bims-micesi Biomed News
on Mitotic cell signalling
Issue of 2023–11–05
six papers selected by
Valentina Piano, Uniklinik Köln
  1. Chromosome size-dependent polar ejection force impairs mammalian mitotic error correction.
  2. Serial-section Electron Tomography and Quantitative Analysis of Microtubule Organization in 3D-reconstructed Mitotic Spindles.
  3. Quantifying the large-scale chromosome structural dynamics during the mitosis-to-G1 phase transition of cell cycle.
  4. An antioxidant screen identifies ascorbic acid for prevention of light-induced mitotic prolongation in live cell imaging.
  5. The Aurora kinase B relocation blocker LXY18 triggers mitotic catastrophe selectively in malignant cells.
  6. Chromosome instability and aneuploidy in the mammalian brain.
  1. bioRxiv. 2023 Oct 18. pii: 2023.10.16.562637. [Epub ahead of print]
    Chromosome size-dependent polar ejection force impairs mammalian mitotic error correction.
    Megan K Chong, Miquel Rosas-Salvans, Vanna Tran, Sophie Dumont.
      Accurate chromosome segregation requires sister kinetochores to biorient, attaching to opposite spindle poles. To this end, the mammalian kinetochore destabilizes incorrect attachments and stabilizes correct ones, but how it discriminates between these is not yet clear. Here, we test the model that kinetochore tension is the stabilizing cue and ask how chromosome size impacts that model. We live image PtK2 cells, with just 14 chromosomes, widely ranging in size, and find that long chromosomes align at the metaphase plate later than short chromosomes. Enriching for errors and imaging error correction live, we show that long chromosomes exhibit a specific delay in correcting attachments. Using chromokinesin overexpression and laser ablation to perturb polar ejection forces, we find that chromosome size and force on arms determine alignment order. Thus, we propose a model where increased force on long chromosomes can falsely stabilize incorrect attachments, delaying their biorientation. As such, long chromosomes may require compensatory mechanisms for correcting errors to avoid chromosomal instability.
    DOI:  https://doi.org/10.1101/2023.10.16.562637
  2. Bio Protoc. 2023 Oct 20. 13(20): e4849
    Serial-section Electron Tomography and Quantitative Analysis of Microtubule Organization in 3D-reconstructed Mitotic Spindles.
    Robert Kiewisz, Daniel Baum, Thomas Müller-Reichert, Gunar Fabig.
      For the analysis of cellular architecture during mitosis, nanometer resolution is needed to visualize the organization of microtubules in spindles. Here, we present a detailed protocol that can be used to produce 3D reconstructions of whole mitotic spindles in cells grown in culture. For this, we attach mammalian cells enriched in mitotic stages to sapphire discs. Our protocol further involves cryo-immobilization by high-pressure freezing, freeze-substitution, and resin embedding. We then use fluorescence light microscopy to stage select mitotic cells in the resin-embedded samples. This is followed by large-scale electron tomography to reconstruct the selected and staged mitotic spindles in 3D. The generated and stitched electron tomograms are then used to semi-automatically segment the microtubules for subsequent quantitative analysis of spindle organization. Thus, by providing a detailed correlative light and electron microscopy (CLEM) approach, we give cell biologists a toolset to streamline the 3D visualization and analysis of spindle microtubules (http://kiewisz.shinyapps.io/asga). In addition, we refer to a recently launched platform that allows for an interactive display of the 3D-reconstructed mitotic spindles (https://cfci.shinyapps.io/ASGA_3DViewer/). Key features • High-throughput screening of mitotic cells by correlative light and electron microscopy (CLEM). • Serial-section electron tomography of selected cells. • Visualization of mitotic spindles in 3D and quantitative analysis of microtubule organization.
    Keywords:  3D reconstruction; Automated spatial graph analysis; Automatic segmentation of microtubules; CLEM; Correlative light and electron microscopy; Electron microscopy; Electron tomography; HeLa cells; Human cells; Microtubules; Mitotic spindle; Serial sectioning; Tissue culture cells
    DOI:  https://doi.org/10.21769/BioProtoc.4849
  3. Open Biol. 2023 Nov;13(11): 230175
    Quantifying the large-scale chromosome structural dynamics during the mitosis-to-G1 phase transition of cell cycle.
    Xiakun Chu, Jin Wang.
      Cell cycle is known to be regulated by the underlying gene network. Chromosomes, which serve as the scaffold for gene expressions, undergo significant structural reorganizations during mitosis. Understanding the mechanism of the cell cycle from the chromosome structural perspective remains a grand challenge. In this study, we applied an integrated theoretical approach to investigate large-scale chromosome structural dynamics during the mitosis-to-G1 phase transition. We observed that the chromosome structural expansion and adaptation of the structural asphericity do not occur synchronously and attributed this behaviour to the unique unloading sequence of the two types of condensins. Furthermore, we observed that the coherent motions between the chromosomal loci are primarily enhanced within the topologically associating domains (TADs) as cells progress to the G1 phase, suggesting that TADs can be considered as both structural and dynamical units for organizing the three-dimensional chromosome. Our analysis also reveals that the quantified pathways of chromosome structural reorganization during the mitosis-to-G1 phase transition exhibit high stochasticity at the single-cell level and show nonlinear behaviours in changing TADs and contacts formed at the long-range regions. Our findings offer valuable insights into large-scale chromosome structural dynamics after mitosis.
    Keywords:  cell cycle; chromosome structural reorganizations; coarse-grained model; energy landscape; four-dimensional genome modelling; three-dimensional genome
    DOI:  https://doi.org/10.1098/rsob.230175
  4. Commun Biol. 2023 Nov 01. 6(1): 1107
    An antioxidant screen identifies ascorbic acid for prevention of light-induced mitotic prolongation in live cell imaging.
    Tomoki Harada, Shoji Hata, Rioka Takagi, Takuma Komori, Masamitsu Fukuyama, Takumi Chinen, Daiju Kitagawa.
      Phototoxicity is an important issue in fluorescence live imaging of light-sensitive cellular processes such as mitosis. Among several approaches to reduce phototoxicity, the addition of antioxidants to the media has been used as a simple method. Here, we analyzed the impact of phototoxicity on the mitotic progression in fluorescence live imaging of human cells and performed a screen to identify the most efficient antioxidative agents that reduce it. Quantitative analysis shows that high amounts of light illumination cause various mitotic defects such as prolonged mitosis and delays of chromosome alignment and centrosome separation. Among several antioxidants, our screen reveals that ascorbic acid significantly alleviates these phototoxic effects in mitosis. Furthermore, we demonstrate that adding ascorbic acid to the media enables fluorescence imaging of mitotic events at very high temporal resolution without obvious photodamage. Thus, this study provides an optimal method to effectively reduce the phototoxic effects in fluorescence live cell imaging.
    DOI:  https://doi.org/10.1038/s42003-023-05479-6
  5. PLoS One. 2023 ;18(10): e0293283
    The Aurora kinase B relocation blocker LXY18 triggers mitotic catastrophe selectively in malignant cells.
    Julia Kalashova, Chenglu Yang, Hongmei Li, Yan Long, Duo Yu, Ting Zhang, Xumei Liu, Namrta Choudhry, Qiong Shi, Thaddeus D Allen.
      The mitotic regulator, Aurora kinase B (AURKB), is frequently overexpressed in malignancy and is a target for therapeutic intervention. The compound, LXY18, is a potent, orally available small molecule that inhibits the proper localization of AURKB during late mitosis, without affecting its kinase activity. In this study, we demonstrate that LXY18 elicits apoptosis in cancer cells derived from various indications, but not in non-transformed cell lines. The apoptosis is p53-independent, triggered by a prolonged mitotic arrest and occurs predominantly in mitosis. Some additional cells succumb post-mitotic slippage. We also demonstrate that cancer cell lines refractory to AURKB kinase inhibitors are sensitive to LXY18. The mitotic proteins MKLP2, NEK6, NEK7 and NEK9 are known regulators of AURKB localization during the onset of anaphase. LXY18 fails to inhibit the catalytic activity of these AURKB localization factors. Overall, our findings suggest a novel activity for LXY18 that produces a prolonged mitotic arrest and lethality in cancer cells, leaving non-transformed cells healthy. This new activity suggests that the compound may be a promising drug candidate for cancer treatment and that it can also be used as a tool compound to further dissect the regulatory network controlling AURKB localization.
    DOI:  https://doi.org/10.1371/journal.pone.0293283
  6. Chromosome Res. 2023 Nov 01. 31(4): 32
    Chromosome instability and aneuploidy in the mammalian brain.
    Olivia Albert, Shixiang Sun, Anita Huttner, Zhengdong Zhang, Yousin Suh, Judith Campisi, Jan Vijg, Cristina Montagna.
      This review investigates the role of aneuploidy and chromosome instability (CIN) in the aging brain. Aneuploidy refers to an abnormal chromosomal count, deviating from the normal diploid set. It can manifest as either a deficiency or excess of chromosomes. CIN encompasses a broader range of chromosomal alterations, including aneuploidy as well as structural modifications in DNA. We provide an overview of the state-of-the-art methodologies utilized for studying aneuploidy and CIN in non-tumor somatic tissues devoid of clonally expanded populations of aneuploid cells.CIN and aneuploidy, well-established hallmarks of cancer cells, are also associated with the aging process. In non-transformed cells, aneuploidy can contribute to functional impairment and developmental disorders. Despite the importance of understanding the prevalence and specific consequences of aneuploidy and CIN in the aging brain, these aspects remain incompletely understood, emphasizing the need for further scientific investigations.This comprehensive review consolidates the present understanding, addresses discrepancies in the literature, and provides valuable insights for future research efforts.
    Keywords:  Aging; Aneuploidy; Astrocytes; Brain; Cancer; Chromosome instability; Copy number alterations; Disease; Genomic instability; Glioblastoma; Mutation frequency; Mutations; Neurodegeneration; Neurons; Tumor
    DOI:  https://doi.org/10.1007/s10577-023-09740-w
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