scholarly journals Role of ubiquitylation of components of mitotic checkpoint complex in their dissociation from anaphase-promoting complex/cyclosome

2018 ◽  
Vol 115 (8) ◽  
pp. 1777-1782 ◽  
Author(s):  
Danielle Sitry-Shevah ◽  
Sharon Kaisari ◽  
Adar Teichner ◽  
Shirly Miniowitz-Shemtov ◽  
Avram Hershko
Keyword(s):  
Chromosome Segregation ◽  
Ubiquitin Ligase ◽  
Mitotic Spindle ◽  
Mitotic Checkpoint ◽  
Terminal Region ◽  
Anaphase Promoting Complex ◽  
Lysine Residues ◽  
Mitotic Checkpoint Complex

The mitotic checkpoint system ensures the fidelity of chromosome segregation in mitosis by preventing premature initiation of anaphase until correct bipolar attachment of chromosomes to the mitotic spindle is reached. It promotes the assembly of a mitotic checkpoint complex (MCC), composed of BubR1, Bub3, Cdc20, and Mad2, which inhibits the activity of the anaphase-promoting complex/cyclosome (APC/C) ubiquitin ligase. When the checkpoint is satisfied, anaphase is initiated by the disassembly of MCC. Previous studies indicated that the dissociation of APC/C-bound MCC requires ubiquitylation and suggested that the target of ubiquitylation is the Cdc20 component of MCC. However, it remained unknown how ubiquitylation causes the release of MCC from APC/C and its disassembly and whether ubiquitylation of additional proteins is involved in this process. We find that ubiquitylation causes the dissociation of BubR1 from Cdc20 in MCC and suggest that this may lead to the release of MCC components from APC/C. BubR1 in MCC is ubiquitylated by APC/C, although to a lesser degree than Cdc20. The extent of BubR1 ubiquitylation was markedly increased in recombinant MCC that contained a lysine-less mutant of Cdc20. Mutation of lysine residues to arginines in the N-terminal region of BubR1 partially inhibited its ubiquitylation and slowed down the release of MCC from APC/C, provided that Cdc20 ubiquitylation was also blocked. It is suggested that ubiquitylation of both Cdc20 and BubR1 may be involved in their dissociation from each other and in the release of MCC components from APC/C.

scholarly journals Role of Polo-like kinase 1 in the regulation of the action of p31comet in the disassembly of mitotic checkpoint complexes

2019 ◽  
pp. 201902970 ◽  
Author(s):  
Sharon Kaisari ◽  
Pnina Shomer ◽  
Tamar Ziv ◽  
Danielle Sitry-Shevah ◽  
Shirly Miniowitz-Shemtov ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Hela Cells ◽  
Mitotic Spindle ◽  
Joint Action ◽  
Mitotic Checkpoint ◽  
Anaphase Promoting Complex ◽  
Futile Cycle ◽  
Mitotic Checkpoint Complex ◽  
Bi 2536

The Mad2-binding protein p31comet has important roles in the inactivation of the mitotic checkpoint system, which delays anaphase until chromosomes attach correctly to the mitotic spindle. The activation of the checkpoint promotes the assembly of a Mitotic Checkpoint Complex (MCC), which inhibits the action of the ubiquitin ligase APC/C (Anaphase-Promoting Complex/Cyclosome) to degrade inhibitors of anaphase initiation. The inactivation of the mitotic checkpoint requires the disassembly of MCC. p31comet promotes the disassembly of mitotic checkpoint complexes by liberating their Mad2 component in a joint action with the ATPase TRIP13. Here, we investigated the regulation of p31comet action. The release of Mad2 from checkpoint complexes in extracts from nocodazole-arrested HeLa cells was inhibited by Polo-like kinase 1 (Plk1), as suggested by the effects of selective inhibitors of Plk1. Purified Plk1 bound to p31comet and phosphorylated it, resulting in the suppression of its activity (with TRIP13) to disassemble checkpoint complexes. Plk1 phosphorylated p31comet on S102, as suggested by the prevention of the phosphorylation of this residue in checkpoint extracts by the selective Plk1 inhibitor BI-2536 and by the phosphorylation of S102 with purified Plk1. An S102A mutant of p31comet had a greatly decreased sensitivity to inhibition by Plk1 of its action to disassemble mitotic checkpoint complexes. We propose that the phosphorylation of p31comet by Plk1 prevents a futile cycle of MCC assembly and disassembly during the active mitotic checkpoint.

scholarly journals Intermediates in the assembly of mitotic checkpoint complexes and their role in the regulation of the anaphase-promoting complex

2016 ◽  
Vol 113 (4) ◽  
pp. 966-971 ◽  
Author(s):  
Sharon Kaisari ◽  
Danielle Sitry-Shevah ◽  
Shirly Miniowitz-Shemtov ◽  
Avram Hershko
Keyword(s):  
Chromosome Segregation ◽  
Mitotic Spindle ◽  
Spindle Assembly Checkpoint ◽  
Mitotic Checkpoint ◽  
Anaphase Promoting Complex ◽  
Checkpoint Proteins ◽  
Sister Chromatids ◽  
Unknown Species ◽  
Mitotic Checkpoint Complex

The mitotic (or spindle assembly) checkpoint system prevents premature separation of sister chromatids in mitosis and thus ensures the fidelity of chromosome segregation. Kinetochores that are not attached properly to the mitotic spindle produce an inhibitory signal that prevents progression into anaphase. The checkpoint system acts on the Anaphase-Promoting Complex/Cyclosome (APC/C) ubiquitin ligase, which targets for degradation inhibitors of anaphase initiation. APC/C is inhibited by the Mitotic Checkpoint Complex (MCC), which assembles when the checkpoint is activated. MCC is composed of the checkpoint proteins BubR1, Bub3, and Mad2, associated with the APC/C coactivator Cdc20. The intermediary processes in the assembly of MCC are not sufficiently understood. It is also not clear whether or not some subcomplexes of MCC inhibit the APC/C and whether Mad2 is required only for MCC assembly and not for its action on the APC/C. We used purified subcomplexes of mitotic checkpoint proteins to examine these problems. Our results do not support a model in which Mad2 catalytically generates a Mad2-free APC/C inhibitor. We also found that the release of Mad2 from MCC caused a marked (although not complete) decrease in inhibitory action, suggesting a role of Mad2 in MCC for APC/C inhibition. A previously unknown species of MCC, which consists of Mad2, BubR1, and two molecules of Cdc20, contributes to the inhibition of APC/C by the mitotic checkpoint system.

scholarly journals Mechanism of APC/CCDC20 activation by mitotic phosphorylation

2016 ◽  
Vol 113 (19) ◽  
pp. E2570-E2578 ◽  
Author(s):  
Renping Qiao ◽  
Florian Weissmann ◽  
Masaya Yamaguchi ◽  
Nicholas G. Brown ◽  
Ryan VanderLinden ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Mitotic Checkpoint ◽  
Anaphase Promoting Complex ◽  
Loop Region ◽  
Evolutionarily Conserved ◽  
Terminal Loop ◽  
Different Types ◽  
Mitotic Phosphorylation ◽  
Mitotic Checkpoint Complex

Chromosome segregation and mitotic exit are initiated by the 1.2-MDa ubiquitin ligase APC/C (anaphase-promoting complex/cyclosome) and its coactivator CDC20 (cell division cycle 20). To avoid chromosome missegregation, APC/CCDC20 activation is tightly controlled. CDC20 only associates with APC/C in mitosis when APC/C has become phosphorylated and is further inhibited by a mitotic checkpoint complex until all chromosomes are bioriented on the spindle. APC/C contains 14 different types of subunits, most of which are phosphorylated in mitosis on multiple sites. However, it is unknown which of these phospho-sites enable APC/CCDC20 activation and by which mechanism. Here we have identified 68 evolutionarily conserved mitotic phospho-sites on human APC/C bound to CDC20 and have used the biGBac technique to generate 47 APC/C mutants in which either all 68 sites or subsets of them were replaced by nonphosphorylatable or phospho-mimicking residues. The characterization of these complexes in substrate ubiquitination and degradation assays indicates that phosphorylation of an N-terminal loop region in APC1 is sufficient for binding and activation of APC/C by CDC20. Deletion of the N-terminal APC1 loop enables APC/CCDC20 activation in the absence of mitotic phosphorylation or phospho-mimicking mutations. These results indicate that binding of CDC20 to APC/C is normally prevented by an autoinhibitory loop in APC1 and that its mitotic phosphorylation relieves this inhibition. The predicted location of the N-terminal APC1 loop implies that this loop controls interactions between the N-terminal domain of CDC20 and APC1 and APC8. These results reveal how APC/C phosphorylation enables CDC20 to bind and activate the APC/C in mitosis.

scholarly journals Defining pathways of spindle checkpoint silencing: functional redundancy between Cdc20 ubiquitination and p31comet

2011 ◽  
Vol 22 (22) ◽  
pp. 4227-4235 ◽  
Author(s):  
Luying Jia ◽  
Bing Li ◽  
Ross T. Warrington ◽  
Xing Hao ◽  
Shixuan Wang ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Spindle Checkpoint ◽  
Functional Redundancy ◽  
Mitotic Checkpoint ◽  
Human Cells ◽  
Unresolved Issue ◽  
Anaphase Promoting Complex ◽  
Anaphase Onset ◽  
Mitotic Checkpoint Complex

The spindle checkpoint senses unattached or improperly attached kinetochores during mitosis, inhibits the anaphase-promoting complex or cyclosome (APC/C), and delays anaphase onset to prevent aneuploidy. The mitotic checkpoint complex (MCC) consisting of BubR1, Bub3, Mad2, and Cdc20 is a critical APC/C-inhibitory checkpoint complex in human cells. At the metaphase–anaphase transition, the spindle checkpoint turns off, and MCC disassembles to allow anaphase onset. The molecular mechanisms of checkpoint inactivation are poorly understood. A major unresolved issue is the role of Cdc20 autoubiquitination in this process. Although Cdc20 autoubiquitination can promote Mad2 dissociation from Cdc20, a nonubiquitinatable Cdc20 mutant still dissociates from Mad2 during checkpoint inactivation. Here, we show that depletion of p31comet delays Mad2 dissociation from Cdc20 mutants that cannot undergo autoubiquitination. Thus both p31comet and ubiquitination of Cdc20 are critical mechanisms of checkpoint inactivation. They act redundantly to promote Mad2 dissociation from Cdc20.

scholarly journals Mad2, Bub3, and Mps1 regulate chromosome segregation and mitotic synchrony in Giardia intestinalis, a binucleate protist lacking an anaphase-promoting complex

2014 ◽  
Vol 25 (18) ◽  
pp. 2774-2787 ◽  
Author(s):  
Juan-Jesus Vicente ◽  
W. Zacheus Cande
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
Mitotic Checkpoint ◽  
Giardia Intestinalis ◽  
Anaphase Promoting Complex ◽  
Critical Importance ◽  
Minimal Set ◽  
Left Hand ◽  
Mitotic Checkpoint Complex ◽  
Mitotic Synchrony

The binucleate pathogen Giardia intestinalis is a highly divergent eukaryote with a semiopen mitosis, lacking an anaphase-promoting complex/cyclosome (APC/C) and many of the mitotic checkpoint complex (MCC) proteins. However, Giardia has some MCC components (Bub3, Mad2, and Mps1) and proteins from the cohesin system (Smc1 and Smc3). Mad2 localizes to the cytoplasm, but Bub3 and Mps1 are either located on chromosomes or in the cytoplasm, depending on the cell cycle stage. Depletion of Bub3, Mad2, or Mps1 resulted in a lowered mitotic index, errors in chromosome segregation (including lagging chromosomes), and abnormalities in spindle morphology. During interphase, MCC knockdown cells have an abnormal number of nuclei, either one nucleus usually on the left-hand side of the cell or two nuclei with one mislocalized. These results suggest that the minimal set of MCC proteins in Giardia play a major role in regulating many aspects of mitosis, including chromosome segregation, coordination of mitosis between the two nuclei, and subsequent nuclear positioning. The critical importance of MCC proteins in an organism that lacks their canonical target, the APC/C, suggests a broader role for these proteins and hints at new pathways to be discovered.

scholarly journals Bub1 is not required for the checkpoint response to unattached kinetochores in diploid human cells

2018 ◽  
Author(s):  
Cerys E. Currie ◽  
Mar Mora-Santos ◽  
Chris Smith ◽  
Andrew D. McAinsh ◽  
Jonathan B.A. Millar
Keyword(s):  
Chromosome Segregation ◽  
Spindle Assembly Checkpoint ◽  
Mitotic Checkpoint ◽  
Human Cells ◽  
Anaphase Promoting Complex ◽  
Pathway Model ◽  
Checkpoint Response ◽  
Conflicting Evidence ◽  
Dual Pathway ◽  
Mitotic Checkpoint Complex

AbstractError-free chromosome segregation during mitosis depends on a functional spindle assembly checkpoint (SAC). The SAC is a multi-component signaling system that is recruited to incorrectly attached kinetochores to catalyze the formation of a soluble inhibitor, known as the mitotic checkpoint complex (MCC), which binds and inhibits the anaphase promoting complex [1]. We have previously proposed that two separable pathways, composed of KNL1-Bub3-Bub1 (KBB) and Rod-Zwilch-Zw10 (RZZ), recruit Mad1-Mad2 complexes to human kinetochores to activate the SAC [2]. We refer to this as the dual pathway model. Although Bub1 is absolutely required for MCC formation in yeast (which lack RZZ), there is conflicting evidence as to whether this is also the case in human cells based on siRNA studies [2–5]. Here we report, using genome editing, that Bub1 is not strictly required for the SAC response to unattached kinetochores in human diploid hTERT-RPE1 cells, consistent with the dual pathway model.

scholarly journals “Wait anaphase” signals are not confined to the mitotic spindle

2017 ◽  
Vol 28 (9) ◽  
pp. 1186-1194 ◽  
Author(s):  
Lydia R. Heasley ◽  
Steven M. Markus ◽  
Jennifer G. DeLuca
Keyword(s):  
Mitotic Spindle ◽  
Spindle Assembly Checkpoint ◽  
Mitotic Checkpoint ◽  
Anaphase Promoting Complex ◽  
Mitotic Progression ◽  
Close Proximity ◽  
A Cell ◽  
Spindle Microtubules ◽  
Mitotic Checkpoint Complex ◽  
Fusion Approach

The spindle assembly checkpoint ensures the faithful inheritance of chromosomes by arresting mitotic progression in the presence of kinetochores that are not attached to spindle microtubules. This is achieved through inhibition of the anaphase-promoting complex/cyclosome by a kinetochore-derived “wait anaphase” signal known as the mitotic checkpoint complex. It remains unclear whether the localization and activity of these inhibitory complexes are restricted to the mitotic spindle compartment or are diffusible throughout the cytoplasm. Here we report that “wait anaphase” signals are indeed able to diffuse outside the confines of the mitotic spindle compartment. Using a cell fusion approach to generate multinucleate cells, we investigate the effects of checkpoint signals derived from one spindle compartment on a neighboring spindle compartment. We find that spindle compartments in close proximity wait for one another to align all chromosomes before entering anaphase synchronously. Synchrony is disrupted in cells with increased interspindle distances and cellular constrictions between spindle compartments. In addition, when mitotic cells are fused with interphase cells, “wait anaphase” signals are diluted, resulting in premature mitotic exit. Overall our studies reveal that anaphase inhibitors are diffusible and active outside the confines of the mitotic spindle from which they are derived.

scholarly journals Role of CCT chaperonin in the disassembly of mitotic checkpoint complexes

2017 ◽  
Vol 114 (5) ◽  
pp. 956-961 ◽  
Author(s):  
Sharon Kaisari ◽  
Danielle Sitry-Shevah ◽  
Shirly Miniowitz-Shemtov ◽  
Adar Teichner ◽  
Avram Hershko
Keyword(s):  
Mitotic Checkpoint ◽  
Biologically Active ◽  
Anaphase Promoting Complex ◽  
Checkpoint Proteins ◽  
Aaa Atpase ◽  
Sister Chromatids ◽  
Ring Complex ◽  
Combined Action ◽  
Mitotic Checkpoint Complex

The mitotic checkpoint system prevents premature separation of sister chromatids in mitosis and thus ensures the fidelity of chromosome segregation. When this checkpoint is active, a mitotic checkpoint complex (MCC), composed of the checkpoint proteins Mad2, BubR1, Bub3, and Cdc20, is assembled. MCC inhibits the ubiquitin ligase anaphase promoting complex/cyclosome (APC/C), whose action is necessary for anaphase initiation. When the checkpoint signal is turned off, MCC is disassembled, a process required for exit from checkpoint-arrested state. Different moieties of MCC are disassembled by different ATP-requiring processes. Previous work showed that Mad2 is released from MCC by the joint action of the TRIP13 AAA-ATPase and the Mad2-binding protein p31comet. Now we have isolated from extracts of HeLa cells an ATP-dependent factor that releases Cdc20 from MCC and identified it as chaperonin containing TCP1 or TCP1–Ring complex (CCT/TRiC chaperonin), a complex known to function in protein folding. Bacterially expressed CCT5 chaperonin subunits, which form biologically active homooligomers [Sergeeva, et al. (2013)J Biol Chem288(24):17734–17744], also promote the disassembly of MCC. CCT chaperonin further binds and disassembles subcomplexes of MCC that lack Mad2. Thus, the combined action of CCT chaperonin with that of TRIP13 ATPase promotes the complete disassembly of MCC, necessary for the inactivation of the mitotic checkpoint.

scholarly journals The Role of Anaphase-Promoting Complex/Cyclosome (APC/C) in Plant Reproduction

2021 ◽  
Vol 12 ◽  
Author(s):  
Marina de Lyra Soriano Saleme ◽  
Ingrid Rocha Andrade ◽  
Nubia Barbosa Eloy
Keyword(s):  
Chromosome Segregation ◽  
Ubiquitin Ligase ◽  
Male Gametophyte ◽  
Functional Characterization ◽  
E3 Ubiquitin Ligase ◽  
Embryo Sac ◽  
Anaphase Promoting Complex ◽  
Ploidy Stability ◽  
Embryo Sac Formation

Most eukaryotic species propagate through sexual reproduction that requires male and female gametes. In flowering plants, it starts through a single round of DNA replication (S phase) and two consecutive chromosome segregation (meiosis I and II). Subsequently, haploid mitotic divisions occur, which results in a male gametophyte (pollen grain) and a female gametophyte (embryo sac) formation. In order to obtain viable gametophytes, accurate chromosome segregation is crucial to ensure ploidy stability. A precise gametogenesis progression is tightly regulated in plants and is controlled by multiple mechanisms to guarantee a correct evolution through meiotic cell division and sexual differentiation. In the past years, research in the field has shown an important role of the conserved E3-ubiquitin ligase complex, Anaphase-Promoting Complex/Cyclosome (APC/C), in this process. The APC/C is a multi-subunit complex that targets proteins for degradation via proteasome 26S. The functional characterization of APC/C subunits in Arabidopsis, which is one of the main E3 ubiquitin ligase that controls cell cycle, has revealed that all subunits investigated so far are essential for gametophytic development and/or embryogenesis.

scholarly journals Mode of interaction of TRIP13 AAA-ATPase with the Mad2-binding protein p31comet and with mitotic checkpoint complexes

2015 ◽  
Vol 112 (37) ◽  
pp. 11536-11540 ◽  
Author(s):  
Shirly Miniowitz-Shemtov ◽  
Ety Eytan ◽  
Sharon Kaisari ◽  
Danielle Sitry-Shevah ◽  
Avram Hershko
Keyword(s):  
Mitotic Spindle ◽  
Spindle Assembly Checkpoint ◽  
Thyroid Hormone Receptor ◽  
Binding Protein ◽  
Mitotic Checkpoint ◽  
Anaphase Promoting Complex ◽  
Interacting Protein ◽  
Aaa Atpase ◽  
Oligomeric Form ◽  
Mitotic Checkpoint Complex

The AAA-ATPase thyroid hormone receptor interacting protein 13 (TRIP13), jointly with the Mad2-binding protein p31comet, promotes the inactivation of the mitotic (spindle assembly) checkpoint by disassembling the mitotic checkpoint complex (MCC). This checkpoint system ensures the accuracy of chromosome segregation by delaying anaphase until correct bipolar attachment of chromatids to the mitotic spindle is achieved. MCC inhibits the anaphase-promoting complex/cyclosome (APC/C), a ubiquitin ligase that targets for degradation securin, an inhibitor of anaphase initiation. MCC is composed of the checkpoint proteins Mad2, BubR1, and Bub3, in association with the APC/C activator Cdc20. The assembly of MCC in active checkpoint is initiated by the conversion of Mad2 from an open (O-Mad2) to a closed (C-Mad2) conformation, which then binds tightly to Cdc20. Conversely, the disassembly of MCC that takes place when the checkpoint is turned off involves the conversion of C-Mad2 back to O-Mad2. Previously, we found that the latter process is mediated by TRIP13 together with p31comet, but the mode of their interaction remained unknown. Here, we report that the oligomeric form of TRIP13 binds both p31comet and MCC. Furthermore, p31comet and checkpoint complexes mutually promote the binding of each other to oligomeric TRIP13. We propose that p31comet bound to C-Mad2–containing checkpoint complex is the substrate for the ATPase and that the substrate-binding site of TRIP13 is composed of subsites specific for p31comet and C-Mad2–containing complex. The simultaneous occupancy of both subsites is required for high-affinity binding to TRIP13.

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