scholarly journals Establishing correct kinetochore-microtubule attachments in mitosis and meiosis

2020 ◽  
Vol 64 (2) ◽  
pp. 277-287
Author(s):  
Gisela Cairo ◽  
Soni Lacefield
Keyword(s):  
Error Correction ◽  
Chromosome Segregation ◽  
Germ Cells ◽  
Chromosomal Localization ◽  
Aurora B ◽  
Molecular Pathways ◽  
Human Cell Lines ◽  
Chromosomal Passenger ◽  
Spindle Microtubules ◽  
Mitosis And Meiosis

Abstract Faithful chromosome segregation in mitosis and meiosis requires that chromosomes properly attach to spindle microtubules. Initial kinetochore-microtubule attachments are often incorrect and rely on error correction mechanisms to release improper attachments, allowing the formation of new attachments. Aurora B kinase and, in mammalian germ cells, Aurora C kinase function as the enzymatic component of the Chromosomal Passenger Complex (CPC), which localizes to the inner centromere/kinetochore and phosphorylates kinetochore proteins for microtubule release during error correction. In this review, we discuss recent findings of the molecular pathways that regulate the chromosomal localization of Aurora B and C kinases in human cell lines, mice, fission yeast, and budding yeast. We also discuss differences in the importance of localization pathways between mitosis and meiosis.

scholarly journals Phosphorylation of CENP-C by Aurora B facilitates kinetochore attachment error correction in mitosis

2017 ◽  
Vol 114 (50) ◽  
pp. E10667-E10676 ◽  
Author(s):  
Xing Zhou ◽  
Fan Zheng ◽  
Chengliang Wang ◽  
Minhao Wu ◽  
Xiaozhen Zhang ◽  
...  
Keyword(s):  
Error Correction ◽  
Chromosome Segregation ◽  
Spindle Assembly Checkpoint ◽  
Mitotic Chromosome ◽  
Regulatory Mechanism ◽  
Dynamic Interaction ◽  
Aurora B ◽  
Kinetochore Assembly ◽  
Important Pathway ◽  
Spindle Microtubules

Kinetochores are superprotein complexes that orchestrate chromosome segregation via a dynamic interaction with spindle microtubules. A physical connection between CENP-C and the Mis12–Ndc80–Knl1 (KMN) protein network is an important pathway that is used to assemble kinetochores on CENP-A nucleosomes. Multiple outer kinetochore components are phosphorylated by Aurora B kinase to activate the spindle assembly checkpoint (SAC) and to ensure accurate chromosome segregation. However, it is unknown whether Aurora B can phosphorylate inner kinetochore components to facilitate proper mitotic chromosome segregation. Here, we reported the structure of the fission yeast Schizosaccharomyces pombe Mis12–Nnf1 complex and showed that N-terminal residues 26–50 in Cnp3 (the CENP-C homolog of S. pombe) are responsible for interacting with the Mis12 complex. Interestingly, Thr28 of Cnp3 is a substrate of Ark1 (the Aurora B homolog of S. pombe), and phosphorylation impairs the interaction between the Cnp3 and Mis12 complex. The expression of a phosphorylation-mimicking Cnp3 mutant results in defective chromosome segregation due to improper kinetochore assembly. These results establish a previously uncharacterized regulatory mechanism involved in CENP-C–Mis12-facilitated kinetochore attachment error correction to ensure accurate chromosome segregation during mitosis.

scholarly journals Differential requirement for Bub1 and Bub3 in regulation of meiotic versus mitotic chromosome segregation

2020 ◽  
Vol 219 (4) ◽  
Author(s):  
Gisela Cairo ◽  
Anne M. MacKenzie ◽  
Soni Lacefield
Keyword(s):  
Chromosome Segregation ◽  
Protein Phosphatase ◽  
Mitotic Chromosome ◽  
Budding Yeast ◽  
Meiotic Chromosome ◽  
Protein Phosphatase 1 ◽  
Aurora B ◽  
Chromosome Missegregation ◽  
Anaphase Onset ◽  
Spindle Microtubules

Accurate chromosome segregation depends on the proper attachment of kinetochores to spindle microtubules before anaphase onset. The Ipl1/Aurora B kinase corrects improper attachments by phosphorylating kinetochore components and so releasing aberrant kinetochore–microtubule interactions. The localization of Ipl1 to kinetochores in budding yeast depends upon multiple pathways, including the Bub1–Bub3 pathway. We show here that in meiosis, Bub3 is crucial for correction of attachment errors. Depletion of Bub3 results in reduced levels of kinetochore-localized Ipl1 and concomitant massive chromosome missegregation caused by incorrect chromosome–spindle attachments. Depletion of Bub3 also results in shorter metaphase I and metaphase II due to premature localization of protein phosphatase 1 (PP1) to kinetochores, which antagonizes Ipl1-mediated phosphorylation. We propose a new role for the Bub1–Bub3 pathway in maintaining the balance between kinetochore localization of Ipl1 and PP1, a balance that is essential for accurate meiotic chromosome segregation and timely anaphase onset.

scholarly journals Functional Analysis of Kinetochore Assembly in Caenorhabditis elegans

2001 ◽  
Vol 153 (6) ◽  
pp. 1209-1226 ◽  
Author(s):  
Karen Oegema ◽  
Arshad Desai ◽  
Sonja Rybina ◽  
Matthew Kirkham ◽  
Anthony A. Hyman
Keyword(s):  
Caenorhabditis Elegans ◽  
Chromosome Segregation ◽  
Mitotic Chromosome ◽  
Mitotic Chromosomes ◽  
Cell Stage ◽  
Kinetochore Assembly ◽  
Chromosomal Passenger ◽  
Complete Failure ◽  
Spindle Microtubules ◽  
The One

In all eukaryotes, segregation of mitotic chromosomes requires their interaction with spindle microtubules. To dissect this interaction, we use live and fixed assays in the one-cell stage Caenorhabditis elegans embryo. We compare the consequences of depleting homologues of the centromeric histone CENP-A, the kinetochore structural component CENP-C, and the chromosomal passenger protein INCENP. Depletion of either CeCENP-A or CeCENP-C results in an identical “kinetochore null” phenotype, characterized by complete failure of mitotic chromosome segregation as well as failure to recruit other kinetochore components and to assemble a mechanically stable spindle. The similarity of their depletion phenotypes, combined with a requirement for CeCENP-A to localize CeCENP-C but not vice versa, suggest that a key step in kinetochore assembly is the recruitment of CENP-C by CENP-A–containing chromatin. Parallel analysis of CeINCENP-depleted embryos revealed mitotic chromosome segregation defects different from those observed in the absence of CeCENP-A/C. Defects are observed before and during anaphase, but the chromatin separates into two equivalently sized masses. Mechanically stable spindles assemble that show defects later in anaphase and telophase. Furthermore, kinetochore assembly and the recruitment of CeINCENP to chromosomes are independent. These results suggest distinct roles for the kinetochore and the chromosomal passengers in mitotic chromosome segregation.

scholarly journals Insights from the reconstitution of the divergent outer kinetochore of Drosophila melanogaster

Open Biology ◽  
2016 ◽  
Vol 6 (2) ◽  
pp. 150236 ◽  
Author(s):  
Yahui Liu ◽  
Arsen Petrovic ◽  
Pascaline Rombaut ◽  
Shyamal Mosalaganti ◽  
Jenny Keller ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Chromosome Segregation ◽  
Functional Organization ◽  
Histone H3 Variant ◽  
Centromeric Protein ◽  
Spindle Microtubules ◽  
Specialized Region ◽  
Structural Methods ◽  
Mitosis And Meiosis ◽  
Shed Light

Accurate chromosome segregation during mitosis and meiosis is crucial for cellular and organismal viability. Kinetochores connect chromosomes with spindle microtubules and are essential for chromosome segregation. These large protein scaffolds emerge from the centromere, a specialized region of the chromosome enriched with the histone H3 variant CENP-A. In most eukaryotes, the kinetochore core consists of the centromere-proximal constitutive centromere-associated network (CCAN), which binds CENP-A and contains 16 subunits, and of the centromere-distal Knl1 complex, Mis12 complex, Ndc80 complex (KMN) network, which binds microtubules and contains 10 subunits. In the fruitfly, Drosophila melanogaster, the kinetochore underwent remarkable simplifications. All CCAN subunits, with the exception of centromeric protein C (CENP-C), and two KMN subunits, Dsn1 and Zwint, cannot be identified in this organism. In addition, two paralogues of the KMN subunit Nnf1 (Nnf1a and Nnf1b) are present. Finally, the Spc105R subunit, homologous to human Knl1/CASC5, underwent considerable sequence changes in comparison with other organisms. We combined biochemical reconstitution with biophysical and structural methods to investigate how these changes reflect on the organization of the Drosophila KMN network. We demonstrate that the Nnf1a and Nnf1b paralogues are subunits of distinct complexes, both of which interact directly with Spc105R and with CENP-C, for the latter of which we identify a binding site on the Mis12 subunit. Our studies shed light on the structural and functional organization of a highly divergent kinetochore particle.

scholarly journals Identification of four unconventional kinetoplastid kinetochore proteins KKT22–25 in Trypanosoma brucei

Open Biology ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 190236 ◽  
Author(s):  
Olga O. Nerusheva ◽  
Patryk Ludzia ◽  
Bungo Akiyoshi
Keyword(s):  
Trypanosoma Brucei ◽  
Chromosome Segregation ◽  
Rna Binding ◽  
Affinity Purification ◽  
Potential Interaction ◽  
Interacting Proteins ◽  
Interaction Partners ◽  
Spindle Microtubules ◽  
Acetyltransferase Domain ◽  
Mitosis And Meiosis

The kinetochore is a multi-protein complex that drives chromosome segregation in eukaryotes. It assembles onto centromere DNA and interacts with spindle microtubules during mitosis and meiosis. Although most eukaryotes have canonical kinetochore proteins, kinetochores of evolutionarily divergent kinetoplastid species consist of at least 20 unconventional kinetochore proteins (KKT1–20). In addition, 12 proteins (KKT-interacting proteins 1–12, KKIP1–12) are known to localize at kinetochore regions during mitosis. It remains unclear whether KKIP proteins interact with KKT proteins. Here, we report the identification of four additional kinetochore proteins, KKT22–25, in Trypanosoma brucei . KKT22 and KKT23 constitutively localize at kinetochores, while KKT24 and KKT25 localize from S phase to anaphase. KKT23 has a Gcn5-related N -acetyltransferase domain, which is not found in any kinetochore protein known to date. We also show that KKIP1 co-purifies with KKT proteins, but not with KKIP proteins. Finally, our affinity purification of KKIP2/3/4/6 identifies a number of proteins as their potential interaction partners, many of which are implicated in RNA binding or processing. These findings further support the idea that kinetoplastid kinetochores are unconventional.

scholarly journals Bub1, Sgo1, and Mps1 mediate a distinct pathway for chromosome biorientation in budding yeast

2011 ◽  
Vol 22 (9) ◽  
pp. 1473-1485 ◽  
Author(s):  
Zuzana Storchová ◽  
Justin S. Becker ◽  
Nicolas Talarek ◽  
Sandra Kögelsberger ◽  
David Pellman
Keyword(s):  
Chromosome Segregation ◽  
Spindle Assembly Checkpoint ◽  
Budding Yeast ◽  
Spindle Pole ◽  
Growth Defect ◽  
Aurora B ◽  
Mitotic Kinase ◽  
Sister Chromatids ◽  
Chromosome Alignment ◽  
Chromosomal Passenger

The conserved mitotic kinase Bub1 performs multiple functions that are only partially characterized. Besides its role in the spindle assembly checkpoint and chromosome alignment, Bub1 is crucial for the kinetochore recruitment of multiple proteins, among them Sgo1. Both Bub1 and Sgo1 are dispensable for growth of haploid and diploid budding yeast, but they become essential in cells with higher ploidy. We find that overexpression of SGO1 partially corrects the chromosome segregation defect of bub1Δ haploid cells and restores viability to bub1Δ tetraploid cells. Using an unbiased high-copy suppressor screen, we identified two members of the chromosomal passenger complex (CPC), BIR1 (survivin) and SLI15 (INCENP, inner centromere protein), as suppressors of the growth defect of both bub1Δ and sgo1Δ tetraploids, suggesting that these mutants die due to defects in chromosome biorientation. Overexpression of BIR1 or SLI15 also complements the benomyl sensitivity of haploid bub1Δ and sgo1Δ cells. Mutants lacking SGO1 fail to biorient sister chromatids attached to the same spindle pole (syntelic attachment) after nocodazole treatment. Moreover, the sgo1Δ cells accumulate syntelic attachments in unperturbed mitoses, a defect that is partially corrected by BIR1 or SLI15 overexpression. We show that in budding yeast neither Bub1 nor Sgo1 is required for CPC localization or affects Aurora B activity. Instead we identify Sgo1 as a possible partner of Mps1, a mitotic kinase suggested to have an Aurora B–independent function in establishment of biorientation. We found that Sgo1 overexpression rescues defects caused by metaphase inactivation of Mps1 and that Mps1 is required for Sgo1 localization to the kinetochore. We propose that Bub1, Sgo1, and Mps1 facilitate chromosome biorientation independently of the Aurora B–mediated pathway at the budding yeast kinetochore and that both pathways are required for the efficient turnover of syntelic attachments.

scholarly journals The chromosomal passenger complex establishes chromosome biorientation via two parallel localization pathways

2020 ◽  
Author(s):  
Theodor Marsoner ◽  
Poornima Yedavalli ◽  
Chiara Masnovo ◽  
Katrin Schmitzer ◽  
Christopher S. Campbell
Keyword(s):  
Chromosome Segregation ◽  
Budding Yeast ◽  
Small Region ◽  
The Other ◽  
Chromosomal Passenger Complex ◽  
Microtubule Binding ◽  
Chromosome Alignment ◽  
Chromosomal Passenger ◽  
Spindle Microtubules ◽  
Do So

AbstractChromosome biorientation is established by the four-member chromosomal passenger complex (CPC) through phosphorylation of incorrect kinetochore-microtubule attachments. During chromosome alignment, the CPC localizes to the inner centromere, the inner kinetochore and spindle microtubules. Here we show that a small region of the CPC subunit INCENP/Sli15 is required to target the complex to all three of these locations in budding yeast. This region, the SAH, is essential for phosphorylation of outer kinetochore substrates, chromosome segregation, and viability. By restoring the CPC to each of these three locations individually, we found that inner centromere localization is sufficient to establish chromosome biorientation and viability independently of the other two targeting mechanisms. Remarkably, although neither the inner kinetochore nor microtubule binding activities was able to rescue viability individually, they were able to do so when combined. We have therefore identified two parallel pathways by which the CPC can promote chromosome biorientation and proper completion of mitosis.

scholarly journals Phylogenetic and Expression Analysis of CENH3 and APOLLO Genes in Sexual and Apomictic Boechera Species

2021 ◽  
Author(s):  
Evgeny Bakin ◽  
Fatih Sezer ◽  
Aslıhan Özbilen ◽  
Irem Kilic ◽  
Buket Uner ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Genetic Regulation ◽  
Single Copy ◽  
Expression Level ◽  
Egg Cell ◽  
Copy Gene ◽  
Histone H3 Variant ◽  
Before And After ◽  
Spindle Microtubules ◽  
Mitosis And Meiosis

Apomictic plants (reproducing via asexual seeds), unlike sexual individuals, avoid meiosis and egg cell fertilization. Consequently, apomixis is very important for fixing maternal genotypes in the next plant generations. Despite the progress in the study of apomixis, molecular and genetic regulation of the latter remains poorly understood. So far APOLLO (Aspartate Glutamate Aspartate Aspartate histidine exonuclease) is one of the very few described genes associated with apomixis in Boechera species. The centromere-specific histone H3 variant encoded by CENH3 gene is essential for cell division. Mutations in CENH3 disrupt chromosome segregation during mitosis and meiosis since the attachment of spindle microtubules to a mutated form of the CENH3 histone fails. This paper presents in silico characteristic of APOLLO and CENH3 genes, which may affect apomixis. Also, we characterize the structure of CENH3, study expression levels of APOLLO and CENH3 in gynoecium/siliques of the natural diploid apomictic and sexual Boechera species at the stages of before and after fertilization. While CENH3 was a single copy gene in all Boechera species, the APOLLO gene have several polymorphic alleles associated with sexual and apomictic reproduction in the Boechera genera. Expression of the APOLLO apo-allele during meiosis was upregulated in gynoecium of apomict B. divaricarpa downregulating after meiosis until 4th day after pollination (DAP). On the 5th DAP, expression in apomictic siliques increased again. In sexual B. stricta gynoecium and siliques APOLLO apo-allele did not express. Expression of the APOLLO sex-allele during and after meiosis in gynoecium of sexual plants was several times higher than that in apomictic gynoecium. However, after pollination the sex-allele was downregulated in sexual siliques to the level of apomicts and increased sharply on the 5th DAP, while in apomictic siliques it almost did not express. At the meiotic stage, the expression level of CENH3 in the gynoecium of apomicts was two times lower than that of the sexual Boechera, decreasing in both species after meiosis and keep remaining very low in siliques of both species for several days after artificial pollination until the 4th DAP, when the expression level raised in sexual B. stricta siliques exceeding 5 times the level in apomictic B. divaricarpa siliques. We also discuss polymorphism and phylogeny of the APOLLO and CENH3 genes.

scholarly journals Phylogenetic and Expression Analysis of CENH3 and APOLLO Genes in Sexual and Apomictic Boechera Species

2021 ◽  
Author(s):  
Evgeny Bakin ◽  
Fatih Sezer ◽  
Irem Kilic ◽  
Aslıhan Özbilen ◽  
Mike Rayko ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Genetic Regulation ◽  
Single Copy ◽  
Egg Cell ◽  
Expression Levels ◽  
Histone H3 Variant ◽  
Before And After ◽  
Spindle Microtubules ◽  
Mitosis And Meiosis

Apomictic plants (reproducing via asexual seeds), unlike sexual individuals, avoid meiosis and egg cell fertilization. Consequently, apomixis is very important for fixing maternal genotypes in the next plant generations. Despite the progress in the study of apomixis, molecular and genetic regulation of the latter remains poorly understood. So far APOLLO (Aspartate Glutamate Aspartate Aspartate histidine exonuclease) is the only described gene associated with apomixis in Boechera species. The centromere-specific histone H3 variant encoded by CENH3 gene is essential for cell division. Mutations in CENH3 disrupt chromosome segregation during mitosis and meiosis since the attachment of spindle microtubules to a mutated form of the CENH3 histone fails. This paper presents in silico characteristic of APOLLO and CENH3 genes, which may affect apomixis. Also, in this research we characterize the structure of CENH3, study expression levels of CENH3 and APOLLO in gynoecium/siliques of the natural diploid apomictic and sexual Boechera species at the stages of before and after fertilization. At the premeiotic stage, the expression level of CENH3 in the gynoecium of apomicts was two times lower than that of the sexual Boechera, it decreased in both species by the time of meiosis and increased after fertilization. By 1 DAP CENH3 expression started dropping in sexual B. stricta siliques and kept increasing in apomictic B. divaricarpa ones. That might indicate to a role of CENH3 in apomictic development in Boechera species. The expression levels of APOLLO also sharply decreased by the time of meiosis in gynoecium of both species; however, by 3 DAP, the level of APOLLO expression in siliques of apomicts was almost 1.5 times higher than that of the sexuals. While CENH3 was a single copy gene in all Boechera species, the APOLLO gene have several polymorphic alleles associated with sexual and apomictic reproduction in the Boechera genera. We also discuss polymorphism and phylogeny of the APOLLO and CENH3 genes.

Phosphorylation of histone H3 by Haspin regulates chromosome alignment and segregation during mitosis in maize

2020 ◽  
Author(s):  
Yang Liu ◽  
Chunhui Wang ◽  
Handong Su ◽  
James A Birchler ◽  
Fangpu Han
Keyword(s):  
Chromosome Segregation ◽  
Histone H3 ◽  
Heterochromatin Protein 1 ◽  
Heterochromatin Protein ◽  
Factor B ◽  
Microtubule Attachment ◽  
Chromosome Alignment ◽  
Chromosomal Passenger ◽  
Mitosis And Meiosis

Abstract In human cells, Haspin-mediated histone H3 threonine 3 (H3T3) phosphorylation promotes centromeric localization of the chromosomal passenger complex, thereby ensuring proper kinetochore–microtubule attachment. Haspin also binds to PDS5 cohesin-associated factor B (Pds5B), antagonizing the Wings apart-like protein homolog (Wapl)–Pds5B interaction and thus preventing Wapl from releasing centromeric cohesion during mitosis. However, the role of Haspin in plant chromosome segregation is not well understood. Here, we show that in maize (Zea mays) mitotic cells, ZmHaspin localized to the centromere during metaphase and anaphase, whereas it localized to the telomeres during meiosis. These results suggest that ZmHaspin plays different roles during mitosis and meiosis. Knockout of ZmHaspin led to decreased H3T3 phosphorylation and histone H3 serine 10 phosphorylation, and defects in chromosome alignment and segregation in mitosis. These lines of evidence suggest that Haspin regulates chromosome segregation in plants via the mechanism described for humans, namely, H3T3 phosphorylation. Plant Haspin proteins lack the RTYGA and PxVxL motifs needed to bind Pds5B and heterochromatin protein 1, and no obvious cohesion defects were detected in ZmHaspin knockout plants. Taken together, these results highlight the conserved but slightly different roles of Haspin proteins in cell division in plants and in animals.

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