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 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 The small molecule Hesperadin reveals a role for Aurora B in correcting kinetochore–microtubule attachment and in maintaining the spindle assembly checkpoint

2003 ◽  
Vol 161 (2) ◽  
pp. 281-294 ◽  
Author(s):  
Silke Hauf ◽  
Richard W. Cole ◽  
Sabrina LaTerra ◽  
Christine Zimmer ◽  
Gisela Schnapp ◽  
...  
Keyword(s):  
Small Molecule ◽  
Mammalian Cells ◽  
Spindle Assembly Checkpoint ◽  
Spindle Pole ◽  
Aurora B ◽  
Checkpoint Signaling ◽  
Mitotic Kinase ◽  
Microtubule Attachment ◽  
Sister Chromatids ◽  
Chromosome Alignment

The proper segregation of sister chromatids in mitosis depends on bipolar attachment of all chromosomes to the mitotic spindle. We have identified the small molecule Hesperadin as an inhibitor of chromosome alignment and segregation. Our data imply that Hesperadin causes this phenotype by inhibiting the function of the mitotic kinase Aurora B. Mammalian cells treated with Hesperadin enter anaphase in the presence of numerous monooriented chromosomes, many of which may have both sister kinetochores attached to one spindle pole (syntelic attachment). Hesperadin also causes cells arrested by taxol or monastrol to enter anaphase within <1 h, whereas cells in nocodazole stay arrested for 3–5 h. Together, our data suggest that Aurora B is required to generate unattached kinetochores on monooriented chromosomes, which in turn could promote bipolar attachment as well as maintain checkpoint signaling.

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 Preventing farnesylation of the dynein adaptor Spindly contributes to the mitotic defects caused by farnesyltransferase inhibitors

2015 ◽  
Vol 26 (10) ◽  
pp. 1845-1856 ◽  
Author(s):  
Andrew J. Holland ◽  
Rita M. Reis ◽  
Sherry Niessen ◽  
Cláudia Pereira ◽  
Douglas A. Andres ◽  
...  
Keyword(s):  
Spindle Assembly Checkpoint ◽  
Cytoplasmic Dynein ◽  
Molecular Replacement ◽  
Farnesyltransferase Inhibitors ◽  
Checkpoint Signaling ◽  
Cellular Processes ◽  
Chromosome Congression ◽  
Mitotic Abnormalities ◽  
Clinical Interest ◽  
Insight Into

The clinical interest in farnesyltransferase inhibitors (FTIs) makes it important to understand how these compounds affect cellular processes involving farnesylated proteins. Mitotic abnormalities observed after treatment with FTIs have so far been attributed to defects in the farnesylation of the outer kinetochore proteins CENP-E and CENP-F, which are involved in chromosome congression and spindle assembly checkpoint signaling. Here we identify the cytoplasmic dynein adaptor Spindly as an additional component of the outer kinetochore that is modified by farnesyltransferase (FTase). We show that farnesylation of Spindly is essential for its localization, and thus for the proper localization of dynein and its cofactor dynactin, to prometaphase kinetochores and that Spindly kinetochore recruitment is more severely affected by FTase inhibition than kinetochore recruitment of CENP-E and CENP-F. Molecular replacement experiments show that both Spindly and CENP-E farnesylation are required for efficient chromosome congression. The identification of Spindly as a new mitotic substrate of FTase provides insight into the causes of the mitotic phenotypes observed with FTase inhibitors.

scholarly journals Kinetochore-localized BUB-1/BUB-3 complex promotes anaphase onset in C. elegans

2015 ◽  
Vol 209 (4) ◽  
pp. 507-517 ◽  
Author(s):  
Taekyung Kim ◽  
Mark W. Moyle ◽  
Pablo Lara-Gonzalez ◽  
Christian De Groot ◽  
Karen Oegema ◽  
...  
Keyword(s):  
Spindle Checkpoint ◽  
Kinase Domain ◽  
Mitotic Chromosomes ◽  
Checkpoint Signaling ◽  
C Elegans ◽  
Anaphase Onset ◽  
Checkpoint Pathway ◽  
Chromosome Alignment ◽  
Kinetochore Region

The conserved Bub1/Bub3 complex is recruited to the kinetochore region of mitotic chromosomes, where it initiates spindle checkpoint signaling and promotes chromosome alignment. Here we show that, in contrast to the expectation for a checkpoint pathway component, the BUB-1/BUB-3 complex promotes timely anaphase onset in Caenorhabditis elegans embryos. This activity of BUB-1/BUB-3 was independent of spindle checkpoint signaling but required kinetochore localization. BUB-1/BUB-3 inhibition equivalently delayed separase activation and other events occurring during mitotic exit. The anaphase promotion function required BUB-1’s kinase domain, but not its kinase activity, and this function was independent of the role of BUB-1/BUB-3 in chromosome alignment. These results reveal an unexpected role for the BUB-1/BUB-3 complex in promoting anaphase onset that is distinct from its well-studied functions in checkpoint signaling and chromosome alignment, and suggest a new mechanism contributing to the coordination of the metaphase-to-anaphase transition.

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 the Ndc80 complex protein, HEC1, by Nek2 kinase modulates chromosome alignment and signaling of the spindle assembly checkpoint

2011 ◽  
Vol 22 (19) ◽  
pp. 3584-3594 ◽  
Author(s):  
Randy Wei ◽  
Bryan Ngo ◽  
Guikai Wu ◽  
Wen-Hwa Lee
Keyword(s):  
Cell Death ◽  
Rna Interference ◽  
Molecular Mechanism ◽  
Chromosome Segregation ◽  
Spindle Assembly Checkpoint ◽  
Distribution Characteristic ◽  
Checkpoint Signaling ◽  
Chromosome Alignment ◽  
Ndc80 Complex ◽  
Complex Protein

The spindle assemble checkpoint (SAC) is critical for accurate chromosome segregation. Hec1 contributes to chromosome segregation in part by mediating SAC signaling and chromosome alignment. However, the molecular mechanism by which Hec1 modulates checkpoint signaling and alignment remains poorly understood. We found that Hec1 serine 165 (S165) is preferentially phosphorylated at kinetochores. Phosphorylated Hec1 serine 165 (pS165) specifically localized to kinetochores of misaligned chromosomes, showing a spatiotemporal distribution characteristic of SAC molecules. Expressing an RNA interference (RNAi)-resistant S165A mutant in Hec1-depleted cells permitted normal progression to metaphase, but accelerated the metaphase-to-anaphase transition. The S165A cells were defective in Mad1 and Mad2 localization to kinetochores, regardless of attachment status. These cells often entered anaphase with lagging chromosomes and elicited increased segregation errors and cell death. In contrast, expressing S165E mutant in Hec1-depleted cells triggered defective chromosome alignment and severe mitotic arrest associated with increased Mad1/Mad2 signals at prometaphase kinetochores. A small portion of S165E cells eventually bypassed the SAC but showed severe segregation errors. Nek2 is the primary kinase responsible for kinetochore pS165, while PP1 phosphatase may dephosphorylate pS165 during SAC silencing. Taken together, these results suggest that modifications of Hec1 S165 serve as an important mechanism in modulating SAC signaling and chromosome alignment.

scholarly journals Modeling the temporal evolution of the spindle assembly checkpoint and role of Aurora B kinase

2008 ◽  
Vol 105 (51) ◽  
pp. 20215-20220 ◽  
Author(s):  
H. B. Mistry ◽  
D. E. MacCallum ◽  
R. C. Jackson ◽  
M. A. J. Chaplain ◽  
F. A. Davidson
Keyword(s):  
Spindle Assembly Checkpoint ◽  
Temporal Evolution ◽  
Spindle Assembly ◽  
Aurora B ◽  
Aurora B Kinase

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.

scholarly journals Knl1 participates in spindle assembly checkpoint signaling in maize

2021 ◽  
Vol 118 (20) ◽  
pp. e2022357118
Author(s):  
Handong Su ◽  
Yang Liu ◽  
Chunhui Wang ◽  
Yalin Liu ◽  
Chao Feng ◽  
...  
Keyword(s):  
Cell Division ◽  
Evolutionary History ◽  
Spindle Assembly Checkpoint ◽  
Spindle Assembly ◽  
Helical Conformation ◽  
Evolutionary Patterns ◽  
Checkpoint Signaling ◽  
Microtubule Attachment ◽  
Tpr Domain

The Knl1-Mis12-Ndc80 (KMN) network is an essential component of the kinetochore–microtubule attachment interface, which is required for genomic stability in eukaryotes. However, little is known about plant Knl1 proteins because of their complex evolutionary history. Here, we cloned the Knl1 homolog from maize (Zea mays) and confirmed it as a constitutive central kinetochore component. Functional assays demonstrated their conserved role in chromosomal congression and segregation during nuclear division, thus causing defective cell division during kernel development when Knl1 transcript was depleted. A 145 aa region in the middle of maize Knl1, that did not involve the MELT repeats, was associated with the interaction of spindle assembly checkpoint (SAC) components Bub1/Mad3 family proteins 1 and 2 (Bmf1/2) but not with the Bmf3 protein. They may form a helical conformation with a hydrophobic interface with the TPR domain of Bmf1/2, which is similar to that of vertebrates. However, this region detected in monocots shows extensive divergence in eudicots, suggesting that distinct modes of the SAC to kinetochore connection are present within plant lineages. These findings elucidate the conserved role of the KMN network in cell division and a striking dynamic of evolutionary patterns in the SAC signaling and kinetochore network.

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