scholarly journals BubR1 alterations that reinforce mitotic surveillance act against aneuploidy and cancer

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Robbyn L Weaver ◽  
Jazeel F Limzerwala ◽  
Ryan M Naylor ◽  
Karthik B Jeganathan ◽  
Darren J Baker ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Error Correction ◽  
Chromosome Segregation ◽  
Spindle Assembly Checkpoint ◽  
Spindle Assembly ◽  
Binding Domain ◽  
Amino Terminal ◽  
Binding Domains

BubR1 is a key component of the spindle assembly checkpoint (SAC). Mutations that reduce BubR1 abundance cause aneuploidization and tumorigenesis in humans and mice, whereas BubR1 overexpression protects against these. However, how supranormal BubR1 expression exerts these beneficial physiological impacts is poorly understood. Here, we used Bub1b mutant transgenic mice to explore the role of the amino-terminal (BubR1N) and internal (BubR1I) Cdc20-binding domains of BubR1 in preventing aneuploidy and safeguarding against cancer. BubR1N was necessary, but not sufficient to protect against aneuploidy and cancer. In contrast, BubR1 lacking the internal Cdc20-binding domain provided protection against both, which coincided with improved microtubule-kinetochore attachment error correction and SAC activity. Maximal SAC reinforcement occurred when both the Phe- and D-box of BubR1I were disrupted. Thus, while under- or overexpression of most mitotic regulators impairs chromosome segregation fidelity, certain manipulations of BubR1 can positively impact this process and therefore be therapeutically exploited.

scholarly journals Mad2-independent Spindle Assembly Checkpoint Activation and Controlled Metaphase–Anaphase Transition inDrosophilaS2 Cells

2007 ◽  
Vol 18 (3) ◽  
pp. 850-863 ◽  
Author(s):  
Bernardo Orr ◽  
Hassan Bousbaa ◽  
Claudio E. Sunkel
Keyword(s):  
Chromosome Segregation ◽  
Spindle Assembly Checkpoint ◽  
Spindle Assembly ◽  
Mitotic Progression ◽  
Experimental Conditions ◽  
Checkpoint Activation ◽  
Nuclear Envelope Breakdown ◽  
Chromatin Bridges ◽  
Delay Progression

The spindle assembly checkpoint is essential to maintain genomic stability during cell division. We analyzed the role of the putative Drosophila Mad2 homologue in the spindle assembly checkpoint and mitotic progression. Depletion of Mad2 by RNAi from S2 cells shows that it is essential to prevent mitotic exit after spindle damage, demonstrating its conserved role. Mad2-depleted cells also show accelerated transit through prometaphase and premature sister chromatid separation, fail to form metaphases, and exit mitosis soon after nuclear envelope breakdown with extensive chromatin bridges that result in severe aneuploidy. Interestingly, preventing Mad2-depleted cells from exiting mitosis by a checkpoint-independent arrest allows congression of normally condensed chromosomes. More importantly, a transient mitotic arrest is sufficient for Mad2-depleted cells to exit mitosis with normal patterns of chromosome segregation, suggesting that all the associated phenotypes result from a highly accelerated exit from mitosis. Surprisingly, if Mad2-depleted cells are blocked transiently in mitosis and then released into a media containing a microtubule poison, they arrest with high levels of kinetochore-associated BubR1, properly localized cohesin complex and fail to exit mitosis revealing normal spindle assembly checkpoint activity. This behavior is specific for Mad2 because BubR1-depleted cells fail to arrest in mitosis under these experimental conditions. Taken together our results strongly suggest that Mad2 is exclusively required to delay progression through early stages of prometaphase so that cells have time to fully engage the spindle assembly checkpoint, allowing a controlled metaphase–anaphase transition and normal patterns of chromosome segregation.

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 Dissecting the role of MPS1 in chromosome biorientation and the spindle checkpoint through the small molecule inhibitor reversine

2010 ◽  
Vol 190 (1) ◽  
pp. 73-87 ◽  
Author(s):  
Stefano Santaguida ◽  
Anthony Tighe ◽  
Anna Morena D'Alise ◽  
Stephen S. Taylor ◽  
Andrea Musacchio
Keyword(s):  
Error Correction ◽  
Small Molecule ◽  
Spindle Assembly Checkpoint ◽  
Spindle Checkpoint ◽  
Spindle Assembly ◽  
Dependent Manner ◽  
Crucial Component ◽  
Molecule Inhibitor ◽  
The Relationship

The catalytic activity of the MPS1 kinase is crucial for the spindle assembly checkpoint and for chromosome biorientation on the mitotic spindle. We report that the small molecule reversine is a potent mitotic inhibitor of MPS1. Reversine inhibits the spindle assembly checkpoint in a dose-dependent manner. Its addition to mitotic HeLa cells causes the ejection of Mad1 and the ROD–ZWILCH–ZW10 complex, both of which are important for the spindle checkpoint, from unattached kinetochores. By using reversine, we also demonstrate that MPS1 is required for the correction of improper chromosome–microtubule attachments. We provide evidence that MPS1 acts downstream from the AURORA B kinase, another crucial component of the error correction pathway. Our experiments describe a very useful tool to interfere with MPS1 activity in human cells. They also shed light on the relationship between the error correction pathway and the spindle checkpoint and suggest that these processes are coregulated and are likely to share at least a subset of their catalytic machinery.

scholarly journals Aurora B Tension Sensing Mechanisms in the Kinetochore Ensure Accurate Chromosome Segregation

2021 ◽  
Vol 22 (16) ◽  
pp. 8818
Author(s):  
Shelby L. McVey ◽  
Jenna K. Cosby ◽  
Natalie J. Nannas
Keyword(s):  
Chromosome Segregation ◽  
Birth Defects ◽  
Spindle Assembly Checkpoint ◽  
Spindle Assembly ◽  
Aurora B ◽  
Sister Chromatids ◽  
Congenital Birth Defects ◽  
Biochemical Signals ◽  
Segregation Of Chromosomes

The accurate segregation of chromosomes is essential for the survival of organisms and cells. Mistakes can lead to aneuploidy, tumorigenesis and congenital birth defects. The spindle assembly checkpoint ensures that chromosomes properly align on the spindle, with sister chromatids attached to microtubules from opposite poles. Here, we review how tension is used to identify and selectively destabilize incorrect attachments, and thus serves as a trigger of the spindle assembly checkpoint to ensure fidelity in chromosome segregation. Tension is generated on properly attached chromosomes as sister chromatids are pulled in opposing directions but resisted by centromeric cohesin. We discuss the role of the Aurora B kinase in tension-sensing and explore the current models for translating mechanical force into Aurora B-mediated biochemical signals that regulate correction of chromosome attachments to the spindle.

scholarly journals ULK1 phosphorylates Mad1 to regulate spindle assembly checkpoint

2019 ◽  
Vol 47 (15) ◽  
pp. 8096-8110 ◽  
Author(s):  
Fengjie Yuan ◽  
Ximin Jin ◽  
Dan Li ◽  
Yuanshuai Song ◽  
Nan Zhang ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Cell Cycle Progression ◽  
Spindle Assembly Checkpoint ◽  
Chromosome Instability ◽  
Spindle Assembly ◽  
Cancer Cell Growth ◽  
Serine Threonine Kinase ◽  
Threonine Kinase ◽  
Significant Impairment

Abstract The spindle assembly checkpoint (SAC) ensures the fidelity of chromosome segregation during mitosis. Here, we show that ULK1, a serine/threonine kinase that plays a key role in initiation of autophagy, also has an important function in the activation of SAC. ULK1 phosphorylates the SAC protein Mad1 at Ser546 to recruit Mad1 to kinetochores. Furthermore, Rod/ZW10/Zwilch (RZZ) complex may serve as a receptor for phos-Ser546-Mad1 at kinetochore, since phosphorylation of Mad1 by ULK1 strengthens the interaction between Mad1 and RZZ complex. In addition, deletion of ULK1 increases chromosome instability and cytotoxicity of paclitaxel, resulting in significant impairment of cancer cell growth. These findings highlight the role of ULK1 as a protein kinase controlling the fidelity of chromosome segregation and cell-cycle progression.

scholarly journals Mammalian SWI/SNF chromatin remodeler is essential for reductional meiosis in males

2020 ◽  
Author(s):  
Debashish U. Menon ◽  
Terry Magnuson
Keyword(s):  
Chromosome Segregation ◽  
Spindle Assembly Checkpoint ◽  
Spindle Assembly ◽  
Male Meiosis ◽  
Chromatin Modifications ◽  
Histone H2a ◽  
Centromeric Chromatin ◽  
Chromosome Passenger Complex ◽  
Metaphase I

AbstractBRG1, a catalytic subunit of the mammalian SWI/SNF nucleosome remodeler is essential for male meiosis1. In addition to BRG1, multiple subunits (~10-14) some of which are mutually exclusive, constitute biochemically distinct SWI/SNF subcomplexes, whose functions in gametogenesis remain unknown. Here, we identify a role for the PBAF (Polybromo - Brg1 Associated Factor) complex in the regulation of meiotic cell division. The germ cell-specific depletion of PBAF specific subunit, ARID2 resulted in a metaphase-I arrest. Arid2cKO metaphase-I spermatocytes displayed defects in chromosome organization and spindle assembly. Additionally, mutant centromeres were devoid of Polo-like kinase1 (PLK1), a known regulator of the spindle assembly checkpoint (SAC)2. The loss of PLK1 coincided with an abnormal chromosome-wide expansion of centromeric chromatin modifications such as Histone H3 threonine3 phosphorylation (H3T3P) and Histone H2A threonine120 phosphorylation (H2AT120P) that are critical for chromosome segregation3,4. Consistent with the known role of these histone modifications in chromosome passenger complex (CPC) recruitment, Arid2cKO metaphase-I chromosomes display defects in CPC association. We propose that ARID2 facilitates metaphase-I exit by regulating spindle assembly and centromeric chromatin.

FANCA Controls Mitotic Phosphosignaling Networks To Ensure Genome Stability During Cell Division

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 801-801
Author(s):  
Rikki Enzor ◽  
Zahi Abdul Sater ◽  
Donna Cerabona ◽  
Zejin Sun ◽  
Su-jung Park ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Chromosome Segregation ◽  
Fanconi Anemia ◽  
Spindle Assembly Checkpoint ◽  
Spindle Assembly ◽  
Signaling Network ◽  
Mitotic Apparatus ◽  
Risk Of Cancer

Abstract Fanconi anemia (FA) is a heterogenous genome instability syndrome with a high risk of cancer. The FA proteins are essential for interphase DNA damage repair. However, it is incompletely understood why FA-deficient cells also develop gross aneuploidy and multinucleation, which are symptoms of error-prone chromosome segregation. Emerging evidence indicates that the FA signaling network functions as a guardian of the genome throughout the cell cycle, including chromosome segregation during mitosis. However, the mechanistic aspects of the critical role of the FA signaling in mitosis remain poorly understood. We have recently shown that the FA signaling network localizes to the mitotic apparatus to control the spindle assembly checkpoint and centrosome maintenance (J Clin Invest 2013, in press). The spindle assembly checkpoint (SAC) is a complex tumor suppressor signaling network that prevents premature separation of sister chromatids by delaying the metaphase-to-anaphase transition until all the kinetochores are properly attached to the mitotic spindle. Since weakened SAC promotes stochastic chromosome segregation, mutagenesis and cancer, these findings shed new light on the role of FA signaling in maintenance of genomic stability. We found the subcellular localization of FA proteins to the mitotic apparatus is spatiotemporally regulated as cells divide. Our new data revealed the pathways connecting the FANCA protein with canonical mitotic phosphosignaling networks. We have employed unbiased kinome-wide phospho-mass spectrometry to compare the landscape of abnormalities of mitotic signaling pathways in primary FANCA-/- patient cells and gene-corrected isogenic cells. These experiments led us to identify and quantify a wide range of phosphorylation abnormalities of multiple FANCA-dependent centrosome-, kinetochore- and chromosome-associated regulators of mitosis. Our data illuminated the role for FA signaling in three critical stages of cell division: (1) the spindle assembly checkpoint, (2) anaphase and (3) cytokinesis. Thus, we employed live phase-contrast imaging of primary FANCA-/- patient cells in comparison to gene-corrected cells to separately quantify aberrations in (1) chromosome congression and metaphase-anaphase transition (SAC malfunction), (2) execution of anaphase and (3) completion of cytokinesis. Our findings further our understanding of human cell cycle control and provide new insights into the origins of genomic instability in Fanconi anemia by establishing mechanistic connection between the FANCA protein and key mitotic signaling networks. The identification of cell division pathways regulated by FANCA has implications for future targeted drug development in Fanconi anemia and FA-deficient malignancies in the general population. Disclosures: No relevant conflicts of interest to declare.

scholarly journals The Role of Cdh1p in Maintaining Genomic Stability in Budding Yeast

Genetics ◽  
2003 ◽  
Vol 165 (2) ◽  
pp. 489-503 ◽  
Author(s):  
Karen E Ross ◽  
Orna Cohen-Fix
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
Spindle Assembly Checkpoint ◽  
Chromosome Loss ◽  
Cyclin Dependent Kinase ◽  
Anaphase Promoting Complex ◽  
Growth Defects ◽  
Genes Encoding ◽  
Specificity Factor

Abstract Cdh1p, a substrate specificity factor for the cell cycle-regulated ubiquitin ligase, the anaphase-promoting complex/cyclosome (APC/C), promotes exit from mitosis by directing the degradation of a number of proteins, including the mitotic cyclins. Here we present evidence that Cdh1p activity at the M/G1 transition is important not only for mitotic exit but also for high-fidelity chromosome segregation in the subsequent cell cycle. CDH1 showed genetic interactions with MAD2 and PDS1, genes encoding components of the mitotic spindle assembly checkpoint that acts at metaphase to prevent premature chromosome segregation. Unlike cdh1Δ and mad2Δ single mutants, the mad2Δ cdh1Δ double mutant grew slowly and exhibited high rates of chromosome and plasmid loss. Simultaneous deletion of PDS1 and CDH1 caused extensive chromosome missegregation and cell death. Our data suggest that at least part of the chromosome loss can be attributed to kinetochore/spindle problems. Our data further suggest that Cdh1p and Sic1p, a Cdc28p/Clb inhibitor, have overlapping as well as nonoverlapping roles in ensuring proper chromosome segregation. The severe growth defects of both mad2Δ cdh1Δ and pds1Δ cdh1Δ strains were rescued by overexpressing Swe1p, a G2/M inhibitor of the cyclin-dependent kinase, Cdc28p/Clb. We propose that the failure to degrade cyclins at the end of mitosis leaves cdh1Δ mutant strains with abnormal Cdc28p/Clb activity that interferes with proper chromosome segregation.

scholarly journals Monitoring the fidelity of mitotic chromosome segregation by the spindle assembly checkpoint

2011 ◽  
Vol 44 (5) ◽  
pp. 391-400 ◽  
Author(s):  
P. Silva ◽  
J. Barbosa ◽  
A. V. Nascimento ◽  
J. Faria ◽  
R. Reis ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Spindle Assembly Checkpoint ◽  
Mitotic Chromosome ◽  
Spindle Assembly

scholarly journals Centromere-localized Aurora B kinase is required for the fidelity of chromosome segregation

2019 ◽  
Vol 219 (2) ◽  
Author(s):  
Cai Liang ◽  
Zhenlei Zhang ◽  
Qinfu Chen ◽  
Haiyan Yan ◽  
Miao Zhang ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Essential Role ◽  
Spindle Assembly Checkpoint ◽  
Histone H3 ◽  
Spindle Assembly ◽  
Aurora B ◽  
Aurora B Kinase ◽  
Chromosome Missegregation ◽  
Proper Timing ◽  
Segregation Of Chromosomes

Aurora B kinase plays an essential role in chromosome bi-orientation, which is a prerequisite for equal segregation of chromosomes during mitosis. However, it remains largely unclear whether centromere-localized Aurora B is required for faithful chromosome segregation. Here we show that histone H3 Thr-3 phosphorylation (H3pT3) and H2A Thr-120 phosphorylation (H2ApT120) can independently recruit Aurora B. Disrupting H3pT3-mediated localization of Aurora B at the inner centromere impedes the decline in H2ApT120 during metaphase and causes H2ApT120-dependent accumulation of Aurora B at the kinetochore-proximal centromere. Consequently, silencing of the spindle assembly checkpoint (SAC) is delayed, whereas the fidelity of chromosome segregation is negligibly affected. Further eliminating an H2ApT120-dependent pool of Aurora B restores proper timing for SAC silencing but increases chromosome missegregation. Our data indicate that H2ApT120-mediated localization of Aurora B compensates for the loss of an H3pT3-dependent pool of Aurora B to correct improper kinetochore–microtubule attachments. This study provides important insights into how centromeric Aurora B regulates SAC and kinetochore attachment to microtubules to ensure error-free chromosome segregation.

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