scholarly journals Real-time dynamics of Plasmodium NDC80 reveals unusual modes of chromosome segregation during parasite proliferation

2019 ◽  
Author(s):  
Mohammad Zeeshan ◽  
Rajan Pandey ◽  
David J.P. Ferguson ◽  
Eelco C. Tromer ◽  
Robert Markus ◽  
...  
Keyword(s):  
Cell Division ◽  
Chromosome Segregation ◽  
Mitotic Spindle ◽  
Complex Structure ◽  
Eukaryotic Cell ◽  
Parasite Life Cycle ◽  
Mitotic Apparatus ◽  
Time Dynamics ◽  
Ndc80 Complex ◽  
Ideal Tool

AbstractEukaryotic cell proliferation requires chromosome replication and precise segregation to ensure daughter cells have identical genomic copies. The genus Plasmodium, the causative agent of malaria, displays remarkable aspects of nuclear division throughout its lifecycle to meet some peculiar and unique challenges of DNA replication and chromosome segregation. The parasite undergoes atypical endomitosis and endoreduplication with an intact nuclear membrane and intranuclear mitotic spindle. To understand these diverse modes of Plasmodium cell division, we have studied the behaviour and composition of the outer kinetochore NDC80 complex, a key part of the mitotic apparatus that attaches the centromere of chromosomes to microtubules of the mitotic spindle. Using NDC80-GFP live-cell imaging in Plasmodium berghei we observe dynamic spatiotemporal changes during proliferation, including highly unusual kinetochore arrangements during sexual stages. We identify a very divergent candidate for the SPC24 subunit of the NDC80 complex, previously thought to be missing in Plasmodium, which completes a canonical, albeit unusual, NDC80 complex structure. Altogether, our studies reveal the kinetochore as an ideal tool to investigate the non-canonical modes of chromosome segregation and cell division in Plasmodium.Summary StatementThe dynamic localization of kinetochore marker NDC80 protein complex during proliferative stages of the malaria parasite life cycle reveals unique modes of chromosome segregation.

scholarly journals Ric-8A and Giα Recruit LGN, NuMA, and Dynein to the Cell Cortex To Help Orient the Mitotic Spindle

2010 ◽  
Vol 30 (14) ◽  
pp. 3519-3530 ◽  
Author(s):  
Geoffrey E. Woodard ◽  
Ning-Na Huang ◽  
Hyeseon Cho ◽  
Toru Miki ◽  
Gregory G. Tall ◽  
...  
Keyword(s):  
Cell Division ◽  
Mammalian Cell ◽  
Pertussis Toxin ◽  
Mitotic Spindle ◽  
Fluorescent Protein ◽  
Model Organisms ◽  
Cell Cortex ◽  
Nucleotide Exchange ◽  
Mitotic Apparatus ◽  
Signaling Complex

ABSTRACT In model organisms, resistance to inhibitors of cholinesterase 8 (Ric-8), a G protein α (Gα) subunit guanine nucleotide exchange factor (GEF), functions to orient mitotic spindles during asymmetric cell divisions; however, whether Ric-8A has any role in mammalian cell division is unknown. We show here that Ric-8A and Gαi function to orient the metaphase mitotic spindle of mammalian adherent cells. During mitosis, Ric-8A localized at the cell cortex, spindle poles, centromeres, central spindle, and midbody. Pertussis toxin proved to be a useful tool in these studies since it blocked the binding of Ric-8A to Gαi, thus preventing its GEF activity for Gαi. Linking Ric-8A signaling to mammalian cell division, treatment of cells with pertussis toxin, reduction of Ric-8A expression, or decreased Gαi expression similarly affected metaphase cells. Each treatment impaired the localization of LGN (GSPM2), NuMA (microtubule binding nuclear mitotic apparatus protein), and dynein at the metaphase cell cortex and disturbed integrin-dependent mitotic spindle orientation. Live cell imaging of HeLa cells expressing green fluorescent protein-tubulin also revealed that reduced Ric-8A expression prolonged mitosis, caused occasional mitotic arrest, and decreased mitotic spindle movements. These data indicate that Ric-8A signaling leads to assembly of a cortical signaling complex that functions to orient the mitotic spindle.

scholarly journals Chromosome detachment from the nuclear envelope is required for genomic stability in closed mitosis

2019 ◽  
Vol 30 (13) ◽  
pp. 1578-1586 ◽  
Author(s):  
Rey-Huei Chen
Keyword(s):  
Nuclear Envelope ◽  
Chromosome Segregation ◽  
Mitotic Spindle ◽  
Chromosome Region ◽  
Aurora B ◽  
Chromosome Movement ◽  
Full Extension ◽  
Mitotic Apparatus ◽  
Chromosome Attachment ◽  
Specific Locus

Mitosis in metazoans involves detachment of chromosomes from the nuclear envelope (NE) and NE breakdown, whereas yeasts maintain the nuclear structure throughout mitosis. It remains unknown how chromosome attachment to the NE might affect chromosome movement in yeast. By using a rapamycin-induced dimerization system to tether a specific locus of the chromosome to the NE, I found that the tethering delays the separation and causes missegregation of the region distal to the tethered site. The phenotypes are exacerbated by mutations in kinetochore components and Aurora B kinase Ipl1. The chromosome region proximal to the centromere is less affected by the tether, but it exhibits excessive oscillation before segregation. Furthermore, the tether impacts full extension of the mitotic spindle, causing abrupt shrinkage or bending of the spindle in shortened anaphase. The study supports detachment of chromosomes from the NE being required for faithful chromosome segregation in yeast and segregation of tethered chromosomes being dependent on a fully functional mitotic apparatus.

scholarly journals Moesin and its activating kinase Slik are required for cortical stability and microtubule organization in mitotic cells

2008 ◽  
Vol 180 (4) ◽  
pp. 739-746 ◽  
Author(s):  
Sébastien Carreno ◽  
Ilektra Kouranti ◽  
Edith Szafer Glusman ◽  
Margaret T. Fuller ◽  
Arnaud Echard ◽  
...  
Keyword(s):  
Cell Division ◽  
Chromosome Segregation ◽  
Mitotic Spindle ◽  
Cortical Actin ◽  
Microtubule Organization ◽  
Abnormal Distribution ◽  
Multistep Process ◽  
Cortical Contractility ◽  
Spatiotemporal Control ◽  
Shape Changes

Cell division requires cell shape changes involving the localized reorganization of cortical actin, which must be tightly linked with chromosome segregation operated by the mitotic spindle. How this multistep process is coordinated remains poorly understood. In this study, we show that the actin/membrane linker moesin, the single ERM (ezrin, radixin, and moesin) protein in Drosophila melanogaster, is required to maintain cortical stability during mitosis. Mitosis onset is characterized by a burst of moesin activation mediated by a Slik kinase–dependent phosphorylation. Activated moesin homogenously localizes at the cortex in prometaphase and is progressively restricted at the equator in later stages. Lack of moesin or inhibition of its activation destabilized the cortex throughout mitosis, resulting in severe cortical deformations and abnormal distribution of actomyosin regulators. Inhibiting moesin activation also impaired microtubule organization and precluded stable positioning of the mitotic spindle. We propose that the spatiotemporal control of moesin activation at the mitotic cortex provides localized cues to coordinate cortical contractility and microtubule interactions during cell division.

scholarly journals Investigations in vitro on the behaviour of chromosomes and the mitotic apparatus in endosperm cells of Haemanthus katherinae Baker treated with oleander glycosides

2015 ◽  
Vol 45 (3) ◽  
pp. 271-283
Author(s):  
J. A. Tarkowska
Keyword(s):  
Cell Division ◽  
Mitotic Spindle ◽  
Strong Tendency ◽  
Mitotic Apparatus ◽  
Meristematic Cells ◽  
Root Meristematic Cells ◽  
Chromosome Pattern ◽  
Chromosome Movements

The effect of oleander glycosides on dividing endosperm cells of <i>Haemanthus katherine</i> was investigated in vitro. The disturbances in the successive cell division phases were analysed in reference to cytokinesis. A strong tendency was noted to restitution nuclei formation in all phases of mitosis, and particularly in prophase. The observed chromosome pattern is the result of disturbances in prometaphase and anaphase chromosome movements owing to disturbances in the function of 'the 'mitotic spindle. It is probable that oleander glycosides inhibit formatiom of 'the microtubules of the mitotic spindle and disorganize the already formed spindle. They cause minor disturbances in cytokinesis, although frequently cell plates arise in quite unexpected places. The results of the present study are compared with those obtained in the case of root meristematic cells (Tarkowska, 1971a, b).

Mitotic spindle morphogenesis: Ran on the microtubule cytoskeleton and beyond

2006 ◽  
Vol 34 (5) ◽  
pp. 716-721 ◽  
Author(s):  
B. Goodman ◽  
Y. Zheng
Keyword(s):  
Cell Division ◽  
Chromosome Segregation ◽  
Mitotic Spindle ◽  
Spindle Assembly ◽  
Microtubule Assembly ◽  
Microtubule Organization ◽  
Spindle Matrix ◽  
Small G Protein ◽  
Important Regulator

Assembly and disassembly of the mitotic spindle are essential for both chromosome segregation and cell division. The small G-protein Ran has emerged as an important regulator of spindle assembly. In this review, we look at the role of Ran in different aspects of spindle assembly, including its effects on microtubule assembly dynamics and microtubule organization. In addition, we examine the possibility of a spindle matrix and the role Ran might play in such a structure.

scholarly journals Pericentromere tension is self-regulated by spindle structure in metaphase

2014 ◽  
Vol 205 (3) ◽  
pp. 313-324 ◽  
Author(s):  
Jeremy M. Chacón ◽  
Soumya Mukherjee ◽  
Breanna M. Schuster ◽  
Duncan J. Clarke ◽  
Melissa K. Gardner
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Division ◽  
Chromosome Segregation ◽  
Mitotic Spindle ◽  
Chromosome Structure ◽  
Wild Type ◽  
Checkpoint Signaling ◽  
Daughter Cells ◽  
Fluorescent Markers ◽  
Spindle Structure

During cell division, a mitotic spindle is built by the cell and acts to align and stretch duplicated sister chromosomes before their ultimate segregation into daughter cells. Stretching of the pericentromeric chromatin during metaphase is thought to generate a tension-based signal that promotes proper chromosome segregation. However, it is not known whether the mitotic spindle actively maintains a set point tension magnitude for properly attached sister chromosomes to facilitate robust mechanochemical checkpoint signaling. By imaging and tracking the thermal movements of pericentromeric fluorescent markers in Saccharomyces cerevisiae, we measured pericentromere stiffness and then used the stiffness measurements to quantitatively evaluate the tension generated by pericentromere stretch during metaphase in wild-type cells and in mutants with disrupted chromosome structure. We found that pericentromere tension in yeast is substantial (4–6 pN) and is tightly self-regulated by the mitotic spindle: through adjustments in spindle structure, the cell maintains wild-type tension magnitudes even when pericentromere stiffness is disrupted.

scholarly journals Modelling chromosome dynamics in mitosis: a historical perspective on models of metaphase and anaphase in eukaryotic cells

2014 ◽  
Vol 4 (3) ◽  
pp. 20130073 ◽  
Author(s):  
Gul Civelekoglu-Scholey ◽  
Daniela Cimini
Keyword(s):  
Cell Division ◽  
Mitotic Spindle ◽  
Historical Perspective ◽  
Quantitative Modelling ◽  
Mitotic Apparatus ◽  
Form Of Life ◽  
Daughter Cells ◽  
The Past ◽  
Quantitative Understanding ◽  
Spindle Elongation

Mitosis is the process by which the genome is segregated to form two identical daughter cells during cell division. The process of cell division is essential to the maintenance of every form of life. However, a detailed quantitative understanding of mitosis has been difficult owing to the complexity of the process. Indeed, it has been long recognized that, because of the complexity of the molecules involved, their dynamics and their properties, the mitotic events that mediate the segregation of the genome into daughter nuclei cannot be fully understood without the contribution of mathematical/quantitative modelling. Here, we provide an overview of mitosis and describe the dynamic and mechanical properties of the mitotic apparatus. We then discuss several quantitative models that emerged in the past decades and made an impact on our understanding of specific aspects of mitosis, including the motility of the chromosomes within the mitotic spindle during metaphase and anaphase, the maintenance of spindle length during metaphase and the switch to spindle elongation that occurs during anaphase.

scholarly journals A new piece in the kinetochore jigsaw puzzle

2014 ◽  
Vol 206 (4) ◽  
pp. 457-459
Author(s):  
Kevin D. Corbett ◽  
Arshad Desai
Keyword(s):  
Cell Division ◽  
Signaling Pathways ◽  
Chromosome Segregation ◽  
Budding Yeast ◽  
Eukaryotic Cell ◽  
Jigsaw Puzzle ◽  
New Model ◽  
Cell Biol ◽  
Chromosome Attachment ◽  
Spindle Microtubules

In eukaryotic cell division, the kinetochore mediates chromosome attachment to spindle microtubules and acts as a scaffold for signaling pathways, ensuring the accuracy of chromosome segregation. The architecture of the kinetochore underlies its function in mitosis. In this issue, Hornung et al. (2014. J. Cell Biol. http://dx.doi.org/201403081) identify an unexpected linkage between the inner and outer regions of the kinetochore in budding yeast that suggests a new model for the construction of this interface.

scholarly journals Aurora A Protein Kinase: To the Centrosome and Beyond

Biomolecules ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 28 ◽  
Author(s):  
Laura Magnaghi-Jaulin ◽  
Grégory Eot-Houllier ◽  
Emmanuel Gallaud ◽  
Régis Giet
Keyword(s):  
Cell Division ◽  
Protein Kinase ◽  
Chromosome Segregation ◽  
Mitotic Spindle ◽  
Aurora A ◽  
Cellular Cytoskeleton ◽  
Cytoskeletal Rearrangements ◽  
Centromeric Proteins

Accurate chromosome segregation requires the perfect spatiotemporal rearrangement of the cellular cytoskeleton. Isolated more than two decades ago from Drosophila, Aurora A is a widespread protein kinase that plays key roles during cell division. Numerous studies have described the localisation of Aurora A at centrosomes, the mitotic spindle, and, more recently, at mitotic centromeres. In this review, we will summarise the cytoskeletal rearrangements regulated by Aurora A during cell division. We will also discuss the recent discoveries showing that Aurora A also controls not only the dynamics of the cortical proteins but also regulates the centromeric proteins, revealing new roles for this kinase during cell division.

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.

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