Faculty Opinions recommendation of Mps1 phosphorylates Borealin to control Aurora B activity and chromosome alignment.

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.

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Faculty Opinions recommendation of Mps1 phosphorylates Borealin to control Aurora B activity and chromosome alignment.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1100098.556422 ◽

2008 ◽

Author(s):

Domenico Grieco

Keyword(s):

Aurora B ◽

Chromosome Alignment

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Elevated polar ejection forces stabilize kinetochore–microtubule attachments

The Journal of Cell Biology ◽

10.1083/jcb.201211119 ◽

2013 ◽

Vol 200 (2) ◽

pp. 203-218 ◽

Cited By ~ 49

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.

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Quantitative phosphoproteomics reveals mitotic function of the ATR activator ETAA1

The Journal of Cell Biology ◽

10.1083/jcb.201810058 ◽

2019 ◽

Vol 218 (4) ◽

pp. 1235-1249 ◽

Cited By ~ 20

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.

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

International Journal of Molecular Sciences ◽

10.3390/ijms22115706 ◽

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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Biochemical characterization of GSK1070916, a potent and selective inhibitor of Aurora B and Aurora C kinases with an extremely long residence time1

Biochemical Journal ◽

10.1042/bj20090121 ◽

2009 ◽

Vol 420 (2) ◽

pp. 259-265 ◽

Cited By ~ 38

Author(s):

Kelly Anderson ◽

Zhihong Lai ◽

Octerloney B. Mcdonald ◽

J. Darren Stuart ◽

Eldridge N. Nartey ◽

...

Keyword(s):

Biochemical Characterization ◽

Enzyme Inhibitor ◽

Competitive Inhibitor ◽

Tumour Regression ◽

Aurora B ◽

Aurora Kinases ◽

Chromosome Alignment ◽

Xenograft Models ◽

Protein Enzyme

The Aurora kinases AurA, B and C are serine/threonine protein kinases that play essential roles in mitosis and cytokinesis. Among them, AurB is required for maintaining proper chromosome alignment, separation and segregation during mitosis, and regulating a number of critical processes involved in cytokinesis. AurB overexpression has been observed in a variety of cancer cell lines, and inhibition of AurB has been shown to induce tumour regression in mouse xenograft models. In the present study we report the enzymatic characterization of a potent and selective AurB/AurC inhibitor. GSK1070916 is a reversible and ATP-competitive inhibitor of the AurB–INCENP (inner centromere protein) enzyme. It selectively inhibits AurB–INCENP (Ki*=0.38±0.29 nM) and AurC–INCENP (Ki*=1.5±0.4 nM) over AurA–TPX2 (target protein for Xenopus kinesin-like protein 2) (Ki=490±60 nM). Inhibition of AurB–INCENP and AurC–INCENP is time-dependent, with an enzyme-inhibitor dissociation half-life of >480 min and 270±28 min respectively. The extremely slow rate of dissociation from the AurB and AurC enzymes distinguishes GSK1070916 from two other Aurora inhibitors in the clinic, AZD1152 and VX-680 (also known as MK-0457).

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SKAP interacts with Aurora B to guide end-on capture of spindle microtubules via phase separation

Journal of Molecular Cell Biology ◽

10.1093/jmcb/mjab058 ◽

2021 ◽

Author(s):

Manjuan Zhang ◽

Fengrui Yang ◽

Wenwen Wang ◽

Xiwei Wang ◽

Dongmei Wang ◽

...

Keyword(s):

Phase Separation ◽

Chromosome Segregation ◽

Aurora B ◽

Spindle Microtubule ◽

Dynamic Interactions ◽

Chromosome Alignment ◽

Spindle Microtubules ◽

And Behavior

Abstract Chromosome segregation in mitosis is orchestrated by the dynamic interactions between the kinetochore and spindle microtubules. Our recent studies show that mitotic motor CENP-E cooperates with SKAP and forms a link between kinetochore core MIS13 complex and spindle microtubule plus-ends to achieve accurate chromosome alignment in mitosis. However, it remains elusive how SKAP regulates kinetochore attachment from lateral association to end-on attachment during metaphase alignment. Here, we identify a novel interaction between Aurora B and SKAP that orchestrates accurate interaction between the kinetochore and dynamic spindle microtubules. Interestingly, SKAP spontaneously phase-separates in vitro via weak, multivalent interactions into droplets with fast internal dynamics. SKAP and Aurora B form heterogeneous coacervates in vitro, which recapitulate the dynamics and behavior of SKAP comets in vivo. Importantly, SKAP interaction with Aurora B via phase separation is essential for accurate chromosome segregation and alignment. Based on those findings, we reason that SKAP–Aurora B interaction via phase separation constitutes a dynamic pool of Aurora B activity during the lateral to end-on conversion of kinetochore–microtubule attachments to achieve faithful cell division.

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

The Journal of Cell Biology ◽

10.1083/jcb.201006129 ◽

2010 ◽

Vol 191 (2) ◽

pp. 269-280 ◽

Cited By ~ 80

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.

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