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Chrupcala ML, Moseley JB. PP2A-B56 regulates Mid1 protein levels for proper cytokinesis in fission yeast. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.28.601230. [PMID: 38979265 PMCID: PMC11230426 DOI: 10.1101/2024.06.28.601230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Protein phosphorylation regulates many steps in the cell division process including cytokinesis. In the fission yeast S. pombe, the anillin-like protein Mid1 sets the cell division plane and is regulated by phosphorylation. Multiple protein kinases act on Mid1, but no protein phosphatases have been shown to regulate Mid1. Here, we discovered that the conserved protein phosphatase PP2A-B56 is required for proper cytokinesis by promoting Mid1 protein levels. We find that par1Δ cells lacking the primary B56 subunit divide asymmetrically due to the assembly of misplaced cytokinetic rings that slide toward cell tips. These par1Δ mutants have reduced whole-cell levels of Mid1 protein, leading to reduced Mid1 at the cytokinetic ring. Restoring proper Mid1 expression suppresses par1Δ cytokinesis defects. This work identifies a new PP2A-B56 pathway regulating cytokinesis through Mid1, with implications for control of cytokinesis in other organisms.
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Affiliation(s)
- Madeline L. Chrupcala
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover NH
| | - James B. Moseley
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover NH
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2
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Uysal Özdemir Ö, Krapp A, Mangeat B, Spaltenstein M, Simanis V. A role for the carbon source of the cell and protein kinase A in regulating the S. pombe septation initiation network. J Cell Sci 2024; 137:jcs261488. [PMID: 38197775 PMCID: PMC10906493 DOI: 10.1242/jcs.261488] [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: 07/13/2023] [Accepted: 11/24/2023] [Indexed: 01/11/2024] Open
Abstract
The septation initiation network (SIN) is a conserved signal transduction network, which is important for cytokinesis in Schizosaccharomyces pombe. The SIN component Etd1p is required for association of some SIN proteins with the spindle pole body (SPB) during anaphase and for contractile ring formation. We show that tethering of Cdc7p or Sid1p to the SIN scaffold Cdc11p at the SPB, rescues etd1-Δ. Analysis of a suppressor of the mutant etd1-M9 revealed that SIN signalling is influenced by the carbon source of the cell. Growth on a non-fermentable carbon source glycerol reduces the requirement for SIN signalling but does not bypass it. The decreased need for SIN signalling is mediated largely by reduction of protein kinase A activity, and it is phenocopied by deletion of pka1 on glucose medium. We conclude that protein kinase A is an important regulator of the SIN, and that SIN signalling is regulated by the carbon source of the cell.
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Affiliation(s)
- Özge Uysal Özdemir
- EPFL SV ISREC UPSIM, SV2.1830, Station 19, CH - 1015 Lausanne, Switzerland
| | - Andrea Krapp
- EPFL SV ISREC UPSIM, SV2.1830, Station 19, CH - 1015 Lausanne, Switzerland
| | - Bastien Mangeat
- EPFL SV PTECH PTEG, SV 1535 (Bâtiment SV), Station 19, CH-1015 Lausanne, Switzerland
| | - Marc Spaltenstein
- EPFL SV ISREC UPSIM, SV2.1830, Station 19, CH - 1015 Lausanne, Switzerland
| | - Viesturs Simanis
- EPFL SV ISREC UPSIM, SV2.1830, Station 19, CH - 1015 Lausanne, Switzerland
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3
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Chica N, Portantier M, Nyquist-Andersen M, Espada-Burriel S, Lopez-Aviles S. Uncoupling of Mitosis and Cytokinesis Upon a Prolonged Arrest in Metaphase Is Influenced by Protein Phosphatases and Mitotic Transcription in Fission Yeast. Front Cell Dev Biol 2022; 10:876810. [PMID: 35923846 PMCID: PMC9340479 DOI: 10.3389/fcell.2022.876810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 05/11/2022] [Indexed: 11/22/2022] Open
Abstract
Depletion of the Anaphase-Promoting Complex/Cyclosome (APC/C) activator Cdc20 arrests cells in metaphase with high levels of the mitotic cyclin (Cyclin B) and the Separase inhibitor Securin. In mammalian cells this arrest has been exploited for the treatment of cancer with drugs that engage the spindle assembly checkpoint and, recently, with chemical inhibitors of the APC/C. While most cells arrested in mitosis for prolonged periods undergo apoptosis, others skip cytokinesis and enter G1 with unsegregated chromosomes. This process, known as mitotic slippage, generates aneuploidy and increases genomic instability in the cancer cell. Here, we analyze the behavior of fission yeast cells arrested in mitosis through the transcriptional silencing of the Cdc20 homolog slp1. While depletion of slp1 readily halts cells in metaphase, this arrest is only transient and a majority of cells eventually undergo cytokinesis and show steady mitotic dephosphorylation. Notably, this occurs in the absence of Cyclin B (Cdc13) degradation. We investigate the involvement of phosphatase activity in these events and demonstrate that PP2A-B55Pab1 is required to prevent septation and, during the arrest, its CDK-mediated inhibition facilitates the induction of cytokinesis. In contrast, deletion of PP2A-B56Par1 completely abrogates septation. We show that this effect is partly due to this mutant entering mitosis with reduced CDK activity. Interestingly, both PP2A-B55Pab1 and PP2A-B56Par1, as well as Clp1 (the homolog of the budding yeast mitotic phosphatase Cdc14) are required for the dephosphorylation of mitotic substrates during the escape. Finally, we show that the mitotic transcriptional wave controlled by the RFX transcription factor Sak1 facilitates the induction of cytokinesis and also requires the activity of PP2A-B56Par1 in a mechanism independent of CDK.
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Affiliation(s)
- Nathalia Chica
- Centre for Molecular Medicine Norway (NCMM), Nordic EMBL partnership, Faculty of Medicine, University of Oslo, Oslo, Norway
- *Correspondence: Sandra Lopez-Aviles, ; Nathalia Chica,
| | - Marina Portantier
- Centre for Molecular Medicine Norway (NCMM), Nordic EMBL partnership, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Mari Nyquist-Andersen
- Centre for Molecular Medicine Norway (NCMM), Nordic EMBL partnership, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Silvia Espada-Burriel
- Centre for Molecular Medicine Norway (NCMM), Nordic EMBL partnership, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Sandra Lopez-Aviles
- Centre for Molecular Medicine Norway (NCMM), Nordic EMBL partnership, Faculty of Medicine, University of Oslo, Oslo, Norway
- Institute of Biosciences (IBV), Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway
- *Correspondence: Sandra Lopez-Aviles, ; Nathalia Chica,
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4
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Schutt KL, Moseley JB. The phosphatase inhibitor Sds23 regulates cell division symmetry in fission yeast. Mol Biol Cell 2019; 30:2880-2889. [PMID: 31553675 PMCID: PMC6822584 DOI: 10.1091/mbc.e19-05-0254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Animal and fungal cells divide through the assembly, anchoring, and constriction of a contractile actomyosin ring (CAR) during cytokinesis. The timing and position of the CAR must be tightly controlled to prevent defects in cell division, but many of the underlying signaling events remain unknown. The conserved heterotrimeric protein phosphatase PP2A controls the timing of events in mitosis, and upstream pathways including Greatwall-Ensa regulate PP2A activity. A role for PP2A in CAR regulation has been less clear, although loss of PP2A in yeast causes defects in cytokinesis. Here, we report that Sds23, an inhibitor of PP2A family protein phosphatases, promotes the symmetric division of fission yeast cells through spatial control of cytokinesis. We found that sds23∆ cells divide asymmetrically due to misplaced CAR assembly, followed by sliding of the CAR away from its assembly site. These mutant cells exhibit delayed recruitment of putative CAR anchoring proteins including the glucan synthase Bgs1. Our observations likely reflect a broader role for regulation of PP2A in cell polarity and cytokinesis because sds23∆ phenotypes were exacerbated when combined with mutations in the fission yeast Ensa homologue, Igo1. These results identify the PP2A regulatory network as a critical component in the signaling pathways coordinating cytokinesis.
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Affiliation(s)
- Katherine L Schutt
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - James B Moseley
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, NH 03755
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5
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Ariño J, Velázquez D, Casamayor A. Ser/Thr protein phosphatases in fungi: structure, regulation and function. MICROBIAL CELL 2019; 6:217-256. [PMID: 31114794 PMCID: PMC6506691 DOI: 10.15698/mic2019.05.677] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Reversible phospho-dephosphorylation of proteins is a major mechanism for the control of cellular functions. By large, Ser and Thr are the most frequently residues phosphorylated in eukar-yotes. Removal of phosphate from these amino acids is catalyzed by a large family of well-conserved enzymes, collectively called Ser/Thr protein phosphatases. The activity of these enzymes has an enormous impact on cellular functioning. In this work we pre-sent the members of this family in S. cerevisiae and other fungal species, and review the most recent findings concerning their regu-lation and the roles they play in the most diverse aspects of cell biology.
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Affiliation(s)
- Joaquín Ariño
- Departament de Bioquímica i Biologia Molecular and Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, Spain
| | - Diego Velázquez
- Departament de Bioquímica i Biologia Molecular and Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, Spain
| | - Antonio Casamayor
- Departament de Bioquímica i Biologia Molecular and Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, Spain
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Jiang P, Zheng S, Lu L. Mitotic-Spindle Organizing Protein MztA Mediates Septation Signaling by Suppressing the Regulatory Subunit of Protein Phosphatase 2A-ParA in Aspergillus nidulans. Front Microbiol 2018; 9:988. [PMID: 29774021 PMCID: PMC5951981 DOI: 10.3389/fmicb.2018.00988] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 04/27/2018] [Indexed: 12/20/2022] Open
Abstract
The proper timing and positioning of cytokinesis/septation is crucial for hyphal growth and conidiation in Aspergillus nidulans. The septation initiation network (SIN) components are a conserved spindle pole body (SPB) localized signaling cascade and the terminal kinase complex SidB-MobA, which must localize on the SPB in this pathway to trigger septation/cytokinesis. The regulatory subunit of phosphatase PP2A-ParA has been identified to be a negative regulator capable of inactivating the SIN. However, little is known about how ParA regulates the SIN pathway and whether ParA regulates the septum formation process through affecting the SPB-localized SIN proteins. In this study, through RNA-Seq and genetic approaches, we identified a new positive septation regulator, a putative mitotic-spindle organizing protein and a yeast Mzt1 homolog MztA, which acts antagonistically toward PP2A-ParA to coordinately regulate the SPB-localized SIN proteins SidB-MobA during septation. These findings imply that regulators, phosphatase PP2A-ParA and MztA counteract the septation function probably through balancing the polymerization and depolymerization of microtubules at the SPB.
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Affiliation(s)
- Ping Jiang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Shujun Zheng
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Ling Lu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing, China
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7
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Rayhan A, Faller A, Chevalier R, Mattice A, Karagiannis J. Using genetic buffering relationships identified in fission yeast to reveal susceptibilities in cells lacking hamartin or tuberin function. Biol Open 2018; 7:bio.031302. [PMID: 29343513 PMCID: PMC5827267 DOI: 10.1242/bio.031302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Tuberous sclerosis complex is an autosomal dominant disorder characterized by benign tumors arising from the abnormal activation of mTOR signaling in cells lacking TSC1 (hamartin) or TSC2 (tuberin) activity. To expand the genetic framework surrounding this group of growth regulators, we utilized the model eukaryote Schizosaccharomyces pombe to uncover and characterize genes that buffer the phenotypic effects of mutations in the orthologous tsc1 or tsc2 loci. Our study identified two genes: fft3 (encoding a DNA helicase) and ypa1 (encoding a peptidyle-prolyl cis/trans isomerase). While the deletion of fft3 or ypa1 has little effect in wild-type fission yeast cells, their loss in tsc1Δ or tsc2Δ backgrounds results in severe growth inhibition. These data suggest that the inhibition of Ypa1p or Fft3p might represent an 'Achilles' heel' of cells defective in hamartin/tuberin function. Furthermore, we demonstrate that the interaction between tsc1/tsc2 and ypa1 can be rescued through treatment with the mTOR inhibitor, torin-1, and that ypa1Δ cells are resistant to the glycolytic inhibitor, 2-deoxyglucose. This identifies ypa1 as a novel upstream regulator of mTOR and suggests that the effects of ypa1 loss, together with mTOR activation, combine to result in a cellular maladaptation in energy metabolism that is profoundly inhibitory to growth.
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Affiliation(s)
- Ashyad Rayhan
- Department of Biology, The University of Western Ontario, London, ON N6A-5B7, Canada
| | - Adam Faller
- Department of Biology, The University of Western Ontario, London, ON N6A-5B7, Canada
| | - Ryan Chevalier
- Department of Biology, The University of Western Ontario, London, ON N6A-5B7, Canada
| | - Alannah Mattice
- Department of Biology, The University of Western Ontario, London, ON N6A-5B7, Canada
| | - Jim Karagiannis
- Department of Biology, The University of Western Ontario, London, ON N6A-5B7, Canada
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8
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Sents W, Meeusen B, Kalev P, Radaelli E, Sagaert X, Miermans E, Haesen D, Lambrecht C, Dewerchin M, Carmeliet P, Westermarck J, Sablina A, Janssens V. PP2A Inactivation Mediated by PPP2R4 Haploinsufficiency Promotes Cancer Development. Cancer Res 2017; 77:6825-6837. [DOI: 10.1158/0008-5472.can-16-2911] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 08/19/2017] [Accepted: 10/13/2017] [Indexed: 11/16/2022]
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9
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Vishwanatha A, D'Souza CJM, Schweingruber ME. Genes Controlling 2-deoxyglucose Induced Lysis and Formation of Reactive Oxygen Species in Schizosaccharomyces pombe. Pol J Microbiol 2017; 66:393-396. [PMID: 29319508 DOI: 10.5604/01.3001.0010.4877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Schizosaccharomyces pombe cells of strains each carrying a deletion of one of the genes snf5, ypa1, pho7 and pas1 and of a strain overexpressing gene odr1, have been previously shown to grow in presence of the toxic glucose analogue 2-deoxyglucose (2-DG). Here we report that these genes control 2-DG induced lysis and are, with the exception of odr1, also involved in control of formation of reactive oxygen species (ROS) upon exposure of cells to H2O2. Lysis of deletion strains, but not of strain overexpressing odr1, is dependent on glucose concentration of the medium whereas ROS formation is glucose independent.
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Affiliation(s)
- Akshay Vishwanatha
- Department of Studies in Biochemistry, University of Mysore, Manasagangotri, Mysuru, Karnataka, India
| | - Cletus J M D'Souza
- Department of Studies in Biochemistry, University of Mysore, Manasagangotri, Mysuru, Karnataka, India
| | - Martin E Schweingruber
- Department of Studies in Biochemistry, University of Mysore, Manasagangotri, Mysuru, Karnataka, India
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10
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Deng L, Lee ME, Schutt KL, Moseley JB. Phosphatases Generate Signal Specificity Downstream of Ssp1 Kinase in Fission Yeast. Mol Cell Biol 2017; 37:e00494-16. [PMID: 28223368 PMCID: PMC5477550 DOI: 10.1128/mcb.00494-16] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 10/10/2016] [Accepted: 02/13/2017] [Indexed: 11/20/2022] Open
Abstract
AMPK-related protein kinases (ARKs) coordinate cell growth, proliferation, and migration with environmental status. It is unclear how specific ARKs are activated at specific times. In the fission yeast Schizosaccharomyces pombe, the CaMKK-like protein kinase Ssp1 promotes cell cycle progression by activating the ARK Cdr2 according to cell growth signals. Here, we demonstrate that Ssp1 activates a second ARK, Ssp2/AMPKα, for cell proliferation in low environmental glucose. Ssp1 activates these two related targets by the same biochemical mechanism: direct phosphorylation of a conserved residue in the activation loop (Cdr2-T166 and Ssp2-T189). Despite a shared upstream kinase and similar phosphorylation sites, Cdr2 and Ssp2 have distinct regulatory input cues and distinct functional outputs. We investigated this specificity and found that distinct protein phosphatases counteract Ssp1 activity toward its different substrates. We identified the PP6 family phosphatase Ppe1 as the primary phosphatase for Ssp2-T189 dephosphorylation. The phosphatase inhibitor Sds23 acts upstream of PP6 to regulate Ssp2-T189 phosphorylation in a manner that depends on energy but not on the intact AMPK heterotrimer. In contrast, Cdr2-T166 phosphorylation is regulated by protein phosphatase 2A but not by the Sds23-PP6 pathway. Thus, our study provides a phosphatase-driven mechanism to induce specific physiological responses downstream of a master protein kinase.
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Affiliation(s)
- Lin Deng
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Mid Eum Lee
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Katherine L Schutt
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - James B Moseley
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
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11
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Vishwanatha A, Rallis C, Bevkal Subramanyaswamy S, D'Souza CJM, Bähler J, Schweingruber ME. Identification of nuclear genes affecting 2-Deoxyglucose resistance in Schizosaccharomyces pombe. FEMS Yeast Res 2016; 16:fow061. [PMID: 27481777 PMCID: PMC5452730 DOI: 10.1093/femsyr/fow061] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/25/2016] [Indexed: 01/16/2023] Open
Abstract
2-Deoxyglucose (2-DG) is a toxic glucose analog. To identify genes involved in 2-DG toxicity in Schizosaccharomyces pombe, we screened a wild-type overexpression library for genes which render cells 2-DG resistant. A gene we termed odr1, encoding an uncharacterized hydrolase, led to strong resistance and altered invertase expression when overexpressed. We speculate that Odr1 neutralizes the toxic form of 2-DG, similar to the Saccharomyces cerevisiae Dog1 and Dog2 phosphatases which dephosphorylate 2-DG-6-phosphate synthesized by hexokinase. In a complementary approach, we screened a haploid deletion library to identify 2-DG-resistant mutants. This screen identified the genes snf5, ypa1, pas1 and pho7. In liquid medium, deletions of these genes conferred 2-DG resistance preferentially under glucose-repressed conditions. The deletion mutants expressed invertase activity more constitutively than the control strain, indicating defects in the control of glucose repression. No S. cerevisiae orthologs of the pho7 gene is known, and no 2-DG resistance has been reported for any of the deletion mutants of the other genes identified here. Moreover, 2-DG leads to derepressed invertase activity in S. pombe, while in S. cerevisiae it becomes repressed. Taken together, these findings suggest that mechanisms involved in 2-DG resistance differ between budding and fission yeasts.
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Affiliation(s)
- Akshay Vishwanatha
- Department of Studies in Biochemistry, University of Mysore, Manasagangotri, Mysuru 570 006, Karnataka, India
| | - Charalampos Rallis
- Research Department of Genetics, Evolution and Environment, UCL Institute of Healthy Ageing, University College London, London WC1E 6BT, UK
| | - Shubha Bevkal Subramanyaswamy
- Department of Studies in Biochemistry, University of Mysore, Manasagangotri, Mysuru 570 006, Karnataka, India Institute of Cell Biology, University of Bern, Baltzerstrasse 4, CH-3012 Bern, Switzerland
| | | | - Jürg Bähler
- Research Department of Genetics, Evolution and Environment, UCL Institute of Healthy Ageing, University College London, London WC1E 6BT, UK
| | - Martin Ernst Schweingruber
- Department of Studies in Biochemistry, University of Mysore, Manasagangotri, Mysuru 570 006, Karnataka, India
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Functional Crosstalk between the PP2A and SUMO Pathways Revealed by Analysis of STUbL Suppressor, razor 1-1. PLoS Genet 2016; 12:e1006165. [PMID: 27398807 PMCID: PMC4939958 DOI: 10.1371/journal.pgen.1006165] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 06/11/2016] [Indexed: 12/04/2022] Open
Abstract
Posttranslational modifications (PTMs) provide dynamic regulation of the cellular proteome, which is critical for both normal cell growth and for orchestrating rapid responses to environmental stresses, e.g. genotoxins. Key PTMs include ubiquitin, the Small Ubiquitin-like MOdifier SUMO, and phosphorylation. Recently, SUMO-targeted ubiquitin ligases (STUbLs) were found to integrate signaling through the SUMO and ubiquitin pathways. In general, STUbLs are recruited to target proteins decorated with poly-SUMO chains to ubiquitinate them and drive either their extraction from protein complexes, and/or their degradation at the proteasome. In fission yeast, reducing or preventing the formation of SUMO chains can circumvent the essential and DNA damage response functions of STUbL. This result indicates that whilst some STUbL "targets" have been identified, the crucial function of STUbL is to antagonize SUMO chain formation. Herein, by screening for additional STUbL suppressors, we reveal crosstalk between the serine/threonine phosphatase PP2A-Pab1B55 and the SUMO pathway. A hypomorphic Pab1B55 mutant not only suppresses STUbL dysfunction, but also mitigates the phenotypes associated with deletion of the SUMO protease Ulp2, or mutation of the STUbL cofactor Rad60. Together, our results reveal a novel role for PP2A-Pab1B55 in modulating SUMO pathway output, acting in parallel to known critical regulators of SUMOylation homeostasis. Given the broad evolutionary functional conservation of the PP2A and SUMO pathways, our results could be relevant to the ongoing attempts to therapeutically target these factors. Posttranslational modifiers (PTMs) orchestrate the proteins and processes that control genome stability and cell growth. Accordingly, deregulation of PTMs causes disease, but can also be harnessed therapeutically. Crosstalk between PTMs is widespread, and acts to increase specificity and selectivity in signal transduction. Such crosstalk exists between two major PTMs, SUMO and ubiquitin, wherein a SUMO-targeted ubiquitin ligase (STUbL) can additionally mark SUMO-modified proteins with ubiquitin. Thereby, STUbL generates a hybrid SUMO-ubiquitin signal that is recognized by selective effectors, which can extract proteins from complexes and/or direct their degradation at the proteasome. STUbL function is critical to maintain genome stability, and it also mediates the therapeutic effects of arsenic trioxide in leukemia treatment. Therefore, a full appreciation of STUbL regulation and integration with other PTMs is warranted. Unexpectedly, we find that reduced activity of PP2A, a major cellular phosphatase, compensates for STUbL inactivation. Our results indicate that PP2A-regulated phosphorylation reduces the SUMO chain output of the SUMO pathway, thus reducing cellular dependency on STUbL and the functionally related factors Ulp2 and Rad60. Our data not only reveal a striking level of plasticity in signaling through certain PTMs, but also highlight potential "escape" mechanisms for SUMO pathway-based therapies.
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13
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Simanis V. Pombe's thirteen - control of fission yeast cell division by the septation initiation network. J Cell Sci 2015; 128:1465-74. [PMID: 25690009 DOI: 10.1242/jcs.094821] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The septation initiation network (SIN) regulates aspects of cell growth and division in Schizosaccharomyces pombe and is essential for cytokinesis. Insufficient signalling results in improper assembly of the contractile ring and failure of cytokinesis, generating multinucleated cells, whereas too much SIN signalling uncouples cytokinesis from the rest of the cell cycle. SIN signalling is therefore tightly controlled to coordinate cytokinesis with chromosome segregation. Signalling originates from the cytoplasmic face of the spindle pole body (SPB), and asymmetric localisation of some SIN proteins to one of the two SPBs during mitosis is important for regulation of the SIN. Recent studies have identified in vivo substrates of the SIN, which include components involved in mitotic control, those of the contractile ring and elements of the signalling pathway regulating polarised growth. The SIN is also required for spore formation following meiosis. This has provided insights into how the SIN performs its diverse functions in the cell cycle and shed new light on its regulation.
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Affiliation(s)
- Viesturs Simanis
- École Polytechnique Fédérale de Lausanne School of Life Sciences (EPFL-SV), Swiss Institute For Experimental Cancer Research (ISREC), UPSIM, SV2.1830, Station 19, CH-1015 Lausanne, Switzerland
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14
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Wachowicz P, Chasapi A, Krapp A, Cano Del Rosario E, Schmitter D, Sage D, Unser M, Xenarios I, Rougemont J, Simanis V. Analysis of S. pombe SIN protein association to the SPB reveals two genetically separable states of the SIN. J Cell Sci 2014; 128:741-54. [PMID: 25501816 DOI: 10.1242/jcs.160150] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Schizosaccharomyces pombe septation initiation network (SIN) regulates cytokinesis, and asymmetric association of SIN proteins with the mitotic spindle pole bodies (SPBs) is important for its regulation. Here, we have used semi-automated image analysis to study SIN proteins in large numbers of wild-type and mutant cells. Our principal conclusions are: first, that the association of Cdc7p with the SPBs in early mitosis is frequently asymmetric, with a bias in favour of the new SPB; second, that the early association of Cdc7p-GFP to the SPB depends on Plo1p but not Spg1p, and is unaffected by mutations that influence its asymmetry in anaphase; third, that Cdc7p asymmetry in anaphase B is delayed by Pom1p and by activation of the spindle assembly checkpoint, and is promoted by Rad24p; and fourth, that the length of the spindle, expressed as a fraction of the length of the cell, at which Cdc7p becomes asymmetric is similar in cells dividing at different sizes. These data reveal that multiple regulatory mechanisms control the SIN in mitosis and lead us to propose a two-state model to describe the SIN.
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Affiliation(s)
- Paulina Wachowicz
- Cell cycle control laboratory, Ecole Polytechnique Fédérale de Lausanne (EPFL), SV-ISREC, 1015 Lausanne, Switzerland
| | - Anastasia Chasapi
- Swiss-Prot. Group and Vital-IT Group, Swiss Institute of Bioinformatics (SIB), 1015 Lausanne, Switzerland
| | - Andrea Krapp
- Cell cycle control laboratory, Ecole Polytechnique Fédérale de Lausanne (EPFL), SV-ISREC, 1015 Lausanne, Switzerland
| | - Elena Cano Del Rosario
- Cell cycle control laboratory, Ecole Polytechnique Fédérale de Lausanne (EPFL), SV-ISREC, 1015 Lausanne, Switzerland
| | - Daniel Schmitter
- Biomedical Imaging Group, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Daniel Sage
- Biomedical Imaging Group, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Michael Unser
- Biomedical Imaging Group, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Ioannis Xenarios
- Swiss-Prot. Group and Vital-IT Group, Swiss Institute of Bioinformatics (SIB), 1015 Lausanne, Switzerland
| | - Jacques Rougemont
- Bioinformatics and Biostatistics Core Facility, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Viesturs Simanis
- Cell cycle control laboratory, Ecole Polytechnique Fédérale de Lausanne (EPFL), SV-ISREC, 1015 Lausanne, Switzerland
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15
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Bernal M, Zhurinsky J, Iglesias-Romero AB, Sanchez-Romero MA, Flor-Parra I, Tomas-Gallardo L, Perez-Pulido AJ, Jimenez J, Daga RR. Proteome-wide search for PP2A substrates in fission yeast. Proteomics 2014; 14:1367-80. [PMID: 24634168 DOI: 10.1002/pmic.201300136] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 02/19/2014] [Accepted: 03/07/2014] [Indexed: 11/10/2022]
Abstract
PP2A (protein phosphatase 2A) is a major phosphatase in eukaryotic cells that plays an essential role in many processes. PP2A mutations in Schizosaccharomyces pombe result in defects of cell cycle control, cytokinesis and morphogenesis. Which PP2A substrates are responsible for these changes is not known. In this work, we searched for PP2A substrates in S. pombe using two approaches, 2D-DIGE analysis of PP2A complex mutants and identification of PP2A interacting proteins. In both cases, we used MS to identify proteins of interest. In the DIGE experiment, we compared proteomes of wild-type S. pombe, deletion of pta2, the phosphoactivator of the PP2A catalytic subunit, and pab1-4, a mutant of B-type PP2A regulatory subunit. A total of 1742 protein spots were reproducibly resolved by 2D-DIGE and 51 spots demonstrated significant changes between PP2A mutants and the wild-type control. MS analysis of these spots identified 27 proteins that include key regulators of glycerol synthesis, carbon metabolism, amino acid biosyntesis, vitamin production, and protein folding. Importantly, we independently identified a subset of these proteins as PP2A binding partners by affinity precipitation, suggesting they may be direct targets of PP2A. We have validated our approach by demonstrating that phosphorylation of Gpd1, a key enzyme in glycerol biogenesis, is regulated by PP2A and that ability of cells to respond to osmotic stress by synthesizing glycerol is compromised in the PP2A mutants. Our work contributes to a better understanding of PP2A function and identifies potential PP2A substrates.
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Affiliation(s)
- Manuel Bernal
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas, Junta de Andalucía, Sevilla, Spain
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16
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Krapp A, Simanis V. Dma1-dependent degradation of Septation Initiation Network proteins during meiosis in Schizosaccharomyces pombe. J Cell Sci 2014; 127:3149-61. [DOI: 10.1242/jcs.148585] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Schizosaccharomyces pombe septation initiation network (SIN) is required for cytokinesis during vegetative growth and spore formation during meiosis. Regulation of the SIN during mitosis has been studied extensively, but less is known about its meiotic regulation. Here, we show that several aspects of the SIN regulation differ between mitosis and meiosis. First, the presence of GTP-bound spg1p is not the main determinant of the timing of cdc7p and sid1p association with the SPB during meiosis. Second, the localisation dependencies of SIN proteins differ from those in mitotic cells, suggesting a modified functional organisation of the SIN during meiosis. Third, there is stage-specific degradation of SIN components in meiosis; byr4p is degraded after meiosis I, while the degradation of cdc7p, cdc11p and sid4p occurs after the second meiotic division and depends upon the ubiquitin ligase dma1p. Finally, dma1p-dependent degradation is not restricted to the SIN, for we show that dma1p is needed for the degradation of mcp6p/hrs1p in meiosis I. Together, these data suggest that stage-specific targetted proteolysis will play an important role in regulating meiotic progression.
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17
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Smith TC, Fridy PC, Li Y, Basil S, Arjun S, Friesen RM, Leszyk J, Chait BT, Rout MP, Luna EJ. Supervillin binding to myosin II and synergism with anillin are required for cytokinesis. Mol Biol Cell 2013; 24:3603-19. [PMID: 24088567 PMCID: PMC3842989 DOI: 10.1091/mbc.e12-10-0714] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Cytokinesis, the process by which cytoplasm is apportioned between dividing daughter cells, requires coordination of myosin II function, membrane trafficking, and central spindle organization. Most known regulators act during late cytokinesis; a few, including the myosin II-binding proteins anillin and supervillin, act earlier. Anillin's role in scaffolding the membrane cortex with the central spindle is well established, but the mechanism of supervillin action is relatively uncharacterized. We show here that two regions within supervillin affect cell division: residues 831-1281, which bind central spindle proteins, and residues 1-170, which bind the myosin II heavy chain (MHC) and the long form of myosin light-chain kinase. MHC binding is required to rescue supervillin deficiency, and mutagenesis of this site creates a dominant-negative phenotype. Supervillin concentrates activated and total myosin II at the furrow, and simultaneous knockdown of supervillin and anillin additively increases cell division failure. Knockdown of either protein causes mislocalization of the other, and endogenous anillin increases upon supervillin knockdown. Proteomic identification of interaction partners recovered using a high-affinity green fluorescent protein nanobody suggests that supervillin and anillin regulate the myosin II and actin cortical cytoskeletons through separate pathways. We conclude that supervillin and anillin play complementary roles during vertebrate cytokinesis.
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Affiliation(s)
- Tara C Smith
- Program in Cell and Developmental Dynamics, Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655 Laboratory of Cellular and Structural Biology, Rockefeller University, New York, NY 10065 Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, Rockefeller University, New York, NY 10065 Proteomics and Mass Spectrometry Facility, University of Massachusetts Medical School, Shrewsbury, MA 01545
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18
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Zhu YH, Ye Y, Wu Z, Wu JQ. Cooperation between Rho-GEF Gef2 and its binding partner Nod1 in the regulation of fission yeast cytokinesis. Mol Biol Cell 2013; 24:3187-204. [PMID: 23966468 PMCID: PMC3806657 DOI: 10.1091/mbc.e13-06-0301] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Previous results showed that putative Rho-GEF Gef2 regulates division-site positioning during early cytokinesis in fission yeast. Here Nod1 is identified as a binding partner of Gef2. The two proteins form a complex to regulate division-site positioning and contractile-ring maintenance. In addition, Gef2 binds to GTPases Rho1, Rho4, and Rho5 in vitro. Cytokinesis is the last step of the cell-division cycle, which requires precise spatial and temporal regulation to ensure genetic stability. Rho guanine nucleotide exchange factors (Rho GEFs) and Rho GTPases are among the key regulators of cytokinesis. We previously found that putative Rho-GEF Gef2 coordinates with Polo kinase Plo1 to control the medial cortical localization of anillin-like protein Mid1 in fission yeast. Here we show that an adaptor protein, Nod1, colocalizes with Gef2 in the contractile ring and its precursor cortical nodes. Like gef2∆, nod1∆ has strong genetic interactions with various cytokinesis mutants involved in division-site positioning, suggesting a role of Nod1 in early cytokinesis. We find that Nod1 and Gef2 interact through the C-termini, which is important for their localization. The contractile-ring localization of Nod1 and Gef2 also depends on the interaction between Nod1 and the F-BAR protein Cdc15, where the Nod1/Gef2 complex plays a role in contractile-ring maintenance and affects the septation initiation network. Moreover, Gef2 binds to purified GTPases Rho1, Rho4, and Rho5 in vitro. Taken together, our data indicate that Nod1 and Gef2 function cooperatively in a protein complex to regulate fission yeast cytokinesis.
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Affiliation(s)
- Yi-Hua Zhu
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210 Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, OH 43210 Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210
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19
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Johnson AE, McCollum D, Gould KL. Polar opposites: Fine-tuning cytokinesis through SIN asymmetry. Cytoskeleton (Hoboken) 2012; 69:686-99. [PMID: 22786806 PMCID: PMC3478943 DOI: 10.1002/cm.21044] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 06/04/2012] [Indexed: 01/10/2023]
Abstract
Mitotic exit and cell division must be spatially and temporally integrated to facilitate equal division of genetic material between daughter cells. In the fission yeast, Schizosaccharomyces pombe, a spindle pole body (SPB) localized signaling cascade termed the septation initiation network (SIN) couples mitotic exit with cytokinesis. The SIN is controlled at many levels to ensure that cytokinesis is executed once per cell cycle and only after cells segregate their DNA. An interesting facet of the SIN is that its activity is asymmetric on the two SPBs during anaphase; however, how and why the SIN is asymmetric has remained elusive. Many key factors controlling SIN asymmetry have now been identified, shedding light on the significance of SIN asymmetry in regulating cytokinesis. In this review, we highlight recent advances in our understanding of SIN regulation, with an emphasis on how SIN asymmetry is achieved and how this aspect of SIN regulation fine-tunes cytokinesis.
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Affiliation(s)
- Alyssa E Johnson
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, USA
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