bims-micesi Biomed News
on Mitotic cell signalling
Issue of 2022–02–27
twelve papers selected by
Valentina Piano, Max Planck Institute of Molecular Physiology
  1. Role of ubiquitin-protein ligase UBR5 in the disassembly of mitotic checkpoint complexes.
  2. NAT10 regulates mitotic cell fate by acetylating Eg5 to control bipolar spindle assembly and chromosome segregation.
  3. The spindle checkpoint proteins BUB1 and BUBR1: (SLiM)ming down to the basics.
  4. A Journey through Time on the Discovery of Cell Cycle Regulation.
  5. Cytotoxic mechanism of tioconazole involves cell cycle arrest at mitosis through inhibition of microtubule assembly.
  6. A back-up source of microtubules for the midbody during cytokinesis.
  7. The intricate roles of RCC1 in normal cells and cancer cells.
  8. Division site determination during asymmetric cell division in plants.
  9. Rec8 Cohesin: A Structural Platform for Shaping the Meiotic Chromosomes.
  10. Computer-Aided Assessment of Melanocytic Lesions by Means of a Mitosis Algorithm.
  11. Identifying Mitotic Kinesins as Potential Prognostic Biomarkers in Ovarian Cancer Using Bioinformatic Analyses.
  12. Phosphorylation of small kinetochore-associated protein induced by GSK3β promotes cell migration and invasion in esophageal cancer.
  1. Proc Natl Acad Sci U S A. 2022 Mar 01. pii: e2121478119. [Epub ahead of print]119(9):
    Role of ubiquitin-protein ligase UBR5 in the disassembly of mitotic checkpoint complexes.
    Sharon Kaisari, Shirly Miniowitz-Shemtov, Danielle Sitry-Shevah, Pnina Shomer, Guennadi Kozlov, Kalle Gehring, Avram Hershko.
      The mitotic (or spindle assembly) checkpoint system ensures accurate chromosome segregation in mitosis by preventing the onset of anaphase until correct bipolar attachment of sister chromosomes to the mitotic spindle is attained. It acts by promoting the assembly of a mitotic checkpoint complex (MCC), composed of mitotic checkpoint proteins BubR1, Bub3, Mad2, and Cdc20. MCC binds to and inhibits the action of ubiquitin ligase APC/C (anaphase-promoting complex/cyclosome), which targets for degradation regulators of anaphase initiation. When the checkpoint system is satisfied, MCCs are disassembled, allowing the recovery of APC/C activity and initiation of anaphase. Many of the pathways of the disassembly of the different MCCs have been elucidated, but the mode of their regulation remained unknown. We find that UBR5 (ubiquitin-protein ligase N-recognin 5) is associated with the APC/C*MCC complex immunopurified from extracts of nocodazole-arrested HeLa cells. UBR5 binds to mitotic checkpoint proteins BubR1, Bub3, and Cdc20 and promotes their polyubiquitylation in vitro. The dissociation of a Bub3*BubR1 subcomplex of MCC is stimulated by UBR5-dependent ubiquitylation, as suggested by observations that this process in mitotic extracts requires UBR5 and α-β bond hydrolysis of adenosine triphosphate. Furthermore, a system reconstituted from purified recombinant components carries out UBR5- and ubiquitylation-dependent dissociation of Bub3*BubR1. Immunodepletion of UBR5 from mitotic extracts slows down the release of MCC components from APC/C and prolongs the lag period in the recovery of APC/C activity in the exit from mitotic checkpoint arrest. We suggest that UBR5 may be involved in the regulation of the inactivation of the mitotic checkpoint.
    Keywords:  cell cycle; mitosis; ubiquitin
    DOI:  https://doi.org/10.1073/pnas.2121478119
  2. Cell Death Differ. 2022 Feb 24.
    NAT10 regulates mitotic cell fate by acetylating Eg5 to control bipolar spindle assembly and chromosome segregation.
    Jiaojiao Zheng, Yuqin Tan, Xiaofeng Liu, Chunfeng Zhang, Kunqi Su, Yang Jiang, Jianyuan Luo, Li Li, Xiaojuan Du.
      Cell fate of mitotic cell is controlled by spindle assembly. Deficient spindle assembly results in mitotic catastrophe leading to cell death to maintain cellular homeostasis. Therefore, inducing mitotic catastrophe provides a strategy for tumor therapy. Nucleolar acetyltransferase NAT10 has been found to regulate various cellular processes to maintain cell homeostasis. Here we report that NAT10 regulates mitotic cell fate by acetylating Eg5. NAT10 depletion results in multinuclear giant cells, which is the hallmark of mitotic catastrophe. Live-cell imaging showed that knockdown of NAT10 dramatically prolongs the mitotic time and induces defective chromosome segregation including chromosome misalignment, bridge and lagging. NAT10 binds and co-localizes with Eg5 in the centrosome during mitosis. Depletion of NAT10 reduces the centrosome loading of Eg5 and impairs the poleward movement of centrosome, leading to monopolar and asymmetrical spindle formation. Furthermore, NAT10 stabilizes Eg5 through its acetyltransferase function. NAT10 acetylates Eg5 at K771 to control Eg5 stabilization. We generated K771-Ac specific antibody and showed that Eg5 K771-Ac specifically localizes in the centrosome during mitosis. Additionally, K771 acetylation is required for the motor function of Eg5. The hyper-acetylation mimic Flag-Eg5 K771Q but not Flag-Eg5 rescued the NAT10 depletion-induced defective spindle formation and mitotic catastrophe, demonstrating that NAT10 controls mitosis through acetylating Eg5 K771. Collectively, we identify Eg5 as an important substrate of NAT10 in the control of mitosis and provide K771 as an essential acetylation site in the stabilization and motor function of Eg5. Our findings reveal that targeting the NAT10-mediated Eg5 K771 acetylation provides a potential strategy for tumor therapy.
    DOI:  https://doi.org/10.1038/s41418-021-00899-5
  3. Trends Biochem Sci. 2022 Feb 17. pii: S0968-0004(22)00007-X. [Epub ahead of print]
    The spindle checkpoint proteins BUB1 and BUBR1: (SLiM)ming down to the basics.
    Sabine Elowe, Victor M Bolanos-Garcia.
      Benzimidazole 1 (BUB1) and budding uninhibited by benzimidazole 1-related 1 (BUBR1) are multidomain paralogs with key roles in chromosome alignment during mitosis and the spindle assembly checkpoint (SAC), an evolutionarily conserved signaling pathway that monitors errors in chromosome segregation during cell division in eukaryotes. Although BUB1 and BUBR1 share a similar domain organization and short linear interaction motifs (SLiMs), they control distinct aspects of chromosome congression and the SAC. Here we discuss the roles of BUB1 and BUBR1 SLiMs in mitosis and complement this with additional insights gleamed from studying their evolution. We show that BUB1 and BUBR1 SLiMs form highly specific interactions that are carefully orchestrated in space and time and contend that they define BUB1 and BUBR1 as organizing hubs that drive SAC signaling and ensure genome stability.
    Keywords:  SAC signaling; genome instability; mitosis regulation; protein organizing hub; short linear interaction motifs (SLiMs)
    DOI:  https://doi.org/10.1016/j.tibs.2022.01.004
  4. Cells. 2022 Feb 17. pii: 704. [Epub ahead of print]11(4):
    A Journey through Time on the Discovery of Cell Cycle Regulation.
    Rustem Uzbekov, Claude Prigent.
      All living organisms on Earth are made up of cells, which are the functional unit of life. Eukaryotic organisms can consist of a single cell (unicellular) or a group of either identical or different cells (multicellular). Biologists have always been fascinated by how a single cell, such as an egg, can give rise to an entire organism, such as the human body, composed of billions of cells, including hundreds of different cell types. This is made possible by cell division, whereby a single cell divides to form two cells. During a symmetric cell division, a mother cell produces two daughter cells, while an asymmetric cell division results in a mother and a daughter cell that have different fates (different morphologies, cellular compositions, replicative potentials, and/or capacities to differentiate). In biology, the cell cycle refers to the sequence of events that a cell must go through in order to divide. These events, which always occur in the same order, define the different stages of the cell cycle: G1, S, G2, and M. What is fascinating about the cell cycle is its universality, and the main reason for this is that the genetic information of the cell is encoded by exactly the same molecular entity with exactly the same structure: the DNA double helix. Since both daughter cells always inherit their genetic information from their parent cell, the underlying fundamentals of the cell cycle-DNA replication and chromosome segregation-are shared by all organisms. This review goes back in time to provide a historical summary of the main discoveries that led to the current understanding of how cells divide and how cell division is regulated to remain highly reproducible.
    Keywords:  cdk; cell cycle; checkpoint; cyclin; history; regulation
    DOI:  https://doi.org/10.3390/cells11040704
  5. Cytotechnology. 2022 Feb;74(1): 141-162
    Cytotoxic mechanism of tioconazole involves cell cycle arrest at mitosis through inhibition of microtubule assembly.
    Jomon Sebastian, Krishnan Rathinasamy.
      Tioconazole is one of the drugs used to treat topical mycotic infections. It exhibited severe toxicity during systemic administration; however, the molecular mechanism behind the cytotoxic effect was not well established. We employed HeLa cells as a model to investigate the molecular mechanism of its toxicity and discovered that tioconazole inhibited HeLa cell growth through mitotic block (37%). At the half-maximal inhibitory concentration (≈ 15 μM) tioconazole apparently depolymerized microtubules and caused defects in chromosomal congression at the metaphase plate. Tioconazole induced apoptosis and significantly hindered the migration of HeLa cells. Tioconazole bound to goat brain tubulin (K d, 28.3 ± 0.5 μM) and inhibited the assembly of microtubules in the in vitro assays. We report for the first time that tioconazole binds near to the colchicine site, based on the evidence from in vitro tubulin competition experiment and computational analysis. The conformation of tubulin dimer was found to be "curved" upon binding with tioconazole in the MD simulation. Tioconazole in combination with vinblastine synergistically inhibited the growth of HeLa cells and augmented the percentage of mitotic block by synergistically inhibiting the assembly of microtubules. Our study indicates that the systemic adverse effects of tioconazole are partly due to its effects on microtubules and cell cycle arrest. Since tioconazole is well tolerated at the topical level, it could be developed as a topical anticancer agent in combination with other systemic anticancer drugs.
    Graphical abstract:
    Supplementary Information: The online version contains supplementary material available at 10.1007/s10616-021-00516-w.
    Keywords:  Apoptosis; Azole; Cancer; Mitosis; Tubulin
    DOI:  https://doi.org/10.1007/s10616-021-00516-w
  6. J Cell Biol. 2022 03 07. pii: e202201028. [Epub ahead of print]221(3):
    A back-up source of microtubules for the midbody during cytokinesis.
    Gilles R X Hickson.
      During cytokinesis, microtubules become compacted into a dense midbody prior to abscission. Using genetic perturbations and imaging of C. elegans zygotes, Hirsch et al. (2022. J. Cell Biol.https://doi.org/10.1083/jcb.202011085) uncover an unexpected source of microtubules that can populate the midbody when central spindle microtubules are missing.
    DOI:  https://doi.org/10.1083/jcb.202201028
  7. Biochem Soc Trans. 2022 Feb 22. pii: BST20210861. [Epub ahead of print]
    The intricate roles of RCC1 in normal cells and cancer cells.
    Li Jing, Hang Fai Kwok.
      RCC1 (regulator of chromosome condensation 1) is a highly conserved chromatin-binding protein and the only known guanine-nucleotide exchange factor of Ran (a nuclear Ras homolog). RCC1 plays an essential role in the regulation of cell cycle-related activities such as nuclear envelope formation, nuclear pore complex and spindle assembly, and nucleocytoplasmic transport. Over the last decade, increasing evidence has emerged highlighting the potential relevance of RCC1 to carcinogenesis, especially cervical, lung, and breast cancer. In this review, we briefly discuss the roles of RCC1 in both normal and tumor cells based on articles published in recent years, followed by a brief overview of future perspectives in the field.
    Keywords:  cell cycle reguation; chromatin; chromosome condensation; tumorigenesis
    DOI:  https://doi.org/10.1042/BST20210861
  8. Plant Cell. 2022 Feb 24. pii: koac069. [Epub ahead of print]
    Division site determination during asymmetric cell division in plants.
    Peishan Yi, Gohta Goshima.
      During development, both animals and plants exploit asymmetric cell division to increase tissue complexity, a process that usually generates cells dissimilar in size, morphology, and fate. Plants lack the key regulators that control asymmetric cell division in animals. Instead, plants have evolved two unique cytoskeletal structures to tackle this problem: the preprophase band and phragmoplast. The assembly of the preprophase band and phragmoplast and their contributions to division plane orientation have been extensively studied. However, how the division plane is positioned off the cell center during asymmetric division is poorly understood. Over the past 20 years, emerging evidence points to a critical role for polarly localized membrane proteins in this process. Although many of these proteins are species- or cell type-specific, and the molecular mechanism underlying division asymmetry is not fully understood, common features such as morphological changes in cells, cytoskeletal dynamics, and nuclear positioning have been observed. In this review, we provide updates on polarity establishment and nuclear positioning during asymmetric cell division in plants. Together with previous findings about symmetrically dividing cells and the emerging roles of developmental cues, we aim to offer evolutionary insight into a common framework for asymmetric division-site determination and highlight directions for future work.
    DOI:  https://doi.org/10.1093/plcell/koac069
  9. Genes (Basel). 2022 Jan 22. pii: 200. [Epub ahead of print]13(2):
    Rec8 Cohesin: A Structural Platform for Shaping the Meiotic Chromosomes.
    Takeshi Sakuno, Yasushi Hiraoka.
      Meiosis is critically different from mitosis in that during meiosis, pairing and segregation of homologous chromosomes occur. During meiosis, the morphology of sister chromatids changes drastically, forming a prominent axial structure in the synaptonemal complex. The meiosis-specific cohesin complex plays a central role in the regulation of the processes required for recombination. In particular, the Rec8 subunit of the meiotic cohesin complex, which is conserved in a wide range of eukaryotes, has been analyzed for its function in modulating chromosomal architecture during the pairing and recombination of homologous chromosomes in meiosis. Here, we review the current understanding of Rec8 cohesin as a structural platform for meiotic chromosomes.
    Keywords:  Pds5; Rec8; Wpl1; axis-loop structure; chromosome; cohesin; homolog pairing; meiosis; recombination; synaptonemal complex
    DOI:  https://doi.org/10.3390/genes13020200
  10. Diagnostics (Basel). 2022 Feb 08. pii: 436. [Epub ahead of print]12(2):
    Computer-Aided Assessment of Melanocytic Lesions by Means of a Mitosis Algorithm.
    Bart Sturm, David Creytens, Jan Smits, Ariadne H A G Ooms, Erik Eijken, Eline Kurpershoek, Heidi V N Küsters-Vandevelde, Carla Wauters, Willeke A M Blokx, Jeroen A W M van der Laak.
      An increasing number of pathology laboratories are now fully digitised, using whole slide imaging (WSI) for routine diagnostics. WSI paves the road to use artificial intelligence (AI) that will play an increasing role in computer-aided diagnosis (CAD). In melanocytic skin lesions, the presence of a dermal mitosis may be an important clue for an intermediate or a malignant lesion and may indicate worse prognosis. In this study a mitosis algorithm primarily developed for breast carcinoma is applied to melanocytic skin lesions. This study aimed to assess whether the algorithm could be used in diagnosing melanocytic lesions, and to study the added value in diagnosing melanocytic lesions in a practical setting. WSI's of a set of hematoxylin and eosin (H&E) stained slides of 99 melanocytic lesions (35 nevi, 4 intermediate melanocytic lesions, and 60 malignant melanomas, including 10 nevoid melanomas), for which a consensus diagnosis was reached by three academic pathologists, were subjected to a mitosis algorithm based on AI. Two academic and six general pathologists specialized in dermatopathology examined the WSI cases two times, first without mitosis annotations and after a washout period of at least 2 months with mitosis annotations based on the algorithm. The algorithm indicated true mitosis in lesional cells, i.e., melanocytes, and non-lesional cells, i.e., mainly keratinocytes and inflammatory cells. A high number of false positive mitosis was indicated as well, comprising melanin pigment, sebaceous glands nuclei, and spindle cell nuclei such as stromal cells and neuroid differentiated melanocytes. All but one pathologist reported more often a dermal mitosis with the mitosis algorithm, which on a regular basis, was incorrectly attributed to mitoses from mainly inflammatory cells. The overall concordance of the pathologists with the consensus diagnosis for all cases excluding nevoid melanoma (n = 89) appeared to be comparable with and without the use of AI (89% vs. 90%). However, the concordance increased by using AI in nevoid melanoma cases (n = 10) (75% vs. 68%). This study showed that in general cases, pathologists perform similarly with the aid of a mitosis algorithm developed primarily for breast cancer. In nevoid melanoma cases, pathologists perform better with the algorithm. From this study, it can be learned that pathologists need to be aware of potential pitfalls using CAD on H&E slides, e.g., misinterpreting dermal mitoses in non-melanotic cells.
    Keywords:  WSI; computer-aided diagnosis; melanoma; mitosis algorithm; nevoid melanoma
    DOI:  https://doi.org/10.3390/diagnostics12020436
  11. Diagnostics (Basel). 2022 Feb 12. pii: 470. [Epub ahead of print]12(2):
    Identifying Mitotic Kinesins as Potential Prognostic Biomarkers in Ovarian Cancer Using Bioinformatic Analyses.
    Hailun Liu, Chen Chen, Tanja Fehm, Zhongping Cheng, Hans Neubauer.
      Ovarian cancer (OC) is characterized by late-stage presentation, chemoresistance, and poor survival. Evaluating the prognosis of OC patients via effective biomarkers is essential to manage OC progression and to improve survival; however, it has been barely established. Here, we intend to identify differentially expressed genes (DEGs) as potential prognostic biomarkers of OC via bioinformatic analyses. Initially, a total of thirteen DEGs were extracted from different public databases as candidates. The expression of KIF20A, one of the DEGs, was correlated with a worse outcome of OC patients. The functional correlation of the DEGs with mitosis and the prognostic value of KIF20A imply a high correlation between mitotic kinesins (KIFs) and OC development. Finally, we found that KIF20A, together with the other nine mitotic KIFs (4A, 11, 14, 15, 18A, 18B, 23, C1, and2C) were upregulated and activated in OC tissues. Among the ten, seven overexpressed mitotic KIFs (11, 14, 18B, 20A, 23, and C1) were correlated with unfavorable clinical prognosis. Moreover, KIF20A and KIF23 overexpression was associated with worse prognosis in OC patients treated with platinum/taxol chemotherapy, while OCs overexpressing mitotic KIFs (11, 15, 18B, and C1) were resistant to MAPK pathway inhibitors. In conclusion, worse outcomes of OC patients were correlated with overexpression of several mitotic KIFs, which may serve both as prognostic biomarkers and therapeutic targets for OC.
    Keywords:  bioinformatic analyses; mitotic kinesins; ovarian cancer; prognostic biomarkers; therapeutic targets
    DOI:  https://doi.org/10.3390/diagnostics12020470
  12. Cell Cycle. 2022 Feb 24. 1-12
    Phosphorylation of small kinetochore-associated protein induced by GSK3β promotes cell migration and invasion in esophageal cancer.
    Bo Qin, Zhu Zhu, Fanxiang Yin, Dan Yan, Jiajia Wan, Meng Dong, Zhengyang Wang.
      Glycogen synthesis kinase-3β (GSK-3β) is a kinase shown to regulate esophageal cancer (EC) progression. However, the significance of GSK-3β in phosphorylation of small kinetochore-associated protein (SKAP) has not been fully characterized. GSK-3β/SKAP expression was analyzed in EC tissues by RT-qPCR. The association between GSK-3β expression and the overall survival was analyzed using the Kaplan-Meier method. Transwell and wound healing assays were performed to assess the effects of GSK-3β/SKAP knockdown on EC cell migration and invasion. By in vitro kinase assay, the SKAP T294 site was identified as a phosphorylated target of GSK-3β. Moreover, we established two cell lines expressing either T294D (phosphor-mimic) or T294A (phosphor-deficiency) SKAP to analyze the effect of SKAP phosphorylation on EC cell invasion, migration, and epithelial-mesenchymal transition (EMT) process. GSK-3β was overexpressed and positively correlated with SKAP levels in EC tissues. Increased GSK-3β expression was associated with EC poor prognosis. Both of GSK-3β knockdown and silencing SKAP decreased EC cell migration and invasion. GSK-3β phosphorylated SKAP protein at Thr294 site. Additionally, a T294D mutant SKAP enhanced cell migration, invasion, and EMT process. Conversely, a T294A mutant SKAP inhibited EC cell malignancy. Meanwhile, cell invasion and migration abilities were inhibited after silencing GSK-3β in EC109-WT, EC109-T294A and EC109-T294D cells. Phosphorylation of SKAP induced by GSK-3β promoted EC cell migration and invasion.
    Keywords:  Esophageal cancer; GSK-3β; SKAP; phosphorylation
    DOI:  https://doi.org/10.1080/15384101.2022.2038847
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