Mitotic exit is controlled during anaphase by an Aurora B-Cyclin B1/Cdk1 crosstalk

2019 ◽  
Author(s):  
Gautam Dey
Keyword(s):  
Cyclin B1 ◽  
Mitotic Exit ◽  
Aurora B

scholarly journals Spatiotemporal control of mitotic exit during anaphase by an aurora B-Cdk1 crosstalk

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Olga Afonso ◽  
Colleen M Castellani ◽  
Liam P Cheeseman ◽  
Jorge G Ferreira ◽  
Bernardo Orr ◽  
...  
Keyword(s):  
Spindle Assembly Checkpoint ◽  
Cyclin B1 ◽  
Mitotic Exit ◽  
Aurora B ◽  
Dependent Manner ◽  
Slowing Down ◽  
Molecular Rulers ◽  
Spindle Midzone ◽  
Chromosome Separation ◽  
Chromosome Motion

According to the prevailing ‘clock’ model, chromosome decondensation and nuclear envelope reformation when cells exit mitosis are byproducts of Cdk1 inactivation at the metaphase-anaphase transition, controlled by the spindle assembly checkpoint. However, mitotic exit was recently shown to be a function of chromosome separation during anaphase, assisted by a midzone Aurora B phosphorylation gradient - the ‘ruler’ model. Here we found that Cdk1 remains active during anaphase due to ongoing APC/CCdc20- and APC/CCdh1-mediated degradation of B-type Cyclins in Drosophila and human cells. Failure to degrade B-type Cyclins during anaphase prevented mitotic exit in a Cdk1-dependent manner. Cyclin B1-Cdk1 localized at the spindle midzone in an Aurora B-dependent manner, with incompletely separated chromosomes showing the highest Cdk1 activity. Slowing down anaphase chromosome motion delayed Cyclin B1 degradation and mitotic exit in an Aurora B-dependent manner. Thus, a crosstalk between molecular ‘rulers’ and ‘clocks’ licenses mitotic exit only after proper chromosome separation.

scholarly journals Mitotic exit is controlled during anaphase by an Aurora B-Cyclin B1/Cdk1 crosstalk

2019 ◽  
Author(s):  
Olga Afonso ◽  
Liam P. Cheeseman ◽  
Luísa T. Ferreira ◽  
Eurico Morais-de-Sá ◽  
Helder Maiato
Keyword(s):  
Spindle Assembly Checkpoint ◽  
Cyclin B1 ◽  
Mitotic Exit ◽  
Aurora B ◽  
Dependent Manner ◽  
Clock Model ◽  
Molecular Rulers ◽  
Spindle Midzone ◽  
Chromosome Separation ◽  
Chromosome Decondensation

SummaryAccording to the prevailing “clock” model, chromosome decondensation and nuclear envelope reassembly during mitotic exit are byproducts of Cdk1 inactivation at the metaphase-anaphase transition, controlled by the spindle assembly checkpoint. However, mitotic exit was recently shown to be a function of chromosome separation during anaphase, assisted by a midzone Aurora B phosphorylation gradient - the “ruler” model. Here we reconciled both models by showing that Cyclin B1 degradation continues during anaphase inDrosophila, mouse and human cells, including primary tissues. This required APC/CCdh1activity, and failure to degrade Cyclin B1 during anaphase prevented mitotic exit in a Cdk1-dependent manner. Cyclin B1 localization and half-life during anaphase depended on kinesin-6, which targets Aurora B to the spindle midzone. Mechanistically, we show that anaphase duration is regulated by Aurora B-mediated phosphorylation of Cyclin B1. We propose that a crosstalk between molecular “rulers” and “clocks” licenses mitotic exit only after proper chromosome separation.

scholarly journals The Ki-67 and RepoMan mitotic phosphatases assemble via an identical, yet novel mechanism

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Ganesan Senthil Kumar ◽  
Ezgi Gokhan ◽  
Sofie De Munter ◽  
Mathieu Bollen ◽  
Paola Vagnarelli ◽  
...  
Keyword(s):  
Protein Phosphatase ◽  
Mitotic Chromosome ◽  
Cancer Therapeutics ◽  
Mitotic Exit ◽  
Protein Phosphatase 1 ◽  
Aurora B ◽  
Aurora B Kinase ◽  
Ki 67 ◽  
Anaphase Onset

Ki-67 and RepoMan have key roles during mitotic exit. Previously, we showed that Ki-67 organizes the mitotic chromosome periphery and recruits protein phosphatase 1 (PP1) to chromatin at anaphase onset, in a similar manner as RepoMan (<xref ref-type="bibr" rid="bib2">Booth et al., 2014</xref>). Here we show how Ki-67 and RepoMan form mitotic exit phosphatases by recruiting PP1, how they distinguish between distinct PP1 isoforms and how the assembly of these two holoenzymes are dynamically regulated by Aurora B kinase during mitosis. Unexpectedly, our data also reveal that Ki-67 and RepoMan bind PP1 using an identical, yet novel mechanism, interacting with a PP1 pocket that is engaged only by these two PP1 regulators. These findings not only show how two distinct mitotic exit phosphatases are recruited to their substrates, but also provide immediate opportunities for the design of novel cancer therapeutics that selectively target the Ki-67:PP1 and RepoMan:PP1 holoenzymes.

scholarly journals Loss of Cdc20 Causes a Securin-Dependent Metaphase Arrest in Two-Cell Mouse Embryos

2007 ◽  
Vol 27 (9) ◽  
pp. 3481-3488 ◽  
Author(s):  
Min Li ◽  
J. Philippe York ◽  
Pumin Zhang
Keyword(s):  
Ubiquitin Ligase ◽  
Cyclin B1 ◽  
Mitotic Exit ◽  
Adapter Proteins ◽  
Anaphase Promoting Complex ◽  
Metaphase Arrest ◽  
Cell Stage ◽  
Gene Trapping ◽  
Protein Substrates

ABSTRACT The anaphase-promoting complex/cyclosome (APC/C) is an E3 ubiquitin ligase mediating targeted proteolysis through ubiquitination of protein substrates to control the progression of mitosis. The APC/C recognizes its substrates through two adapter proteins, Cdc20 and Cdh1, which contain similar C-terminal domains composed of seven WD-40 repeats believed to be involved in interacting with their substrates. During the transition from metaphase to anaphase, APC/C-Cdc20 mediates the ubiquitination of securin and cyclin B1, allowing the activation of separase and the onset of anaphase and mitotic exit. APC/C-Cdc20 and APC/C-Cdh1 have overlapping substrates. It is unclear whether they are redundant for mitosis. Using a gene-trapping approach, we have obtained mice which lack Cdc20 function. These mice show failed embryogenesis. The embryos were arrested in metaphase at the two-cell stage with high levels of cyclin B1, indicating an essential role of Cdc20 in mitosis that is not redundant with that of Cdh1. Interestingly, Cdc20 and securin double mutant embryos could not maintain the metaphase arrest, suggesting a role of securin in preventing mitotic exit.

scholarly journals Aurora B spatially regulates EB3 phosphorylation to coordinate daughter cell adhesion with cytokinesis

2013 ◽  
Vol 201 (5) ◽  
pp. 709-724 ◽  
Author(s):  
Jorge G. Ferreira ◽  
António J. Pereira ◽  
Anna Akhmanova ◽  
Helder Maiato
Keyword(s):  
Cell Adhesion ◽  
Daughter Cell ◽  
Cortical Microtubule ◽  
Focal Adhesions ◽  
Mitotic Exit ◽  
Aurora B ◽  
Microtubule Stability ◽  
Spatiotemporal Regulation ◽  
Cytoskeleton Remodeling ◽  
Microtubule Growth

During mitosis, human cells round up, decreasing their adhesion to extracellular substrates. This must be quickly reestablished by poorly understood cytoskeleton remodeling mechanisms that prevent detachment from epithelia, while ensuring the successful completion of cytokinesis. Here we show that the microtubule end-binding (EB) proteins EB1 and EB3 play temporally distinct roles throughout cell division. Whereas EB1 was involved in spindle orientation before anaphase, EB3 was required for stabilization of focal adhesions and coordinated daughter cell spreading during mitotic exit. Additionally, EB3 promoted midbody microtubule stability and, consequently, midbody stabilization necessary for efficient cytokinesis. Importantly, daughter cell adhesion and cytokinesis completion were spatially regulated by distinct states of EB3 phosphorylation on serine 176 by Aurora B. This EB3 phosphorylation was enriched at the midbody and shown to control cortical microtubule growth. These findings uncover differential roles of EB proteins and explain the importance of an Aurora B phosphorylation gradient for the spatiotemporal regulation of microtubule function during mitotic exit and cytokinesis.

scholarly journals The spindle and kinetochore–associated (Ska) complex enhances binding of the anaphase-promoting complex/cyclosome (APC/C) to chromosomes and promotes mitotic exit

2014 ◽  
Vol 25 (5) ◽  
pp. 594-605 ◽  
Author(s):  
Sushama Sivakumar ◽  
John R. Daum ◽  
Aaron R. Tipton ◽  
Susannah Rankin ◽  
Gary J. Gorbsky
Keyword(s):  
Cyclin B1 ◽  
Mitotic Exit ◽  
Anaphase Promoting Complex ◽  
Metaphase Arrest ◽  
Microtubule Attachment ◽  
Anaphase Onset ◽  
Chromosome Alignment ◽  
Partial Degradation ◽  
Interfering Rna ◽  
Transient Alignment

The spindle and kinetochore–associated (Ska) protein complex is a heterotrimeric complex required for timely anaphase onset. The major phenotypes seen after small interfering RNA–mediated depletion of Ska are transient alignment defects followed by metaphase arrest that ultimately results in cohesion fatigue. We find that cells depleted of Ska3 arrest at metaphase with only partial degradation of cyclin B1 and securin. In cells arrested with microtubule drugs, Ska3-depleted cells exhibit slower mitotic exit when the spindle checkpoint is silenced by inhibition of the checkpoint kinase, Mps1, or when cells are forced to exit mitosis downstream of checkpoint silencing by inactivation of Cdk1. These results suggest that in addition to a role in fostering kinetochore–microtubule attachment and chromosome alignment, the Ska complex has functions in promoting anaphase onset. We find that both Ska3 and microtubules promote chromosome association of the anaphase-promoting complex/cyclosome (APC/C). Chromosome-bound APC/C shows significantly stronger ubiquitylation activity than cytoplasmic APC/C. Forced localization of Ska complex to kinetochores, independent of microtubules, results in enhanced accumulation of APC/C on chromosomes and accelerated cyclin B1 degradation during induced mitotic exit. We propose that a Ska-microtubule-kinetochore association promotes APC/C localization to chromosomes, thereby enhancing anaphase onset and mitotic exit.

Mitotic Spindle Assembly Inhibition Through Aurora A (MLN8237) Plus Vincristine Is Synthetic Lethal and Synergizes with Rituximab As a Curative Therapy in Aggressive B-Cell Non-Hodgkin Lymphoma

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2721-2721
Author(s):  
Daruka Mahadevan ◽  
Laurence Cooke ◽  
Amy Stejskal ◽  
Ann Manziello ◽  
Carla Morales ◽  
...  
Keyword(s):  
Gene Expression ◽  
Overall Survival ◽  
B Cell ◽  
Conflicts Of Interest ◽  
Tumor Regression ◽  
Single Agent ◽  
Cyclin B1 ◽  
Aurora B ◽  
Synthetic Lethal ◽  
Over Expression

Abstract Abstract 2721 Most aggressive B-cell non-Hodgkin lymphomas (B-NHL) are not curable with current chemo-immunotherapy combinations. Synthetic lethal interactions with novel agents may yield effective combination therapies with minimal toxicity for aggressive B-NHL. Auroras (A and B) are a family of mitotic oncogenic serine/threonine kinases intimately involved in high fidelity regulation of cell division. Aberrant over-expression of Auroras leads to genetic instability, polyploidy, tumor initiation and progression. Over-expression of Auroras in aggressive B-NHL promotes resistance to microtubule targeted agents (MTA, taxanes and vinca alkaloids). Si-RNA knockdown or pharmacologic inhibition of Aurora with MLN8237 [M], an ATP-site small molecule inhibitor, leads to enhanced sensitivity of B-NHL cells to MTAs. We hypothesized that promotion of microtubule de-polymerization with vincristine [V] would be more effective in synergizing with M than a microtubule polymerizing agent docetaxel [D]. We demonstrated that M plus V is synergistic while M plus D is additive in B-NHL cell culture models. Further, the addition of rituximab [R] enhanced apoptosis of B-NHL cells treated with MV or MD therapy. Mouse xenograft models of mantle cell lymphoma show modest single agent activity for M, R, D and V with tumor growth inhibition (TGI) of ∼10–15% (p=0.01). Of the doublets, MV caused tumor regression while MD and MR caused TGI (∼55–60%) and (∼20–25% (p=0.001) respectively. Although MV caused tumor regression, mice relapsed after 2 weeks of stopping therapy. In contrast, MVR had no relapses 120 days after stopping therapy, while MDR led to TGI of ∼85% (p=0.001). Kaplan-Meier analysis of overall survival showed that the mice treated with MV and MVR had a statistically significant improvement in overall survival when compared with the control (p<0.0001) or MR (p=0.0043). Gene expression profiling (human HG-U133A) and confirmatory Western blotting of harvested tumors at the end of treatment (3 weeks) confirmed reactivation of cell cycle regulatory genes including PCNA, Aurora B, cyclin B1 and cyclin D1, in MV versus MVR. Moreover, MVR therapy continues to inhibit Aurora B by repressing genes regulating mitotic sister chromatid segregation by repressed gene expression analyzed by Gene Ontology. Thus, addition of R to MV represents a novel therapeutic strategy that warrants clinical trial evaluation in aggressive B-NHL [Funded by the Lymphoma SPORE 1 P50 CA 130805 01A1]. Disclosures: No relevant conflicts of interest to declare.

scholarly journals PRC1 controls spindle polarization and recruitment of cytokinetic factors during monopolar cytokinesis

2012 ◽  
Vol 23 (7) ◽  
pp. 1196-1207 ◽  
Author(s):  
Sanjay Shrestha ◽  
Lori Jo Wilmeth ◽  
Jarrett Eyer ◽  
Charles B. Shuster
Keyword(s):  
Mitotic Exit ◽  
Aurora B ◽  
Gtpase Activating Protein ◽  
Contractile Ring ◽  
Rac Gtpase ◽  
Principal Role ◽  
Central Spindle ◽  
Ring Assembly ◽  
Diffuse Distribution ◽  
Kinesin Family

The central spindle is a postanaphase array of microtubules that plays an essential role in organizing the signaling machinery for cytokinesis. The model by which the central spindle organizes the cytokinetic apparatus is premised on an antiparallel arrangement of microtubules, yet cells lacking spindle bipolarity are capable of generating a distal domain of ectopic furrowing when forced into mitotic exit. Because protein regulator of cytokinesis (PRC1) and kinesin family member 4A (KIF4A) are believed to play a principal role in organizing the antiparallel midzone array, we sought to clarify their roles in monopolar cytokinesis. Although both factors localized to the distal ends of microtubules during monopolar cytokinesis, depletion of PRC1 and KIF4A displayed different phenotypes. Cells depleted of PRC1 failed to form a polarized microtubule array or ectopic furrows following mitotic exit, and recruitment of Aurora B kinase, male germ cell Rac GTPase-activating protein, and RhoA to the cortex was impaired. In contrast, KIF4A depletion impaired neither polarization nor ectopic furrowing, but it did result in elongated spindles with a diffuse distribution of cytokinetic factors. Thus, even in the absence of spindle bipolarity, PRC1 appears to be essential for polarizing parallel microtubules and concentrating the factors responsible for contractile ring assembly, whereas KIF4A is required for limiting the length of anaphase microtubules.

scholarly journals CDK1-mediated phosphorylation at H2B serine 6 is required for mitotic chromosome segregation

2019 ◽  
Vol 218 (4) ◽  
pp. 1164-1181 ◽  
Author(s):  
Markus Seibert ◽  
Marcus Krüger ◽  
Nikolaus A. Watson ◽  
Onur Sen ◽  
John R. Daum ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Chromosomal Instability ◽  
Mitotic Chromosome ◽  
Chromatin Modification ◽  
Genomic Stability ◽  
Cyclin B1 ◽  
Aurora B ◽  
Chromatin Binding ◽  
Histone H2b ◽  
Chromosome Separation

Faithful mitotic chromosome segregation is required for the maintenance of genomic stability. We discovered the phosphorylation of histone H2B at serine 6 (H2B S6ph) as a new chromatin modification site and found that this modification occurs during the early mitotic phases at inner centromeres and pericentromeric heterochromatin. This modification is directly mediated by cyclin B1–associated CDK1, and indirectly by Aurora B, and is antagonized by PP1-mediated dephosphorylation. H2B S6ph impairs chromatin binding of the histone chaperone SET (I2PP2A), which is important for mitotic fidelity. Injection of phosphorylation-specific H2B S6 antibodies in mitotic cells caused anaphase defects with impaired chromosome segregation and incomplete cytokinesis. As H2B S6ph is important for faithful chromosome separation, this modification may contribute to the prevention chromosomal instability and aneuploidy which frequently occur in cancer cells.

scholarly journals Combination Treatment of OSI-906 with Aurora B Inhibitor Reduces Cell Viability via Cyclin B1 Degradation-Induced Mitotic Slippage

2021 ◽  
Vol 22 (11) ◽  
pp. 5706
Author(s):  
Yuki Ikeda ◽  
Ryuji Yasutake ◽  
Ryuzaburo Yuki ◽  
Youhei Saito ◽  
Yuji Nakayama
Keyword(s):  
Cell Proliferation ◽  
Cell Viability ◽  
Combination Treatment ◽  
Spindle Assembly Checkpoint ◽  
Time Lapse ◽  
Cyclin B1 ◽  
Suppressive Effect ◽  
Aurora B ◽  
Mitotic Slippage ◽  
Chromosome Alignment

Insulin-like growth factor 1 receptor (IGF1R), a receptor-type tyrosine kinase, transduces signals related to cell proliferation, survival, and differentiation. We recently reported that OSI-906, an IGF1R inhibitor, in combination with the Aurora B inhibitor ZM447439 suppresses cell proliferation. However, the mechanism underlying this suppressive effect is yet to be elucidated. In this study, we examined the effects of combination treatment with OSI-906 and ZM447439 on cell division, so as to understand how cell proliferation was suppressed. Morphological analysis showed that the combination treatment generated enlarged cells with aberrant nuclei, whereas neither OSI-906 nor ZM447439 treatment alone caused this morphological change. Flow cytometry analysis indicated that over-replicated cells were generated by the combination treatment, but not by the lone treatment with either inhibitors. Time-lapse imaging showed mitotic slippage following a severe delay in chromosome alignment and cytokinesis failure with furrow regression. Furthermore, in S-trityl-l-cysteine–treated cells, cyclin B1 was precociously degraded. These results suggest that the combination treatment caused severe defect in the chromosome alignment and spindle assembly checkpoint, which resulted in the generation of over-replicated cells. The generation of over-replicated cells with massive aneuploidy may be the cause of reduction of cell viability and cell death. This study provides new possibilities of cancer chemotherapy.

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