scholarly journals Saccharomyces cerevisiaedeficient in the early anaphase release of Cdc14 can traverse anaphase I without ribosomal DNA disjunction and successfully complete meiosis

2021 ◽  
Author(s):  
Christopher M. Yellman
Keyword(s):  
Chromosome Segregation ◽  
Ribosomal Dna ◽  
Meiotic Chromosome ◽  
Spindle Pole ◽  
Cyclin Dependent Kinase ◽  
Binding Partner ◽  
Meiotic Progression ◽  
Nuclear Domain ◽  
Early Anaphase ◽  
Mutant Cells

ABSTRACTEukaryotic meiosis is a specialized cell cycle involving two successive nuclear divisions that lead to the formation of haploid gametes. The phosphatase Cdc14 plays an essential role in meiosis as revealed in studies of the yeastSaccharomyces cerevisiae. Cdc14 is stored in the nucleolus, a sub-nuclear domain containing the ribosomal DNA, and its release is regulated by two distinct pathways, one acting in early anaphase I of meiosis and a second at the exit from meiosis II. The early anaphase release is thought to be important for disjunction of the ribosomal DNA, disassembly of the anaphase I spindle, spindle pole re-duplication and the counteraction of CDK, all of which are required for progression into meiosis II. The release of Cdc14 from its nucleolar binding partner Net1 is stimulated by phosphorylation of cyclin-dependent kinase sites in Net1, but the importance of that phospho-regulation in meiosis is not well understood. We inducednet1-6cdkmutant cells to enter meiosis and examined the localization of Cdc14 and various indicators of meiotic progression. Thenet1-6cdkmutations inhibit, but don’t fully prevent Cdc14 release, and they almost completely prevent disjunction of the ribosomal DNA during meiosis I. Failure to disjoin the ribosomal DNA is lethal in mitosis, and we expected the same to be true in meiosis. However, the cells were able to complete meiosis II, yielding the expected four meiotic products as viable spores. Therefore, all ribosomal DNA disjunction required for meiosis can occur in meiosis II. We discuss the implications of these findings for our understanding of meiotic chromosome segregation.

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

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.

scholarly journals Mitotic Exit in the Absence of Separase Activity

2009 ◽  
Vol 20 (5) ◽  
pp. 1576-1591 ◽  
Author(s):  
Ying Lu ◽  
Frederick Cross
Keyword(s):  
Nuclear Export ◽  
Spindle Pole Body ◽  
Quantitative Measure ◽  
Spindle Pole ◽  
Mitotic Exit ◽  
Cyclin Dependent Kinase ◽  
Sister Chromatids ◽  
Early Anaphase ◽  
Mitotic Cyclin ◽  
A Minor

In budding yeast, three interdigitated pathways regulate mitotic exit (ME): mitotic cyclin–cyclin-dependent kinase (Cdk) inactivation; the Cdc14 early anaphase release (FEAR) network, including a nonproteolytic function of separase (Esp1); and the mitotic exit network (MEN) driven by interaction between the spindle pole body and the bud cortex. Here, we evaluate the contributions of these pathways to ME kinetics. Reducing Cdk activity is critical for ME, and the MEN contributes strongly to ME efficiency. Esp1 contributes to ME kinetics mainly through cohesin cleavage: the Esp1 requirement can be largely bypassed if cells are provided Esp1-independent means of separating sister chromatids. In the absence of Esp1 activity, we observed only a minor ME delay consistent with a FEAR defect. Esp1 overexpression drives ME in Cdc20-depleted cells arrested in metaphase. We have found that this activity of overexpressed Esp1 depended on spindle integrity and the MEN. We defined the first quantitative measure for Cdc14 release based on colocalization with the Net1 nucleolar anchor. This measure indicates efficient Cdc14 release upon MEN activation; release driven by Esp1 in the absence of microtubules was inefficient and incapable of driving ME. We also found a novel role for the MEN: activating Cdc14 nuclear export, even in the absence of Net1.

scholarly journals Cyclin-Specific Control of Ribosomal DNA Segregation

2008 ◽  
Vol 28 (17) ◽  
pp. 5328-5336 ◽  
Author(s):  
Matt Sullivan ◽  
Liam Holt ◽  
David O. Morgan
Keyword(s):  
Protein Kinase ◽  
Chromosome Segregation ◽  
Ribosomal Dna ◽  
S Phase ◽  
Anaphase Promoting Complex ◽  
Sister Chromatids ◽  
Early Anaphase ◽  
Mitotic Cyclin ◽  
Mitosis And Meiosis ◽  
Specific Control

ABSTRACT Following chromosome duplication in S phase of the cell cycle, the sister chromatids are linked by cohesin. At the onset of anaphase, separase cleaves cohesin and thereby initiates sister chromatid separation. Separase activation results from the destruction of its inhibitor, securin, which is triggered by a ubiquitin ligase called the anaphase-promoting complex (APC). Here, we show in budding yeast that securin destruction and, thus, separase activation are not sufficient for the efficient segregation of the repetitive ribosomal DNA (rDNA). We find that rDNA segregation also requires the APC-mediated destruction of the S-phase cyclin Clb5, an activator of the protein kinase Cdk1. Mutations that prevent Clb5 destruction are lethal and cause defects in rDNA segregation and DNA synthesis. These defects are distinct from the mitotic-exit defects caused by stabilization of the mitotic cyclin Clb2, emphasizing the importance of cyclin specificity in the regulation of late-mitotic events. Efficient rDNA segregation, both in mitosis and meiosis, also requires APC-dependent destruction of Dbf4, an activator of the protein kinase Cdc7. We speculate that the dephosphorylation of Clb5-specific Cdk1 substrates and Dbf4-Cdc7 substrates drives the resolution of rDNA in early anaphase. The coincident destruction of securin, Clb5, and Dbf4 coordinates bulk chromosome segregation with segregation of rDNA.

scholarly journals Inactivation of Mitotic Kinase Triggers Translocation of MEN Components to Mother-Daughter Neck in Yeast

2003 ◽  
Vol 14 (11) ◽  
pp. 4734-4743 ◽  
Author(s):  
Hong Hwa Lim ◽  
Foong May Yeong ◽  
Uttam Surana
Keyword(s):  
Chromosome Segregation ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Mitotic Exit ◽  
Mitotic Kinase ◽  
Division Site ◽  
Pole Body ◽  
Spindle Pole Bodies ◽  
Mitotic Exit Network ◽  
Mutant Cells

Chromosome segregation, mitotic exit, and cytokinesis are executed in this order during mitosis. Although a scheme coordinating sister chromatid separation and initiation of mitotic exit has been proposed, the mechanism that temporally links the onset of cytokinesis to mitotic exit is not known. Exit from mitosis is regulated by the mitotic exit network (MEN), which includes a GTPase (Tem1) and various kinases (Cdc15, Cdc5, Dbf2, and Dbf20). Here, we show that Dbf2 and Dbf20 functions are necessary for the execution of cytokinesis. Relocalization of these proteins from spindle pole bodies to mother daughter neck seems to be necessary for this role because cdc15-2 mutant cells, though capable of exiting mitosis at semipermissive temperature, are unable to localize Dbf2 (and Dbf20) to the “neck” and fail to undergo cytokinesis. These cells can assemble and constrict the actomyosin ring normally but are incapable of forming a septum, suggesting that MEN components are critical for the initiation of septum formation. Interestingly, the spindle pole body to neck translocation of Dbf2 and Dbf20 is triggered by the inactivation of mitotic kinase. The requirement of kinase inactivation for translocation of MEN components to the division site thus provides a mechanism that renders mitotic exit a prerequisite for cytokinesis.

scholarly journals Dissociation of the Nuf2-Ndc80 Complex Releases Centromeres from the Spindle-Pole Body during Meiotic Prophase in Fission Yeast

2005 ◽  
Vol 16 (5) ◽  
pp. 2325-2338 ◽  
Author(s):  
Haruhiko Asakawa ◽  
Aki Hayashi ◽  
Tokuko Haraguchi ◽  
Yasushi Hiraoka
Keyword(s):  
Fission Yeast ◽  
Chromosome Segregation ◽  
Meiotic Prophase ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Mating Pheromone ◽  
Pole Body ◽  
Pheromone Signaling ◽  
Ndc80 Complex ◽  
Mutant Cells

In the fission yeast Schizosaccharomyces pombe, centromeres remain clustered at the spindle-pole body (SPB) during mitotic interphase. In contrast, during meiotic prophase centromeres dissociate from the SPB. Here we examined the behavior of centromere proteins in living meiotic cells of S. pombe. We show that the Nuf2-Ndc80 complex proteins (Nuf2, Ndc80, Spc24, and Spc25) disappear from the centromere in meiotic prophase when the centromeres are separated from the SPB. The centromere protein Mis12 also dissociates during meiotic prophase; however, Mis6 remains throughout meiosis. When cells are induced to meiosis by inactivation of Pat1 kinase (a key negative regulator of meiosis), centromeres remain associated with the SPB during meiotic prophase. However, inactivation of Nuf2 by a mutation causes the release of centromeres from the SPB in pat1 mutant cells, suggesting that the Nuf2-Ndc80 complex connects centromeres to the SPB. We further found that removal of the Nuf2-Ndc80 complex from the centromere and centromere-SPB dissociation are caused by mating pheromone signaling. Because pat1 mutant cells also show aberrant chromosome segregation in the first meiotic division and this aberration is compensated by mating pheromone signaling, dissociation of the Nuf2-Ndc80 complex may be associated with remodeling of the kinetochore for meiotic chromosome segregation.

scholarly journals Mutual regulation of cyclin-dependent kinase and the mitotic exit network

2010 ◽  
Vol 188 (3) ◽  
pp. 351-368 ◽  
Author(s):  
Cornelia König ◽  
Hiromi Maekawa ◽  
Elmar Schiebel
Keyword(s):  
Spindle Pole Body ◽  
Spindle Pole ◽  
Mitotic Exit ◽  
Cyclin Dependent Kinase ◽  
Spatial Regulation ◽  
Daughter Cells ◽  
Pole Body ◽  
Mitotic Exit Network ◽  
Mutual Regulation ◽  
Early Anaphase

The mitotic exit network (MEN) is a spindle pole body (SPB)–associated, GTPase-driven signaling cascade that controls mitotic exit. The inhibitory Bfa1–Bub2 GTPase-activating protein (GAP) only associates with the daughter SPB (dSPB), raising the question as to how the MEN is regulated on the mother SPB (mSPB). Here, we show mutual regulation of cyclin-dependent kinase 1 (Cdk1) and the MEN. In early anaphase Cdk1 becomes recruited to the mSPB depending on the activity of the MEN kinase Cdc15. Conversely, Cdk1 negatively regulates binding of Cdc15 to the mSPB. In addition, Cdk1 phosphorylates the Mob1 protein to inhibit the activity of Dbf2–Mob1 kinase that regulates Cdc14 phosphatase. Our data revise the understanding of the spatial regulation of the MEN. Although MEN activity in the daughter cells is controlled by Bfa1–Bub2, Cdk1 inhibits MEN activity at the mSPB. Consistent with this model, only triple mutants that lack BUB2 and the Cdk1 phosphorylation sites in Mob1 and Cdc15 show mitotic exit defects.

scholarly journals Sli15 Associates with the Ipl1 Protein Kinase to Promote Proper Chromosome Segregation in Saccharomyces cerevisiae

1999 ◽  
Vol 145 (7) ◽  
pp. 1381-1394 ◽  
Author(s):  
Jae-hyun Kim ◽  
Jung-seog Kang ◽  
Clarence S.M. Chan
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase ◽  
Chromosome Segregation ◽  
Genetic Interaction ◽  
Spindle Pole ◽  
Mutant Phenotype ◽  
Yeast Saccharomyces Cerevisiae ◽  
Synthetic Lethal ◽  
Mutant Cells

The conserved Ipl1 protein kinase is essential for proper chromosome segregation and thus cell viability in the budding yeast Saccharomyces cerevisiae. Its human homologue has been implicated in the tumorigenesis of diverse forms of cancer. We show here that sister chromatids that have separated from each other are not properly segregated to opposite poles of ipl1-2 cells. Failures in chromosome segregation are often associated with abnormal distribution of the spindle pole–associated Nuf2-GFP protein, thus suggesting a link between potential spindle pole defects and chromosome missegregation in ipl1 mutant cells. A small fraction of ipl1-2 cells also appears to be defective in nuclear migration or bipolar spindle formation. Ipl1 associates, probably directly, with the novel and essential Sli15 protein in vivo, and both proteins are localized to the mitotic spindle. Conditional sli15 mutant cells have cytological phenotypes very similar to those of ipl1 cells, and the ipl1-2 mutation exhibits synthetic lethal genetic interaction with sli15 mutations. sli15 mutant phenotype, like ipl1 mutant phenotype, is partially suppressed by perturbations that reduce protein phosphatase 1 function. These genetic and biochemical studies indicate that Sli15 associates with Ipl1 to promote its function in chromosome segregation.

scholarly journals A novel chromosome segregation mechanism during female meiosis

2016 ◽  
Vol 27 (16) ◽  
pp. 2576-2589 ◽  
Author(s):  
Karen Perry McNally ◽  
Michelle T. Panzica ◽  
Taekyung Kim ◽  
Daniel B. Cortes ◽  
Francis J. McNally
Keyword(s):  
Chromosome Segregation ◽  
Meiotic Chromosome ◽  
Spindle Pole ◽  
Chromosome Movement ◽  
Female Meiosis ◽  
Spindle Poles ◽  
Wide Range ◽  
Chromosome Separation ◽  
Meiotic Spindles ◽  
Anaphase B

In a wide range of eukaryotes, chromosome segregation occurs through anaphase A, in which chromosomes move toward stationary spindle poles, anaphase B, in which chromosomes move at the same velocity as outwardly moving spindle poles, or both. In contrast, Caenorhabditis elegans female meiotic spindles initially shorten in the pole-to-pole axis such that spindle poles contact the outer kinetochore before the start of anaphase chromosome separation. Once the spindle pole-to-kinetochore contact has been made, the homologues of a 4-μm-long bivalent begin to separate. The spindle shortens an additional 0.5 μm until the chromosomes are embedded in the spindle poles. Chromosomes then separate at the same velocity as the spindle poles in an anaphase B–like movement. We conclude that the majority of meiotic chromosome movement is caused by shortening of the spindle to bring poles in contact with the chromosomes, followed by separation of chromosome-bound poles by outward sliding.

scholarly journals The S. pombe CDK5 Orthologue Pef1 Cooperates with Three Cyclins, Clg1, Pas1 and Psl1, to Promote Pre-Meiotic DNA Replication

Biomolecules ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 89
Author(s):  
Shinya Matsuda ◽  
Ushio Kikkawa ◽  
Akio Nakashima
Keyword(s):  
Dna Replication ◽  
Information Transfer ◽  
Cyclin Dependent Kinase ◽  
Meiotic Progression ◽  
Double Deletion ◽  
Division Process ◽  
Meiotic Initiation ◽  
Replication Factors ◽  
Mutant Cells ◽  
Cyclin Dependent Kinase 5

Meiosis is a specialized cell division process that mediates genetic information transfer to the next generation. Meiotic chromosomal segregation occurs when DNA replication is completed during the pre-meiotic S phase. Here, we show that Schizosaccharomyces pombe Pef1, an orthologue of mammalian cyclin-dependent kinase 5 (CDK5), is required to promote pre-meiotic DNA replication. We examined the efficiency of meiotic initiation using pat1-114 mutants and found that, meiotic nuclear divisions did not occur in the pef1Δ pat1-114 strain. Deletion of pef1 also suppressed the expression of DNA replication factors and the phosphorylation of Cdc2 Tyr-15. The double deletion of clg1 and psl1 arrested meiotic initiation in pat1-114 mutant cells, similar to that of pef1-deficient cells. Meiotic progression was also slightly delayed in the pas1-deficient strain. Our results reveal that Pef1 regulates cyclin-coordinated meiotic progression.

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