Mutations in TED1 and DCR2, two glycosylphosphatidylinositol anchored protein remodelases, activate the spindle assembly checkpoint in budding yeast cells

2017 ◽  
Author(s):  
Li Chen
Keyword(s):  
Spindle Assembly Checkpoint ◽  
Budding Yeast ◽  
Spindle Assembly ◽  
Yeast Cells

scholarly journals Multiple mechanisms determine the order of APC/C substrate degradation in mitosis

2014 ◽  
Vol 207 (1) ◽  
pp. 23-39 ◽  
Author(s):  
Dan Lu ◽  
Jennifer Y. Hsiao ◽  
Norman E. Davey ◽  
Vanessa A. Van Voorhis ◽  
Scott A. Foster ◽  
...  
Keyword(s):  
Fluorescence Microscopy ◽  
Binding Sites ◽  
Spindle Assembly Checkpoint ◽  
Budding Yeast ◽  
Spindle Assembly ◽  
Yeast Cells ◽  
Anaphase Promoting Complex ◽  
Ubiquitin Protein Ligase ◽  
Substrate Degradation ◽  
Quantitative Fluorescence

The ubiquitin protein ligase anaphase-promoting complex or cyclosome (APC/C) controls mitosis by promoting ordered degradation of securin, cyclins, and other proteins. The mechanisms underlying the timing of APC/C substrate degradation are poorly understood. We explored these mechanisms using quantitative fluorescence microscopy of GFP-tagged APC/CCdc20 substrates in living budding yeast cells. Degradation of the S cyclin, Clb5, begins early in mitosis, followed 6 min later by the degradation of securin and Dbf4. Anaphase begins when less than half of securin is degraded. The spindle assembly checkpoint delays the onset of Clb5 degradation but does not influence securin degradation. Early Clb5 degradation depends on its interaction with the Cdk1–Cks1 complex and the presence of a Cdc20-binding “ABBA motif” in its N-terminal region. The degradation of securin and Dbf4 is delayed by Cdk1-dependent phosphorylation near their Cdc20-binding sites. Thus, a remarkably diverse array of mechanisms generates robust ordering of APC/CCdc20 substrate destruction.

scholarly journals Disruption of Astral Microtubule Contact with the Cell Cortex Activates a Bub1, Bub3, and Mad3-dependent Checkpoint in Fission Yeast

2004 ◽  
Vol 15 (7) ◽  
pp. 3345-3356 ◽  
Author(s):  
Sylvie Tournier ◽  
Yannick Gachet ◽  
Vicky Buck ◽  
Jeremy S. Hyams ◽  
Jonathan B.A. Millar
Keyword(s):  
Actin Cytoskeleton ◽  
Fission Yeast ◽  
Spindle Assembly Checkpoint ◽  
Spindle Assembly ◽  
Yeast Cells ◽  
Cell Cortex ◽  
Checkpoint Proteins ◽  
Sister Chromatids ◽  
Astral Microtubule ◽  
Spindle Rotation

In animal and yeast cells, the mitotic spindle is aligned perpendicularly to the axis of cell division. This ensures that sister chromatids are separated to opposite sides of the cytokinetic actomyosin ring. In fission yeast, spindle rotation is dependent upon the interaction of astral microtubules with the cortical actin cytoskeleton. In this article, we show that addition of Latrunculin A, which prevents spindle rotation, delays the separation of sister chromatids and anaphase promoting complex-mediated destruction of spindle-associated Securin and Cyclin B. Moreover, we find that whereas sister kinetochore pairs normally congress to the spindle midzone before anaphase onset, this congression is disrupted when astral microtubule contact with the actin cytoskeleton is disturbed. By analyzing the timing of kinetochore separation, we find that this anaphase delay requires the Bub3, Mad3, and Bub1 but not the Mad1 or Mad2 spindle assembly checkpoint proteins. In agreement with this, we find that Bub1 remains associated with kinetochores when spindles are mispositioned. These data indicate that, in fission yeast, astral microtubule contact with the medial cell cortex is monitored by a subset of spindle assembly checkpoint proteins. We propose that this checkpoint ensures spindles are properly oriented before anaphase takes place.

scholarly journals A stochastic model for error correction of kinetochore-microtubule attachments and its coupling to the spindle assembly checkpoint

2019 ◽  
Author(s):  
Anand Banerjee ◽  
Neil Adames ◽  
Jean Peccoud ◽  
John J. Tyson
Keyword(s):  
Stochastic Model ◽  
Error Correction ◽  
Spindle Assembly Checkpoint ◽  
Budding Yeast ◽  
Analytical Formula ◽  
Spindle Assembly ◽  
Experimental Information ◽  
Checkpoint Signaling ◽  
Balance Point ◽  
Checkpoint Signal

AbstractTo divide replicated chromosomes equally between daughter cells kinetochores must attach to microtubules emanating from opposite poles of the mitotic spindle. Two mechanisms, namely, error correction and ‘spindle assembly checkpoint’ work together to facilitate this process. The error correction mechanism recognizes and detaches erroneous kinetochore-microtubule attachments, and the spindle assembly checkpoint delays the onset of anaphase until all the kinetochores are properly attached. Kinases and phosphatases at the kinetochore play a key role in proper functioning of these two mechanisms. Here we present a stochastic model to study how the opposing activities of kinases and phosphatases at the kinetochore affect error correction of kinetochore-microtubule attachments and checkpoint signaling in budding yeast, Saccharomyces cerevisiae. We show that error correction and biorientation of chromosomes occurs efficiently when the ratio between kinase activity of Ipl1 and the activity of an opposing phosphatase is a constant (balance point), and derive an approximate analytical formula that defines the balance point. Analysis of the coupling of the spindle assembly checkpoint signal to error correction shows that its strength remains high when the Ipl1 activity is equal to (or larger than) the value specified by the balance point, and the activity of another kinase, Mps1, is much larger (approximately 30 times larger) than its opposing phosphatase (PP1). We also find that the geometrical orientation of sister chromatids does not significantly improve the probability of their reaching biorientation, which depends entirely on Ipl1-dependent microtubule detachment.Author summaryThe kinetochore, the master regulator of chromosome segregation, integrates signals from different chromosome attachment states to generate an appropriate response, like the destabilization of erroneous kinetochore-microtubule attachments, stabilization of correct attachments, maintenance of the spindle assembly checkpoint signal until all kinetochores are properly attached, and finally silencing of checkpoint when biorientation is achieved. At a molecular level the job is carried out by kinases and phosphatases. The complexity of the interactions between these kinases and phosphatases makes intuitive analysis of the control network impossible, and a systems-level model is needed to put experimental information together and to generate testable hypotheses. Here we present such a model for the process of error correction and its coupling to the spindle assembly checkpoint in budding yeast. Using the model, we characterize the balance between kinase and phosphatase activities required for removing erroneous attachments and then establishing correct stable attachments between kinetochore and microtubule. We also analyze how the balance affects the strength of the spindle assembly checkpoint signal.

scholarly journals Aberrantly segregating centromeres activate the spindle assembly checkpoint in budding yeast.

1996 ◽  
Vol 133 (1) ◽  
pp. 75-84 ◽  
Author(s):  
W A Wells ◽  
A W Murray
Keyword(s):  
Copy Number ◽  
Spindle Assembly Checkpoint ◽  
Budding Yeast ◽  
Spindle Assembly ◽  
Pedigree Analysis ◽  
Eukaryotic Cells ◽  
Gene Products ◽  
Chromosome Behavior ◽  
Daughter Cells ◽  
Chromosome Alignment

The spindle assembly checkpoint is the mechanism or set of mechanisms that prevents cells with defects in chromosome alignment or spindle assembly from passing through mitosis. We have investigated the effects of mini-chromosomes on this checkpoint in budding yeast by performing pedigree analysis. This method allowed us to observe the frequency and duration of cell cycle delays in individual cells. Short, centromeric linear mini-chromosomes, which have a low fidelity of segregation, cause frequent delays in mitosis. Their circular counterparts and longer linear mini-chromosomes, which segregate more efficiently, show a much lower frequency of mitotic delays, but these delays occur much more frequently in divisions where the mini-chromosome segregates to only one of the two daughter cells. Using a conditional centromere to increase the copy number of a circular mini-chromosome greatly increases the frequency of delayed divisions. In all cases the division delays are completely abolished by the mad mutants that inactivate the spindle assembly checkpoint, demonstrating that the Mad gene products are required to detect the subtle defects in chromosome behavior that have been observed to arrest higher eukaryotic cells in mitosis.

Activation of the Budding Yeast Spindle Assembly Checkpoint Without Mitotic Spindle Disruption

Science ◽  
1996 ◽  
Vol 273 (5277) ◽  
pp. 953-956 ◽  
Author(s):  
K. G. Hardwick ◽  
E. Weiss ◽  
F. C. Luca ◽  
M. Winey ◽  
A. W. Murray
Keyword(s):  
Mitotic Spindle ◽  
Spindle Assembly Checkpoint ◽  
Budding Yeast ◽  
Spindle Assembly

scholarly journals Histone H3 Exerts a Key Function in Mitotic Checkpoint Control

2009 ◽  
Vol 30 (2) ◽  
pp. 537-549 ◽  
Author(s):  
Jianjun Luo ◽  
Xinjing Xu ◽  
Hana Hall ◽  
Edel M. Hyland ◽  
Jef D. Boeke ◽  
...  
Keyword(s):  
Spindle Assembly Checkpoint ◽  
Histone H3 ◽  
Spindle Assembly ◽  
Mitotic Checkpoint ◽  
Spindle Pole ◽  
Yeast Cells ◽  
Checkpoint Control ◽  
Spindle Pole Bodies ◽  
Key Factor ◽  
Pulling Force

ABSTRACT It has been firmly established that many interphase nuclear functions, including transcriptional regulation, are regulated by chromatin and histones. How mitotic progression and quality control might be influenced by histones is less well characterized. We show that histone H3 plays a crucial role in activating the spindle assembly checkpoint in response to a defect in mitosis. Prior to anaphase, all chromosomes must attach to spindles emanating from the opposite spindle pole bodies. The tension between sister chromatids generated by the poleward pulling force is an integral part of chromosome biorientation. Lack of tension due to erroneous attachment activates the spindle assembly checkpoint, which corrects the mistakes and ensures segregation fidelity. A histone H3 mutation impairs the ability of yeast cells to activate the checkpoint in a tensionless crisis, leading to missegregation and aneuploidy. The defects in tension sensing result directly from an attenuated H3-Sgo1p interaction essential for pericentric recruitment of Sgo1p. Reinstating the pericentric enrichment of Sgo1p alleviates the mitotic defects. Histone H3, and hence the chromatin, is thus a key factor transmitting the tension status to the spindle assembly checkpoint.

scholarly journals Phospho-regulation of the Shugoshin - Condensin interaction at the centromere in budding yeast

2019 ◽  
Author(s):  
Galal Yahya Metwaly ◽  
Yehui Wu ◽  
Karolina Peplowska ◽  
Jennifer Röhrl ◽  
Young-Min Soh ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Protein Phosphatase ◽  
Spindle Assembly Checkpoint ◽  
Budding Yeast ◽  
Spindle Assembly ◽  
Mass Spectrometry Analysis ◽  
Spectrometry Analysis ◽  
Spindle Poles ◽  
Condensin Complex ◽  
Centromeric Protein

AbstractCorrect bioriented attachment of sister chromatids to mitotic spindle is essential for chromosome segregation. The conserved protein shugoshin (Sgo1) contributes in budding yeast to biorientation by recruiting the protein phosphatase PP2A-Rts1 and the condensin complex to centromeres. Using peptide prints, we identified a Serine-Rich Motif (SRM) of Sgo1 that mediates the interaction with condensin and is essential for centromeric condensin recruitment and the establishment of biorientation. We show that the interaction is regulated via phosphorylation within the SRM and we determined the phospho-sites using mass spectrometry. Analysis of the phosphomimicking and phosphoresistant mutants revealed that SRM phosphorylation disrupts the shugoshin – condensin interaction. We present an evidence that Mps1, a central kinase in the spindle assembly checkpoint, directly phosphorylates Sgo1 within the SRM to regulate the interaction with condensin and thereby condensin localization to centromeres. Our findings identify novel mechanisms that control shugoshin activity at the centromere in budding yeast.Author summaryProper chromosome segregation in eukaryotes is ensured through correct attachment of the spindle microtubules to the centromeric chromosomal regions. The attachment is mediated via the multimolecular proteinaceous complex called kinetochore and precisely regulated. This enables the establishment of so called bioirentation, when each sister chromatid is attached to microtubules emanating from opposite spindle poles. Shugoshin (Sgo1) is a conserved centromeric protein that facilitates biorientation through its interactions with the protein phosphatase PP2A/Rts1, chromosome passanger complex and centromeric condensin. Here, we identified a serin-rich motif that is required for the interaction of shugoshin with the condensin complex. We show that loss of this region impairs condensin enrichment at the centromere, chromosome biorientation, segregation as well as the function of the chromosome passanger complex in the error correction. Moreover, the interaction is phosphoregulated, as phosphorylation of the serin-rich motif on Sgo1 disrupts its interaction with condensin. Finally, we show that the conserved spindle assembly checkpoint kinase Mps1 is responsible for this phosphorylation. Our findings uncover novel regulatory mechanisms that facilitate proper chromosome segregation.

scholarly journals Abnormal kinetochore structure activates the spindle assembly checkpoint in budding yeast.

1996 ◽  
Vol 7 (8) ◽  
pp. 1195-1208 ◽  
Author(s):  
F Pangilinan ◽  
F Spencer
Keyword(s):  
Spindle Assembly Checkpoint ◽  
Budding Yeast ◽  
Spindle Assembly ◽  
Single Copy ◽  
Animal Cells ◽  
Drug Induced ◽  
Kinetochore Protein ◽  
Dna Mutation ◽  
Chromosome Attachment ◽  
Limited Function

Saccharomyces cerevisiae cells containing one or more abnormal kinetochores delay anaphase entry. The delay can be produced by using centromere DNA mutations present in single-copy or kinetochore protein mutations. This observation is strikingly similar to the preanaphase delay or arrest exhibited in animal cells that experience spontaneous or induced failures in bipolar attachment of one or more chromosomes and may reveal the existence of a conserved surveillance pathway that monitors the state of chromosome attachment to the spindle before anaphase. We find that three genes (MAD2, BUB1, and BUB2) that are required for the spindle assembly checkpoint in budding yeast (defined by antimicrotubule drug-induced arrest or delay) are also required in the establishment and/or maintenance of kinetochore-induced delays. This was tested in strains in which the delays were generated by limited function of a mutant kinetochore protein (ctf13-30) or by the presence of a single-copy centromere DNA mutation (CDEII delta 31). Whereas the MAD2 and BUB1 genes were absolutely required for delay, loss of BUB2 function resulted in a partial delay defect, and we suggest that BUB2 is required for delay maintenance. The inability of mad2-1 and bub1 delta mutants to execute kinetochore-induced delay is correlated with striking increases in chromosome missegregation, indicating that the delay does indeed have a role in chromosome transmission fidelity. Our results also indicated that the yeast RAD9 gene, necessary for DNA damage-induced arrest, had no role in the kinetochore-induced delays. We conclude that abnormal kinetochore structures induce preanaphase delay by activating the same functions that have defined the spindle assembly checkpoint in budding yeast.

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