1
|
Sen MG, Sanislav O, Fisher PR, Annesley SJ. The Multifaceted Interactions of Dictyostelium Atg1 with Mitochondrial Function, Endocytosis, Growth, and Development. Cells 2024; 13:1191. [PMID: 39056773 PMCID: PMC11274416 DOI: 10.3390/cells13141191] [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] [Received: 05/29/2024] [Revised: 07/04/2024] [Accepted: 07/09/2024] [Indexed: 07/28/2024] Open
Abstract
Autophagy is a degradative recycling process central to the maintenance of homeostasis in all eukaryotes. By ensuring the degradation of damaged mitochondria, it plays a key role in maintaining mitochondrial health and function. Of the highly conserved autophagy proteins, autophagy-related protein 1 (Atg1) is essential to the process. The involvement of these proteins in intracellular signalling pathways, including those involving mitochondrial function, are still being elucidated. Here the role of Atg1 was investigated in the simple model organism Dictyostelium discoideum using an atg1 null mutant and mutants overexpressing or antisense-inhibiting atg1. When evaluated against the well-characterised outcomes of mitochondrial dysfunction in this model, altered atg1 expression resulted in an unconventional set of phenotypic outcomes in growth, endocytosis, multicellular development, and mitochondrial homeostasis. The findings here show that Atg1 is involved in a tightly regulated signal transduction pathway coordinating energy-consuming processes such as cell growth and multicellular development, along with nutrient status and energy production. Furthermore, Atg1's effects on energy homeostasis indicate a peripheral ancillary role in the mitochondrial signalling network, with effects on energy balance rather than direct effects on electron transport chain function. Further research is required to tease out these complex networks. Nevertheless, this study adds further evidence to the theory that autophagy and mitochondrial signalling are not opposing but rather linked, yet strictly controlled, homeostatic mechanisms.
Collapse
Affiliation(s)
| | | | | | - Sarah Jane Annesley
- Department of Microbiology, Anatomy, Physiology and Pharmacology, La Trobe University, Bundoora, Melbourne 3086, Australia; (M.G.S.); (O.S.); (P.R.F.)
| |
Collapse
|
2
|
Zemlianski V, Marešová A, Princová J, Holič R, Häsler R, Ramos Del Río MJ, Lhoste L, Zarechyntsava M, Převorovský M. Nitrogen availability is important for preventing catastrophic mitosis in fission yeast. J Cell Sci 2024; 137:jcs262196. [PMID: 38780300 DOI: 10.1242/jcs.262196] [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: 04/10/2024] [Accepted: 05/16/2024] [Indexed: 05/25/2024] Open
Abstract
Mitosis is a crucial stage in the cell cycle, controlled by a vast network of regulators responding to multiple internal and external factors. The fission yeast Schizosaccharomyces pombe demonstrates catastrophic mitotic phenotypes due to mutations or drug treatments. One of the factors provoking catastrophic mitosis is a disturbed lipid metabolism, resulting from, for example, mutations in the acetyl-CoA/biotin carboxylase (cut6), fatty acid synthase (fas2, also known as lsd1) or transcriptional regulator of lipid metabolism (cbf11) genes, as well as treatment with inhibitors of fatty acid synthesis. It has been previously shown that mitotic fidelity in lipid metabolism mutants can be partially rescued by ammonium chloride supplementation. In this study, we demonstrate that mitotic fidelity can be improved by multiple nitrogen sources. Moreover, this improvement is not limited to lipid metabolism disturbances but also applies to a number of unrelated mitotic mutants. Interestingly, the partial rescue is not achieved by restoring the lipid metabolism state, but rather indirectly. Our results highlight a novel role for nitrogen availability in mitotic fidelity.
Collapse
Affiliation(s)
- Viacheslav Zemlianski
- Department of Cell Biology, Faculty of Science, Charles University, Viničná 7, 128 00 Prague 2, Czechia
| | - Anna Marešová
- Department of Cell Biology, Faculty of Science, Charles University, Viničná 7, 128 00 Prague 2, Czechia
| | - Jarmila Princová
- Department of Cell Biology, Faculty of Science, Charles University, Viničná 7, 128 00 Prague 2, Czechia
| | - Roman Holič
- Centre of Biosciences SAS, Institute of Animal Biochemistry and Genetics, Dúbravská cesta 9, 840 05 Bratislava, Slovak Republic
| | - Robert Häsler
- Center for Inflammatory Skin Diseases, Department of Dermatology and Allergy, University Hospital Schleswig-Holstein, Campus Kiel, Rosalind-Franklin-Straße 9, 24105 Kiel, Germany
| | - Manuel José Ramos Del Río
- Department of Cell Biology, Faculty of Science, Charles University, Viničná 7, 128 00 Prague 2, Czechia
| | - Laurane Lhoste
- Department of Cell Biology, Faculty of Science, Charles University, Viničná 7, 128 00 Prague 2, Czechia
| | - Maryia Zarechyntsava
- Department of Cell Biology, Faculty of Science, Charles University, Viničná 7, 128 00 Prague 2, Czechia
| | - Martin Převorovský
- Department of Cell Biology, Faculty of Science, Charles University, Viničná 7, 128 00 Prague 2, Czechia
| |
Collapse
|
3
|
Sarkar P, Misra S, Ghosal A, Mukherjee S, Ghosh A, Sundaram G. Glucose to lactate shift reprograms CDK-dependent mitotic decisions and its communication with MAPK Sty1 in Schizosaccharomyces pombe. Biol Open 2023; 12:bio060145. [PMID: 37787465 PMCID: PMC10618596 DOI: 10.1242/bio.060145] [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: 09/08/2023] [Accepted: 09/25/2023] [Indexed: 10/04/2023] Open
Abstract
Cell cycle regulation in response to biochemical cues is a fundamental event associated with many diseases. The regulation of such responses in complex metabolic environments is poorly understood. This study reveals unknown aspects of the metabolic regulation of cell division in Schizosaccharomyces pombe. We show that changing the carbon source from glucose to lactic acid alters the functions of the cyclin-dependent kinase (CDK) Cdc2 and mitogen-activated protein kinase (MAPK) Sty1, leading to unanticipated outcomes in the behavior and fate of such cells. Functional communication of Cdc2 with Sty1 is known to be an integral part of the cellular response to aberrant Cdc2 activity in S. pombe. Our results show that cross-talk between Cdc2 and Sty1, and the consequent Sty1-dependent regulation of Cdc2 activity, appears to be compromised and the relationship between Cdc2 activity and mitotic timing is also reversed in the presence of lactate. We also show that the biochemical status of cells under these conditions is an important determinant of the altered molecular functions mentioned above as well as the altered behavior of these cells.
Collapse
Affiliation(s)
- Priyanka Sarkar
- Department of Biochemistry, University of Calcutta, Kolkata 700019, India
| | - Susmita Misra
- Department of Biochemistry, University of Calcutta, Kolkata 700019, India
| | - Agamani Ghosal
- Department of Biochemistry, University of Calcutta, Kolkata 700019, India
| | | | - Alok Ghosh
- Department of Biochemistry, University of Calcutta, Kolkata 700019, India
| | | |
Collapse
|
4
|
Salat-Canela C, Pérez P, Ayté J, Hidalgo E. Stress-induced cell depolarization through the MAP kinase-Cdc42 axis. Trends Cell Biol 2023; 33:124-137. [PMID: 35773059 DOI: 10.1016/j.tcb.2022.06.004] [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] [Received: 04/12/2022] [Revised: 06/01/2022] [Accepted: 06/08/2022] [Indexed: 01/25/2023]
Abstract
General stress responses, which sense environmental or endogenous signals, aim at promoting cell survival and fitness during adverse conditions. In eukaryotes, mitogen-activated protein (MAP) kinase-driven cascades trigger a shift in the cell's gene expression program as a cellular adaptation to stress. Here, we review another aspect of activated MAP kinase cascades reported in fission yeast: the transient inhibition of cell polarity in response to oxidative stress. The phosphorylation by a stress-activated MAP kinase of regulators of the GTPase cell division cycle 42 (Cdc42) causes a transient inhibition of polarized cell growth. The formation of growth sites depends on limiting and essential polarity components. We summarize here some processes in which inhibition of Cdc42 may be a general mechanism to regulate polarized growth also under physiological conditions.
Collapse
Affiliation(s)
- Clàudia Salat-Canela
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, C/Dr. Aiguader 88, 08003, Barcelona, Spain
| | - Pilar Pérez
- Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas, Universidad de Salamanca, 37007 Salamanca, Spain
| | - José Ayté
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, C/Dr. Aiguader 88, 08003, Barcelona, Spain.
| | - Elena Hidalgo
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, C/Dr. Aiguader 88, 08003, Barcelona, Spain.
| |
Collapse
|
5
|
Bertaux F, Kleijn IT, Marguerat S, Shahrezaei V. Fission yeast obeys a linear size law under nutrient titration. MICROPUBLICATION BIOLOGY 2023; 2023:10.17912/micropub.biology.000833. [PMID: 37193545 PMCID: PMC10182418 DOI: 10.17912/micropub.biology.000833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 04/27/2023] [Accepted: 04/24/2023] [Indexed: 05/18/2023]
Abstract
Steady-state cell size and geometry depend on growth conditions. Here, we use an experimental setup based on continuous culture and single-cell imaging to study how cell volume, length, width and surface-to-volume ratio vary across a range of growth conditions including nitrogen and carbon titration, the choice of nitrogen source, and translation inhibition. Overall, we find cell geometry is not fully determined by growth rate and depends on the specific mode of growth rate modulation. However, under nitrogen and carbon titrations, we observe that the cell volume and the growth rate follow the same linear scaling.
Collapse
Affiliation(s)
- François Bertaux
- MRC London Institute of Medical Sciences, London, England, United Kingdom
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, England, United Kingdom
- Department of Mathematics, Faculty of Natural Sciences, Imperial College London, London, England, United Kingdom
| | - Istvan T. Kleijn
- MRC London Institute of Medical Sciences, London, England, United Kingdom
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, England, United Kingdom
- Department of Mathematics, Faculty of Natural Sciences, Imperial College London, London, England, United Kingdom
| | - Samuel Marguerat
- MRC London Institute of Medical Sciences, London, England, United Kingdom
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, England, United Kingdom
- Current address: UCL Cancer Institute, University College London, London, England, United Kingdom
- Correspondence to: Samuel Marguerat (
)
| | - Vahid Shahrezaei
- Department of Mathematics, Faculty of Natural Sciences, Imperial College London, London, England, United Kingdom
- Correspondence to: Vahid Shahrezaei (
)
| |
Collapse
|
6
|
Solis-Ortiz CS, Gonzalez-Bernal J, Kido-Díaz HA, Peña-Uribe CA, López-Bucio JS, López-Bucio J, Guevara-García ÁA, García-Pineda E, Villegas J, Campos-García J, Reyes de La Cruz H. Bacterial cyclodipeptides elicit Arabidopsis thaliana immune responses reducing the pathogenic effects of Pseudomonas aeruginosa PAO1 strains on plant development. JOURNAL OF PLANT PHYSIOLOGY 2022; 275:153738. [PMID: 35690030 DOI: 10.1016/j.jplph.2022.153738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 05/27/2022] [Accepted: 05/27/2022] [Indexed: 06/15/2023]
Abstract
Plants being sessile organisms are exposed to various biotic and abiotic factors, thus causing stress. The Pseudomonas aeruginosa bacterium is an opportunistic pathogen for animals, insects, and plants. Direct exposure of Arabidopsis thaliana to the P. aeruginosa PAO1 strain induces plant death by producing a wide variety of virulence factors, which are regulated mainly by quorum sensing systems. Besides virulence factors, P. aeruginosa PAO1 also produces cyclodipeptides (CDPs), which possess auxin-like activity and promote plant growth through activation of the target of the rapamycin (AtTOR) pathway. On the other hand, plant defense mechanisms are regulated through the production of phytohormones, such as salicylic acid (SA) and jasmonic acid (JA), which are induced in response to pathogen-associated molecular patterns (PAMPs), activating defense genes associated with SA and JA such as PATHOGENESIS-RELATED-1 (PR-1) and LIPOXYGENASE2 (LOX2), respectively. PR proteins are suggested to play critical roles in coordinating the Systemic Acquired Resistance (SAR). In contrast, LOX proteins (LOX2, LOX3, and LOX4) have been associated with the production of JA by producing its precursors, oxylipins. The activation of defense mechanisms involves signaling cascades such as Mitogen-Activated Protein Kinases (MAPKs) or the TOR pathway as a switch for re-directing energy towards defense or growth. In this work, we challenged A. thaliana (wild type, mpk6 or mpk3 mutants, and overexpressing TOR) seedlings with P. aeruginosa PAO1 strains to identify the role of bacterial CDPs in the plant immune response. Results showed that the pre-exposure of these Arabidopsis seedlings to CDPs significantly reduced plant infection of the pathogenic P. aeruginosa PAO1 strains, indicating that plants that over-express AtTOR or lack MPK3/MPK6 protein-kinases are more susceptible to the pathogenic effects. In addition, CDPs induced the GUS activity only in the LOX2::GUS plants, indicative of JA-signaling activation. Our findings indicate that the CDPs are molecules that trigger SA-independent and JA-dependent defense responses in A. thaliana; hence, bacterial CDPs may be considered elicitors of the Arabidopsis immune response to pathogens.
Collapse
Affiliation(s)
- Cristhian Said Solis-Ortiz
- Laboratorio de Biotecnología Molecular de Plantas, Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, 58030, Morelia, Michoacán, Mexico
| | - Javier Gonzalez-Bernal
- Laboratorio de Biotecnología Molecular de Plantas, Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, 58030, Morelia, Michoacán, Mexico
| | - Héctor Antonio Kido-Díaz
- Laboratorio de Biotecnología Molecular de Plantas, Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, 58030, Morelia, Michoacán, Mexico
| | - Cesar Artuto Peña-Uribe
- Laboratorio de Biotecnología Molecular de Plantas, Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, 58030, Morelia, Michoacán, Mexico
| | - Jesús Salvador López-Bucio
- Laboratorio de Biotecnología Molecular de Plantas, Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, 58030, Morelia, Michoacán, Mexico
| | - José López-Bucio
- Laboratorio de Biología del Desarrollo Vegetal, Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, 58030, Morelia, Michoacán, Mexico
| | | | - Ernesto García-Pineda
- Laboratorio de Bioquímica y Biología Molecular de Plantas, Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, 58030, Morelia, Michoacán, Mexico
| | - Javier Villegas
- Laboratorio de Interacción Suelo Planta Microorganismo, Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, 58030, Morelia, Michoacán, Mexico
| | - Jesús Campos-García
- Laboratorio de Biotecnología Microbiana, Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, 58030, Morelia, Michoacán, Mexico.
| | - Homero Reyes de La Cruz
- Laboratorio de Biotecnología Molecular de Plantas, Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, 58030, Morelia, Michoacán, Mexico.
| |
Collapse
|
7
|
Fidalgo da Silva E, Fong J, Roye-Azar A, Nadi A, Drouillard C, Pillon A, Porter LA. Beyond Protein Synthesis; The Multifaceted Roles of Tuberin in Cell Cycle Regulation. Front Cell Dev Biol 2022; 9:806521. [PMID: 35096832 PMCID: PMC8795880 DOI: 10.3389/fcell.2021.806521] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 12/16/2021] [Indexed: 12/13/2022] Open
Abstract
The ability of cells to sense diverse environmental signals, including nutrient availability and conditions of stress, is critical for both prokaryotes and eukaryotes to mount an appropriate physiological response. While there is a great deal known about the different biochemical pathways that can detect and relay information from the environment, how these signals are integrated to control progression through the cell cycle is still an expanding area of research. Over the past three decades the proteins Tuberin, Hamartin and TBC1D7 have emerged as a large protein complex called the Tuberous Sclerosis Complex. This complex can integrate a wide variety of environmental signals to control a host of cell biology events including protein synthesis, cell cycle, protein transport, cell adhesion, autophagy, and cell growth. Worldwide efforts have revealed many molecular pathways which alter Tuberin post-translationally to convey messages to these important pathways, with most of the focus being on the regulation over protein synthesis. Herein we review the literature supporting that the Tuberous Sclerosis Complex plays a critical role in integrating environmental signals with the core cell cycle machinery.
Collapse
Affiliation(s)
| | | | | | | | | | | | - L. A. Porter
- Department of Biomedical Sciences, University of Windsor, Windsor, ON, Canada
| |
Collapse
|
8
|
Halova L, Cobley D, Franz-Wachtel M, Wang T, Morrison KR, Krug K, Nalpas N, Maček B, Hagan IM, Humphrey SJ, Petersen J. A TOR (target of rapamycin) and nutritional phosphoproteome of fission yeast reveals novel targets in networks conserved in humans. Open Biol 2021; 11:200405. [PMID: 33823663 PMCID: PMC8025308 DOI: 10.1098/rsob.200405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/05/2021] [Indexed: 12/21/2022] Open
Abstract
Fluctuations in TOR, AMPK and MAP-kinase signalling maintain cellular homeostasis and coordinate growth and division with environmental context. We have applied quantitative, SILAC mass spectrometry to map TOR and nutrient-controlled signalling in the fission yeast Schizosaccharomyces pombe. Phosphorylation levels at more than 1000 sites were altered following nitrogen stress or Torin1 inhibition of the TORC1 and TORC2 networks that comprise TOR signalling. One hundred and thirty of these sites were regulated by both perturbations, and the majority of these (119) new targets have not previously been linked to either nutritional or TOR control in either yeasts or humans. Elimination of AMPK inhibition of TORC1, by removal of AMPKα (ssp2::ura4+), identified phosphosites where nitrogen stress-induced changes were independent of TOR control. Using a yeast strain with an ATP analogue-sensitized Cdc2 kinase, we excluded sites that were changed as an indirect consequence of mitotic control modulation by nitrogen stress or TOR signalling. Nutritional control of gene expression was reflected in multiple targets in RNA metabolism, while significant modulation of actin cytoskeletal components points to adaptations in morphogenesis and cell integrity networks. Reduced phosphorylation of the MAPKK Byr1, at a site whose human equivalent controls docking between MEK and ERK, prevented sexual differentiation when resources were sparse but not eliminated.
Collapse
Affiliation(s)
- Lenka Halova
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
- Cancer Research UK Manchester Institute, Alderley Park, Macclesfield SK10 4TG, UK
| | - David Cobley
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Mirita Franz-Wachtel
- Proteome Center Tuebingen, University of Tuebingen, Auf der Morgenstelle 15, 72076 Tuebingen, Germany
| | - Tingting Wang
- Flinders Health and Medical Research Institute, Flinders Centre for Innovation in Cancer, Flinders University, Adelaide, South Australia 5042, Australia
| | - Kaitlin R. Morrison
- Flinders Health and Medical Research Institute, Flinders Centre for Innovation in Cancer, Flinders University, Adelaide, South Australia 5042, Australia
| | - Karsten Krug
- Proteome Center Tuebingen, University of Tuebingen, Auf der Morgenstelle 15, 72076 Tuebingen, Germany
| | - Nicolas Nalpas
- Proteome Center Tuebingen, University of Tuebingen, Auf der Morgenstelle 15, 72076 Tuebingen, Germany
| | - Boris Maček
- Proteome Center Tuebingen, University of Tuebingen, Auf der Morgenstelle 15, 72076 Tuebingen, Germany
| | - Iain M. Hagan
- Cancer Research UK Manchester Institute, Alderley Park, Macclesfield SK10 4TG, UK
| | - Sean J. Humphrey
- Charles Perkins Centre, School of Life and Environmental Sciences, The University of Sydney, Camperdown, New South Wales, Australia
| | - Janni Petersen
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
- Flinders Health and Medical Research Institute, Flinders Centre for Innovation in Cancer, Flinders University, Adelaide, South Australia 5042, Australia
- Nutrition and Metabolism, South Australia Health and Medical Research Institute, North Terrace, Adelaide, South Australia 5000, Australia
| |
Collapse
|
9
|
Pataki E, Simhaev L, Engel H, Cohen A, Kupiec M, Weisman R. TOR Complex 2- independent mutations in the regulatory PIF pocket of Gad8AKT1/SGK1 define separate branches of the stress response mechanisms in fission yeast. PLoS Genet 2020; 16:e1009196. [PMID: 33137119 PMCID: PMC7660925 DOI: 10.1371/journal.pgen.1009196] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 11/12/2020] [Accepted: 10/14/2020] [Indexed: 12/12/2022] Open
Abstract
The Target of rapamycin (TOR) protein kinase forms part of TOR complex 1 (TORC1) and TOR complex 2 (TORC2), two multi-subunit protein complexes that regulate growth, proliferation, survival and developmental processes by phosphorylation and activation of AGC-family kinases. In the fission yeast, Schizosaccharomyces pombe, TORC2 and its target, the AGC kinase Gad8 (an orthologue of human AKT or SGK1) are required for viability under stress conditions and for developmental processes in response to starvation cues. In this study, we describe the isolation of gad8 mutant alleles that bypass the requirement for TORC2 and reveal a separation of function of TORC2 and Gad8 under stress conditions. In particular, osmotic and nutritional stress responses appear to form a separate branch from genotoxic stress responses downstream of TORC2-Gad8. Interestingly, TORC2-independent mutations map into the regulatory PIF pocket of Gad8, a highly conserved motif in AGC kinases that regulates substrate binding in PDK1 (phosphoinositide dependent kinase-1) and kinase activity in several AGC kinases. Gad8 activation is thought to require a two-step mechanism, in which phosphorylation by TORC2 allows further phosphorylation and activation by Ksg1 (an orthologue of PDK1). We focus on the Gad8-K263C mutation and demonstrate that it renders the Gad8 kinase activity independent of TORC2 in vitro and independent of the phosphorylation sites of TORC2 in vivo. Molecular dynamics simulations of Gad8-K263C revealed abnormal high flexibility at T387, the phosphorylation site for Ksg1, suggesting a mechanism for the TORC2-independent Gad8 activity. Significantly, the K263 residue is highly conserved in the family of AGC-kinases, which may suggest a general way of keeping their activity in check when acting downstream of TOR complexes. Protein kinases catalyze the transfer of phosphate from high-energy, phosphate-donating molecules, such as ATP, to their substrates. This process is pivotal for regulation of almost any aspect of cellular biology. Many human diseases are associated with aberrant functions of protein kinases due to mutations. Accordingly, there is a growing number of kinase inhibitors that have been approved for clinical use. A better understanding of how protein kinases become active and how their activity is relayed to regulate their cellular functions is much needed for rational design of kinase inhibitors and for their optimal use in the clinic. The AGC-family of protein kinases play key roles in regulating cellular growth, proliferation and survival. In human cells, as well as in the fission yeast, our cellular model system, a subgroup of the AGC kinases is activated by the TOR protein kinases. Here we report the isolation of mutations in the AGC kinase Gad8 (AKT or SGK1 in human) that bypass the requirement for activation by TOR. Analyses of how these mutations affect cellular growth revealed separate branches of stress response mechanisms downstream of Gad8, while computer simulation methods suggested a molecular mechanism that keeps the activity of Gad8 in check.
Collapse
Affiliation(s)
- Emese Pataki
- Department of Natural and Life Sciences, The Open University of Israel, Ra'anana, Israel
| | - Luba Simhaev
- Blavatnik Center for Drug Discovery, Tel Aviv University, Tel Aviv, Israel
| | - Hamutal Engel
- Blavatnik Center for Drug Discovery, Tel Aviv University, Tel Aviv, Israel
| | - Adiel Cohen
- Department of Natural and Life Sciences, The Open University of Israel, Ra'anana, Israel
| | - Martin Kupiec
- The Shmunis School of Biomedicine & Cancer Research, Tel Aviv University, Ramat Aviv, Tel Aviv, Israel
| | - Ronit Weisman
- Department of Natural and Life Sciences, The Open University of Israel, Ra'anana, Israel
- * E-mail:
| |
Collapse
|
10
|
Edreira T, Celador R, Manjón E, Sánchez Y. A novel checkpoint pathway controls actomyosin ring constriction trigger in fission yeast. eLife 2020; 9:59333. [PMID: 33103994 PMCID: PMC7661037 DOI: 10.7554/elife.59333] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 10/24/2020] [Indexed: 12/12/2022] Open
Abstract
In fission yeast, the septation initiation network (SIN) ensures temporal coordination between actomyosin ring (CAR) constriction with membrane ingression and septum synthesis. However, questions remain about CAR regulation under stress conditions. We show that Rgf1p (Rho1p GEF), participates in a delay of cytokinesis under cell wall stress (blankophor, BP). BP did not interfere with CAR assembly or the rate of CAR constriction, but did delay the onset of constriction in the wild type cells but not in the rgf1Δ cells. This delay was also abolished in the absence of Pmk1p, the MAPK of the cell integrity pathway (CIP), leading to premature abscission and a multi-septated phenotype. Moreover, cytokinesis delay correlates with maintained SIN signaling and depends on the SIN to be achieved. Thus, we propose that the CIP participates in a checkpoint, capable of triggering a CAR constriction delay through the SIN pathway to ensure that cytokinesis terminates successfully.
Collapse
Affiliation(s)
- Tomás Edreira
- Instituto de Biología Funcional y Genómica, CSIC/Universidad de Salamanca and Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
| | - Rubén Celador
- Instituto de Biología Funcional y Genómica, CSIC/Universidad de Salamanca and Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
| | - Elvira Manjón
- Instituto de Biología Funcional y Genómica, CSIC/Universidad de Salamanca and Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
| | - Yolanda Sánchez
- Instituto de Biología Funcional y Genómica, CSIC/Universidad de Salamanca and Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
| |
Collapse
|
11
|
Požgajová M, Navrátilová A, Šebová E, Kovár M, Kačániová M. Cadmium-Induced Cell Homeostasis Impairment is Suppressed by the Tor1 Deficiency in Fission Yeast. Int J Mol Sci 2020; 21:ijms21217847. [PMID: 33105893 PMCID: PMC7660220 DOI: 10.3390/ijms21217847] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 10/10/2020] [Accepted: 10/19/2020] [Indexed: 12/16/2022] Open
Abstract
Cadmium has no known physiological function in the body; however, its adverse effects are associated with cancer and many types of organ system damage. Although much has been shown about Cd toxicity, the underlying mechanisms of its responses to the organism remain unclear. In this study, the role of Tor1, a catalytic subunit of the target of rapamycin complex 2 (TORC2), in Cd-mediated effects on cell proliferation, the antioxidant system, morphology, and ionome balance was investigated in the eukaryotic model organism Schizosaccharomyces pombe. Surprisingly, spectrophotometric and biochemical analyses revealed that the growth rate conditions and antioxidant defense mechanisms are considerably better in cells lacking the Tor1 signaling. The malondialdehyde (MDA) content of Tor1-deficient cells upon Cd treatment represents approximately half of the wild-type content. The microscopic determination of the cell morphological parameters indicates the role for Tor1 in cell shape maintenance. The ion content, determined by inductively coupled plasma optical emission spectroscopy (ICP-OES), showed that the Cd uptake potency was markedly lower in Tor1-depleted compared to wild-type cells. Conclusively, we show that the cadmium-mediated cell impairments in the fission yeast significantly depend on the Tor1 signaling. Additionally, the data presented here suggest the yet-undefined role of Tor1 in the transport of ions.
Collapse
Affiliation(s)
- Miroslava Požgajová
- AgroBioTech Research Centre, Slovak University of Agriculture in Nitra, 949 76 Nitra, Slovakia
- Correspondence: ; Tel.: +421-37-641-4919
| | - Alica Navrátilová
- Department of Genetics and Breeding Biology, Faculty of Agrobiology and Food Resources, Slovak University of Agriculture in Nitra, 94976 Nitra, Slovakia;
| | - Eva Šebová
- Institute of Experimental Medicine, Czech Academy of Science, 14220 Prague, Czech Republic;
| | - Marek Kovár
- Department of Plant Physiology, Faculty of Agrobiology and Food Resources, Slovak University of Agriculture in Nitra, 94976 Nitra, Slovakia;
| | - Miroslava Kačániová
- Department of Fruit Science, Viticulture and Enology, Faculty of Horticulture and Landscape Engineering, Slovak University of Agriculture in Nitra, 94976 Nitra, Slovakia;
- Department of Bioenergetics, Food Analysis and Microbiology, Institute of Food Technology and Nutrition, University of Rzeszow, 35-601 Rzeszow, Poland
| |
Collapse
|
12
|
Alao JP, Johansson-Sjölander J, Rallis C, Sunnerhagen P. Caffeine Stabilises Fission Yeast Wee1 in a Rad24-Dependent Manner but Attenuates Its Expression in Response to DNA Damage. Microorganisms 2020; 8:microorganisms8101512. [PMID: 33008060 PMCID: PMC7600152 DOI: 10.3390/microorganisms8101512] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 09/17/2020] [Accepted: 09/24/2020] [Indexed: 12/12/2022] Open
Abstract
The widely consumed neuroactive compound caffeine has generated much interest due to its ability to override the DNA damage and replication checkpoints. Previously Rad3 and its homologues was thought to be the target of caffeine’s inhibitory activity. Later findings indicate that the Target of Rapamycin Complex 1 (TORC1) is the preferred target of caffeine. Effective Cdc2 inhibition requires both the activation of the Wee1 kinase and inhibition of the Cdc25 phosphatase. The TORC1, DNA damage, and environmental stress response pathways all converge on Cdc25 and Wee1. We previously demonstrated that caffeine overrides DNA damage checkpoints by modulating Cdc25 stability. The effect of caffeine on cell cycle progression resembles that of TORC1 inhibition. Furthermore, caffeine activates the Sty1 regulated environmental stress response. Caffeine may thus modulate multiple signalling pathways that regulate Cdc25 and Wee1 levels, localisation and activity. Here we show that the activity of caffeine stabilises both Cdc25 and Wee1. The stabilising effect of caffeine and genotoxic agents on Wee1 was dependent on the Rad24 chaperone. Interestingly, caffeine inhibited the accumulation of Wee1 in response to DNA damage. Caffeine may modulate cell cycle progression through increased Cdc25 activity and Wee1 repression following DNA damage via TORC1 inhibition, as TORC1 inhibition increased DNA damage sensitivity.
Collapse
Affiliation(s)
- John P Alao
- School of Health, Sports and Bioscience, University of East London, Stratford Campus, London E15 4LZ, UK
- Department of Chemistry and Molecular Biology, University of Gothenburg, P.O. Box 462, SE-405 30 Gothenburg, Sweden
| | - Johanna Johansson-Sjölander
- Department of Chemistry and Molecular Biology, University of Gothenburg, P.O. Box 462, SE-405 30 Gothenburg, Sweden
| | - Charalampos Rallis
- School of Health, Sports and Bioscience, University of East London, Stratford Campus, London E15 4LZ, UK
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Per Sunnerhagen
- Department of Chemistry and Molecular Biology, University of Gothenburg, P.O. Box 462, SE-405 30 Gothenburg, Sweden
| |
Collapse
|
13
|
Ghosal A, Sarkar P, Sundaram G. Communication between Cyclin-dependent kinase Cdc2 and the Wis1-Spc1 MAPK pathway determines mitotic timing in Schizosaccharomyces pombe. Biol Open 2020; 9:bio053322. [PMID: 32554481 PMCID: PMC7390630 DOI: 10.1242/bio.053322] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 05/26/2020] [Indexed: 11/20/2022] Open
Abstract
Checkpoint activation and gene expression modulation represent key determinants of cellular survival in adverse conditions. The former is regulated by cyclin-dependent kinases (CDKs) while the latter can be controlled by mitogen-activated protein kinases (MAPKs). Association between cell-cycle progression and MAPK-dependent gene expression exists in cells growing in optimal environments. While MAPK-mediated regulation of the cell cycle is well characterised, the reciprocal influence of mitotic CDK on stress response is not well studied. We present evidence that CDK activity can regulate the extent of MAPK activation in Schizosaccharomyces pombe cells. We show that increasing or decreasing mitotic CDK (Cdc2) activity in S. pombe cells can affect the activation of stress responsive MAPK (Spc1) even in the absence of stress stimuli. Our results indicate that the strong correlation between Cdc2 activity and Spc1 MAPK-activity in S. pombe is important in regulating mitotic timing.This article has an associated First Person interview with the first author of the paper.
Collapse
Affiliation(s)
- Agamani Ghosal
- Department of Biochemistry, University of Calcutta, 35, Ballygunge Circular Road, Kolkata, 700019, WB, India
| | - Priyanka Sarkar
- Department of Biochemistry, University of Calcutta, 35, Ballygunge Circular Road, Kolkata, 700019, WB, India
| | - Geetanjali Sundaram
- Department of Biochemistry, University of Calcutta, 35, Ballygunge Circular Road, Kolkata, 700019, WB, India
| |
Collapse
|
14
|
Rincón AM, Monje-Casas F. A guiding torch at the poles: the multiple roles of spindle microtubule-organizing centers during cell division. Cell Cycle 2020; 19:1405-1421. [PMID: 32401610 DOI: 10.1080/15384101.2020.1754586] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
The spindle constitutes the cellular machinery that enables the segregation of the chromosomes during eukaryotic cell division. The microtubules that form this fascinating and complex genome distribution system emanate from specialized structures located at both its poles and known as microtubule-organizing centers (MTOCs). Beyond their structural function, the spindle MTOCs play fundamental roles in cell cycle control, the activation and functionality of the mitotic checkpoints and during cellular aging. This review highlights the pivotal importance of spindle-associated MTOCs in multiple cellular processes and their central role as key regulatory hubs where diverse intracellular signals are integrated and coordinated to ensure the successful completion of cell division and the maintenance of the replicative lifespan.
Collapse
Affiliation(s)
- Ana M Rincón
- Centro Andaluz de Biología Molecular Y Medicina Regenerativa (CABIMER) / CSIC - Universidad de Sevilla - Universidad Pablo de Olavide , Sevilla, Spain.,Dpto. de Genética / Universidad de Sevilla , Sevilla, Spain
| | - Fernando Monje-Casas
- Centro Andaluz de Biología Molecular Y Medicina Regenerativa (CABIMER) / CSIC - Universidad de Sevilla - Universidad Pablo de Olavide , Sevilla, Spain.,Consejo Superior de Investigaciones Científicas (CSIC) , Sevilla, Spain
| |
Collapse
|
15
|
Nitrogen starvation reveals the mitotic potential of mutants in the S/MAPK pathways. Nat Commun 2020; 11:1973. [PMID: 32332728 PMCID: PMC7181643 DOI: 10.1038/s41467-020-15880-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 03/24/2020] [Indexed: 02/08/2023] Open
Abstract
The genetics of quiescence is an emerging field compared to that of growth, yet both states generate spontaneous mutations and genetic diversity fueling evolution. Reconciling mutation rates in dividing conditions and mutation accumulation as a function of time in non-dividing situations remains a challenge. Nitrogen-starved fission yeast cells reversibly arrest proliferation, are metabolically active and highly resistant to a variety of stresses. Here, we show that mutations in stress- and mitogen-activated protein kinase (S/MAPK) signaling pathways are enriched in aging cultures. Targeted resequencing and competition experiments indicate that these mutants arise in the first month of quiescence and expand clonally during the second month at the expense of the parental population. Reconstitution experiments show that S/MAPK modules mediate the sacrifice of many cells for the benefit of some mutants. These findings suggest that non-dividing conditions promote genetic diversity to generate a social cellular environment prone to kin selection. Nitrogen-starved fission yeast cells survive for weeks without dividing. Here, the authors show that some of these surviving cells accumulate mutations in the stress- and mitogen-activated protein kinase pathways and outcompete their parental cells, which provide nutrients for the mutant cells.
Collapse
|
16
|
Kanou A, Nishimura S, Tabuchi T, Matsuyama A, Yoshida M, Kato T, Kakeya H. Serine catabolism produces ROS, sensitizes cells to actin dysfunction, and suppresses cell growth in fission yeast. J Antibiot (Tokyo) 2020; 73:574-580. [PMID: 32313168 DOI: 10.1038/s41429-020-0305-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 03/12/2020] [Accepted: 03/23/2020] [Indexed: 12/30/2022]
Abstract
Serine is an essential component in organisms as a building block of biomolecules, a precursor of metabolites, an allosteric regulator of an enzyme, etc. This amino acid is thought to be a key metabolite in human diseases including cancers and infectious diseases. To understand the consequence of serine catabolism, we screened natural products to identify a fungal metabolite chaetoglobosin D (ChD) as a specific inhibitor of fission yeast cell growth when cultivated with serine as a sole nitrogen source. ChD targets actin, and actin mutant cells showed severe growth defect on serine medium. ROS accumulated in cells when cultivated in serine medium, while actin mutant cells showed increased sensitivity to oxidative stress. ROS production is a new aspect of serine metabolism, which might be involved in disease progression, and actin could be the drug target for curing serine-dependent symptoms.
Collapse
Affiliation(s)
- Akihiko Kanou
- Department of System Chemotherapy and Molecular Sciences, Division of Bioinformatics and Chemical Genomics, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan
| | - Shinichi Nishimura
- Department of System Chemotherapy and Molecular Sciences, Division of Bioinformatics and Chemical Genomics, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan. .,Department of Biotechnology, The University of Tokyo, Tokyo, 113-8657, Japan. .,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, 113-8657, Japan. .,Chemical Genomics Research Group, RIKEN Center for Sustainable Resource Science, Saitama, 351-0198, Japan.
| | - Toshitsugu Tabuchi
- Department of Biotechnology, The University of Tokyo, Tokyo, 113-8657, Japan
| | - Akihisa Matsuyama
- Department of Biotechnology, The University of Tokyo, Tokyo, 113-8657, Japan.,Chemical Genomics Research Group, RIKEN Center for Sustainable Resource Science, Saitama, 351-0198, Japan
| | - Minoru Yoshida
- Department of Biotechnology, The University of Tokyo, Tokyo, 113-8657, Japan.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, 113-8657, Japan.,Chemical Genomics Research Group, RIKEN Center for Sustainable Resource Science, Saitama, 351-0198, Japan
| | - Taira Kato
- Research & Development Division, MicroBiopharm Japan Co., Ltd., 156 Nakagawara, Kiyosu-shi, Aichi, 452-0915, Japan
| | - Hideaki Kakeya
- Department of System Chemotherapy and Molecular Sciences, Division of Bioinformatics and Chemical Genomics, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan.
| |
Collapse
|
17
|
Ling NXY, Kaczmarek A, Hoque A, Davie E, Ngoei KRW, Morrison KR, Smiles WJ, Forte GM, Wang T, Lie S, Dite TA, Langendorf CG, Scott JW, Oakhill JS, Petersen J. mTORC1 directly inhibits AMPK to promote cell proliferation under nutrient stress. Nat Metab 2020; 2:41-49. [PMID: 31993556 PMCID: PMC6986917 DOI: 10.1038/s42255-019-0157-1] [Citation(s) in RCA: 95] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 12/10/2019] [Indexed: 11/20/2022]
Abstract
Central to cellular metabolism and cell proliferation are highly conserved signalling pathways controlled by mammalian target of rapamycin (mTOR) and AMP-activated protein kinase (AMPK)1,2, dysregulation of which are implicated in pathogenesis of major human diseases such as cancer and type 2 diabetes. AMPK pathways leading to reduced cell proliferation are well established and, in part, act through inhibition of TOR complex-1 (TORC1) activity. Here we demonstrate reciprocal regulation, specifically that TORC1 directly down-regulates AMPK signalling by phosphorylating the evolutionarily conserved residue Ser367 in the fission yeast AMPK catalytic subunit Ssp2, and AMPK α1Ser347/α2Ser345 in the mammalian homologs, which is associated with reduced phosphorylation of activation loop Thr172. Genetic or pharmacological inhibition of TORC1 signalling led to AMPK activation in the absence of increased AMP:ATP ratios; under nutrient stress conditions this was associated with growth limitation in both yeast and human cell cultures. Our findings reveal fundamental, bi-directional regulation between two major metabolic signalling networks and uncover new opportunity for cancer treatment strategies aimed at suppressing cell proliferation in the nutrient-poor tumor microenvironment.
Collapse
Affiliation(s)
- Naomi X Y Ling
- Metabolic Signalling Laboratory, St Vincent's Institute of Medical Research, School of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - Adrian Kaczmarek
- Flinders Centre for Innovation in Cancer, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Ashfaqul Hoque
- Metabolic Signalling Laboratory, St Vincent's Institute of Medical Research, School of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - Elizabeth Davie
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - Kevin R W Ngoei
- Protein Chemistry and Metabolism Unit, St Vincent's Institute of Medical Research, School of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - Kaitlin R Morrison
- Flinders Centre for Innovation in Cancer, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - William J Smiles
- Metabolic Signalling Laboratory, St Vincent's Institute of Medical Research, School of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | | | - Tingting Wang
- Flinders Centre for Innovation in Cancer, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Shervi Lie
- Flinders Centre for Innovation in Cancer, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Toby A Dite
- Metabolic Signalling Laboratory, St Vincent's Institute of Medical Research, School of Medicine, University of Melbourne, Melbourne, Victoria, Australia
- MRC Protein Phosphorylation and Ubiquitylation Unit, James Black Centre, University of Dundee, Dundee, UK
| | - Christopher G Langendorf
- Protein Chemistry and Metabolism Unit, St Vincent's Institute of Medical Research, School of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - John W Scott
- Protein Chemistry and Metabolism Unit, St Vincent's Institute of Medical Research, School of Medicine, University of Melbourne, Melbourne, Victoria, Australia
- Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Victoria, Australia
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Jonathan S Oakhill
- Metabolic Signalling Laboratory, St Vincent's Institute of Medical Research, School of Medicine, University of Melbourne, Melbourne, Victoria, Australia.
- Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Victoria, Australia.
| | - Janni Petersen
- Flinders Centre for Innovation in Cancer, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia.
- Faculty of Life Sciences, University of Manchester, Manchester, UK.
- Nutrition and Metabolism, South Australia Health and Medical Research Institute, Adelaide, South Australia, Australia.
| |
Collapse
|
18
|
Baker K, Gyamfi IA, Mashanov GI, Molloy JE, Geeves MA, Mulvihill DP. TORC2-Gad8-dependent myosin phosphorylation modulates regulation by calcium. eLife 2019; 8:e51150. [PMID: 31566560 PMCID: PMC6802964 DOI: 10.7554/elife.51150] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 09/26/2019] [Indexed: 01/22/2023] Open
Abstract
Cells respond to changes in their environment through signaling networks that modulate cytoskeleton and membrane organization to coordinate cell-cycle progression, polarized cell growth and multicellular development. Here, we define a novel regulatory mechanism by which the motor activity and function of the fission yeast type one myosin, Myo1, is modulated by TORC2-signalling-dependent phosphorylation. Phosphorylation of the conserved serine at position 742 (S742) within the neck region changes both the conformation of the neck region and the interactions between Myo1 and its associating calmodulin light chains. S742 phosphorylation thereby couples the calcium and TOR signaling networks that are involved in the modulation of myosin-1 dynamics to co-ordinate actin polymerization and membrane reorganization at sites of endocytosis and polarised cell growth in response to environmental and cell-cycle cues.
Collapse
Affiliation(s)
- Karen Baker
- School of BiosciencesUniversity of KentCanterburyUnited Kingdom
| | - Irene A Gyamfi
- School of BiosciencesUniversity of KentCanterburyUnited Kingdom
| | | | | | | | | |
Collapse
|
19
|
Jing X, Xie B, Chen L, Zhang N, Jiang Y, Qin H, Wang H, Hao P, Yang S, Li X. Implementation of the CRISPR-Cas13a system in fission yeast and its repurposing for precise RNA editing. Nucleic Acids Res 2019; 46:e90. [PMID: 29860393 PMCID: PMC6125684 DOI: 10.1093/nar/gky433] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 05/08/2018] [Indexed: 12/13/2022] Open
Abstract
In contrast to genome editing, which introduces genetic changes at the DNA level, disrupting or editing gene transcripts provides a distinct approach to perturbing a genetic system, offering benefits complementary to classic genetic approaches. To develop a new toolset for manipulating RNA, we first implemented a member of the type VI CRISPR systems, Cas13a from Leptotrichia shahii (LshCas13a), in Schizosaccharomyces pombe, an important model organism employed by biologists to study key cellular mechanisms conserved from yeast to humans. This approach was shown to knock down targeted endogenous gene transcripts with different efficiencies. Second, we engineered an RNA editing system by tethering an inactive form of LshCas13a (dCas13) to the catalytic domain of human adenosine deaminase acting on RNA type 2 (hADAR2d), which was shown to be programmable with crRNA to target messenger RNAs and precisely edit specific nucleotide residues. We optimized system parameters using a dual-fluorescence reporter and demonstrated the utility of the system in editing randomly selected endogenous gene transcripts. We further used it to restore the transposition of retrotransposon Tf1 mutants in fission yeast, providing a potential novel toolset for retrovirus manipulation and interference.
Collapse
Affiliation(s)
- Xinyun Jing
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Bingran Xie
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Longxian Chen
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Niubing Zhang
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China.,School of Life Sciences, Henan University, Kaifeng 475000, China
| | - Yiyi Jiang
- Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200031, China
| | - Hang Qin
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Hongbing Wang
- Department of Physiology, Michigan State University, East Lansing, Michigan, United States of America
| | - Pei Hao
- Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200031, China
| | - Sheng Yang
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Xuan Li
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| |
Collapse
|
20
|
Candiracci J, Migeot V, Chionh YH, Bauer F, Brochier T, Russell B, Shiozaki K, Dedon P, Hermand D. Reciprocal regulation of TORC signaling and tRNA modifications by Elongator enforces nutrient-dependent cell fate. SCIENCE ADVANCES 2019; 5:eaav0184. [PMID: 31223645 PMCID: PMC6584457 DOI: 10.1126/sciadv.aav0184] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 05/14/2019] [Indexed: 06/09/2023]
Abstract
Nutrient availability has a profound impact on cell fate. Upon nitrogen starvation, wild-type fission yeast cells uncouple cell growth from cell division to generate small, round-shaped cells that are competent for sexual differentiation. The TORC1 (TOR complex 1) and TORC2 complexes exert opposite controls on cell growth and cell differentiation, but little is known about how their activity is coordinated. We show that transfer RNA (tRNA) modifications by Elongator are critical for this regulation by promoting the translation of both key components of TORC2 and repressors of TORC1. We further identified the TORC2 pathway as an activator of Elongator by down-regulating a Gsk3 (glycogen synthase kinase 3)-dependent inhibitory phosphorylation of Elongator. Therefore, a feedback control is operating between TOR complex (TORC) signaling and tRNA modification by Elongator to enforce the advancement of mitosis that precedes cell differentiation.
Collapse
Affiliation(s)
- Julie Candiracci
- URPHYM-GEMO, University of Namur, rue de Bruxelles, 61, Namur 5000, Belgium
| | - Valerie Migeot
- URPHYM-GEMO, University of Namur, rue de Bruxelles, 61, Namur 5000, Belgium
| | - Yok-Hian Chionh
- Singapore–MIT Alliance for Research and Technology Centre (SMART), Center for Life Sciences 05-06, 28 Medical Drive, 117456 Singapore
| | - Fanelie Bauer
- URPHYM-GEMO, University of Namur, rue de Bruxelles, 61, Namur 5000, Belgium
| | - Thomas Brochier
- URPHYM-GEMO, University of Namur, rue de Bruxelles, 61, Namur 5000, Belgium
| | - Brandon Russell
- Massachusetts Institute of Technology, 56-787B77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA
| | - Kazuhiro Shiozaki
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA 95616, USA
| | - Peter Dedon
- Singapore–MIT Alliance for Research and Technology Centre (SMART), Center for Life Sciences 05-06, 28 Medical Drive, 117456 Singapore
- Massachusetts Institute of Technology, 56-787B77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA
| | - Damien Hermand
- URPHYM-GEMO, University of Namur, rue de Bruxelles, 61, Namur 5000, Belgium
| |
Collapse
|
21
|
Ahmad Z, Magyar Z, Bögre L, Papdi C. Cell cycle control by the target of rapamycin signalling pathway in plants. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:2275-2284. [PMID: 30918972 DOI: 10.1093/jxb/erz140] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 03/15/2019] [Indexed: 06/09/2023]
Abstract
Cells need to ensure a sufficient nutrient and energy supply before committing to proliferate. In response to positive mitogenic signals, such as light, sugar availability, and hormones, the target of rapamycin (TOR) signalling pathway promotes cell growth that connects to the entry and passage through the cell division cycle via multiple signalling mechanisms. Here, we summarize current understanding of cell cycle regulation by the RBR-E2F regulatory hub and the DREAM-like complexes, and highlight possible functional relationships between these regulators and TOR signalling. A genetic screen recently uncovered a downstream signalling component to TOR that regulates cell proliferation, YAK1, a member of the dual specificity tyrosine phosphorylation-regulated kinase (DYRK) family. YAK1 activates the plant-specific SIAMESE-RELATED (SMR) cyclin-dependent kinase inhibitors and therefore could be important to regulate both the CDKA-RBR-E2F pathway to control the G1/S transition and the mitotic CDKB1;1 to control the G2/M transition. TOR, as a master regulator of both protein synthesis-driven cell growth and cell proliferation is also central for cell size homeostasis. We conclude the review by briefly highlighting the potential applications of combining TOR and cell cycle knowledge in the context of ensuring future food security.
Collapse
Affiliation(s)
- Zaki Ahmad
- School of Biological Sciences, Bourne Laboratory. Royal Holloway, University of London, Egham, Surrey, UK
| | - Zoltán Magyar
- Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences Szeged, Hungary
| | - László Bögre
- School of Biological Sciences, Bourne Laboratory. Royal Holloway, University of London, Egham, Surrey, UK
| | - Csaba Papdi
- School of Biological Sciences, Bourne Laboratory. Royal Holloway, University of London, Egham, Surrey, UK
| |
Collapse
|
22
|
Forte GM, Davie E, Lie S, Franz-Wachtel M, Ovens AJ, Wang T, Oakhill JS, Maček B, Hagan IM, Petersen J. Import of extracellular ATP in yeast and man modulates AMPK and TORC1 signalling. J Cell Sci 2019; 132:jcs223925. [PMID: 30814334 PMCID: PMC6467490 DOI: 10.1242/jcs.223925] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Accepted: 02/15/2019] [Indexed: 01/31/2023] Open
Abstract
AMP-activated kinase (AMPK) and target of rapamycin (TOR) signalling coordinate cell growth, proliferation, metabolism and cell survival with the nutrient environment of cells. The poor vasculature and nutritional stress experienced by cells in solid tumours raises the question: how do they assimilate sufficient nutrients to survive? Here, we show that human and fission yeast cells import ATP and AMP from their external environment to regulate AMPK and TOR signalling. Exposure of fission yeast (Schizosaccharomyces pombe) and human cells to external AMP impeded cell growth; however, in yeast this restraining impact required AMPK. In contrast, external ATP rescued the growth defect of yeast mutants with reduced TORC1 signalling; furthermore, exogenous ATP transiently enhanced TORC1 signalling in both yeast and human cell lines. Addition of the PANX1 channel inhibitor probenecid blocked ATP import into human cell lines suggesting that this channel may be responsible for both ATP release and uptake in mammals. In light of these findings, it is possible that the higher extracellular ATP concentration reported in solid tumours is both scavenged and recognized as an additional energy source beneficial for cell growth.
Collapse
Affiliation(s)
- Gabriella M Forte
- Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester, M13 9PT, United Kingdom
| | - Elizabeth Davie
- Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester, M13 9PT, United Kingdom
| | - Shervi Lie
- Flinders Centre for Innovation in Cancer, College of Medicine & Public health, Flinders University, Adelaide, SA 5001, Australia
| | - Mirita Franz-Wachtel
- Proteome Center Tuebingen, University of Tuebingen, Auf der Morgenstelle 15, 72076 Tuebingen, Germany
| | - Ashley J Ovens
- Metabolic Signalling Laboratory, St Vincent's Institute of Medical Research, School of Medicine, University of Melbourne, Victoria 3065, Australia
- Mary MacKillop Institute for Health Research, Australian Catholic University, Victoria 3000, Australia
| | - Tingting Wang
- Flinders Centre for Innovation in Cancer, College of Medicine & Public health, Flinders University, Adelaide, SA 5001, Australia
| | - Jonathan S Oakhill
- Metabolic Signalling Laboratory, St Vincent's Institute of Medical Research, School of Medicine, University of Melbourne, Victoria 3065, Australia
- Mary MacKillop Institute for Health Research, Australian Catholic University, Victoria 3000, Australia
| | - Boris Maček
- Proteome Center Tuebingen, University of Tuebingen, Auf der Morgenstelle 15, 72076 Tuebingen, Germany
| | - Iain M Hagan
- Cancer Research UK Manchester institute, Alderley Park, Macclesfield SK10 4TG, United Kingdom
| | - Janni Petersen
- Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester, M13 9PT, United Kingdom
- Flinders Centre for Innovation in Cancer, College of Medicine & Public health, Flinders University, Adelaide, SA 5001, Australia
- South Australia Health and Medical Research Institute, North Terrace, PO Box 11060, Adelaide SA 5000 Australia
| |
Collapse
|
23
|
Lie S, Banks P, Lawless C, Lydall D, Petersen J. The contribution of non-essential Schizosaccharomyces pombe genes to fitness in response to altered nutrient supply and target of rapamycin activity. Open Biol 2019; 8:rsob.180015. [PMID: 29720420 PMCID: PMC5990653 DOI: 10.1098/rsob.180015] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 04/06/2018] [Indexed: 12/12/2022] Open
Abstract
Nutrient fluctuations in the cellular environment promote changes in cell metabolism and growth to adapt cell proliferation accordingly. The target of rapamycin (TOR) signalling network plays a key role in the coordination of growth and cell proliferation with the nutrient environment and, importantly, nutrient limitation reduces TOR complex 1 (TORC1) signalling. We have performed global quantitative fitness profiling of the collection of Schizosaccharomyces pombe strains from which non-essential genes have been deleted. We identified genes that regulate fitness when cells are grown in a nutrient-rich environment compared with minimal environments, with varying nitrogen sources including ammonium, glutamate and proline. In addition, we have performed the first global screen for genes that regulate fitness when both TORC1 and TORC2 signalling is reduced by Torin1. Analysis of genes whose deletions altered fitness when nutrients were limited, or when TOR signalling was compromised, identified a large number of genes that regulate transmembrane transport, transcription and chromatin organization/regulation and vesicle-mediated transport. The ability to tolerate reduced TOR signalling placed demands upon a large number of biological processes including autophagy, mRNA metabolic processing and nucleocytoplasmic transport. Importantly, novel biological processes and all processes known to be regulated by TOR were identified in our screens. In addition, deletion of 62 genes conserved in humans gave rise to strong sensitivity or resistance to Torin1, and 29 of these 62 genes have novel links to TOR signalling. The identification of chromatin and transcriptional regulation, nutritional uptake and transport pathways in this powerful genetic model now paves the way for a molecular understanding of how cells adapt to the chronic and acute fluctuations in nutrient supply that all eukaryotes experience at some stage, and which is a key feature of cancer cells within solid tumours.
Collapse
Affiliation(s)
- Shervi Lie
- Flinders Centre for Innovation in Cancer, College of Medicine & Public Health, Flinders University, Bedford Park, Adelaide, South Australia 5042, Australia
| | - Peter Banks
- High Throughput Screening Facility, Newcastle Biomedicine, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Conor Lawless
- Institute for Cell & Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne NE2 4HH, UK
| | - David Lydall
- Institute for Cell & Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne NE2 4HH, UK
| | - Janni Petersen
- Flinders Centre for Innovation in Cancer, College of Medicine & Public Health, Flinders University, Bedford Park, Adelaide, South Australia 5042, Australia .,South Australia Health and Medical Research Institute, North Terrace, PO Box 11060, Adelaide, South Australia 5000, Australia
| |
Collapse
|
24
|
Sellam A, Chaillot J, Mallick J, Tebbji F, Richard Albert J, Cook MA, Tyers M. The p38/HOG stress-activated protein kinase network couples growth to division in Candida albicans. PLoS Genet 2019; 15:e1008052. [PMID: 30921326 PMCID: PMC6456229 DOI: 10.1371/journal.pgen.1008052] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 04/09/2019] [Accepted: 02/28/2019] [Indexed: 12/26/2022] Open
Abstract
Cell size is a complex trait that responds to developmental and environmental cues. Quantitative size analysis of mutant strain collections disrupted for protein kinases and transcriptional regulators in the pathogenic yeast Candida albicans uncovered 66 genes that altered cell size, few of which overlapped with known size genes in the budding yeast Saccharomyces cerevisiae. A potent size regulator specific to C. albicans was the conserved p38/HOG MAPK module that mediates the osmostress response. Basal HOG activity inhibited the SBF G1/S transcription factor complex in a stress-independent fashion to delay the G1/S transition. The HOG network also governed ribosome biogenesis through the master transcriptional regulator Sfp1. Hog1 bound to the promoters and cognate transcription factors for ribosome biogenesis regulons and interacted genetically with the SBF G1/S machinery, and thereby directly linked cell growth and division. These results illuminate the evolutionary plasticity of size control and identify the HOG module as a nexus of cell cycle and growth regulation.
Collapse
Affiliation(s)
- Adnane Sellam
- Infectious Diseases Research Centre (CRI), CHU de Québec Research Center (CHUQ), Université Laval, Quebec City, QC, Canada
- Department of Microbiology, Infectious Disease and Immunology, Faculty of Medicine, Université Laval, Quebec City, QC, Canada
| | - Julien Chaillot
- Infectious Diseases Research Centre (CRI), CHU de Québec Research Center (CHUQ), Université Laval, Quebec City, QC, Canada
| | - Jaideep Mallick
- Institute for Research in Immunology and Cancer (IRIC), Department of Medicine, Université de Montréal, Montréal, Québec, Canada
| | - Faiza Tebbji
- Infectious Diseases Research Centre (CRI), CHU de Québec Research Center (CHUQ), Université Laval, Quebec City, QC, Canada
| | - Julien Richard Albert
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Michael A. Cook
- Centre for Systems Biology, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada
| | - Mike Tyers
- Institute for Research in Immunology and Cancer (IRIC), Department of Medicine, Université de Montréal, Montréal, Québec, Canada
- Centre for Systems Biology, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada
| |
Collapse
|
25
|
Down-regulation of Cdk1 activity in G1 coordinates the G1/S gene expression programme with genome replication. Curr Genet 2019; 65:685-690. [DOI: 10.1007/s00294-018-00926-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 12/20/2018] [Accepted: 12/22/2018] [Indexed: 02/07/2023]
|
26
|
Gu Y, Oliferenko S. Cellular geometry scaling ensures robust division site positioning. Nat Commun 2019; 10:268. [PMID: 30664646 PMCID: PMC6341079 DOI: 10.1038/s41467-018-08218-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 12/19/2018] [Indexed: 11/16/2022] Open
Abstract
Cells of a specific cell type may divide within a certain size range. Yet, functionally optimal cellular organization is typically maintained across different cell sizes, a phenomenon known as scaling. The mechanisms underlying scaling and its physiological significance remain elusive. Here we approach this problem by interfering with scaling in the rod-shaped fission yeast Schizosaccharomyces japonicus that relies on cellular geometry cues to position the division site. We show that S. japonicus uses the Cdc42 polarity module to adjust its geometry to changes in the cell size. When scaling is prevented resulting in abnormal cellular length-to-width aspect ratio, cells exhibit severe division site placement defects. We further show that despite the generally accepted view, a similar scaling phenomenon can occur in the sister species, Schizosaccharomyces pombe. Our results demonstrate that scaling is required for normal cell function and delineate possible rules for cellular geometry maintenance in populations of proliferating cells. Cells divide within a given size range and can scale across differing cell sizes but mechanisms and function remain unclear. Here the authors show, despite the current dogma of fission yeast maintaining constant width, some fission yeast can scale their width and length, impacting the positioning of the cell division site.
Collapse
Affiliation(s)
- Ying Gu
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.,Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London, SE1 1UL, UK
| | - Snezhana Oliferenko
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK. .,Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London, SE1 1UL, UK.
| |
Collapse
|
27
|
The Tuberin and Cyclin B1 complex functions as a novel G2/M sensor of serum conditions and Akt signaling. PLoS One 2019; 14:e0210612. [PMID: 30629673 PMCID: PMC6328093 DOI: 10.1371/journal.pone.0210612] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 12/30/2018] [Indexed: 11/29/2022] Open
Abstract
A great deal of ground breaking work has determined that the Tuberin and Hamartin Complex function as a negative regulator of protein synthesis and cell cycle progression through G1/S. This is largely attributed to the GTPase activity of Tuberin that indirectly inhibits the mammalian target of rapamycin (mTOR). During times of ample nutrition Tuberin is inhibited by growth factor signaling, including direct phosphorylation by Akt/PKB, allowing for activation of mTOR and subsequent protein synthesis. It is well rationalized that maintaining homeostasis requires communication between cell growth (mTOR signaling) and cell division (cell cycle regulation), however how this occurs mechanistically has not been resolved. This work demonstrates that in the presence of high serum, and/or Akt signaling, direct binding between Tuberin and the G2/M cyclin, Cyclin B1, is stabilized and the rate of mitotic entry is decreased. Importantly, we show that this results in an increase in cell size. We propose that this represents a novel cell cycle checkpoint linking mitotic onset with the nutritional status of the cell to control cell growth.
Collapse
|
28
|
Rubio A, García-Blanco N, Vázquez-Bolado A, Belén Suárez M, Moreno S. Nutritional cell cycle reprogramming reveals that inhibition of Cdk1 is required for proper MBF-dependent transcription. J Cell Sci 2018; 131:jcs.218743. [PMID: 30154212 DOI: 10.1242/jcs.218743] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 08/20/2018] [Indexed: 01/22/2023] Open
Abstract
In nature, cells and in particular unicellular microorganisms are exposed to a variety of nutritional environments. Fission yeast cells cultured in nitrogen-rich media grow fast, divide with a large size and show a short G1 and a long G2. However, when cultured in nitrogen-poor media, they exhibit reduced growth rate and cell size and a long G1 and a short G2. In this study, we compared the phenotypes of cells lacking the highly conserved cyclin-dependent kinase (Cdk) inhibitor Rum1 and the anaphase-promoting complex/cyclosome (APC/C) activator Ste9 in nitrogen-rich and nitrogen-poor media. Rum1 and Ste9 are dispensable for cell division in nitrogen-rich medium. However, in nitrogen-poor medium they are essential for generating a proper wave of MluI cell-cycle box binding factor (MBF)-dependent transcription at the end of G1, which is crucial for promoting a successful S phase. Mutants lacking Rum1 and Ste9 showed premature entry into S phase and a reduced wave of MBF-dependent transcription, leading to replication stress, DNA damage and G2 cell cycle arrest. This work demonstrates how reprogramming the cell cycle by changing the nutritional environment may reveal new roles for cell cycle regulators.
Collapse
Affiliation(s)
- Angela Rubio
- Instituto de Biología Funcional y Genómica, CSIC, University of Salamanca, 37007 Salamanca, Spain.,Department of Microbiology and Genetics, University of Salamanca, 37007 Salamanca. Spain
| | - Natalia García-Blanco
- Instituto de Biología Funcional y Genómica, CSIC, University of Salamanca, 37007 Salamanca, Spain.,Department of Microbiology and Genetics, University of Salamanca, 37007 Salamanca. Spain
| | - Alicia Vázquez-Bolado
- Instituto de Biología Funcional y Genómica, CSIC, University of Salamanca, 37007 Salamanca, Spain.,Department of Microbiology and Genetics, University of Salamanca, 37007 Salamanca. Spain
| | - María Belén Suárez
- Instituto de Biología Funcional y Genómica, CSIC, University of Salamanca, 37007 Salamanca, Spain.,Department of Microbiology and Genetics, University of Salamanca, 37007 Salamanca. Spain
| | - Sergio Moreno
- Instituto de Biología Funcional y Genómica, CSIC, University of Salamanca, 37007 Salamanca, Spain
| |
Collapse
|
29
|
Cohen A, Habib A, Laor D, Yadav S, Kupiec M, Weisman R. TOR complex 2 in fission yeast is required for chromatin-mediated gene silencing and assembly of heterochromatic domains at subtelomeres. J Biol Chem 2018; 293:8138-8150. [PMID: 29632066 DOI: 10.1074/jbc.ra118.002270] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 03/14/2018] [Indexed: 12/21/2022] Open
Abstract
The conserved serine/threonine protein kinase target of rapamycin (TOR) is a major regulator of eukaryotic cellular and organismal growth and a valuable target for drug therapy. TOR forms the core of two evolutionary conserved complexes, TOR complex 1 (TORC1) and TORC2. In the fission yeast Schizosaccharomyces pombe, TORC2 responds to glucose levels and, by activating the protein kinase Gad8 (an orthologue of human AKT), is required for well-regulated cell cycle progression, starvation responses, and cell survival. Here, we report that TORC2-Gad8 is also required for gene silencing and the formation of heterochromatin at the S. pombe mating-type locus and at subtelomeric regions. Deletion of TORC2-Gad8 resulted in loss of the heterochromatic modification of histone 3 lysine 9 dimethylation (H3K9me2) and an increase in euchromatic modifications, including histone 3 lysine 4 trimethylation (H3K4me3) and histone 4 lysine 16 acetylation (H4K16Ac). Accumulation of RNA polymerase II (Pol II) at subtelomeric genes in TORC2-Gad8 mutant cells indicated a defect in silencing at the transcriptional level. Moreover, a concurrent decrease in histone 4 lysine 20 dimethylation (H4K20me2) suggested elevated histone turnover. Loss of gene silencing in cells lacking TORC2-Gad8 is partially suppressed by loss of the anti-silencer Epe1 and fully suppressed by loss of the Pol II-associated Paf1 complex, two chromatin regulators that have been implicated in heterochromatin stability and spreading. Taken together, our findings suggest that TORC2-Gad8 signaling contributes to epigenetic stability at subtelomeric regions and the mating-type locus in S. pombe.
Collapse
Affiliation(s)
- Adiel Cohen
- Department of Natural and Life Sciences, Open University of Israel, University Road 1, 4353701 Ranana, Israel
| | - Aline Habib
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv 69977801, Tel Aviv, Israel
| | - Dana Laor
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv 69977801, Tel Aviv, Israel
| | - Sudhanshu Yadav
- Department of Natural and Life Sciences, Open University of Israel, University Road 1, 4353701 Ranana, Israel
| | - Martin Kupiec
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv 69977801, Tel Aviv, Israel
| | - Ronit Weisman
- Department of Natural and Life Sciences, Open University of Israel, University Road 1, 4353701 Ranana, Israel.
| |
Collapse
|
30
|
Bhola T, Kapuy O, Vinod PK. Computational modelling of meiotic entry and commitment. Sci Rep 2018; 8:180. [PMID: 29317645 PMCID: PMC5760542 DOI: 10.1038/s41598-017-17478-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 11/24/2017] [Indexed: 01/25/2023] Open
Abstract
In response to developmental and environmental conditions, cells exit the mitotic cell cycle and enter the meiosis program to generate haploid gametes from diploid germ cells. Once cells decide to enter the meiosis program they become irreversibly committed to the completion of meiosis irrespective of the presence of cue signals. How meiotic entry and commitment occur due to the dynamics of the regulatory network is not well understood. Therefore, we constructed a mathematical model of the regulatory network that controls the transition from mitosis to meiosis in Schizosaccharomyces pombe. Upon nitrogen starvation, yeast cells exit mitosis and undergo conjugation and meiotic entry. The model includes the regulation of Mei2, an RNA binding protein required for conjugation and meiotic entry, by multiple feedback loops involving Pat1, a kinase that keeps cells in mitosis, and Ste11, a transcription activator required for the sexual differentiation. The model accounts for various experimental observations and demonstrates that the activation of Mei2 is bistable, which ensures the irreversible commitment to meiosis. Further, we show by integrating the meiosis-specific regulation with a cell cycle model, the dynamics of cell cycle exit, G1 arrest and entry into meiosis under nitrogen starvation.
Collapse
Affiliation(s)
- Tanvi Bhola
- Center for Computational Natural Sciences and Bioinformatics, International Institute of Information Technology, Hyderabad, 500032, India
| | - Orsolya Kapuy
- Semmelweis University, Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Budapest, Hungary
| | - P K Vinod
- Center for Computational Natural Sciences and Bioinformatics, International Institute of Information Technology, Hyderabad, 500032, India.
| |
Collapse
|
31
|
Paul M, Ghosal A, Bandyopadhyay S, G P, Selvam U, Rai N, Sundaram G. The fission yeast MAPK Spc1 senses perturbations in Cdc25 and Wee1 activities and targets Rad24 to restore this balance. Yeast 2017; 35:261-271. [PMID: 29065217 DOI: 10.1002/yea.3289] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 10/11/2017] [Accepted: 10/12/2017] [Indexed: 12/15/2022] Open
Abstract
Mitogen-activated protein kinases (MAPKs) play vital roles in multiple cellular processes and represent prominently pursued targets for development of therapeutic regimes. The MAPK Spc1 (p38 homologue) is known to be very important for both mitotic promotion and delay in Schizosaccharomyces pombe. However, the mechanism responsible for mitotic inhibition has remained elusive. Cdc25 (Cdc2 activator) and Wee1 (Cdc2 inhibtor) are important determinants of mitotic timing in all eukaryotes. Our results show that Spc1 can sense the perturbations in the balance of Cdc25 and Wee1 activities in S. pombe and that its function as a mitotic inhibitor is very important for controlling the same. An Spc1-Srk1-Rad24-dependent pathway for mitotic inhibition has been reported earlier.Here we report the presence of an alternative mechanism wherein Spc1 targets the 14-3-3 protein, Rad24, independently of Srk1, leading to relocalization of Cdc25 and mitotic inhibition. Our observations suggest that this pathway can serve as a backup mechanism for Cdc2 inactivation in the absence of Wee1.
Collapse
Affiliation(s)
- Madhurima Paul
- Department of Biochemistry and Centre for Research in Nanoscience and Nanotechnology, University of Calcutta, 35, Ballygunje Circular Road, Kolkata, 700019, WB, India
| | - Agamani Ghosal
- Department of Biochemistry and Centre for Research in Nanoscience and Nanotechnology, University of Calcutta, 35, Ballygunje Circular Road, Kolkata, 700019, WB, India
| | - Sushobhana Bandyopadhyay
- Department of Biochemistry and Centre for Research in Nanoscience and Nanotechnology, University of Calcutta, 35, Ballygunje Circular Road, Kolkata, 700019, WB, India
| | - Prakadeeswari G
- Department of Biochemistry and Centre for Research in Nanoscience and Nanotechnology, University of Calcutta, 35, Ballygunje Circular Road, Kolkata, 700019, WB, India
| | - Upasna Selvam
- Department of Biochemistry and Centre for Research in Nanoscience and Nanotechnology, University of Calcutta, 35, Ballygunje Circular Road, Kolkata, 700019, WB, India
| | - Neeraj Rai
- Department of Biochemistry and Centre for Research in Nanoscience and Nanotechnology, University of Calcutta, 35, Ballygunje Circular Road, Kolkata, 700019, WB, India
| | - Geetanjali Sundaram
- Department of Biochemistry and Centre for Research in Nanoscience and Nanotechnology, University of Calcutta, 35, Ballygunje Circular Road, Kolkata, 700019, WB, India
| |
Collapse
|
32
|
Short B. Centrosome signaling pathways consult on their decision. J Biophys Biochem Cytol 2017. [PMCID: PMC5584200 DOI: 10.1083/jcb.201708080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Study reveals unexpected dialogue between mitotic entrance and exit pathway proteins on yeast spindle pole bodies. Study reveals unexpected dialog between mitotic entrance and exit pathway proteins on yeast spindle pole bodies.
Collapse
|
33
|
Chan KY, Alonso-Nuñez M, Grallert A, Tanaka K, Connolly Y, Smith DL, Hagan IM. Dialogue between centrosomal entrance and exit scaffold pathways regulates mitotic commitment. J Cell Biol 2017; 216:2795-2812. [PMID: 28774892 PMCID: PMC5584178 DOI: 10.1083/jcb.201702172] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 06/20/2017] [Accepted: 06/28/2017] [Indexed: 11/22/2022] Open
Abstract
The fission yeast scaffold molecule Sid4 anchors the septum initiation network to the spindle pole body (SPB, centrosome equivalent) to control mitotic exit events. A second SPB-associated scaffold, Cut12, promotes SPB-associated Cdk1-cyclin B to drive mitotic commitment. Signals emanating from each scaffold have been assumed to operate independently to promote two distinct outcomes. We now find that signals from Sid4 contribute to the Cut12 mitotic commitment switch. Specifically, phosphorylation of Sid4 by NIMAFin1 reduces Sid4 affinity for its SPB anchor, Ppc89, while also enhancing Sid4's affinity for casein kinase 1δ (CK1δ). The resulting phosphorylation of Sid4 by the newly docked CK1δ recruits Chk2Cds1 to Sid4. Chk2Cds1 then expels the Cdk1-cyclin B antagonistic phosphatase Flp1/Clp1 from the SPB. Flp1/Clp1 departure can then support mitotic commitment when Cdk1-cyclin B activation at the SPB is compromised by reduction of Cut12 function. Such integration of signals emanating from neighboring scaffolds shows how centrosomes/SPBs can integrate inputs from multiple pathways to control cell fate.
Collapse
Affiliation(s)
- Kuan Yoow Chan
- Cell Division Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, England, UK
| | - Marisa Alonso-Nuñez
- Cell Division Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, England, UK
| | - Agnes Grallert
- Cell Division Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, England, UK
| | - Kayoko Tanaka
- Cell Division Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, England, UK
| | - Yvonne Connolly
- Biological Mass Spectrometry Facility, Cancer Research UK Manchester Institute, University of Manchester, Manchester, England, UK
| | - Duncan L Smith
- Biological Mass Spectrometry Facility, Cancer Research UK Manchester Institute, University of Manchester, Manchester, England, UK
| | - Iain M Hagan
- Cell Division Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, England, UK
| |
Collapse
|
34
|
Abstract
All organisms can respond to the availability of nutrients by regulating their metabolism, growth, and cell division. Central to the regulation of growth in response to nutrient availability is the target of rapamycin (TOR) signaling that is composed of two structurally distinct complexes: TOR complex 1 (TORC1) and TOR complex 2 (TORC2). The TOR genes were first identified in yeast as target of rapamycin, a natural product of a soil bacterium, which proved beneficial as an immunosuppressive and anticancer drug and is currently being tested for a handful of other pathological conditions including diabetes, neurodegeneration, and age-related diseases. Studies of the TOR pathway unraveled a complex growth-regulating network. TOR regulates nutrient uptake, transcription, protein synthesis and degradation, as well as metabolic pathways, in a coordinated manner that ensures that cells grow or cease growth in response to nutrient availability. The identification of specific signals and mechanisms that stimulate TOR signaling is an active and exciting field of research that has already identified nitrogen and amino acids as key regulators of TORC1 activity. The signals, as well as the cellular functions of TORC2, are far less well understood. Additional open questions in the field concern the relationships between TORC1 and TORC2, as well as the links with other nutrient-responsive pathways. Here I review the main features of TORC1 and TORC2, with a particular focus on yeasts as model organisms.
Collapse
|
35
|
Sánchez-Mir L, Salat-Canela C, Paulo E, Carmona M, Ayté J, Oliva B, Hidalgo E. Phospho-mimicking Atf1 mutants bypass the transcription activating function of the MAP kinase Sty1 of fission yeast. Curr Genet 2017; 64:97-102. [PMID: 28799013 DOI: 10.1007/s00294-017-0730-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 07/31/2017] [Accepted: 08/01/2017] [Indexed: 12/14/2022]
Abstract
Stress-dependent activation of signaling cascades is often mediated by phosphorylation events, but the exact nature and role of these phosphorelays are frequently poorly understood. Here, we review which are the consequences of the stress-dependent phosphorylation of a transcription factor on gene activation. In fission yeast, the MAP kinase Sty1 is activated upon several environmental hazards and promotes cell adaptation and survival, greatly through activation of a gene program mediated by the transcription factor Atf1. Although described decades ago, the role of the phosphorylation of Atf1 by Sty1 is still a matter of debate. We present here a brief review of recent data, obtained through the characterization of several phosphorylation mutant derivatives of Atf1, demonstrating that Atf1 phosphorylation does not stabilize the factor nor stimulates its binding to DNA. Rather, it provides a structural platform of interaction with the transcriptional machinery. Based on these findings, future work will establish how this phosphorylated trans-activation domain promotes the massive gene expression shift allowing cellular adaptation to stress.
Collapse
Affiliation(s)
- Laura Sánchez-Mir
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, C/Dr. Aiguader 88, 08003, Barcelona, Spain
| | - Clàudia Salat-Canela
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, C/Dr. Aiguader 88, 08003, Barcelona, Spain
| | - Esther Paulo
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, C/Dr. Aiguader 88, 08003, Barcelona, Spain.,Department of Physiology, Cardiovascular Research Institute, University of California, San Francisco, 555 Mission Bay Blvd. South, San Francisco, CA, 94158, USA
| | - Mercè Carmona
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, C/Dr. Aiguader 88, 08003, Barcelona, Spain
| | - José Ayté
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, C/Dr. Aiguader 88, 08003, Barcelona, Spain
| | - Baldo Oliva
- Structural Bioinformatics Laboratory (GRIB), Universitat Pompeu Fabra, C/Dr. Aiguader 88, 08003, Barcelona, Spain
| | - Elena Hidalgo
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, C/Dr. Aiguader 88, 08003, Barcelona, Spain.
| |
Collapse
|
36
|
Abstract
The control of cell fate, growth and proliferation in response to nitrogen availability is a tightly controlled process, with the two TOR complexes (TORC1 and TORC2) and their effectors playing a central role. PP2A-B55Pab1 has recently been shown to be a key element in this response in fission yeast, where it regulates cell cycle progression and sexual differentiation. Importantly, a recent study from our group has shown that PP2A-B55Pab1 acts as a mediator between the activities of the two TOR signaling modules, enabling a crosstalk that is required to engage in the differentiation program. In this review, we recapitulate the studies that have led to our current understanding of the interplay between TOR complexes. Moreover, we discuss several aspects of the response to nitrogen availability that still require further attention, and which will be important in the future to fully realize the implications of phosphatase activity in the context of TOR signaling.
Collapse
Affiliation(s)
- Ruth Martín
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, Gaustadalleen 21, 0349, Oslo, Norway
| | - Sandra Lopez-Aviles
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, Gaustadalleen 21, 0349, Oslo, Norway.
| |
Collapse
|
37
|
Abstract
Cell size is amenable by genetic and environmental factors. The highly conserved nutrient-responsive Target of Rapamycin (TOR) signaling pathway regulates cellular metabolic status and growth in response to numerous inputs. Timing and duration of TOR pathway activity is pivotal for both cell mass built up as well as cell cycle progression and is controlled and fine-tuned by the abundance and quality of nutrients, hormonal signals, growth factors, stress, and oxygen. TOR kinases function within two functionally and structurally discrete multiprotein complexes, TORC1 and TORC2, that are implicated in temporal and spatial control of cell size and growth respectively; however, recent data indicate that such functional distinctions are much more complex. Here, we briefly review roles of the two complexes in cellular growth and cytoarchitecture in various experimental model systems.
Collapse
Affiliation(s)
- Suam Gonzalez
- School of Health, Sport and Bioscience, University of East LondonLondon, United Kingdom
| | - Charalampos Rallis
- School of Health, Sport and Bioscience, University of East LondonLondon, United Kingdom
| |
Collapse
|
38
|
Cell-size dependent progression of the cell cycle creates homeostasis and flexibility of plant cell size. Nat Commun 2017; 8:15060. [PMID: 28447614 PMCID: PMC5414177 DOI: 10.1038/ncomms15060] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 02/23/2017] [Indexed: 11/09/2022] Open
Abstract
Mean cell size at division is generally constant for specific conditions and cell types, but the mechanisms coupling cell growth and cell cycle control with cell size regulation are poorly understood in intact tissues. Here we show that the continuously dividing fields of cells within the shoot apical meristem of Arabidopsis show dynamic regulation of mean cell size dependent on developmental stage, genotype and environmental signals. We show cell size at division and cell cycle length is effectively predicted using a two-stage cell cycle model linking cell growth and two sequential cyclin dependent kinase (CDK) activities, and experimental results concur in showing that progression through both G1/S and G2/M is size dependent. This work shows that cell-autonomous co-ordination of cell growth and cell division previously observed in unicellular organisms also exists in intact plant tissues, and that cell size may be an emergent rather than directly determined property of cells.
Collapse
|
39
|
Cobley D, Hálová L, Schauries M, Kaczmarek A, Franz-Wachtel M, Du W, Krug K, Maček B, Petersen J. Ste12/Fab1 phosphatidylinositol-3-phosphate 5-kinase is required for nitrogen-regulated mitotic commitment and cell size control. PLoS One 2017; 12:e0172740. [PMID: 28273166 PMCID: PMC5342193 DOI: 10.1371/journal.pone.0172740] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 02/08/2017] [Indexed: 11/18/2022] Open
Abstract
Tight coupling of cell growth and cell cycle progression enable cells to adjust their rate of division, and therefore size, to the demands of proliferation in varying nutritional environments. Nutrient stress promotes inhibition of Target Of Rapamycin Complex 1 (TORC1) activity. In fission yeast, reduced TORC1 activity advances mitotic onset and switches growth to a sustained proliferation at reduced cell size. A screen for mutants, that failed to advance mitosis upon nitrogen stress, identified a mutant in the PIKFYVE 1-phosphatidylinositol-3-phosphate 5-kinase fission yeast homolog Ste12. Ste12PIKFYVE deficient mutants were unable to advance the cell cycle to reduce cell size after a nitrogen downshift to poor nitrogen (proline) growth conditions. While it is well established that PI(3,5)P2 signalling is required for autophagy and that Ste12PIKFYVE mutants have enlarged vacuoles (yeast lysosomes), neither a block to autophagy or mutants that independently have enlarged vacuoles had any impact upon nitrogen control of mitotic commitment. The addition of rapamycin to Ste12PIKFYVE deficient mutants reduced cell size at division to suggest that Ste12PIKFYVE possibly functions upstream of TORC1. ste12 mutants display increased Torin1 (TOR inhibitor) sensitivity. However, no major impact on TORC1 or TORC2 activity was observed in the ste12 deficient mutants. In summary, Ste12PIKFYVE is required for nitrogen-stress mediated advancement of mitosis to reduce cell size at division.
Collapse
Affiliation(s)
- David Cobley
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester, M13 9PT, United Kingdom
| | - Lenka Hálová
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester, M13 9PT, United Kingdom
| | - Marie Schauries
- Flinders Centre for Innovation in Cancer, School of Medicine, Flinders University, Adelaide, SA, Australia
| | - Adrian Kaczmarek
- Flinders Centre for Innovation in Cancer, School of Medicine, Flinders University, Adelaide, SA, Australia
| | | | - Wei Du
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester, M13 9PT, United Kingdom
| | - Karsten Krug
- Proteome Center Tübingen, Auf der Morgenstelle, Tuebingen, Germany
| | - Boris Maček
- Proteome Center Tübingen, Auf der Morgenstelle, Tuebingen, Germany
| | - Janni Petersen
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester, M13 9PT, United Kingdom
- Flinders Centre for Innovation in Cancer, School of Medicine, Flinders University, Adelaide, SA, Australia
- South Australia Health and Medical Research Institute, North Terrace, Adelaide SA Australia
- * E-mail:
| |
Collapse
|
40
|
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.
Collapse
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
| |
Collapse
|
41
|
Abstract
Schizosaccharomyces pombe is a good model to study cell-size control. These cells integrate size information into cell cycle controls at both the G1/S and G2/M transitions, although the primary control operates at the entry into mitosis. At G2/M there is both a size threshold, demonstrated by the fact that cells divide when they reach 14 μm in length, and also correction around this threshold, evident from the narrow distribution of sizes within a population. This latter property is referred to as size homeostasis. It has been argued that a population of cells accumulating mass in a linear fashion will have size homeostasis in the absence of size control, if cycle time is controlled by a fixed timer. Because fission yeast cells do not grow in a simple linear fashion, they require a size-sensing mechanism. However, current models do not fully describe all aspects of this control, especially the coordination of cell size with ploidy.
Collapse
Affiliation(s)
- Elizabeth Wood
- Cell Cycle Laboratory, The Francis Crick Institute, London WC2A 3LY, United Kingdom;
| | | |
Collapse
|
42
|
Weng Ng WT, Shin JS, Roberts TL, Wang B, Lee CS. Molecular interactions of polo-like kinase 1 in human cancers. J Clin Pathol 2016; 69:557-62. [PMID: 26941182 DOI: 10.1136/jclinpath-2016-203656] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Accepted: 02/09/2016] [Indexed: 01/22/2023]
Abstract
Polo-like kinase 1 (PLK1) is an essential protein in communicating cell-cycle progression and DNA damage. Overexpression of PLK1 has been validated as a marker for poor prognosis in many cancers. PLK1 knockdown decreases the survival of cancer cells. PLK1 is therefore an attractive target for anticancer treatments. Several inhibitors have been developed, and some have been clinically tested to show additive effects with conventional therapies. Upstream regulation of PLK1 involves multiple interactions of proteins such as FoxM1, E2F and p21. Other cancer-related proteins such as pRB and p53 also indirectly influence PLK1 expression. With the high mutation rates of these genes seen in cancers, they may be associated with PLK1 deregulation. This raises the question of whether PLK1 overexpression is a cause or a consequence of oncogenesis. In addition, hypomethylation of the CpG island of the PLK1 promoter region contributes to its upregulation. PLK1 expression can be affected by many factors; thus, it is possible that PLK1 deregulation in each individual patient tumours could be due to different underlying mechanisms.
Collapse
Affiliation(s)
- Wayne Tiong Weng Ng
- Discipline of Pathology, School of Medicine, Western Sydney University, Sydney, Australia Centre for Oncology Education and Research Translation (CONCERT), Ingham Institute for Applied Medical Research, Sydney, Australia Cancer Pathology and Cell Biology Laboratory, Ingham Institute for Applied Medical Research, Sydney, Australia
| | - Joo-Shik Shin
- Discipline of Pathology, School of Medicine, Western Sydney University, Sydney, Australia Centre for Oncology Education and Research Translation (CONCERT), Ingham Institute for Applied Medical Research, Sydney, Australia Cancer Pathology and Cell Biology Laboratory, Ingham Institute for Applied Medical Research, Sydney, Australia Molecular Medicine Research Group, School of Medicine, Western Sydney University, Sydney, Australia Department of Anatomical Pathology, Liverpool Hospital, Sydney, Australia
| | - Tara Laurine Roberts
- Centre for Oncology Education and Research Translation (CONCERT), Ingham Institute for Applied Medical Research, Sydney, Australia Molecular Medicine Research Group, School of Medicine, Western Sydney University, Sydney, Australia
| | - Bin Wang
- Discipline of Pathology, School of Medicine, Western Sydney University, Sydney, Australia Centre for Oncology Education and Research Translation (CONCERT), Ingham Institute for Applied Medical Research, Sydney, Australia South Western Sydney Clinical School, University of New South Wales, Sydney, Australia
| | - Cheok Soon Lee
- Discipline of Pathology, School of Medicine, Western Sydney University, Sydney, Australia Centre for Oncology Education and Research Translation (CONCERT), Ingham Institute for Applied Medical Research, Sydney, Australia Cancer Pathology and Cell Biology Laboratory, Ingham Institute for Applied Medical Research, Sydney, Australia Molecular Medicine Research Group, School of Medicine, Western Sydney University, Sydney, Australia Department of Anatomical Pathology, Liverpool Hospital, Sydney, Australia South Western Sydney Clinical School, University of New South Wales, Sydney, Australia Cancer Pathology, Bosch Institute, University of Sydney, Sydney, Australia
| |
Collapse
|
43
|
Abstract
Here, we summarize the composition and uses of Schizosaccharomyces pombe media and discuss key issues for consideration in the generation of S. pombe cultures. We discuss the concept of "culture memory," in which the growth state and stress experienced by a strain during storage, propagation, and starter culture preparation can alter experimental outcomes at later stages. We also describe the triggers that are widely used to manipulate signaling through the environment sensing pathways.
Collapse
Affiliation(s)
- Janni Petersen
- Flinders University, Flinders Centre for Innovation in Cancer, School of Medicine, FMST, Bedford Park, SA 5042, Adelaide Australia
| | - Paul Russell
- Department of Cell and Molecular Biology. The Scripps Research Institute 10550 N. Torrey Pines Road, MB3, La Jolla, CA 92037 – USA
| |
Collapse
|
44
|
Cohen A, Kupiec M, Weisman R. Gad8 Protein Is Found in the Nucleus Where It Interacts with the MluI Cell Cycle Box-binding Factor (MBF) Transcriptional Complex to Regulate the Response to DNA Replication Stress. J Biol Chem 2016; 291:9371-81. [PMID: 26912660 DOI: 10.1074/jbc.m115.705251] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Indexed: 12/31/2022] Open
Abstract
The target of rapamycin (TOR) kinase is found at the core of two evolutionarily conserved complexes known as TOR complexes 1 and 2 (TORC1 and TORC2). In fission yeast, TORC2 is dispensable for proliferation under optimal growth conditions but is required for starvation and stress responses. We have previously reported that loss of function of TORC2 renders cells highly sensitive to DNA replication stress; however, the mechanism underlying this sensitivity is unknown. TORC2 has one known direct substrate, the kinase Gad8, which is related to AKT in human cells. Here we show that both TORC2 and its substrate Gad8 are found in the nucleus and are bound to the chromatin. We also demonstrate that Gad8 physically interacts with the MluI cell cycle box-binding factor (MBF) transcription complex that regulates the G1/S progression and the response to DNA stress. In mutant cells lacking TORC2 or Gad8, the binding of the MBF complex to its cognate promoters is compromised, and the induction of MBF target genes in response to DNA replication stress is reduced. Consistently, the protein levels of Cdt2 and Cig2, two MBF target genes, are reduced in the absence of TORC2-Gad8 signaling. Taken together, our findings highlight critical functions of TORC2 in the nucleus and suggest a role in surviving DNA replication stress via transcriptional regulation of MBF target genes.
Collapse
Affiliation(s)
- Adiel Cohen
- From the Department of Natural and Life Sciences, The Open University of Israel, University Road 1, 4353701 Raanana, Israel and
| | - Martin Kupiec
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Ronit Weisman
- From the Department of Natural and Life Sciences, The Open University of Israel, University Road 1, 4353701 Raanana, Israel and
| |
Collapse
|
45
|
Masuda F, Ishii M, Mori A, Uehara L, Yanagida M, Takeda K, Saitoh S. Glucose restriction induces transient G2 cell cycle arrest extending cellular chronological lifespan. Sci Rep 2016; 6:19629. [PMID: 26804466 PMCID: PMC4726166 DOI: 10.1038/srep19629] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 12/16/2015] [Indexed: 01/15/2023] Open
Abstract
While glucose is the fundamental source of energy in most eukaryotes, it is not always abundantly available in natural environments, including within the human body. Eukaryotic cells are therefore thought to possess adaptive mechanisms to survive glucose-limited conditions, which remain unclear. Here, we report a novel mechanism regulating cell cycle progression in response to abrupt changes in extracellular glucose concentration. Upon reduction of glucose in the medium, wild-type fission yeast cells undergo transient arrest specifically at G2 phase. This cell cycle arrest is dependent on the Wee1 tyrosine kinase inhibiting the key cell cycle regulator, CDK1/Cdc2. Mutant cells lacking Wee1 are not arrested at G2 upon glucose limitation and lose viability faster than the wild-type cells under glucose-depleted quiescent conditions, suggesting that this cell cycle arrest is required for extension of chronological lifespan. Our findings indicate the presence of a novel cell cycle checkpoint monitoring glucose availability, which may be a good molecular target for cancer therapy.
Collapse
Affiliation(s)
- Fumie Masuda
- Institute of Life Science, Kurume University, Hyakunen-Khoen 1-1, Kurume, Fukuoka 839-0864, Japan
| | - Mahiro Ishii
- Department of Biology, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Higashinada-ku, Kobe 658-8501, Japan
| | - Ayaka Mori
- Okinawa Institute of Science and Technology Graduate School, Tancha 1919-1, Onna, Okinawa 904-0495, Japan
| | - Lisa Uehara
- Okinawa Institute of Science and Technology Graduate School, Tancha 1919-1, Onna, Okinawa 904-0495, Japan
| | - Mitsuhiro Yanagida
- Okinawa Institute of Science and Technology Graduate School, Tancha 1919-1, Onna, Okinawa 904-0495, Japan
| | - Kojiro Takeda
- Department of Biology, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Higashinada-ku, Kobe 658-8501, Japan.,Institute for Integrative Neurobiology, Konan University, 8-9-1 Okamoto, Higashinada-ku, Kobe 658-8501, Japan
| | - Shigeaki Saitoh
- Institute of Life Science, Kurume University, Hyakunen-Khoen 1-1, Kurume, Fukuoka 839-0864, Japan
| |
Collapse
|
46
|
Chica N, Rozalén AE, Pérez-Hidalgo L, Rubio A, Novak B, Moreno S. Nutritional Control of Cell Size by the Greatwall-Endosulfine-PP2A·B55 Pathway. Curr Biol 2016; 26:319-30. [PMID: 26776736 DOI: 10.1016/j.cub.2015.12.035] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 10/20/2015] [Accepted: 12/09/2015] [Indexed: 02/08/2023]
Abstract
Proliferating cells adjust their cell size depending on the nutritional environment. Cells are large in rich media and small in poor media. This physiological response has been demonstrated in both unicellular and multicellular organisms. Here we show that the greatwall-endosulfine (Ppk18-Igo1 in fission yeast) pathway couples the nutritional environment to the cell-cycle machinery by regulating the activity of PP2A·B55. In the presence of nutrients, greatwall (Ppk18) protein kinase is inhibited by TORC1 and PP2A·B55 is active. High levels of PP2A·B55 prevent the activation of mitotic Cdk1·Cyclin B, and cells increase in size in G2 before they undergo mitosis. When nutrients are limiting, TORC1 activity falls off, and the activation of greatwall (Ppk18) leads to the phosphorylation of endosulfine (Igo1) and inhibition of PP2A·B55, which in turn allows full activation of Cdk1·CyclinB and entry into mitosis with a smaller cell size. Given the conservation of this pathway, it is reasonable to assume that this mechanism operates in higher eukaryotes, as well.
Collapse
Affiliation(s)
- Nathalia Chica
- Instituto de Biología Funcional y Genómica, CSIC/University of Salamanca, 37007 Salamanca, Spain
| | - Ana Elisa Rozalén
- Instituto de Biología Funcional y Genómica, CSIC/University of Salamanca, 37007 Salamanca, Spain
| | - Livia Pérez-Hidalgo
- Instituto de Biología Funcional y Genómica, CSIC/University of Salamanca, 37007 Salamanca, Spain
| | - Angela Rubio
- Instituto de Biología Funcional y Genómica, CSIC/University of Salamanca, 37007 Salamanca, Spain
| | - Bela Novak
- Oxford Centre for Integrative Systems Biology, Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Sergio Moreno
- Instituto de Biología Funcional y Genómica, CSIC/University of Salamanca, 37007 Salamanca, Spain.
| |
Collapse
|
47
|
Kelkar M, Martin SG. PKA antagonizes CLASP-dependent microtubule stabilization to re-localize Pom1 and buffer cell size upon glucose limitation. Nat Commun 2015; 6:8445. [PMID: 26443240 PMCID: PMC4618306 DOI: 10.1038/ncomms9445] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 08/21/2015] [Indexed: 01/28/2023] Open
Abstract
Cells couple growth with division and regulate size in response to nutrient availability. In rod-shaped fission yeast, cell-size control occurs at mitotic commitment. An important regulator is the DYRK-family kinase Pom1, which forms gradients from cell poles and inhibits the mitotic activator Cdr2, itself localized at the medial cortex. Where and when Pom1 modulates Cdr2 activity is unclear as Pom1 medial cortical levels remain constant during cell elongation. Here we show that Pom1 re-localizes to cell sides upon environmental glucose limitation, where it strongly delays mitosis. This re-localization is caused by severe microtubule destabilization upon glucose starvation, with microtubules undergoing catastrophe and depositing the Pom1 gradient nucleator Tea4 at cell sides. Microtubule destabilization requires PKA/Pka1 activity, which negatively regulates the microtubule rescue factor CLASP/Cls1/Peg1, reducing CLASP's ability to stabilize microtubules. Thus, PKA signalling tunes CLASP's activity to promote Pom1 cell side localization and buffer cell size upon glucose starvation.
Collapse
Affiliation(s)
- Manasi Kelkar
- Department of Fundamental Microbiology, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland
| | - Sophie G Martin
- Department of Fundamental Microbiology, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland
| |
Collapse
|
48
|
Hoffman CS, Wood V, Fantes PA. An Ancient Yeast for Young Geneticists: A Primer on the Schizosaccharomyces pombe Model System. Genetics 2015; 201:403-23. [PMID: 26447128 PMCID: PMC4596657 DOI: 10.1534/genetics.115.181503] [Citation(s) in RCA: 150] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The fission yeast Schizosaccharomyces pombe is an important model organism for the study of eukaryotic molecular and cellular biology. Studies of S. pombe, together with studies of its distant cousin, Saccharomyces cerevisiae, have led to the discovery of genes involved in fundamental mechanisms of transcription, translation, DNA replication, cell cycle control, and signal transduction, to name but a few processes. However, since the divergence of the two species approximately 350 million years ago, S. pombe appears to have evolved less rapidly than S. cerevisiae so that it retains more characteristics of the common ancient yeast ancestor, causing it to share more features with metazoan cells. This Primer introduces S. pombe by describing the yeast itself, providing a brief description of the origins of fission yeast research, and illustrating some genetic and bioinformatics tools used to study protein function in fission yeast. In addition, a section on some key differences between S. pombe and S. cerevisiae is included for readers with some familiarity with budding yeast research but who may have an interest in developing research projects using S. pombe.
Collapse
Affiliation(s)
- Charles S Hoffman
- Biology Department, Boston College, Chestnut Hill, Massachusetts 02467
| | - Valerie Wood
- Cambridge Systems Biology Centre and Department of Biochemistry, University of Cambridge, CB2 1GA Cambridge, United Kingdom
| | - Peter A Fantes
- School of Biological Sciences, College of Science and Engineering, University of Edinburgh EH9 3JR Edinburgh, United Kingdom
| |
Collapse
|
49
|
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.
Collapse
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
| |
Collapse
|
50
|
TORC1 Regulates Developmental Responses to Nitrogen Stress via Regulation of the GATA Transcription Factor Gaf1. mBio 2015; 6:e00959. [PMID: 26152587 PMCID: PMC4488950 DOI: 10.1128/mbio.00959-15] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The TOR (target of rapamycin [sirolimus]) is a universally conserved kinase that couples nutrient availability to cell growth. TOR complex 1 (TORC1) in Schizosaccharomyces pombe positively regulates growth in response to nitrogen availability while suppressing cellular responses to nitrogen stress. Here we report the identification of the GATA transcription factor Gaf1 as a positive regulator of the nitrogen stress-induced gene isp7+, via three canonical GATA motifs. We show that under nitrogen-rich conditions, TORC1 positively regulates the phosphorylation and cytoplasmic retention of Gaf1 via the PP2A-like phosphatase Ppe1. Under nitrogen stress conditions when TORC1 is inactivated, Gaf1 becomes dephosphorylated and enters the nucleus. Gaf1 was recently shown to negatively regulate the transcription induction of ste11+, a major regulator of sexual development. Our findings support a model of a two-faceted role of Gaf1 during nitrogen stress. Gaf1 positively regulates genes that are induced early in the response to nitrogen stress, while inhibiting later responses, such as sexual development. Taking these results together, we identify Gaf1 as a novel target for TORC1 signaling and a step-like mechanism to modulate the nitrogen stress response. TOR complex 1 (TORC1) is an evolutionary conserved protein complex that positively regulates growth and proliferation, while inhibiting starvation responses. In fission yeast, the activity of TORC1 is downregulated in response to nitrogen starvation, and cells reprogram their transcriptional profile and prepare for sexual development. We identify Gaf1, a GATA-like transcription factor that regulates transcription and sexual development in response to starvation, as a downstream target for TORC1 signaling. Under nitrogen-rich conditions, TORC1 positively regulates the phosphorylation and cytoplasmic retention of Gaf1 via the PP2A-like phosphatase Ppe1. Under nitrogen stress conditions when TORC1 is inactivated, Gaf1 becomes dephosphorylated and enters the nucleus. Budding yeast TORC1 regulates GATA transcription factors via the phosphatase Sit4, a structural homologue of Ppe1. Thus, the TORC1-GATA transcription module appears to be conserved in evolution and may also be found in higher eukaryotes.
Collapse
|