scholarly journals Bub3 and Bub1 maintain the balance of kinetochore-localized Aurora B Kinase and Protein Phosphatase I to Regulate Chromosome Segregation and Anaphase Onset in Meiosis

2019 ◽  
Author(s):  
Gisela Cairo ◽  
Anne M. MacKenzie ◽  
Soni Lacefield
Keyword(s):  
Chromosome Segregation ◽  
Protein Phosphatase ◽  
Meiotic Chromosome ◽  
Protein Phosphatase 1 ◽  
Aurora B ◽  
Aurora B Kinase ◽  
Checkpoint Proteins ◽  
Anaphase Onset ◽  
Normal Duration ◽  
Spindle Microtubules

AbstractAccurate chromosome segregation depends on proper attachment of kinetochores to spindle microtubules prior to anaphase onset. The Ipl1/Aurora B kinase corrects improper attachments by phosphorylating kinetochore components and so releasing aberrant kinetochore-microtubule interactions. The localization of Ipl1 to kinetochores in budding yeast depends upon multiple pathways, including the Bub1/Bub3 pathway. We show here that in meiosis, Bub3 is crucial for correction of attachment errors. Depletion of Bub3 results in reduced levels of kinetochore-localized Ipl1, and concomitant massive chromosome mis-segregation caused by incorrect chromosome-spindle attachments. Depletion of Bub3 also results in shorter metaphase I and metaphase II due to premature localization of protein phosphatase 1 (PP1) to kinetochores, which antagonizes Ipl1-mediated phosphorylation. We propose a new role for the Bub1-Bub3 pathway in maintaining the balance between kinetochore-localization of Ipl1 and PP1, a balance that is essential for accurate meiotic chromosome segregation and timely anaphase onset.SummaryCairo et al show that in S. cerevisiae meiosis, spindle checkpoint proteins Bub1 and Bub3 have an essential role in preventing chromosome mis-segregation and setting the normal duration of anaphase I and anaphase II onset by regulating the kinetochore-localization of Ipl1 and PP1.

scholarly journals Differential requirement for Bub1 and Bub3 in regulation of meiotic versus mitotic chromosome segregation

2020 ◽  
Vol 219 (4) ◽  
Author(s):  
Gisela Cairo ◽  
Anne M. MacKenzie ◽  
Soni Lacefield
Keyword(s):  
Chromosome Segregation ◽  
Protein Phosphatase ◽  
Mitotic Chromosome ◽  
Budding Yeast ◽  
Meiotic Chromosome ◽  
Protein Phosphatase 1 ◽  
Aurora B ◽  
Chromosome Missegregation ◽  
Anaphase Onset ◽  
Spindle Microtubules

Accurate chromosome segregation depends on the proper attachment of kinetochores to spindle microtubules before anaphase onset. The Ipl1/Aurora B kinase corrects improper attachments by phosphorylating kinetochore components and so releasing aberrant kinetochore–microtubule interactions. The localization of Ipl1 to kinetochores in budding yeast depends upon multiple pathways, including the Bub1–Bub3 pathway. We show here that in meiosis, Bub3 is crucial for correction of attachment errors. Depletion of Bub3 results in reduced levels of kinetochore-localized Ipl1 and concomitant massive chromosome missegregation caused by incorrect chromosome–spindle attachments. Depletion of Bub3 also results in shorter metaphase I and metaphase II due to premature localization of protein phosphatase 1 (PP1) to kinetochores, which antagonizes Ipl1-mediated phosphorylation. We propose a new role for the Bub1–Bub3 pathway in maintaining the balance between kinetochore localization of Ipl1 and PP1, a balance that is essential for accurate meiotic chromosome segregation and timely anaphase onset.

scholarly journals Regulated targeting of protein phosphatase 1 to the outer kinetochore by KNL1 opposes Aurora B kinase

2010 ◽  
Vol 188 (6) ◽  
pp. 809-820 ◽  
Author(s):  
Dan Liu ◽  
Mathijs Vleugel ◽  
Chelsea B. Backer ◽  
Tetsuya Hori ◽  
Tatsuo Fukagawa ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Protein Phosphatase ◽  
Genomic Stability ◽  
Feedback Mechanism ◽  
Protein Phosphatase 1 ◽  
Aurora B ◽  
Aurora B Kinase ◽  
Conserved Motif ◽  
Spindle Microtubules ◽  
Positive Feedback Mechanism

Regulated interactions between kinetochores and spindle microtubules are essential to maintain genomic stability during chromosome segregation. The Aurora B kinase phosphorylates kinetochore substrates to destabilize kinetochore–microtubule interactions and eliminate incorrect attachments. These substrates must be dephosphorylated to stabilize correct attachments, but how opposing kinase and phosphatase activities are coordinated at the kinetochore is unknown. Here, we demonstrate that a conserved motif in the kinetochore protein KNL1 directly interacts with and targets protein phosphatase 1 (PP1) to the outer kinetochore. PP1 recruitment by KNL1 is required to dephosphorylate Aurora B substrates at kinetochores and stabilize microtubule attachments. PP1 levels at kinetochores are regulated and inversely proportional to local Aurora B activity. Indeed, we demonstrate that phosphorylation of KNL1 by Aurora B disrupts the KNL1–PP1 interaction. In total, our results support a positive feedback mechanism by which Aurora B activity at kinetochores not only targets substrates directly, but also prevents localization of the opposing phosphatase.

scholarly journals The Ki-67 and RepoMan mitotic phosphatases assemble via an identical, yet novel mechanism

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Ganesan Senthil Kumar ◽  
Ezgi Gokhan ◽  
Sofie De Munter ◽  
Mathieu Bollen ◽  
Paola Vagnarelli ◽  
...  
Keyword(s):  
Protein Phosphatase ◽  
Mitotic Chromosome ◽  
Cancer Therapeutics ◽  
Mitotic Exit ◽  
Protein Phosphatase 1 ◽  
Aurora B ◽  
Aurora B Kinase ◽  
Ki 67 ◽  
Anaphase Onset

Ki-67 and RepoMan have key roles during mitotic exit. Previously, we showed that Ki-67 organizes the mitotic chromosome periphery and recruits protein phosphatase 1 (PP1) to chromatin at anaphase onset, in a similar manner as RepoMan (<xref ref-type="bibr" rid="bib2">Booth et al., 2014</xref>). Here we show how Ki-67 and RepoMan form mitotic exit phosphatases by recruiting PP1, how they distinguish between distinct PP1 isoforms and how the assembly of these two holoenzymes are dynamically regulated by Aurora B kinase during mitosis. Unexpectedly, our data also reveal that Ki-67 and RepoMan bind PP1 using an identical, yet novel mechanism, interacting with a PP1 pocket that is engaged only by these two PP1 regulators. These findings not only show how two distinct mitotic exit phosphatases are recruited to their substrates, but also provide immediate opportunities for the design of novel cancer therapeutics that selectively target the Ki-67:PP1 and RepoMan:PP1 holoenzymes.

scholarly journals Yeast Fin1-PP1 dephosphorylates an Ipl1 substrate, Ndc80, to remove Bub1-Bub3 checkpoint proteins from the kinetochore during anaphase

PLoS Genetics ◽  
2021 ◽  
Vol 17 (5) ◽  
pp. e1009592
Author(s):  
Michael Bokros ◽  
Delaney Sherwin ◽  
Marie-Helene Kabbaj ◽  
Yanchang Wang
Keyword(s):  
Chromosome Segregation ◽  
Protein Phosphatase ◽  
Spindle Assembly Checkpoint ◽  
Kinase Activity ◽  
Protein Phosphatase 1 ◽  
Regulatory Subunit ◽  
Cyclin Dependent Kinase ◽  
Checkpoint Proteins ◽  
Anaphase Onset ◽  
Chromosome Attachment

The spindle assembly checkpoint (SAC) prevents anaphase onset in response to chromosome attachment defects, and SAC silencing is essential for anaphase onset. Following anaphase onset, activated Cdc14 phosphatase dephosphorylates the substrates of cyclin-dependent kinase to facilitate anaphase progression and mitotic exit. In budding yeast, Cdc14 dephosphorylates Fin1, a regulatory subunit of protein phosphatase 1 (PP1), to enable kinetochore localization of Fin1-PP1. We previously showed that kinetochore-localized Fin1-PP1 promotes the removal of the SAC protein Bub1 from the kinetochore during anaphase. We report here that Fin1-PP1 also promotes kinetochore removal of Bub3, the Bub1 partner, but has no effect on another SAC protein Mad1. Moreover, the kinetochore localization of Bub1-Bub3 during anaphase requires Aurora B/Ipl1 kinase activity. We further showed that Fin1-PP1 facilitates the dephosphorylation of kinetochore protein Ndc80, a known Ipl1 substrate. This dephosphorylation reduces kinetochore association of Bub1-Bub3 during anaphase. In addition, we found that untimely Ndc80 dephosphorylation causes viability loss in response to tensionless chromosome attachments. These results suggest that timely localization of Fin1-PP1 to the kinetochore controls the functional window of SAC and is therefore critical for faithful chromosome segregation.

Interplay between mitotic kinesins and the Aurora kinase–PP1 (protein phosphatase 1) axis

2013 ◽  
Vol 41 (6) ◽  
pp. 1761-1765 ◽  
Author(s):  
John C. Meadows
Keyword(s):  
Protein Phosphatase ◽  
Spindle Assembly Checkpoint ◽  
Spindle Checkpoint ◽  
Aurora Kinase ◽  
Protein Phosphatase 1 ◽  
Aurora B ◽  
Spatial Gradient ◽  
Cell Cycle Regulators ◽  
Aurora B Kinase ◽  
Surveillance Mechanism

Correct transmission of genetic information from mother to daughter cells is necessary for development and survival. Accurate segregation is achieved by bipolar attachment of sister kinetochores in each chromatid pair to spindle microtubules emanating from opposite spindle poles, a process known as chromosome bi-orientation. Achieving this requires dynamic interplay between kinetochore proteins, kinesin motor proteins and cell cycle regulators. Chromosome bi-orientation is monitored by a surveillance mechanism known as the SAC (spindle assembly checkpoint). The Aurora B kinase, which is bound to the inner centromere during early mitosis, plays a central role in both chromosome bi-orientation and the spindle checkpoint. The application of tension across centromeres establishes a spatial gradient of high phosphorylation activity at the inner centromere and low phosphorylation activity at the outer kinetochore. This gradient is further refined by the association of PP1 (protein phosphatase 1) to the outer kinetochore, which stabilizes kinetochore–microtubule interactions and silences the spindle checkpoint by dephosphorylating Aurora B kinase targets when chromosome bi-orientation is achieved. In the present review, I discuss emerging evidence that bidirectional cross-talk between mitotic kinesins and the Aurora kinase–PP1 axis is crucial for co-ordinating chromosome bi-orientation and spindle checkpoint signalling in eukaryotes.

scholarly journals Aurora B kinase and protein phosphatase 1 have opposing roles in modulating kinetochore assembly

2008 ◽  
Vol 181 (2) ◽  
pp. 241-254 ◽  
Author(s):  
Michael J. Emanuele ◽  
Weijie Lan ◽  
Miri Jwa ◽  
Stephanie A. Miller ◽  
Clarence S.M. Chan ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Protein Phosphatase ◽  
Protein Phosphatase 1 ◽  
Aurora B ◽  
Aurora B Kinase ◽  
Culture Cells ◽  
Kinetochore Assembly ◽  
M Phase ◽  
Egg Extracts ◽  
Cycle Dependent

The outer kinetochore binds microtubules to control chromosome movement. Outer kinetochore assembly is restricted to mitosis, whereas the inner kinetochore remains tethered to centromeres throughout the cell cycle. The cues that regulate this transient assembly are unknown. We find that inhibition of Aurora B kinase significantly reduces outer kinetochore assembly in Xenopus laevis and human tissue culture cells, frog egg extracts, and budding yeast. In X. leavis M phase extracts, preassembled kinetochores disassemble after inhibiting Aurora B activity with either drugs or antibodies. Kinetochore disassembly, induced by Aurora B inhibition, is rescued by restraining protein phosphatase 1 (PP1) activity. PP1 is necessary for kinetochores to disassemble at the exit from M phase, and purified enzyme is sufficient to cause disassembly on isolated mitotic nuclei. These data demonstrate that Aurora B activity is required for kinetochore maintenance and that PP1 is necessary and sufficient to disassemble kinetochores. We suggest that Aurora B and PP1 coordinate cell cycle–dependent changes in kinetochore assembly though phosphorylation of kinetochore substrates.

scholarly journals The human SKA complex drives the metaphase-anaphase cell cycle transition by recruiting protein phosphatase 1 to kinetochores

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Sushama Sivakumar ◽  
Paweł Ł Janczyk ◽  
Qianhui Qu ◽  
Chad A Brautigam ◽  
P Todd Stukenberg ◽  
...  
Keyword(s):  
Protein Phosphatase ◽  
Force Production ◽  
Dominant Negative ◽  
Protein Phosphatase 1 ◽  
Negative Effects ◽  
Checkpoint Signaling ◽  
Anaphase Onset ◽  
Spindle Microtubules ◽  
Cell Cycle Transition

The spindle- and kinetochore-associated (Ska) complex is essential for normal anaphase onset in mitosis. The C-terminal domain (CTD) of Ska1 binds microtubules and was proposed to facilitate kinetochore movement on depolymerizing spindle microtubules. Here, we show that Ska complex recruits protein phosphatase 1 (PP1) to kinetochores. This recruitment requires the Ska1 CTD, which binds PP1 in vitro and in human HeLa cells. Ska1 lacking its CTD fused to a PP1-binding peptide or fused directly to PP1 rescues mitotic defects caused by Ska1 depletion. Ska1 fusion to catalytically dead PP1 mutant does not rescue and shows dominant negative effects. Thus, the Ska complex, specifically the Ska1 CTD, recruits PP1 to kinetochores to oppose spindle checkpoint signaling kinases and promote anaphase onset. Microtubule binding by Ska, rather than acting in force production for chromosome movement, may instead serve to promote PP1 recruitment to kinetochores fully attached to spindle microtubules at metaphase.

scholarly journals Aurora B Kinase Exists in a Complex with Survivin and INCENP and Its Kinase Activity Is Stimulated by Survivin Binding and Phosphorylation

2002 ◽  
Vol 13 (9) ◽  
pp. 3064-3077 ◽  
Author(s):  
Margaret A. Bolton ◽  
Weijie Lan ◽  
Shannon E. Powers ◽  
Mark L. McCleland ◽  
Jian Kuang ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
Kinase Activity ◽  
Genetic Interactions ◽  
Aurora B ◽  
Hydrodynamic Properties ◽  
Aurora B Kinase ◽  
Survivin Gene ◽  
Spindle Microtubules ◽  
Cycle Dependent

Aurora B regulates chromosome segregation and cytokinesis and is the first protein to be implicated as a regulator of bipolar attachment of spindle microtubules to kinetochores. Evidence from several systems suggests that Aurora B is physically associated with inner centromere protein (INCENP) in mitosis and has genetic interactions with Survivin. It is unclear whether the Aurora B and INCENP interaction is cell cycle regulated and if Survivin physically interacts in this complex. In this study, we cloned theXenopus Survivin gene, examined its association with Aurora B and INCENP, and determined the effect of its binding on Aurora B kinase activity. We demonstrate that in the Xenopusearly embryo, all of the detectable Survivin is in a complex with both Aurora B and INCENP throughout the cell cycle. Survivin and Aurora B bind different domains on INCENP. Aurora B activity is stimulated >10-fold in mitotic extracts; this activation is phosphatase sensitive, and the binding of Survivin is required for full Aurora B activity. We also find the hydrodynamic properties of the Aurora B/Survivin/INCENP complex are cell cycle regulated. Our data indicate that Aurora B kinase activity is regulated by both Survivin binding and cell cycle-dependent phosphorylation.

scholarly journals Kinetochores respond to subtle changes in the stability of microtubule attachments

2021 ◽  
Author(s):  
Jessica D. Warren ◽  
Sarah Y. Valles ◽  
Duane A. Compton
Keyword(s):  
Chromosome Segregation ◽  
Spindle Assembly Checkpoint ◽  
Protein Localization ◽  
Aurora B ◽  
Aurora B Kinase ◽  
Regulatory Enzymes ◽  
Summary Statement ◽  
Spindle Microtubules ◽  
The Stability ◽  
Induced Changes

AbstractProper attachment of spindle microtubules to kinetochores is necessary to satisfy the spindle assembly checkpoint and ensure faithful chromosome segregation. Microtubules detach from kinetochores to correct improperly oriented attachments, and overall kinetochore-microtubule (k-MT) attachment stability is determined in response to regulatory enzymes and the activities of kinetochore-associated microtubule stabilizing and destabilizing proteins. However, it is unknown whether regulatory enzyme activity or kinetochore-associated protein localization respond to subtle changes in k-MT attachment stability. To test for this feedback response, we monitored Aurora B kinase activity and the localization of select kinetochore proteins in metaphase cells following treatments that subtly stabilize or destabilize k-MT attachments using low dose Taxol or UMK57 (an MCAK agonist), respectively. Increasing k-MT stability induced changes in the abundance of some kinetochore proteins. In contrast, reducing k-MT stability induced both increases in Aurora B kinase signaling and changes in the abundance of some kinetochore proteins. Thus, kinetochores dynamically respond to changes in the stability of their attached microtubules. This feedback control contributes to tuning k-MT attachment stability required for efficient error correction to facilitate faithful chromosome segregation.Summary StatementLive cell imaging demonstrates that kinetochore signaling responds to feedback from attached microtubules to tune their stability to ensure faithful chromosome segregation during cell division.

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