scholarly journals Aurora B kinase controls the targeting of the Astrin–SKAP complex to bioriented kinetochores

2010 ◽  
Vol 191 (2) ◽  
pp. 269-280 ◽  
Author(s):  
Jens C. Schmidt ◽  
Tomomi Kiyomitsu ◽  
Tetsuya Hori ◽  
Chelsea B. Backer ◽  
Tatsuo Fukagawa ◽  
...  
Keyword(s):  
Error Correction ◽  
Spindle Assembly Checkpoint ◽  
Multiple Roles ◽  
Aurora B ◽  
Dependent Manner ◽  
Dynein Light Chain ◽  
Chromosome Congression ◽  
Chromosome Alignment ◽  
Mitotic Delay ◽  
Associated Proteins

During mitosis, kinetochores play multiple roles to generate interactions with microtubules, and direct chromosome congression, biorientation, error correction, and anaphase segregation. However, it is unclear what changes at the kinetochore facilitate these distinct activities. Here, we describe a complex of the spindle- and kinetochore-associated protein Astrin, the small kinetochore-associated protein (SKAP), and the dynein light chain LC8. Although most dynein-associated proteins localize to unaligned kinetochores in an Aurora B–dependent manner, Astrin, SKAP, and LC8 localization is antagonized by Aurora B such that they target exclusively to bioriented kinetochores. Astrin–SKAP-depleted cells fail to maintain proper chromosome alignment, resulting in a spindle assembly checkpoint–dependent mitotic delay. Consistent with a role in stabilizing bioriented attachments, Astrin and SKAP bind directly to microtubules and are required for CLASP localization to kinetochores. In total, our results suggest that tension-dependent Aurora B phosphorylation can act to control outer kinetochore composition to provide distinct activities to prometaphase and metaphase kinetochores.

scholarly journals Sustained Mps1 activity is required in mitosis to recruit O-Mad2 to the Mad1–C-Mad2 core complex

2010 ◽  
Vol 190 (1) ◽  
pp. 25-34 ◽  
Author(s):  
Laura Hewitt ◽  
Anthony Tighe ◽  
Stefano Santaguida ◽  
Anne M. White ◽  
Clifford D. Jones ◽  
...  
Keyword(s):  
Spindle Assembly Checkpoint ◽  
Aurora B ◽  
Core Complex ◽  
Obvious Effect ◽  
Checkpoint Signaling ◽  
Mitotic Entry ◽  
The Core ◽  
Chromosome Congression ◽  
Chromosome Alignment

Mps1 is an essential component of the spindle assembly checkpoint. In this study, we describe a novel Mps1 inhibitor, AZ3146, and use it to probe the role of Mps1’s catalytic activity during mitosis. When Mps1 is inhibited before mitotic entry, subsequent recruitment of Mad1 and Mad2 to kinetochores is abolished. However, if Mps1 is inhibited after mitotic entry, the Mad1–C-Mad2 core complex remains kinetochore bound, but O-Mad2 is not recruited to the core. Although inhibiting Mps1 also interferes with chromosome alignment, we see no obvious effect on aurora B activity. In contrast, kinetochore recruitment of centromere protein E (CENP-E), a kinesin-related motor protein, is severely impaired. Strikingly, inhibition of Mps1 significantly increases its own abundance at kinetochores. Furthermore, we show that Mps1 can dimerize and transphosphorylate in cells. We propose a model whereby Mps1 transphosphorylation results in its release from kinetochores, thus facilitating recruitment of O-Mad2 and CENP-E and thereby simultaneously promoting checkpoint signaling and chromosome congression.

scholarly journals The BUBR1 pseudokinase domain promotes efficient kinetochore PP2A-B56 recruitment to regulate spindle checkpoint silencing and chromosome alignment

2019 ◽  
Author(s):  
Luciano Gama Braga ◽  
Angel F. Cisneros ◽  
Michelle Mathieu ◽  
Maxime Clerc ◽  
Pauline Garcia ◽  
...  
Keyword(s):  
Mitotic Spindle ◽  
Spindle Assembly Checkpoint ◽  
Spindle Assembly ◽  
Aurora B ◽  
Dependent Manner ◽  
Regulatory Domain ◽  
Checkpoint Protein ◽  
Major Player ◽  
Chromosome Alignment ◽  
Spindle Assembly Checkpoint Protein

ABSTRACTThe balance of phospho-signalling at outer-kinetochores during mitosis is critical for the accurate attachments between kinetochores and the mitotic spindle and timely exit from mitosis. In humans, a major player in determining this balance is the PP2A-B56 phosphatase which is recruited to the Kinase Attachment Regulatory Domain (KARD) of the Spindle Assembly Checkpoint protein Budding Uninhibited by Benzimidazole 1-related 1 (BUBR1) in a phospho-dependent manner. This event unleashes a rapid, switch-like phosphatase relay that reverses phosphorylation at the kinetochore, extinguishing the checkpoint and promoting anaphase entry. Here, we conclusively demonstrate that the pseudokinase domain of human BUBR1 lacks phosphotransfer activity and that it was maintained in vertebrates because it allosterically promotes KARD phosphorylation. Mutation or removal of this domain results in decreased PP2A-B56 recruitment to the outer kinetochore, attenuated checkpoint silencing and errors in chromosome alignment as a result of imbalance in Aurora B activity. We demonstrate that the functions of the BUBR1 pseudokinase and the BUB1 kinase domains are intertwined, providing an explanation for retention of the pseudokinase domain in certain eukaryotes.

scholarly journals Tension-Induced Error Correction and Not Kinetochore Attachment Status Activates the SAC in an Aurora-B/C-Dependent Manner in Oocytes

2018 ◽  
Vol 28 (1) ◽  
pp. 130-139.e3 ◽  
Author(s):  
Antoine Vallot ◽  
Ioanna Leontiou ◽  
Damien Cladière ◽  
Warif El Yakoubi ◽  
Susanne Bolte ◽  
...  
Keyword(s):  
Error Correction ◽  
Aurora B ◽  
Dependent Manner

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 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 Elevated polar ejection forces stabilize kinetochore–microtubule attachments

2013 ◽  
Vol 200 (2) ◽  
pp. 203-218 ◽  
Author(s):  
Stuart Cane ◽  
Anna A. Ye ◽  
Sasha J. Luks-Morgan ◽  
Thomas J. Maresca
Keyword(s):  
Molecular Motors ◽  
Molecular Mechanisms ◽  
Critical Force ◽  
Aurora B ◽  
Dependent Manner ◽  
Spindle Poles ◽  
Ejection Force ◽  
Chromosome Alignment ◽  
Directed Motility ◽  
Spindle Microtubules

Chromosome biorientation promotes congression and generates tension that stabilizes kinetochore–microtubule (kt-MT) interactions. Forces produced by molecular motors also contribute to chromosome alignment, but their impact on kt-MT attachment stability is unclear. A critical force that acts on chromosomes is the kinesin-10–dependent polar ejection force (PEF). PEFs are proposed to facilitate congression by pushing chromosomes away from spindle poles, although knowledge of the molecular mechanisms underpinning PEF generation is incomplete. Here, we describe a live-cell PEF assay in which tension was applied to chromosomes by manipulating levels of the chromokinesin NOD (no distributive disjunction; Drosophila melanogaster kinesin-10). NOD stabilized syntelic kt-MT attachments in a dose- and motor-dependent manner by overwhelming the ability of Aurora B to mediate error correction. NOD-coated chromatin stretched away from the pole via lateral and end-on interactions with microtubules, and NOD chimeras with either plus end–directed motility or tip-tracking activity produced PEFs. Thus, kt-MT attachment stability is modulated by PEFs, which can be generated by distinct force-producing interactions between chromosomes and dynamic spindle microtubules.

scholarly journals Quantitative phosphoproteomics reveals mitotic function of the ATR activator ETAA1

2019 ◽  
Vol 218 (4) ◽  
pp. 1235-1249 ◽  
Author(s):  
Thomas E. Bass ◽  
David Cortez
Keyword(s):  
Spindle Assembly Checkpoint ◽  
Kinase Activity ◽  
Aurora B ◽  
Gene Ontology Analysis ◽  
Quantitative Mass Spectrometry ◽  
Checkpoint Response ◽  
Damage Response ◽  
Chromosome Alignment ◽  
Atr Kinase ◽  
Atr Activation

The ATR kinase controls cell cycle transitions and the DNA damage response. ATR activity is regulated through two ATR-activating proteins, ETAA1 and TOPBP1. To examine how each activator contributes to ATR signaling, we used quantitative mass spectrometry to identify changes in protein phosphorylation in ETAA1- or TOPBP1-deficient cells. We identified 724, 285, and 118 phosphosites to be regulated by TOPBP1, ETAA1, or both ATR activators, respectively. Gene ontology analysis of TOPBP1- and ETAA1-dependent phosphoproteins revealed TOPBP1 to be a primary ATR activator for replication stress, while ETAA1 regulates mitotic ATR signaling. Inactivation of ATR or ETAA1, but not TOPBP1, results in decreased Aurora B kinase activity during mitosis. Additionally, ATR activation by ETAA1 is required for proper chromosome alignment during metaphase and for a fully functional spindle assembly checkpoint response. Thus, we conclude that ETAA1 and TOPBP1 regulate distinct aspects of ATR signaling with ETAA1 having a dominant function in mitotic cells.

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 Dissecting the role of MPS1 in chromosome biorientation and the spindle checkpoint through the small molecule inhibitor reversine

2010 ◽  
Vol 190 (1) ◽  
pp. 73-87 ◽  
Author(s):  
Stefano Santaguida ◽  
Anthony Tighe ◽  
Anna Morena D'Alise ◽  
Stephen S. Taylor ◽  
Andrea Musacchio
Keyword(s):  
Error Correction ◽  
Small Molecule ◽  
Spindle Assembly Checkpoint ◽  
Spindle Checkpoint ◽  
Spindle Assembly ◽  
Dependent Manner ◽  
Crucial Component ◽  
Molecule Inhibitor ◽  
The Relationship

The catalytic activity of the MPS1 kinase is crucial for the spindle assembly checkpoint and for chromosome biorientation on the mitotic spindle. We report that the small molecule reversine is a potent mitotic inhibitor of MPS1. Reversine inhibits the spindle assembly checkpoint in a dose-dependent manner. Its addition to mitotic HeLa cells causes the ejection of Mad1 and the ROD–ZWILCH–ZW10 complex, both of which are important for the spindle checkpoint, from unattached kinetochores. By using reversine, we also demonstrate that MPS1 is required for the correction of improper chromosome–microtubule attachments. We provide evidence that MPS1 acts downstream from the AURORA B kinase, another crucial component of the error correction pathway. Our experiments describe a very useful tool to interfere with MPS1 activity in human cells. They also shed light on the relationship between the error correction pathway and the spindle checkpoint and suggest that these processes are coregulated and are likely to share at least a subset of their catalytic machinery.

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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