scholarly journals Human kinetochores are swivel joints that mediate microtubule attachments

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Chris A Smith ◽  
Andrew D McAinsh ◽  
Nigel J Burroughs
Keyword(s):  
Chromosome Segregation ◽  
Sister Chromatid ◽  
Mitotic Spindle ◽  
Three Dimensional ◽  
Organisational Change ◽  
Mechanical Process ◽  
Spindle Poles ◽  
Chromatid Cohesion ◽  
Sister Kinetochore ◽  
Dynamic Microtubule

Chromosome segregation is a mechanical process that requires assembly of the mitotic spindle – a dynamic microtubule-based force-generating machine. Connections to this spindle are mediated by sister kinetochore pairs, that form dynamic end-on attachments to microtubules emanating from opposite spindle poles. This bi-orientation generates forces that have been reported to stretch the kinetochore itself, which has been suggested to stabilise attachment and silence the spindle checkpoint. We reveal using three dimensional tracking that the outer kinetochore domain can swivel around the inner kinetochore/centromere, which results in large reductions in intra-kinetochore distance (delta) when viewed in lower dimensions. We show that swivel provides a mechanical flexibility that enables kinetochores at the periphery of the spindle to engage microtubules. Swivel reduces as cells approach anaphase, suggesting an organisational change linked to checkpoint satisfaction and/or obligatory changes in kinetochore mechanochemistry may occur before dissolution of sister chromatid cohesion.

scholarly journals A quantitative analysis of cohesin decay in mitotic fidelity

2018 ◽  
Vol 217 (10) ◽  
pp. 3343-3353 ◽  
Author(s):  
Sara Carvalhal ◽  
Alexandra Tavares ◽  
Mariana B. Santos ◽  
Mihailo Mirkovic ◽  
Raquel A. Oliveira
Keyword(s):  
Quantitative Analysis ◽  
Chromosome Segregation ◽  
Sister Chromatid ◽  
Mitotic Spindle ◽  
Sister Chromatid Cohesion ◽  
Force Balance ◽  
Chromosome Organization ◽  
Centromeric Chromatin ◽  
Chromatid Cohesion ◽  
Chromosome Alignment

Sister chromatid cohesion mediated by cohesin is essential for mitotic fidelity. It counteracts spindle forces to prevent premature chromatid individualization and random genome segregation. However, it is unclear what effects a partial decline of cohesin may have on chromosome organization. In this study, we provide a quantitative analysis of cohesin decay by inducing acute removal of defined amounts of cohesin from metaphase-arrested chromosomes. We demonstrate that sister chromatid cohesion is very resistant to cohesin loss as chromatid disjunction is only observed when chromosomes lose >80% of bound cohesin. Removal close to this threshold leads to chromosomes that are still cohered but display compromised chromosome alignment and unstable spindle attachments. Partial cohesin decay leads to increased duration of mitosis and susceptibility to errors in chromosome segregation. We propose that high cohesin density ensures centromeric chromatin rigidity necessary to maintain a force balance with the mitotic spindle. Partial cohesin loss may lead to chromosome segregation errors even when sister chromatid cohesion is fulfilled.

scholarly journals Cohesins Determine the Attachment Manner of Kinetochores to Spindle Microtubules at Meiosis I in Fission Yeast

2003 ◽  
Vol 23 (11) ◽  
pp. 3965-3973 ◽  
Author(s):  
Shihori Yokobayashi ◽  
Masayuki Yamamoto ◽  
Yoshinori Watanabe
Keyword(s):  
Fission Yeast ◽  
Chromosome Segregation ◽  
Sister Chromatid ◽  
Specific Requirement ◽  
Spindle Poles ◽  
Chromatid Cohesion ◽  
Spindle Microtubules ◽  
Yeast Meiosis ◽  
Meiosis I ◽  
Random Division

ABSTRACT During mitosis, sister kinetochores attach to microtubules that extend to opposite spindle poles (bipolar attachment) and pull the chromatids apart at anaphase (equational segregation). A multisubunit complex called cohesin, including Rad21/Scc1, plays a crucial role in sister chromatid cohesion and equational segregation at mitosis. Meiosis I differs from mitosis in having a reductional pattern of chromosome segregation, in which sister kinetochores are attached to the same spindle (monopolar attachment). During meiosis, Rad21/Scc1 is largely replaced by its meiotic counterpart, Rec8. If Rec8 is inactivated in fission yeast, meiosis I is shifted from reductional to equational division. However, the reason rec8Δ cells undergo equational rather than random division has not been clarified; therefore, it has been unclear whether equational segregation is due to a loss of cohesin in general or to a loss of a specific requirement for Rec8. We report here that the equational segregation at meiosis I depends on substitutive Rad21, which relocates to the centromeres if Rec8 is absent. Moreover, we demonstrate that even if sufficient amounts of Rad21 are transferred to the centromeres at meiosis I, thereby establishing cohesion at the centromeres, rec8Δ cells never recover monopolar attachment but instead secure bipolar attachment. Thus, Rec8 and Rad21 define monopolar and bipolar attachment, respectively, at meiosis I. We conclude that cohesin is a crucial determinant of the attachment manner of kinetochores to the spindle microtubules at meiosis I in fission yeast.

scholarly journals A Potential Role for Human Cohesin in Mitotic Spindle Aster Assembly

2001 ◽  
Vol 276 (50) ◽  
pp. 47575-47582 ◽  
Author(s):  
Heather C. Gregson ◽  
John A. Schmiesing ◽  
Jong-Soo Kim ◽  
Toshiki Kobayashi ◽  
Sharleen Zhou ◽  
...  
Keyword(s):  
Sister Chromatid ◽  
Mitotic Spindle ◽  
Potential Role ◽  
Metaphase Plate ◽  
Spindle Pole ◽  
Sister Chromatid Cohesion ◽  
Cycle Arrest ◽  
Spindle Poles ◽  
Chromatid Cohesion

The cohesin multiprotein complex containing SMC1, SMC3, Scc3 (SA), and Scc1 (Rad21) is required for sister chromatid cohesion in eukaryotes. Although metazoan cohesin associates with chromosomes and was shown to function in the establishment of sister chromatid cohesion during interphase, the majority of cohesin was found to be off chromosomes and reside in the cytoplasm in metaphase. Despite its dissociation from chromosomes, however, microinjection of an antibody against human SMC1 led to disorganization of the metaphase plate and cell cycle arrest, indicating that human cohesin still plays an important role in metaphase. To address the mitotic function of human cohesin, the subcellular localization of cohesin components was reexamined in human cells. Interestingly, we found that cohesin localizes to the spindle poles during mitosis and interacts with NuMA, a spindle pole-associated factor required for mitotic spindle organization. The interaction with NuMA persists during interphase. Similar to NuMA, a significant amount of cohesin was found to associate with the nuclear matrix. Furthermore, in the absence of cohesin, mitotic spindle asters failed to formin vitro. Our results raise the intriguing possibility that in addition to its well demonstrated function in sister chromatid cohesion, cohesin may be involved in spindle assembly during mitosis.

scholarly journals Spindle checkpoint–independent inhibition of mitotic chromosome segregation byDrosophilaMps1

2012 ◽  
Vol 23 (12) ◽  
pp. 2275-2291 ◽  
Author(s):  
Friederike Althoff ◽  
Roger E. Karess ◽  
Christian F. Lehner
Keyword(s):  
Chromosome Segregation ◽  
Sister Chromatid ◽  
Spindle Assembly Checkpoint ◽  
Mitotic Chromosome ◽  
Independent Manner ◽  
Spindle Poles ◽  
Anaphase Onset ◽  
Chromosome Congression ◽  
Monopolar Spindle ◽  
Chromatid Cohesion

Monopolar spindle 1 (Mps1) is essential for the spindle assembly checkpoint (SAC), which prevents anaphase onset in the presence of misaligned chromosomes. Moreover, Mps1 kinase contributes in a SAC-independent manner to the correction of erroneous initial attachments of chromosomes to the spindle. Our characterization of the Drosophila homologue reveals yet another SAC-independent role. As in yeast, modest overexpression of Drosophila Mps1 is sufficient to delay progression through mitosis during metaphase, even though chromosome congression and metaphase alignment do not appear to be affected. This delay in metaphase depends on the SAC component Mad2. Although Mps1 overexpression in mad2 mutants no longer causes a metaphase delay, it perturbs anaphase. Sister kinetochores barely move apart toward spindle poles. However, kinetochore movements can be restored experimentally by separase-independent resolution of sister chromatid cohesion. We propose therefore that Mps1 inhibits sister chromatid separation in a SAC-independent manner. Moreover, we report unexpected results concerning the requirement of Mps1 dimerization and kinase activity for its kinetochore localization in Drosophila. These findings further expand Mps1's significance for faithful mitotic chromosome segregation and emphasize the importance of its careful regulation.

scholarly journals Astrin is required for the maintenance of sister chromatid cohesion and centrosome integrity

2007 ◽  
Vol 178 (3) ◽  
pp. 345-354 ◽  
Author(s):  
Kerstin H. Thein ◽  
Julia Kleylein-Sohn ◽  
Erich A. Nigg ◽  
Ulrike Gruneberg
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
Sister Chromatid ◽  
Cysteine Protease ◽  
Mitotic Spindle ◽  
Regulatory Network ◽  
Successful Completion ◽  
Sister Chromatids ◽  
Multipolar Spindles ◽  
Chromatid Cohesion

Faithful chromosome segregation in mitosis requires the formation of a bipolar mitotic spindle with stably attached chromosomes. Once all of the chromosomes are aligned, the connection between the sister chromatids is severed by the cysteine protease separase. Separase also promotes centriole disengagement at the end of mitosis. Temporal coordination of these two activities with the rest of the cell cycle is required for the successful completion of mitosis. In this study, we report that depletion of the microtubule and kinetochore protein astrin results in checkpoint-arrested cells with multipolar spindles and separated sister chromatids, which is consistent with untimely separase activation. Supporting this idea, astrin-depleted cells contain active separase, and separase depletion suppresses the premature sister chromatid separation and centriole disengagement in these cells. We suggest that astrin contributes to the regulatory network that controls separase activity.

Sister chromatid cohesion and genome stability in vertebrate cells

2003 ◽  
Vol 31 (1) ◽  
pp. 263-265 ◽  
Author(s):  
C. Morrison ◽  
P. Vagnarelli ◽  
E. Sonoda ◽  
S. Takeda ◽  
W.C. Earnshaw
Keyword(s):  
Dna Repair ◽  
Chromosome Segregation ◽  
Sister Chromatid ◽  
Genome Stability ◽  
Sister Chromatid Cohesion ◽  
Spindle Poles ◽  
Chromatid Cohesion ◽  
Chromosomal Passenger ◽  
Passenger Protein

For successful eukaryotic mitosis, sister chromatid pairs remain linked after replication until their kinetochores have been attached to opposite spindle poles by microtubules. This linkage is broken at the metaphase–anaphase transition and the sisters separate. In budding yeast, this sister chromatid cohesion requires a multi-protein complex called cohesin. A key component of cohesin is Scc1/Mcd1 (Rad21 in fission yeast). Disruption of the chicken orthologue of Scc1 by gene targeting in DT40 cells causes premature sister chromatid separation. Cohesion between sister chromatids is likely to provide a substrate for post-replicative DNA repair by homologous recombination. In keeping with this role of cohesion, Scc1 mutants also show defects in the repair of spontaneous and induced DNA damage. Scc1-deficient cells frequently fail to complete metaphase chromosome alignment and show chromosome segregation defects, suggesting aberrant kinetochore function. Consistent with this, the chromosomal passenger protein, INCENP (inner centromere protein) fails to localize to centromeres. Survivin, another passenger protein and one which interacts with INCENP, also fails to localize to centromeres in Scc1-deficient cells. These results show that cohesin maintains genomic stability by ensuring appropriate DNA repair and equal chromosome segregation at mitosis.

scholarly journals Chromosome bi-orientation on the mitotic spindle

2005 ◽  
Vol 360 (1455) ◽  
pp. 581-589 ◽  
Author(s):  
Tomoyuki U Tanaka
Keyword(s):  
Protein Kinase ◽  
Chromosome Segregation ◽  
Mitotic Spindle ◽  
Budding Yeast ◽  
Aurora B ◽  
Cohesin Complex ◽  
Spindle Poles ◽  
Anaphase Onset ◽  
Sister Kinetochore ◽  
Dependent Mechanism

For proper chromosome segregation, sister kinetochores must attach to microtubules extending from opposite spindle poles prior to anaphase onset. This state is called sister kinetochore bi-orientation or chromosome bi-orientation. The mechanism ensuring chromosome bi-orientation lies at the heart of chromosome segregation, but is still poorly understood. Recent evidence suggests that mal-oriented kinetochore-to-pole connections are corrected in a tension-dependent mechanism. The cohesin complex and the Ipl1/Aurora B protein kinase seem to be key regulators for this correction. In this article, I discuss how cells ensure sister kinetochore bi-orientation for all chromosomes, mainly focusing on our recent findings in budding yeast.

scholarly journals Multiple Subunits of the Caenorhabditis elegans Anaphase-Promoting Complex Are Required for Chromosome Segregation During Meiosis I

Genetics ◽  
2002 ◽  
Vol 160 (2) ◽  
pp. 805-813 ◽  
Author(s):  
Edward S Davis ◽  
Lucia Wille ◽  
Barry A Chestnut ◽  
Penny L Sadler ◽  
Diane C Shakes ◽  
...  
Keyword(s):  
Rna Interference ◽  
Caenorhabditis Elegans ◽  
Chromosome Segregation ◽  
Sister Chromatid ◽  
Sister Chromatid Cohesion ◽  
Anaphase Promoting Complex ◽  
Genetic Screens ◽  
Chromatid Cohesion ◽  
Interference Studies ◽  
Meiosis I

Abstract Two genes, originally identified in genetic screens for Caenorhabditis elegans mutants that arrest in metaphase of meiosis I, prove to encode subunits of the anaphase-promoting complex or cyclosome (APC/C). RNA interference studies reveal that these and other APC/C subunits are essential for the segregation of chromosomal homologs during meiosis I. Further, chromosome segregation during meiosis I requires APC/C functions in addition to the release of sister chromatid cohesion.

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

Genetics ◽  
1994 ◽  
Vol 136 (3) ◽  
pp. 953-964 ◽  
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.

scholarly journals Genes Involved in Sister Chromatid Separation and Segregation in the Budding Yeast Saccharomyces cerevisiae

Genetics ◽  
2001 ◽  
Vol 159 (2) ◽  
pp. 453-470
Author(s):  
Sue Biggins ◽  
Needhi Bhalla ◽  
Amy Chang ◽  
Dana L Smith ◽  
Andrew W Murray
Keyword(s):  
Chromosome Segregation ◽  
Sister Chromatid ◽  
Mitotic Spindle ◽  
Budding Yeast ◽  
Temperature Sensitive ◽  
Chromosome Behavior ◽  
Yeast Saccharomyces Cerevisiae ◽  
Sister Chromatids ◽  
Marked Chromosome ◽  
Sister Chromatid Separation

Abstract Accurate chromosome segregation requires the precise coordination of events during the cell cycle. Replicated sister chromatids are held together while they are properly attached to and aligned by the mitotic spindle at metaphase. At anaphase, the links between sisters must be promptly dissolved to allow the mitotic spindle to rapidly separate them to opposite poles. To isolate genes involved in chromosome behavior during mitosis, we microscopically screened a temperature-sensitive collection of budding yeast mutants that contain a GFP-marked chromosome. Nine LOC (loss of cohesion) complementation groups that do not segregate sister chromatids at anaphase were identified. We cloned the corresponding genes and performed secondary tests to determine their function in chromosome behavior. We determined that three LOC genes, PDS1, ESP1, and YCS4, are required for sister chromatid separation and three other LOC genes, CSE4, IPL1, and SMT3, are required for chromosome segregation. We isolated alleles of two genes involved in splicing, PRP16 and PRP19, which impair α-tubulin synthesis thus preventing spindle assembly, as well as an allele of CDC7 that is defective in DNA replication. We also report an initial characterization of phenotypes associated with the SMT3/SUMO gene and the isolation of WSS1, a high-copy smt3 suppressor.

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