bims-micesi Biomed News
on Mitotic cell signalling
Issue of 2023–02–12
ten papers selected by
Valentina Piano, Uniklinik Köln
  1. Mitosis: Augmin-based bridges keep kinetochores in line.
  2. The importance of microtubule-dependent tension in accurate chromosome segregation.
  3. Assessment of Spindle Shape Control by Spindle Poleward Flux Measurements and FRAP Bulk Analysis.
  4. RNA localization to the mitotic spindle is essential for early development and is regulated by kinesin-1 and dynein.
  5. The ancestral mitotic state: Closed orthomitosis with intranuclear spindles in the syncytial last eukaryotic common ancestor.
  6. SH2D4A promotes centrosome maturation to support spindle microtubule formation and mitotic progression.
  7. The cryo-EM structure of the CENP-A nucleosome in complex with ggKNL2.
  8. Aurora B SUMOylation Is Restricted to Centromeres in Early Mitosis and Requires RANBP2.
  9. Cell cycle-dependent palmitoylation of protocadherin 7 by ZDHHC5 promotes successful cytokinesis.
  10. Polarized branched Actin modulates cortical mechanics to produce unequal-size daughters during asymmetric division.
  1. Curr Biol. 2023 Feb 06. pii: S0960-9822(22)01974-1. [Epub ahead of print]33(3): R118-R121
    Mitosis: Augmin-based bridges keep kinetochores in line.
    Marcus A Begley, Mary Williard Elting.
      A recent study highlights the indispensability of the augmin complex for the construction of mitotic spindle bridging fibers, which in turn support accurate chromosome attachment and segregation.
    DOI:  https://doi.org/10.1016/j.cub.2022.12.037
  2. Front Cell Dev Biol. 2023 ;11 1096333
    The importance of microtubule-dependent tension in accurate chromosome segregation.
    Angela R Bunning, Mohan L Gupta.
      Accurate chromosome segregation is vital for cell and organismal viability. The mitotic spindle, a bipolar macromolecular machine composed largely of dynamic microtubules, is responsible for chromosome segregation during each cell replication cycle. Prior to anaphase, a bipolar metaphase spindle must be formed in which each pair of chromatids is attached to microtubules from opposite spindle poles. In this bipolar configuration pulling forces from the dynamic microtubules can generate tension across the sister kinetochores. The tension status acts as a signal that can destabilize aberrant kinetochore-microtubule attachments and reinforces correct, bipolar connections. Historically it has been challenging to isolate the specific role of tension in mitotic processes due to the interdependency of attachment and tension status at kinetochores. Recent technical and experimental advances have revealed new insights into how tension functions during mitosis. Here we summarize the evidence that tension serves as a biophysical signal that unifies multiple aspects of kinetochore and centromere function to ensure accurate chromosome segregation.
    Keywords:  chromosome segregation; kinetochore; microtubule; spindle checkpoint; tension
    DOI:  https://doi.org/10.3389/fcell.2023.1096333
  3. Methods Mol Biol. 2023 ;2604 113-125
    Assessment of Spindle Shape Control by Spindle Poleward Flux Measurements and FRAP Bulk Analysis.
    Sabine Müller.
      In plants, the segregation of genetic material is achieved by an acentrosomal, mitotic spindle. This macromolecular machinery consists of different microtubule subpopulations and interacting proteins. The majority of what we know about the assembly and shape control of the mitotic spindle arose from vertebrate model systems. The dynamic properties of the individual tubulin polymers are crucial for the accurate assembly of the spindle array and are modulated by microtubule-associated motor and non-motor proteins. The mitotic spindle relies on a phenomenon called poleward microtubule flux that is critical to establish spindle shape, chromosome alignment, and segregation. This flux is under control of the non-motor microtubule-associated proteins and force-generating motors. Despite the large number of (plant-specific) kinesin motor proteins expressed during mitosis, their mitotic roles remain largely elusive. Moreover, reports on mitotic spindle formation and shape control in higher plants are scarce. In this chapter, an overview of the basic principles and methods concerning live imaging of prometa- and metaphase spindles and the analysis of spindle microtubule flux using fluorescence recovery after photobleaching is provided.
    Keywords:  Arabidopsis; CLSM; Cell division; Fluorescence recovery after photobleaching; Kymograph; Microtubule dynamics; Poleward flux; Spindle
    DOI:  https://doi.org/10.1007/978-1-0716-2867-6_9
  4. J Cell Sci. 2023 Feb 08. pii: jcs.260528. [Epub ahead of print]
    RNA localization to the mitotic spindle is essential for early development and is regulated by kinesin-1 and dynein.
    Carolyn M Remsburg, Kalin D Konrad, Jia L Song.
      Mitosis is a fundamental and highly regulated process that acts to faithfully segregate chromosomes into two identical daughter cells. Transcript localization of genes involved in mitosis to the mitotic spindle may be an evolutionarily conserved mechanism to ensure that mitosis occurs in a timely manner. We identified many RNA transcripts that encode proteins involved in mitosis localized at the mitotic spindles in dividing sea urchin embryos and mammalian cells. Disruption of microtubule polymerization, kinesin-1, or dynein results in lack of spindle localization of these transcripts in the sea urchin embryo. Further, results indicate that the cytoplasmic polyadenylation element (CPE) within the 3'UTR of Aurora B, a recognition sequence of CPEB, is essential for RNA localization to the mitotic spindle. Blocking this sequence results in arrested development during early cleavage stages, suggesting that RNA localization to the mitotic spindle may be a regulatory mechanism of cell division that is important for early development.
    Keywords:  Dynein; Embryonic development; Kinesin-1; Mitosis; RNA localization
    DOI:  https://doi.org/10.1242/jcs.260528
  5. Genome Biol Evol. 2023 Feb 08. pii: evad016. [Epub ahead of print]
    The ancestral mitotic state: Closed orthomitosis with intranuclear spindles in the syncytial last eukaryotic common ancestor.
    Nico Bremer, Fernando D K Tria, Josip Skejo, William F Martin.
      All eukaryotes have linear chromosomes that are distributed to daughter nuclei during mitotic division, but the ancestral state of nuclear division in the last eukaryotic common ancestor (LECA) is so far unresolved. To address this issue, we have employed ancestral state reconstructions (ASR) for mitotic states that can be found across the eukaryotic tree concerning the intactness of the nuclear envelope during mitosis (open or closed), the position of spindles (intranuclear or extranuclear), and the symmetry of spindles being either axial (orthomitosis) or bilateral (pleuromitosis). The data indicate that the last eukaryotic common ancestor possessed closed orthomitosis with intranuclear spindles. Our reconstruction is compatible with recent findings indicating a syncytial state of the last eukaryotic common ancestor, because it decouples three main processes: chromosome division, chromosome partitioning and cell division (cytokinesis). The possession of closed mitosis using intranuclear spindles adds to the number of cellular traits that can now be attributed to LECA, providing insights into the lifestyle of this otherwise elusive biological entity at the origin of eukaryotic cells. Closed mitosis in a syncytial eukaryotic common ancestor would buffer mutations arising at the origin of mitotic division by allowing nuclei with viable chromosome sets to complement defective nuclei via mRNA in the cytosol.
    Keywords:  ancestral state reconstruction; eukaryogenesis; last eukaryotic common ancestor; mitosis; syncytium
    DOI:  https://doi.org/10.1093/gbe/evad016
  6. Sci Rep. 2023 Feb 04. 13(1): 2067
    SH2D4A promotes centrosome maturation to support spindle microtubule formation and mitotic progression.
    Ryuzaburo Yuki, Yuki Ikeda, Ryuji Yasutake, Youhei Saito, Yuji Nakayama.
      Mitotic progression requires the precise formation of spindle microtubules based on mature centrosomes. During the G2/M transition, centrosome maturation progresses, and associated microtubules bundle to form mitotic spindle fibers and capture the chromosomes for alignment at the cell equator. Mitotic kinases-induced phosphorylation signaling is necessary for these processes. Here, we identified SH2 domain-containing protein 4A (SH2D4A/PPP1R38) as a new mitotic regulator. SH2D4A knockdown delays mitotic progression. The time-lapse imaging analysis showed that SH2D4A specifically contributes to the alignment of chromosomes. The cold treatment assay and microtubule regrowth assay indicated that SH2D4A promotes microtubule nucleation to support kinetochore-microtubule attachment. This may be due to the centrosome maturation by SH2D4A via centrosomal recruitment of pericentriolar material (PCM) such as cep192, γ-tubulin, and PLK1. SH2D4A was found to be a negative regulator of PP1 phosphatase. Consistently, treatment with a PP1 inhibitor rescues SH2D4A-knockdown-induced phenotypes, including the microtubule nucleation and centrosomal recruitment of active PLK1. These results suggest that SH2D4A is involved in PCM recruitment to centrosomes and centrosome maturation through attenuation of PP1 phosphatases, accelerating the spindle formation and supporting mitotic progression.
    DOI:  https://doi.org/10.1038/s41598-023-29362-w
  7. EMBO J. 2023 Feb 06. e111965
    The cryo-EM structure of the CENP-A nucleosome in complex with ggKNL2.
    Honghui Jiang, Mariko Ariyoshi, Tetsuya Hori, Reito Watanabe, Fumiaki Makino, Keiichi Namba, Tatsuo Fukagawa.
      Centromere protein A (CENP-A) nucleosomes containing the centromere-specific histone H3 variant CENP-A represent an epigenetic mark that specifies centromere position. The Mis18 complex is a licensing factor for new CENP-A deposition via the CENP-A chaperone, Holliday junction recognition protein (HJURP), on the centromere chromatin. Chicken KINETOCHORE NULL2 (KNL2) (ggKNL2), a Mis18 complex component, has a CENP-C-like motif, and our previous study suggested that ggKNL2 directly binds to the CENP-A nucleosome to recruit HJURP/CENP-A to the centromere. However, the molecular basis for CENP-A nucleosome recognition by ggKNL2 has remained unclear. Here, we present the cryo-EM structure of the chicken CENP-A nucleosome in complex with a ggKNL2 fragment containing the CENP-C-like motif. Chicken KNL2 distinguishes between CENP-A and histone H3 in the nucleosome using the CENP-C-like motif and its downstream region. Both the C-terminal tail and the RG-loop of CENP-A are simultaneously recognized as CENP-A characteristics. The CENP-A nucleosome-ggKNL2 interaction is thus essential for KNL2 functions. Furthermore, our structural, biochemical, and cell biology data indicate that ggKNL2 changes its binding partner at the centromere during chicken cell cycle progression.
    Keywords:  CENP-A; CENP-C-like motif; Cryo-EM; KNL2
    DOI:  https://doi.org/10.15252/embj.2022111965
  8. Cells. 2023 Jan 19. pii: 372. [Epub ahead of print]12(3):
    Aurora B SUMOylation Is Restricted to Centromeres in Early Mitosis and Requires RANBP2.
    Erica Di Cesare, Sara Moroni, Jessica Bartoli, Michela Damizia, Maria Giubettini, Carolin Koerner, Veronica Krenn, Andrea Musacchio, Patrizia Lavia.
      Conjugation with the small ubiquitin-like modifier (SUMO) modulates protein interactions and localisation. The kinase Aurora B, a key regulator of mitosis, was previously identified as a SUMOylation target in vitro and in assays with overexpressed components. However, where and when this modification genuinely occurs in human cells was not ascertained. Here, we have developed intramolecular Proximity Ligation Assays (PLA) to visualise SUMO-conjugated Aurora B in human cells in situ. We visualised Aurora B-SUMO products at centromeres in prometaphase and metaphase, which declined from anaphase onwards and became virtually undetectable at cytokinesis. In the mitotic window in which Aurora B/SUMO products are abundant, Aurora B co-localised and interacted with NUP358/RANBP2, a nucleoporin with SUMO ligase and SUMO-stabilising activity. Indeed, in addition to the requirement for the previously identified PIAS3 SUMO ligase, we found that NUP358/RANBP2 is also implicated in Aurora B-SUMO PLA product formation and centromere localisation. In summary, SUMOylation marks a distinctive window of Aurora B functions at centromeres in prometaphase and metaphase while being dispensable for functions exerted in cytokinesis, and RANBP2 contributes to this control, adding a novel layer to modulation of Aurora B functions during mitosis.
    Keywords:  Aurora B; RANBP2; SUMOylation; in situ proximity ligation assay (isPLA); mitosis
    DOI:  https://doi.org/10.3390/cells12030372
  9. J Cell Sci. 2023 Feb 10. pii: jcs.260266. [Epub ahead of print]
    Cell cycle-dependent palmitoylation of protocadherin 7 by ZDHHC5 promotes successful cytokinesis.
    Nazlı Ezgi Ozkan Kucuk, Berfu Nur Yigit, Beste Senem Degirmenci, Mohammad Haroon Qureshi, Gamze Nur Yapici, Altuğ Kamacıoglu, Nima Bavili, Alper Kiraz, Nurhan Ozlu.
      Cell division requires dramatic reorganization of the cell cortex which is primarily driven by the actomyosin network. We previously reported that Protocadherin 7 (PCDH7) gets enriched at the cell surface during mitosis which is required to build up the full mitotic rounding pressure. Here we report that PCDH7 interacts with, and is palmitoylated by the palmitoyltransferase, ZDHHC5. Both PCDH7 and ZDHHC5 co-localize at the mitotic cell surface, and translocate to the cleavage furrow during cytokinesis. PCDH7's localization depends on the palmitoylation activity of ZDHHC5. Silencing PCDH7 increases the percentage of multinucleated cells and the duration of mitosis. Loss of PCDH7 expression correlates with reduced levels of active RhoA and phospho-myosin at the cleavage furrow. This work uncovers a palmitoylation-dependent translocation mechanism for PCDH7 which contributes to the reorganization of the cortical cytoskeleton during cell division.
    Keywords:  Actomyosin; BioID; Cleavage furrow; Cytokinesis; Mitosis; PCDH7; Palmitoylation; Plasma Membrane; Plasticity; Protocadherin; ZDHHC5
    DOI:  https://doi.org/10.1242/jcs.260266
  10. Nat Cell Biol. 2023 Feb 06.
    Polarized branched Actin modulates cortical mechanics to produce unequal-size daughters during asymmetric division.
    Alicia Daeden, Alexander Mietke, Emmanuel Derivery, Carole Seum, Frank Jülicher, Marcos Gonzalez-Gaitan.
      The control of cell shape during cytokinesis requires a precise regulation of mechanical properties of the cell cortex. Only few studies have addressed the mechanisms underlying the robust production of unequal-sized daughters during asymmetric cell division. Here we report that unequal daughter-cell sizes resulting from asymmetric sensory organ precursor divisions in Drosophila are controlled by the relative amount of cortical branched Actin between the two cell poles. We demonstrate this by mistargeting the machinery for branched Actin dynamics using nanobodies and optogenetics. We can thereby engineer the cell shape with temporal precision and thus the daughter-cell size at different stages of cytokinesis. Most strikingly, inverting cortical Actin asymmetry causes an inversion of daughter-cell sizes. Our findings uncover the physical mechanism by which the sensory organ precursor mother cell controls relative daughter-cell size: polarized cortical Actin modulates the cortical bending rigidity to set the cell surface curvature, stabilize the division and ultimately lead to unequal daughter-cell size.
    DOI:  https://doi.org/10.1038/s41556-022-01058-9
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