Sumoylation regulates protein dynamics during meiotic chromosome segregation in C. elegans oocytes

AbstractTimely sister chromatid separation, promoted by separase, is essential for faithful chromosome segregation. Separase is a member of the CD clan of cysteine proteases, which also includes the pro-apoptotic enzymes known as caspases. We report that the C. elegans separase SEP-1, primarily known for its role in cell division, is required for apoptosis when the predominant pro-apoptotic caspase CED-3 is compromised. Loss of SEP-1 results in extra surviving cells in a weak ced-3(−) mutant, and suppresses the embryonic lethality of a mutant defective for the apoptotic suppressor ced-9/Bcl-2. We also report apparent non-apoptotic roles for CED-3 in promoting germ cell proliferation and germline meiotic chromosome disjunction and the normal rate of embryonic development. Moreover, loss of the soma-specific (CSP-3) and germline-specific (CSP-2) caspase inhibitors results in CED-3-dependent suppression of embryonic lethality and meiotic chromosome non-disjunction respectively, when separase function is compromised. Thus, while caspases and separases have evolved different substrate specificities associated with their specialized functions in apoptosis and cell division respectively, they appear to have retained the residual ability to participate in both processes, supporting the view that co-option of components in cell division may have led to the innovation of programmed cell suicide early in metazoan evolution.

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The MAP kinase pathway coordinates crossover designation with disassembly of synaptonemal complex proteins during meiosis

eLife ◽

10.7554/elife.12039 ◽

2016 ◽

Vol 5 ◽

Cited By ~ 11

Author(s):

Saravanapriah Nadarajan ◽

Firaz Mohideen ◽

Yonatan B Tzur ◽

Nuria Ferrandiz ◽

Oliver Crawley ◽

...

Keyword(s):

Map Kinase ◽

Synaptonemal Complex ◽

Chromosome Segregation ◽

Meiotic Chromosome ◽

Late Pachytene ◽

C Elegans ◽

Map Kinase Pathway ◽

Rho Gef ◽

Kinase Signaling Pathway ◽

Kinase Pathway

Asymmetric disassembly of the synaptonemal complex (SC) is crucial for proper meiotic chromosome segregation. However, the signaling mechanisms that directly regulate this process are poorly understood. Here we show that the mammalian Rho GEF homolog, ECT-2, functions through the conserved RAS/ERK MAP kinase signaling pathway in the C. elegans germline to regulate the disassembly of SC proteins. We find that SYP-2, a SC central region component, is a potential target for MPK-1-mediated phosphorylation and that constitutively phosphorylated SYP-2 impairs the disassembly of SC proteins from chromosomal domains referred to as the long arms of the bivalents. Inactivation of MAP kinase at late pachytene is critical for timely disassembly of the SC proteins from the long arms, and is dependent on the crossover (CO) promoting factors ZHP-3/RNF212/Zip3 and COSA-1/CNTD1. We propose that the conserved MAP kinase pathway coordinates CO designation with the disassembly of SC proteins to ensure accurate chromosome segregation.

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Synaptonemal complex components are required for meiotic checkpoint function in C. elegans

10.1101/052977 ◽

2016 ◽

Author(s):

Tisha Bohr ◽

Guinevere Ashley ◽

Evan Eggleston ◽

Kyra Firestone ◽

Needhi Bhalla

Keyword(s):

Synaptonemal Complex ◽

Chromosome Segregation ◽

Meiotic Chromosome ◽

Checkpoint Response ◽

Homologous Chromosomes ◽

C Elegans ◽

Homolog Pairing ◽

The Stability ◽

Complex Components

AbstractSynapsis involves the assembly of a proteinaceous structure, the synaptonemal complex (SC), between paired homologous chromosomes and is essential for proper meiotic chromosome segregation. In C. elegans, the synapsis checkpoint selectively removes nuclei with unsynapsed chromosomes by inducing apoptosis. This checkpoint depends on Pairing Centers (PCs), cis-acting sites that promote pairing and synapsis. We have hypothesized that the stability of homolog pairing at PCs is monitored by this checkpoint. Here, we report that SC components SYP-3, HTP-3, HIM-3 and HTP-1 are required for a functional synapsis checkpoint. Mutation of these components does not abolish PC function, demonstrating they are bonafide checkpoint components. Further, we identify mutant backgrounds in which the instability of homolog pairing at PCs does not correlate with the synapsis checkpoint response. Altogether, these data suggest that, in addition to homolog pairing, SC assembly may be monitored by the synapsis checkpoint.

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Spatial and temporal control of targeting Polo-like kinase during meiotic prophase

The Journal of Cell Biology ◽

10.1083/jcb.202006094 ◽

2020 ◽

Vol 219 (11) ◽

Author(s):

James N. Brandt ◽

Katarzyna A. Hussey ◽

Yumi Kim

Keyword(s):

Chromosome Segregation ◽

Meiotic Prophase ◽

Meiotic Chromosome ◽

Holocentric Chromosomes ◽

Cyclin Dependent Kinase ◽

Chromosome Dynamics ◽

C Elegans ◽

Meiotic Progression ◽

Crossover Site ◽

Meiosis I

Polo-like kinases (PLKs) play widely conserved roles in orchestrating meiotic chromosome dynamics. However, how PLKs are targeted to distinct subcellular localizations during meiotic progression remains poorly understood. Here, we demonstrate that the cyclin-dependent kinase CDK-1 primes the recruitment of PLK-2 to the synaptonemal complex (SC) through phosphorylation of SYP-1 in C. elegans. SYP-1 phosphorylation by CDK-1 occurs just before meiotic onset. However, PLK-2 docking to the SC is prevented by the nucleoplasmic HAL-2/3 complex until crossover designation, which constrains PLK-2 to special chromosomal regions known as pairing centers to ensure proper homologue pairing and synapsis. PLK-2 is targeted to crossover sites primed by CDK-1 and spreads along the SC by reinforcing SYP-1 phosphorylation on one side of each crossover only when threshold levels of crossovers are generated. Thus, the integration of chromosome-autonomous signaling and a nucleus-wide crossover-counting mechanism partitions holocentric chromosomes relative to the crossover site, which ultimately defines the pattern of chromosome segregation during meiosis I.

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Chromosome segregation during female meiosis in C. elegans: A tale of pushing and pulling

The Journal of Cell Biology ◽

10.1083/jcb.202011035 ◽

2020 ◽

Vol 219 (12) ◽

Author(s):

Samuel J.P. Taylor ◽

Federico Pelisch

Keyword(s):

Chromosome Segregation ◽

Meiotic Chromosome ◽

Female Meiosis ◽

C Elegans ◽

Early Stages ◽

Pushing And Pulling

The role of the kinetochore during meiotic chromosome segregation in C. elegans oocytes has been a matter of controversy. Danlasky et al. (2020. J. Cell. Biol.https://doi.org/10.1083/jcb.202005179) show that kinetochore proteins KNL-1 and KNL-3 are required for early stages of anaphase during female meiosis, suggesting a new kinetochore-based model of chromosome segregation.

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Dynein-dynactin segregate meiotic chromosomes in C. elegans spermatocytes

10.1101/2020.10.19.345041 ◽

2020 ◽

Author(s):

Daniel J. Barbosa ◽

Vanessa Teixeira ◽

Joana Duro ◽

Ana X. Carvalho ◽

Reto Gassmann

Keyword(s):

Chromosome Segregation ◽

Protein Misfolding ◽

Meiotic Chromosome ◽

Spindle Assembly ◽

Cell Types ◽

Early Embryo ◽

Loss Of Function ◽

C Elegans ◽

Spindle Elongation

ABSTRACTThe dynactin complex is an essential co-factor of the microtubule-based motor dynein. Dynein-dynactin have well-documented roles in spindle assembly and positioning during C. elegans female meiosis and embryonic mitosis, while dynein-dynactin’s contribution to male meiosis has not been investigated. Here, we characterize the G33S mutation in DNC-1’s N-terminal microtubule binding domain, which corresponds to G59S in the human dynactin subunit p150/Glued that causes motor neuron disease. In spermatocytes, dnc-1(G33S) delays spindle assembly and penetrantly inhibits anaphase spindle elongation in meiosis I, which prevents homologous chromosome segregation and generates aneuploid sperm with an extra centrosome. Consequently, embryos produced by dnc-1(G33S) hermaphrodites exhibit a high incidence of tetrapolar mitotic spindles, yet dnc-1(G33S) embryos with bipolar spindles proceed through early mitotic divisions without errors in chromosome segregation. Deletion of the DNC-1 N-terminus shows that defective meiosis in dnc-1(G33S) spermatocytes is not due to DNC-1’s inability to interact with microtubules. Rather, our results suggest that the DNC-1(G33S) protein, which is aggregation-prone in vitro, is less stable in spermatocytes than the early embryo, resulting in different phenotypic severity in the two dividing tissues. Thus, the unusual hypomorphic nature of the dnc-1(G33S) mutant reveals that dynein-dynactin drive meiotic chromosome segregation in spermatocytes and illustrates that the extent to which protein misfolding leads to loss of function can vary significantly between cell types.

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Excess crossovers impede faithful meiotic chromosome segregation in C. elegans

10.1101/2020.01.30.927640 ◽

2020 ◽

Cited By ~ 2

Author(s):

Jeremy A. Hollis ◽

Marissa L. Glover ◽

Aleesa Schlientz ◽

Cori K. Cahoon ◽

Bruce Bowerman ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Chromosome Segregation ◽

High Frequency ◽

Meiotic Chromosome ◽

Dependent Manner ◽

Homologous Chromosomes ◽

Crossover Interference ◽

C Elegans ◽

Functional Consequences ◽

Chromosome Bridges

AbstractDuring meiosis, at least one crossover must form between each pair of homologous chromosomes to ensure their proper partitioning. However, most organisms limit the number of crossovers by a phenomenon called crossover interference; why this occurs is not well understood. Here we investigate the functional consequences of extra crossovers in Caenorhabditis elegans. Using a fusion chromosome that exhibits a high frequency of supernumerary crossovers, we find that essential chromosomal structures are mispatterned, subjecting chromosomes to improper spindle forces and leading to congression and segregation defects. Moreover, we uncover mechanisms that counteract these errors; anaphase I chromosome bridges were often able to resolve in a LEM-3 nuclease dependent manner, and tethers between homologs that persisted were frequently resolved during Meiosis II by a second mechanism. This study thus provides evidence that excess crossovers impact chromosome patterning and segregation, and also sheds light on how these errors are corrected.

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Sumoylation regulates central spindle protein dynamics during chromosome segregation in oocytes

10.1101/584763 ◽

2019 ◽

Author(s):

Federico Pelisch ◽

Laura Bel Borja ◽

Ellis G. Jaffray ◽

Ronald T. Hay

Keyword(s):

Protein Dynamics ◽

Chromosome Segregation ◽

Central Spindle ◽

Sumo Protease ◽

Sumo Modification ◽

C Elegans ◽

Early Anaphase ◽

Meiotic Spindles ◽

Spindle Microtubules ◽

Sumo E3 Ligase

Meiotic spindles in most species lack centrosomes and the mechanisms that underlie faithful chromosome segregation in acentrosomal meiotic spindles are not well understood. In C. elegans oocytes, spindle microtubules exert a poleward force on chromosomes dependent on the microtubule-stabilising protein CLS-2CLASP. The kinase BUB-1Bub1 and CLS-2CLASP localise in the central-spindle and display a dynamic localisation pattern throughout anaphase but the signals regulating their anaphase-specific localisation remains unknown. We have shown that SUMO regulates BUB-1 localisation during metaphase I. Here, we found that SUMO modification of BUB-1Bub1 is regulated by the SUMO E3 ligase GEI-17 and the SUMO protease ULP-1. SUMO is required for BUB-1 localisation in between segregating chromosomes during early anaphase I, and SUMO depletion partially phenocopies BUB-1Bub1 depletion. We also show that CLS-2CLASP is subject to SUMO-mediated regulation. Over-all, we provide evidence for a novel, SUMO-mediated control of protein dynamics during early anaphase I in oocytes.

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Dynein-dependent processive chromosome motions promote homologous pairing in C. elegans meiosis

The Journal of Cell Biology ◽

10.1083/jcb.201106022 ◽

2012 ◽

Vol 196 (1) ◽

pp. 47-64 ◽

Cited By ~ 63

Author(s):

David J. Wynne ◽

Ofer Rog ◽

Peter M. Carlton ◽

Abby F. Dernburg

Keyword(s):

Chromosome Segregation ◽

Meiotic Chromosome ◽

Search Rate ◽

Homologous Pairing ◽

Chromosome Dynamics ◽

C Elegans ◽

Diverse Species ◽

And Function ◽

Chromosome Motion ◽

Chromosome Regions

Meiotic chromosome segregation requires homologue pairing, synapsis, and crossover recombination, which occur during meiotic prophase. Telomere-led chromosome motion has been observed or inferred to occur during this stage in diverse species, but its mechanism and function remain enigmatic. In Caenorhabditis elegans, special chromosome regions known as pairing centers (PCs), rather than telomeres, associate with the nuclear envelope (NE) and the microtubule cytoskeleton. In this paper, we investigate chromosome dynamics in living animals through high-resolution four-dimensional fluorescence imaging and quantitative motion analysis. We find that chromosome movement is constrained before meiosis. Upon prophase onset, constraints are relaxed, and PCs initiate saltatory, processive, dynein-dependent motions along the NE. These dramatic motions are dispensable for homologous pairing and continue until synapsis is completed. These observations are consistent with the idea that motions facilitate pairing by enhancing the search rate but that their primary function is to trigger synapsis. This quantitative analysis of chromosome dynamics in a living animal extends our understanding of the mechanisms governing faithful genome inheritance.

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The conserved phosphatase GSP-2/PP1 promotes germline immortality via small RNA-mediated genome silencing during meiosis

10.1101/273722 ◽

2018 ◽

Author(s):

Katherine Kretovich Billmyre ◽

Anna-lisa Doebley ◽

Bree Heestand ◽

Tony Belicard ◽

Aya Sato-Carlton ◽

...

Keyword(s):

Germ Cell ◽

Chromosome Segregation ◽

Small Rna ◽

Protein Phosphatase ◽

Germ Line ◽

Meiotic Chromosome ◽

Loss Of Function ◽

Homologous Chromosomes ◽

C Elegans ◽

Cell Immortality

AbstractGenomic silencing can promote germ cell immortality, or transgenerational maintenance of the germ line, via mechanisms that may occur during mitosis or meiosis. Here we report that the gsp-2 PP1/Glc7 phosphatase promotes germ cell immortality. We identified a separation-of-function allele of C. elegans GSP-2 that caused a meiosis-specific chromosome segregation defect and defects in transgenerational small RNA-induced genome silencing. GSP-2 is recruited to meiotic chromosomes by LAB-1, which also promoted germ cell immortality. Sterile gsp-2 and lab-1 mutant adults displayed germline degeneration, univalents and histone phosphorylation defects in oocytes, similar to small RNA genome silencing mutants. Epistasis and RNA analysis suggested that GSP-2 functions downstream of small RNAs. We conclude that a meiosis-specific function of GSP-2/LAB-1 ties small RNA-mediated silencing of the epigenome to germ cell immortality. Given that hemizygous genetic elements can drive transgenerational epigenomic silencing, and given that LAB-1 promotes pairing of homologous chromosomes and localizes to the interface between homologous chromosomes during pachytene, we suggest that discontinuities at this interface could promote nuclear silencing in a manner that depends on GSP-2.Author SummaryThe germ line of an organism is considered immortal in its capacity to give rise to an unlimited number of future generations. To protect the integrity of the germ line, mechanisms act to suppress the accumulation of transgenerational damage to the genome or epigenome. Loss of germ cell immortality can result from mutations that disrupt the small RNA-mediated silencing pathway that helps to protect the integrity of the epigenome. Here we report for the first time that the C. elegans protein phosphatase GSP-2 that promotes core chromosome biology functions during meiosis is also required for germ cell immortality. Specifically, we identified a partial loss of function allele of gsp-2 that exhibits defects in meiotic chromosome segregation and is also dysfunctional for transgenerational small RNA-mediated genome silencing. Our results are consistent with a known role of Drosophila Protein Phosphatase 1 in heterochromatin silencing, and point to a meiotic phosphatase function that is relevant to germ cell immortality, conceivably related to its roles in chromosome pairing or sister chromatid cohesion.

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