Crossovers trigger a remodeling of meiotic chromosome axis composition that is linked to two-step loss of sister chromatid cohesion

Sister chromatid cohesion, mediated by cohesin complexes, is laid down during DNA replication and is essential for the accurate segregation of chromosomes. Previous studies indicated that, in addition to their cohesion function, cohesins are essential for completion of recombination, pairing, meiotic chromosome axis formation, and assembly of the synaptonemal complex (SC). Using mutants in the cohesin subunit Rec8, in which phosphorylated residues were mutated to alanines, we show that cohesin phosphorylation is not only important for cohesin removal, but that cohesin's meiotic prophase functions are distinct from each other. We find pairing and SC formation to be dependent on Rec8, but independent of the presence of a sister chromatid and hence sister chromatid cohesion. We identified mutations in REC8 that differentially affect Rec8's cohesion, pairing, recombination, chromosome axis and SC assembly function. These findings define Rec8 as a key determinant of meiotic chromosome morphogenesis and a central player in multiple meiotic events.

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Double or nothing: a Drosophila mutation affecting meiotic chromosome segregation in both females and males.

Genetics ◽

10.1093/genetics/136.3.953 ◽

1994 ◽

Vol 136 (3) ◽

pp. 953-964 ◽

Cited By ~ 2

Author(s):

D P Moore ◽

W Y Miyazaki ◽

J E Tomkiel ◽

T L Orr-Weaver

Keyword(s):

Cell Death ◽

Chromosome Segregation ◽

Sister Chromatid ◽

Meiotic Chromosome ◽

Sister Chromatid Cohesion ◽

Aberrant Chromosome ◽

Chromatid Cohesion ◽

Meiotic Nondisjunction ◽

Lethal Allele ◽

Meiosis I

Abstract We describe a Drosophila mutation, Double or nothing (Dub), that causes meiotic nondisjunction in a conditional, dominant manner. Previously isolated mutations in Drosophila specifically affect meiosis either in females or males, with the exception of the mei-S332 and ord genes which are required for proper sister-chromatid cohesion. Dub is unusual in that it causes aberrant chromosome segregation almost exclusively in meiosis I in both sexes. In Dub mutant females both nonexchange and exchange chromosomes undergo nondisjunction, but the effect of Dub on nonexchange chromosomes is more pronounced. Dub reduces recombination levels slightly. Multiple nondisjoined chromosomes frequently cosegregate to the same pole. Dub results in nondisjunction of all chromosomes in meiosis I of males, although the levels are lower than in females. When homozygous, Dub is a conditional lethal allele and exhibits phenotypes consistent with cell death.

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TOP-2 is differentially required for the proper maintenance of cohesin on meiotic chromosomes in C. elegans spermatogenesis and oogenesis

10.1101/2021.12.26.474225 ◽

2021 ◽

Author(s):

Aimee Jaramillo-Lambert ◽

Christine Kiely Rourke

Keyword(s):

Sister Chromatid ◽

Topoisomerase Ii ◽

Meiotic Chromosome ◽

Sister Chromatid Cohesion ◽

Chromosome Length ◽

Aurora B ◽

Loss Of Function ◽

Late Prophase ◽

Prophase I ◽

Chromatid Cohesion

During meiotic prophase I, accurate segregation of homologous chromosomes requires the establishment of a chromosomes with a meiosis-specific architecture. Sister chromatid cohesins and the enzyme Topoisomerase II are important components of meiotic chromosome axes, but the relationship of these proteins in the context of meiotic chromosome segregation is poorly defined. Here, we analyzed the role of Topoisomerase II (TOP-2) in the timely release of sister chromatid cohesins during spermatogenesis and oogenesis of Caenorhabditis elegans. We show that there is a different requirement for TOP-2 in meiosis of spermatogenesis and oogenesis. The loss-of-function mutation top-2(it7) results in premature REC-8 removal in spermatogenesis, but not oogenesis. This is due to a failure to maintain the HORMA-domain proteins HTP-1 and HTP-2 (HTP-1/2) on chromosome axes at diakinesis and mislocalization of the downstream components that control sister chromatid cohesion release including Aurora B kinase. In oogenesis, top-2(it7) causes a delay in the localization of Aurora B to oocyte chromosomes but can be rescued through premature activation of the maturation promoting factor via knock-down of the inhibitor kinase WEE-1.3. The delay in Aurora B localization is associated with an increase in the length of diakinesis chromosomes and wee-1.3 RNAi mediated rescue of Auorora B localization in top-2(it7) is associated with a decrease in chromosome length. Our results imply that the sex-specific effects of Topoisomerase II on sister chromatid cohesion release are due to differences in the temporal regulation of meiosis and chromosome structure in late prophase I in spermatogenesis and oogenesis.

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Quantitative Cytogenetics Reveals Molecular Stoichiometry and Longitudinal Organization of Meiotic Chromosome Axes and Loops

10.1101/724997 ◽

2019 ◽

Cited By ~ 3

Author(s):

Alexander Woglar ◽

Kei Yamaya ◽

Baptiste Roelens ◽

Alistair Boettiger ◽

Simone Köhler ◽

...

Keyword(s):

Sister Chromatid ◽

De Novo ◽

Meiotic Chromosome ◽

S Phase ◽

C Elegans ◽

Sister Chromatids ◽

Chromatid Cohesion ◽

Molecular Bases ◽

Chromosome Axis ◽

Specialized Organization

ABSTRACTDuring meiosis, chromosomes adopt a specialized organization involving assembly of a cohesin-based axis along their lengths, with DNA loops emanating from this axis. We applied novel, quantitative and widely applicable cytogenetic strategies to elucidate the molecular bases of this organization using C. elegans. Analyses of WT chromosomes and de novo circular mini-chromosomes revealed that meiosis-specific HORMA-domain proteins assemble into cohorts in defined numbers and co-organize the axis together with two functionally-distinct cohesin complexes (REC-8 and COH-3/4) in defined stoichiometry. We further found that REC-8 cohesins, which load during S phase and mediate sister chromatid cohesion, usually occur as individual complexes, supporting a model wherein sister cohesion is mediated locally by a single cohesin ring. REC-8 complexes are interspersed in an alternating pattern with cohorts of axis-organizing COH-3/4 complexes (averaging three per cohort), which are insufficient to confer cohesion but can bind to individual chromatids, suggesting a mechanism to enable formation of asymmetric sister chromatid loops. Indeed, immuno-FISH assays demonstrate frequent asymmetry in genomic content between the loops formed on sister chromatids. We discuss how features of chromosome axis/loop architecture inferred from our data can help to explain enigmatic, yet essential, aspects of the meiotic program.

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Tex19.1 inhibits the N-end rule pathway and maintains acetylated SMC3 cohesin and sister chromatid cohesion in oocytes

The Journal of Cell Biology ◽

10.1083/jcb.201702123 ◽

2020 ◽

Vol 219 (5) ◽

Author(s):

Judith Reichmann ◽

Karen Dobie ◽

Lisa M. Lister ◽

James H. Crichton ◽

Diana Best ◽

...

Keyword(s):

Down Syndrome ◽

Protein Degradation ◽

Sister Chromatid ◽

Meiotic Chromosome ◽

Sister Chromatid Cohesion ◽

Protein Activity ◽

Mouse Oocytes ◽

Chromatid Cohesion ◽

Age Dependent ◽

Female Germline

Age-dependent oocyte aneuploidy, a major cause of Down syndrome, is associated with declining sister chromatid cohesion in postnatal oocytes. Here we show that cohesion in postnatal mouse oocytes is regulated by Tex19.1. We show Tex19.1−/− oocytes have defects maintaining chiasmata, missegregate their chromosomes during meiosis, and transmit aneuploidies to the next generation. Furthermore, we show that mouse Tex19.1 inhibits N-end rule protein degradation mediated by its interacting partner UBR2, and that Ubr2 itself has a previously undescribed role in negatively regulating the acetylated SMC3 subpopulation of cohesin in mitotic somatic cells. Lastly, we show that acetylated SMC3 is associated with meiotic chromosome axes in mouse oocytes, and that this population of cohesin is specifically depleted in the absence of Tex19.1. These findings indicate that Tex19.1 regulates UBR protein activity to maintain acetylated SMC3 and sister chromatid cohesion in postnatal oocytes and prevent aneuploidy from arising in the female germline.

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Tex19.1 Regulates Acetylated SMC3 Cohesin and Prevents Aneuploidy in Mouse Oocytes

10.1101/102285 ◽

2017 ◽

Cited By ~ 2

Author(s):

Judith Reichmann ◽

Karen Dobie ◽

Lisa M. Lister ◽

Diana Best ◽

James H. Crichton ◽

...

Keyword(s):

Down Syndrome ◽

Ubiquitin Ligase ◽

Sister Chromatid ◽

Meiotic Chromosome ◽

E3 Ubiquitin Ligase ◽

Sister Chromatid Cohesion ◽

Mouse Oocytes ◽

Chromatid Cohesion ◽

Age Dependent ◽

Female Germline

AbstractAge-dependent oocyte aneuploidy, a major cause of Down syndrome, is associated with declining sister chromatid cohesion in postnatal oocytes. Here we show that cohesion in postnatal mouse oocytes is regulated by Tex19.1. We show that Tex19.1-/- oocytes have defects in the maintenance of chiasmata, mis-segregate their chromosomes during meiosis, and transmit aneuploidies to the next generation. By reconstituting aspects of this pathway in mitotic somatic cells, we show that Tex19.1 regulates an acetylated SMC3-marked subpopulation of cohesin by inhibiting the activity of the E3 ubiquitin ligase UBR2 towards specific substrates, and that UBR2 itself has a previously undescribed role in negatively regulating acetylated SMC3. Lastly, we show that acetylated SMC3 is associated with meiotic chromosome axes in oocytes, but that this is reduced in the absence of Tex19.1. These findings indicate that Tex19.1 maintains acetylated SMC3 and sister chromatid cohesion in postnatal oocytes, and prevents aneuploidy in the female germline.

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Shugoshin is essential for meiotic prophase checkpoints in C. elegans

10.1101/258830 ◽

2018 ◽

Author(s):

Tisha Bohr ◽

Christian R. Nelson ◽

Stefani Giacopazzi ◽

Piero Lamelza ◽

Needhi Bhalla

Keyword(s):

Sister Chromatid ◽

Meiotic Prophase ◽

Meiotic Chromosome ◽

Sister Chromatid Cohesion ◽

Chromosomal Protein ◽

Loss Of Function ◽

Chromosome Architecture ◽

C Elegans ◽

Meiotic Chromosomes ◽

Chromatid Cohesion

AbstractThe conserved factor Shugoshin is dispensable in C. elegans for the two-step loss of sister chromatid cohesion that directs the proper segregation of meiotic chromosomes. We show that the C. elegans ortholog of Shugoshin, SGO-1, is required for checkpoint activity in meiotic prophase. This role in checkpoint function is similar to that of the meiotic chromosomal protein, HTP-3. Null sgo-1 mutants exhibit additional phenotypes similar to that of a partial loss of function allele of HTP-3: premature synaptonemal complex disassembly, the activation of alternate DNA repair pathways and an inability to recruit a conserved effector of the DNA damage pathway, HUS-1. SGO-1 localizes to pre-meiotic nuclei, when HTP-3 is present but not yet loaded onto chromosome axes, suggesting an early role in regulating meiotic chromosome metabolism. We propose that SGO-1 acts during pre-meiotic replication to ensure fully functional meiotic chromosome architecture, rendering these chromosomes competent for checkpoint activity and normal progression of meiotic recombination. Given that most research on Shugoshin has been focused on its regulation of sister chromatid cohesion in meiosis, this novel role may be conserved but previously uncharacterized in other organisms. Further, our findings expand the repertoire of Shugoshin’s functions beyond coordinating regulatory activities at the centromere.

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Genetic Interactions Between mei-S332 and ord in the Control of Sister-Chromatid Cohesion

Genetics ◽

10.1093/genetics/150.4.1467 ◽

1998 ◽

Vol 150 (4) ◽

pp. 1467-1476

Author(s):

Sharon E Bickel ◽

Daniel P Moore ◽

Cary Lai ◽

Terry L Orr-Weaver

Keyword(s):

Chromosome Segregation ◽

Sister Chromatid ◽

Double Mutant ◽

Sex Chromosome ◽

Meiotic Chromosome ◽

Sister Chromatid Cohesion ◽

Gene Products ◽

Wild Type ◽

Chromatid Cohesion ◽

Males And Females

Abstract The Drosophila mei-S332 and ord gene products are essential for proper sister-chromatid cohesion during meiosis in both males and females. We have constructed flies that contain null mutations for both genes. Double-mutant flies are viable and fertile. Therefore, the lack of an essential role for either gene in mitotic cohesion cannot be explained by compensatory activity of the two proteins during mitotic divisions. Analysis of sex chromosome segregation in the double mutant indicates that ord is epistatic to mei-S332. We demonstrate that ord is not required for MEI-S332 protein to localize to meiotic centromeres. Although overexpression of either protein in a wild-type background does not interfere with normal meiotic chromosome segregation, extra ORD+ protein in mei-S332 mutant males enhances nondisjunction at meiosis II. Our results suggest that a balance between the activity of mei-S332 and ord is required for proper regulation of meiotic cohesion and demonstrate that additional proteins must be functioning to ensure mitotic sister-chromatid cohesion.

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Meiotic cohesin STAG 3 is required for chromosome axis formation and sister chromatid cohesion

The EMBO Journal ◽

10.1002/embj.201387330 ◽

2014 ◽

Vol 33 (11) ◽

pp. 1256-1270 ◽

Cited By ~ 51

Author(s):

Tristan Winters ◽

Francois McNicoll ◽

Rolf Jessberger

Keyword(s):

Sister Chromatid ◽

Sister Chromatid Cohesion ◽

Axis Formation ◽

Chromatid Cohesion ◽

Chromosome Axis

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Phosphorylation of histone H3 is correlated with changes in the maintenance of sister chromatid cohesion during meiosis in maize, rather than the condensation of the chromatin

Journal of Cell Science ◽

10.1242/jcs.113.18.3217 ◽

2000 ◽

Vol 113 (18) ◽

pp. 3217-3226 ◽

Cited By ~ 3

Author(s):

E. Kaszas ◽

W.Z. Cande

Keyword(s):

Sister Chromatid ◽

Meiotic Chromosome ◽

Histone H3 ◽

Sister Chromatid Cohesion ◽

Chromosome Condensation ◽

Mitotic Chromosomes ◽

Sister Chromatids ◽

H3 Phosphorylation ◽

Chromatid Cohesion ◽

Metaphase I

Meiotic chromosome condensation is a unique process, characterized by dramatic changes in chromosome morphology that are required for the correct progression of pairing, synapsis, recombination and segregation of sister chromatids. We used an antibody that recognizes a ser 10 phosphoepitope on histone H3 to monitor H3 phosphorylation during meiosis in maize meiocytes. H3 phosphorylation has been reported to be an excellent marker for chromosome condensation during mitotic prophase in animal cells. In this study, we find that on maize mitotic chromosomes only pericentromeric regions are stained; there is little staining on the arms. During meiosis, chromosome condensation from leptotene through diplotene occurs in the absence of H3 phosphorylation. Instead, the changes in H3 phosphorylation at different stages of meiosis correlate with the differences in requirements for sister chromatid cohesion at different stages. Just before nuclear envelope breakdown, histone H3 phosphorylation is seen first in the pericentromeric regions and then extends through the arms at metaphase I; at metaphase II only the pericentromeric regions are stained. In afd1 (absence of first division), a mutant that is defective in many aspects of meiosis including sister chromatid cohesion and has equational separation at metaphase I, staining is restricted to the pericentromeric regions during metaphase I and anaphase I; there is no staining at metaphase II or anaphase II. We conclude that changes in the level of phosphorylation of ser10 in H3 correspond to changes in the cohesion of sister chromatids rather than the extent of chromosome condensation at different stages of meiosis.

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