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Devillers R, Dos Santos A, Destombes Q, Laplante M, Elowe S. Recent insights into the causes and consequences of chromosome mis-segregation. Oncogene 2024:10.1038/s41388-024-03163-5. [PMID: 39278989 DOI: 10.1038/s41388-024-03163-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2024] [Revised: 09/04/2024] [Accepted: 09/06/2024] [Indexed: 09/18/2024]
Abstract
Mitotic cells face the challenging task of ensuring accurate and equal segregation of their duplicated, condensed chromosomes between the nascent daughter cells. Errors in the process result in chromosome missegregation, a significant consequence of which is the emergence of aneuploidy-characterized by an imbalance in chromosome number-and the associated phenomenon of chromosome instability (CIN). Aneuploidy and CIN are common features of cancer, which leverages them to promote genome heterogeneity and plasticity, thereby facilitating rapid tumor evolution. Recent research has provided insights into how mitotic errors shape cancer genomes by inducing both numerical and structural chromosomal changes that drive tumor initiation and progression. In this review, we survey recent findings regarding the mitotic causes and consequences of aneuploidy. We discuss new findings into the types of chromosome segregation errors that lead to aneuploidy and novel pathways that protect genome integrity during mitosis. Finally, we describe new developments in our understanding of the immediate consequences of chromosome mis-segregation on the genome stability of daughter cells.
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Affiliation(s)
- Romain Devillers
- Centre de Recherche sur le Cancer, CHU de Québec-Université Laval, Québec City, QC, Canada
- Centre de recherche du Centre Hospitalier Universitaire (CHU) de Québec-Université Laval, Axe de reproduction, santé de la mère et de l'enfant, Québec, QC, Canada
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec (CRIUCPQ), Faculté de Médecine, Université Laval, Québec, QC, Canada
- Regroupement Québécois de Recherche sur la Fonction, L'ingénierie et les Applications des Protéines, Québec, Canada
| | - Alexsandro Dos Santos
- Centre de Recherche sur le Cancer, CHU de Québec-Université Laval, Québec City, QC, Canada
- Centre de recherche du Centre Hospitalier Universitaire (CHU) de Québec-Université Laval, Axe de reproduction, santé de la mère et de l'enfant, Québec, QC, Canada
- Regroupement Québécois de Recherche sur la Fonction, L'ingénierie et les Applications des Protéines, Québec, Canada
| | - Quentin Destombes
- Centre de Recherche sur le Cancer, CHU de Québec-Université Laval, Québec City, QC, Canada
- Centre de recherche du Centre Hospitalier Universitaire (CHU) de Québec-Université Laval, Axe de reproduction, santé de la mère et de l'enfant, Québec, QC, Canada
- Regroupement Québécois de Recherche sur la Fonction, L'ingénierie et les Applications des Protéines, Québec, Canada
| | - Mathieu Laplante
- Centre de Recherche sur le Cancer, CHU de Québec-Université Laval, Québec City, QC, Canada
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec (CRIUCPQ), Faculté de Médecine, Université Laval, Québec, QC, Canada
| | - Sabine Elowe
- Centre de Recherche sur le Cancer, CHU de Québec-Université Laval, Québec City, QC, Canada.
- Centre de recherche du Centre Hospitalier Universitaire (CHU) de Québec-Université Laval, Axe de reproduction, santé de la mère et de l'enfant, Québec, QC, Canada.
- Regroupement Québécois de Recherche sur la Fonction, L'ingénierie et les Applications des Protéines, Québec, Canada.
- Département de Pédiatrie, Faculté de Médecine, Université Laval, Québec City, QC, Canada.
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Le Cunff Y, Chesneau L, Pastezeur S, Pinson X, Soler N, Fairbrass D, Mercat B, Rodriguez-Garcia R, Alayan Z, Abdouni A, de Neidhardt G, Costes V, Anjubault M, Bouvrais H, Héligon C, Pécréaux J. Unveiling inter-embryo variability in spindle length over time: Towards quantitative phenotype analysis. PLoS Comput Biol 2024; 20:e1012330. [PMID: 39236069 PMCID: PMC11376571 DOI: 10.1371/journal.pcbi.1012330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Accepted: 07/15/2024] [Indexed: 09/07/2024] Open
Abstract
How can inter-individual variability be quantified? Measuring many features per experiment raises the question of choosing them to recapitulate high-dimensional data. Tackling this challenge on spindle elongation phenotypes, we showed that only three typical elongation patterns describe spindle elongation in C. elegans one-cell embryo. These archetypes, automatically extracted from the experimental data using principal component analysis (PCA), accounted for more than 95% of inter-individual variability of more than 1600 experiments across more than 100 different conditions. The two first archetypes were related to spindle average length and anaphasic elongation rate. The third archetype, accounting for 6% of the variability, was novel and corresponded to a transient spindle shortening in late metaphase, reminiscent of kinetochore function-defect phenotypes. Importantly, these three archetypes were robust to the choice of the dataset and were found even considering only non-treated conditions. Thus, the inter-individual differences between genetically perturbed embryos have the same underlying nature as natural inter-individual differences between wild-type embryos, independently of the temperatures. We thus propose that beyond the apparent complexity of the spindle, only three independent mechanisms account for spindle elongation, weighted differently in the various conditions. Interestingly, the spindle-length archetypes covered both metaphase and anaphase, suggesting that spindle elongation in late metaphase is sufficient to predict the late anaphase length. We validated this idea using a machine-learning approach. Finally, given amounts of these three archetypes could represent a quantitative phenotype. To take advantage of this, we set out to predict interacting genes from a seed based on the PCA coefficients. We exemplified this firstly on the role of tpxl-1 whose homolog tpx2 is involved in spindle microtubule branching, secondly the mechanism regulating metaphase length, and thirdly the central spindle players which set the length at anaphase. We found novel interactors not in public databases but supported by recent experimental publications.
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Affiliation(s)
- Yann Le Cunff
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Laurent Chesneau
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Sylvain Pastezeur
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Xavier Pinson
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Nina Soler
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Danielle Fairbrass
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Benjamin Mercat
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Ruddi Rodriguez-Garcia
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Zahraa Alayan
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Ahmed Abdouni
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Gary de Neidhardt
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Valentin Costes
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Mélodie Anjubault
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Hélène Bouvrais
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Christophe Héligon
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Jacques Pécréaux
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
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3
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Silva MP, Ferreira LT, Brás NF, Torres L, Brandão A, Pinheiro M, Cardoso M, Resende A, Vieira J, Palmeira C, Martins G, Silva M, Pinto C, Peixoto A, Silva J, Henrique R, Maia S, Maiato H, Teixeira MR, Paulo P. BUB1B monoallelic germline variants contribute to prostate cancer predisposition by triggering chromosomal instability. J Biomed Sci 2024; 31:74. [PMID: 39014450 PMCID: PMC11251299 DOI: 10.1186/s12929-024-01056-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 06/21/2024] [Indexed: 07/18/2024] Open
Abstract
BACKGROUND Prostate cancer (PrCa) is the most frequently diagnosed cancer in men. Variants in known moderate- to high-penetrance genes explain less than 5% of the cases arising at early-onset (< 56 years) and/or with familial aggregation of the disease. Considering that BubR1 is an essential component of the mitotic spindle assembly checkpoint, we hypothesized that monoallelic BUB1B variants could be sufficient to fuel chromosomal instability (CIN), potentially triggering (prostate) carcinogenesis. METHODS To unveil BUB1B as a new PrCa predisposing gene, we performed targeted next-generation sequencing in germline DNA from 462 early-onset/familial PrCa patients and 1,416 cancer patients fulfilling criteria for genetic testing for other hereditary cancer syndromes. To explore the pan-cancer role of BUB1B, we used in silico BubR1 molecular modeling, in vitro gene-editing, and ex vivo patients' tumors and peripheral blood lymphocytes. RESULTS Rare BUB1B variants were found in ~ 1.9% of the early-onset/familial PrCa cases and in ~ 0.6% of other cancer patients fulfilling criteria for hereditary disease. We further show that BUB1B variants lead to decreased BubR1 expression and/or stability, which promotes increased premature chromatid separation and, consequently, triggers CIN, driving resistance to Taxol-based therapies. CONCLUSIONS Our study shows that different BUB1B variants may uncover a trigger for CIN-driven carcinogenesis, supporting the role of BUB1B as a (pan)-cancer predisposing gene with potential impact on genetic counseling and treatment decision-making.
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Affiliation(s)
- Maria P Silva
- Cancer Genetics Group, IPO Porto Research Center (CI-IPOP) / RISE@CI-IPOP (Health Research Network), Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
| | - Luísa T Ferreira
- Cancer Genetics Group, IPO Porto Research Center (CI-IPOP) / RISE@CI-IPOP (Health Research Network), Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
| | - Natércia F Brás
- LAQV, REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Porto, Portugal
| | - Lurdes Torres
- Cancer Genetics Group, IPO Porto Research Center (CI-IPOP) / RISE@CI-IPOP (Health Research Network), Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
- Department of Laboratory Genetics, Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
| | - Andreia Brandão
- Cancer Genetics Group, IPO Porto Research Center (CI-IPOP) / RISE@CI-IPOP (Health Research Network), Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
| | - Manuela Pinheiro
- Cancer Genetics Group, IPO Porto Research Center (CI-IPOP) / RISE@CI-IPOP (Health Research Network), Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
| | - Marta Cardoso
- Cancer Genetics Group, IPO Porto Research Center (CI-IPOP) / RISE@CI-IPOP (Health Research Network), Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
| | - Adriana Resende
- Cancer Genetics Group, IPO Porto Research Center (CI-IPOP) / RISE@CI-IPOP (Health Research Network), Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
- Department of Laboratory Genetics, Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
| | - Joana Vieira
- Cancer Genetics Group, IPO Porto Research Center (CI-IPOP) / RISE@CI-IPOP (Health Research Network), Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
- Department of Laboratory Genetics, Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
| | - Carlos Palmeira
- Department of Immunology, Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
| | - Gabriela Martins
- Department of Immunology, Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
| | - Miguel Silva
- Cancer Genetics Group, IPO Porto Research Center (CI-IPOP) / RISE@CI-IPOP (Health Research Network), Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
- Department of Laboratory Genetics, Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
| | - Carla Pinto
- Cancer Genetics Group, IPO Porto Research Center (CI-IPOP) / RISE@CI-IPOP (Health Research Network), Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
- Department of Laboratory Genetics, Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
| | - Ana Peixoto
- Cancer Genetics Group, IPO Porto Research Center (CI-IPOP) / RISE@CI-IPOP (Health Research Network), Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
- Department of Laboratory Genetics, Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
| | - João Silva
- Cancer Genetics Group, IPO Porto Research Center (CI-IPOP) / RISE@CI-IPOP (Health Research Network), Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
- Department of Laboratory Genetics, Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
| | - Rui Henrique
- Department of Pathology, Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
| | - Sofia Maia
- Cancer Genetics Group, IPO Porto Research Center (CI-IPOP) / RISE@CI-IPOP (Health Research Network), Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
| | - Helder Maiato
- Chromosome Instability & Dynamics Group, Instituto de Investigação e Inovação em Saúde, University of Porto / Porto Comprehensive Cancer Center, Porto, i3S, Portugal
- Cell Division Group, Experimental Biology Unit, Department of Biomedicine, Faculty of Medicine, University of Porto, Porto, Portugal
- Instituto de Biologia Molecular e Celular, University of Porto, Porto, Portugal
| | - Manuel R Teixeira
- Cancer Genetics Group, IPO Porto Research Center (CI-IPOP) / RISE@CI-IPOP (Health Research Network), Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
- Department of Laboratory Genetics, Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal
- School of Medicine and Biomedical Sciences (ICBAS), University of Porto, Porto, Portugal
| | - Paula Paulo
- Cancer Genetics Group, IPO Porto Research Center (CI-IPOP) / RISE@CI-IPOP (Health Research Network), Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center, Porto, Portugal.
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Iglesias-Romero AB, Soto T, Flor-Parra I, Salas-Pino S, Ruiz-Romero G, Gould KL, Cansado J, Daga RR. MAPK-dependent control of mitotic progression in S. pombe. BMC Biol 2024; 22:71. [PMID: 38523261 PMCID: PMC10962199 DOI: 10.1186/s12915-024-01865-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Accepted: 03/08/2024] [Indexed: 03/26/2024] Open
Abstract
BACKGROUND Mitogen-activated protein kinases (MAPKs) preserve cell homeostasis by transducing physicochemical fluctuations of the environment into multiple adaptive responses. These responses involve transcriptional rewiring and the regulation of cell cycle transitions, among others. However, how stress conditions impinge mitotic progression is largely unknown. The mitotic checkpoint is a surveillance mechanism that inhibits mitotic exit in situations of defective chromosome capture, thus preventing the generation of aneuploidies. In this study, we investigate the role of MAPK Pmk1 in the regulation of mitotic exit upon stress. RESULTS We show that Schizosaccharomyces pombe cells lacking Pmk1, the MAP kinase effector of the cell integrity pathway (CIP), are hypersensitive to microtubule damage and defective in maintaining a metaphase arrest. Epistasis analysis suggests that Pmk1 is involved in maintaining spindle assembly checkpoint (SAC) signaling, and its deletion is additive to the lack of core SAC components such as Mad2 and Mad3. Strikingly, pmk1Δ cells show up to twofold increased levels of the anaphase-promoting complex (APC/C) activator Cdc20Slp1 during unperturbed growth. We demonstrate that Pmk1 physically interacts with Cdc20Slp1 N-terminus through a canonical MAPK docking site. Most important, the Cdc20Slp1 pool is rapidly degraded in stressed cells undergoing mitosis through a mechanism that requires MAPK activity, Mad3, and the proteasome, thus resulting in a delayed mitotic exit. CONCLUSIONS Our data reveal a novel function of MAPK in preventing mitotic exit and activation of cytokinesis in response to stress. The regulation of Cdc20Slp1 turnover by MAPK Pmk1 provides a key mechanism by which the timing of mitotic exit can be adjusted relative to environmental conditions.
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Affiliation(s)
| | - Terersa Soto
- Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, Murcia, 30071, Spain
| | - Ignacio Flor-Parra
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide, Seville, 41013, Spain
| | - Silvia Salas-Pino
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide, Seville, 41013, Spain
| | - Gabriel Ruiz-Romero
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide, Seville, 41013, Spain
| | - Kathleen L Gould
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, 37240, USA
| | - José Cansado
- Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, Murcia, 30071, Spain.
| | - Rafael R Daga
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide, Seville, 41013, Spain.
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5
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van Otterdijk S, Motealleh M, Wang Z, Visser TD, Savakis P, Tutucci E. Single-Molecule Fluorescent In Situ Hybridization (smFISH) for RNA Detection in the Fungal Pathogen Candida albicans. Methods Mol Biol 2024; 2784:25-44. [PMID: 38502476 DOI: 10.1007/978-1-0716-3766-1_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2024]
Abstract
Candida albicans is the most prevalent human fungal pathogen. Its pathogenicity is linked to the ability of C. albicans to reversibly change morphology and to grow as yeast, pseudohyphae, or hyphal cells in response to environmental stimuli. Understanding the molecular regulation controlling those morphological switches remains a challenge that, if solved, could help eradicate C. albicans infections.While numerous studies investigated gene expression changes occurring during C. albicans morphological switches using bulk approaches (e.g., RNA sequencing), here we describe a single-cell and single-molecule RNA imaging and analysis protocol to measure absolute mRNA counts in morphologically intact cells. To detect endogenous mRNAs in single fixed cells, we optimized a single-molecule fluorescent in situ hybridization (smFISH) protocol for C. albicans, which allows one to quantify the differential expression of mRNAs in yeast, pseudohyphae, or hyphal cells. We quantified the expression of two mRNAs, a cell cycle-controlled mRNA (CLB2) and a transcription factor (EFG1), which show expression changes in the different morphological cell types and nutrient conditions. In this protocol, we described in detail the major steps of this approach: growth and fixation, hybridization, imaging, cell segmentation, and mRNA spot analysis. Raw data is provided with the protocol to favor reproducibility. This approach could benefit the molecular characterization of C. albicans and other filamentous fungi, pathogenic or nonpathogenic.
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Affiliation(s)
- Sander van Otterdijk
- Systems Biology Lab, A-LIFE department, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Maryam Motealleh
- Systems Biology Lab, A-LIFE department, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Zixu Wang
- Systems Biology Lab, A-LIFE department, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Thomas D Visser
- Systems Biology Lab, A-LIFE department, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
- TNW-BT-IMB, Delft University of Technology, Delft, The Netherlands
| | - Philipp Savakis
- Systems Biology Lab, A-LIFE department, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Evelina Tutucci
- Systems Biology Lab, A-LIFE department, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
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6
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Jema S, Chen C, Humphrey L, Karmarkar S, Ferrari F, Joglekar AP. Signaling protein abundance modulates the strength of the spindle assembly checkpoint. Curr Biol 2023; 33:4505-4515.e4. [PMID: 37738972 PMCID: PMC10615864 DOI: 10.1016/j.cub.2023.08.074] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 07/19/2023] [Accepted: 08/24/2023] [Indexed: 09/24/2023]
Abstract
During mitosis, unattached kinetochores in a dividing cell signal to the spindle assembly checkpoint (SAC) to delay anaphase onset and prevent chromosome missegregation.1,2,3,4 The signaling activity of these kinetochores and the likelihood of chromosome missegregation depend on the amount of SAC signaling proteins each kinetochore recruits.5,6,7,8 Therefore, factors that control SAC protein recruitment must be thoroughly understood. Phosphoregulation of kinetochore and SAC signaling proteins due to the concerted action of many kinases and phosphatases is a significant determinant of the SAC protein recruitment to signaling kinetochores.9 Whether the abundance of SAC proteins also influences the recruitment and signaling activity of human kinetochores has not been studied.8,10 Here, we reveal that the low cellular abundance of the SAC signaling protein Bub1 limits its own recruitment and that of BubR1 and restricts the SAC signaling activity of the kinetochore. Conversely, Bub1 overexpression results in higher recruitment of SAC proteins, producing longer delays in anaphase onset. We also find that the number of SAC proteins recruited by a signaling kinetochore is inversely correlated with the total number of signaling kinetochores in the cell. This correlation likely arises from the competition among the signaling kinetochores to recruit from a limited pool of signaling proteins, including Bub1. The inverse correlation may allow the dividing cell to prevent a large number of signaling kinetochores in early prophase from generating an overly large signal while enabling the last unaligned kinetochore in late prometaphase to signal at the maximum strength.
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Affiliation(s)
- Soubhagyalaxmi Jema
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Chu Chen
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Lauren Humphrey
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Shriya Karmarkar
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Frank Ferrari
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Ajit P Joglekar
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA.
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7
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Weidemann DE, Holehouse J, Singh A, Grima R, Hauf S. The minimal intrinsic stochasticity of constitutively expressed eukaryotic genes is sub-Poissonian. SCIENCE ADVANCES 2023; 9:eadh5138. [PMID: 37556551 PMCID: PMC10411910 DOI: 10.1126/sciadv.adh5138] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 07/07/2023] [Indexed: 08/11/2023]
Abstract
Gene expression inherently gives rise to stochastic variation ("noise") in the production of gene products. Minimizing noise is crucial for ensuring reliable cellular functions. However, noise cannot be suppressed below a certain intrinsic limit. For constitutively expressed genes, this limit is typically assumed to be Poissonian noise, wherein the variance in mRNA numbers is equal to their mean. Here, we demonstrate that several cell division genes in fission yeast exhibit mRNA variances significantly below this limit. The reduced variance can be explained by a gene expression model incorporating multiple transcription and mRNA degradation steps. Notably, in this sub-Poissonian regime, distinct from Poissonian or super-Poissonian regimes, cytoplasmic noise is effectively suppressed through a higher mRNA export rate. Our findings redefine the lower limit of eukaryotic gene expression noise and uncover molecular requirements for achieving ultralow noise, which is expected to be important for vital cellular functions.
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Affiliation(s)
- Douglas E. Weidemann
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
- Fralin Life Sciences Institute, Virginia Tech, Blacksburg, VA 24061, USA
| | - James Holehouse
- The Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87510, USA
| | - Abhyudai Singh
- Department of Electrical and Computer Engineering, University of Delaware, Newark, DE 19716, USA
- Department of Biomedical Engineering, University of Delaware, Newark, DE 19716, USA
| | - Ramon Grima
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JR, UK
| | - Silke Hauf
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
- Fralin Life Sciences Institute, Virginia Tech, Blacksburg, VA 24061, USA
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8
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Ren H, Wang K, Liu Z, Zhong X, Liang M, Liao Y. Effect of Low Dietary Folate on Mouse Spermatogenesis and Spindle Assembly Checkpoint Dysfunction May Contribute to Folate Deficiency-Induced Chromosomal Instability in Cultured Mouse Spermatogonia. DNA Cell Biol 2023; 42:515-525. [PMID: 37289823 DOI: 10.1089/dna.2023.0035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023] Open
Abstract
Folate, as the initial substrate in one-carbon metabolism, is involved in the synthesis of important substances such as DNA, RNA, and protein. Folate deficiency (FD) is associated with male subfertility and impaired spermatogenesis, yet the underlying mechanisms are poorly understood. In the present study, we established an animal model of FD to investigate the effect of FD on spermatogenesis. GC-1 spermatogonia were used as a model to investigate the effect of FD on proliferation, viability, and chromosomal instability (CIN). Furthermore, we explored the expression of core genes and proteins of spindle assembly checkpoint (SAC), a signaling cascade ensuring accurate chromosome segregation and preventing CIN during mitosis. Cells were maintained in medium containing 0, 20, 200, or 2000 nM folate for 14 days. CIN was measured by using a cytokinesis-blocked micronucleus cytome assay. We found that sperm counts decreased significantly (p < 0.001) and the rate of sperm with defects in the head increased significantly (p < 0.05) in FD diet mice. We also found, relative to the folate-sufficient conditions (2000 nM), cells cultured with 0, 20, or 200 nM folate exhibited delayed growth and increased apoptosis in an inverse dose-dependent manner. FD (0, 20, or 200 nM) significantly induced CIN (p < 0.001, p < 0.001, and p < 0.05, respectively). Moreover, FD significantly and inverse dose dependently increased the mRNA and protein expression of several key SAC-related genes. The results indicate that FD impairs SAC activity, which contributes to mitotic aberrations and CIN. These findings establish a novel association between FD and SAC dysfunction. Thus, FD-impaired spermatogenesis may be partly due to genomic instability and proliferation inhibition of spermatogonia.
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Affiliation(s)
- Huanhuan Ren
- School of Life Science, Bengbu Medical College, Bengbu, China
- Department of Clinical Laboratory, Fuyang Fifth People's Hospital, Fuyang, China
| | - Kaixian Wang
- School of Life Science, Bengbu Medical College, Bengbu, China
| | - Zirui Liu
- School of Life Science, Bengbu Medical College, Bengbu, China
| | - Xuansheng Zhong
- School of Life Science, Bengbu Medical College, Bengbu, China
| | - Meng Liang
- School of Life Science, Bengbu Medical College, Bengbu, China
| | - Yaping Liao
- School of Life Science, Bengbu Medical College, Bengbu, China
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9
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MacKenzie A, Vicory V, Lacefield S. Meiotic cells escape prolonged spindle checkpoint activity through kinetochore silencing and slippage. PLoS Genet 2023; 19:e1010707. [PMID: 37018287 PMCID: PMC10109492 DOI: 10.1371/journal.pgen.1010707] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 04/17/2023] [Accepted: 03/20/2023] [Indexed: 04/06/2023] Open
Abstract
To prevent chromosome mis-segregation, a surveillance mechanism known as the spindle checkpoint delays the cell cycle if kinetochores are not attached to spindle microtubules, allowing the cell additional time to correct improper attachments. During spindle checkpoint activation, checkpoint proteins bind the unattached kinetochore and send a diffusible signal to inhibit the anaphase promoting complex/cyclosome (APC/C). Previous work has shown that mitotic cells with depolymerized microtubules can escape prolonged spindle checkpoint activation in a process called mitotic slippage. During slippage, spindle checkpoint proteins bind unattached kinetochores, but the cells cannot maintain the checkpoint arrest. We asked if meiotic cells had as robust of a spindle checkpoint response as mitotic cells and whether they also undergo slippage after prolonged spindle checkpoint activity. We performed a direct comparison between mitotic and meiotic budding yeast cells that signal the spindle checkpoint through two different assays. We find that the spindle checkpoint delay is shorter in meiosis I or meiosis II compared to mitosis, overcoming a checkpoint arrest approximately 150 minutes earlier in meiosis than in mitosis. In addition, cells in meiosis I escape spindle checkpoint signaling using two mechanisms, silencing the checkpoint at the kinetochore and through slippage. We propose that meiotic cells undertake developmentally-regulated mechanisms to prevent persistent spindle checkpoint activity to ensure the production of gametes.
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Affiliation(s)
- Anne MacKenzie
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Victoria Vicory
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Soni Lacefield
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
- Department of Biochemistry and Cell Biology, the Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
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10
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McAinsh AD, Kops GJPL. Principles and dynamics of spindle assembly checkpoint signalling. Nat Rev Mol Cell Biol 2023:10.1038/s41580-023-00593-z. [PMID: 36964313 DOI: 10.1038/s41580-023-00593-z] [Citation(s) in RCA: 55] [Impact Index Per Article: 55.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/22/2023] [Indexed: 03/26/2023]
Abstract
The transmission of a complete set of chromosomes to daughter cells during cell division is vital for development and tissue homeostasis. The spindle assembly checkpoint (SAC) ensures correct segregation by informing the cell cycle machinery of potential errors in the interactions of chromosomes with spindle microtubules prior to anaphase. To do so, the SAC monitors microtubule engagement by specialized structures known as kinetochores and integrates local mechanical and chemical cues such that it can signal in a sensitive, responsive and robust manner. In this Review, we discuss how SAC proteins interact to allow production of the mitotic checkpoint complex (MCC) that halts anaphase progression by inhibiting the anaphase-promoting complex/cyclosome (APC/C). We highlight recent advances aimed at understanding the dynamic signalling properties of the SAC and how it interprets various naturally occurring intermediate attachment states. Further, we discuss SAC signalling in the context of the mammalian multisite kinetochore and address the impact of the fibrous corona. We also identify current challenges in understanding how the SAC ensures high-fidelity chromosome segregation.
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Affiliation(s)
- Andrew D McAinsh
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, UK.
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK.
| | - Geert J P L Kops
- Hubrecht Institute - KNAW (Royal Netherlands Academy of Arts and Sciences) and University Medical Centre Utrecht, Utrecht, The Netherlands.
- Oncode Institute, Utrecht, The Netherlands.
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11
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Sarma U, Ripka L, Anyaegbunam UA, Legewie S. Modeling Cellular Signaling Variability Based on Single-Cell Data: The TGFβ-SMAD Signaling Pathway. Methods Mol Biol 2023; 2634:215-251. [PMID: 37074581 DOI: 10.1007/978-1-0716-3008-2_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2023]
Abstract
Nongenetic heterogeneity is key to cellular decisions, as even genetically identical cells respond in very different ways to the same external stimulus, e.g., during cell differentiation or therapeutic treatment of disease. Strong heterogeneity is typically already observed at the level of signaling pathways that are the first sensors of external inputs and transmit information to the nucleus where decisions are made. Since heterogeneity arises from random fluctuations of cellular components, mathematical models are required to fully describe the phenomenon and to understand the dynamics of heterogeneous cell populations. Here, we review the experimental and theoretical literature on cellular signaling heterogeneity, with special focus on the TGFβ/SMAD signaling pathway.
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Affiliation(s)
- Uddipan Sarma
- Institute of Molecular Biology (IMB), Mainz, Germany
| | - Lorenz Ripka
- Institute of Molecular Biology (IMB), Mainz, Germany
- Department of Systems Biology, Institute for Biomedical Genetics, University of Stuttgart, Stuttgart, Germany
| | - Uchenna Alex Anyaegbunam
- Institute of Molecular Biology (IMB), Mainz, Germany
- Department of Systems Biology, Institute for Biomedical Genetics, University of Stuttgart, Stuttgart, Germany
| | - Stefan Legewie
- Institute of Molecular Biology (IMB), Mainz, Germany.
- Department of Systems Biology, Institute for Biomedical Genetics, University of Stuttgart, Stuttgart, Germany.
- Stuttgart Research Center for Systems Biology, University of Stuttgart, Stuttgart, Germany.
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12
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Bai S, Sun L, Wang X, Wang SM, Luo ZQ, Wang Y, Jin QW. Recovery from spindle checkpoint-mediated arrest requires a novel Dnt1-dependent APC/C activation mechanism. PLoS Genet 2022; 18:e1010397. [PMID: 36108046 PMCID: PMC9514617 DOI: 10.1371/journal.pgen.1010397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 09/27/2022] [Accepted: 08/24/2022] [Indexed: 11/19/2022] Open
Abstract
The activated spindle assembly checkpoint (SAC) potently inhibits the anaphase-promoting complex/cyclosome (APC/C) to ensure accurate chromosome segregation at anaphase. Early studies have recognized that the SAC should be silenced within minutes to enable rapid APC/C activation and synchronous segregation of chromosomes once all kinetochores are properly attached, but the underlying silencers are still being elucidated. Here, we report that the timely silencing of SAC in fission yeast requires dnt1+, which causes severe thiabendazole (TBZ) sensitivity and increased rate of lagging chromosomes when deleted. The absence of Dnt1 results in prolonged inhibitory binding of mitotic checkpoint complex (MCC) to APC/C and attenuated protein levels of Slp1Cdc20, consequently slows the degradation of cyclin B and securin, and eventually delays anaphase entry in cells released from SAC activation. Interestingly, Dnt1 physically associates with APC/C upon SAC activation. We propose that this association may fend off excessive and prolonged MCC binding to APC/C and help to maintain Slp1Cdc20 stability. This may allow a subset of APC/C to retain activity, which ensures rapid anaphase onset and mitotic exit once SAC is inactivated. Therefore, our study uncovered a new player in dictating the timing and efficacy of APC/C activation, which is actively required for maintaining cell viability upon recovery from the inhibition of APC/C by spindle checkpoint.
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Affiliation(s)
- Shuang Bai
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Li Sun
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Xi Wang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Shuang-min Wang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Zhou-qing Luo
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China
- * E-mail: (ZL); (YW); (QJ)
| | - Yamei Wang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China
- * E-mail: (ZL); (YW); (QJ)
| | - Quan-wen Jin
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China
- * E-mail: (ZL); (YW); (QJ)
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13
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Banerjee A, Chen C, Humphrey L, Tyson JJ, Joglekar AP. BubR1 recruitment to the kinetochore via Bub1 enhances spindle assembly checkpoint signaling. Mol Biol Cell 2022; 33:br16. [PMID: 35767360 PMCID: PMC9582629 DOI: 10.1091/mbc.e22-03-0085] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 06/15/2022] [Accepted: 06/21/2022] [Indexed: 11/11/2022] Open
Abstract
During mitosis, unattached kinetochores in a dividing cell activate the spindle assembly checkpoint (SAC) and delay anaphase onset by generating the anaphase-inhibitory mitotic checkpoint complex (MCC). These kinetochores generate the MCC by recruiting its constituent proteins, including BubR1. In principle, BubR1 recruitment to signaling kinetochores should increase its local concentration and promote MCC formation. However, in human cells BubR1 is mainly thought to sensitize the SAC to silencing. Whether BubR1 localization to signaling kinetochores by itself enhances SAC signaling remains unknown. Therefore, we used ectopic SAC activation (eSAC) systems to isolate two molecules that recruit BubR1 to the kinetochore, the checkpoint protein Bub1 and the KI and MELT motifs in the kinetochore protein KNL1, and observed their contribution to eSAC signaling. Our quantitative analyses and mathematical modeling show that Bub1-mediated BubR1 recruitment to the human kinetochore promotes SAC signaling and highlight BubR1's dual role of strengthening the SAC directly and silencing it indirectly.
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Affiliation(s)
- Anand Banerjee
- Academy of Integrated Science, Virginia Polytechnic Institute & State University, Blacksburg, VA 24601
| | - Chu Chen
- Cell & Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109
| | - Lauren Humphrey
- Cell & Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109
| | - John J. Tyson
- Department of Biological Sciences, Virginia Polytechnic Institute & State University, Blacksburg, VA 24601
| | - Ajit P. Joglekar
- Cell & Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109
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14
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Esposito E, Weidemann DE, Rogers JM, Morton CM, Baybay EK, Chen J, Hauf S. Mitotic checkpoint gene expression is tuned by codon usage bias. EMBO J 2022; 41:e107896. [PMID: 35811551 PMCID: PMC9340482 DOI: 10.15252/embj.2021107896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 05/30/2022] [Accepted: 06/06/2022] [Indexed: 11/09/2022] Open
Abstract
The mitotic checkpoint (also called spindle assembly checkpoint, SAC) is a signaling pathway that safeguards proper chromosome segregation. Correct functioning of the SAC depends on adequate protein concentrations and appropriate stoichiometries between SAC proteins. Yet very little is known about the regulation of SAC gene expression. Here, we show in the fission yeast Schizosaccharomyces pombe that a combination of short mRNA half-lives and long protein half-lives supports stable SAC protein levels. For the SAC genes mad2+ and mad3+ , their short mRNA half-lives are caused, in part, by a high frequency of nonoptimal codons. In contrast, mad1+ mRNA has a short half-life despite a higher frequency of optimal codons, and despite the lack of known RNA-destabilizing motifs. Hence, different SAC genes employ different strategies of expression. We further show that Mad1 homodimers form co-translationally, which may necessitate a certain codon usage pattern. Taken together, we propose that the codon usage of SAC genes is fine-tuned to ensure proper SAC function. Our work shines light on gene expression features that promote spindle assembly checkpoint function and suggests that synonymous mutations may weaken the checkpoint.
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Affiliation(s)
- Eric Esposito
- Department of Biological SciencesVirginia TechBlacksburgVAUSA
- Fralin Life Sciences InstituteVirginia TechBlacksburgVAUSA
| | - Douglas E Weidemann
- Department of Biological SciencesVirginia TechBlacksburgVAUSA
- Fralin Life Sciences InstituteVirginia TechBlacksburgVAUSA
| | - Jessie M Rogers
- Department of Biological SciencesVirginia TechBlacksburgVAUSA
- Fralin Life Sciences InstituteVirginia TechBlacksburgVAUSA
| | - Claire M Morton
- Department of Biological SciencesVirginia TechBlacksburgVAUSA
- Fralin Life Sciences InstituteVirginia TechBlacksburgVAUSA
| | - Erod Keaton Baybay
- Department of Biological SciencesVirginia TechBlacksburgVAUSA
- Fralin Life Sciences InstituteVirginia TechBlacksburgVAUSA
| | - Jing Chen
- Department of Biological SciencesVirginia TechBlacksburgVAUSA
- Fralin Life Sciences InstituteVirginia TechBlacksburgVAUSA
| | - Silke Hauf
- Department of Biological SciencesVirginia TechBlacksburgVAUSA
- Fralin Life Sciences InstituteVirginia TechBlacksburgVAUSA
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15
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Zhang Y, Song C, Wang L, Jiang H, Zhai Y, Wang Y, Fang J, Zhang G. Zombies Never Die: The Double Life Bub1 Lives in Mitosis. Front Cell Dev Biol 2022; 10:870745. [PMID: 35646932 PMCID: PMC9136299 DOI: 10.3389/fcell.2022.870745] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 04/06/2022] [Indexed: 11/17/2022] Open
Abstract
When eukaryotic cells enter mitosis, dispersed chromosomes move to the cell center along microtubules to form a metaphase plate which facilitates the accurate chromosome segregation. Meanwhile, kinetochores not stably attached by microtubules activate the spindle assembly checkpoint and generate a wait signal to delay the initiation of anaphase. These events are highly coordinated. Disruption of the coordination will cause severe problems like chromosome gain or loss. Bub1, a conserved serine/threonine kinase, plays important roles in mitosis. After extensive studies in the last three decades, the role of Bub1 on checkpoint has achieved a comprehensive understanding; its role on chromosome alignment also starts to emerge. In this review, we summarize the latest development of Bub1 on supporting the two mitotic events. The essentiality of Bub1 in higher eukaryotic cells is also discussed. At the end, some undissolved questions are raised for future study.
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Affiliation(s)
- Yuqing Zhang
- The Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Chunlin Song
- The Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Lei Wang
- The Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Hongfei Jiang
- The Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Yujing Zhai
- School of Public Health, Qingdao University, Qingdao, China
| | - Ying Wang
- School of Public Health, Qingdao University, Qingdao, China
| | - Jing Fang
- The Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao, China
- *Correspondence: Jing Fang, ; Gang Zhang,
| | - Gang Zhang
- The Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao, China
- *Correspondence: Jing Fang, ; Gang Zhang,
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16
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Vijayakumari D, Müller J, Hauf S. Cdc48 influence on separase levels is independent of mitosis and suggests translational sensitivity of separase. Cell Rep 2022; 38:110554. [PMID: 35320724 PMCID: PMC8995007 DOI: 10.1016/j.celrep.2022.110554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 01/21/2022] [Accepted: 03/02/2022] [Indexed: 11/23/2022] Open
Abstract
Cdc48 (p97/VCP) is a AAA-ATPase that can extract ubiquitinated proteins from their binding partners and can cooperate with the proteasome for their degradation. A fission yeast cdc48 mutant (cdc48-353) shows low levels of the cohesin protease, separase, and pronounced chromosome segregation defects in mitosis. Separase initiates chromosome segregation when its binding partner securin is ubiquitinated and degraded. The low separase levels in the cdc48-353 mutant have been attributed to a failure to extract ubiquitinated securin from separase, resulting in co-degradation of separase along with securin. If true, Cdc48 would be important in mitosis. In contrast, we show here that low separase levels in the cdc48-353 mutant are independent of mitosis. Moreover, we find no evidence of enhanced separase degradation in the mutant. Instead, we suggest that the cdc48-353 mutant uncovers specific requirements for separase translation. Our results highlight a need to better understand how this key mitotic enzyme is synthesized.
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Affiliation(s)
- Drisya Vijayakumari
- Department of Biological Sciences and Fralin Life Sciences Institute, Virginia Tech, Blacksburg, VA 24061, USA
| | - Janina Müller
- Department of Biological Sciences and Fralin Life Sciences Institute, Virginia Tech, Blacksburg, VA 24061, USA
| | - Silke Hauf
- Department of Biological Sciences and Fralin Life Sciences Institute, Virginia Tech, Blacksburg, VA 24061, USA.
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17
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Lara-Gonzalez P, Pines J, Desai A. Spindle assembly checkpoint activation and silencing at kinetochores. Semin Cell Dev Biol 2021; 117:86-98. [PMID: 34210579 PMCID: PMC8406419 DOI: 10.1016/j.semcdb.2021.06.009] [Citation(s) in RCA: 105] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 06/17/2021] [Accepted: 06/17/2021] [Indexed: 01/01/2023]
Abstract
The spindle assembly checkpoint (SAC) is a surveillance mechanism that promotes accurate chromosome segregation in mitosis. The checkpoint senses the attachment state of kinetochores, the proteinaceous structures that assemble onto chromosomes in mitosis in order to mediate their interaction with spindle microtubules. When unattached, kinetochores generate a diffusible inhibitor that blocks the activity of the anaphase-promoting complex/cyclosome (APC/C), an E3 ubiquitin ligase required for sister chromatid separation and exit from mitosis. Work from the past decade has greatly illuminated our understanding of the mechanisms by which the diffusible inhibitor is assembled and how it inhibits the APC/C. However, less is understood about how SAC proteins are recruited to kinetochores in the absence of microtubule attachment, how the kinetochore catalyzes formation of the diffusible inhibitor, and how attachments silence the SAC at the kinetochore. Here, we summarize current understanding of the mechanisms that activate and silence the SAC at kinetochores and highlight open questions for future investigation.
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Affiliation(s)
- Pablo Lara-Gonzalez
- Ludwig Institute for Cancer Research, USA; Department of Cellular & Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA.
| | | | - Arshad Desai
- Ludwig Institute for Cancer Research, USA; Department of Cellular & Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA.
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18
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Kops GJPL, Snel B, Tromer EC. Evolutionary Dynamics of the Spindle Assembly Checkpoint in Eukaryotes. Curr Biol 2021; 30:R589-R602. [PMID: 32428500 DOI: 10.1016/j.cub.2020.02.021] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The tremendous diversity in eukaryotic life forms can ultimately be traced back to evolutionary modifications at the level of molecular networks. Deep understanding of these modifications will not only explain cellular diversity, but will also uncover different ways to execute similar processes and expose the evolutionary 'rules' that shape the molecular networks. Here, we review the evolutionary dynamics of the spindle assembly checkpoint (SAC), a signaling network that guards fidelity of chromosome segregation. We illustrate how the interpretation of divergent SAC systems in eukaryotic species is facilitated by combining detailed molecular knowledge of the SAC and extensive comparative genome analyses. Ultimately, expanding this to other core cellular systems and experimentally interrogating such systems in organisms from all major lineages may start outlining the routes to and eventual manifestation of the cellular diversity of eukaryotic life.
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Affiliation(s)
- Geert J P L Kops
- Oncode Institute, Hubrecht Institute - KNAW (Royal Netherlands Academy of Arts and Sciences) and University Medical Centre Utrecht, Utrecht, The Netherlands.
| | - Berend Snel
- Theoretical Biology and Bioinformatics, Department of Biology, Science Faculty, Utrecht University, Utrecht, The Netherlands.
| | - Eelco C Tromer
- Department of Biochemistry, University of Cambridge, Cambridge, UK.
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19
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Klingel V, Kirch J, Ullrich T, Weirich S, Jeltsch A, Radde NE. Model-based robustness and bistability analysis for methylation-based, epigenetic memory systems. FEBS J 2021; 288:5692-5707. [PMID: 33774905 DOI: 10.1111/febs.15838] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 03/12/2021] [Accepted: 03/23/2021] [Indexed: 01/08/2023]
Abstract
In recent years, epigenetic memory systems have been developed based on DNA methylation and positive feedback systems. Achieving a robust design for these systems is generally a challenging and multifactorial task. We developed and validated a novel mathematical model to describe methylation-based epigenetic memory systems that capture switching dynamics of methylation levels and methyltransferase amounts induced by different inputs. A bifurcation analysis shows that the system operates in the bistable range, but in its current setup is not robust to changes in parameters. An expansion of the model captures heterogeneity of cell populations by accounting for distributed cell division rates. Simulations predict that the system is highly sensitive to variations in temperature, which affects cell division and the efficiency of the zinc finger repressor. A moderate decrease in temperature leads to a highly heterogeneous response to input signals and bistability on a single-cell level. The predictions of our model were confirmed by flow cytometry experiments conducted in this study. Overall, the results of our study give insights into the functional mechanisms of methylation-based memory systems and demonstrate that the switching dynamics can be highly sensitive to experimental conditions.
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Affiliation(s)
- Viviane Klingel
- Institute for Systems Theory and Automatic Control, University of Stuttgart, Germany
| | - Jakob Kirch
- Institute for Systems Theory and Automatic Control, University of Stuttgart, Germany
| | - Timo Ullrich
- Institute of Biochemistry and Technical Biochemistry, University of Stuttgart, Germany
| | - Sara Weirich
- Institute of Biochemistry and Technical Biochemistry, University of Stuttgart, Germany
| | - Albert Jeltsch
- Institute of Biochemistry and Technical Biochemistry, University of Stuttgart, Germany
| | - Nicole E Radde
- Institute for Systems Theory and Automatic Control, University of Stuttgart, Germany
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20
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Singh P, Pesenti ME, Maffini S, Carmignani S, Hedtfeld M, Petrovic A, Srinivasamani A, Bange T, Musacchio A. BUB1 and CENP-U, Primed by CDK1, Are the Main PLK1 Kinetochore Receptors in Mitosis. Mol Cell 2021; 81:67-87.e9. [PMID: 33248027 PMCID: PMC7837267 DOI: 10.1016/j.molcel.2020.10.040] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 09/08/2020] [Accepted: 10/28/2020] [Indexed: 02/02/2023]
Abstract
Reflecting its pleiotropic functions, Polo-like kinase 1 (PLK1) localizes to various sub-cellular structures during mitosis. At kinetochores, PLK1 contributes to microtubule attachments and mitotic checkpoint signaling. Previous studies identified a wealth of potential PLK1 receptors at kinetochores, as well as requirements for various mitotic kinases, including BUB1, Aurora B, and PLK1 itself. Here, we combine ectopic localization, in vitro reconstitution, and kinetochore localization studies to demonstrate that most and likely all of the PLK1 is recruited through BUB1 in the outer kinetochore and centromeric protein U (CENP-U) in the inner kinetochore. BUB1 and CENP-U share a constellation of sequence motifs consisting of a putative PP2A-docking motif and two neighboring PLK1-docking sites, which, contingent on priming phosphorylation by cyclin-dependent kinase 1 and PLK1 itself, bind PLK1 and promote its dimerization. Our results rationalize previous observations and describe a unifying mechanism for recruitment of PLK1 to human kinetochores.
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Affiliation(s)
- Priyanka Singh
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
| | - Marion E Pesenti
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
| | - Stefano Maffini
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
| | - Sara Carmignani
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
| | - Marius Hedtfeld
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
| | - Arsen Petrovic
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
| | - Anupallavi Srinivasamani
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
| | - Tanja Bange
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
| | - Andrea Musacchio
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany; Centre for Medical Biotechnology, Faculty of Biology, University Duisburg-Essen, Universitätsstrasse, 45141 Essen, Germany.
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21
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Audett MR, Maresca TJ. The whole is greater than the sum of its parts: at the intersection of order, disorder, and kinetochore function. Essays Biochem 2020; 64:349-358. [PMID: 32756877 PMCID: PMC8011995 DOI: 10.1042/ebc20190069] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 07/03/2020] [Accepted: 07/07/2020] [Indexed: 11/17/2022]
Abstract
The kinetochore (KT) field has matured tremendously since Earnshaw first identified CENP-A, CENP-B, and CENP-C [1,2]. In the past 35 years, the accumulation of knowledge has included: defining the parts list, identifying epistatic networks of interdependence within the parts list, understanding the spatial organization of subcomplexes into a massive structure - hundreds of megadaltons in size, and dissecting the functions of the KT in its entirety as well as of its individual parts. Like nearly all cell and molecular biology fields, the structure-function paradigm has been foundational to advances in the KT field. A point nicely highlighted by the fact that we are at the precipice of the in vitro reconstitution of a functional KT holo complex. Yet conventional notions of structure cannot provide a complete picture of the KT especially since it contains an abundance of unstructured or intrinsically disordered constituents. The combination of structured and disordered proteins within the KT results in an assembled system that is functionally greater than the sum of its parts.
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Affiliation(s)
- Margaux R Audett
- Biology Department, University of Massachusetts, Amherst, MA, U.S.A
| | - Thomas J Maresca
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, MA, U.S.A
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22
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Size-Dependent Increase in RNA Polymerase II Initiation Rates Mediates Gene Expression Scaling with Cell Size. Curr Biol 2020; 30:1217-1230.e7. [DOI: 10.1016/j.cub.2020.01.053] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 12/01/2019] [Accepted: 01/16/2020] [Indexed: 12/19/2022]
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23
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Wang Y, Wang F, He J, Du J, Zhang H, Shi H, Chen Y, Wei Y, Xue W, Yan J, Feng Y, Gao Y, Li D, Han J, Zhang J. miR-30a-3p Targets MAD2L1 and Regulates Proliferation of Gastric Cancer Cells. Onco Targets Ther 2019; 12:11313-11324. [PMID: 31908496 PMCID: PMC6927793 DOI: 10.2147/ott.s222854] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 11/27/2019] [Indexed: 12/24/2022] Open
Abstract
Purpose This study was done to investigate the inhibition effects of miR-30a-3p on mitotic arrest deficient 2 like 1 (MAD2L1) expression and the proliferation of gastric cancer cells. Patients and methods Cluster analysis and the TCGA database were used to screen the key genes highly expressed in gastric cancer. Based on the LinkedOmics website, the correlation between the miR-30a-3p and the cell cycle-related target gene MAD2L1 in gastric cancer was analyzed. The mRNA and protein expression levels were detected with the quantitative real-time PCR and Western blot analysis. The cell proliferation and cell cycle were also detected and analyzed. Results Bioinformatics analysis showed that MAD2L1 was highly expressed in tumor tissues compared with normal tissues. Compared with normal tissues, the miR-30a-3p was significantly decreased in the gastric cancer tissues. Moreover, MAD2L1 was significantly negatively correlated with the miR-30a-3p expression. Furthermore, over-expression of miR-30a-3p decreased the expression of MAD2L1 at the protein level, which inhibited the proliferation of AGS and BGC-823 gastric cancer cells. In addition, the cell cycles of AGS and BGC-823 cells were arrested at the G0/G1 phase. Conclusion MAD2L1 is a pro-oncogene which is up-regulated in gastric cancer. The miR-30a-3p can down-regulate the MAD2L1 expression, inhibiting the proliferation of gastric cancer cells and affect the cell cycle.
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Affiliation(s)
- Yu Wang
- Department of Clinical Medicine, Medical College of Yan'an University, Yan'an, Shaanxi 716000, People's Republic of China.,Yan'an Key Laboratory of Chronic Disease Prevention and Research, Yan'an, Shaanxi 716000, People's Republic of China
| | - Fenghui Wang
- Department of Clinical Medicine, Medical College of Yan'an University, Yan'an, Shaanxi 716000, People's Republic of China.,Yan'an Key Laboratory of Chronic Disease Prevention and Research, Yan'an, Shaanxi 716000, People's Republic of China
| | - Jing He
- Department of Clinical Medicine, Medical College of Yan'an University, Yan'an, Shaanxi 716000, People's Republic of China.,Yan'an Key Laboratory of Chronic Disease Prevention and Research, Yan'an, Shaanxi 716000, People's Republic of China
| | - Juan Du
- Department of Clinical Medicine, Medical College of Yan'an University, Yan'an, Shaanxi 716000, People's Republic of China.,Yan'an Key Laboratory of Chronic Disease Prevention and Research, Yan'an, Shaanxi 716000, People's Republic of China
| | - Huahua Zhang
- Department of Clinical Medicine, Medical College of Yan'an University, Yan'an, Shaanxi 716000, People's Republic of China.,Yan'an Key Laboratory of Chronic Disease Prevention and Research, Yan'an, Shaanxi 716000, People's Republic of China
| | - Haiyan Shi
- Department of Clinical Medicine, Medical College of Yan'an University, Yan'an, Shaanxi 716000, People's Republic of China.,Yan'an Key Laboratory of Chronic Disease Prevention and Research, Yan'an, Shaanxi 716000, People's Republic of China
| | - Yani Chen
- Department of Clinical Medicine, Medical College of Yan'an University, Yan'an, Shaanxi 716000, People's Republic of China.,Yan'an Key Laboratory of Chronic Disease Prevention and Research, Yan'an, Shaanxi 716000, People's Republic of China
| | - Yameng Wei
- Department of Clinical Medicine, Medical College of Yan'an University, Yan'an, Shaanxi 716000, People's Republic of China.,Yan'an Key Laboratory of Chronic Disease Prevention and Research, Yan'an, Shaanxi 716000, People's Republic of China
| | - Wanjuan Xue
- Department of Clinical Medicine, Medical College of Yan'an University, Yan'an, Shaanxi 716000, People's Republic of China.,Yan'an Key Laboratory of Chronic Disease Prevention and Research, Yan'an, Shaanxi 716000, People's Republic of China
| | - Jing Yan
- Department of Clinical Medicine, Medical College of Yan'an University, Yan'an, Shaanxi 716000, People's Republic of China.,Yan'an Key Laboratory of Chronic Disease Prevention and Research, Yan'an, Shaanxi 716000, People's Republic of China
| | - Yun Feng
- Department of Clinical Medicine, Medical College of Yan'an University, Yan'an, Shaanxi 716000, People's Republic of China.,Yan'an Key Laboratory of Chronic Disease Prevention and Research, Yan'an, Shaanxi 716000, People's Republic of China
| | - Yi Gao
- Department of Clinical Medicine, Medical College of Yan'an University, Yan'an, Shaanxi 716000, People's Republic of China.,Yan'an Key Laboratory of Chronic Disease Prevention and Research, Yan'an, Shaanxi 716000, People's Republic of China
| | - Dan Li
- Department of Clinical Medicine, Medical College of Yan'an University, Yan'an, Shaanxi 716000, People's Republic of China.,Yan'an Key Laboratory of Chronic Disease Prevention and Research, Yan'an, Shaanxi 716000, People's Republic of China
| | - Jiming Han
- Department of Clinical Medicine, Medical College of Yan'an University, Yan'an, Shaanxi 716000, People's Republic of China.,Yan'an Key Laboratory of Chronic Disease Prevention and Research, Yan'an, Shaanxi 716000, People's Republic of China
| | - Jing Zhang
- Department of Clinical Medicine, Medical College of Yan'an University, Yan'an, Shaanxi 716000, People's Republic of China.,Yan'an Key Laboratory of Chronic Disease Prevention and Research, Yan'an, Shaanxi 716000, People's Republic of China
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24
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Ding DQ, Okamasa K, Katou Y, Oya E, Nakayama JI, Chikashige Y, Shirahige K, Haraguchi T, Hiraoka Y. Chromosome-associated RNA-protein complexes promote pairing of homologous chromosomes during meiosis in Schizosaccharomyces pombe. Nat Commun 2019; 10:5598. [PMID: 31811152 PMCID: PMC6898681 DOI: 10.1038/s41467-019-13609-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 11/18/2019] [Indexed: 01/07/2023] Open
Abstract
Pairing of homologous chromosomes in meiosis is essential for sexual reproduction. We have previously demonstrated that the fission yeast sme2 RNA, a meiosis-specific long noncoding RNA (lncRNA), accumulates at the sme2 chromosomal loci and mediates their robust pairing in meiosis. However, the mechanisms underlying lncRNA-mediated homologous pairing have remained elusive. In this study, we identify conserved RNA-binding proteins that are required for robust pairing of homologous chromosomes. These proteins accumulate mainly at the sme2 and two other chromosomal loci together with meiosis-specific lncRNAs transcribed from these loci. Remarkably, the chromosomal accumulation of these lncRNA–protein complexes is required for robust pairing. Moreover, the lncRNA–protein complexes exhibit phase separation properties, since 1,6-hexanediol treatment reversibly disassembled these complexes and disrupted the pairing of associated loci. We propose that lncRNA–protein complexes assembled at specific chromosomal loci mediate recognition and subsequent pairing of homologous chromosomes. During meiosis, pairing of homologous chromosomes is critical for sexual reproduction. Here the authors reveal in S. pombe the role of lncRNA–protein complexes during the pairing of homologues chromosomes that assemble at specific chromosomal loci to mediate recognition of the pairs.
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Affiliation(s)
- Da-Qiao Ding
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, 651-2492, Japan.
| | - Kasumi Okamasa
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, 651-2492, Japan
| | - Yuki Katou
- Institute for Quantitative Biosciences, The University of Tokyo, Tokyo, 113-0032, Japan
| | - Eriko Oya
- Graduate School of Natural Sciences, Nagoya City University, Nagoya, 467-8501, Japan.,Faculty of Science and Engineering, Chuo University, Tokyo, 112-8551, Japan
| | - Jun-Ichi Nakayama
- Graduate School of Natural Sciences, Nagoya City University, Nagoya, 467-8501, Japan.,Division of Chromatin Regulation, National Institute for Basic Biology, Okazaki, 444-8585, Japan
| | - Yuji Chikashige
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, 651-2492, Japan
| | - Katsuhiko Shirahige
- Institute for Quantitative Biosciences, The University of Tokyo, Tokyo, 113-0032, Japan
| | - Tokuko Haraguchi
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, 651-2492, Japan.,Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan
| | - Yasushi Hiraoka
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, 651-2492, Japan. .,Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan.
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25
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The mammalian kinetochore-microtubule interface: robust mechanics and computation with many microtubules. Curr Opin Cell Biol 2019; 60:60-67. [PMID: 31132675 DOI: 10.1016/j.ceb.2019.04.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 04/10/2019] [Accepted: 04/15/2019] [Indexed: 12/31/2022]
Abstract
The kinetochore drives chromosome segregation at cell division. It acts as a physical link between chromosomes and dynamic microtubules, and as a signaling hub detecting and processing microtubule attachments to control anaphase onset. The mammalian kinetochore is a large macromolecular machine that forms a dynamic interface with the many microtubules that it binds. While we know most of the kinetochore's component parts, how they work together to give rise to its robust functions remains poorly understood. Here we highlight recent findings that shed light on this question, driven by an expanding physical and molecular toolkit. We present emerging principles that underlie the kinetochore's robust microtubule grip, such as redundancy, specialization, and dynamicity, and present signal processing principles that connect this microtubule grip to robust computation. Throughout, we identify open questions, and define simple engineering concepts that provide insight into kinetochore function.
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26
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French BT, Straight AF. The Power of Xenopus Egg Extract for Reconstitution of Centromere and Kinetochore Function. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2019; 56:59-84. [PMID: 28840233 DOI: 10.1007/978-3-319-58592-5_3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Faithful transmission of genetic information during cell division requires attachment of chromosomes to the mitotic spindle via the kinetochore. In vitro reconstitution studies are beginning to uncover how the kinetochore is assembled upon the underlying centromere, how the kinetochore couples chromosome movement to microtubule dynamics, and how cells ensure the site of kinetochore assembly is maintained from one generation to the next. Here we give special emphasis to advances made in Xenopus egg extract, which provides a unique, biochemically tractable in vitro system that affords the complexity of cytoplasm and nucleoplasm to permit reconstitution of the dynamic, cell cycle-regulated functions of the centromere and kinetochore.
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Affiliation(s)
- Bradley T French
- Department of Biochemistry, Stanford University, 279 Campus Drive, Beckman 409, Stanford, CA, 94305, USA
| | - Aaron F Straight
- Department of Biochemistry, Stanford University, 279 Campus Drive, Beckman 409, Stanford, CA, 94305, USA.
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27
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Santos LC, Vogel R, Chipuk JE, Birtwistle MR, Stolovitzky G, Meyer P. Mitochondrial origins of fractional control in regulated cell death. Nat Commun 2019; 10:1313. [PMID: 30899020 PMCID: PMC6428895 DOI: 10.1038/s41467-019-09275-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 03/01/2019] [Indexed: 11/09/2022] Open
Abstract
Individual cells in clonal populations often respond differently to environmental changes; for binary phenotypes, such as cell death, this can be measured as a fractional response. These types of responses have been attributed to cell-intrinsic stochastic processes and variable abundances of biochemical constituents, such as proteins, but the influence of organelles is still under investigation. We use the response to TNF-related apoptosis inducing ligand (TRAIL) and a new statistical framework for determining parameter influence on cell-to-cell variability through the inference of variance explained, DEPICTIVE, to demonstrate that variable mitochondria abundance correlates with cell survival and determines the fractional cell death response. By quantitative data analysis and modeling we attribute this effect to variable effective concentrations at the mitochondria surface of the pro-apoptotic proteins Bax/Bak. Further, our study suggests that inhibitors of anti-apoptotic Bcl-2 family proteins, used in cancer treatment, may increase the diversity of cellular responses, enhancing resistance to treatment. Phenotypic cell-to-cell variability contributes to fractional killing, but the mechanisms are incompletely understood. Here the authors show that mitochondrial density correlates with cell survival in response to TRAIL, and that variable effective concentrations of Bax/Bak contribute to the effect.
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Affiliation(s)
- Luís C Santos
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Robert Vogel
- IBM T.J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY, 10598, USA.,Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Jerry E Chipuk
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.,The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, New York, NY, 10029, USA
| | - Marc R Birtwistle
- Systems Biology Center New York, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA. .,Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC, 29634, USA.
| | - Gustavo Stolovitzky
- IBM T.J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY, 10598, USA. .,Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.
| | - Pablo Meyer
- IBM T.J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY, 10598, USA. .,Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.
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28
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Chen C, Whitney IP, Banerjee A, Sacristan C, Sekhri P, Kern DM, Fontan A, Kops GJPL, Tyson JJ, Cheeseman IM, Joglekar AP. Ectopic Activation of the Spindle Assembly Checkpoint Signaling Cascade Reveals Its Biochemical Design. Curr Biol 2018; 29:104-119.e10. [PMID: 30595520 DOI: 10.1016/j.cub.2018.11.054] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 11/13/2018] [Accepted: 11/21/2018] [Indexed: 11/27/2022]
Abstract
Switch-like activation of the spindle assembly checkpoint (SAC) is critical for accurate chromosome segregation and for cell division in a timely manner. To determine the mechanisms that achieve this, we engineered an ectopic, kinetochore-independent SAC activator: the "eSAC." The eSAC stimulates SAC signaling by artificially dimerizing Mps1 kinase domain and a cytosolic KNL1 phosphodomain, the kinetochore signaling scaffold. By exploiting variable eSAC expression in a cell population, we defined the dependence of the eSAC-induced mitotic delay on eSAC concentration in a cell to reveal the dose-response behavior of the core signaling cascade of the SAC. These quantitative analyses and subsequent mathematical modeling of the dose-response data uncover two crucial properties of the core SAC signaling cascade: (1) a cellular limit on the maximum anaphase-inhibitory signal that the cascade can generate due to the limited supply of SAC proteins and (2) the ability of the KNL1 phosphodomain to produce the anaphase-inhibitory signal synergistically, when it recruits multiple SAC proteins simultaneously. We propose that these properties together achieve inverse, non-linear scaling between the signal output per kinetochore and the number of signaling kinetochores. When the number of kinetochores is low, synergistic signaling by KNL1 enables each kinetochore to produce a disproportionately strong signal output. However, when many kinetochores signal concurrently, they compete for a limited supply of SAC proteins. This frustrates synergistic signaling and lowers their signal output. Thus, the signaling activity of unattached kinetochores will adapt to the changing number of signaling kinetochores to enable the SAC to approximate switch-like behavior.
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Affiliation(s)
- Chu Chen
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Ian P Whitney
- Whitehead Institute for Biomedical Research and Department of Biology, MIT, Nine Cambridge Center, Cambridge, MA 02142, USA
| | - Anand Banerjee
- Department of Biological Sciences, Virginia Polytechnic Institute & State University, Blacksburg, VA 24061, USA
| | - Carlos Sacristan
- Hubrecht Institute - KNAW (Royal Netherlands Academy of Arts and Sciences), and Molecular Cancer Research, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Palak Sekhri
- Cell & Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - David M Kern
- Whitehead Institute for Biomedical Research and Department of Biology, MIT, Nine Cambridge Center, Cambridge, MA 02142, USA
| | - Adrienne Fontan
- Cell & Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Geert J P L Kops
- Hubrecht Institute - KNAW (Royal Netherlands Academy of Arts and Sciences), and Molecular Cancer Research, University Medical Center Utrecht, Utrecht, the Netherlands
| | - John J Tyson
- Department of Biological Sciences, Virginia Polytechnic Institute & State University, Blacksburg, VA 24061, USA
| | - Iain M Cheeseman
- Whitehead Institute for Biomedical Research and Department of Biology, MIT, Nine Cambridge Center, Cambridge, MA 02142, USA
| | - Ajit P Joglekar
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA; Cell & Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
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29
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Gross F, Bonaiuti P, Hauf S, Ciliberto A. Implications of alternative routes to APC/C inhibition by the mitotic checkpoint complex. PLoS Comput Biol 2018; 14:e1006449. [PMID: 30199529 PMCID: PMC6157902 DOI: 10.1371/journal.pcbi.1006449] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 09/26/2018] [Accepted: 08/20/2018] [Indexed: 01/19/2023] Open
Abstract
The mitotic checkpoint (also called spindle assembly checkpoint) is a signaling pathway that ensures faithful chromosome segregation. Mitotic checkpoint proteins inhibit the anaphase-promoting complex (APC/C) and its activator Cdc20 to prevent precocious anaphase. Checkpoint signaling leads to a complex of APC/C, Cdc20, and checkpoint proteins, in which the APC/C is inactive. In principle, this final product of the mitotic checkpoint can be obtained via different pathways, whose relevance still needs to be fully ascertained experimentally. Here, we use mathematical models to compare the implications on checkpoint response of the possible pathways leading to APC/C inhibition. We identify a previously unrecognized funneling effect for Cdc20, which favors Cdc20 incorporation into the inhibitory complex and therefore promotes checkpoint activity. Furthermore, we find that the presence or absence of one specific assembly reaction determines whether the checkpoint remains functional at elevated levels of Cdc20, which can occur in cancer cells. Our results reveal the inhibitory logics behind checkpoint activity, predict checkpoint efficiency in perturbed situations, and could inform molecular strategies to treat malignancies that exhibit Cdc20 overexpression. Cell division is a fundamental event in the life of cells. It requires that a mother cell gives rise to two daughters which carry the same genetic material of their mother. Thus, during each cell cycle the genetic material needs to be replicated, compacted into chromosomes and redistributed to the two daughter cells. Any mistake in chromosome segregation would attribute the wrong number of chromosomes to the progeny. Hence, the process of chromosome segregation is closely watched by a surveillance mechanism known as the mitotic checkpoint. The molecular players of the checkpoint pathway are well known: we know both the input (ie, the species to be inhibited and their inhibitors), and the output (ie, the inhibited species). However, we do not exactly know the path that leads from the former to the latter. In this manuscript, we use a mathematical approach to explore the properties of plausible mitotic checkpoint networks. We find that seemingly similar circuits show very different behaviors for high levels of the protein targeted by the mitotic checkpoint, Cdc20. Interestingly, this protein is often overexpressed in cancer cells. For physiological levels of Cdc20, instead, all the models we have analyzed are capable to mount an efficient response. We find that this is due to a series of consecutive protein-protein binding reactions that funnel Cdc20 towards its inhibited state. We call this the funneling effect. Our analysis helps understanding the inhibitory logics underlying the checkpoint, and proposes new concepts that could be applied to other inhibitory pathways.
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Affiliation(s)
- Fridolin Gross
- Istituto Firc di Oncologia Molecolare, IFOM, Milano, Italy
| | - Paolo Bonaiuti
- Istituto Firc di Oncologia Molecolare, IFOM, Milano, Italy
| | - Silke Hauf
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, United States of America
- Biocomplexity Institute, Virginia Tech, Blacksburg, VA, United States of America
- Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, United States of America
- * E-mail: (SH); (AC)
| | - Andrea Ciliberto
- Istituto Firc di Oncologia Molecolare, IFOM, Milano, Italy
- Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerche (IGM-CNR), Pavia, Italy
- * E-mail: (SH); (AC)
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30
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Chee MJY, Lycett GW, Chin CF. Development of a direct transformation method by GFP screening and in vitro whole plant regeneration of Capsicum frutescens L. ELECTRON J BIOTECHN 2018. [DOI: 10.1016/j.ejbt.2018.05.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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31
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Shichino Y, Otsubo Y, Kimori Y, Yamamoto M, Yamashita A. YTH-RNA-binding protein prevents deleterious expression of meiotic proteins by tethering their mRNAs to nuclear foci. eLife 2018; 7:32155. [PMID: 29424342 PMCID: PMC5807050 DOI: 10.7554/elife.32155] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 01/31/2018] [Indexed: 12/24/2022] Open
Abstract
Accurate and extensive regulation of meiotic gene expression is crucial to distinguish germ cells from somatic cells. In the fission yeast Schizosaccharomyces pombe, a YTH family RNA-binding protein, Mmi1, directs the nuclear exosome-mediated elimination of meiotic transcripts during vegetative proliferation. Mmi1 also induces the formation of facultative heterochromatin at a subset of its target genes. Here, we show that Mmi1 prevents the mistimed expression of meiotic proteins by tethering their mRNAs to the nuclear foci. Mmi1 interacts with itself with the assistance of a homolog of Enhancer of Rudimentary, Erh1. Mmi1 self-interaction is required for foci formation, target transcript elimination, their nuclear retention, and protein expression inhibition. We propose that nuclear foci formed by Mmi1 are not only the site of RNA degradation, but also of sequestration of meiotic transcripts from the translation machinery.
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Affiliation(s)
- Yuichi Shichino
- Laboratory of Cell Responses, National Institute for Basic Biology, Okazaki, Japan
| | - Yoko Otsubo
- Laboratory of Cell Responses, National Institute for Basic Biology, Okazaki, Japan
| | - Yoshitaka Kimori
- Department of Imaging Science, Center for Novel Science Initiatives, National Institutes of Natural Sciences, Okazaki, Japan.,Laboratory of Biological Diversity, National Institute for Basic Biology, Okazaki, Japan.,Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Japan
| | - Masayuki Yamamoto
- Laboratory of Cell Responses, National Institute for Basic Biology, Okazaki, Japan.,Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Japan
| | - Akira Yamashita
- Laboratory of Cell Responses, National Institute for Basic Biology, Okazaki, Japan.,Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Japan
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32
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Borges DDP, Dos Santos AWA, Paier CRK, Ribeiro HL, Costa MB, Farias IR, de Oliveira RTG, França IGDF, Cavalcante GM, Magalhães SMM, Pinheiro RF. Prognostic importance of Aurora Kinases and mitotic spindle genes transcript levels in Myelodysplastic syndrome. Leuk Res 2017; 64:61-70. [PMID: 29220700 DOI: 10.1016/j.leukres.2017.11.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 11/22/2017] [Accepted: 11/27/2017] [Indexed: 12/25/2022]
Abstract
Myelodysplastic syndrome (MDS) are a heterogeneous group of clonal disease characterized by insufficiency of bone marrow, increase of apoptosis and increased risk of acute leukemia progression. Proteins related to the mitotic spindle (AURKA, AURKB, TPX2), to the mitotic checkpoint (MAD2, CDC20) and the regulation of the cell cycle (p21) are directly related to chromosomal stability and tumor development. This study aimed to evaluate the mRNA expression levels of these genes in 101 MDS patients using a real-time PCR methodology. We identified that CDC20 expression are increased in patients with dysmegakaryopoiesis (p=0.024), thrombocytopenia (p=0.000) and high-risk patients (p=0.014, 0.018) MAD2 expression are decreased in patients with 2 or 3 cytopenias (p=0.000) and neutrophil below 800/mm3. TPX2 is also overexpressed in patients presenting dysmegakaryopoiesis (p=0.009). A decrease in AURKA and AURKB expression were observed in patients with altered karyotype (p=0.000), who presented dysplasia in 3 lineages (p=0.000; 0.017) and hemoglobin inferior to 8g/dL (p=0.024). The expression of AURKA, AURKB and MAD2 (p=0.000; 0.001; 0.025) were decreased in patients with hypoplastic MDS, associated with high frequency of chromosomal alterations and high mortality rate. This study reaffirms the importance of aurora kinases and mitotic spindle genes to the pathogenesis and clinical evolution of MDS.
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Affiliation(s)
- Daniela de Paula Borges
- Cancer Cytogenomic Laboratory, Federal University of Ceara, Fortaleza, Ceara, Brazil; Post-Graduate Program in Medical Science, Federal University of Ceara, Fortaleza, Ceara, Brazil; Center for Research and Drug Development (NPDM), Federal University of Ceara, Fortaleza, Ceara, Brazil
| | - Antônio Wesley Araújo Dos Santos
- Cancer Cytogenomic Laboratory, Federal University of Ceara, Fortaleza, Ceara, Brazil; Center for Research and Drug Development (NPDM), Federal University of Ceara, Fortaleza, Ceara, Brazil
| | | | - Howard Lopes Ribeiro
- Cancer Cytogenomic Laboratory, Federal University of Ceara, Fortaleza, Ceara, Brazil; Post-Graduate Program in Medical Science, Federal University of Ceara, Fortaleza, Ceara, Brazil; Center for Research and Drug Development (NPDM), Federal University of Ceara, Fortaleza, Ceara, Brazil
| | - Marília Braga Costa
- Cancer Cytogenomic Laboratory, Federal University of Ceara, Fortaleza, Ceara, Brazil; Post-Graduate Program in Medical Science, Federal University of Ceara, Fortaleza, Ceara, Brazil; Center for Research and Drug Development (NPDM), Federal University of Ceara, Fortaleza, Ceara, Brazil
| | - Izabelle Rocha Farias
- Cancer Cytogenomic Laboratory, Federal University of Ceara, Fortaleza, Ceara, Brazil; Post-Graduate Program in Medical Science, Federal University of Ceara, Fortaleza, Ceara, Brazil; Center for Research and Drug Development (NPDM), Federal University of Ceara, Fortaleza, Ceara, Brazil
| | - Roberta Taiane Germano de Oliveira
- Cancer Cytogenomic Laboratory, Federal University of Ceara, Fortaleza, Ceara, Brazil; Post-Graduate Program in Medical Science, Federal University of Ceara, Fortaleza, Ceara, Brazil; Center for Research and Drug Development (NPDM), Federal University of Ceara, Fortaleza, Ceara, Brazil
| | - Ivo Gabriel da Frota França
- Cancer Cytogenomic Laboratory, Federal University of Ceara, Fortaleza, Ceara, Brazil; Center for Research and Drug Development (NPDM), Federal University of Ceara, Fortaleza, Ceara, Brazil
| | - Gabrielle Melo Cavalcante
- Cancer Cytogenomic Laboratory, Federal University of Ceara, Fortaleza, Ceara, Brazil; Center for Research and Drug Development (NPDM), Federal University of Ceara, Fortaleza, Ceara, Brazil
| | - Sílvia Maria Meira Magalhães
- Cancer Cytogenomic Laboratory, Federal University of Ceara, Fortaleza, Ceara, Brazil; Post-Graduate Program in Medical Science, Federal University of Ceara, Fortaleza, Ceara, Brazil; Center for Research and Drug Development (NPDM), Federal University of Ceara, Fortaleza, Ceara, Brazil
| | - Ronald Feitosa Pinheiro
- Cancer Cytogenomic Laboratory, Federal University of Ceara, Fortaleza, Ceara, Brazil; Post-Graduate Program in Medical Science, Federal University of Ceara, Fortaleza, Ceara, Brazil; Center for Research and Drug Development (NPDM), Federal University of Ceara, Fortaleza, Ceara, Brazil; Post-Graduate Program of Pathology, Federal University of Ceara, Fortaleza, Ceara, Brazil.
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33
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Lane SIR, Jones KT. Chromosome biorientation and APC activity remain uncoupled in oocytes with reduced volume. J Cell Biol 2017; 216:3949-3957. [PMID: 28978643 PMCID: PMC5716262 DOI: 10.1083/jcb.201606134] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 07/28/2017] [Accepted: 09/07/2017] [Indexed: 11/23/2022] Open
Abstract
Lane and Jones use serial bisection of mouse oocytes to analyze the influence of cytoplasmic volume on spindle assembly checkpoint function. Volume reduction promotes inhibition of APC but cannot prevent chromosome segregation errors at anaphase. The spindle assembly checkpoint (SAC) prevents chromosome missegregation by coupling anaphase onset with correct chromosome attachment and tension to microtubules. It does this by generating a diffusible signal from free kinetochores into the cytoplasm, inhibiting the anaphase-promoting complex (APC). The volume in which this signal remains effective is unknown. This raises the possibility that cell volume may be the reason the SAC is weak, and chromosome segregation error-prone, in mammalian oocytes. Here, by a process of serial bisection, we analyzed the influence of oocyte volume on the ability of the SAC to inhibit bivalent segregation in meiosis I. We were able to generate oocytes with cytoplasmic volumes reduced by 86% and observed changes in APC activity consistent with increased SAC control. However, bivalent biorientation remained uncoupled from APC activity, leading to error-prone chromosome segregation. We conclude that volume is one factor contributing to SAC weakness in oocytes. However, additional factors likely uncouple chromosome biorientation with APC activity.
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Affiliation(s)
- Simon I R Lane
- Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, UK .,School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia
| | - Keith T Jones
- Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, UK.,School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia
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MiR-200c-5p suppresses proliferation and metastasis of human hepatocellular carcinoma (HCC) via suppressing MAD2L1. Biomed Pharmacother 2017; 92:1038-1044. [PMID: 28609841 DOI: 10.1016/j.biopha.2017.05.092] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 05/22/2017] [Accepted: 05/22/2017] [Indexed: 02/07/2023] Open
Abstract
OBJECTIVE To explore the biological functions of miR-200c-5p/MAD2L1 axis on the proliferation and metastasis of human hepatocellular carcinoma (HCC) cells. METHODS The expression levels of miR-200c-5p and MAD2L1 in HCC tissues, adjacent tissues as well as HCC cell lines were detected by RT-qPCR or Western blot. The interaction between miR-200c-5p and MAD2L1 was verified by dual luciferase reporter gene system. Transfection was performed to manipulate the expression of miR-200c-5p and MAD2L1 in HCCLM3 cells. Colony formation, MTT, wound healing and Transwell assays were applied to measure the cell proliferation, migration and invasion of HCC, besides, flow cytometry analysis was also conducted to evaluate HCC cell cycle and apoptosis. RESULTS Low expression of miR-200c-5p and remarkable overexpression of MAD2L1 was uncovered in HCC tissues and cells compared with the normal. The aberrant expression of miR-200c-5p and MAD2L1 was correlated with tumor stage, adjacent organ invasion and prognosis. Direct target relationship between miR-200c-5p and MAD2L1 was confirmed by dual luciferase reporting assay. Up-regulation of miR-200c-5p downregulated MAD2L1 and suppressed the proliferation, migration, invasion and induced apoptosis and cell cycle arrest of HCC cells. Moreover, MAD2L1 promoted HCC cell viabilities and co-transfection of MAD2L1 restored the anti-tumor effects of miR-200c-5p overexpression. CONCLUSION Replenishing of miR-200c-5p inhibited the proliferation, migration and invasion of HCC cells by suppressing MAD2L1. MiR-200c-5p can serve as a prognostic indicator and a promising therapeutic target for HCC patients.
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Kuhn J, Dumont S. Spindle assembly checkpoint satisfaction occurs via end-on but not lateral attachments under tension. J Cell Biol 2017; 216:1533-1542. [PMID: 28536121 PMCID: PMC5461026 DOI: 10.1083/jcb.201611104] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 03/30/2017] [Accepted: 04/26/2017] [Indexed: 11/22/2022] Open
Abstract
To ensure accurate chromosome segregation, the spindle assembly checkpoint (SAC) prevents anaphase until all kinetochores attach to the spindle. What signals the SAC monitors remains unclear. We do not know the contributions of different microtubule attachment features or tension from biorientation to SAC satisfaction nor how these possible cues change during attachment. In this study, we quantify concurrent Mad1 intensity and report on SAC silencing, real-time attachment geometry, occupancy, and tension at individual mammalian kinetochores. We show that Mad1 loss from the kinetochore is switch-like with robust kinetics and that tension across sister kinetochores is established just before Mad1 loss events at the first sister. We demonstrate that CenpE-mediated lateral attachment of the second sister can persistently generate this metaphase-like tension before biorientation, likely stabilizing sister end-on attachment, yet cannot induce Mad1 loss from that kinetochore. Instead, Mad1 loss begins after several end-on microtubules attach. Thus, end-on attachment provides geometry-specific molecular cues or force on specific kinetochore linkages that other attachment geometries cannot provide.
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Affiliation(s)
- Jonathan Kuhn
- Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA.,Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA
| | - Sophie Dumont
- Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA .,Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA.,Department of Cell and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA
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36
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Size-Dependent Expression of the Mitotic Activator Cdc25 Suggests a Mechanism of Size Control in Fission Yeast. Curr Biol 2017; 27:1491-1497.e4. [PMID: 28479325 DOI: 10.1016/j.cub.2017.04.016] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 02/28/2017] [Accepted: 04/11/2017] [Indexed: 01/19/2023]
Abstract
Proper cell size is essential for cellular function. Nonetheless, despite more than 100 years of work on the subject, the mechanisms that maintain cell-size homeostasis are largely mysterious [1]. Cells in growing populations maintain cell size within a narrow range by coordinating growth and division. Bacterial and eukaryotic cells both demonstrate homeostatic size control, which maintains population-level variation in cell size within a certain range and returns the population average to that range if it is perturbed [1, 2]. Recent work has proposed two different strategies for size control: budding yeast has been proposed to use an inhibitor-dilution strategy to regulate size at the G1/S transition [3], whereas bacteria appear to use an adder strategy, in which a fixed amount of growth each generation causes cell size to converge on a stable average [4-6]. Here we present evidence that cell size in the fission yeast Schizosaccharomyces pombe is regulated by a third strategy: the size-dependent expression of the mitotic activator Cdc25. cdc25 transcript levels are regulated such that smaller cells express less Cdc25 and larger cells express more Cdc25, creating an increasing concentration of Cdc25 as cells grow and providing a mechanism for cells to trigger cell division when they reach a threshold concentration of Cdc25. Because regulation of mitotic entry by Cdc25 is well conserved, this mechanism may provide a widespread solution to the problem of size control in eukaryotes.
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37
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May KM, Paldi F, Hardwick KG. Fission Yeast Apc15 Stabilizes MCC-Cdc20-APC/C Complexes, Ensuring Efficient Cdc20 Ubiquitination and Checkpoint Arrest. Curr Biol 2017; 27:1221-1228. [PMID: 28366744 PMCID: PMC5405113 DOI: 10.1016/j.cub.2017.03.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Revised: 03/03/2017] [Accepted: 03/08/2017] [Indexed: 12/16/2022]
Abstract
During mitosis, cells must segregate the replicated copies of their genome to their daughter cells with extremely high fidelity. Segregation errors lead to an abnormal chromosome number (aneuploidy), which typically results in disease or cell death [1]. Chromosome segregation and anaphase onset are initiated through the action of the multi-subunit E3 ubiquitin ligase known as the anaphase-promoting complex or cyclosome (APC/C [2]). The APC/C is inhibited by the spindle checkpoint in the presence of kinetochore attachment defects [3, 4]. Here we demonstrate that two non-essential APC/C subunits (Apc14 and Apc15) regulate association of spindle checkpoint proteins, in the form of the mitotic checkpoint complex (MCC), with the APC/C. apc14Δ mutants display increased MCC association with the APC/C and are unable to silence the checkpoint efficiently. Conversely, apc15Δ mutants display reduced association between the MCC and APC/C, are defective in poly-ubiquitination of Cdc20, and are checkpoint defective. In vitro reconstitution studies have shown that human MCC-APC/C can contain two molecules of Cdc20 [5-7]. Using a yeast strain expressing two Cdc20 genes with different epitope tags, we show by co-immunoprecipitation that this is true in vivo. MCC binding to the second molecule of Cdc20 is mediated via the C-terminal KEN box in Mad3. Somewhat surprisingly, complexes containing both molecules of Cdc20 accumulate in apc15Δ cells, and the implications of this observation are discussed.
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Affiliation(s)
- Karen M May
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Flora Paldi
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Kevin G Hardwick
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, UK.
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38
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Different Functionality of Cdc20 Binding Sites within the Mitotic Checkpoint Complex. Curr Biol 2017; 27:1213-1220. [PMID: 28366743 DOI: 10.1016/j.cub.2017.03.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 02/28/2017] [Accepted: 03/03/2017] [Indexed: 11/21/2022]
Abstract
The mitotic checkpoint is a cellular safeguard that prevents chromosome missegregation in eukaryotic cells [1, 2]. Suboptimal functioning may foster chromosome missegregation in cancer cells [3]. Checkpoint signaling produces the "mitotic checkpoint complex" (MCC), which prevents anaphase by targeting Cdc20, the activator of the anaphase-promoting complex/cyclosome (APC/C). Recent biochemical and structural studies revealed that the human MCC binds two Cdc20 molecules, one (Cdc20M) through well-characterized, cooperative binding to Mad2 and Mad3/BubR1 (forming the "core MCC") and the other one (Cdc20A) through additional binding sequences in Mad3/BubR1 [4-6]. Here, we dissect the different functionality of these sites in vivo. We show in fission yeast that, at low Cdc20 concentrations, Cdc20M binding is sufficient for checkpoint activity and Cdc20A binding becomes dispensable. Cdc20A binding is mediated by the conserved Mad3 ABBA-KEN2-ABBA motif [7, 8], which we find additionally required for binding of the MCC to the APC/C and for MCC disassembly. Strikingly, deletion of the APC/C subunit Apc15 mimics mutations in this motif, revealing a shared function. This function of Apc15 may be masked in human cells by independent mediators of MCC-APC/C binding. Our data provide important in vivo support for the recent structure-based models and functionally dissect three elements of Cdc20 inhibition: (1) sequestration of Cdc20 in the core MCC, sufficient at low Cdc20 concentrations; (2) inhibition of a second Cdc20 through the Mad3 C terminus, independent of Mad2 binding to this Cdc20 molecule; and (3) occupancy of the APC/C with full MCC, where Mad3 and Apc15 are involved.
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39
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Heinrich S, Sidler CL, Azzalin CM, Weis K. Stem-loop RNA labeling can affect nuclear and cytoplasmic mRNA processing. RNA (NEW YORK, N.Y.) 2017; 23:134-141. [PMID: 28096443 PMCID: PMC5238788 DOI: 10.1261/rna.057786.116] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 11/03/2016] [Indexed: 05/17/2023]
Abstract
The binding of sequence-specific RNA-interacting proteins, such as the bacteriophage MS2 or PP7 coat proteins, to their corresponding target sequences has been extremely useful and widely used to visualize single mRNAs in vivo. However, introduction of MS2 stem-loops into yeast mRNAs has recently been shown to lead to the accumulation of RNA fragments, suggesting that the loops impair mRNA decay. This result was questioned, because fragment occurrence was mainly assessed using ensemble methods, and their cellular localization and its implications had not been addressed on a single transcript level. Here, we demonstrate that the introduction of either MS2 stem-loops (MS2SL) or PP7 stem-loops (PP7SL) can affect the processing and subcellular localization of mRNA. We use single-molecule fluorescence in situ hybridization (smFISH) to determine the localization of three independent mRNAs tagged with the stem-loop labeling systems in glucose-rich and glucose starvation conditions. Transcripts containing MS2SL or PP7SL display aberrant localization in both the nucleus and the cytoplasm. These defects are most prominent in glucose starvation conditions, with nuclear mRNA processing being altered and stem-loop fragments abnormally enriching in processing bodies (PBs). The mislocalization of SL-containing RNAs is independent of the presence of the MS2 or PP7 coat protein (MCP or PCP).
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Affiliation(s)
| | | | - Claus M Azzalin
- Institute of Biochemistry, ETH Zurich, 8093 Zurich, Switzerland
| | - Karsten Weis
- Institute of Biochemistry, ETH Zurich, 8093 Zurich, Switzerland
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40
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Inositol Pyrophosphate Kinase Asp1 Modulates Chromosome Segregation Fidelity and Spindle Function in Schizosaccharomyces pombe. Mol Cell Biol 2016; 36:3128-3140. [PMID: 27697865 DOI: 10.1128/mcb.00330-16] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 09/29/2016] [Indexed: 01/08/2023] Open
Abstract
Chromosome transmission fidelity during mitosis is of critical importance for the fitness of an organism, as mistakes will lead to aneuploidy, which has a causative role in numerous severe diseases. Proper segregation of chromosomes depends on interdependent processes at the microtubule-kinetochore interface and the spindle assembly checkpoint. Here we report the discovery of a new element essential for chromosome transmission fidelity that implicates inositol pyrophosphates (IPPs) as playing a key role in this process. The protein is Asp1, the Schizosaccharomyces pombe member of the highly conserved Vip1 family. Vip1 enzymes are bifunctional: they consist of an IPP-generating kinase domain and a pyrophosphatase domain that uses such IPPs as substrates. We show that Asp1 kinase function is required for bipolar spindle formation. The absence of Asp1-generated IPPs resulted in errors in sister chromatid biorientation, a prolonged checkpoint-controlled delay of anaphase onset, and chromosome missegregation. Remarkably, expression of Asp1 variants that generated higher-than-wild-type levels of IPPs led to a faster-than-wild-type entry into anaphase A without an increase in chromosome missegregation. In fact, the chromosome transmission fidelity of a nonessential chromosome was enhanced with increased cellular IPPs. Thus, we identified an element that optimized the wild-type chromosome transmission process.
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41
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Joglekar AP. A Cell Biological Perspective on Past, Present and Future Investigations of the Spindle Assembly Checkpoint. BIOLOGY 2016; 5:biology5040044. [PMID: 27869759 PMCID: PMC5192424 DOI: 10.3390/biology5040044] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 11/10/2016] [Accepted: 11/14/2016] [Indexed: 12/04/2022]
Abstract
The spindle assembly checkpoint (SAC) is a quality control mechanism that ensures accurate chromosome segregation during cell division. It consists of a mechanochemical signal transduction mechanism that senses the attachment of chromosomes to the spindle, and a signaling cascade that inhibits cell division if one or more chromosomes are not attached. Extensive investigations of both these component systems of the SAC have synthesized a comprehensive understanding of the underlying molecular mechanisms. This review recounts the milestone results that elucidated the SAC, compiles a simple model of the complex molecular machinery underlying the SAC, and highlights poorly understood facets of the biochemical design and cell biological operation of the SAC that will drive research forward in the near future.
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Affiliation(s)
- Ajit P Joglekar
- Cell & Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
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42
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Manic G, Corradi F, Sistigu A, Siteni S, Vitale I. Molecular Regulation of the Spindle Assembly Checkpoint by Kinases and Phosphatases. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 328:105-161. [PMID: 28069132 DOI: 10.1016/bs.ircmb.2016.08.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The spindle assembly checkpoint (SAC) is a surveillance mechanism contributing to the preservation of genomic stability by monitoring the microtubule attachment to, and/or the tension status of, each kinetochore during mitosis. The SAC halts metaphase to anaphase transition in the presence of unattached and/or untensed kinetochore(s) by releasing the mitotic checkpoint complex (MCC) from these improperly-oriented kinetochores to inhibit the anaphase-promoting complex/cyclosome (APC/C). The reversible phosphorylation of a variety of substrates at the kinetochore by antagonistic kinases and phosphatases is one major signaling mechanism for promptly turning on or turning off the SAC. In such a complex network, some kinases act at the apex of the SAC cascade by either generating (monopolar spindle 1, MPS1/TTK and likely polo-like kinase 1, PLK1), or contributing to generate (Aurora kinase B) kinetochore phospho-docking sites for the hierarchical recruitment of the SAC proteins. Aurora kinase B, MPS1 and budding uninhibited by benzimidazoles 1 (BUB1) also promote sister chromatid biorientation by modulating kinetochore microtubule stability. Moreover, MPS1, BUB1, and PLK1 seem to play key roles in APC/C inhibition by mechanisms dependent and/or independent on MCC assembly. The protein phosphatase 1 and 2A (PP1 and PP2A) are recruited to kinetochores to oppose kinase activity. These phosphatases reverse the phosphorylation of kinetochore targets promoting the microtubule attachment stabilization, sister kinetochore biorientation and SAC silencing. The kinase-phosphatase network is crucial as it renders the SAC a dynamic, graded-signaling, high responsive, and robust process thereby ensuring timely anaphase onset and preventing the generation of proneoplastic aneuploidy.
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Affiliation(s)
- G Manic
- Regina Elena National Cancer Institute, Rome, Italy.
| | - F Corradi
- Department of Biology, University of Rome "Tor Vergata", Rome, Italy
| | - A Sistigu
- Regina Elena National Cancer Institute, Rome, Italy
| | - S Siteni
- Regina Elena National Cancer Institute, Rome, Italy; Department of Biology, University of Rome "Roma Tre", Rome, Italy
| | - I Vitale
- Regina Elena National Cancer Institute, Rome, Italy; Department of Biology, University of Rome "Tor Vergata", Rome, Italy.
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43
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Miki A, Galipon J, Sawai S, Inada T, Ohta K. RNA decay systems enhance reciprocal switching of sense and antisense transcripts in response to glucose starvation. Genes Cells 2016; 21:1276-1289. [PMID: 27723196 DOI: 10.1111/gtc.12443] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Accepted: 09/13/2016] [Indexed: 02/03/2023]
Abstract
Antisense RNA has emerged as a crucial regulator of opposite-strand protein-coding genes in the long noncoding RNA (lncRNA) category, but little is known about their dynamics and decay process in the context of a stress response. Antisense transcripts from the fission yeast fbp1 locus (fbp1-as) are expressed in glucose-rich conditions and anticorrelated with transcription of metabolic stress-induced lncRNA (mlonRNA) and mRNA on the sense strand during glucose starvation. Here, we investigate the localization and decay of antisense RNAs at fbp1 and other loci, and propose a model to explain the rapid switch between antisense and sense mlonRNA/mRNA transcription triggered by glucose starvation. We show that fbp1-as shares many features with mRNAs, such as a 5'-cap and poly(A)-tail, and that its decay partially depends upon Rrp6, a cofactor of the nuclear exosome complex involved in 3'-5' degradation of RNA. Fluorescence in situ hybridization and polysome fractionation show that the majority of remaining fbp1-as localizes to the cytoplasm and binds to polyribosomes in glucose-rich conditions. Furthermore, fbp1-as and antisense RNA at other stress-responsive loci are promptly degraded via the cotranslational nonsense-mediated decay (NMD) pathway. These results suggest NMD may potentiate the swift disappearance of antisense RNAs in response to cellular stress.
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Affiliation(s)
- Atsuko Miki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8654, Japan
| | - Josephine Galipon
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, 997-0035, Japan
| | - Satoshi Sawai
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan
| | - Toshifumi Inada
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, 980-8578, Japan
| | - Kunihiro Ohta
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8654, Japan.,Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan
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44
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Mugler CF, Hondele M, Heinrich S, Sachdev R, Vallotton P, Koek AY, Chan LY, Weis K. ATPase activity of the DEAD-box protein Dhh1 controls processing body formation. eLife 2016; 5. [PMID: 27692063 PMCID: PMC5096884 DOI: 10.7554/elife.18746] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 09/28/2016] [Indexed: 12/22/2022] Open
Abstract
Translational repression and mRNA degradation are critical mechanisms of posttranscriptional gene regulation that help cells respond to internal and external cues. In response to certain stress conditions, many mRNA decay factors are enriched in processing bodies (PBs), cellular structures involved in degradation and/or storage of mRNAs. Yet, how cells regulate assembly and disassembly of PBs remains poorly understood. Here, we show that in budding yeast, mutations in the DEAD-box ATPase Dhh1 that prevent ATP hydrolysis, or that affect the interaction between Dhh1 and Not1, the central scaffold of the CCR4-NOT complex and an activator of the Dhh1 ATPase, prevent PB disassembly in vivo. Intriguingly, this process can be recapitulated in vitro, since recombinant Dhh1 and RNA, in the presence of ATP, phase-separate into liquid droplets that rapidly dissolve upon addition of Not1. Our results identify the ATPase activity of Dhh1 as a critical regulator of PB formation. DOI:http://dx.doi.org/10.7554/eLife.18746.001 Most cells and organisms live in changeable environments. Adapting to environmental changes means that organisms must quickly alter which of their genes they express. Varying which genes are switched on or off is not enough; cells must also degrade existing messenger RNAs (or mRNAs for short), which contain the genetic instructions of the previously active genes. Therefore, cells must tightly regulate the machinery needed to degrade mRNAs. When Baker’s yeast (also known as budding yeast) cells experience certain stressful conditions, the proteins that break down mRNAs localize into specific structures inside the cell known as ‘processing bodies’. These structures are found in many other organisms across evolution, from yeast to human. Processing bodies also form in a variety of biological contexts, such as in nerve cells and developing embryos. Still, why cells form processing bodies, and how their assembly is regulated, is not well understood. One essential component of processing bodies is an enzyme called Dhh1. This enzyme has been conserved throughout evolution and is known to promote the decay of mRNAs as well as to repress their translation into proteins. Now, Mugler, Hondele et al. show that Dhh1’s must break down molecules of the energy carrier ATP (referred to as its “ATPase activity”) in order to regulate the dynamic nature of processing bodies. Mutant Dhh1 proteins that lack ATPase activity form permanent processing bodies in non-stressed yeast cells. This shows that that the breakdown of ATP by Dhh1 is required for the disassembly of processing bodies. Similar results were seen for mutant Dhh1 proteins that cannot interact with Not1, a protein which enhances the ATPase activity of Dhh1. Next Mugler, Hondele et al. mixed purified Dhh1 with ATP and RNA molecules and saw that the mixture underwent a “liquid-liquid phase separation” and formed observable granules, similar to oil droplets in water. These granules dissolved when Not1 was added to stimulate the Dhh1 enzyme to turnover ATP. This showed that several important biochemical and biophysical aspects of processing bodies seen within living cells could be recreated outside of a cell. Armed with a greater understanding of the rules that govern the formation of processing bodies, future work can now address how important processing bodies are for regulating gene expression. Another challenge for the future will be to examine the specific roles that processing bodies play in yeast and other cells, like human egg cells or nerve cells. DOI:http://dx.doi.org/10.7554/eLife.18746.002
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Affiliation(s)
| | | | | | | | | | - Adriana Y Koek
- University of California, Berkeley, Berkeley, United States
| | - Leon Y Chan
- University of California, Berkeley, Berkeley, United States
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Bub3-Bub1 Binding to Spc7/KNL1 Toggles the Spindle Checkpoint Switch by Licensing the Interaction of Bub1 with Mad1-Mad2. Curr Biol 2016; 26:2642-2650. [PMID: 27618268 DOI: 10.1016/j.cub.2016.07.040] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 06/22/2016] [Accepted: 07/15/2016] [Indexed: 01/06/2023]
Abstract
The spindle assembly checkpoint (SAC) ensures that sister chromatids do not separate until all chromosomes are attached to spindle microtubules and bi-oriented. Spindle checkpoint proteins, including Mad1, Mad2, Mad3 (BubR1), Bub1, Bub3, and Mph1 (Mps1), are recruited to unattached and/or tensionless kinetochores. SAC activation catalyzes the conversion of soluble Mad2 (O-Mad2) into a form (C-Mad2) that binds Cdc20, BubR1, and Bub3 to form the mitotic checkpoint complex (MCC), a potent inhibitor of the anaphase-promoting complex (APC/C). SAC silencing de-represses Cdc20-APC/C activity allowing poly-ubiquitination of Securin and Cyclin B, leading to the dissolution of sister chromatids and anaphase onset [1]. Understanding how microtubule interaction at kinetochores influences the timing of anaphase requires an understanding of how spindle checkpoint protein interaction with the kinetochore influences spindle checkpoint signaling. We, and others, recently showed that Mph1 (Mps1) phosphorylates multiple conserved MELT motifs in the Spc7 (Spc105/KNL1) protein to recruit Bub1, Bub3, and Mad3 (BubR1) to kinetochores [2-4]. In budding yeast, Mps1 phosphorylation of a central non-catalytic region of Bub1 promotes its association with the Mad1-Mad2 complex, although this association has not yet been detected in other organisms [5]. Here we report that multisite binding of Bub3 to the Spc7 MELT array toggles the spindle checkpoint switch by permitting Mph1 (Mps1)-dependent interaction of Bub1 with Mad1-Mad2.
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Abstract
The spindle assembly checkpoint (SAC) is a key mechanism to regulate the timing of mitosis and ensure that chromosomes are correctly segregated to daughter cells. The recruitment of the Mad1 and Mad2 proteins to the kinetochore is normally necessary for SAC activation. This recruitment is coordinated by the SAC kinase Mps1, which phosphorylates residues at the kinetochore to facilitate binding of Bub1, Bub3, Mad1, and Mad2. There is evidence that the essential function of Mps1 is to direct recruitment of Mad1/2. To test this model, we have systematically recruited Mad1, Mad2, and Mps1 to most proteins in the yeast kinetochore, and find that, while Mps1 is sufficient for checkpoint activation, recruitment of either Mad1 or Mad2 is not. These data indicate an important role for Mps1 phosphorylation in SAC activation, beyond the direct recruitment of Mad1 and Mad2.
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48
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Abstract
The spindle assembly checkpoint is a safeguard mechanism that coordinates cell-cycle progression during mitosis with the state of chromosome attachment to the mitotic spindle. The checkpoint prevents mitotic cells from exiting mitosis in the presence of unattached or improperly attached chromosomes, thus avoiding whole-chromosome gains or losses and their detrimental effects on cell physiology. Here, I review a considerable body of recent progress in the elucidation of the molecular mechanisms underlying checkpoint signaling, and identify a number of unresolved questions.
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Affiliation(s)
- Andrea Musacchio
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany; Centre for Medical Biotechnology, Faculty of Biology, University Duisburg-Essen, Essen, Germany.
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Nuñez I, Rodriguez Pino M, Wiley DJ, Das ME, Chen C, Goshima T, Kume K, Hirata D, Toda T, Verde F. Spatial control of translation repression and polarized growth by conserved NDR kinase Orb6 and RNA-binding protein Sts5. eLife 2016; 5. [PMID: 27474797 PMCID: PMC5011436 DOI: 10.7554/elife.14216] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 07/28/2016] [Indexed: 12/18/2022] Open
Abstract
RNA-binding proteins contribute to the formation of ribonucleoprotein (RNP) granules by phase transition, but regulatory mechanisms are not fully understood. Conserved fission yeast NDR (Nuclear Dbf2-Related) kinase Orb6 governs cell morphogenesis in part by spatially controlling Cdc42 GTPase. Here we describe a novel, independent function for Orb6 kinase in negatively regulating the recruitment of RNA-binding protein Sts5 into RNPs to promote polarized cell growth. We find that Orb6 kinase inhibits Sts5 recruitment into granules, its association with processing (P) bodies, and degradation of Sts5-bound mRNAs by promoting Sts5 interaction with 14-3-3 protein Rad24. Many Sts5-bound mRNAs encode essential factors for polarized cell growth, and Orb6 kinase spatially and temporally controls the extent of Sts5 granule formation. Disruption of this control system affects cell morphology and alters the pattern of polarized cell growth, revealing a role for Orb6 kinase in the spatial control of translational repression that enables normal cell morphogenesis.
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Affiliation(s)
- Illyce Nuñez
- Molecular and Cellular Pharmacology, University of Miami School of Medicine, Miami, United States
| | - Marbelys Rodriguez Pino
- Molecular and Cellular Pharmacology, University of Miami School of Medicine, Miami, United States
| | - David J Wiley
- Molecular and Cellular Pharmacology, University of Miami School of Medicine, Miami, United States
| | - Maitreyi E Das
- Department of Biochemistry and Cellular and Molecular Biology, The University of Tennessee, Knoxville, United States
| | - Chuan Chen
- Molecular and Cellular Pharmacology, University of Miami School of Medicine, Miami, United States
| | - Tetsuya Goshima
- National Research Institute of Brewing, Higashi-Hiroshima, Japan
| | - Kazunori Kume
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Japan
| | - Dai Hirata
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Japan
| | - Takashi Toda
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Japan.,The Francis Crick Institute, Lincoln's Inn Fields Laboratory, London, United Kingdom
| | - Fulvia Verde
- Molecular and Cellular Pharmacology, University of Miami School of Medicine, Miami, United States.,Marine Biological Laboratory, Woods Hole, United States
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Chromosomal instability: A common feature and a therapeutic target of cancer. Biochim Biophys Acta Rev Cancer 2016; 1866:64-75. [PMID: 27345585 DOI: 10.1016/j.bbcan.2016.06.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Revised: 06/16/2016] [Accepted: 06/17/2016] [Indexed: 01/31/2023]
Abstract
Most cancer cells are aneuploid, containing abnormal numbers of chromosomes, mainly caused by elevated levels of chromosome missegregation, known as chromosomal instability (CIN). These well-recognized, but poorly understood, features of cancers have recently been studied extensively, unraveling causal relationships between CIN and cancer. Here we review recent findings regarding how CIN and aneuploidy occur, how they affect cellular functions, how cells respond to them, and their relevance to diseases, especially cancer. Aneuploid cells are under various kinds of stresses that result in reduced cellular fitness. Nevertheless, genetic heterogeneity derived from CIN allows the selection of cells better adapted to their environment, which supposedly facilitates generation and progression of cancer. We also discuss how we can exploit the properties of cancer cells exhibiting CIN for effective cancer therapy.
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