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.

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 BUB-1 promotes amphitelic chromosome biorientation via multiple activities at the kinetochore

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Frances Edwards ◽  
Gilliane Maton ◽  
Nelly Gareil ◽  
Julie C Canman ◽  
Julien Dumont
Keyword(s):  
Chromosome Segregation ◽  
Spindle Assembly Checkpoint ◽  
Underlying Mechanism ◽  
Microtubule Assembly ◽  
Spindle Poles ◽  
Microtubule Attachment ◽  
Anaphase Onset ◽  
Chromatid Segregation ◽  
Associated Proteins ◽  
Chromosome Attachment

Accurate chromosome segregation relies on bioriented amphitelic attachments of chromosomes to microtubules of the mitotic spindle, in which sister chromatids are connected to opposite spindle poles. BUB-1 is a protein of the Spindle Assembly Checkpoint (SAC) that coordinates chromosome attachment with anaphase onset. BUB-1 is also required for accurate sister chromatid segregation independently of its SAC function, but the underlying mechanism remains unclear. Here we show that, in Caenorhabditis elegans embryos, BUB-1 accelerates the establishment of non-merotelic end-on kinetochore-microtubule attachments by recruiting the RZZ complex and its downstream partner dynein-dynactin at the kinetochore. In parallel, BUB-1 limits attachment maturation by the SKA complex. This activity opposes kinetochore-microtubule attachment stabilisation promoted by CLS-2CLASP-dependent kinetochore-microtubule assembly. BUB-1 is therefore a SAC component that coordinates the function of multiple downstream kinetochore-associated proteins to ensure accurate chromosome segregation.

scholarly journals Release of Mps1 from kinetochores is crucial for timely anaphase onset

2010 ◽  
Vol 191 (2) ◽  
pp. 281-290 ◽  
Author(s):  
Nannette Jelluma ◽  
Tobias B. Dansen ◽  
Tale Sliedrecht ◽  
Nicholas P. Kwiatkowski ◽  
Geert J.P.L. Kops
Keyword(s):  
Error Correction ◽  
Chromosome Segregation ◽  
Kinase Activity ◽  
Mitotic Checkpoint ◽  
Normal Chromosome ◽  
Half Time ◽  
Anaphase Onset ◽  
Chromosome Attachment

Mps1 kinase activity is required for proper chromosome segregation during mitosis through its involvements in microtubule–chromosome attachment error correction and the mitotic checkpoint. Mps1 dynamically exchanges on unattached kinetochores but is largely removed from kinetochores in metaphase. Here we show that Mps1 promotes its own turnover at kinetochores and that removal of Mps1 upon chromosome biorientation is a prerequisite for mitotic checkpoint silencing. Inhibition of Mps1 activity increases its half-time of recovery at unattached kinetochores and causes accumulation of Mps1 protein at these sites. Strikingly, preventing dissociation of active Mps1 from kinetochores delays anaphase onset despite normal chromosome attachment and alignment, and high interkinetochore tension. This delay is marked by continued recruitment of Mad1 and Mad2 to bioriented chromosomes and is attenuated by Mad2 depletion, indicating chronic engagement of the mitotic checkpoint in metaphase. We propose that release of Mps1 from kinetochores is essential for mitotic checkpoint silencing and a fast metaphase-to-anaphase transition.

scholarly journals Delineating the contribution of Spc105-bound PP1 to spindle checkpoint silencing and kinetochore microtubule attachment regulation

2019 ◽  
Vol 218 (12) ◽  
pp. 3926-3942 ◽  
Author(s):  
Babhrubahan Roy ◽  
Vikash Verma ◽  
Janice Sim ◽  
Adrienne Fontan ◽  
Ajit P. Joglekar
Keyword(s):  
Cell Division ◽  
Error Correction ◽  
Chromosome Segregation ◽  
Protein Phosphatase ◽  
Spindle Assembly Checkpoint ◽  
Spindle Checkpoint ◽  
Spindle Assembly ◽  
Protein Phosphatase 1 ◽  
Microtubule Attachment ◽  
Error Correction Mechanism

Accurate chromosome segregation during cell division requires the spindle assembly checkpoint (SAC), which detects unattached kinetochores, and an error correction mechanism that destabilizes incorrect kinetochore–microtubule attachments. While the SAC and error correction are both regulated by protein phosphatase 1 (PP1), which silences the SAC and stabilizes kinetochore–microtubule attachments, how these distinct PP1 functions are coordinated remains unclear. Here, we investigate the contribution of PP1, docked on its conserved kinetochore receptor Spc105/Knl1, to SAC silencing and attachment regulation. We find that Spc105-bound PP1 is critical for SAC silencing but dispensable for error correction; in fact, reduced PP1 docking on Spc105 improved chromosome segregation and viability of mutant/stressed states. We additionally show that artificially recruiting PP1 to Spc105/Knl1 before, but not after, chromosome biorientation interfered with error correction. These observations lead us to propose that recruitment of PP1 to Spc105/Knl1 is carefully regulated to ensure that chromosome biorientation precedes SAC silencing, thereby ensuring accurate chromosome segregation.

scholarly journals Glc7/Protein Phosphatase 1 Regulatory Subunits Can Oppose the Ipl1/Aurora Protein Kinase by Redistributing Glc7

2006 ◽  
Vol 26 (7) ◽  
pp. 2648-2660 ◽  
Author(s):  
Benjamin A. Pinsky ◽  
Chitra V. Kotwaliwale ◽  
Sean Y. Tatsutani ◽  
Christopher A. Breed ◽  
Sue Biggins
Keyword(s):  
Protein Kinase ◽  
Chromosome Segregation ◽  
Protein Phosphatase ◽  
Kinase Activity ◽  
Budding Yeast ◽  
Protein Phosphatase 1 ◽  
Wild Type ◽  
Regulatory Subunits ◽  
The Relationship ◽  
Mutant Cells

ABSTRACT Faithful chromosome segregation depends on the opposing activities of the budding yeast Glc7/PP1 protein phosphatase and Ipl1/Aurora protein kinase. We explored the relationship between Glc7 and Ipl1 and found that the phosphorylation of the Ipl1 substrate, Dam1, was altered by decreased Glc7 activity, whereas Ipl1 levels, localization, and kinase activity were not. These data strongly suggest that Glc7 ensures accurate chromosome segregation by dephosphorylating Ipl1 targets rather than regulating the Ipl1 kinase. To identify potential Glc7 and Ipl1 substrates, we isolated ipl1-321 dosage suppressors. Seven genes (SDS22, BUD14, GIP3, GIP4, SOL1, SOL2, and PEX31) encode newly identified ipl1 dosage suppressors, and all 10 suppressors encode proteins that physically interact with Glc7. The overexpression of the Gip3 and Gip4 suppressors altered Glc7 localization, indicating they are previously unidentified Glc7 regulatory subunits. In addition, the overexpression of Gip3 and Gip4 from the galactose promoter restored Dam1 phosphorylation in ipl1-321 mutant cells and caused wild-type cells to arrest in metaphase with unsegregated chromosomes, suggesting that Gip3 and Gip4 overexpression impairs Glc7's mitotic functions. We therefore propose that the overexpression of Glc7 regulatory subunits can titrate Glc7 away from relevant Ipl1 targets and thereby suppress ipl1-321 cells by restoring the balance of phosphatase/kinase activity.

scholarly journals Protein Phosphatase 1 inactivates Mps1 to ensure efficient Spindle Assembly Checkpoint silencing

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Margarida Moura ◽  
Mariana Osswald ◽  
Nelson Leça ◽  
João Barbosa ◽  
António J Pereira ◽  
...  
Keyword(s):  
Protein Phosphatase ◽  
Spindle Assembly Checkpoint ◽  
Spindle Assembly ◽  
Mitotic Exit ◽  
Protein Phosphatase 1 ◽  
Anaphase Onset ◽  
Phosphorylation Cascade ◽  
Spindle Microtubules ◽  
Early Mitosis

Faithfull genome partitioning during cell division relies on the Spindle Assembly Checkpoint (SAC), a conserved signaling pathway that delays anaphase onset until all chromosomes are attached to spindle microtubules. Mps1 kinase is an upstream SAC regulator that promotes the assembly of an anaphase inhibitor through a sequential multi-target phosphorylation cascade. Thus, the SAC is highly responsive to Mps1, whose activity peaks in early mitosis as a result of its T-loop autophosphorylation. However, the mechanism controlling Mps1 inactivation once kinetochores attach to microtubules and the SAC is satisfied remains unknown. Here we show in vitro and in Drosophila that Protein Phosphatase 1 (PP1) inactivates Mps1 by dephosphorylating its T-loop. PP1-mediated dephosphorylation of Mps1 occurs at kinetochores and in the cytosol, and inactivation of both pools of Mps1 during metaphase is essential to ensure prompt and efficient SAC silencing. Overall, our findings uncover a mechanism of SAC inactivation required for timely mitotic exit.

scholarly journals Chromosome biorientation and APC activity remain uncoupled in oocytes with reduced volume

2017 ◽  
Vol 216 (12) ◽  
pp. 3949-3957 ◽  
Author(s):  
Simon I.R. Lane ◽  
Keith T. Jones
Keyword(s):  
Cell Volume ◽  
Chromosome Segregation ◽  
Spindle Assembly Checkpoint ◽  
Spindle Assembly ◽  
Anaphase Promoting Complex ◽  
Chromosome Missegregation ◽  
Anaphase Onset ◽  
Reduced Volume ◽  
Chromosome Attachment ◽  
Meiosis I

The spindle assembly checkpoint (SAC) prevents chromosome missegregation by coupling anaphase onset with correct chromosome attachment and tension to microtubules. It does this by generating a diffusible signal from free kinetochores into the cytoplasm, inhibiting the anaphase-promoting complex (APC). The volume in which this signal remains effective is unknown. This raises the possibility that cell volume may be the reason the SAC is weak, and chromosome segregation error-prone, in mammalian oocytes. Here, by a process of serial bisection, we analyzed the influence of oocyte volume on the ability of the SAC to inhibit bivalent segregation in meiosis I. We were able to generate oocytes with cytoplasmic volumes reduced by 86% and observed changes in APC activity consistent with increased SAC control. However, bivalent biorientation remained uncoupled from APC activity, leading to error-prone chromosome segregation. We conclude that volume is one factor contributing to SAC weakness in oocytes. However, additional factors likely uncouple chromosome biorientation with APC activity.

scholarly journals Minimization of a harmful cross-talk between mitotic checkpoint silencing and error correction

2018 ◽  
Author(s):  
Babhrubahan Roy ◽  
Vikash Verma ◽  
Janice Sim ◽  
Adrienne Fontan ◽  
Ajit P. Joglekar
Keyword(s):  
Error Correction ◽  
Chromosome Segregation ◽  
Cross Talk ◽  
Protein Phosphatase ◽  
Spindle Assembly Checkpoint ◽  
Mitotic Checkpoint ◽  
Spindle Pole ◽  
Protein Phosphatase 1 ◽  
Spindle Poles ◽  
Combined Action

AbstractAccurate chromosome segregation during cell division requires that the pair of sister kinetochores on each chromosome attach to microtubules originating from opposite spindle poles. This is ensured by the combined action of the Spindle Assembly Checkpoint (SAC), which detects unattached kinetochores, and an error correction mechanism that destabilizes incorrect attachment of both sister kinetochores to the same spindle pole. These processes are downregulated by Protein Phosphatase 1 (PP1), which both silences the SAC and stabilizes kinetochore-microtubule attachments. We find that this dual PP1 role can be problematic: if PP1 is recruited to the kinetochore for SAC silencing prior to chromosome biorientation, it interferes with error correction. We show that to mitigate this cross-talk, the yeast kinetochore uses independent PP1 sources to stabilize correct attachments and to silence the SAC, and also delays the recruitment of PP1 for SAC silencing. Consequently, chromosome biorientation precedes SAC silencing ensuring accurate chromosome segregation.

scholarly journals The Human Spindle Assembly Checkpoint Protein Bub3 Is Required for the Establishment of Efficient Kinetochore–Microtubule Attachments

2008 ◽  
Vol 19 (4) ◽  
pp. 1798-1813 ◽  
Author(s):  
Elsa Logarinho ◽  
Tatiana Resende ◽  
Cláudia Torres ◽  
Hassan Bousbaa
Keyword(s):  
Spindle Assembly Checkpoint ◽  
Spindle Assembly ◽  
Checkpoint Proteins ◽  
Anaphase Onset ◽  
Chromosome Congression ◽  
The Status ◽  
Chromosome Attachment ◽  
High Resolution Microscopy ◽  
Spindle Assembly Checkpoint Protein

The spindle assembly checkpoint monitors the status of kinetochore–microtubule (K-MT) attachments and delays anaphase onset until full metaphase alignment is achieved. Recently, the role of spindle assembly checkpoint proteins was expanded with the discovery that BubR1 and Bub1 are implicated in the regulation of K-MT attachments. One unsolved question is whether Bub3, known to form cell cycle constitutive complexes with both BubR1 and Bub1, is also required for proper chromosome-to-spindle attachments. Using RNA interference and high-resolution microscopy, we analyzed K-MT interactions in Bub3-depleted cells and compared them to those in Bub1- or BubR1-depleted cells. We found that Bub3 is essential for the establishment of correct K-MT attachments. In contrast to BubR1 depletion, which severely compromises chromosome attachment and alignment, we found Bub3 and Bub1 depletions to produce defective K-MT attachments that, however, still account for significant chromosome congression. After Aurora B inhibition, alignment defects become severer in Bub3- and Bub1-depleted cells, while partially rescued in BubR1-depleted cells, suggesting that Bub3 and Bub1 depletions perturb K-MT attachments distinctly from BubR1. Interestingly, misaligned chromosomes in Bub3- and Bub1-depleted cells were found to be predominantly bound in a side-on configuration. We propose that Bub3 promotes the formation of stable end-on bipolar attachments.

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