early-pachytene stage and reach an aberrant stage, with synaptonemal complex disassembly and incomplete synapsis. Nipa-/- females are sub-fertile with an early and severe meiotic defect during embryogenesis with extensive apoptosis in early prophase (E13.5-E14.5). Here we report, that Nipa-/- meiocytes exhibit persistent cytological markers for DNA double strand break repair proteins (like DMC1, RAD51) in meiotic prophase with more than twice as many DMC1 foci as control animals. Kinetic analysis of the first wave of spermatogenesis showed increased DMC1/RAD51 foci in Nipa-/- cells as soon as early-pachynema cells appear (13-14 days post partum). Moreover, we show that Nipa deficiency does not lead to a defect in meiotic sex chromosome inactivation despite epithelial stage IV apoptosis. Nipa-deficient spermatocytes exhibit numerous abnormalities in staining of chromosome axis associated proteins (like SYCP3 and STAG3) indicating that chromosome axis defects were associated with compromised chromosome axis integrity leading to overt chromosome fragmentation. Further in vitro analyses with bleomycin treated MEFs displayed high pH2AX levels in cells lacking NIPA. Repair of DNA DSB seemed to be abolished in these cells as the pH2AX-level were sustained and still visible after 90 min of timecourse, where wildtype cells already repaired sides of DNA Damage. Consistent with these findings NIPA-deficient spleen cells showed compromised DNA Damage repair measured in a comet assay with a significantly longer olive tail moment in NIPA knockout cells under repair conditions. Taken together, the phenotype of Nipa-knockout mice is a definitive proof of the meiotic significance of NIPA and our results show a new, unsuspected role of NIPA in chromosome stability and the repair of DNA double strand breaks. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Meiotic Crossover Patterning

2021 ◽  
Vol 9 ◽  
Author(s):  
Nila M. Pazhayam ◽  
Carolyn A. Turcotte ◽  
Jeff Sekelsky
Keyword(s):  
Chromosome Segregation ◽  
Chromosome Pair ◽  
Double Strand Breaks ◽  
Current Understanding ◽  
Genetic Studies ◽  
Strand Breaks ◽  
Proper Number ◽  
Key Players ◽  
Meiotic Crossover ◽  
History Of

Proper number and placement of meiotic crossovers is vital to chromosome segregation, with failures in normal crossover distribution often resulting in aneuploidy and infertility. Meiotic crossovers are formed via homologous repair of programmed double-strand breaks (DSBs). Although DSBs occur throughout the genome, crossover placement is intricately patterned, as observed first in early genetic studies by Muller and Sturtevant. Three types of patterning events have been identified. Interference, first described by Sturtevant in 1915, is a phenomenon in which crossovers on the same chromosome do not occur near one another. Assurance, initially identified by Owen in 1949, describes the phenomenon in which a minimum of one crossover is formed per chromosome pair. Suppression, first observed by Beadle in 1932, dictates that crossovers do not occur in regions surrounding the centromere and telomeres. The mechanisms behind crossover patterning remain largely unknown, and key players appear to act at all scales, from the DNA level to inter-chromosome interactions. There is also considerable overlap between the known players that drive each patterning phenomenon. In this review we discuss the history of studies of crossover patterning, developments in methods used in the field, and our current understanding of the interplay between patterning phenomena.

scholarly journals The bakers’s yeast Msh4-Msh5 associates with double-strand break hotspots and chromosome axis during meiosis to promote crossovers

2020 ◽  
Author(s):  
Krishnaprasad G. Nandanan ◽  
Ajith V. Pankajam ◽  
Sagar Salim ◽  
Miki Shinohara ◽  
Gen Lin ◽  
...  
Keyword(s):  
Mismatch Repair ◽  
Baker’S Yeast ◽  
Double Strand Breaks ◽  
Holliday Junction ◽  
Baker's Yeast ◽  
Strand Breaks ◽  
Homologous Chromosomes ◽  
Genome Wide ◽  
Chromosome Axis

ABSTRACTSegregation of homologous chromosomes during the first meiotic division requires at least one obligate crossover/exchange event between the homolog pairs. In the baker’s yeast Saccharomyces cerevisiae and mammals, the mismatch repair-related factors, Msh4-Msh5 and Mlh1-Mlh3 generate the majority of the meiotic crossovers from programmed double-strand breaks (DSBs). To understand the mechanistic role of Msh4-Msh5 in meiotic crossing over, we performed genome-wide ChIP-sequencing and cytological analysis of the Msh5 protein in cells synchronized for meiosis. We observe that Msh5 associates with DSB hotspots, chromosome axis, and centromeres. We found that the initial recruitment of Msh4-Msh5 occurs following DSB resection. A two-step Msh5 binding pattern was observed: an early weak binding at DSB hotspots followed by enhanced late binding upon the formation of double Holliday junction structures. Msh5 association with the chromosome axis is Red1 dependent, while Msh5 association with the DSB hotspots and axis is dependent on DSB formation by Spo11. Msh5 binding was enhanced at strong DSB hotspots consistent with a role for DSB frequency in promoting Msh5 binding. These data on the in vivo localization of Msh5 during meiosis have implications for how Msh4-Msh5 may work with other crossover and synapsis promoting factors to ensure Holliday junction resolution at the chromosome axis.AUTHOR SUMMARYDuring meiosis, crossovers facilitate physical linkages between homologous chromosomes that ensure their accurate segregation. Meiotic crossovers are initiated from programmed DNA double-strand breaks (DSBs). In the baker’s yeast and mammals, DSBs are repaired into crossovers primarily through a pathway involving the highly conserved mismatch repair related Msh4-Msh5 complex along with other crossover promoting factors. In vitro and physical studies suggest that the Msh4-Msh5 heterodimer facilitates meiotic crossover formation by stabilizing Holliday junctions. We investigated the genome-wide in vivo binding sites of Msh5 during meiotic progression. Msh5 was enriched at DSB hotspots, chromosome axis, and centromere sites. Our results suggest Msh5 associates with both DSB sites on the chromosomal loops and with the chromosome axis to promote crossover formation. These results on the in vivo dynamic localization of the Msh5 protein provide novel insights into how the Msh4-Msh5 complex may work with other crossover and synapsis promoting factors to facilitate crossover formation.

scholarly journals Sycp1 Is Not Required for Subtelomeric DNA Double-Strand Breaks but Is Required for Homologous Alignment in Zebrafish Spermatocytes

2021 ◽  
Vol 9 ◽  
Author(s):  
Yukiko Imai ◽  
Kenji Saito ◽  
Kazumasa Takemoto ◽  
Fabien Velilla ◽  
Toshihiro Kawasaki ◽  
...  
Keyword(s):  
Synaptonemal Complex ◽  
Central Element ◽  
Double Strand Breaks ◽  
Dependent Manner ◽  
Wild Type ◽  
Dna Double Strand Breaks ◽  
Gene Encoding ◽  
Strand Breaks ◽  
Stop Mutation ◽  
Filament Protein

In meiotic prophase I, homologous chromosomes are bound together by the synaptonemal complex, in which two axial elements are connected by transverse filaments and central element proteins. In human and zebrafish spermatocytes, homologous recombination and assembly of the synaptonemal complex initiate predominantly near telomeres. In mice, synapsis is not required for meiotic double-strand breaks (DSBs) and homolog alignment but is required for DSB repair; however, the interplay of these meiotic events in the context of peritelomeric bias remains unclear. In this study, we identified a premature stop mutation in the zebrafish gene encoding the transverse filament protein Sycp1. Insycp1mutant zebrafish spermatocytes, axial elements were formed and paired at chromosome ends between homologs during early to mid-zygonema. However, they did not synapse, and their associations were mostly lost in late zygotene- or pachytene-like stages. Insycp1mutant spermatocytes, γH2AX signals were observed, and Dmc1/Rad51 and RPA signals appeared predominantly near telomeres, resembling wild-type phenotypes. We observed persistent localization of Hormad1 along the axis insycp1mutant spermatocytes, while the majority of Iho1 signals appeared and disappeared with kinetics similar to those in wild-type spermatocytes. Notably, persistent Iho1 foci were observed inspo11mutant spermatocytes, suggesting that Iho1 dissociation from axes occurs in a DSB-dependent manner. Our results demonstrated that Sycp1 is not required for peritelomeric DSB formation but is necessary for complete pairing of homologs in zebrafish meiosis.

scholarly journals Multilayered mechanisms ensure that short chromosomes recombine in meiosis

2018 ◽  
Author(s):  
Hajime Murakami ◽  
Isabel Lam ◽  
Jacquelyn Song ◽  
Megan van Overbeek ◽  
Scott Keeney
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Selection Pressure ◽  
Homologous Chromosome ◽  
Replication Timing ◽  
Double Strand Breaks ◽  
Strand Breaks ◽  
Homologous Chromosomes ◽  
Chromosome Axis

To segregate accurately during meiosis, homologous chromosomes in most species must recombine. Very small chromosomes would risk missegregation if recombination were randomly distributed, so the double-strand breaks (DSBs) that initiate recombination are not haphazard. How this nonrandomness is controlled is not under-stood. Here we demonstrate that Saccharomyces cerevisiae integrates multiple, temporally distinct pathways to regulate chromosomal binding of pro-DSB factors Rec114 and Mer2, thereby controlling duration of a DSB-competent state. Homologous chromosome engagement regulates Rec114/Mer2 dissociation late in prophase, whereas replication timing and proximity to centromeres or telomeres influence timing and amount of Rec114/Mer2 accumulation early. A distinct early mechanism boosts Rec114/Mer2 binding quickly to high levels specifically on the shortest chromosomes, dependent on chromosome axis proteins and subject to selection pressure to maintain hyperrecombinogenic properties of these chromosomes. Thus, an organism’s karyotype and its attendant risk of meiotic missegregation influence the shape and evolution of its recombination landscape.

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