1
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Chen JJ, Moy C, Pagé V, Monnin C, El-Hajj ZW, Avizonis DZ, Reyes-Lamothe R, Tanny JC. The Rtf1/Prf1-dependent histone modification axis counteracts multi-drug resistance in fission yeast. Life Sci Alliance 2024; 7:e202302494. [PMID: 38514187 PMCID: PMC10958104 DOI: 10.26508/lsa.202302494] [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: 11/26/2023] [Revised: 03/05/2024] [Accepted: 03/06/2024] [Indexed: 03/23/2024] Open
Abstract
RNA polymerase II transcription elongation directs an intricate pattern of histone modifications. This pattern includes a regulatory cascade initiated by the elongation factor Rtf1, leading to monoubiquitylation of histone H2B, and subsequent methylation of histone H3 on lysine 4. Previous studies have defined the molecular basis for these regulatory relationships, but it remains unclear how they regulate gene expression. To address this question, we investigated a drug resistance phenotype that characterizes defects in this axis in the model eukaryote Schizosaccharomyces pombe (fission yeast). The mutations caused resistance to the ribonucleotide reductase inhibitor hydroxyurea (HU) that correlated with a reduced effect of HU on dNTP pools, reduced requirement for the S-phase checkpoint, and blunting of the transcriptional response to HU treatment. Mutations in the C-terminal repeat domain of the RNA polymerase II large subunit Rpb1 led to similar phenotypes. Moreover, all the HU-resistant mutants also exhibited resistance to several azole-class antifungal agents. Our results suggest a novel, shared gene regulatory function of the Rtf1-H2Bub1-H3K4me axis and the Rpb1 C-terminal repeat domain in controlling fungal drug tolerance.
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Affiliation(s)
- Jennifer J Chen
- https://ror.org/01pxwe438 Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | - Calvin Moy
- https://ror.org/01pxwe438 Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | - Viviane Pagé
- https://ror.org/01pxwe438 Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | - Cian Monnin
- https://ror.org/01pxwe438 Metabolomics Innovation Resource, Goodman Cancer Institute, McGill University, Montreal, Canada
| | - Ziad W El-Hajj
- https://ror.org/01pxwe438 Department of Biology, McGill University, Montreal, Canada
| | - Daina Z Avizonis
- https://ror.org/01pxwe438 Metabolomics Innovation Resource, Goodman Cancer Institute, McGill University, Montreal, Canada
| | - Rodrigo Reyes-Lamothe
- https://ror.org/01pxwe438 Department of Biology, McGill University, Montreal, Canada
| | - Jason C Tanny
- https://ror.org/01pxwe438 Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
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2
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RNA:DNA hybrids from Okazaki fragments contribute to establish the Ku-mediated barrier to replication-fork degradation. Mol Cell 2023; 83:1061-1074.e6. [PMID: 36868227 DOI: 10.1016/j.molcel.2023.02.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 12/09/2022] [Accepted: 02/04/2023] [Indexed: 03/05/2023]
Abstract
Nonhomologous end-joining (NHEJ) factors act in replication-fork protection, restart, and repair. Here, we identified a mechanism related to RNA:DNA hybrids to establish the NHEJ factor Ku-mediated barrier to nascent strand degradation in fission yeast. RNase H activities promote nascent strand degradation and replication restart, with a prominent role of RNase H2 in processing RNA:DNA hybrids to overcome the Ku barrier to nascent strand degradation. RNase H2 cooperates with the MRN-Ctp1 axis to sustain cell resistance to replication stress in a Ku-dependent manner. Mechanistically, the need of RNaseH2 in nascent strand degradation requires the primase activity that allows establishing the Ku barrier to Exo1, whereas impairing Okazaki fragment maturation reinforces the Ku barrier. Finally, replication stress induces Ku foci in a primase-dependent manner and favors Ku binding to RNA:DNA hybrids. We propose a function for the RNA:DNA hybrid originating from Okazaki fragments in controlling the Ku barrier specifying nuclease requirement to engage fork resection.
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3
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Rodriguez-Lopez M, Anver S, Cotobal C, Kamrad S, Malecki M, Correia-Melo C, Hoti M, Townsend S, Marguerat S, Pong SK, Wu MY, Montemayor L, Howell M, Ralser M, Bähler J. Functional profiling of long intergenic non-coding RNAs in fission yeast. eLife 2022; 11:e76000. [PMID: 34984977 PMCID: PMC8730722 DOI: 10.7554/elife.76000] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 12/02/2021] [Indexed: 12/19/2022] Open
Abstract
Eukaryotic genomes express numerous long intergenic non-coding RNAs (lincRNAs) that do not overlap any coding genes. Some lincRNAs function in various aspects of gene regulation, but it is not clear in general to what extent lincRNAs contribute to the information flow from genotype to phenotype. To explore this question, we systematically analysed cellular roles of lincRNAs in Schizosaccharomyces pombe. Using seamless CRISPR/Cas9-based genome editing, we deleted 141 lincRNA genes to broadly phenotype these mutants, together with 238 diverse coding-gene mutants for functional context. We applied high-throughput colony-based assays to determine mutant growth and viability in benign conditions and in response to 145 different nutrient, drug, and stress conditions. These analyses uncovered phenotypes for 47.5% of the lincRNAs and 96% of the protein-coding genes. For 110 lincRNA mutants, we also performed high-throughput microscopy and flow cytometry assays, linking 37% of these lincRNAs with cell-size and/or cell-cycle control. With all assays combined, we detected phenotypes for 84 (59.6%) of all lincRNA deletion mutants tested. For complementary functional inference, we analysed colony growth of strains ectopically overexpressing 113 lincRNA genes under 47 different conditions. Of these overexpression strains, 102 (90.3%) showed altered growth under certain conditions. Clustering analyses provided further functional clues and relationships for some of the lincRNAs. These rich phenomics datasets associate lincRNA mutants with hundreds of phenotypes, indicating that most of the lincRNAs analysed exert cellular functions in specific environmental or physiological contexts. This study provides groundwork to further dissect the roles of these lincRNAs in the relevant conditions.
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Affiliation(s)
- Maria Rodriguez-Lopez
- University College London, Institute of Healthy Ageing and Department of Genetics, Evolution & EnvironmentLondonUnited Kingdom
| | - Shajahan Anver
- University College London, Institute of Healthy Ageing and Department of Genetics, Evolution & EnvironmentLondonUnited Kingdom
| | - Cristina Cotobal
- University College London, Institute of Healthy Ageing and Department of Genetics, Evolution & EnvironmentLondonUnited Kingdom
| | - Stephan Kamrad
- University College London, Institute of Healthy Ageing and Department of Genetics, Evolution & EnvironmentLondonUnited Kingdom
- The Francis Crick Institute, Molecular Biology of Metabolism LaboratoryLondonUnited Kingdom
- Charité Universitätsmedizin Berlin, Institute of BiochemistryBerlinGermany
| | - Michal Malecki
- University College London, Institute of Healthy Ageing and Department of Genetics, Evolution & EnvironmentLondonUnited Kingdom
| | - Clara Correia-Melo
- The Francis Crick Institute, Molecular Biology of Metabolism LaboratoryLondonUnited Kingdom
| | - Mimoza Hoti
- University College London, Institute of Healthy Ageing and Department of Genetics, Evolution & EnvironmentLondonUnited Kingdom
| | - StJohn Townsend
- University College London, Institute of Healthy Ageing and Department of Genetics, Evolution & EnvironmentLondonUnited Kingdom
- The Francis Crick Institute, Molecular Biology of Metabolism LaboratoryLondonUnited Kingdom
| | - Samuel Marguerat
- University College London, Institute of Healthy Ageing and Department of Genetics, Evolution & EnvironmentLondonUnited Kingdom
| | - Sheng Kai Pong
- University College London, Institute of Healthy Ageing and Department of Genetics, Evolution & EnvironmentLondonUnited Kingdom
| | - Mary Y Wu
- The Francis Crick Institute, High Throughput ScreeningLondonUnited Kingdom
| | - Luis Montemayor
- University College London, Institute of Healthy Ageing and Department of Genetics, Evolution & EnvironmentLondonUnited Kingdom
| | - Michael Howell
- The Francis Crick Institute, High Throughput ScreeningLondonUnited Kingdom
| | - Markus Ralser
- The Francis Crick Institute, Molecular Biology of Metabolism LaboratoryLondonUnited Kingdom
- Charité Universitätsmedizin Berlin, Institute of BiochemistryBerlinGermany
| | - Jürg Bähler
- University College London, Institute of Healthy Ageing and Department of Genetics, Evolution & EnvironmentLondonUnited Kingdom
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4
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Kianfard Z, Cheung K, Rappaport D, Magalage SP, Sabatinos SA. Detecting Cell Cycle Stage and Progression in Fission Yeast, Schizosaccharomyces pombe. Methods Mol Biol 2022; 2579:235-246. [PMID: 36045211 DOI: 10.1007/978-1-0716-2736-5_18] [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: 06/15/2023]
Abstract
We have previously described methods to synchronize cultures of fission yeast, Schizosaccharomyces pombe. In this chapter, we provide methods to detect cell cycle stage in cells and populations of S. pombe. These protocols used fixed samples. First, we describe sample preparation for flow cytometry of bulk DNA content. This technique allows users to monitor progression of DNA replication and detect any perturbation during the synthesis (S) phase of the cell cycle. Second, we describe methods to stain nuclei and septa of fixed yeast cells, and monitor proportions of cell cycle stages within cultures. Together, these methods provide the ability to compare cell cycle progression or delay between cultures, making use of the powerful molecular genetics tool that is S. pombe.
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Affiliation(s)
- Zohreh Kianfard
- Molecular Science Program, Yeates School of Graduate Studies, Toronto Metropolitan University (formerly Ryerson University), Toronto, ON, Canada
| | - Kyle Cheung
- Molecular Science Program, Yeates School of Graduate Studies, Toronto Metropolitan University (formerly Ryerson University), Toronto, ON, Canada
| | - Daniel Rappaport
- Molecular Science Program, Yeates School of Graduate Studies, Toronto Metropolitan University (formerly Ryerson University), Toronto, ON, Canada
| | - Sirasie P Magalage
- Molecular Science Program, Yeates School of Graduate Studies, Toronto Metropolitan University (formerly Ryerson University), Toronto, ON, Canada
| | - Sarah A Sabatinos
- Molecular Science Program, Yeates School of Graduate Studies, Toronto Metropolitan University (formerly Ryerson University), Toronto, ON, Canada.
- Department of Chemistry and Biology, Toronto Metropolitan University (formerly Ryerson University), Toronto, ON, Canada.
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5
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The histone chaperone FACT facilitates heterochromatin spreading by regulating histone turnover and H3K9 methylation states. Cell Rep 2021; 37:109944. [PMID: 34731638 PMCID: PMC8608617 DOI: 10.1016/j.celrep.2021.109944] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 09/14/2021] [Accepted: 10/13/2021] [Indexed: 12/13/2022] Open
Abstract
Heterochromatin formation requires three distinct steps: nucleation, self-propagation (spreading) along the chromosome, and faithful maintenance after each replication cycle. Impeding any of those steps induces heterochromatin defects and improper gene expression. The essential histone chaperone FACT (facilitates chromatin transcription) has been implicated in heterochromatin silencing, but the mechanisms by which FACT engages in this process remain opaque. Here, we pinpoint its function to the heterochromatin spreading process in fission yeast. FACT impairment reduces nucleation-distal H3K9me3 and HP1/Swi6 accumulation at subtelomeres and derepresses genes in the vicinity of heterochromatin boundaries. FACT promotes spreading by repressing heterochromatic histone turnover, which is crucial for the H3K9me2 to me3 transition that enables spreading. FACT mutant spreading defects are suppressed by removal of the H3K9 methylation antagonist Epe1. Together, our study identifies FACT as a histone chaperone that promotes heterochromatin spreading and lends support to the model that regulated histone turnover controls the propagation of repressive methylation marks. Heterochromatin establishment requires distinct nucleation and spreading steps. Murawska et al. show that the conserved and essential histone chaperone FACT facilitates the heterochromatin spreading process by maintaining low heterochromatic histone turnover, which enables a productive H3K9 trimethylation step by the methyltransferase Clr4 in fission yeast.
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6
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High-Throughput Flow Cytometry Combined with Genetic Analysis Brings New Insights into the Understanding of Chromatin Regulation of Cellular Quiescence. Int J Mol Sci 2020; 21:ijms21239022. [PMID: 33260998 PMCID: PMC7729564 DOI: 10.3390/ijms21239022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 11/19/2020] [Accepted: 11/23/2020] [Indexed: 11/21/2022] Open
Abstract
Cellular quiescence is a reversible differentiation state when cells are changing the gene expression program to reduce metabolic functions and adapt to a new cellular environment. When fission yeast cells are deprived of nitrogen in the absence of any mating partner, cells can reversibly arrest in a differentiated G0-like cellular state, called quiescence. This change is accompanied by a marked alteration of nuclear organization and a global reduction of transcription. Using high-throughput flow cytometry combined with genetic analysis, we describe the results of a comprehensive screen for genes encoding chromatin components and regulators that are required for the entry and the maintenance of cellular quiescence. We show that the histone acetylase and deacetylase complexes, SAGA and Rpd3, have key roles both for G0 entry and survival during quiescence. We reveal a novel function for the Ino80 nucleosome remodeling complex in cellular quiescence. Finally, we demonstrate that components of the MRN complex, Rad3, the nonhomologous end-joining, and nucleotide excision DNA repair pathways are essential for viability in G0.
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7
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Bartle L, Mitchell JG, Paterson JS. Evaluating the Cytometric Detection and Enumeration of the Wine Bacterium, Oenococcus oeni. Cytometry A 2020; 99:399-406. [PMID: 33140503 DOI: 10.1002/cyto.a.24258] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 10/28/2020] [Accepted: 10/29/2020] [Indexed: 12/29/2022]
Abstract
Flow cytometry is a high-throughput tool for determining microbial abundance in a range of medical, environmental, and food-related samples. For wine, determining the abundance of Saccharomyces cerevisiae is well-defined and reliable. However, for the most common wine bacterium, Oenococcus oeni, using flow cytometry to determine cell concentration poses some challenges. O. oeni most often occurs in doublets or chains of varying lengths that can be greater than seven cells. This wine bacterium is also small, at 0.2-0.6 μm and may exhibit a range of morphologies including binary fission and aggregated complexes. This work demonstrates a straightforward approach to determining the suitability of flow cytometry for the chain-forming bacteria, O. oeni, and considerations when using flow cytometry for the enumeration of small microorganisms (<0.5 μm). © 2020 International Society for Advancement of Cytometry.
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Affiliation(s)
- Louise Bartle
- Department of Wine and Food Science, The University of Adelaide, Urrbrae, Australia.,Department of Microbiology and Infectious Diseases, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - James G Mitchell
- Flinders University, College of Science and Engineering, Adelaide, Australia
| | - James S Paterson
- Flinders University, College of Science and Engineering, Adelaide, Australia
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8
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Špačková J, Oliveira D, Puškár M, Ďurovcová I, Gaplovská-Kyselá K, Oliveira R, Ševčovičová A. Endocrine-Independent Cytotoxicity of Bisphenol A Is Mediated by Increased Levels of Reactive Oxygen Species and Affects Cell Cycle Progression. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020; 68:869-875. [PMID: 31880940 DOI: 10.1021/acs.jafc.9b06853] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Bisphenol A (BPA) is used for the production of plastics and epoxy resins, which are part of packaging materials for food and beverages, and can migrate into food and the environment, thus exposing human beings to its effects. Exposure to BPA has been associated with oxidative stress, cell cycle changes, and genotoxicity, and is mediated by its known endocrine-disrupting activity. Possible BPA cytotoxicity without mediation by estrogen receptors has been reported in the literature. Here, we show the toxic effects of BPA by live-cell imaging on the fission yeast Schizosaccharomyces pombe, an experimental model lacking estrogen receptors, which were in line with data from flow cytometry on intracellular oxidation (76.4 ± 14.4 and 19.4 ± 16.1% of fluorescent cells for BPA treatment and control, respectively; p < 0.05) as well as delay in cell cycle progression (after 90 min of experiment, 48.4 ± 4.30 and 64.6 ± 5.46% of cells with a 4C DNA content for BPA treatment and control, respectively; p < 0.05) upon exposure to BPA. These results strongly support the possibilities that BPA-induced cell cycle changes can be independent of estrogen receptors and that live-cell imaging is a powerful tool for genotoxic analysis.
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Affiliation(s)
- Jana Špačková
- Faculty of Natural Sciences, Department of Genetics , Comenius University , Ilkovičova 6, Mlynská dolina , 842 15 Bratislava , Slovakia
| | - Daniela Oliveira
- Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB), Department of Biology , University of Minho , Campus de Gualtar , 4710-057 Braga , Portugal
| | - Marek Puškár
- Faculty of Natural Sciences, Department of Genetics , Comenius University , Ilkovičova 6, Mlynská dolina , 842 15 Bratislava , Slovakia
| | - Ivana Ďurovcová
- Faculty of Natural Sciences, Department of Genetics , Comenius University , Ilkovičova 6, Mlynská dolina , 842 15 Bratislava , Slovakia
| | - Katarína Gaplovská-Kyselá
- Faculty of Natural Sciences, Department of Genetics , Comenius University , Ilkovičova 6, Mlynská dolina , 842 15 Bratislava , Slovakia
| | - Rui Oliveira
- Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB), Department of Biology , University of Minho , Campus de Gualtar , 4710-057 Braga , Portugal
- Centre of Biological Engineering, Department of Biology , University of Minho , Campus de Gualtar , 4710-057 Braga , Portugal
| | - Andrea Ševčovičová
- Faculty of Natural Sciences, Department of Genetics , Comenius University , Ilkovičova 6, Mlynská dolina , 842 15 Bratislava , Slovakia
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9
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Birot A, Tormos-Pérez M, Vaur S, Feytout A, Jaegy J, Alonso Gil D, Vazquez S, Ekwall K, Javerzat JP. The CDK Pef1 and protein phosphatase 4 oppose each other for regulating cohesin binding to fission yeast chromosomes. eLife 2020; 9:e50556. [PMID: 31895039 PMCID: PMC6954021 DOI: 10.7554/elife.50556] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 01/02/2020] [Indexed: 12/19/2022] Open
Abstract
Cohesin has essential roles in chromosome structure, segregation and repair. Cohesin binding to chromosomes is catalyzed by the cohesin loader, Mis4 in fission yeast. How cells fine tune cohesin deposition is largely unknown. Here, we provide evidence that Mis4 activity is regulated by phosphorylation of its cohesin substrate. A genetic screen for negative regulators of Mis4 yielded a CDK called Pef1, whose closest human homologue is CDK5. Inhibition of Pef1 kinase activity rescued cohesin loader deficiencies. In an otherwise wild-type background, Pef1 ablation stimulated cohesin binding to its regular sites along chromosomes while ablating Protein Phosphatase 4 had the opposite effect. Pef1 and PP4 control the phosphorylation state of the cohesin kleisin Rad21. The CDK phosphorylates Rad21 on Threonine 262. Pef1 ablation, non-phosphorylatable Rad21-T262 or mutations within a Rad21 binding domain of Mis4 alleviated the effect of PP4 deficiency. Such a CDK/PP4-based regulation of cohesin loader activity could provide an efficient mechanism for translating cellular cues into a fast and accurate cohesin response.
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Affiliation(s)
- Adrien Birot
- Institut de Biochimie et Génétique Cellulaires, UMR 5095 CNRS - Université de BordeauxBordeauxFrance
| | - Marta Tormos-Pérez
- Institut de Biochimie et Génétique Cellulaires, UMR 5095 CNRS - Université de BordeauxBordeauxFrance
| | - Sabine Vaur
- Institut de Biochimie et Génétique Cellulaires, UMR 5095 CNRS - Université de BordeauxBordeauxFrance
| | - Amélie Feytout
- Institut de Biochimie et Génétique Cellulaires, UMR 5095 CNRS - Université de BordeauxBordeauxFrance
| | - Julien Jaegy
- Institut de Biochimie et Génétique Cellulaires, UMR 5095 CNRS - Université de BordeauxBordeauxFrance
| | - Dácil Alonso Gil
- Institut de Biochimie et Génétique Cellulaires, UMR 5095 CNRS - Université de BordeauxBordeauxFrance
| | - Stéphanie Vazquez
- Institut de Biochimie et Génétique Cellulaires, UMR 5095 CNRS - Université de BordeauxBordeauxFrance
| | - Karl Ekwall
- Department of Biosciences and NutritionKarolinska InstitutetHuddingeSweden
| | - Jean-Paul Javerzat
- Institut de Biochimie et Génétique Cellulaires, UMR 5095 CNRS - Université de BordeauxBordeauxFrance
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10
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Pagé V, Chen JJ, Durand-Dubief M, Grabowski D, Oya E, Sansô M, Martin RD, Hébert TE, Fisher RP, Ekwall K, Tanny JC. Histone H2B Ubiquitylation Regulates Histone Gene Expression by Suppressing Antisense Transcription in Fission Yeast. Genetics 2019; 213:161-172. [PMID: 31345994 PMCID: PMC6727805 DOI: 10.1534/genetics.119.302499] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 07/23/2019] [Indexed: 02/08/2023] Open
Abstract
Histone H2B monoubiquitylation (H2Bub1) is tightly linked to RNA polymerase II transcription elongation, and is also directly implicated in DNA replication and repair. Loss of H2Bub1 is associated with defects in cell cycle progression, but how these are related to its various functions, and the underlying mechanisms involved, is not understood. Here we describe a role for H2Bub1 in the regulation of replication-dependent histone genes in the fission yeast Schizosaccharomyces pombe H2Bub1 activates histone genes indirectly by suppressing antisense transcription of ams2+ -a gene encoding a GATA-type transcription factor that activates histone genes and is required for assembly of centromeric chromatin. Mutants lacking the ubiquitylation site in H2B or the H2B-specific E3 ubiquitin ligase Brl2 had elevated levels of ams2+ antisense transcripts and reduced Ams2 protein levels. These defects were reversed upon inhibition of Cdk9-an ortholog of the kinase component of positive transcription elongation factor b (P-TEFb)-indicating that they likely resulted from aberrant transcription elongation. Reduced Cdk9 activity also partially rescued chromosome segregation phenotypes of H2Bub1 mutants. In a genome-wide analysis, loss of H2Bub1 led to increased antisense transcripts at over 500 protein-coding genes in H2Bub1 mutants; for a subset of these, including several genes involved in chromosome segregation and chromatin assembly, antisense derepression was Cdk9-dependent. Our results highlight antisense suppression as a key feature of cell cycle-dependent gene regulation by H2Bub1, and suggest that aberrant transcription elongation may underlie the effects of H2Bub1 loss on cell cycle progression.
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Affiliation(s)
- Viviane Pagé
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec H3G 1Y6, Canada
| | - Jennifer J Chen
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec H3G 1Y6, Canada
| | - Mickael Durand-Dubief
- Department of Biosciences and Nutrition, Karolinska Institute, Stockholm 17177, Sweden
| | - David Grabowski
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec H3G 1Y6, Canada
| | - Eriko Oya
- Department of Biosciences and Nutrition, Karolinska Institute, Stockholm 17177, Sweden
| | - Miriam Sansô
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, Mount Sinai School of Medicine, New York, New York 10029
| | - Ryan D Martin
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec H3G 1Y6, Canada
| | - Terence E Hébert
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec H3G 1Y6, Canada
| | - Robert P Fisher
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, Mount Sinai School of Medicine, New York, New York 10029
| | - Karl Ekwall
- Department of Biosciences and Nutrition, Karolinska Institute, Stockholm 17177, Sweden
| | - Jason C Tanny
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec H3G 1Y6, Canada
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11
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Andreadis C, Hulme L, Wensley K, Liu JL. The TOR pathway modulates cytoophidium formation in Schizosaccharomyces pombe. J Biol Chem 2019; 294:14686-14703. [PMID: 31431504 PMCID: PMC6779450 DOI: 10.1074/jbc.ra119.009913] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Revised: 08/09/2019] [Indexed: 12/30/2022] Open
Abstract
CTP synthase (CTPS) has been demonstrated to form evolutionarily-conserved filamentous structures termed cytoophidia whose exact cellular functions remain unclear, but they may play a role in intracellular compartmentalization. We have previously shown that the mammalian target of rapamycin complex 1 (mTORC1)-S6K1 pathway mediates cytoophidium assembly in mammalian cells. Here, using the fission yeast Schizosaccharomyces pombe as a model of a unicellular eukaryote, we demonstrate that the target of rapamycin (TOR)-signaling pathway regulates cytoophidium formation (from the S. pombe CTPS ortholog Cts1) also in S. pombe Conducting a systematic analysis of all viable single TOR subunit-knockout mutants and of several major downstream effector proteins, we found that Cts1 cytoophidia are significantly shortened and often dissociate when TOR is defective. We also found that the activities of the downstream effector kinases of the TORC1 pathway, Sck1, Sck2, and Psk1 S6, as well as of the S6K/AGC kinase Gad8, the major downstream effector kinase of the TORC2 pathway, are necessary for proper cytoophidium filament formation. Interestingly, we observed that the Crf1 transcriptional corepressor for ribosomal genes is a strong effector of Cts1 filamentation. Our findings connect TOR signaling, a major pathway required for cell growth, with the compartmentalization of the essential nucleotide synthesis enzyme CTPS, and we uncover differences in the regulation of its filamentation among higher multicellular and unicellular eukaryotic systems.
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Affiliation(s)
- Christos Andreadis
- School of Life Sciences and Technology, ShanghaiTech University, 201210 Shanghai, China
| | - Lydia Hulme
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
| | - Katherine Wensley
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
| | - Ji-Long Liu
- School of Life Sciences and Technology, ShanghaiTech University, 201210 Shanghai, China .,MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
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12
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Ghosh S, Pal A, Ray M. Methylglyoxal in combination with 5-Fluorouracil elicits improved chemosensitivity in breast cancer through apoptosis and cell cycle inhibition. Biomed Pharmacother 2019; 114:108855. [DOI: 10.1016/j.biopha.2019.108855] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 03/27/2019] [Accepted: 04/02/2019] [Indexed: 10/27/2022] Open
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13
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Butenolides from a marine-derived fungus Aspergillus terreus with antitumor activities against pancreatic ductal adenocarcinoma cells. Bioorg Med Chem 2018; 26:5903-5910. [PMID: 30392953 DOI: 10.1016/j.bmc.2018.10.040] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 10/24/2018] [Accepted: 10/29/2018] [Indexed: 12/13/2022]
Abstract
Chemical study on the extract of a marine-derived fungus Aspergillus terreus yielded twelve butenolide derivatives, including three new compounds, namely asperlides A-C (1-3) and nine known butenolides (4-12). The structures of 1-3 were confirmed by comprehensive spectroscopic analysis, including HRESIMS, NMR spectroscopy, and calculated electronic circular dichroism (ECD). The cytotoxicity of the compounds was evaluated using PANC-1, HCC1806, HepG2, BEAS-2B and HT-29 cancer cells. The results showed that (+)-3',3'-di-(dimethylallyl)-butyrolactone II (4) and versicolactone B (6) exhibited the most potent cytotoxin of PANC-1 cell line, with the IC50 values of 5.3 and 9.4 μM, respectively. Morphological features of apoptosis were observed in 4 and 6-treated PANC-1 cells, including apoptotic body formation, membrane blebbing, cell shrinkage and nuclear condensation. Cell cycle analysis with propidium iodide staining exhibited that 4 inhibits proliferation of PANC-1 cells via the induction of G2/M and S phase arrest, while 6 could retard the PANC-1 cells via the induction of S phase arrest. Flow cytometric analysis suggested that treatment with 4 and 6 significantly induced PANC-1 cells apoptosis. These findings indicated that 4 and 6 might serve as a starting point for the development of an anticancer drug for the treatment of pancreatic ductal adenocarcinoma.
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14
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Stonyte V, Boye E, Grallert B. Regulation of global translation during the cell cycle. J Cell Sci 2018; 131:jcs.220327. [PMID: 30072440 DOI: 10.1242/jcs.220327] [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: 05/14/2018] [Accepted: 07/20/2018] [Indexed: 01/10/2023] Open
Abstract
It is generally accepted that global translation varies during the cell cycle and is low during mitosis. However, addressing this issue is challenging because it involves cell synchronization, which evokes stress responses that, in turn, affect translation rates. Here, we have used two approaches to measure global translation rates in different cell-cycle phases. First, synchrony in different cell-cycle phases was obtained involving the same stress, by using temperature-sensitive mutants. Second, translation and DNA content were measured by flow cytometry in exponentially growing, single cells. We found no major variation in global translation rates through the cell cycle in either fission yeast or mammalian cells. We also measured phosphorylation of eukaryotic initiation factor-2α, an event that is thought to downregulate global translation in mitosis. In contrast with the prevailing view, eIF2α phosphorylation correlated poorly with downregulation of global translation and ectopically induced eIF2α phosphorylation inhibited global translation only at high levels.
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Affiliation(s)
- Vilte Stonyte
- Department of Radiation Biology, Institute for Cancer Research, Montebello, 0379 Oslo University Hospital, Oslo, Norway
| | - Erik Boye
- Department of Radiation Biology, Institute for Cancer Research, Montebello, 0379 Oslo University Hospital, Oslo, Norway
| | - Beáta Grallert
- Department of Radiation Biology, Institute for Cancer Research, Montebello, 0379 Oslo University Hospital, Oslo, Norway
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15
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Greenstein RA, Jones SK, Spivey EC, Rybarski JR, Finkelstein IJ, Al-Sady B. Noncoding RNA-nucleated heterochromatin spreading is intrinsically labile and requires accessory elements for epigenetic stability. eLife 2018; 7:32948. [PMID: 30020075 PMCID: PMC6070336 DOI: 10.7554/elife.32948] [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: 10/19/2017] [Accepted: 07/17/2018] [Indexed: 12/22/2022] Open
Abstract
The heterochromatin spreading reaction is a central contributor to the formation of gene-repressive structures, which are re-established with high positional precision, or fidelity, following replication. How the spreading reaction contributes to this fidelity is not clear. To resolve the origins of stable inheritance of repression, we probed the intrinsic character of spreading events in fission yeast using a system that quantitatively describes the spreading reaction in live single cells. We show that spreading triggered by noncoding RNA-nucleated elements is stochastic, multimodal, and fluctuates dynamically across time. This lack of stability correlates with high histone turnover. At the mating type locus, this unstable behavior is restrained by an accessory cis-acting element REIII, which represses histone turnover. Further, REIII safeguards epigenetic memory against environmental perturbations. Our results suggest that the most prevalent type of spreading, driven by noncoding RNA-nucleators, is epigenetically unstable and requires collaboration with accessory elements to achieve high fidelity.
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Affiliation(s)
- R A Greenstein
- Department of Microbiology & Immunology, George Williams Hooper Foundation, University of California San Francisco, San Francisco, United States.,TETRAD graduate program, University of California San Francisco, San Francisco, United States
| | - Stephen K Jones
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, United States
| | - Eric C Spivey
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, United States
| | - James R Rybarski
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, United States
| | - Ilya J Finkelstein
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, United States.,Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, United States
| | - Bassem Al-Sady
- Department of Microbiology & Immunology, George Williams Hooper Foundation, University of California San Francisco, San Francisco, United States
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16
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Bøe CA, Håland TW, Boye E, Syljuåsen RG, Grallert B. A novel role for ATR/Rad3 in G1 phase. Sci Rep 2018; 8:6880. [PMID: 29720710 PMCID: PMC5931961 DOI: 10.1038/s41598-018-25238-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 04/12/2018] [Indexed: 12/29/2022] Open
Abstract
Checkpoint kinases are important in cellular surveillance pathways that help cells to cope with DNA damage and protect their genomes. In cycling cells, DNA replication is one of the most sensitive processes and therefore all organisms carefully regulate replication initiation and progression. The checkpoint kinase ATR plays important roles both in response to DNA damage and replication stress, and ATR inhibitors are currently in clinical trials for cancer treatment. Therefore, it is important to understand the roles of ATR in detail. Here we show that the fission yeast homologue Rad3 and the human ATR regulate events also in G1 phase in an unperturbed cell cycle. Rad3Δ mutants or human cells exposed to ATR inhibitor in G1 enter S phase prematurely, which results in increased DNA damage. Furthermore, ATR inhibition in a single G1 reduces clonogenic survival, demonstrating that long-term effects of ATR inhibition during G1 are deleterious for the cell. Interestingly, ATR inhibition through G1 and S phase reduces survival in an additive manner, strongly arguing that different functions of ATR are targeted in the different cell-cycle phases. We propose that potential effects of ATR inhibitors in G1 should be considered when designing future treatment protocols with such inhibitors.
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Affiliation(s)
- Cathrine A Bøe
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Tine W Håland
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Erik Boye
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Randi G Syljuåsen
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Beáta Grallert
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.
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17
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Du W, Forte GM, Smith D, Petersen J. Phosphorylation of the amino-terminus of the AGC kinase Gad8 prevents its interaction with TORC2. Open Biol 2016; 6:rsob.150189. [PMID: 26935949 PMCID: PMC4821236 DOI: 10.1098/rsob.150189] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cell proliferation, metabolism, migration and survival are coordinated through the tight control of two target of rapamycin (TOR) kinase complexes: TORC1 and TORC2. Here, we show that a novel phosphorylation of fission yeast Gad8 (AGC kinase) on the evolutionarily conserved threonine 6 (Thr6) prevents the physical association between Gad8 and TORC2. Accordingly, this block to protein interactions by Gad8 Thr6 phosphorylation decreases TORC2-controlled activation of Gad8. Likewise, phosphorylation of Gad8 Thr6, possibly by PKC, prevents the association of Gad8 with TORC2 thereby increasing TORC2 activity, because it reduces Gad8-mediated feedback inhibition of TORC2. Consistently, the introduction of a Gad8 T6D mutant, that mimics phosphorylation, increased TORC2 activity. Increased PKCPck2 expression prevented Gad8–TORC2 binding and so reduced the TORC2-mediated phosphorylation of Gad8 serine 546 that activates Gad8. Interestingly, independent of the Ser546 phosphorylation status, Gad8 Thr6 phosphorylation is important for remodelling the actin cytoskeleton and survival upon potassium ion and heat stresses. In contrast, Ser546 phosphorylation is required for the control of G1 arrest, mating, cell length at division and vascular size. Finally, these findings reveal a novel mode of TORC2 activation that is essential for cell survival following stress.
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Affiliation(s)
- Wei Du
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Gabriella M Forte
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Duncan Smith
- Biological Mass Spectrometry, Cancer Research UK Manchester Institute, The Paterson Building, Wilmslow Road, Manchester M20 4BX, UK
| | - Janni Petersen
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK Flinders Centre for Innovation in Cancer, School of Medicine, Flinders University, Adelaide, South Australia 5001, Australia South Australia Health and Medical Research Institute, North Terrace, PO Box 11060, Adelaide, South Australia 5000, Australia
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18
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Boye E, Anda S, Rothe C, Stokke T, Grallert B. Analyzing Schizosaccharomyces pombe DNA Content by Flow Cytometry. Cold Spring Harb Protoc 2016; 2016:2016/6/pdb.prot091280. [PMID: 27250946 DOI: 10.1101/pdb.prot091280] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Flow cytometry can be used to measure the DNA content of individual cells. The data are usually presented as DNA histograms that can be used to examine the cells' progression through the cell cycle. Under standard growth conditions, fission yeast cells do not complete cytokinesis until after G1 phase; therefore, DNA histograms show one major peak representing cells in G1 (2×1C DNA) and G2 phase (1×2C DNA). By analysis of the duration of the fluorescence signal as well as the intensity of the DNA-related signal, it is possible to discriminate between cells in M/G1, S, and G2 This protocol describes how to prepare cells for flow cytometry and analyze them. We also describe the application of barcoding for more accurate comparison of samples.
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Affiliation(s)
- Erik Boye
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, 0310 Oslo, Norway
| | - Silje Anda
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, 0310 Oslo, Norway
| | - Christiane Rothe
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, 0310 Oslo, Norway
| | - Trond Stokke
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, 0310 Oslo, Norway
| | - Beáta Grallert
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, 0310 Oslo, Norway
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19
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Papp G, Máté G, Mike N, Gazdag Z, Pesti M. Regulation of the antioxidant system in cells of the fission yeast Schizosaccharomyces pombe after combined treatment with patulin and citrinin. Toxicon 2016; 111:100-7. [PMID: 26752674 DOI: 10.1016/j.toxicon.2015.12.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 12/10/2015] [Accepted: 12/29/2015] [Indexed: 10/25/2022]
Abstract
The effects of combined treatment with patulin (PAT) and citrinin (CTN) on Schizosaccharomyces pombe cells were investigated in acute toxicity tests. In comparison with the controls the exposure of fission yeast cells (10(7) cells ml(-1)) to PAT + CTN (250 μM each) for 1 h at a survival rate of 66.6% significantly elevated the concentration of total reactive oxygen species (ROS) via increased levels of peroxides without affecting the concentrations of superoxides or the hydroxyl radical. This treatment induced a 3.08-fold increase in the specific concentration of glutathione and elevated specific activities of catalase and glutathione S-transferase, while at the same time the activity of glutathione reductase decreased. The pattern of the ROS was the same as that induced by CTN (Máté et al., 2014), while the presence of PAT in the PAT + CTN combination treatment modified the activities of the antioxidant system (Papp et al., 2012) in comparison with the individual PAT or CTN treatment, suggesting toxin-specific regulation of glutathione and the enzymes of the antioxidant system and the possibility that the transcription factor (pap1 and atf1) -regulated processes might be influenced directly by ROS.
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Affiliation(s)
- Gábor Papp
- Department of General and Environmental Microbiology, Faculty of Sciences, University of Pécs, Pécs, Hungary; Microbial Biotechnology Research Group, János Szentágothai Research Centre, University of Pécs, Pécs, Hungary.
| | - Gábor Máté
- Department of General and Environmental Microbiology, Faculty of Sciences, University of Pécs, Pécs, Hungary
| | - Nóra Mike
- Department of General and Environmental Microbiology, Faculty of Sciences, University of Pécs, Pécs, Hungary
| | - Zoltán Gazdag
- Department of General and Environmental Microbiology, Faculty of Sciences, University of Pécs, Pécs, Hungary; Microbial Biotechnology Research Group, János Szentágothai Research Centre, University of Pécs, Pécs, Hungary
| | - Miklós Pesti
- Department of General and Environmental Microbiology, Faculty of Sciences, University of Pécs, Pécs, Hungary
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20
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Genome-Wide Estimates of Mutation Rates and Spectrum in Schizosaccharomyces pombe Indicate CpG Sites are Highly Mutagenic Despite the Absence of DNA Methylation. G3-GENES GENOMES GENETICS 2015; 6:149-60. [PMID: 26564949 PMCID: PMC4704713 DOI: 10.1534/g3.115.022129] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We accumulated mutations for 1952 generations in 79 initially identical, haploid lines of the fission yeast Schizosaccharomyces pombe, and then performed whole-genome sequencing to determine the mutation rates and spectrum. We captured 696 spontaneous mutations across the 79 mutation accumulation (MA) lines. We compared the mutation spectrum and rate to a recently published equivalent experiment on the same species, and to another model ascomycetous yeast, the budding yeast Saccharomyces cerevisiae. While the two species are approximately 600 million years diverged from each other, they share similar life histories, genome size and genomic G/C content. We found that Sc. pombe and S. cerevisiae have similar mutation rates, but Sc. pombe exhibits a stronger insertion bias. Intriguingly, we observed an increased mutation rate at cytosine nucleotides, specifically CpG nucleotides, which is also seen in S. cerevisiae. However, the absence of methylation in Sc. pombe and the pattern of mutation at these sites, primarily C → A as opposed to C → T, strongly suggest that the increased mutation rate is not caused by deamination of methylated cytosines. This result implies that the high mutability of CpG dinucleotides in other species may be caused in part by a methylation-independent mechanism. Many of our findings mirror those seen in the recent study, despite the use of different passaging conditions, indicating that MA is a reliable method for estimating mutation rates and spectra.
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21
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Knutsen JHJ, Rødland GE, Bøe CA, Håland TW, Sunnerhagen P, Grallert B, Boye E. Stress-induced inhibition of translation independently of eIF2α phosphorylation. J Cell Sci 2015; 128:4420-7. [PMID: 26493332 PMCID: PMC4712817 DOI: 10.1242/jcs.176545] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 09/28/2015] [Indexed: 01/21/2023] Open
Abstract
Exposure of fission yeast cells to ultraviolet (UV) light leads to inhibition of translation and phosphorylation of the eukaryotic initiation factor-2α (eIF2α). This phosphorylation is a common response to stress in all eukaryotes. It leads to inhibition of translation at the initiation stage and is thought to be the main reason why stressed cells dramatically reduce protein synthesis. Phosphorylation of eIF2α has been taken as a readout for downregulation of translation, but the role of eIF2α phosphorylation in the downregulation of general translation has not been much investigated. We show here that UV-induced global inhibition of translation in fission yeast cells is independent of eIF2α phosphorylation and the eIF2α kinase general control nonderepressible-2 protein (Gcn2). Also, in budding yeast and mammalian cells, the UV-induced translational depression is largely independent of GCN2 and eIF2α phosphorylation. Furthermore, exposure of fission yeast cells to oxidative stress generated by hydrogen peroxide induced an inhibition of translation that is also independent of Gcn2 and of eIF2α phosphorylation. Our findings show that stress-induced translational inhibition occurs through an unknown mechanism that is likely to be conserved through evolution. Summary: In contrast to textbook knowledge, the phosphorylation of translation initiation factor eIF2α is not required for UV-induced inhibition of protein synthesis, which we show in three different cell types.
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Affiliation(s)
| | - Gro Elise Rødland
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Cathrine Arnason Bøe
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Tine Weise Håland
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Per Sunnerhagen
- Department of Chemistry & Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Beáta Grallert
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Erik Boye
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
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22
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Převorovský M, Oravcová M, Tvarůžková J, Zach R, Folk P, Půta F, Bähler J. Fission Yeast CSL Transcription Factors: Mapping Their Target Genes and Biological Roles. PLoS One 2015; 10:e0137820. [PMID: 26366556 PMCID: PMC4569565 DOI: 10.1371/journal.pone.0137820] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 08/24/2015] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Cbf11 and Cbf12, the fission yeast CSL transcription factors, have been implicated in the regulation of cell-cycle progression, but no specific roles have been described and their target genes have been only partially mapped. METHODOLOGY/PRINCIPAL FINDINGS Using a combination of transcriptome profiling under various conditions and genome-wide analysis of CSL-DNA interactions, we identify genes regulated directly and indirectly by CSL proteins in fission yeast. We show that the expression of stress-response genes and genes that are expressed periodically during the cell cycle is deregulated upon genetic manipulation of cbf11 and/or cbf12. Accordingly, the coordination of mitosis and cytokinesis is perturbed in cells with genetically manipulated CSL protein levels, together with other specific defects in cell-cycle progression. Cbf11 activity is nutrient-dependent and Δcbf11-associated defects are mitigated by inactivation of the protein kinase A (Pka1) and stress-activated MAP kinase (Sty1p38) pathways. Furthermore, Cbf11 directly regulates a set of lipid metabolism genes and Δcbf11 cells feature a stark decrease in the number of storage lipid droplets. CONCLUSIONS/SIGNIFICANCE Our results provide a framework for a more detailed understanding of the role of CSL proteins in the regulation of cell-cycle progression in fission yeast.
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Affiliation(s)
- Martin Převorovský
- Research Department of Genetics, Evolution & Environment and UCL Cancer Institute, University College London, London, United Kingdom
- Department of Cell Biology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Martina Oravcová
- Department of Cell Biology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Jarmila Tvarůžková
- Department of Cell Biology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Róbert Zach
- Department of Cell Biology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Petr Folk
- Department of Cell Biology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - František Půta
- Department of Cell Biology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Jürg Bähler
- Research Department of Genetics, Evolution & Environment and UCL Cancer Institute, University College London, London, United Kingdom
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23
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Patterson JO, Swaffer M, Filby A. An Imaging Flow Cytometry-based approach to analyse the fission yeast cell cycle in fixed cells. Methods 2015; 82:74-84. [DOI: 10.1016/j.ymeth.2015.04.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Revised: 03/28/2015] [Accepted: 04/08/2015] [Indexed: 02/05/2023] Open
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24
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Filby A. New, clear fusion from the cellular perspective: Measuring cellular fusion in Saccharomyces cerevisiae by flow cytometry. Cytometry A 2015; 87:797-9. [PMID: 26115228 DOI: 10.1002/cyto.a.22714] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 06/10/2015] [Indexed: 11/09/2022]
Affiliation(s)
- Andrew Filby
- Flow Cytometry Core Facility, Newcastle Biomedicine, Newcastle University, Newcastle-upon-Tyne, NE1 7RU, United Kingdom
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25
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Crosby HA, Ihnat M, Miller KE. Evaluating the Toxicity of the Analgesic Glutaminase Inhibitor 6-Diazo-5-Oxo-L-Norleucine in vitro and on Rat Dermal Skin Fibroblasts. ACTA ACUST UNITED AC 2015; 1. [PMID: 29750203 DOI: 10.15406/mojt.2015.01.00005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
6-diazo-5-oxo-l-norleucine (DON) is a glutamine antagonist produced naturally by Streptomyces. It inhibits several glutamine-dependent enzyme pathways. Of particular note is its inhibitory effect on the mitochondrial enzyme, glutaminase (GLS), the primary producer of neuronal glutamate. Glutamate is an excitatory neurotransmitter released by primary sensory peripheral nerve terminals and spinal synaptic terminals during pain signaling. Previous work using the tail incision and inflammatory models of pain has demonstrated that a single application of the glutaminase inhibitor, DON, into a surgical incision or the paw of arthritic animals results in pain relief. Even though this compound shows promise as a therapeutic agent, limited data exist regarding its dermal toxicity. As a first approach, we evaluated the effect of several concentrations of DON, on the viability, mitochondrial oxidative capacity and proliferation of rat skin fibroblasts, and then examined the effect of DON after incubation with human liver microsomes on proliferation. Finally, we evaluated DON treated rat skin (tail and hind paw) for cellular necrosis, inflammation and mitotic bodies. No significant effects (p > 0.05) of DON were noted on apoptosis, necrosis, and mitochondrial activity in experiments with cultured rat skin fibroblasts. Flow cytometry revealed the absence of apoptosis in cells treated at the IC50 of 232.5 μM. Enhanced toxicity post-exposure to human microsomes was not observed when compared to DON alone. The H&E staining of the rat skin revealed no obvious pathology in the DON treatment group (10 mM). DON has no/minimal cellular toxicity in vitro on dermal fibroblasts at concentrations that effectively provide analgesia. The local application of concentrations greater than the in vitro IC50 for DON revealed no in vivo skin toxicity. These data provide results indicating zero-to-minimal cellular toxicity with DON and support the further investigation of DON as an analgesic.
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Affiliation(s)
- Heith A Crosby
- Department of Anatomy and Cell Biology, Oklahoma State University-Center for Health Sciences, USA
| | - Michael Ihnat
- Department of Pharmaceutical Sciences, University of Oklahoma-Health Sciences Center, USA
| | - Kenneth E Miller
- Department of Anatomy and Cell Biology, Oklahoma State University-Center for Health Sciences, USA
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26
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Abstract
Flow cytometry is an essential tool to monitor DNA content and determine cell cycle distribution. Its utility in fission yeast reflects the ease of sample preparation, the stochiometric binding of the most popular DNA dyes (propidium iodide and Sytox Green), and ability to monitor cell size. However, the study of DNA replication with multicolour flow analysis has lagged behind its use in mammalian cells. We present basic and advanced protocols for analysis of DNA replication in fission yeast by flow cytometry including whole cell, nuclear "ghosts," two-color imaging with BrdU, and estimates of DNA synthesis using EdU.
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27
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Regulation of oxidative stress-induced cytotoxic processes of citrinin in the fission yeast Schizosaccharomyces pombe. Toxicon 2014; 90:155-66. [DOI: 10.1016/j.toxicon.2014.08.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 08/05/2014] [Accepted: 08/07/2014] [Indexed: 12/22/2022]
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28
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Vejrup-Hansen R, Fleck O, Landvad K, Fahnøe U, Broendum SS, Schreurs AS, Kragelund BB, Carr AM, Holmberg C, Nielsen O. Spd2 assists Spd1 in the modulation of ribonucleotide reductase architecture but does not regulate deoxynucleotide pools. J Cell Sci 2014; 127:2460-70. [PMID: 24652833 DOI: 10.1242/jcs.139816] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2024] Open
Abstract
In yeasts, small intrinsically disordered proteins (IDPs) modulate ribonucleotide reductase (RNR) activity to ensure an optimal supply of dNTPs for DNA synthesis. The Schizosaccharomyces pombe Spd1 protein can directly inhibit the large RNR subunit (R1), import the small subunit (R2) into the nucleus and induce an architectural change in the R1-R2 holocomplex. Here, we report the characterization of Spd2, a protein with sequence similarity to Spd1. We show that Spd2 is a CRL4(Cdt2)-controlled IDP that functions together with Spd1 in the DNA damage response and in modulation of RNR architecture. However, Spd2 does not regulate dNTP pools and R2 nuclear import. Furthermore, deletion of spd2 only weakly suppresses the Rad3(ATR) checkpoint dependency of CRL4(Cdt2) mutants. However, when we raised intracellular dNTP pools by inactivation of RNR feedback inhibition, deletion of spd2 could suppress the checkpoint dependency of CRL4(Cdt2) mutant cells to the same extent as deletion of spd1. Collectively, these observations suggest that Spd1 on its own regulates dNTP pools, whereas in combination with Spd2 it modulates RNR architecture and sensitizes cells to DNA damage.
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Affiliation(s)
- Rasmus Vejrup-Hansen
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen N., Denmark
| | - Oliver Fleck
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen N., Denmark NWCR Institute, School of Biological Sciences, Bangor University, Bangor, Gwynedd, LL57 2UW, UK
| | - Katrine Landvad
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen N., Denmark
| | - Ulrik Fahnøe
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen N., Denmark
| | - Sebastian S Broendum
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen N., Denmark
| | - Ann-Sofie Schreurs
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, East Sussex BN1 9RQ, UK
| | - Birthe B Kragelund
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen N., Denmark
| | - Antony M Carr
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, East Sussex BN1 9RQ, UK
| | - Christian Holmberg
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen N., Denmark
| | - Olaf Nielsen
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen N., Denmark
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Anda S, Boye E, Grallert B. Cell-cycle analyses using thymidine analogues in fission yeast. PLoS One 2014; 9:e88629. [PMID: 24551125 PMCID: PMC3923809 DOI: 10.1371/journal.pone.0088629] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 01/14/2014] [Indexed: 11/22/2022] Open
Abstract
Thymidine analogues are powerful tools when studying DNA synthesis including DNA replication, repair and recombination. However, these analogues have been reported to have severe effects on cell-cycle progression and growth, the very processes being investigated in most of these studies. Here, we have analyzed the effects of 5-ethynyl-2′-deoxyuridine (EdU) and 5-Chloro-2′-deoxyuridine (CldU) using fission yeast cells and optimized the labelling procedure. We find that both analogues affect the cell cycle, but that the effects can be mitigated by using the appropriate analogue, short pulses of labelling and low concentrations. In addition, we report sequential labelling of two consecutive S phases using EdU and 5-bromo-2′-deoxyuridine (BrdU). Furthermore, we show that detection of replicative DNA synthesis is much more sensitive than DNA-measurements by flow cytometry.
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Affiliation(s)
- Silje Anda
- Department of Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Montebello, Norway
| | - Erik Boye
- Department of Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Montebello, Norway
| | - Beata Grallert
- Department of Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Montebello, Norway
- * E-mail:
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30
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Tay YD, Patel A, Kaemena DF, Hagan IM. Mutation of a conserved residue enhances the sensitivity of analogue-sensitised kinases to generate a novel approach to the study of mitosis in fission yeast. J Cell Sci 2013; 126:5052-61. [PMID: 23986474 DOI: 10.1242/jcs.135301] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The chemical genetic strategy in which mutational enlargement of the ATP-binding site sensitises of a protein kinase to bulky ATP analogues has proved to be an elegant tool for the generation of conditional analogue-sensitive kinase alleles in a variety of model organisms. Here, we describe a novel substitution mutation in the kinase domain that can enhance the sensitivity of analogue-sensitive kinases. Substitution of a methionine residue to phenylalanine in the +2 position after HRDLKxxN motif of the subdomain VIb within the kinase domain markedly increased the sensitivities of the analogue-sensitive kinases to ATP analogues in three out of five S. pombe kinases (i.e. Plo1, Orb5 and Wee1) that harbor this conserved methionine residue. Kinome alignment established that a methionine residue is found at this site in 5-9% of kinases in key model organisms, suggesting that a broader application of this structural modification may enhance ATP analogue sensitivity of analogue-sensitive kinases in future studies. We also show that the enhanced sensitivity of the wee1.as8 allele in a cdc25.22 background can be exploited to generate highly synchronised mitotic and S phase progression at 36°C. Proof-of-principle experiments show how this novel synchronisation technique will prove of great use in the interrogation of the mitotic or S-phase functions through temperature sensitivity mutation of molecules of interest in fission yeast.
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Affiliation(s)
- Ye-Dee Tay
- CRUK Cell Division Group, Paterson Institute for Cancer Research, Wilmslow Road, Manchester M20 4BX, UK
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31
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Grallert A, Patel A, Tallada VA, Chan KY, Bagley S, Krapp A, Simanis V, Hagan IM. Centrosomal MPF triggers the mitotic and morphogenetic switches of fission yeast. Nat Cell Biol 2013; 15:88-95. [PMID: 23222840 PMCID: PMC3549529 DOI: 10.1038/ncb2633] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 10/29/2012] [Indexed: 01/18/2023]
Abstract
Activation of mitosis-promoting factor (MPF) drives mitotic commitment. In human cells active MPF appears first on centrosomes. We show that local activation of MPF on the equivalent organelle of fission yeast, the spindle pole body (SPB), promotes Polo kinase activity at the SPBs long before global MPF activation drives mitotic commitment. Artificially promoting MPF or Polo activity at various locations revealed that this local control of Plo1 activity on G2 phase SPBs dictates the timing of mitotic commitment. Cytokinesis of the rod-shaped fission yeast cell generates a naive, new, cell end. Growth is restricted to the experienced old end until a point in G2 phase called new end take off (NETO) when bipolar growth is triggered. NETO coincided with MPF activation of Plo1 on G2 phase SPBs (ref. 4). Both MPF and Polo activities were required for NETO and both induced NETO when ectopically activated at interphase SPBs. NETO promotion by MPF required polo. Thus, local MPF activation on G2 SPBs directs polo kinase to control at least two distinct and temporally separated, cell-cycle transitions at remote locations.
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Affiliation(s)
- Agnes Grallert
- CRUK Cell Division Group, Paterson Institute for Cancer Research, Wilmslow Road, Manchester, M20 4BX, UK
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32
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Krzyzanowski MK, Kozlowska E, Kozlowski P. Identification and functional analysis of the erh1(+) gene encoding enhancer of rudimentary homolog from the fission yeast Schizosaccharomyces pombe. PLoS One 2012; 7:e49059. [PMID: 23145069 PMCID: PMC3492181 DOI: 10.1371/journal.pone.0049059] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Accepted: 10/07/2012] [Indexed: 11/19/2022] Open
Abstract
The ERH gene encodes a highly conserved small nuclear protein with a unique amino acid sequence and three-dimensional structure but unknown function. The gene is present in animals, plants, and protists but to date has only been found in few fungi. Here we report that ERH homologs are also present in all four species from the genus Schizosaccharomyces, S. pombe, S. octosporus, S. cryophilus, and S. japonicus, which, however, are an exception in this respect among Ascomycota and Basidiomycota. The ERH protein sequence is moderately conserved within the genus (58% identity between S. pombe and S.japonicus), but the intron-rich genes have almost identical intron-exon organizations in all four species. In S. pombe, erh1(+) is expressed at a roughly constant level during vegetative growth and adaptation to unfavorable conditions such as nutrient limitation and hyperosmotic stress caused by sorbitol. Erh1p localizes preferentially to the nucleus with the exception of the nucleolus, but is also present in the cytoplasm. Cells lacking erh1(+) have an aberrant cell morphology and a comma-like shape when cultured to the stationary phase, and exhibit a delayed recovery from this phase followed by slower growth. Loss of erh1(+) in an auxotrophic background results in enhanced arrest in the G1 phase following nutritional stress, and also leads to hypersensitivity to agents inducing hyperosmotic stress (sorbitol), inhibiting DNA replication (hydroxyurea), and destabilizing the plasma membrane (SDS); this hypersensitivity can be abolished by expression of S. pombe erh1(+) and, to a lesser extent, S. japonicus erh1(+) or human ERH. Erh1p fails to interact with the human Ciz1 and PDIP46/SKAR proteins, known molecular partners of human ERH. Our data suggest that in Schizosaccharomyces sp. erh1(+) is non-essential for normal growth and Erh1p could play a role in response to adverse environmental conditions and in cell cycle regulation.
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Affiliation(s)
- Marek K. Krzyzanowski
- Department of Molecular Biology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Ewa Kozlowska
- Department of Immunology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Piotr Kozlowski
- Department of Molecular Biology, Faculty of Biology, University of Warsaw, Warsaw, Poland
- * E-mail:
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Bøe CA, Knutsen JHJ, Boye E, Grallert B. Hpz1 modulates the G1-S transition in fission yeast. PLoS One 2012; 7:e44539. [PMID: 22970243 PMCID: PMC3435320 DOI: 10.1371/journal.pone.0044539] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 08/03/2012] [Indexed: 11/29/2022] Open
Abstract
Here we characterize a novel protein in S. pombe. It has a high degree of homology with the Zn-finger domain of the human Poly(ADP-ribose) polymerase (PARP). Surprisingly, the gene for this protein is, in many fungi, fused with and in the same reading frame as that encoding Rad3, the homologue of the human ATR checkpoint protein. We name the protein Hpz1 (Homologue of PARP-type Zn-finger). Hpz1 does not possess PARP activity, but is important for resistance to ultraviolet light in the G1 phase and to treatment with hydroxyurea, a drug that arrests DNA replication forks in the S phase. However, we find no evidence of a checkpoint function of Hpz1. Furthermore, absence of Hpz1 results in an advancement of S-phase entry after a G1 arrest as well as earlier recovery from a hydroxyurea block. The hpz1 gene is expressed mainly in the G1 phase and Hpz1 is localized to the nucleus. We conclude that Hpz1 regulates the initiation of the S phase and may cooperate with Rad3 in this function.
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Affiliation(s)
- Cathrine A. Bøe
- Department of Cell Biology, Institute for Cancer Research, Oslo, Norway
- Institute for Molecular Biosciences, University of Oslo, Norway
| | - Jon Halvor J. Knutsen
- Department of Cell Biology, Institute for Cancer Research, Oslo, Norway
- Institute for Molecular Biosciences, University of Oslo, Norway
| | - Erik Boye
- Department of Cell Biology, Institute for Cancer Research, Oslo, Norway
- Institute for Molecular Biosciences, University of Oslo, Norway
| | - Beáta Grallert
- Department of Cell Biology, Institute for Cancer Research, Oslo, Norway
- Institute for Molecular Biosciences, University of Oslo, Norway
- * E-mail:
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Fujita I, Nishihara Y, Tanaka M, Tsujii H, Chikashige Y, Watanabe Y, Saito M, Ishikawa F, Hiraoka Y, Kanoh J. Telomere-nuclear envelope dissociation promoted by Rap1 phosphorylation ensures faithful chromosome segregation. Curr Biol 2012; 22:1932-7. [PMID: 22959349 DOI: 10.1016/j.cub.2012.08.019] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 06/28/2012] [Accepted: 08/09/2012] [Indexed: 11/19/2022]
Abstract
Efficient chromosomal movements are important for the fidelity of chromosome segregation during mitosis; however, movements are constrained during interphase by tethering of multiple domains to the nuclear envelope (NE). Higher eukaryotes undergo open mitosis accompanied by NE breakdown, enabling chromosomes to be released from the NE, whereas lower eukaryotes undergo closed mitosis, in which NE breakdown does not occur. Although the chromosomal movements in closed mitosis are thought to be restricted compared to open mitosis, the cells overcome this problem by an unknown mechanism that enables accurate chromosome segregation. Here, we report the spatiotemporal regulation of telomeres in Schizosaccharomyces pombe closed mitosis. We found that the telomeres, tethered to the NE during interphase, are transiently dissociated from the NE during mitosis. This dissociation from the NE is essential for accurate chromosome segregation because forced telomere tethering to the NE causes frequent chromosome loss. The phosphorylation of the telomere protein Rap1 during mitosis, primarily by Cdc2, impedes the interaction between Rap1 and Bqt4, a nuclear membrane protein, thereby inducing telomere dissociation from the NE. We propose that the telomere dissociation from the NE promoted by Rap1 phosphorylation is critical for the fidelity of chromosome segregation in closed mitosis.
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Affiliation(s)
- Ikumi Fujita
- Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
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Handa T, Kanke M, Takahashi TS, Nakagawa T, Masukata H. DNA polymerization-independent functions of DNA polymerase epsilon in assembly and progression of the replisome in fission yeast. Mol Biol Cell 2012; 23:3240-53. [PMID: 22718908 PMCID: PMC3418317 DOI: 10.1091/mbc.e12-05-0339] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
DNA Pol ε synthesizes the leading strands, following the CMG (Cdc45/Mcm2-7/GINS) helicase, although the N-terminal polymerase domain of the catalytic subunit, Cdc20 in fission yeast, is dispensable for viability. We show that the C-terminal domain of Cdc20 plays the noncatalytic essential roles in both the assembly and progression of CMG helicase. DNA polymerase epsilon (Pol ε) synthesizes the leading strands, following the CMG (Cdc45, Mcm2-7, and GINS [Go-Ichi-Nii-San]) helicase that translocates on the leading-strand template at eukaryotic replication forks. Although Pol ε is essential for the viability of fission and budding yeasts, the N-terminal polymerase domain of the catalytic subunit, Cdc20/Pol2, is dispensable for viability, leaving the following question: what is the essential role(s) of Pol ε? In this study, we investigated the essential roles of Pol ε using a temperature-sensitive mutant and a recently developed protein-depletion (off-aid) system in fission yeast. In cdc20-ct1 cells carrying mutations in the C-terminal domain of Cdc20, the CMG components, RPA, Pol α, and Pol δ were loaded onto replication origins, but Cdc45 did not translocate from the origins, suggesting that Pol ε is required for CMG helicase progression. In contrast, depletion of Cdc20 abolished the loading of GINS and Cdc45 onto origins, indicating that Pol ε is essential for assembly of the CMG complex. These results demonstrate that Pol ε plays essential roles in both the assembly and progression of CMG helicase.
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Affiliation(s)
- Tetsuya Handa
- Graduate School of Science, Osaka University, Osaka, Japan
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The S. pombe cytokinesis NDR kinase Sid2 activates Fin1 NIMA kinase to control mitotic commitment through Pom1/Wee1. Nat Cell Biol 2012; 14:738-45. [PMID: 22684255 PMCID: PMC4284365 DOI: 10.1038/ncb2514] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 05/08/2012] [Indexed: 01/24/2023]
Abstract
Mitotic exit integrates the reversal of the phosphorylation events initiated by mitotic kinases with a controlled cytokinesis event that cleaves the cell in two. The Mitotic Exit Network (MEN) of budding yeast regulates both processes, while the fission yeast equivalent, the Septum Initiation Network (SIN), only controls the execution of cytokinesis. The components and architecture of the SIN and MEN are highly conserved1. It is currently assumed that the functions of the core SIN/MEN components are restricted to their characterised roles at the end of mitosis. We now show that the NDR kinase component of the fission yeast SIN, Sid2/Mob1, acts independently of the other known SIN components in G2 phase of the cell cycle to control the timing of mitotic commitment. Sid2/Mob1 promotes mitotic commitment by directly activating the NIMA related kinase Fin1. Fin1’s activation promotes its own destruction, thereby making Fin1 activation a transient feature of G2 phase. This spike of Fin1 activation modulates the activity of the Pom1/Cdr1/Cdr2 geometry network towards Wee1.
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