bims-micesi Biomed News
on Mitotic cell signalling
Issue of 2022‒02‒13
fifteen papers selected by
Valentina Piano
Max Planck Institute of Molecular Physiology
  1. Novel CRK-Cyclin Complex Controls Spindle Assembly Checkpoint in Toxoplasma Endodyogeny.
  2. Naegleria's mitotic spindles are built from unique tubulins and highlight core spindle features.
  3. Particulate matter (PM10) destabilizes mitotic spindle through downregulation of SETD2 in A549 lung cancer cells.
  4. Exclusive modifications of NuMA in malignant epithelial cells: a potential therapeutic mechanism.
  5. Spatiotemporal expression of regulatory kinases directs the transition from mitosis to cellular morphogenesis in Drosophila.
  6. Mechanism of spindle pole organization and instability in human oocytes.
  7. Cdc6 is sequentially regulated by PP2A-Cdc55, Cdc14, and Sic1 for origin licensing in S. cerevisiae.
  8. TORC1 inactivation promotes APC/C-dependent mitotic slippage in yeast and human cells.
  9. Plk1 regulates mutant IDH1 enzyme activity and mutant IDH2 ubiquitination in mitosis.
  10. IMB5476, a novel microtubule inhibitor, induces mitotic catastrophe and overcomes multidrug resistance in tumors.
  11. Kinesin motor KIFC1 is required for tubulin acetylation and actin-dependent spindle migration in mouse oocyte meiosis.
  12. Stabilization of AURKA by the E3 ubiquitin ligase CBLC in lung adenocarcinoma.
  13. Glutamine synthetase licenses APC/C-mediated mitotic progression to drive cell growth.
  14. CENPF/CDK1 signaling pathway enhances the progression of adrenocortical carcinoma by regulating the G2/M-phase cell cycle.
  15. MRBLE-pep Measurements Reveal Accurate Binding Affinities for B56, a PP2A Regulatory Subunit.
  1. mBio. 2022 Feb 08. e0356121
    Novel CRK-Cyclin Complex Controls Spindle Assembly Checkpoint in Toxoplasma Endodyogeny.
    Lauren M Hawkins, Anatoli V Naumov, Mrinalini Batra, Changqi Wang, Dale Chaput, Elena S Suvorova.
      Opportunistic parasites of the Apicomplexa phylum use a variety of division modes built on two types of cell cycles that incorporate two distinctive mechanisms of mitosis: uncoupled from and coupled to parasite budding. Parasites have evolved novel factors to regulate such unique replication mechanisms that are poorly understood. Here, we have combined genetics, quantitative fluorescence microscopy, and global proteomics approaches to examine endodyogeny in Toxoplasma gondii dividing by mitosis coupled to cytokinesis. In the current study, we focus on the steps controlled by the recently described atypical Cdk-related kinase T. gondii Crk6 (TgCrk6). While inspecting protein complexes, we found that this previously orphaned TgCrk6 kinase interacts with a parasite-specific atypical cyclin, TgCyc1. We built conditional expression models and examined primary cell cycle defects caused by the lack of TgCrk6 or TgCyc1. Quantitative microscopy assays revealed that tachyzoites deficient in either TgCrk6 or the cyclin partner TgCyc1 exhibit identical mitotic defects, suggesting cooperative action of the complex components. Further examination of the mitotic structures indicated that the TgCrk6/TgCyc1 complex regulates metaphase. This novel finding confirms a functional spindle assembly checkpoint (SAC) in T. gondii. Measuring global changes in protein expression and phosphorylation, we found evidence that canonical activities of the Toxoplasma SAC are intertwined with parasite-specific tasks. Analysis of phosphorylation motifs suggests that Toxoplasma metaphase is regulated by CDK, mitogen-activated kinase (MAPK), and Aurora kinases, while the TgCrk6/TgCyc1 complex specifically controls the centromere-associated network. IMPORTANCE The rate of Toxoplasma tachyzoite division directly correlates with the severity of the disease, toxoplasmosis, which affects humans and animals. Thus, a better understanding of the tachyzoite cell cycle would offer much-needed efficient tools to control the acute stage of infection. Although tachyzoites divide by binary division, the cell cycle architecture and regulation differ significantly from the conventional binary fission of their host cells. Unlike the unidirectional conventional cell cycle, the Toxoplasma budding cycle is braided and is regulated by multiple essential Cdk-related kinases (Crks) that emerged in the place of missing conventional cell cycle regulators. How these novel Crks control apicomplexan cell cycles is largely unknown. Here, we have discovered a novel parasite-specific complex, TgCrk6/TgCyc1, that orchestrates a major mitotic event, the spindle assembly checkpoint. We demonstrated that tachyzoites incorporated parasite-specific tasks in the canonical checkpoint functions.
    Keywords:  Apicomplexa; Toxoplasma gondii; apicomplexan parasites; cell cycle; cyclin; cyclin-dependent kinase; endodyogeny; mitosis; protein phosphorylation; spindle assembly checkpoint
    DOI:  https://doi.org/10.1128/mbio.03561-21
  2. Curr Biol. 2022 Feb 03. pii: S0960-9822(22)00045-8. [Epub ahead of print]
    Naegleria's mitotic spindles are built from unique tubulins and highlight core spindle features.
    Katrina B Velle, Andrew S Kennard, Monika Trupinić, Arian Ivec, Andrew J M Swafford, Emily Nolton, Luke M Rice, Iva M Tolić, Lillian K Fritz-Laylin, Patricia Wadsworth.
      Naegleria gruberi is a unicellular eukaryote whose evolutionary distance from animals and fungi has made it useful for developing hypotheses about the last common eukaryotic ancestor. Naegleria amoebae lack a cytoplasmic microtubule cytoskeleton and assemble microtubules only during mitosis and thus represent a unique system for studying the evolution and functional specificity of mitotic tubulins and the spindles they assemble. Previous studies show that Naegleria amoebae express a divergent α-tubulin during mitosis, and we now show that Naegleria amoebae express a second mitotic α- and two mitotic β-tubulins. The mitotic tubulins are evolutionarily divergent relative to typical α- and β-tubulins and contain residues that suggest distinct microtubule properties. These distinct residues are conserved in mitotic tubulin homologs of the "brain-eating amoeba" Naegleria fowleri, making them potential drug targets. Using quantitative light microscopy, we find that Naegleria's mitotic spindle is a distinctive barrel-like structure built from a ring of microtubule bundles. Similar to those of other species, Naegleria's spindle is twisted, and its length increases during mitosis, suggesting that these aspects of mitosis are ancestral features. Because bundle numbers change during metaphase, we hypothesize that the initial bundles represent kinetochore fibers and secondary bundles function as bridging fibers.
    Keywords:  Naegleria; cytoskeleton; evolutionary cell biology; microtubules; mitosis; protist; spindle; tubulin
    DOI:  https://doi.org/10.1016/j.cub.2022.01.034
  3. Chemosphere. 2022 Feb 05. pii: S0045-6535(22)00393-9. [Epub ahead of print]295 133900
    Particulate matter (PM10) destabilizes mitotic spindle through downregulation of SETD2 in A549 lung cancer cells.
    Miguel Santibáñez-Andrade, Yesennia Sánchez-Pérez, Yolanda I Chirino, Rocío Morales-Bárcenas, Raúl Quintana-Belmares, Claudia M García-Cuellar.
      Air pollution represents an environmental problem, impacting negatively in human health. Particulate matter of 10 μm or less in diameter (PM10) is related to pulmonary diseases, including lung cancer. Mitotic spindle is made up by chromosome-microtubule (MT) interactions, where SETD2 plays an important role in MT stability. SETD2 binds and activates α-TUBULIN sub-unit and promotes MT polymerization. Alongside this mechanism, the spindle assembly checkpoint (SAC) senses the adequate mitotic progression through proteins such as BUBR1, AURORA B and SURVIVIN. Alterations in MT dynamics as well as in SAC cause aneuploidy and chromosomal instability, a common phenotype in cancer cells. In this study, we evaluated the effect of PM10 in the expression and protein levels of SETD2, as well as the effect in the expression and protein levels of SAC and mitotic components involved in chromosomal segregation/mitosis, using the A549 lung cancer cell line. A549 cell cultures were exposed to PM10 (10 μg/cm2) for 24 h to evaluate the expression and protein levels of SETD2 (SETD2), TUBA1A (α-TUBULIN), CCNB1 (CYCLIN B1), BUB1B (BUBR1), AURKB (AURORA B) and BIRC5 (SURVIVIN). We observed that PM10 decreases the expression and protein levels of SETD2, α-TUBULIN and BUBR1 and increases the levels of AURORA B and SURVIVIN in A549 cells, compared with non-treated cells. PM10 also caused a decrease in mitotic index and in the percentage of cells in G2/M when compared with control group. Co-localization of SETD2/α -TUB was lower in PM10-treated cells in comparison with non-treated cells. Finally, micronuclei (MN) frequency was higher in PM10-treated cells in contrast with non-treated cells, being whole chromosomes more common in PM10-treated MN than in non-treated MN. Our results suggest that PM10 causes missegregation and aneuploidy through downregulation of SETD2 and SAC components, inducing aneuploidy and predisposing to the generation of chromosomal instability in transformed cells.
    Keywords:  A549; Aneuploidy; Chromosomal instability; Mitotic spindle; PM(10); SETD2
    DOI:  https://doi.org/10.1016/j.chemosphere.2022.133900
  4. Drug Discov Today. 2022 Feb 07. pii: S1359-6446(22)00042-3. [Epub ahead of print]
    Exclusive modifications of NuMA in malignant epithelial cells: a potential therapeutic mechanism.
    Malka Cohen-Armon.
      NuMA (nuclear mitotic apparatus) protein is indispensable in the mitosis of human proliferating cells, both malignant and benign. The progression of mitosis requires stable spindles, which depend on the bipolar clustering of NuMA within the spindles. The phenanthridine PJ34 kills malignant epithelial cells during mitosis and targets NuMA. PJ34 exclusively blocks the post-translational modification of NuMA in a variety of malignant epithelial cells, but not in benign cells. This blockage of the post-translational modification of NuMA affects its protein-binding capacity and causes construction faults in the mitotic spindle poles of PJ34-treated cancer cells, leading to mitotic catastrophe cell death. PJ34 is a potent PARP1 inhibitor, so its cytotoxicity in human malignant cells is exclusively independent of PARP, challenging the currently accepted notion that inhibition of PARP1 halts cancer by preventing DNA repair. Certain molecules that act as PARP1 inhibitors target other proteins and vital mechanisms in human cancer cells.
    Keywords:  NuMA; PARP1 inhibitors; PJ34; human malignant epithelial cells; mitotic catastrophe cell death; mitotic spindle
    DOI:  https://doi.org/10.1016/j.drudis.2022.02.002
  5. Nat Commun. 2022 Feb 09. 13(1): 772
    Spatiotemporal expression of regulatory kinases directs the transition from mitosis to cellular morphogenesis in Drosophila.
    Shuo Yang, Jennifer McAdow, Yingqiu Du, Jennifer Trigg, Paul H Taghert, Aaron N Johnson.
      Embryogenesis depends on a tightly regulated balance between mitosis, differentiation, and morphogenesis. Understanding how the embryo uses a relatively small number of proteins to transition between growth and morphogenesis is a central question of developmental biology, but the mechanisms controlling mitosis and differentiation are considered to be fundamentally distinct. Here we show the mitotic kinase Polo, which regulates all steps of mitosis in Drosophila, also directs cellular morphogenesis after cell cycle exit. In mitotic cells, the Aurora kinases activate Polo to control a cytoskeletal regulatory module that directs cytokinesis. We show that in the post-mitotic mesoderm, the control of Polo activity transitions from the Aurora kinases to the uncharacterized kinase Back Seat Driver (Bsd), where Bsd and Polo cooperate to regulate muscle morphogenesis. Polo and its effectors therefore direct mitosis and cellular morphogenesis, but the transition from growth to morphogenesis is determined by the spatiotemporal expression of upstream activating kinases.
    DOI:  https://doi.org/10.1038/s41467-022-28322-8
  6. Science. 2022 Feb 11. 375(6581): eabj3944
    Mechanism of spindle pole organization and instability in human oocytes.
    Chun So, Katerina Menelaou, Julia Uraji, Katarina Harasimov, Anna M Steyer, K Bianka Seres, Jonas Bucevičius, Gražvydas Lukinavičius, Wiebke Möbius, Claus Sibold, Andreas Tandler-Schneider, Heike Eckel, Rüdiger Moltrecht, Martyn Blayney, Kay Elder, Melina Schuh.
      Human oocytes are prone to assembling meiotic spindles with unstable poles, which can favor aneuploidy in human eggs. The underlying causes of spindle instability are unknown. We found that NUMA (nuclear mitotic apparatus protein)-mediated clustering of microtubule minus ends focused the spindle poles in human, bovine, and porcine oocytes and in mouse oocytes depleted of acentriolar microtubule-organizing centers (aMTOCs). However, unlike human oocytes, bovine, porcine, and aMTOC-free mouse oocytes have stable spindles. We identified the molecular motor KIFC1 (kinesin superfamily protein C1) as a spindle-stabilizing protein that is deficient in human oocytes. Depletion of KIFC1 recapitulated spindle instability in bovine and aMTOC-free mouse oocytes, and the introduction of exogenous KIFC1 rescued spindle instability in human oocytes. Thus, the deficiency of KIFC1 contributes to spindle instability in human oocytes.
    DOI:  https://doi.org/10.1126/science.abj3944
  7. Elife. 2022 02 10. pii: e74437. [Epub ahead of print]11
    Cdc6 is sequentially regulated by PP2A-Cdc55, Cdc14, and Sic1 for origin licensing in S. cerevisiae.
    Jasmin Philip, Mihkel Örd, Andriele Silva, Shaneen Singh, John Fx Diffley, Dirk Remus, Mart Loog, Amy E Ikui.
      Cdc6, a subunit of the pre-replicative complex (pre-RC), contains multiple regulatory cyclin-dependent kinase (Cdk1) consensus sites, SP or TP motifs. In Saccharomyces cerevisiae, Cdk1 phosphorylates Cdc6-T7 to recruit Cks1, the Cdk1 phospho-adaptor in S phase, for subsequent multisite phosphorylation and protein degradation. Cdc6 accumulates in mitosis and is tightly bound by Clb2 through N-terminal phosphorylation in order to prevent premature origin licensing and degradation. It has been extensively studied how Cdc6 phosphorylation is regulated by the cyclin-Cdk1 complex. However, a detailed mechanism on how Cdc6 phosphorylation is reversed by phosphatases has not been elucidated. Here, we show that PP2ACdc55 dephosphorylates Cdc6 N-terminal sites to release Clb2. Cdc14 dephosphorylates the C-terminal phospho-degron, leading to Cdc6 stabilization in mitosis. In addition, Cdk1 inhibitor Sic1 releases Clb2·Cdk1·Cks1 from Cdc6 to load Mcm2-7 on the chromatin upon mitotic exit. Thus, pre-RC assembly and origin licensing are promoted by phosphatases through the attenuation of distinct Cdk1-dependent Cdc6 inhibitory mechanisms.
    Keywords:  Cdc14; Cdc55; Cdc6; DNA replication; PP2A; S. cerevisiae; cell biology; phosphatase
    DOI:  https://doi.org/10.7554/eLife.74437
  8. iScience. 2022 Feb 18. 25(2): 103675
    TORC1 inactivation promotes APC/C-dependent mitotic slippage in yeast and human cells.
    Chihiro Yamada, Aya Morooka, Seira Miyazaki, Masayoshi Nagai, Satoru Mase, Kenji Iemura, Most Naoshia Tasnin, Tsuneyuki Takuma, Shotaro Nakamura, Shamsul Morshed, Naoki Koike, Md Golam Mostofa, Muhammad Arifur Rahman, Tasnuva Sharmin, Haruko Katsuta, Kotaro Ohara, Kozo Tanaka, Takashi Ushimaru.
      Unsatisfied kinetochore-microtubule attachment activates the spindle assembly checkpoint to inhibit the metaphase-anaphase transition. However, some cells eventually override mitotic arrest by mitotic slippage. Here, we show that inactivation of TORC1 kinase elicits mitotic slippage in budding yeast and human cells. Yeast mitotic slippage was accompanied with aberrant aspects, such as degradation of the nucleolar protein Net1, release of phosphatase Cdc14, and anaphase-promoting complex/cyclosome (APC/C)-Cdh1-dependent degradation of securin and cyclin B in metaphase. This mitotic slippage caused chromosome instability. In human cells, mammalian TORC1 (mTORC1) inactivation also invoked mitotic slippage, indicating that TORC1 inactivation-induced mitotic slippage is conserved from yeast to mammalian cells. However, the invoked mitotic slippage in human cells was not dependent on APC/C-Cdh1. This study revealed an unexpected involvement of TORC1 in mitosis and provides information on undesirable side effects of the use of TORC1 inhibitors as immunosuppressants and anti-tumor drugs.
    Keywords:  Biological sciences; Cell biology; Molecular biology
    DOI:  https://doi.org/10.1016/j.isci.2021.103675
  9. Cell Signal. 2022 Feb 07. pii: S0898-6568(22)00039-0. [Epub ahead of print] 110279
    Plk1 regulates mutant IDH1 enzyme activity and mutant IDH2 ubiquitination in mitosis.
    M Sai Kiran Reddy, Debanjan Bhattacharjee, Nishant Jain.
      Mutations in the metabolic enzymes, IDH1 and IDH2 are frequently found in glioma, chondrosarcoma, and acute myeloid leukemia. In our previous study, we showed that mutant IDH1 and IDH2 proteins levels are high in mitosis, and mutant IDH1 enzyme activity increases in mitosis. In another study, we observed that mutant IDH2 is ubiquitinated in mitosis in an APC/C-dependent manner. To orchestrate mitosis, kinases phosphorylate key proteins and regulate their functions. But it is unknown, whether mitotic kinases regulate mutant IDH1 and IDH2. As IDH1 and IDH2 have 66% sequence identity, thus we hypothesized that a common mitotic kinase(s) may regulate mutant IDH1 and IDH2 in mitosis. To test our hypothesis, we examined mutant IDH1 and IDH2 binding to mitotic kinases and determined their role in regulating mutant IDH1 and IDH2 in mitosis. Here, we observed that Cdk1/Cyclin B1 phosphorylated mutant IDH1 and IDH2 binds Plk1. Conserved Plk1 phosphobinding sites in IDH1 and IDH2 are important for Plk1 binding. We found that Plk1 regulates mutant IDH1 enzyme activity and blocking Plk1 decreases D-2HG, whereas, overexpressing Plk1 increases D-2HG levels. Furthermore, blocking Plk1 decreases mutant IDH2 ubiquitination, whereas, overexpressing Plk1 increases mutant IDH2 ubiquitination in mitosis. We conclude that Plk1 regulates mutant IDH1 enzyme activity and mutant IDH2 ubiquitination in mitosis. Based on our results, we suggest that Plk1 can be a therapeutic target in mutant IDH-linked tumours.
    Keywords:  Cdk1/cyclin B1; D-2HG; Mutant IDH1; Mutant IDH2; Plk1; Ubiquitination
    DOI:  https://doi.org/10.1016/j.cellsig.2022.110279
  10. Eur J Pharmacol. 2022 Feb 07. pii: S0014-2999(22)00063-2. [Epub ahead of print] 174802
    IMB5476, a novel microtubule inhibitor, induces mitotic catastrophe and overcomes multidrug resistance in tumors.
    Yan-Bo Zheng, Yan-Qun Dong, Shu-Yi Si, Yong-Su Zhen, Jian-Hua Gong.
      IMB5046 is a nitrobenzoate microtubule inhibitor we reported previously. During screening of its structural analogues, we identified a novel compound IMB5476 with increased aqueous solubility. Here, its antitumor activity and the underlying mechanism were investigated. IMB5476 disrupted microtubule networks in cells and arrested cell cycle at G2/M phase. It inhibited purified tubulin polymerization in vitro. Competition assay indicated that it bound to tubulin at the colchicine pocket. Further experiments proved that it induced cell death by mitotic catastrophe and apoptosis. Notably, it was a poor substrate of P-glycoprotein and exhibited potent cytotoxicity against drug-resistant tumor cells. In addition, IMB5476 could inhibit angiogenesis in vitro. IMB5476 also inhibited the growth of drug-resistant KBV200 xenografts in mice. Conclusively, our data reveal a novel nitrobenzoate microtubule inhibitor with improved aqueous solubility and can overcome multidrug resistance.
    Keywords:  Angiogenesis; Microtubule inhibitor; Mitotic catastrophe; Multidrug resistance; Nitrobenzoate
    DOI:  https://doi.org/10.1016/j.ejphar.2022.174802
  11. Development. 2022 Feb 10. pii: dev.200231. [Epub ahead of print]
    Kinesin motor KIFC1 is required for tubulin acetylation and actin-dependent spindle migration in mouse oocyte meiosis.
    Meng-Meng Shan, Yuan-Jing Zou, Zhen-Nan Pan, Hao-Lin Zhang, Yi Xu, Jia-Qian Ju, Shao-Chen Sun.
      Mammalian oocyte maturation is a unique asymmetric division, which is mainly due to actin-based spindle migration to the cortex. In present study, we reported that a kinesin motor KIFC1, which was associated with microtubules for the maintenance of spindle poles in mitosis, was also involved into actin dynamics in oocyte meiosis. KIFC1 co-localized with microtubules during mouse oocyte maturation. Depletion of KIFC1 caused the failure of polar body extrusion, and we found that meiotic spindle formation and chromosome alignment were disrupted. This might be due to the effects of KIFC1 on HDAC6 and NAT10-based tubulin acetylation, which further affected microtubule stability. Mass spectroscopy analysis revealed that KIFC1 also associated with several actin nucleation factors and we found that KIFC1 was essential for the distribution of actin filaments, which further affected spindle migration. Depletion of KIFC1 leaded to aberrant expression of Formin2 and ARP2/3 complex, and ER distribution was also disturbed. Exogenous KIFC1 mRNA supplement could rescue these defects. Taken together, besides its roles on tubulin acetylation, our study also reported a novel role of kinesin KIFC1 on the regulation of actin dynamics for spindle migration in mouse oocytes.
    Keywords:  Actin; Kinesin; Meiosis; Oocyte; Tubulin acetylation
    DOI:  https://doi.org/10.1242/dev.200231
  12. Oncogene. 2022 Feb 12.
    Stabilization of AURKA by the E3 ubiquitin ligase CBLC in lung adenocarcinoma.
    Shiao-Ya Hong, Yi-Chun Lu, Shih-Hsin Hsiao, Yu-Rung Kao, Meng-Hsuan Lee, Yi-Ping Lin, Cheng-Yi Wang, Cheng-Wen Wu.
      CBL family proteins (CBL, CBLB and CBLC in mammals) are E3 ubiquitin ligases of protein tyrosine kinases. CBL mediates the lysosomal degradation of activated EGFR through K63-linked ubiquitination, while CBLC has an oncogenic function by positively regulating EGFR activation through K6 and K11-linked ubiquitination in EGFR mutant lung adenocarcinoma (LAD). Here, we used immunoprecipitation and mass spectrometry to study the CBLC interactome, and found that CBLC is also involved in cell cycle regulation by stabilizing Aurora kinase A (AURKA). CBLC interacted with the kinase domain of AURKA and positively regulated the stability of AURKA by conjugating monoubiquitination and K11/K63-linked polyubiquitination, which are protective from degrading K11/K48 polyubiquitination. CBLC depletion markedly decreased the half-life of AURKA in cycloheximide-treated LAD cells. When LAD cells were synchronized with double thymidine block at the G1/S boundary and then released into mitotic arrest, CBLC depletion delayed the accumulation and activation of AURKA and prevented cancer cells from entering mitosis. CBLC deficiency significantly delayed cell cycle progression, reduced the mitotic population, and increased apoptosis of LAD cells. Targeting CBLC inhibited tumor growth of LAD cells and enhanced their sensitivity to paclitaxel in xenograft models. Immunohistochemical staining of the tissue microarray also revealed a positive correlation between the expression of CBLC and AURKA in normal and LAD tissues, further supporting the positive regulation of AURKA expression by CBLC. In summary, these findings indicate that the oncogenic E3 ligase CBLC plays a role in mitotic entry by stabilizing AURKA via ubiquitination in LAD. This work demonstrates that targeting CBLC combined with paclitaxel might be a potential option for the treatment of LAD patients who have no available targeted therapies.
    DOI:  https://doi.org/10.1038/s41388-022-02180-6
  13. Nat Metab. 2022 Feb 10.
    Glutamine synthetase licenses APC/C-mediated mitotic progression to drive cell growth.
    Jiang-Sha Zhao, Shuo Shi, Hai-Yan Qu, Zuzana Keckesova, Zi-Jian Cao, Li-Xian Yang, Xiaofu Yu, Limin Feng, Zhong Shi, Joanna Krakowiak, Ruo-Ying Mao, Yi-Tong Shen, Yu-Meng Fan, Tian-Min Fu, Cunqi Ye, Daqian Xu, Xiaofei Gao, Jia You, Wenbo Li, Tingbo Liang, Zhimin Lu, Yu-Xiong Feng.
      Tumors can reprogram the functions of metabolic enzymes to fuel malignant growth; however, beyond their conventional functions, key metabolic enzymes have not been found to directly govern cell mitosis. Here, we report that glutamine synthetase (GS) promotes cell proliferation by licensing mitotic progression independently of its metabolic function. GS depletion, but not impairment of its enzymatic activity, results in mitotic arrest and multinucleation across multiple lung and liver cancer cell lines, patient-derived organoids and xenografted tumors. Mechanistically, GS directly interacts with the nuclear pore protein NUP88 to prevent its binding to CDC20. Such interaction licenses activation of the CDC20-mediated anaphase-promoting complex or cyclosome to ensure proper metaphase-to-anaphase transition. In addition, GS is overexpressed in human non-small cell lung cancer and its depletion reduces tumor growth in mice and increases the efficacy of microtubule-targeted chemotherapy. Our findings highlight a moonlighting function of GS in governing mitosis and illustrate how an essential metabolic enzyme promotes cell proliferation and tumor development, beyond its main metabolic function.
    DOI:  https://doi.org/10.1038/s42255-021-00524-2
  14. J Transl Med. 2022 Feb 05. 20(1): 78
    CENPF/CDK1 signaling pathway enhances the progression of adrenocortical carcinoma by regulating the G2/M-phase cell cycle.
    Yu-Gang Huang, Dan Li, Li Wang, Xiao-Min Su, Xian-Bin Tang.
      BACKGROUND: Adrenocortical carcinoma (ACC) is an aggressive and rare malignant tumor and is prone to local invasion and metastasis. And, overexpressed Centromere Protein F (CENPF) is closely related to the oncogenesis of various neoplasms, including ACC. However, the prognosis and exact biological function of CENPF in ACC remains largely unclear.METHODS: In the present essay, the expression patterns and prognostic value of CENPF in ACC were investigated in clinical specimens and public cancer databases, including GEO and TCGA. The potential signaling mechanism of CENPF in ACC was studied based on gene-set enrichment analysis (GSEA). Furthermore, a small RNA interference experiment was conducted to probe the underlying biological function of CENPF in the human ACC cell line, SW13 cells. Lastly, two available therapeutic strategies, including immunotherapy and chemotherapy, have been further explored.
    RESULTS: The expression of CENPF in human ACC samples, GEO, and TCGA databases depicted that CENPF was overtly hyper-expressed in ACC patients and positively correlated with tumor stage. The aberrant expression of CENPF was significantly correlated with unfavorable overall survival (OS) in ACC patients. Then, the GSEA analysis declared that CENPF was mainly involved in the G2/M-phase mediated cell cycle and p53 signaling pathway. Further, the in vitro experiment demonstrated that the interaction between CENPF and CDK1 augmented the G2/M-phase transition of mitosis, cell proliferation and might induce p53 mediated anti-tumor effect in human ACC cell line, SW13 cells. Lastly, immune infiltration analysis highlighted that ACC patients with high CENPF expression harbored significantly different immune cell populations, and high TMB/MSI score. The gene-drug interaction network stated that CENPF inhibitors, such as Cisplatin, Sunitinib, and Etoposide, might serve as potential drugs for the therapy of ACC.
    CONCLUSION: The result points out that CENPF is significantly overexpressed in ACC patients. The overexpressed CENPF predicts a poor prognosis of ACC and might augment the progress of ACC. Thus, CENPF and related genes might serve as a novel prognostic biomarker or latent therapeutic target for ACC patients.
    Keywords:  ACC; Adrenocortical carcinoma; CDK1; CENPF; Cell cycle; p53
    DOI:  https://doi.org/10.1186/s12967-022-03277-y
  15. ACS Meas Sci Au. 2021 Oct 20. 1(2): 56-64
    MRBLE-pep Measurements Reveal Accurate Binding Affinities for B56, a PP2A Regulatory Subunit.
    Jamin B Hein, Martha S Cyert, Polly M Fordyce.
      Signal transduction pathways rely on dynamic interactions between protein globular domains and short linear motifs (SLiMs). The weak affinities of these interactions are essential to allow fast rewiring of signaling pathways and downstream responses but also pose technical challenges for interaction detection and measurement. We recently developed a technique (MRBLE-pep) that leverages spectrally encoded hydrogel beads to measure binding affinities between a single protein of interest and 48 different peptide sequences in a single small volume. In prior work, we applied it to map the binding specificity landscape between calcineurin and the PxIxIT SLiM (Nguyen, H. Q. et al. Elife 2019, 8). Here, using peptide sequences known to bind the PP2A regulatory subunit B56α, we systematically compare affinities measured by MRBLE-pep or isothermal calorimetry (ITC) and confirm that MRBLE-pep accurately quantifies relative affinity over a wide dynamic range while using a fraction of the material required for traditional methods such as ITC.
    Keywords:  B56; MRBLE-pep; PP2A; binding affinities; signal transduction
    DOI:  https://doi.org/10.1021/acsmeasuresciau.1c00008
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