bims-micesi Biomed News
on Mitotic cell signalling
Issue of 2024–11–10
nine papers selected by
Valentina Piano, Uniklinik Köln
  1. Cell type-specific regulation by different cytokinetic pathways in the early embryo.
  2. Unraveling the interaction between a glycolytic regulator protein EhPpdk and an anaphase promoting complex protein EhApc10: yeast two hybrid screening, in vitro binding assays and molecular simulation study.
  3. Motorless transport of microtubules along tubulin, RanGTP, and salt gradients.
  4. VezA/vezatin facilitates proper assembly of the dynactin complex in vivo.
  5. PGV-1 Causes Disarrangement of Spindle Microtubule Organization Resulting in Aberrant Mitosis in HLF and HuH6 Cells Associated with Altered MYCN Status.
  6. Replication stress induces POLQ-mediated structural variant formation throughout common fragile sites after entry into mitosis.
  7. TPX2 serves as a novel target for expanding the utility of PARPi in pancreatic cancer through conferring synthetic lethality.
  8. BubR1 and SIRT2: Insights into Aneuploidy, Aging, and Cancer.
  9. PICH, A protein that maintains genomic stability, can promote tumor growth.
  1. MicroPubl Biol. 2024 ;2024
    Cell type-specific regulation by different cytokinetic pathways in the early embryo.
    Caroline Q Connors, Sophia L Martin, Julien Dumont, Mimi Shirasu-Hiza, Julie C Canman.
      Cytokinesis, the physical division of one cell into two, is typically assumed to use the same molecular process across animal cells. However, regulation of cell division can vary significantly among different cell types, even within the same multicellular organism. Using six fast-acting temperature-sensitive (ts) cytokinesis-defective mutants, we found that each had unique cell type-specific profiles in the early 2-cell through 8-cell C. elegans embryo. Certain cell types were more sensitive than others to actomyosin and spindle signaling disruptions, disrupting two members of the same complex could result in different phenotypes, and protection against actomyosin inhibition did not always protect against spindle signaling inhibition.
    DOI:  https://doi.org/10.17912/micropub.biology.001316
  2. Protein J. 2024 Dec;43(6): 1104-1119
    Unraveling the interaction between a glycolytic regulator protein EhPpdk and an anaphase promoting complex protein EhApc10: yeast two hybrid screening, in vitro binding assays and molecular simulation study.
    Suchetana Pal, Pinaki Biswas, Raktim Ghosh, Somasri Dam.
      The anaphase promoting complex (APC or cyclosome) is a major ubiquitin ligase that coordinates mitotic and G1 progression, acting as a major regulator of chromosome segregation. While the human APC contains fourteen subunits, it is yet to be explored in the pathogen Entamoeba histolytica. Our study reveals the existence of a single functional Apc10 homolog in E. histolytica, which acts as a processivity factor of ubiquitin ligase activity in human. A cDNA library generated from HM1:IMSS strain of E. histolytica was screened for interaction partners of EhApc10 in yeast two hybrid study. The novel interactor, a glycolytic enzyme, pyruvate phosphate dikinase (Ppdk) was found to interact with EhApc10 and further validated by in vitro assay. A comprehensive in silico study has emphasized the structural and functional aspects, encompassing physicochemical traits, predictive 3D structure modelling, validation of EhApc10-EhPpdk interaction through molecular docking and simulation. The interplay between a cell cycle protein and a glycolytic enzyme highlights the connection between cellular metabolism and the cell cycle regulatory mechanism. The study serves as the groundwork for future research on the non-mitotic role of APC beyond cell cycle.
    Keywords:   Entamoeba histolytica ; Anaphase promoting complex; Molecular docking; Pyruvate phosphate dikinase; Yeast two hybrid
    DOI:  https://doi.org/10.1007/s10930-024-10238-5
  3. Nat Commun. 2024 Nov 01. 15(1): 9434
    Motorless transport of microtubules along tubulin, RanGTP, and salt gradients.
    Suin Shim, Bernardo Gouveia, Beatrice Ramm, Venecia A Valdez, Sabine Petry, Howard A Stone.
      Microtubules are dynamic filaments that assemble spindles for eukaryotic cell division. As the concentration profiles of soluble tubulin and regulatory proteins are non-uniform during spindle assembly, we asked if diffusiophoresis - motion of particles under solute gradients - can act as a motorless transport mechanism for microtubules. We identify the migration of stable microtubules along cytoplasmic and higher concentration gradients of soluble tubulin, MgCl2, Mg-ATP, Mg-GTP, and RanGTP at speeds O(100) nm/s, validating the diffusiophoresis hypothesis. Using two buffers (BRB80 and CSF-XB), microtubule behavior under MgCl2 gradients is compared with negatively charged particles and analyzed with a multi-ion diffusiophoresis and diffusioosmosis model. Microtubule diffusiophoresis under gradients of tubulin and RanGTP is also compared with the charged particles and analyzed with a non-electrolyte diffusiophoresis model. Further, we find that tubulin and RanGTP display concentration dependent cross-diffusion that influences microtubule diffusiophoresis. Finally, using Xenopus laevis egg extract, we show that diffusiophoretic transport occurs in an active cytoplasmic environment.
    DOI:  https://doi.org/10.1038/s41467-024-53656-w
  4. Cell Rep. 2024 Nov 01. pii: S2211-1247(24)01294-4. [Epub ahead of print]43(11): 114943
    VezA/vezatin facilitates proper assembly of the dynactin complex in vivo.
    Jun Zhang, Rongde Qiu, Sean Xie, Megan Rasmussen, Xin Xiang.
      Cytoplasmic dynein-mediated intracellular transport needs the multi-component dynactin complex for cargo binding and motor activation. However, the cellular factors involved in dynactin assembly remain unexplored. Here, we found in Aspergillus nidulans that the vezatin homolog VezA is important for dynactin assembly. VezA affects the microtubule plus-end accumulation of dynein before cargo binding and cargo-adapter-mediated dynein activation, two processes that both need dynactin. The dynactin complex contains multiple components, including p150, p50, and an Arp1 (actin-related protein 1) mini-filament associated with a pointed-end sub-complex. VezA physically interacts with the Arp1 mini-filament either directly or indirectly. Loss of VezA significantly decreases the amount of Arp1 pulled down with pointed-end proteins, as well as the protein levels of p50 and p150 in cell extract. Using various dynactin mutants, we further revealed that the dynactin assembly process must be highly coordinated. Together, these results shed light on dynactin assembly in vivo.
    Keywords:  Actin-related protein; AlphaFold2; Aspergillus nidulans; CP: Cell biology; VezA; dynactin; dynein; filamentous fungi; microtubule; vezatin
    DOI:  https://doi.org/10.1016/j.celrep.2024.114943
  5. Adv Pharm Bull. 2024 Oct;14(3): 665-674
    PGV-1 Causes Disarrangement of Spindle Microtubule Organization Resulting in Aberrant Mitosis in HLF and HuH6 Cells Associated with Altered MYCN Status.
    Nadzifa Nugraheni, Ummi Maryam Zulfin, Beni Lestari, Novia Permata Hapsari, Muthi Ikawati, Rohmad Yudi Utomo, Yusuke Suenaga, Yoshitaka Hippo, Edy Meiyanto.
       Purpose: The HLF and HuH-6 cell lines represent hepatocellular carcinoma (HCC) with different characteristics in chromosome content that may give different drug responses. Here, PGV-1 was intended to challenge the growth-suppressing effect on HLF and HuH-6 and trace the molecular target mechanism of action compared to sorafenib.
    Methods: We applied MTT cytotoxic assay, colony forming assay, flow cytometry analysis, immunofluorescence assay and western blot assay.
    Results: PGV-1 exhibited cytotoxic effects on HLF and HuH-6 with IC-50 values of 1 µM and 2 µM, respectively, whereas sorafenib showed less cytotoxicity with IC-50 values of 5 µM and 8 µM respectively. PGV-1 suppressed the cell growth permanently but not for sorafenib. Sorafenib did not change the cell cycle profiles on both cells, but PGV-1 arrested the cells at G2/M with the characteristic of senescent cells and mitotic disarrangement. PGV-1 and sorafenib showed the same effect in downregulating p-EGFR, indicating that both compounds have the same target on EGFR activation or as Tyrosine kinase inhibitors. PGV-1 suppressed the MYCN expression in HuH-6 and HLF cells but stabilized cMYC-T58 indicating that even though the MYCN was downregulated, the cells maintained the active form of cMYC. In this regard, PGV-1 also stabilized the expression of PLK-1 and AurA.
    Conclusion: PGV-1 elicits stronger cytotoxic properties compared to sorafenib. The lower the MYCN expression, the higher the cytotoxic effect of PGV-1. PGV-1 abrogates cell cycle progression of both cells in mitosis through EGFR inhibition and stabilizes PLK-1 and AurA in correlation with the suppression of MYCN expression.
    Keywords:  HCC; MYCN; Microtubule disarrangement; PGV-1; Sorafenib
    DOI:  https://doi.org/10.34172/apb.2024.058
  6. Nat Commun. 2024 Nov 06. 15(1): 9582
    Replication stress induces POLQ-mediated structural variant formation throughout common fragile sites after entry into mitosis.
    Thomas E Wilson, Samreen Ahmed, Amanda Winningham, Thomas W Glover.
      Genomic structural variants (SVs) greatly impact human health, but much is unknown about the mechanisms that generate the largest class of nonrecurrent alterations. Common fragile sites (CFSs) are unstable loci that provide a model for SV formation, especially large deletions, under replication stress. We study SV junction formation as it occurs in human cell lines by applying error-minimized capture sequencing to CFS DNA harvested after low-dose aphidicolin treatment. SV junctions form throughout CFS genes at a 5-fold higher rate after cells pass from G2 into M-phase. Neither SV formation nor CFS expression depend on mitotic DNA synthesis (MiDAS), an error-prone form of replication active at CFSs. Instead, analysis of tens of thousands of de novo SV junctions combined with DNA repair pathway inhibition reveal a primary role for DNA polymerase theta (POLQ)-mediated end-joining (TMEJ). We propose an important role for mitotic TMEJ in nonrecurrent SV formation genome wide.
    DOI:  https://doi.org/10.1038/s41467-024-53917-8
  7. Gut. 2024 Nov 05. pii: gutjnl-2024-332782. [Epub ahead of print]
    TPX2 serves as a novel target for expanding the utility of PARPi in pancreatic cancer through conferring synthetic lethality.
    Mingming Xiao, Rong Tang, Haoqi Pan, Jing Yang, Xuhui Tong, He Xu, Yanmei Guo, Yalan Lei, Di Wu, Yubin Lei, Yamei Han, Zhilong Ma, Wei Wang, Jin Xu, Xianjun Yu, Si Shi.
       BACKGROUND: PARP inhibitors (PARPi) have been licensed for the maintenance therapy of patients with metastatic pancreatic cancer carrying pathogenic germline BRCA1/2 mutations. However, mutations in BRCA1/2 are notably rare in pancreatic cancer.
    OBJECTIVE: There is a significant unmet clinical need to broaden the utility of PARPi.
    DESIGN: RNA sequencing was performed to screen potential targets for PARPi sensitivity. The synthetic lethal effects were verified in patient-derived xenograft (PDX), xenograft and patient-derived organoid models. Mechanisms were explored via LC‒MS/MS, coimmunoprecipitation, laser microirradiation, immunofluorescence, the homologous recombination (HR) or non-homologous end joining (NHEJ) reporter system, in situ proximity ligation assay and live-cell time-lapse imaging analyses.
    RESULTS: Targeting protein for Xenopus kinesin-like protein 2 (TPX2) is an exploitable vulnerability. TPX2 was downregulated in PDX models sensitive to PARPi, and TPX2 inhibition conferred synthetic lethality to PARPi both in vitro and in vivo. Mechanistically, TPX2 functions in a cell cycle-dependent manner. In the S/G2 phase, ATM-mediated TPX2 S634 phosphorylation promotes BRCA1 recruitment to double-strand breaks (DSBs) for HR repair, whereas non-phosphorylated TPX2 interacts with 53BP1 to recruit it for NHEJ. The balance between phosphorylated and non-phosphorylated TPX2 determines the DSB repair pathway choice. During mitosis, TPX2 phosphorylation enhances Aurora A activity, promoting mitotic progression and chromosomal stability. Targeting TPX2 S634 phosphorylation with a cell-penetrating peptide causes genomic instability and mitotic catastrophe and enhances PARPi sensitivity. Additionally, the inhibition of TPX2 or S634 phosphorylation combined with gemcitabine further sensitised pancreatic cancer to PARPi.
    CONCLUSIONS: Our findings revealed the dual-functional significance of TPX2 in controlling DNA DSB repair pathway choice and mitotic progression, suggesting a potential therapeutic strategy involving PARPi for patients with pancreatic cancer.
    Keywords:  CELL BIOLOGY; CELL SIGNALLING; CHEMOTHERAPY; DRUG RESISTANCE; PANCREATIC CANCER
    DOI:  https://doi.org/10.1136/gutjnl-2024-332782
  8. Semin Cancer Biol. 2024 Oct 26. pii: S1044-579X(24)00083-X. [Epub ahead of print]
    BubR1 and SIRT2: Insights into Aneuploidy, Aging, and Cancer.
    Renju Pun, Niti Kumari, Rodaina Hazem Monieb, Sachin Wagh, Brian J North.
      Aging is a significant risk factor for cancer which is due, in part, to heightened genomic instability. Mitotic surveillance proteins such as BubR1 play a pivotal role in ensuring accurate chromosomal segregation and preventing aneuploidy. BubR1 levels have been shown to naturally decline with age and its loss is associated with various age-related pathologies. Sirtuins, a class of NAD+-dependent deacylases, are implicated in cancer and genomic instability. Among them, SIRT2 acts as an upstream regulator of BubR1, offering a critical pathway that can potentially mitigate age-related diseases, including cancer. In this review, we explore BubR1 as a key regulator of cellular processes crucial for aging-related phenotypes. We delve into the intricate mechanisms through which BubR1 influences genomic stability and cellular senescence. Moreover, we highlight the role of NAD+ and SIRT2 in modulating BubR1 expression and function, emphasizing its potential as a therapeutic target. The interaction between BubR1 and SIRT2 not only serves as a fundamental regulatory pathway in cellular homeostasis but also represents a promising avenue for developing targeted therapies against age-related diseases, particularly cancer.
    Keywords:  Aging; Aneuploidy; BubR1; Cancer; SIRT2; Senescence; Sirtuins
    DOI:  https://doi.org/10.1016/j.semcancer.2024.10.005
  9. Gene. 2024 Nov 02. pii: S0378-1119(24)00955-7. [Epub ahead of print]935 149074
    PICH, A protein that maintains genomic stability, can promote tumor growth.
    Zeyuan Li, Wentao Zhang, Zihan Zhang, Guoming Mao, Linping Qi, Yubin Wang, Hanteng Yang, Huili Ye.
      Genomic instability is regardedas a hallmark of cancer cells. It can be presented in many ways, among which chromosome instability has received attention. Ultrafine anaphase bridges are a typeof chromatin bridges, the untimely resolution of which can also lead to chromosome instability. PICH can play a role in maintaining chromosome stability by regulating chromosome morphologyand resolving ultrafine anaphase bridges. Recently, PICH has been found to be overexpressed in various cancers. Overexpression of PICH is related to the proliferation of tumors and poor prognosis. In this article, we consider that PICH can maintain genomic stability by regulating appropriate chromosome structure, ensuring proper chromosome segregation, and facilitating replication fork reversal. We summarize how PICH regulates chromosome stability, how PICH resolves Ultrafine anaphase bridges with other proteins, and how PICH promotes tumor progression.
    Keywords:  Cancer; Chromosome segregation; Genomic stability; PICH; TOP2A; Ultrafine anaphase bridges
    DOI:  https://doi.org/10.1016/j.gene.2024.149074
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