scholarly journals Deregulation of Chromosome Segregation and Cancer

2020 ◽  
Vol 4 (1) ◽  
pp. 257-278 ◽  
Author(s):  
Natalie L. Curtis ◽  
Gian Filippo Ruda ◽  
Paul Brennan ◽  
Victor M. Bolanos-Garcia
Keyword(s):  
Cell Division ◽  
Chromosome Segregation ◽  
Drug Targets ◽  
Spindle Assembly Checkpoint ◽  
Genetic Material ◽  
Cancer Therapies ◽  
Mitotic Spindle Assembly ◽  
Protein Components ◽  
Stable Genome ◽  
Segregation Of Chromosomes

The mitotic spindle assembly checkpoint (SAC) is an intricate cell signaling system that ensures the high fidelity and timely segregation of chromosomes during cell division. Mistakes in this process can lead to the loss, gain, or rearrangement of the genetic material. Gross chromosomal aberrations are usually lethal but can cause birth and development defects as well as cancer. Despite advances in the identification of SAC protein components, important details of the interactions underpinning chromosome segregation regulation remain to be established. This review discusses the current understanding of the function, structure, mode of regulation, and dynamics of the assembly and disassembly of SAC subcomplexes, which ultimately safeguard the accurate transmission of a stable genome to descendants. We also discuss how diverse oncoviruses take control of human cell division by exploiting the SAC and the potential of this signaling circuitry as a pool of drug targets to develop effective cancer therapies.

scholarly journals Synchronizing chromosome segregation by flux-dependent force equalization at kinetochores

2009 ◽  
Vol 186 (1) ◽  
pp. 11-26 ◽  
Author(s):  
Irina Matos ◽  
António J. Pereira ◽  
Mariana Lince-Faria ◽  
Lisa A. Cameron ◽  
Edward D. Salmon ◽  
...  
Keyword(s):  
Cell Division ◽  
Chromosome Segregation ◽  
Mechanical Model ◽  
Spindle Assembly Checkpoint ◽  
Spindle Assembly ◽  
S2 Cells ◽  
Spindle Microtubule ◽  
Anaphase Onset ◽  
Drosophila S2 Cells ◽  
Segregation Of Chromosomes

The synchronous movement of chromosomes during anaphase ensures their correct inheritance in every cell division. This reflects the uniformity of spindle forces acting on chromosomes and their simultaneous entry into anaphase. Although anaphase onset is controlled by the spindle assembly checkpoint, it remains unknown how spindle forces are uniformly distributed among different chromosomes. In this paper, we show that tension uniformity at metaphase kinetochores and subsequent anaphase synchrony in Drosophila S2 cells are promoted by spindle microtubule flux. These results can be explained by a mechanical model of the spindle where microtubule poleward translocation events associated with flux reflect relaxation of the kinetochore–microtubule interface, which accounts for the redistribution and convergence of kinetochore tensions in a timescale comparable to typical metaphase duration. As predicted by the model, experimental acceleration of mitosis precludes tension equalization and anaphase synchrony. We propose that flux-dependent equalization of kinetochore tensions ensures a timely and uniform maturation of kinetochore–microtubule interfaces necessary for error-free and coordinated segregation of chromosomes in anaphase.

scholarly journals Shugoshin: From a Perspective of Clinical Disorders

2021 ◽  
Author(s):  
Ravinder Kumar ◽  
Meenakshi Agarwal
Keyword(s):  
Cell Division ◽  
Cancer Therapy ◽  
Genetic Material ◽  
Altered Level ◽  
Protein Factor ◽  
Clinical Disorders ◽  
Dividing Cells ◽  
Clinical Consequences ◽  
Cellular Genome ◽  
Segregation Of Chromosomes

Proper and timely segregation of cellular genome is an important and a prime requirement of all cell division programmes. Mis-segregation of chromosomes and resulting aneuploidy leads to several clinical consequences. Over the years, shugoshin emerges as a key protein factor involved in the segregation of genetic material in dividing cells. Deletion or altered level of shugoshin is reported in several human malignancies, as a result, shugoshin now emerges as an important tumour associated gene and a possible target for cancer therapy. Apart from the role in cancer, recent studies also showed the involvement of shugoshin in several other clinical disorders. Through this review, we tried to highlight the clinical relevance of shugoshin.

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.

scholarly journals The Opposing Functions of Protein Kinases and Phosphatases in Chromosome Bipolar Attachment

2019 ◽  
Vol 20 (24) ◽  
pp. 6182 ◽  
Author(s):  
Delaney Sherwin ◽  
Yanchang Wang
Keyword(s):  
Cell Division ◽  
Chromosome Segregation ◽  
Protein Phosphatase ◽  
Spindle Assembly Checkpoint ◽  
Model Organism ◽  
Eukaryotic Cells ◽  
Genome Integrity ◽  
Chromosome Missegregation ◽  
Spindle Poles ◽  
Mitosis And Meiosis

Accurate chromosome segregation during cell division is essential to maintain genome integrity in all eukaryotic cells, and chromosome missegregation leads to aneuploidy and therefore represents a hallmark of many cancers. Accurate segregation requires sister kinetochores to attach to microtubules emanating from opposite spindle poles, known as bipolar attachment or biorientation. Recent studies have uncovered several mechanisms critical to chromosome bipolar attachment. First, a mechanism exists to ensure that the conformation of sister centromeres is biased toward bipolar attachment. Second, the phosphorylation of some kinetochore proteins destabilizes kinetochore attachment to facilitate error correction, but a protein phosphatase reverses this phosphorylation. Moreover, the activity of the spindle assembly checkpoint is regulated by kinases and phosphatases at the kinetochore, and this checkpoint prevents anaphase entry in response to faulty kinetochore attachment. The fine-tuned kinase/phosphatase balance at kinetochores is crucial for faithful chromosome segregation during both mitosis and meiosis. Here, we discuss the function and regulation of protein phosphatases in the establishment of chromosome bipolar attachment with a focus on the model organism budding yeast.

scholarly journals ConnectingGCN5’s centromeric SAGA to the mitotic tension-sensing checkpoint

2018 ◽  
Vol 29 (18) ◽  
pp. 2201-2212 ◽  
Author(s):  
Emily L. Petty ◽  
Masha Evpak ◽  
Lorraine Pillus
Keyword(s):  
Chromosome Segregation ◽  
Sister Chromatid ◽  
Spindle Assembly Checkpoint ◽  
Binding Function ◽  
Chromatid Cohesion ◽  
Histone H3 Variant ◽  
Spindle Microtubules ◽  
Low Tension ◽  
Centromere Histone H3 ◽  
Segregation Of Chromosomes

Multiple interdependent mechanisms ensure faithful segregation of chromosomes during cell division. Among these, the spindle assembly checkpoint monitors attachment of spindle microtubules to the centromere of each chromosome, whereas the tension-sensing checkpoint monitors the opposing forces between sister chromatid centromeres for proper biorientation. We report here a new function for the deeply conserved Gcn5 acetyltransferase in the centromeric localization of Rts1, a key player in the tension-sensing checkpoint. Rts1 is a regulatory component of protein phopshatase 2A, a near universal phosphatase complex, which is recruited to centromeres by the Shugoshin (Sgo) checkpoint component under low-tension conditions to maintain sister chromatid cohesion. We report that loss of Gcn5 disrupts centromeric localization of Rts1. Increased RTS1 dosage robustly suppresses gcn5∆ cell cycle and chromosome segregation defects, including restoration of Rts1 to centromeres. Sgo1’s Rts1-binding function also plays a key role in RTS1 dosage suppression of gcn5∆ phenotypes. Notably, we have identified residues of the centromere histone H3 variant Cse4 that function in these chromosome segregation-related roles of RTS1. Together, these findings expand the understanding of the mechanistic roles of Gcn5 and Cse4 in chromosome segregation.

scholarly journals An actin-dependent spindle position checkpoint ensures the asymmetric division in mouse oocytes

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Aïcha Metchat ◽  
Manuel Eguren ◽  
Julius M. Hossain ◽  
Antonio Z. Politi ◽  
Sébastien Huet ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Spindle Assembly Checkpoint ◽  
Cell Cortex ◽  
Cell Periphery ◽  
Actin Network ◽  
Metaphase Arrest ◽  
Homologous Chromosomes ◽  
Close Proximity ◽  
Spindle Position ◽  
Segregation Of Chromosomes

Abstract Faithful chromosome segregation, during meiosis, is of critical importance to prevent aneuploidy in the resulting embryo. In mammalian oocytes, the segregation of homologous chromosomes takes place with the spindle located at the cell’s periphery. The spindle is often assembled close to the centre of the cell, which necessitates the actin network for spindle transport to the cell cortex. In this study, we investigate how the segregation of chromosomes is coordinated with the positioning of the metaphase I spindle. We develop different assays to perturb the spindle’s position and to delay its relocation to the cell periphery. We find that anaphase is delayed until the spindle is positioned in close proximity with the oocyte cortex. We further show that the metaphase arrest is dependent on a functional actin network, in addition to the spindle assembly checkpoint. Our work provides the first evidence for the existence of a functional spindle position checkpoint.

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 Mechanical Mechanisms of Chromosome Segregation

Cells ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 465
Author(s):  
Maya I. Anjur-Dietrich ◽  
Colm P. Kelleher ◽  
Daniel J. Needleman
Keyword(s):  
Cell Division ◽  
Chromosome Segregation ◽  
Genetic Material ◽  
Evolutionary Genetics ◽  
Force Generation ◽  
Coarse Grained ◽  
Subcellular Structure ◽  
Daughter Cells ◽  
The Past ◽  
The Future

Chromosome segregation—the partitioning of genetic material into two daughter cells—is one of the most crucial processes in cell division. In all Eukaryotes, chromosome segregation is driven by the spindle, a microtubule-based, self-organizing subcellular structure. Extensive research performed over the past 150 years has identified numerous commonalities and contrasts between spindles in different systems. In this review, we use simple coarse-grained models to organize and integrate previous studies of chromosome segregation. We discuss sites of force generation in spindles and fundamental mechanical principles that any understanding of chromosome segregation must be based upon. We argue that conserved sites of force generation may interact differently in different spindles, leading to distinct mechanical mechanisms of chromosome segregation. We suggest experiments to determine which mechanical mechanism is operative in a particular spindle under study. Finally, we propose that combining biophysical experiments, coarse-grained theories, and evolutionary genetics will be a productive approach to enhance our understanding of chromosome segregation in the future.

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 Synchronous chromosome segregation in mouse oocytes is ensured by biphasic securin destruction and cyclin B1-Cdk1

2019 ◽  
Author(s):  
Christopher Thomas ◽  
Mark D. Levasseur ◽  
Rebecca J. Harris ◽  
Owen R. Davies ◽  
Suzanne Madgwick
Keyword(s):  
At Risk ◽  
Cell Division ◽  
Chromosome Segregation ◽  
Cyclin B1 ◽  
Cleavage Furrow ◽  
Large Excess ◽  
Cleavage Activity ◽  
Mouse Oocytes ◽  
Key Residues ◽  
Segregation Of Chromosomes

AbstractSuccessful cell division relies on the faithful segregation of chromosomes. If chromosomes segregate prematurely the cell is at risk of aneuploidy. Alternatively, if cell division is attempted in the absence of complete chromosome segregation, non-segregated chromosomes can become trapped within the cleavage furrow and the cell can lose viability. Securin plays a key role in this process, acting as a pseudosubstrate to inhibit the protease separase that functions to cleave the cohesin rings that hold chromosomes together. Consequently, securin must be depleted ahead of anaphase, ensuring chromosome segregation occurs in time with the anaphase trigger. Here we find that MI mouse oocytes contain a large excess of securin over separase and reveal the existence of a novel mechanism that functions to promote the destruction of excess securin in prometaphase. Critically, this mechanism relies on key residues that are only exposed when securin is not bound to separase. We suggest that the majority of non-separase bound securin is removed by this mechanism, allowing for separase activity to be protected until just before anaphase. In addition, we further demonstrate the importance of complementary mechanisms of separase inhibition by directly measuring cleavage activity in live oocytes, confirming that both securin and inhibition by cyclin B1-Cdk1 are independently sufficient to prevent premature separase activation.

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