Epigenetics regulate centromere formation and kinetochore function

2008 ◽  
Vol 104 (6) ◽  
pp. 2027-2039 ◽  
Author(s):  
Randall S. Gieni ◽  
Gordon K.T. Chan ◽  
Michael J. Hendzel
Keyword(s):  
Kinetochore Function

Specificity determinants of phosphoprotein phosphatases controlling kinetochore functions

2020 ◽  
Vol 64 (2) ◽  
pp. 325-336 ◽  
Author(s):  
Dimitriya H. Garvanska ◽  
Jakob Nilsson
Keyword(s):  
Spindle Assembly Checkpoint ◽  
Activity Level ◽  
Phosphorylation Sites ◽  
Binding Affinities ◽  
Mitotic Kinases ◽  
Anaphase Onset ◽  
Phosphoprotein Phosphatases ◽  
Linear Motifs ◽  
Temporal And Spatial ◽  
Kinetochore Function

Abstract Kinetochores are instrumental for accurate chromosome segregation by binding to microtubules in order to move chromosomes and by delaying anaphase onset through the spindle assembly checkpoint (SAC). Dynamic phosphorylation of kinetochore components is key to control these activities and is tightly regulated by temporal and spatial recruitment of kinases and phosphoprotein phosphatases (PPPs). Here we focus on PP1, PP2A-B56 and PP2A-B55, three PPPs that are important regulators of mitosis. Despite the fact that these PPPs share a very similar active site, they target unique ser/thr phosphorylation sites to control kinetochore function. Specificity is in part achieved by PPPs binding to short linear motifs (SLiMs) that guide their substrate specificity. SLiMs bind to conserved pockets on PPPs and are degenerate in nature, giving rise to a range of binding affinities. These SLiMs control the assembly of numerous substrate specifying complexes and their position and binding strength allow PPPs to target specific phosphorylation sites. In addition, the activity of PPPs is regulated by mitotic kinases and inhibitors, either directly at the activity level or through affecting PPP–SLiM interactions. Here, we discuss recent progress in understanding the regulation of PPP specificity and activity and how this controls kinetochore biology.

scholarly journals Mutational Analysis of the Drosophila Sister-Chromatid Cohesion Protein ORD and Its Role in the Maintenance of Centromeric Cohesion

Genetics ◽  
1997 ◽  
Vol 146 (4) ◽  
pp. 1319-1331 ◽  
Author(s):  
Sharon E Bickel ◽  
Dudley W Wyman ◽  
Terry L Orr-Weaver
Keyword(s):  
Sister Chromatid ◽  
Mutational Analysis ◽  
Germ Line ◽  
Sister Chromatid Cohesion ◽  
Chromosome Loss ◽  
Male And Female ◽  
Chromatid Cohesion ◽  
Random Segregation ◽  
Kinetochore Function ◽  
Segregation Of Chromosomes

The ord gene is required for proper segregation of all chromosomes in both male and female Drosophila meiosis. Here we describe the isolation of a null ord allele and examine the consequences of ablating ord function. Cytologically, meiotic sister-chromatid cohesion is severely disrupted in flies lacking ORD protein. Moreover, the frequency of missegregation in genetic tests is consistent with random segregation of chromosomes through both meiotic divisions, suggesting that sister cohesion may be completely abolished. However, only a slight decrease in viability is observed for ord null flies, indicating that ORD function is not essential for cohesion during somatic mitosis. In addition, we do not observe perturbation of germ-line mitotic divisions in flies lacking ORD activity. Our analysis of weaker ord alleles suggests that ORD is required for proper centromeric cohesion after arm cohesion is released at the metaphase I/anaphase I transition. Finally, although meiotic cohesion is abolished in the ord null fly, chromosome loss is not appreciable. Therefore, ORD activity appears to promote centromeric cohesion during meiosis II but is not essential for kinetochore function during anaphase.

scholarly journals The Spindle Checkpoint of the Yeast Saccharomyces cerevisiae Requires Kinetochore Function and Maps to the CBF3 Domain

Genetics ◽  
2001 ◽  
Vol 157 (4) ◽  
pp. 1493-1502
Author(s):  
Richard D Gardner ◽  
Atasi Poddar ◽  
Chris Yellman ◽  
Penny A Tavormina ◽  
M Cristina Monteagudo ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Critical Role ◽  
Spindle Checkpoint ◽  
Essential Genes ◽  
Gene Fusions ◽  
Yeast Saccharomyces Cerevisiae ◽  
Checkpoint Signaling ◽  
One Step ◽  
Diploid Cells ◽  
Kinetochore Function

Abstract We have measured the activity of the spindle checkpoint in null mutants lacking kinetochore activity in the yeast Saccharomyces cerevisiae. We constructed deletion mutants for nonessential genes by one-step gene replacements. We constructed heterozygous deletions of one copy of essential genes in diploid cells and purified spores containing the deletion allele. In addition, we made gene fusions for three essential genes to target the encoded proteins for proteolysis (degron alleles). We determined that Ndc10p, Ctf13p, and Cep3p are required for checkpoint activity. In contrast, cells lacking Cbf1p, Ctf19p, Mcm21p, Slk19p, Cse4p, Mif2p, Mck1p, and Kar3p are checkpoint proficient. We conclude that the kinetochore plays a critical role in checkpoint signaling in S. cerevisiae. Spindle checkpoint activity maps to a discreet domain within the kinetochore and depends on the CBF3 protein complex.

scholarly journals Meikin is a conserved regulator of meiosis-I-specific kinetochore function

Nature ◽  
2014 ◽  
Vol 517 (7535) ◽  
pp. 466-471 ◽  
Author(s):  
Jihye Kim ◽  
Kei-ichiro Ishiguro ◽  
Aya Nambu ◽  
Bungo Akiyoshi ◽  
Shihori Yokobayashi ◽  
...  
Keyword(s):  
Meiosis I ◽  
Kinetochore Function

scholarly journals Yeast Kinetochores Do Not Stabilize Stu2p-dependent Spindle Microtubule Dynamics

2003 ◽  
Vol 14 (10) ◽  
pp. 4181-4195 ◽  
Author(s):  
Chad G. Pearson ◽  
Paul S. Maddox ◽  
Ted R. Zarzar ◽  
E.D. Salmon ◽  
Kerry Bloom
Keyword(s):  
Chromosome Segregation ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Regulatory Mechanism ◽  
Metaphase Plate ◽  
Microtubule Dynamics ◽  
Spindle Microtubule ◽  
Microtubule Binding ◽  
Microtubule Stabilization ◽  
Kinetochore Function

The interaction of kinetochores with dynamic microtubules during mitosis is essential for proper centromere motility, congression to the metaphase plate, and subsequent anaphase chromosome segregation. Budding yeast has been critical in the discovery of proteins necessary for this interaction. However, the molecular mechanism for microtubule–kinetochore interactions remains poorly understood. Using live cell imaging and mutations affecting microtubule binding proteins and kinetochore function, we identify a regulatory mechanism for spindle microtubule dynamics involving Stu2p and the core kinetochore component, Ndc10p. Depleting cells of the microtubule binding protein Stu2p reduces kinetochore microtubule dynamics. Centromeres remain under tension but lack motility. Thus, normal microtubule dynamics are not required to maintain tension at the centromere. Loss of the kinetochore (ndc10-1, ndc10-2, and ctf13-30) does not drastically affect spindle microtubule turnover, indicating that Stu2p, not the kinetochore, is the foremost governor of microtubule dynamics. Disruption of kinetochore function with ndc10-1 does not affect the decrease in microtubule turnover in stu2 mutants, suggesting that the kinetochore is not required for microtubule stabilization. Remarkably, a partial kinetochore defect (ndc10-2) suppresses the decreased spindle microtubule turnover in the absence of Stu2p. These results indicate that Stu2p and Ndc10p differentially function in controlling kinetochore microtubule dynamics necessary for centromere movements.

scholarly journals Malaria Parasite Schizont Egress Antigen-1 Plays an Essential Role in Nuclear Segregation during Schizogony

mBio ◽  
2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Abigail J. Perrin ◽  
Claudine Bisson ◽  
Peter A. Faull ◽  
Matthew J. Renshaw ◽  
Rebecca A. Lees ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Vaccine Antigen ◽  
Malaria Parasites ◽  
Content Type ◽  
Dependent Protein ◽  
Low Efficiency ◽  
And Function ◽  
Parasite Egress ◽  
Kinetochore Function ◽  
Merozoite Egress

ABSTRACT Malaria parasites cause disease through repeated cycles of intraerythrocytic proliferation. Within each cycle, several rounds of DNA replication produce multinucleated forms, called schizonts, that undergo segmentation to form daughter merozoites. Upon rupture of the infected cell, the merozoites egress to invade new erythrocytes and repeat the cycle. In human malarial infections, an antibody response specific for the Plasmodium falciparum protein PF3D7_1021800 was previously associated with protection against malaria, leading to an interest in PF3D7_1021800 as a candidate vaccine antigen. Antibodies to the protein were reported to inhibit egress, resulting in it being named schizont egress antigen-1 (SEA1). A separate study found that SEA1 undergoes phosphorylation in a manner dependent upon the parasite cGMP-dependent protein kinase PKG, which triggers egress. While these findings imply a role for SEA1 in merozoite egress, this protein has also been implicated in kinetochore function during schizont development. Therefore, the function of SEA1 remains unclear. Here, we show that P. falciparum SEA1 localizes in proximity to centromeres within dividing nuclei and that conditional disruption of SEA1 expression severely impacts the distribution of DNA and formation of merozoites during schizont development, with a proportion of SEA1-null merozoites completely lacking nuclei. SEA1-null schizonts rupture, albeit with low efficiency, suggesting that neither SEA1 function nor normal segmentation is a prerequisite for egress. We conclude that SEA1 does not play a direct mechanistic role in egress but instead acts upstream of egress as an essential regulator required to ensure the correct packaging of nuclei within merozoites. IMPORTANCE Malaria is a deadly infectious disease. Rationally designed novel therapeutics will be essential for its control and eradication. The Plasmodium falciparum protein PF3D7_1021800, annotated as SEA1, is under investigation as a prospective component of a malaria vaccine, based on previous indications that antibodies to SEA1 interfere with parasite egress from infected erythrocytes. However, a consensus on the function of SEA1 is lacking. Here, we demonstrate that SEA1 localizes to dividing parasite nuclei and is necessary for the correct segregation of replicated DNA into individual daughter merozoites. In the absence of SEA1, merozoites develop defectively, often completely lacking a nucleus, and, consequently, egress is impaired and/or aberrant. Our findings provide insights into the divergent mechanisms by which intraerythrocytic malaria parasites develop and divide. Our conclusions regarding the localization and function of SEA1 are not consistent with the hypothesis that antibodies against it confer protective immunity to malaria by blocking merozoite egress.

scholarly journals Molecular requirements for the formation of a kinetochore–microtubule interface by Dam1 and Ndc80 complexes

2012 ◽  
Vol 200 (1) ◽  
pp. 21-30 ◽  
Author(s):  
Fabienne Lampert ◽  
Christine Mieck ◽  
Gregory M. Alushin ◽  
Eva Nogales ◽  
Stefan Westermann
Keyword(s):  
Chromosome Segregation ◽  
Protein Complexes ◽  
Structural Elements ◽  
Large Protein ◽  
Kinetochore Assembly ◽  
Sister Chromatids ◽  
Dam1 Complex ◽  
Shed Light ◽  
Kinetochore Function

Kinetochores are large protein complexes that link sister chromatids to the spindle and transduce microtubule dynamics into chromosome movement. In budding yeast, the kinetochore–microtubule interface is formed by the plus end–associated Dam1 complex and the kinetochore-resident Ndc80 complex, but how they work in combination and whether a physical association between them is critical for chromosome segregation is poorly understood. Here, we define structural elements required for the Ndc80–Dam1 interaction and probe their function in vivo. A novel ndc80 allele, selectively impaired in Dam1 binding, displayed growth and chromosome segregation defects. Its combination with an N-terminal truncation resulted in lethality, demonstrating essential but partially redundant roles for the Ndc80 N-tail and Ndc80–Dam1 interface. In contrast, mutations in the calponin homology domain of Ndc80 abrogated kinetochore function and were not compensated by the presence of Dam1. Our experiments shed light on how microtubule couplers cooperate and impose important constraints on structural models for outer kinetochore assembly.

scholarly journals The Yeast RSC Chromatin-Remodeling Complex Is Required for Kinetochore Function in Chromosome Segregation

2003 ◽  
Vol 23 (9) ◽  
pp. 3202-3215 ◽  
Author(s):  
Jing-mei Hsu ◽  
Jian Huang ◽  
Pamela B. Meluh ◽  
Brehon C. Laurent
Keyword(s):  
Chromatin Remodeling ◽  
Centromeric Chromatin ◽  
Centromeric Dna ◽  
Chromosome Transmission ◽  
Sister Chromatids ◽  
Chromatin Remodeling Complex ◽  
Histone H3 Variant ◽  
Complex Protein ◽  
Genes Encoding ◽  
Kinetochore Function

ABSTRACT The accurate segregation of chromosomes requires the kinetochore, a complex protein machine that assembles onto centromeric DNA to mediate attachment of replicated sister chromatids to the mitotic spindle apparatus. This study reveals an important role for the yeast RSC ATP-dependent chromatin-remodeling complex at the kinetochore in chromosome transmission. Mutations in genes encoding two core subunits of RSC, the ATPase Sth1p and the Snf5p homolog Sfh1p, interact genetically with mutations in genes encoding kinetochore proteins and with a mutation in centromeric DNA. RSC also interacts genetically and physically with the histone and histone variant components of centromeric chromatin. Importantly, RSC is localized to centromeric and centromere-proximal chromosomal regions, and its association with these loci is dependent on Sth1p. Both sth1 and sfh1 mutants exhibit altered centromeric and centromere-proximal chromatin structure and increased missegregation of authentic chromosomes. Finally, RSC is not required for centromeric deposition of the histone H3 variant Cse4p, suggesting that RSC plays a role in reconfiguring centromeric and flanking nucleosomes following Cse4p recruitment for proper chromosome transmission.

scholarly journals Kinetochore Protein Interactions and their Regulation by the Aurora Kinase Ipl1p

2003 ◽  
Vol 14 (8) ◽  
pp. 3342-3355 ◽  
Author(s):  
Ching Shang ◽  
Tony R. Hazbun ◽  
Iain M. Cheeseman ◽  
Jennifer Aranda ◽  
Stanley Fields ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Aurora Kinase ◽  
Open Reading Frames ◽  
Binding Assays ◽  
A Genome ◽  
Physical Interactions ◽  
Dam1 Complex ◽  
Two Hybrid ◽  
Kinetochore Function

Although there has been a recent explosion in the identification of budding yeast kinetochore components, the physical interactions that underlie kinetochore function remain obscure. To better understand how kinetochores attach to microtubules and how this attachment is regulated, we sought to characterize the interactions among kinetochore proteins, especially with respect to the microtubule-binding Dam1 complex. The Dam1 complex plays a crucial role in the chromosome-spindle attachment and is a key target for phospho-regulation of this attachment by the Aurora kinase Ipl1p. To identify protein–protein interactions involving the Dam1 complex, and the effects of Dam1p phosphorylation state on these physical interactions, we conducted both a genome-wide two-hybrid screen and a series of biochemical binding assays for Dam1p. A two-hybrid screen of a library of 6000 yeast open reading frames identified nine kinetochore proteins as Dam1p-interacting partners. From 113 in vitro binding reactions involving all nine subunits of the Dam1 complex and 32 kinetochore proteins, we found at least nine interactions within the Dam1 complex and 19 potential partners for the Dam1 complex. Strikingly, we found that the Dam1p–Ndc80p and Dam1p–Spc34p interactions were weakened by mutations mimicking phosphorylation at Ipl1p sites, allowing us to formulate a model for the effects of phosphoregulation on kinetochore function.

scholarly journals Novel kinetochore function of Topoisomerase IIα

Cell Cycle ◽  
2015 ◽  
Vol 14 (18) ◽  
pp. 2875-2876
Author(s):  
Duncan J Clarke
Keyword(s):  
Topoisomerase Iiα ◽  
Kinetochore Function
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