bims-micesi Biomed News
on Mitotic cell signalling
Issue of 2025–04–27
eleven papers selected by
Valentina Piano, Uniklinik Köln
  1. Enhancement of CEP215/CDK5RAP2 dynamics for spindle pole assembly during mitosis.
  2. The centromere bottlebrush requires a multi-microtubule attachment.
  3. Preparation for mitosis requires gradual CDK1 activation.
  4. Regulation of microtubule growth rates and their impact on chromosomal instability.
  5. Protein Phosphatase 1 Regulatory Subunit PNUTS Prevents CENP-A Mislocalization and Chromosomal Instability.
  6. Centrosomes and cancer: balancing tumor-promoting and inhibitory roles.
  7. PLK4: Master Regulator of Centriole Duplication and Its Therapeutic Potential.
  8. Inactivation of the Catalytic Activity of Mps1 Kinase Prevents Its Own Degradation at Centrosomes.
  9. M-phase-specific generation of supernumerary centrioles in cancer cells.
  10. Nuclear Morphology-Based Assessment of Cell Fates Induced by a Microtubule Targeting Agent as a Single Treatment or Combined with an Oncolytic Virus.
  11. Mitochondrial fission surveillance is coupled to Caenorhabditis elegans DNA and chromosome segregation integrity.
  1. J Cell Sci. 2025 Apr 24. pii: jcs.263542. [Epub ahead of print]
    Enhancement of CEP215/CDK5RAP2 dynamics for spindle pole assembly during mitosis.
    Hyunjeong Yoo, Taehyun Kim, Sungjin Ryu, Donghee Ko, Jeesoo Kim, Hee-Jung Choi, Yongdae Shin, Kunsoo Rhee.
      The microtubule organizing activity of centrosomes fluctuates during the cell cycle, reaching the highest levels at M phase. CEP215/CDK5RAP2 is a key pericentriolar material (PCM) protein for microtubule organization of the human centrosome. Here, we provide evidence that CEP215 exhibits a dynamically suppressed, solid-like state in interphase centrosomes, and becomes a more dynamic state in mitotic centrosomes. Specific interaction with PCNT, another centrosome protein, is crucial for diffusible molecular dynamicity of the CEP215 protein. We also found that the cluster formation activity of CEP215 is impaired in a light-inducible system when its coiled-coil domains (CCDs) are truncated. Defects in spindle pole assembly and spindle formation were accompanied in the cells whose CEP215 is substituted with the CCD-truncated mutants. Our results support the notion that the diffusible mobility of CEP215 is enhanced by both homotypic and heterotypic interactions among CCDs, especially at mitotic spindle poles. This work highlights that biophysical properties of the PCM proteins at the centrosomes fluctuate during the cell cycle.
    Keywords:  CEP215/CDK5RAP2; Centrosome; Mitotic spindle; Pericentriolar material; Protein dynamics; Spindle pole
    DOI:  https://doi.org/10.1242/jcs.263542
  2. Mol Biol Cell. 2025 Apr 23. mbcE25020050
    The centromere bottlebrush requires a multi-microtubule attachment.
    Daniel Kolbin, John Stanton, Aryan Kokkanti, Elaine Yeh, Kerry Bloom.
      Pericentromeric bottlebrush converts DNA into a stiff spring through density and organization of loops relative to the mitotic spindle axis. This spring is integral to tension-sensing mechanisms required for faithful chromosome segregation. Cohesin enrichment is a hallmark of yeast pericentric loops.  We used haploid yeasts engineered to contain 2 instead of the normal 16 chromosomes to determine the number of centromeres required for cohesin loading to form a pericentric bottlebrush. In wildtype yeasts the mitotic spindle is 1.5 microns long and 16 centromeres appear in tight clusters. Cohesin surrounds the metaphase spindle forming a cylindrical barrel and crosslinking the radial array of chromatin loops. In the two-chromosome strain, our findings show a disrupted cohesin barrel and a longer spindle (∼2.4 microns). The reduction in spring stiffness would lead to the increase in spindle length necessary to achieve a force balance with spindle microtubules. In the two-chromosome strain kinetochores are declustered. Additionally, coordination between the clusters moving toward the poles (anaphase A) and spindle elongation (anaphase B) is abrogated resulting in a mid-anaphase pause. The lack of anaphase A suggests that release and expansion of hitherto confined DNA loops contributes to synchronous chromosome segregation in anaphase.
    DOI:  https://doi.org/10.1091/mbc.E25-02-0050
  3. iScience. 2025 May 16. 28(5): 112292
    Preparation for mitosis requires gradual CDK1 activation.
    Karen Akopyan, Zhiyu Hao, Arne Lindqvist.
      G2 phase is considered as a time in which cells prepare for the large structural changes in the following mitosis. Starting at completion of DNA replication, CDK1 and PLK1 kinase activities gradually increase throughout G2 phase until reaching levels that initiate mitosis. Here, we use a combination of experiments and a data-driven mathematical model to study the connection between DNA replication and mitosis. We find that gradual activation of mitotic kinases ensures CDK1-dependent transcription of factors required for mitosis. In addition, we find that gradual activation of CDK1 coordinates CDK1 and PLK1 activation. Conversely, shortening G2 phase by WEE1 inhibition leads to mitotic delays, which can be partially rescued by expression of constitutively active PLK1. Our results show a function for slow mitotic kinase activation through G2 phase and suggest a mechanism for how the timing of mitotic entry is linked to preparation for mitosis.
    Keywords:  Cell biology; Functional aspects of cell biology; Mathematical biosciences
    DOI:  https://doi.org/10.1016/j.isci.2025.112292
  4. Cell Cycle. 2025 Apr 22. 1-20
    Regulation of microtubule growth rates and their impact on chromosomal instability.
    Lia Mara Gomes Paim, Susanne Bechstedt.
      Microtubules are polymers of α/β tubulin dimers that build the mitotic spindle, which segregates duplicated chromosomes during cell division. Microtubule function is governed by dynamic instability, whereby cycles of growth and shrinkage contribute to the forces necessary for chromosome movement. Regulation of microtubule growth velocity requires cell cycle-dependent changes in expression, localization and activity of microtubule-associated proteins (MAPs) as well as tubulin post-translational modifications that modulate microtubule dynamics. It has become clear that optimal microtubule growth velocities are required for proper chromosome segregation and ploidy maintenance. Suboptimal microtubule growth rates can result from altered activity of MAPs and could lead to aneuploidy, possibly by disrupting the establishment of microtubule bundles at kinetochores and altering the mechanical forces required for sister chromatid segregation. Future work using high-resolution, low-phototoxicity microscopy and novel fluorescent markers will be invaluable in obtaining deeper mechanistic insights into how microtubule processes contribute to chromosome segregation.
    Keywords:  Microtubule dynamics; aneuploidy; chromosomal instability; chromosome segregation; microtubule-associated proteins; mitosis
    DOI:  https://doi.org/10.1080/15384101.2025.2485842
  5. Mol Cell Biol. 2025 Apr 24. 1-13
    Protein Phosphatase 1 Regulatory Subunit PNUTS Prevents CENP-A Mislocalization and Chromosomal Instability.
    Vinutha Balachandra, Makenzie Thomas, Roshan L Shrestha, Subhash Chandra Sethi, Raj Chari, Shinjen Lin, Ken Chih-Chien Cheng, Tatiana S Karpova, Natasha J Caplen, Munira A Basrai.
      Chromosomal instability (CIN), a major hallmark of cancer, can be driven by defects in the integrity of centromere or kinetochore structure. Coordinated control of phosphorylation and dephosphorylation activities during cell division is critical to ensure chromosomal stability. Overexpression of the centromeric histone H3 variant CENP-A is observed in many cancers, and its mislocalization to noncentromeric regions promotes CIN. We identified protein phosphatase 1 (PP1) nuclear targeting subunit (PNUTS) as a top candidate in a genome-wide siRNA screen for gene depletions that lead to increased nuclear CENP-A levels. Here, we define a role for PNUTS in preventing CENP-A mislocalization and CIN. Depletion of PNUTS resulted in high nuclear CENP-A levels throughout the cell cycle in a PP1-dependent manner. Consistent with these results, mislocalization of CENP-A and its interacting partner CENP-C were observed on mitotic chromosomes from PNUTS-depleted cells. Defects in kinetochore integrity and CIN phenotypes were also observed in PNUTS-depleted cells. Mechanistically, we show that depletion of the histone H3.3 chaperone DAXX suppresses the mislocalization of CENP-A and micronuclei incidence in PNUTS-depleted cells. In summary, our studies highlight the importance of phospho-regulation mediated by PNUTS in preventing CENP-A mislocalization and CIN.
    Keywords:  CENP-A; PNUTS; PPP1R10; chromosomal instability; protein phosphatase 1
    DOI:  https://doi.org/10.1080/10985549.2025.2487010
  6. Trends Cell Biol. 2025 Apr 23. pii: S0962-8924(25)00043-1. [Epub ahead of print]
    Centrosomes and cancer: balancing tumor-promoting and inhibitory roles.
    Susana A Godinho, Renata Basto.
      The centrosome duplicates only once per cell cycle such that, in preparation for mitosis, cells contain two centrosomes, allowing the formation of a bipolar spindle and segregation of chromosomes to the two daughter cells. Defects in centrosome numbers have long been recognized in human tumors and are postulated to be a driver of malignancy through chromosome instability. However, current work has revealed a multitude of phenotypes associated with amplified centrosomes beyond mitotic defects that may play a role in disease onset and progression, including cancer. This review focuses on the complexity of outcomes connected to centrosome abnormalities and the challenges that result from aberrant loss and gain of centrosome numbers. We discuss the tumor-promoting and inhibitory roles of amplified centrosomes, and propose that their impact on both physiology and disease is intrinsically linked to cellular context.
    Keywords:  centrosome-number alterations; chemotherapy; chromosome instability; immune responses; migration and invasion
    DOI:  https://doi.org/10.1016/j.tcb.2025.02.009
  7. Cytoskeleton (Hoboken). 2025 Apr 21.
    PLK4: Master Regulator of Centriole Duplication and Its Therapeutic Potential.
    Muhammad Hamzah, Franz Meitinger, Midori Ohta.
      Centrosomes catalyze the assembly of a microtubule-based bipolar spindle, essential for the precise chromosome segregation during cell division. At the center of this process lies Polo-Like Kinase 4 (PLK4), the master regulator that controls the duplication of the centriolar core to ensure the correct balance of two centrosomes per dividing cell. Disruptions in centrosome number or function can lead to genetic disorders such as primary microcephaly or drive tumorigenesis via centrosome amplification. In this context, several chemical inhibitors of PLK4 have emerged as promising therapeutic candidates. The inhibition of PLK4 results in the emergence of acentrosomal cells, which undergo prolonged and error-prone mitosis. This aberrant mitotic duration triggers a "mitotic stopwatch" mechanism that activates the tumor suppressor p53, halting cellular proliferation. However, in a multitude of cancers, the efficacy of this mitotic surveillance mechanism is compromised by mutations that incapacitate p53. Recent investigations have unveiled p53-independent vulnerabilities in cancers characterized by chromosomal gain or amplification of 17q23, which encodes for the ubiquitin ligase TRIM37, in response to PLK4 inhibition, particularly in neuroblastoma and breast cancer. This review encapsulates the latest advancements in our understanding of centriole duplication and acentrosomal cell division in the context of TRIM37 amplification, positioning PLK4 as a compelling target for innovative cancer therapeutics.
    Keywords:  cancer; centrioles; centrosome; kinase inhibitor; mitosis; pericentriolar material; therapeutics
    DOI:  https://doi.org/10.1002/cm.22031
  8. Cytoskeleton (Hoboken). 2025 Apr 21.
    Inactivation of the Catalytic Activity of Mps1 Kinase Prevents Its Own Degradation at Centrosomes.
    Shrabani Halder, Arpita Dutta, Rupsa Mondal, Banhi Chowdhury, Benu Brata Das, Shubhra Majumder.
      Mps1 kinase plays important roles in regulating centriole assembly, apart from its essential role in spindle assembly checkpoint. Here we report a novel mode of regulating centrosomal Mps1 level, which is governed by its own catalytic activity that promotes its degradation at centrosomes. A kinase-dead mutant of Mps1 or catalytically inactive Mps1 due to treatment with a specific kinase inhibitor is protected from degradation at centrosomes. This autoregulatory mode of controlling Mps1 activity at centrosomes likely restricts excess centriole production in a dividing cell.
    Keywords:  Mps1 kinase; autophosphorylation; cell cycle; centrioles; centrosomes; kinase inhibitor; proteasomal degradation
    DOI:  https://doi.org/10.1002/cm.22032
  9. Mol Biol Cell. 2025 Apr 23. mbcE24080386
    M-phase-specific generation of supernumerary centrioles in cancer cells.
    Byungho Shin, Myungse Kim, Yejoo Lee, Kunsoo Rhee.
      Many cancer cells maintain supernumerary centrioles, despite the potential risks associated with catastrophic outcomes during mitosis. In this study, we searched for cancer cell lines in which supernumerary centrioles are generated during the M phase and identified a few cell lines among the dozen examined. PLK4 activity is also required for M-phase-specific generation of supernumerary centrioles. We observed that mitotic centrioles prematurely separate in many cancer cells when levels of pericentriolar material (PCM) proteins, such as PCNT and CEP215, are low. Furthermore, the presence of supernumerary centrioles was correlated with reduced mitotic PCM levels. Notably, overexpression of PCNT led to a reduction in supernumerary centrioles in MDA-MB-157 cells. These findings suggest that diminution of mitotic PCM may be a cause of M-phase-specific generation of supernumerary centrioles in selected cancer cells. [Media: see text] [Media: see text] [Media: see text] [Media: see text].
    DOI:  https://doi.org/10.1091/mbc.E24-08-0386
  10. Methods Mol Biol. 2025 ;2926 91-100
    Nuclear Morphology-Based Assessment of Cell Fates Induced by a Microtubule Targeting Agent as a Single Treatment or Combined with an Oncolytic Virus.
    Sucheta De, Marcelo Ehrlich.
      Immunofluorescence microscopy allows for the quantitative assessment of cell fate at single-cell resolution. This is required to analyze heterogeneous cell populations, as the assessment of average values of given parameters does not faithfully describe distinct states of specific subpopulations. As a case in point, we describe a methodology for characterizing the effects of a microtubule targeting agent, 2-methoxestradiol (2ME2), on T24 human bladder cancer cells. We employ an immunofluorescence-based assessment of nuclear morphology, DNA content, and the intracellular distribution pattern of microtubules for the identification/classification of cells undergoing mitosis or mitotic slippage. When combined with imaging-based identification of cells expressing a nonstructural oncolytic virus protein, this approach enables the assessment of the potential for combined treatment with a microtubule targeting agent and an oncolytic virus (e.g., the Epizootic Hemorrhagic Disease Virus-Tel Aviv University, EHDV-TAU).
    Keywords:  Fluorescence microscopy; Microtubule targeting agent; Mitotic slippage; Nuclear morphometry; Oncolytic virus
    DOI:  https://doi.org/10.1007/978-1-0716-4542-0_8
  11. PLoS Genet. 2025 Apr 25. 21(4): e1011678
    Mitochondrial fission surveillance is coupled to Caenorhabditis elegans DNA and chromosome segregation integrity.
    Xiaomeng Yang, Ruichen Wei, Fanfan Meng, Dianchen Liu, Xuan Gong, Gary Ruvkun, Wei Wei.
      Mitochondrial fission and fusion are tightly regulated to specify mitochondrial abundance, localization, and arrangement during cell division as well as in the diverse differentiated cell types and physiological states. However, the regulatory pathways for such mitochondrial dynamics are less explored than the mitochondrial fission and fusion components. Here we report a large-scale screen for genes that regulate mitochondrial fission. Mitochondrial fission defects cause a characteristic uneven fluorescent pattern in embryos carrying mitochondrial stress reporter genes. Using this uneven activation, we performed RNAi screens that identified 3 kinase genes from a ~ 500-kinase library and another 11 genes from 3,300 random genes that function in mitochondrial fission. Many of these identified genes play roles in chromosome segregation. We found that chromosome missegregation and genome instability lead to dysregulation of mitochondrial fission, possibly independent of DRP-1. ATL-1, the C. elegans ATR orthologue, plays a potentially protective role in alleviating the mitochondrial fission defect caused by chromosome missegregation. This establishes a screening paradigm for identifying mitochondrial fission regulators, which reveals the potential role of ATR in surveilling mitochondrial fission to mitigate dysregulation caused by improper chromosome segregation.
    DOI:  https://doi.org/10.1371/journal.pgen.1011678
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