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Seminars in Cell & Developmental Biology Sep 2021Mitotic cell divisions ensure stable transmission of genetic information from a mother to daughter cells in a series of generations. To ensure this crucial task is... (Review)
Review
Mitotic cell divisions ensure stable transmission of genetic information from a mother to daughter cells in a series of generations. To ensure this crucial task is accomplished, the cell forms a bipolar structure called the mitotic spindle that divides sister chromatids to the opposite sides of the dividing mother cell. After successful establishment of stable attachments of microtubules to chromosomes and inspection of connections between them, at the heart of mitosis, the cell starts the process of segregation. This spectacular moment in the life of a cell is termed anaphase, and it involves two distinct processes: depolymerization of microtubules bound to chromosomes, which is also known as anaphase A, and elongation of the spindle or anaphase B. Both processes ensure physical separation of disjointed sister chromatids. In this chapter, we review the mechanisms of anaphase B spindle elongation primarily in mammalian systems, combining different pioneering ideas and concepts with more recent findings that shed new light on the force generation and regulation of biochemical modules operating during spindle elongation. Finally, we present a comprehensive model of spindle elongation that includes structural, biophysical, and molecular aspects of anaphase B.
Topics: Anaphase; Chromosome Segregation; Humans; Microtubules
PubMed: 33849764
DOI: 10.1016/j.semcdb.2021.03.023 -
Frontiers in Cell and Developmental... 2023Cell division events require regulatory systems to ensure that events happen in a distinct order. The classic view of temporal control of the cell cycle posits that... (Review)
Review
Cell division events require regulatory systems to ensure that events happen in a distinct order. The classic view of temporal control of the cell cycle posits that cells order events by linking them to changes in Cyclin Dependent Kinase (CDK) activities. However, a new paradigm is emerging from studies of anaphase where chromatids separate at the central metaphase plate and then move to opposite poles of the cell. These studies suggest that distinct events are ordered depending upon the location of each chromosome along its journey from the central metaphase plate to the elongated spindle poles. This system is dependent upon a gradient of Aurora B kinase activity that emerges during anaphase and acts as a spatial beacon to control numerous anaphase/telophase events and cytokinesis. Recent studies also suggest that Aurora A kinase activity specifies proximity of chromosomes or proteins to spindle poles during prometaphase. Together these studies argue that a key role for Aurora kinases is to provide spatial information that controls events depending upon the location of chromosomes or proteins along the mitotic spindle.
PubMed: 36994100
DOI: 10.3389/fcell.2023.1139367 -
Mathematical Biosciences May 2024This paper develops a theory for anaphase in cells. After a brief description of microtubules, the mitotic spindle and the centrosome, a mathematical model for anaphase...
This paper develops a theory for anaphase in cells. After a brief description of microtubules, the mitotic spindle and the centrosome, a mathematical model for anaphase is introduced and developed in the context of the cell cytoplasm and liquid crystalline structures. Prophase, prometaphase and metaphase are then briefly described in order to focus on anaphase, which is the main study of this paper. The entities involved are modelled in terms of liquid crystal defects and microtubules are represented as defect flux lines. The mathematical techniques employed make extensive use of energy considerations based on the work that was developed by Dafermos (1970) from the classical Frank-Oseen nematic liquid crystal energy (Frank, 1958; Oseen, 1933). With regard to liquid crystal theory we introduce the concept of regions of influence for defects which it is believed have important implications beyond the subject of this paper. The results of this paper align with observed biochemical phenomena and are explored in application to HeLa cells and Caenorhabditis elegans. This unified approach offers the possibility of gaining insight into various consequences of mitotic abnormalities which may result in Down syndrome, Hodgkin lymphoma, breast, prostate and various other types of cancer.
PubMed: 38795952
DOI: 10.1016/j.mbs.2024.109219 -
Nature Metabolism Feb 2022Tumors can reprogram the functions of metabolic enzymes to fuel malignant growth; however, beyond their conventional functions, key metabolic enzymes have not been found...
Tumors can reprogram the functions of metabolic enzymes to fuel malignant growth; however, beyond their conventional functions, key metabolic enzymes have not been found to directly govern cell mitosis. Here, we report that glutamine synthetase (GS) promotes cell proliferation by licensing mitotic progression independently of its metabolic function. GS depletion, but not impairment of its enzymatic activity, results in mitotic arrest and multinucleation across multiple lung and liver cancer cell lines, patient-derived organoids and xenografted tumors. Mechanistically, GS directly interacts with the nuclear pore protein NUP88 to prevent its binding to CDC20. Such interaction licenses activation of the CDC20-mediated anaphase-promoting complex or cyclosome to ensure proper metaphase-to-anaphase transition. In addition, GS is overexpressed in human non-small cell lung cancer and its depletion reduces tumor growth in mice and increases the efficacy of microtubule-targeted chemotherapy. Our findings highlight a moonlighting function of GS in governing mitosis and illustrate how an essential metabolic enzyme promotes cell proliferation and tumor development, beyond its main metabolic function.
Topics: Animals; Carcinoma, Non-Small-Cell Lung; Cell Cycle Proteins; Cell Proliferation; Glutamate-Ammonia Ligase; Humans; Lung Neoplasms; Mice; Mitosis
PubMed: 35145325
DOI: 10.1038/s42255-021-00524-2 -
Cells Aug 2019Accurate division of cells into two daughters is a process that is vital to propagation of life. Protein phosphorylation and selective degradation have emerged as two... (Review)
Review
Accurate division of cells into two daughters is a process that is vital to propagation of life. Protein phosphorylation and selective degradation have emerged as two important mechanisms safeguarding the delicate choreography of mitosis. Protein phosphatases catalyze dephosphorylation of thousands of sites on proteins, steering the cells through establishment of the mitotic phase and exit from it. A large E3 ubiquitin ligase, the anaphase-promoting complex/cyclosome (APC/C) becomes active during latter stages of mitosis through G1 and marks hundreds of proteins for destruction. Recent studies have revealed the complex interregulation between these two classes of enzymes. In this review, we highlight the direct and indirect mechanisms by which phosphatases and the APC/C mutually influence each other to ensure accurate spatiotemporal and orderly progression through mitosis, with a particular focus on recent insights and conceptual advances.
Topics: Anaphase-Promoting Complex-Cyclosome; Animals; CDC2 Protein Kinase; Cell Line, Tumor; Humans; Mitosis; Phosphoric Monoester Hydrolases; Phosphorylation; Ubiquitination
PubMed: 31382469
DOI: 10.3390/cells8080814 -
Cells Oct 2022The midbody is an organelle that forms between the two daughter cells during cytokinesis. It co-ordinates the abscission of the nascent daughter cells and is composed of...
The midbody is an organelle that forms between the two daughter cells during cytokinesis. It co-ordinates the abscission of the nascent daughter cells and is composed of a multitude of proteins that are meticulously arranged into distinct temporal and spatial localization patterns. However, very little is known about the mechanisms that regulate the localization and function of midbody proteins. Here, we analyzed the temporal and spatial profiles of key midbody proteins during mitotic exit under normal conditions and after treatment with drugs that affect phosphorylation and proteasome-mediated degradation to decipher the impacts of post-translational modifications on midbody protein dynamics. Our results highlighted that midbody proteins show distinct spatio-temporal dynamics during mitotic exit and cytokinesis that depend on both ubiquitin-mediated proteasome degradation and phosphorylation/de-phosphorylation. They also identified two discrete classes of midbody proteins: 'transient' midbody proteins-including Anillin, Aurora B and PRC1-which rapidly accumulate at the midbody after anaphase onset and then slowly disappear, and 'stable' midbody proteins-including CIT-K, KIF14 and KIF23-which instead persist at the midbody throughout cytokinesis and also post abscission. These two classes of midbody proteins display distinct interaction networks with ubiquitylation factors, which could potentially explain their different dynamics and stability during cytokinesis.
Topics: Humans; Cytokinesis; HeLa Cells; Phosphorylation; Proteasome Endopeptidase Complex; Protein Serine-Threonine Kinases
PubMed: 36359734
DOI: 10.3390/cells11213337 -
Chromosoma Sep 2023Mitosis is an essential process in which the duplicated genome is segregated equally into two daughter cells. CTCF has been reported to be present in mitosis and has a...
Mitosis is an essential process in which the duplicated genome is segregated equally into two daughter cells. CTCF has been reported to be present in mitosis and has a role in localizing CENP-E, but its importance for mitotic fidelity remains to be determined. To evaluate the importance of CTCF in mitosis, we tracked mitotic behaviors in wild-type and two different CTCF CRISPR-based genetic knockdowns. We find that knockdown of CTCF results in prolonged mitoses and failed anaphase segregation via time-lapse imaging of SiR-DNA. CTCF knockdown did not alter cell cycling or the mitotic checkpoint, which was activated upon nocodazole treatment. Immunofluorescence imaging of the mitotic spindle in CTCF knockdowns revealed disorganization via tri/tetrapolar spindles and chromosomes behind the spindle pole. Imaging of interphase nuclei showed that nuclear size increased drastically, consistent with failure to divide the duplicated genome in anaphase. Long-term inhibition of CNEP-E via GSK923295 recapitulates CTCF knockdown abnormal mitotic spindles with polar chromosomes and increased nuclear sizes. Population measurements of nuclear shape in CTCF knockdowns do not display decreased circularity or increased nuclear blebbing relative to wild-type. However, failed mitoses do display abnormal nuclear morphologies relative to successful mitoses, suggesting that population images do not capture individual behaviors. Thus, CTCF is important for both proper metaphase organization and anaphase segregation which impacts the size and shape of the interphase nucleus likely through its known role in recruiting CENP-E.
PubMed: 37728741
DOI: 10.1007/s00412-023-00810-w -
Journal of Hematology & Oncology Nov 2019Mitosis is the process whereby an eukaryotic cell divides into two identical copies. Different multiprotein complexes are involved in the fine regulation of cell... (Review)
Review
Mitosis is the process whereby an eukaryotic cell divides into two identical copies. Different multiprotein complexes are involved in the fine regulation of cell division, including the mitotic promoting factor and the anaphase promoting complex. Prolonged mitosis can result in cellular division, cell death, or mitotic slippage, the latter leading to a new interphase without cellular division. Mitotic slippage is one of the causes of genomic instability and has an important therapeutic and clinical impact. It has been widely studied in solid tumors but not in hematological malignancies, in particular, in acute leukemia. We review the literature data available on mitotic regulation, alterations in mitotic proteins occurring in acute leukemia, induction of prolonged mitosis and its consequences, focusing in particular on the balance between cell death and mitotic slippage and on its therapeutic potentials. We also present the most recent preclinical and clinical data on the efficacy of second-generation mitotic drugs (CDK1-Cyclin B1, APC/CCDC20, PLK, Aurora kinase inhibitors). Despite the poor clinical activity showed by these drugs as single agents, they offer a potential therapeutic window for synthetic lethal combinations aimed to selectively target leukemic cells at the right time, thus decreasing the risk of mitotic slippage events.
Topics: Acute Disease; Antineoplastic Agents; Apoptosis; Cell Cycle Proteins; Genomic Instability; Humans; Leukemia; Mitosis; Neoplasm Proteins
PubMed: 31771633
DOI: 10.1186/s13045-019-0808-4 -
The EMBO Journal Mar 2024The efficacy of current antimitotic cancer drugs is limited by toxicity in highly proliferative healthy tissues. A cancer-specific dependency on the microtubule motor...
The efficacy of current antimitotic cancer drugs is limited by toxicity in highly proliferative healthy tissues. A cancer-specific dependency on the microtubule motor protein KIF18A therefore makes it an attractive therapeutic target. Not all cancers require KIF18A, however, and the determinants underlying this distinction remain unclear. Here, we show that KIF18A inhibition drives a modest and widespread increase in spindle assembly checkpoint (SAC) signaling from kinetochores which can result in lethal mitotic delays. Whether cells arrest in mitosis depends on the robustness of the metaphase-to-anaphase transition, and cells predisposed with weak basal anaphase-promoting complex/cyclosome (APC/C) activity and/or persistent SAC signaling through metaphase are uniquely sensitive to KIF18A inhibition. KIF18A-dependent cancer cells exhibit hallmarks of this SAC:APC/C imbalance, including a long metaphase-to-anaphase transition, and slow mitosis overall. Together, our data reveal vulnerabilities in the cell division apparatus of cancer cells that can be exploited for therapeutic benefit.
Topics: Humans; Anaphase-Promoting Complex-Cyclosome; Dyneins; Kinesins; Kinetochores; Mitosis; Neoplasms
PubMed: 38279026
DOI: 10.1038/s44318-024-00031-6 -
European Journal of Medical Genetics Feb 2020Genomic instability is widespread during early embryo development. Aneuploidy, mosaicism, and copy number variants (CNVs) commonly appear in human preimplantation... (Review)
Review
Genomic instability is widespread during early embryo development. Aneuploidy, mosaicism, and copy number variants (CNVs) commonly appear in human preimplantation embryos. Both age-dependent meiotic aneuploidy and age-independent mitotic aneuploidy and CNVs occur In human embryos. Telomere attrition, which contributes to genomic instability in somatic cells, also may promote genomic instability in preimplantation embryos. Telomere dynamics during gametogenesis are strikingly dimorphic between females and males. Sperm telomeres lengthen with advancing paternal age, while oocyte telomeres are among the shortest in the body. Spermatogonia express telomerase activity throughout the life of the male, while oocytes and cleavage stage embryos express low or un-measureable levels of telomerase activity. Telomere attrition in oocytes contributes to meiotic dysfunction, including spindle dysmorphologies, reduced synapsis and chiasmata, as well as delayed, arrested and fragmented embryos. Cleavage stage embryos, with such inefficient telomere reconstitution, likely undergo NHEJ, which produces anaphase lag, chromosome bridges, micronuclei, and genomic instability, including mosaicism and CNVs. Cleavage stage embryos reconstitute the short telomeres inherited from their mothers by Alternative Lengthening of Telomeres (ALT), a DNA recombination based method involving RAD 50, MRE 11, Werner and Bloom proteins, as well as telomere sister chromatid exchange. ALT robustly reconstitutes telomeres, but also predisposes to genomic instability.
Topics: Animals; Chromosome Aberrations; Embryonic Development; Genomic Instability; Humans; Oocytes; Recombination, Genetic; Telomere
PubMed: 30862510
DOI: 10.1016/j.ejmg.2019.03.002