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Kundert P, Shaulsky G. Cellular allorecognition and its roles in Dictyostelium development and social evolution. THE INTERNATIONAL JOURNAL OF DEVELOPMENTAL BIOLOGY 2019; 63:383-393. [PMID: 31840777 PMCID: PMC6919275 DOI: 10.1387/ijdb.190239gs] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The social amoeba Dictyostelium discoideum is a tractable model organism to study cellular allorecognition, which is the ability of a cell to distinguish itself and its genetically similar relatives from more distantly related organisms. Cellular allorecognition is ubiquitous across the tree of life and affects many biological processes. Depending on the biological context, these versatile systems operate both within and between individual organisms, and both promote and constrain functional heterogeneity. Some of the most notable allorecognition systems mediate neural self-avoidance in flies and adaptive immunity in vertebrates. D. discoideum's allorecognition system shares several structures and functions with other allorecognition systems. Structurally, its key regulators reside at a single genomic locus that encodes two highly polymorphic proteins, a transmembrane ligand called TgrC1 and its receptor TgrB1. These proteins exhibit isoform-specific, heterophilic binding across cells. Functionally, this interaction determines the extent to which co-developing D. discoideum strains co-aggregate or segregate during the aggregation phase of multicellular development. The allorecognition system thus affects both development and social evolution, as available evidence suggests that the threat of developmental cheating represents a primary selective force acting on it. Other significant characteristics that may inform the study of allorecognition in general include that D. discoideum's allorecognition system is a continuous and inclusive trait, it is pleiotropic, and it is temporally regulated.
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Affiliation(s)
- Peter Kundert
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
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2
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Gudipaty SA, Conner CM, Rosenblatt J, Montell DJ. Unconventional Ways to Live and Die: Cell Death and Survival in Development, Homeostasis, and Disease. Annu Rev Cell Dev Biol 2018; 34:311-332. [PMID: 30089222 DOI: 10.1146/annurev-cellbio-100616-060748] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Balancing cell death and survival is essential for normal development and homeostasis and for preventing diseases, especially cancer. Conventional cell death pathways include apoptosis, a form of programmed cell death controlled by a well-defined biochemical pathway, and necrosis, the lysis of acutely injured cells. New types of regulated cell death include necroptosis, pyroptosis, ferroptosis, phagoptosis, and entosis. Autophagy can promote survival or can cause death. Newly described processes of anastasis and resuscitation show that, remarkably, cells can recover from the brink of apoptosis or necroptosis. Important new work shows that epithelia achieve homeostasis by extruding excess cells, which then die by anoikis due to loss of survival signals. This mechanically regulated process both maintains barrier function as cells die and matches rates of proliferation and death. In this review, we describe these unconventional ways in which cells have evolved to die or survive, as well as the contributions that these processes make to homeostasis and cancer.
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Affiliation(s)
- Swapna A Gudipaty
- Department of Oncological Sciences and Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah 84112, USA
| | - Christopher M Conner
- Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, California 93106, USA;
| | - Jody Rosenblatt
- Department of Oncological Sciences and Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah 84112, USA
| | - Denise J Montell
- Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, California 93106, USA;
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3
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Cramer LP, Kay RR, Zatulovskiy E. Repellent and Attractant Guidance Cues Initiate Cell Migration by Distinct Rear-Driven and Front-Driven Cytoskeletal Mechanisms. Curr Biol 2018. [PMID: 29526589 PMCID: PMC5863766 DOI: 10.1016/j.cub.2018.02.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Attractive and repulsive cell guidance is essential for animal life and important in disease. Cell migration toward attractants dominates studies [1, 2, 3, 4, 5, 6, 7, 8], but migration away from repellents is important in biology yet relatively little studied [5, 9, 10]. It is widely held that cells initiate migration by protrusion of their front [11, 12, 13, 14, 15], yet this has not been explicitly tested for cell guidance because cell margin displacement at opposite ends of the cell has not been distinguished for any cue. We argue that protrusion of the front, retraction of the rear, or both together could in principle break cell symmetry and start migration in response to guidance cues [16]. Here, we find in the Dictyostelium model [6] that an attractant—cAMP—breaks symmetry by causing protrusion of the front of the cell, whereas its repellent analog—8CPT—breaks symmetry by causing retraction of the rear. Protrusion of the front of these cells in response to cAMP starts with local actin filament assembly, while the delayed retraction of the rear is independent of both myosin II polarization and of motor-based contractility. On the contrary, myosin II accumulates locally in the rear of the cell in response to 8CPT, anticipating retraction and required for it, while local actin assembly is delayed and couples to delayed protrusion at the front. These data reveal an important new concept in the understanding of cell guidance. In attractant, cell front protrusion breaks cell symmetry and starts migration In repellent, cell rear retraction breaks cell symmetry and starts migration Myosin II motor is not required for front-driven migration toward attractant Biased myosin II motor contractility drives rear-driven migration away from repellent
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Affiliation(s)
- Louise P Cramer
- Laboratory of Molecular Cell Biology and Department of Cell and Developmental Biology, Faculty Life Science, UCL, Gower Street, London WC1E 6BT, England, UK.
| | - Robert R Kay
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, England, UK
| | - Evgeny Zatulovskiy
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, England, UK
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4
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Golstein P. Conserved nucleolar stress at the onset of cell death. FEBS J 2017; 284:3791-3800. [DOI: 10.1111/febs.14095] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 03/31/2017] [Accepted: 04/26/2017] [Indexed: 01/19/2023]
Affiliation(s)
- Pierre Golstein
- Centre d'Immunologie de Marseille‐Luminy Aix Marseille Université Inserm, CNRS France
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5
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Narita TB, Schaap P, Saito T. Effects of deletion of the receptor CrlA on Dictyostelium aggregation and MPBD-mediated responses are strain dependent and not evident in strain Ax2. FEMS Microbiol Lett 2017; 364:2966322. [PMID: 28158557 DOI: 10.1093/femsle/fnx022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 01/24/2017] [Indexed: 11/14/2022] Open
Abstract
The polyketide MPBD (4-methyl-5-pentylbenzene-1, 3-diol) is produced by the polyketide synthase SteelyA (StlA) in Dictyostelium discoideum. MPBD is required for appropriate expression of cAMP signalling genes involved in cell aggregation and additionally induces the spore maturation at the fruiting body stage. The MPBD signalling pathway for regulation of cell aggregation is unknown, but MPBD effects on sporulation were reported to be mediated by the G-protein coupled receptor CrlA in D. discoideum KAx3. In this study, we deleted the crlA gene from the same parental strain (Ax2) that was used to generate the MPBD-less mutant. We found that unlike the MPBD-less mutant, Ax2-derived crlA- mutants exhibited normal cell aggregation, indicating that in Ax2 MPBD effects on early development do not require CrlA. We also found that the Ax2/crlA- mutant formed normal spores in fruiting bodies. When transformed with PkaC, both Ax2 and Ax2/crlA- similarly responded to MPBD in vitro with spore encapsulation. Our data make it doubtful that CrlA acts as the receptor for MPBD signalling during the development of D. discoideum Ax2.
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Affiliation(s)
- Takaaki B Narita
- Faculty of Science and Technology, Sophia University, Tokyo 102-8554, Japan.,School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Pauline Schaap
- School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Tamao Saito
- Faculty of Science and Technology, Sophia University, Tokyo 102-8554, Japan
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6
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Early nucleolar disorganization in Dictyostelium cell death. Cell Death Dis 2017; 8:e2528. [PMID: 28055008 PMCID: PMC5386361 DOI: 10.1038/cddis.2016.444] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 11/23/2016] [Accepted: 11/30/2016] [Indexed: 12/13/2022]
Abstract
Cell death occurs in all eukaryotes, but it is still not known whether some core steps of the cell death process are conserved. We investigated this using the protist Dictyostelium. The dissection of events in Dictyostelium vacuolar developmental cell death was facilitated by the sequential requirement for two distinct exogenous signals. An initial exogenous signal (starvation and cAMP) recruited some cells into clumps. Only within these clumps did subsequent cell death events take place. Contrary to our expectations, already this initial signal provoked nucleolar disorganization and irreversible inhibition of rRNA and DNA synthesis, reflecting marked cell dysfunction. The initial signal also primed clumped cells to respond to a second exogenous signal (differentiation-inducing factor-1 or c-di-GMP), which led to vacuolization and synthesis of cellulose encasings. Thus, the latter prominent hallmarks of developmental cell death were induced separately from initial cell dysfunction. We propose that (1) in Dictyostelium vacuolization and cellulose encasings are late, organism-specific, hallmarks, and (2) on the basis of our observations in this protist and of similar previous observations in some cases of mammalian cell death, early inhibition of rRNA synthesis and nucleolar disorganization may be conserved in some eukaryotes to usher in developmental cell death.
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Veltman DM, Williams TD, Bloomfield G, Chen BC, Betzig E, Insall RH, Kay RR. A plasma membrane template for macropinocytic cups. eLife 2016; 5:e20085. [PMID: 27960076 PMCID: PMC5154761 DOI: 10.7554/elife.20085] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 11/14/2016] [Indexed: 12/18/2022] Open
Abstract
Macropinocytosis is a fundamental mechanism that allows cells to take up extracellular liquid into large vesicles. It critically depends on the formation of a ring of protrusive actin beneath the plasma membrane, which develops into the macropinocytic cup. We show that macropinocytic cups in Dictyostelium are organised around coincident intense patches of PIP3, active Ras and active Rac. These signalling patches are invariably associated with a ring of active SCAR/WAVE at their periphery, as are all examined structures based on PIP3 patches, including phagocytic cups and basal waves. Patch formation does not depend on the enclosing F-actin ring, and patches become enlarged when the RasGAP NF1 is mutated, showing that Ras plays an instructive role. New macropinocytic cups predominantly form by splitting from existing ones. We propose that cup-shaped plasma membrane structures form from self-organizing patches of active Ras/PIP3, which recruit a ring of actin nucleators to their periphery.
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Affiliation(s)
- Douwe M Veltman
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
- Beatson Institute for Cancer Research, Glasgow, United Kingdom
| | | | | | - Bi-Chang Chen
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Eric Betzig
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Robert H Insall
- Beatson Institute for Cancer Research, Glasgow, United Kingdom
| | - Robert R Kay
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
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Mesquita A, Cardenal-Muñoz E, Dominguez E, Muñoz-Braceras S, Nuñez-Corcuera B, Phillips BA, Tábara LC, Xiong Q, Coria R, Eichinger L, Golstein P, King JS, Soldati T, Vincent O, Escalante R. Autophagy in Dictyostelium: Mechanisms, regulation and disease in a simple biomedical model. Autophagy 2016; 13:24-40. [PMID: 27715405 DOI: 10.1080/15548627.2016.1226737] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Autophagy is a fast-moving field with an enormous impact on human health and disease. Understanding the complexity of the mechanism and regulation of this process often benefits from the use of simple experimental models such as the social amoeba Dictyostelium discoideum. Since the publication of the first review describing the potential of D. discoideum in autophagy, significant advances have been made that demonstrate both the experimental advantages and interest in using this model. Since our previous review, research in D. discoideum has shed light on the mechanisms that regulate autophagosome formation and contributed significantly to the study of autophagy-related pathologies. Here, we review these advances, as well as the current techniques to monitor autophagy in D. discoideum. The comprehensive bioinformatics search of autophagic proteins that was a substantial part of the previous review has not been revisited here except for those aspects that challenged previous predictions such as the composition of the Atg1 complex. In recent years our understanding of, and ability to investigate, autophagy in D. discoideum has evolved significantly and will surely enable and accelerate future research using this model.
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Affiliation(s)
- Ana Mesquita
- a Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM) , Madrid , Spain.,b University of Cincinnati College of Medicine , Cincinnati , OH , USA
| | - Elena Cardenal-Muñoz
- c Départment de Biochimie , Faculté des Sciences, Université de Genève , Switzerland
| | - Eunice Dominguez
- a Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM) , Madrid , Spain.,d Departamento de Genética Molecular , Instituto de Fisiología Celular, Universidad Nacional Autónoma de México , Mexico City , México
| | - Sandra Muñoz-Braceras
- a Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM) , Madrid , Spain
| | | | - Ben A Phillips
- e Department of Biomedical Sciences , University of Sheffield , UK
| | - Luis C Tábara
- a Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM) , Madrid , Spain
| | - Qiuhong Xiong
- f Center for Biochemistry, Medical Faculty, University of Cologne , Cologne , Germany
| | - Roberto Coria
- d Departamento de Genética Molecular , Instituto de Fisiología Celular, Universidad Nacional Autónoma de México , Mexico City , México
| | - Ludwig Eichinger
- f Center for Biochemistry, Medical Faculty, University of Cologne , Cologne , Germany
| | - Pierre Golstein
- g Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université UM2 , Inserm, U1104, CNRS UMR7280, Marseille , France
| | - Jason S King
- e Department of Biomedical Sciences , University of Sheffield , UK
| | - Thierry Soldati
- c Départment de Biochimie , Faculté des Sciences, Université de Genève , Switzerland
| | - Olivier Vincent
- a Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM) , Madrid , Spain
| | - Ricardo Escalante
- a Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM) , Madrid , Spain
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9
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Mohamed W, Ray S, Brazill D, Baskar R. Absence of catalytic domain in a putative protein kinase C (PkcA) suppresses tip dominance in Dictyostelium discoideum. Dev Biol 2015; 405:10-20. [PMID: 26183108 DOI: 10.1016/j.ydbio.2015.05.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 04/06/2015] [Accepted: 05/28/2015] [Indexed: 12/22/2022]
Abstract
A number of organisms possess several isoforms of protein kinase C but little is known about the significance of any specific isoform during embryogenesis and development. To address this we characterized a PKC ortholog (PkcA; DDB_G0288147) in Dictyostelium discoideum. pkcA expression switches from prestalk in mound to prespore in slug, indicating a dynamic expression pattern. Mutants lacking the catalytic domain of PkcA (pkcA(-)) did not exhibit tip dominance. A striking phenotype of pkcA- was the formation of an aggregate with a central hollow, and aggregates later fragmented to form small mounds, each becoming a fruiting body. Optical density wave patterns of cAMP in the late aggregates showed several cAMP wave generation centers. We attribute these defects in pkcA(-) to impaired cAMP signaling, altered cell motility and decreased expression of the cell adhesion molecules - CadA and CsaA. pkcA(-) slugs showed ectopic expression of ecmA in the prespore region. Further, the use of a PKC-specific inhibitor, GF109203X that inhibits the activity of catalytic domain phenocopied pkcA(-).
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Affiliation(s)
- Wasima Mohamed
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Sibnath Ray
- Department of Biological Sciences, Center for Translational and Basic Research, Hunter College and The Graduate Center of the City University of New York, New York, NY 10065, USA
| | - Derrick Brazill
- Department of Biological Sciences, Center for Translational and Basic Research, Hunter College and The Graduate Center of the City University of New York, New York, NY 10065, USA
| | - Ramamurthy Baskar
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India.
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10
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Song Y, Luciani MF, Giusti C, Golstein P. c-di-GMP induction of Dictyostelium cell death requires the polyketide DIF-1. Mol Biol Cell 2014; 26:651-8. [PMID: 25518941 PMCID: PMC4325836 DOI: 10.1091/mbc.e14-08-1337] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Two inducers, DIF-1 and c-di-GMP, each separately shown to play a major role in Dictyostelium cell death induction in vitro, in fact cooperate. A similar cooperation with polyketides might occur for c-di-GMP effects in other situations and organisms, in particular in innate immunity and cell death in animal cells. Cell death in the model organism Dictyostelium, as studied in monolayers in vitro, can be induced by the polyketide DIF-1 or by the cyclical dinucleotide c-di-GMP. c-di-GMP, a universal bacterial second messenger, can trigger innate immunity in bacterially infected animal cells and is involved in developmental cell death in Dictyostelium. We show here that c-di-GMP was not sufficient to induce cell death in Dictyostelium cell monolayers. Unexpectedly, it also required the DIF-1 polyketide. The latter could be exogenous, as revealed by a telling synergy between c-di-GMP and DIF-1. The required DIF-1 polyketide could also be endogenous, as shown by the inability of c-di-GMP to induce cell death in Dictyostelium HMX44A cells and DH1 cells upon pharmacological or genetic inhibition of DIF-1 biosynthesis. In these cases, c-di-GMP–induced cell death was rescued by complementation with exogenous DIF-1. Taken together, these results demonstrated that c-di-GMP could trigger cell death in Dictyostelium only in the presence of the DIF-1 polyketide or its metabolites. This identified another element of control to this cell death and perhaps also to c-di-GMP effects in other situations and organisms.
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Affiliation(s)
- Yu Song
- Centre d'Immunologie de Marseille-Luminy, UM2 Aix-Marseille Université; Institut National de la Santé et de la Recherche Médicale, U1104; and Centre National de la Recherche Scientifique, UMR7280, 13288 Marseille, France
| | - Marie-Françoise Luciani
- Centre d'Immunologie de Marseille-Luminy, UM2 Aix-Marseille Université; Institut National de la Santé et de la Recherche Médicale, U1104; and Centre National de la Recherche Scientifique, UMR7280, 13288 Marseille, France
| | - Corinne Giusti
- Centre d'Immunologie de Marseille-Luminy, UM2 Aix-Marseille Université; Institut National de la Santé et de la Recherche Médicale, U1104; and Centre National de la Recherche Scientifique, UMR7280, 13288 Marseille, France
| | - Pierre Golstein
- Centre d'Immunologie de Marseille-Luminy, UM2 Aix-Marseille Université; Institut National de la Santé et de la Recherche Médicale, U1104; and Centre National de la Recherche Scientifique, UMR7280, 13288 Marseille, France
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11
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Clark J, Kay RR, Kielkowska A, Niewczas I, Fets L, Oxley D, Stephens LR, Hawkins PT. Dictyostelium uses ether-linked inositol phospholipids for intracellular signalling. EMBO J 2014; 33:2188-200. [PMID: 25180230 DOI: 10.15252/embj.201488677] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Inositol phospholipids are critical regulators of membrane biology throughout eukaryotes. The general principle by which they perform these roles is conserved across species and involves binding of differentially phosphorylated inositol head groups to specific protein domains. This interaction serves to both recruit and regulate the activity of several different classes of protein which act on membrane surfaces. In mammalian cells, these phosphorylated inositol head groups are predominantly borne by a C38:4 diacylglycerol backbone. We show here that the inositol phospholipids of Dictyostelium are different, being highly enriched in an unusual C34:1e lipid backbone, 1-hexadecyl-2-(11Z-octadecenoyl)-sn-glycero-3-phospho-(1'-myo-inositol), in which the sn-1 position contains an ether-linked C16:0 chain; they are thus plasmanylinositols. These plasmanylinositols respond acutely to stimulation of cells with chemoattractants, and their levels are regulated by PIPKs, PI3Ks and PTEN. In mammals and now in Dictyostelium, the hydrocarbon chains of inositol phospholipids are a highly selected subset of those available to other phospholipids, suggesting that different molecular selectors are at play in these organisms but serve a common, evolutionarily conserved purpose.
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Affiliation(s)
- Jonathan Clark
- Babraham Biosciences Technology Babraham Research Campus, Cambridge, UK
| | - Robert R Kay
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Anna Kielkowska
- Babraham Biosciences Technology Babraham Research Campus, Cambridge, UK
| | - Izabella Niewczas
- Babraham Biosciences Technology Babraham Research Campus, Cambridge, UK
| | - Louise Fets
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - David Oxley
- Signalling Programme Babraham Research Campus, Cambridge, UK
| | - Len R Stephens
- Signalling Programme Babraham Research Campus, Cambridge, UK
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12
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Hirst J, Schlacht A, Norcott JP, Traynor D, Bloomfield G, Antrobus R, Kay RR, Dacks JB, Robinson MS. Characterization of TSET, an ancient and widespread membrane trafficking complex. eLife 2014; 3:e02866. [PMID: 24867644 PMCID: PMC4031984 DOI: 10.7554/elife.02866] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The heterotetrameric AP and F-COPI complexes help to define the cellular map of modern eukaryotes. To search for related machinery, we developed a structure-based bioinformatics tool, and identified the core subunits of TSET, a 'missing link' between the APs and COPI. Studies in Dictyostelium indicate that TSET is a heterohexamer, with two associated scaffolding proteins. TSET is non-essential in Dictyostelium, but may act in plasma membrane turnover, and is essentially identical to the recently described TPLATE complex, TPC. However, whereas TPC was reported to be plant-specific, we can identify a full or partial complex in every eukaryotic supergroup. An evolutionary path can be deduced from the earliest origins of the heterotetramer/scaffold coat to its multiple manifestations in modern organisms, including the mammalian muniscins, descendants of the TSET medium subunits. Thus, we have uncovered the machinery for an ancient and widespread pathway, which provides new insights into early eukaryotic evolution.DOI: http://dx.doi.org/10.7554/eLife.02866.001.
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Affiliation(s)
- Jennifer Hirst
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | | | - John P Norcott
- Department of Engineering, University of Cambridge, Cambridge, United Kingdom
| | - David Traynor
- Cell Biology, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Gareth Bloomfield
- Cell Biology, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Robin Antrobus
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Robert R Kay
- Cell Biology, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Joel B Dacks
- Department of Cell Biology, University of Alberta, Edmonton, Canada
| | - Margaret S Robinson
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
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13
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Zatulovskiy E, Tyson R, Bretschneider T, Kay RR. Bleb-driven chemotaxis of Dictyostelium cells. ACTA ACUST UNITED AC 2014; 204:1027-44. [PMID: 24616222 PMCID: PMC3998804 DOI: 10.1083/jcb.201306147] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Blebs and F-actin-driven pseudopods are alternative ways of extending the leading edge of migrating cells. We show that Dictyostelium cells switch from using predominantly pseudopods to blebs when migrating under agarose overlays of increasing stiffness. Blebs expand faster than pseudopods leaving behind F-actin scars, but are less persistent. Blebbing cells are strongly chemotactic to cyclic-AMP, producing nearly all of their blebs up-gradient. When cells re-orientate to a needle releasing cyclic-AMP, they stereotypically produce first microspikes, then blebs and pseudopods only later. Genetically, blebbing requires myosin-II and increases when actin polymerization or cortical function is impaired. Cyclic-AMP induces transient blebbing independently of much of the known chemotactic signal transduction machinery, but involving PI3-kinase and downstream PH domain proteins, CRAC and PhdA. Impairment of this PI3-kinase pathway results in slow movement under agarose and cells that produce few blebs, though actin polymerization appears unaffected. We propose that mechanical resistance induces bleb-driven movement in Dictyostelium, which is chemotactic and controlled through PI3-kinase.
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14
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Platt JL, Rogers BJ, Rogers KC, Harwood AJ, Kimmel AR. Different CHD chromatin remodelers are required for expression of distinct gene sets and specific stages during development of Dictyostelium discoideum. Development 2014; 140:4926-36. [PMID: 24301467 PMCID: PMC3848188 DOI: 10.1242/dev.099879] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Control of chromatin structure is crucial for multicellular development and regulation of cell differentiation. The CHD (chromodomain-helicase-DNA binding) protein family is one of the major ATP-dependent, chromatin remodeling factors that regulate nucleosome positioning and access of transcription factors and RNA polymerase to the eukaryotic genome. There are three mammalian CHD subfamilies and their impaired functions are associated with several human diseases. Here, we identify three CHD orthologs (ChdA, ChdB and ChdC) in Dictyostelium discoideum. These CHDs are expressed throughout development, but with unique patterns. Null mutants lacking each CHD have distinct phenotypes that reflect their expression patterns and suggest functional specificity. Accordingly, using genome-wide (RNA-seq) transcriptome profiling for each null strain, we show that the different CHDs regulate distinct gene sets during both growth and development. ChdC is an apparent ortholog of the mammalian Class III CHD group that is associated with the human CHARGE syndrome, and GO analyses of aberrant gene expression in chdC nulls suggest defects in both cell-autonomous and non-autonomous signaling, which have been confirmed through analyses of chdC nulls developed in pure populations or with low levels of wild-type cells. This study provides novel insight into the broad function of CHDs in the regulation development and disease, through chromatin-mediated changes in directed gene expression.
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Affiliation(s)
- James L Platt
- Laboratory of Cellular and Developmental Biology, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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Abstract
Transcriptional control of developmental genes is important for cell differentiation and pattern formation. Developing Dictyostelium discoideum cells form a multicellular structure in which individual cells differentiate into either stalk cells or spores. This simplicity makes the organism an attractive model for studying fundamental problems in developmental biology. However, the morphogenetic process of forming a stalked fruiting body conceals a certain degree of complexity. This is reflected in the presence of multiple prestalk subtypes that have individual roles to generate the fruiting body. This review describes recent advances in understanding the molecular mechanisms, mediated by transcription factors that generate prestalk-cell heterogeneity.
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Affiliation(s)
- Masashi Fukuzawa
- Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Aomori 036-8561, Japan.
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Abstract
Shwachman-Diamond syndrome (SDS), a recessive leukemia predisposition disorder characterized by bone marrow failure, exocrine pancreatic insufficiency, skeletal abnormalities and poor growth, is caused by mutations in the highly conserved SBDS gene. Here, we test the hypothesis that defective ribosome biogenesis underlies the pathogenesis of SDS. We create conditional mutants in the essential SBDS ortholog of the ancient eukaryote Dictyostelium discoideum using temperature-sensitive, self-splicing inteins, showing that mutant cells fail to grow at the restrictive temperature because ribosomal subunit joining is markedly impaired. Remarkably, wild type human SBDS complements the growth and ribosome assembly defects in mutant Dictyostelium cells, but disease-associated human SBDS variants are defective. SBDS directly interacts with the GTPase elongation factor-like 1 (EFL1) on nascent 60S subunits in vivo and together they catalyze eviction of the ribosome antiassociation factor eukaryotic initiation factor 6 (eIF6), a prerequisite for the translational activation of ribosomes. Importantly, lymphoblasts from SDS patients harbor a striking defect in ribosomal subunit joining whose magnitude is inversely proportional to the level of SBDS protein. These findings in Dictyostelium and SDS patient cells provide compelling support for the hypothesis that SDS is a ribosomopathy caused by corruption of an essential cytoplasmic step in 60S subunit maturation.
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Myre MA, Lumsden AL, Thompson MN, Wasco W, MacDonald ME, Gusella JF. Deficiency of huntingtin has pleiotropic effects in the social amoeba Dictyostelium discoideum. PLoS Genet 2011; 7:e1002052. [PMID: 21552328 PMCID: PMC3084204 DOI: 10.1371/journal.pgen.1002052] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Accepted: 03/02/2011] [Indexed: 11/24/2022] Open
Abstract
Huntingtin is a large HEAT repeat protein first identified in humans, where a polyglutamine tract expansion near the amino terminus causes a gain-of-function mechanism that leads to selective neuronal loss in Huntington's disease (HD). Genetic evidence in humans and knock-in mouse models suggests that this gain-of-function involves an increase or deregulation of some aspect of huntingtin's normal function(s), which remains poorly understood. As huntingtin shows evolutionary conservation, a powerful approach to discovering its normal biochemical role(s) is to study the effects caused by its deficiency in a model organism with a short life-cycle that comprises both cellular and multicellular developmental stages. To facilitate studies aimed at detailed knowledge of huntingtin's normal function(s), we generated a null mutant of hd, the HD ortholog in Dictyostelium discoideum. Dictyostelium cells lacking endogenous huntingtin were viable but during development did not exhibit the typical polarized morphology of Dictyostelium cells, streamed poorly to form aggregates by accretion rather than chemotaxis, showed disorganized F-actin staining, exhibited extreme sensitivity to hypoosmotic stress, and failed to form EDTA-resistant cell–cell contacts. Surprisingly, chemotactic streaming could be rescued in the presence of the bivalent cations Ca2+ or Mg2+ but not pulses of cAMP. Although hd− cells completed development, it was delayed and proceeded asynchronously, producing small fruiting bodies with round, defective spores that germinated spontaneously within a glassy sorus. When developed as chimeras with wild-type cells, hd− cells failed to populate the pre-spore region of the slug. In Dictyostelium, huntingtin deficiency is compatible with survival of the organism but renders cells sensitive to low osmolarity, which produces pleiotropic cell autonomous defects that affect cAMP signaling and as a consequence development. Thus, Dictyostelium provides a novel haploid organism model for genetic, cell biological, and biochemical studies to delineate the functions of the HD protein. Genetic evidence in humans and mouse models of Huntington's disease suggests that the disease mutation confers a deleterious gain-of-function on huntingtin that acts through the deregulation of some aspect of the protein's normal function(s). While huntingtin's function is poorly understood, its evolutionary conservation makes investigation of its physiological role in lower organisms an attractive route that has yet to be fully exploited. Therefore, we have used Dictyostelium discoideum to study the consequences of huntingtin (hd) deficiency. Developing Dictyostelium cells chemotax to form a multicellular slug that forms a fruiting body, comprising dormant spores encased above dead stalk cells. We found that hd− cells were hypersensitive to hypoosmotic stress. When starved, hd− cells aggregate by accretion, showed disorganized F-actin, and failed to form EDTA-resistant cell–cell contacts. Surprisingly, chemotactic signaling was rescued with Ca2+ or Mg2+ but not pulses of cAMP. Development of hd− mutants produced small fruiting bodies with round, defective spores, and when mixed with wild-type cells they didn't differentiate into spores. Our results are consistent with mammalian studies that show huntingtin is a multifunctional protein involved in many biochemical processes; and, importantly, they establish Dictyostelium as a valuable experimental organism for exploring in biochemical detail huntingtin's normal function(s).
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Affiliation(s)
- Michael A. Myre
- Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- * E-mail:
| | - Amanda L. Lumsden
- Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Morgan N. Thompson
- Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Wilma Wasco
- Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Charlestown, Massachusetts, United States of America
| | - Marcy E. MacDonald
- Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - James F. Gusella
- Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
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Protein kinase B gene homologue pkbR1 performs one of its roles at first finger stage of Dictyostelium. EUKARYOTIC CELL 2011; 10:512-20. [PMID: 21335531 DOI: 10.1128/ec.00200-10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Dictyostelium discoideum has protein kinases AKT/PKBA and PKBR1 that belong to the AGC family of kinases. The protein kinase B-related kinase (PKBR1) has been studied with emphasis on its role in chemotaxis, but its roles in late development remained obscure. The pkbR1 null mutant stays in the first finger stage for about 16 h or longer. Only a few aggregates continue to the migrating slug stage; however, the slugs immediately go back probably to the previous first finger stage and stay there for approximately 37 h. Finally, the mutant fingers diversify into various multicellular bodies. The expression of the pkbR1 finger protein probably is required for development to the slug stage and to express ecmB, which is first observed in migrating slugs. The mutant also showed no ST-lacZ expression, which is of the earliest step in differentiation to one of the stalk cell subtypes. The pkbR1 null mutant forms a small number of aberrant fruiting bodies, but in the presence of 10% of wild-type amoebae the mutant preferentially forms viable spores, driving the wild type to form nonviable stalk cells. These results suggest that the mutant has defects in a system that changes the physiological dynamics in the prestalk cell region of a finger. We suggest that the arrest of its development is due to the loss of the second wave of expression of a protein kinase A catalytic subunit gene (pkaC) only in the prestalk region of the pkbR1 null mutant.
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Kim L, Brzostowski J, Majithia A, Lee NS, McMains V, Kimmel AR. Combinatorial cell-specific regulation of GSK3 directs cell differentiation and polarity in Dictyostelium. Development 2011; 138:421-30. [PMID: 21205787 DOI: 10.1242/dev.055335] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
In Dictyostelium, the interaction of secreted cAMP with specific cell surface receptors regulates the activation/de-activation of GSK3, which mediates developmental cell patterning. In addition, Dictyostelium cells polarize in response to extracellular cAMP, although a potential role for GSK3 in this pathway has not been investigated. Previously, we had shown that ZAK1 was an activating tyrosine kinase for GSK3 function in Dictyostelium and we now identify ZAK2 as the other tyrosine kinase in the cAMP-activation pathway for GSK3; no additional family members exist. We also now show that tyrosine phosphorylation/activation of GSK3 by ZAK2 and ZAK1 separately regulate GSK3 in distinct differentiated cell populations, and that ZAK2 acts in both autonomous and non-autonomous pathways to regulate these cell-type differentiations. Finally, we demonstrate that efficient polarization of Dictyostelium towards cAMP depends on ZAK1-mediated tyrosine phosphorylation of GSK3. Combinatorial regulation of GSK3 by ZAK kinases in Dictyostelium guides cell polarity, directional cell migration and cell differentiation, pathways that extend the complexity of GSK3 signaling throughout the development of Dictyostelium.
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Affiliation(s)
- Leung Kim
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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Zanchi R, Howard G, Bretscher MS, Kay RR. The exocytic gene secA is required for Dictyostelium cell motility and osmoregulation. J Cell Sci 2010; 123:3226-34. [PMID: 20807800 DOI: 10.1242/jcs.072876] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We investigated the link between cell movement and plasma membrane recycling using a fast-acting, temperature-sensitive mutant of the Dictyostelium SecA exocytic protein. Strikingly, most mutant cells become almost paralysed within minutes at the restrictive temperature. However, they can still sense cyclic-AMP (cAMP) gradients and polymerise actin up-gradient, but form only abortive pseudopodia, which cannot expand. They also relay a cAMP signal normally, suggesting that cAMP is released by a non-exocytic mechanism. To investigate why SecA is required for motility, we examined membrane trafficking in the mutant. Plasma membrane circulation is rapidly inhibited at the restrictive temperature and the cells acquire a prominent vesicle. Organelle-specific markers show that this is an undischarged contractile vacuole, and we found the cells are correspondingly osmo-sensitive. Electron microscopy shows that many smaller vesicles, probably originating from the plasma membrane, also accumulate at the restrictive temperature. Consistent with this, the surface area of mutant cells shrinks. We suggest that SecA mutant cells cannot move at the restrictive temperature because their block in exocytosis results in a net uptake of plasma membrane, reducing its area, and so restricting pseudopodial expansion. This demonstrates the importance of proper surface area regulation in cell movement.
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Affiliation(s)
- Roberto Zanchi
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 0QH, UK
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21
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McMains VC, Myre M, Kreppel L, Kimmel AR. Dictyostelium possesses highly diverged presenilin/gamma-secretase that regulates growth and cell-fate specification and can accurately process human APP: a system for functional studies of the presenilin/gamma-secretase complex. Dis Model Mech 2010; 3:581-94. [PMID: 20699477 DOI: 10.1242/dmm.004457] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Presenilin (PS) is the catalytic moiety of the gamma-secretase complex. PS and other gamma-secretase components are well conserved among metazoa, but their presence and function in more-distant species are not resolved. Because inappropriate gamma-secretase processing of amyloid precursor protein (APP) in humans is associated with familial Alzheimer's disease, understanding essential elements within each gamma-secretase component is crucial to functional studies. Diverged proteins have been identified in primitive plants but experiments have failed to demonstrate gamma-secretase activity. We have identified highly diverged orthologs for each gamma-secretase component in the ancient eukaryote Dictyostelium, which lacks equivalents of APP, Notch and other characterized PS/gamma-secretase substrates. We show that wild-type (WT) Dictyostelium is capable of amyloidogenic processing of ectopically expressed human APP to generate amyloid-beta peptides Abeta(40) and Abeta(42); strains deficient in gamma-secretase cannot produce Abeta peptides but accumulate processed intermediates of APP that co-migrate with the C-terminal fragments alpha- and beta-CTF of APP that are found in mammalian cells. We further demonstrate that Dictyostelium requires PS for phagocytosis and cell-fate specification in a cell-autonomous manner, and show that regulation of phagocytosis requires an active gamma-secretase, a pathway suggested, but not proven, to occur in mammalian and Drosophila cells. Our results indicate that PS signaling is an ancient process that arose prior to metazoan radiation, perhaps independently of Notch. Dictyostelium might serve to identify novel PS/gamma-secretase signaling targets and provide a unique system for high-throughput screening of small-molecule libraries to select new therapeutic targets for diseases associated with this pathway.
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Affiliation(s)
- Vanessa C McMains
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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Giusti C, Luciani MF, Ravens S, Gillet A, Golstein P. Autophagic cell death in Dictyostelium requires the receptor histidine kinase DhkM. Mol Biol Cell 2010; 21:1825-35. [PMID: 20375146 PMCID: PMC2877641 DOI: 10.1091/mbc.e09-11-0976] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Through random mutagenesis, the receptor histidine kinase DhkM was found essential for autophagic cell death (ACD) in Dictyostelium. DhkM is the most downstream known molecule required for this model ACD. Different DhkM mutants showed distinct non-vacuolizing ACD phenotypes and genetically separated previously undissociated late cell death events. Dictyostelium constitutes a genetically tractable model for the analysis of autophagic cell death (ACD). During ACD, Dictyostelium cells first transform into paddle cells and then become round, synthesize cellulose, vacuolize, and die. Through random insertional mutagenesis, we identified the receptor histidine kinase DhkM as being essential for ACD. Surprisingly, different DhkM mutants showed distinct nonvacuolizing ACD phenotypes. One class of mutants arrested ACD at the paddle cell stage, perhaps through a dominant-negative effect. Other mutants, however, progressed further in the ACD program. They underwent rounding and cellulose synthesis but stopped before vacuolization. Moreover, they underwent clonogenic but not morphological cell death. Exogenous 8-bromo-cAMP restored vacuolization and death. A role for a membrane receptor at a late stage of the ACD pathway is puzzling, raising questions as to which ligand it is a receptor for and which moieties it phosphorylates. Together, DhkM is the most downstream-known molecule required for this model ACD, and its distinct mutants genetically separate previously undissociated late cell death events.
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Affiliation(s)
- Corinne Giusti
- Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, Marseille F-13288, France
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Giusti C, Tresse E, Luciani MF, Golstein P. Autophagic cell death: analysis in Dictyostelium. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1793:1422-31. [PMID: 19133302 DOI: 10.1016/j.bbamcr.2008.12.005] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2008] [Revised: 12/04/2008] [Accepted: 12/04/2008] [Indexed: 11/24/2022]
Abstract
Autophagic cell death (ACD) can be operationally described as cell death with an autophagic component. While most molecular bases of this autophagic component are known, in ACD the mechanism of cell death proper is not well defined, in particular because in animal cells there is poor experimental distinction between what triggers autophagy and what triggers ACD. Perhaps as a consequence, it is often thought that in animal cells a little autophagy is protective while a lot is destructive and leads to ACD, thus that the shift from autophagy to ACD is quantitative. The aim of this article is to review current knowledge on ACD in Dictyostelium, a very favorable model, with emphasis on (1) the qualitative, not quantitative nature of the shift from autophagy to ACD, in contrast to the above, and (2) random or targeted mutations of in particular the following genes: iplA (IP3R), TalB (talinB), DcsA (cellulose synthase), GbfA, ugpB, glcS (glycogen synthase) and atg1. These mutations allowed the genetic dissection of ACD features, dissociating in particular vacuolisation from cell death.
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Affiliation(s)
- Corinne Giusti
- Centre d'Immunologie de Marseille-Luminy (CIML), Aix-Marseille Université, INSERM U631, CNRS UMR6102, Case 906, Faculté des Sciences de Luminy, Marseille F-13288, France
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Autophagic or necrotic cell death triggered by distinct motifs of the differentiation factor DIF-1. Cell Death Differ 2008; 16:564-70. [PMID: 19079140 DOI: 10.1038/cdd.2008.177] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Autophagic or necrotic cell death (ACD and NCD, respectively), studied in the model organism Dictyostelium which offers unique advantages, require triggering by the same differentiation-inducing factor DIF-1. To initiate these two types of cell death, does DIF-1 act through only one or through two distinct recognition structures? Such distinct structures may recognize distinct motifs of DIF-1. To test this albeit indirectly, DIF-1 was modified at one or two of several positions, and the corresponding derivatives were tested for their abilities to induce ACD or NCD. The results strongly indicated that distinct biochemical motifs of DIF-1 were required to trigger ACD or NCD, and that these motifs were separately recognized at the onset of ACD or NCD. In addition, both ACD and NCD were induced more efficiently by DIF-1 than by either its precursors or its immediate catabolite. These results showed an unexpected relation between a differentiation factor, the cellular structures that recognize it, the cell death types it can trigger and the metabolic state of the cell. The latter seems to guide the choice of the signaling pathway to cell death, which in turn imposes the cell death type and the recognition pattern of the differentiation factor.
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Giusti C, Luciani MF, Klein G, Aubry L, Tresse E, Kosta A, Golstein P. Necrotic cell death: From reversible mitochondrial uncoupling to irreversible lysosomal permeabilization. Exp Cell Res 2008; 315:26-38. [PMID: 18951891 DOI: 10.1016/j.yexcr.2008.09.028] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2008] [Revised: 09/24/2008] [Accepted: 09/24/2008] [Indexed: 11/19/2022]
Abstract
Dictyostelium atg1- mutant cells provide an experimentally and genetically favorable model to study necrotic cell death (NCD) with no interference from apoptosis or autophagy. In such cells subjected to starvation and cAMP, induction by the differentiation-inducing factor DIF or by classical uncouplers led within minutes to mitochondrial uncoupling, which causally initiated NCD. We now report that (1) in this model, NCD included a mitochondrial-lysosomal cascade of events, (2) mitochondrial uncoupling and therefore initial stages of death showed reversibility for a surprisingly long time, (3) subsequent lysosomal permeabilization could be demonstrated using Lysosensor blue, acridin orange, Texas red-dextran and cathepsin B substrate, (4) this lysosomal permeabilization was irreversible, and (5) the presence of the uncoupler was required to maintain mitochondrial lesions but also to induce lysosomal lesions, suggesting that signaling from mitochondria to lysosomes must be sustained by the continuous presence of the uncoupler. These results further characterized the NCD pathway in this priviledged model, contributed to a definition of NCD at the lysosomal level, and suggested that in mammalian NCD even late reversibility attempts by removal of the inducer may be of therapeutic interest.
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Affiliation(s)
- Corinne Giusti
- Centre d'Immunologie de Marseille-Luminy (CIML), Faculté des Sciences de Luminy, Aix Marseille Université, Marseille F-13288, France
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26
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Kosta A, Luciani MF, Geerts WJ, Golstein P. Marked mitochondrial alterations upon starvation without cell death, caspases or Bcl-2 family members. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:2013-9. [DOI: 10.1016/j.bbamcr.2008.06.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Revised: 06/03/2008] [Accepted: 06/09/2008] [Indexed: 10/21/2022]
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Bloomfield G, Tanaka Y, Skelton J, Ivens A, Kay RR. Widespread duplications in the genomes of laboratory stocks of Dictyostelium discoideum. Genome Biol 2008; 9:R75. [PMID: 18430225 PMCID: PMC2643946 DOI: 10.1186/gb-2008-9-4-r75] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Revised: 03/19/2008] [Accepted: 04/22/2008] [Indexed: 12/01/2022] Open
Abstract
Background Duplications of stretches of the genome are an important source of individual genetic variation, but their unrecognized presence in laboratory organisms would be a confounding variable for genetic analysis. Results We report here that duplications of 15 kb or more are common in the genome of the social amoeba Dictyostelium discoideum. Most stocks of the axenic 'workhorse' strains Ax2 and Ax3/4 obtained from different laboratories can be expected to carry different duplications. The auxotrophic strains DH1 and JH10 also bear previously unreported duplications. Strain Ax3/4 is known to carry a large duplication on chromosome 2 and this structure shows evidence of continuing instability; we find a further variable duplication on chromosome 5. These duplications are lacking in Ax2, which has instead a small duplication on chromosome 1. Stocks of the type isolate NC4 are similarly variable, though we have identified some approximating the assumed ancestral genotype. More recent wild-type isolates are almost without large duplications, but we can identify small deletions or regions of high divergence, possibly reflecting responses to local selective pressures. Duplications are scattered through most of the genome, and can be stable enough to reconstruct genealogies spanning decades of the history of the NC4 lineage. The expression level of many duplicated genes is increased with dosage, but for others it appears that some form of dosage compensation occurs. Conclusion The genetic variation described here must underlie some of the phenotypic variation observed between strains from different laboratories. We suggest courses of action to alleviate the problem.
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Affiliation(s)
- Gareth Bloomfield
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK.
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Giusti C, Kosta A, Lam D, Tresse E, Luciani MF, Golstein P. Analysis of autophagic and necrotic cell death in Dictyostelium. Methods Enzymol 2008; 446:1-15. [PMID: 18603113 DOI: 10.1016/s0076-6879(08)01601-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Non-apoptotic cell death types can be conveniently studied in Dictyostelium discoideum, an exceptionally favorable model not only because of its well-known genetic and experimental advantages, but also because in Dictyostelium there is no apoptosis machinery that could interfere with non-apoptotic cell death. We show here how to conveniently demonstrate, assess, and study these non-apoptotic cell death types. These can be generated by use of modifications of the monolayer technique of Rob Kay et al., and either wild-type HMX44A Dictyostelium cells, leading to autophagic cell death, or the corresponding atg1- autophagy gene mutant cells, leading to necrotic cell death. Methods to follow these non-apoptotic cell death types qualitatively and quantitatively will be reported.
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Affiliation(s)
- Corinne Giusti
- Centre d'Immunologie INSERM-CNRS-Univ.Medit. de Marseille-Luminy, Marseille, France
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Tresse E, Giusti C, Kosta A, Luciani M, Golstein P. Chapter 23 Autophagy and Autophagic Cell Death in Dictyostelium. Methods Enzymol 2008; 451:343-58. [DOI: 10.1016/s0076-6879(08)03223-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Lam D, Kosta A, Luciani MF, Golstein P. The inositol 1,4,5-trisphosphate receptor is required to signal autophagic cell death. Mol Biol Cell 2007; 19:691-700. [PMID: 18077554 DOI: 10.1091/mbc.e07-08-0823] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The signaling pathways governing pathophysiologically important autophagic (ACD) and necrotic (NCD) cell death are not entirely known. In the Dictyostelium eukaryote model, which benefits from both unique analytical and genetic advantages and absence of potentially interfering apoptotic machinery, the differentiation factor DIF leads from starvation-induced autophagy to ACD, or, if atg1 is inactivated, to NCD. Here, through random insertional mutagenesis, we found that inactivation of the iplA gene, the only gene encoding an inositol 1,4,5-trisphosphate receptor (IP3R) in this organism, prevented ACD. The IP3R is a ligand-gated channel governing Ca(2+) efflux from endoplasmic reticulum stores to the cytosol. Accordingly, Ca(2+)-related drugs also affected DIF signaling leading to ACD. Thus, in this system, a main pathway signaling ACD requires IP3R and further Ca(2+)-dependent steps. This is one of the first insights in the molecular understanding of a signaling pathway leading to autophagic cell death.
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Affiliation(s)
- David Lam
- Centre d'Immunologie de Marseille-Luminy, Institut National de la Santé et de la Recherche Médicale U631, and Centre National de la Recherche Scientifique Unité Mixte de Recherche 6102, Aix Marseille Université, Marseille, France
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Lam D, Levraud JP, Luciani MF, Golstein P. Autophagic or necrotic cell death in the absence of caspase and bcl-2 family members. Biochem Biophys Res Commun 2007; 363:536-41. [PMID: 17889831 DOI: 10.1016/j.bbrc.2007.09.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Accepted: 09/02/2007] [Indexed: 11/15/2022]
Abstract
How is one to investigate autophagic or necrotic cell death in the absence of interference from the apoptosis machinery? In the protist Dictyostelium, a model for the study of these two cell death types, we previously showed that autophagic cell death does not require paracaspase, the only caspase family member in this organism. In this report, we prepared two distinct paracaspase- atg1- double mutants, and we used them to demonstrate that paracaspase is not required for necrotic cell death either. Also, in silico investigation showed that the genome of Dictyostelium harbored no detectable member of the bcl-2 family and no single BH3 domain-bearing molecules. Altogether, in this model system both autophagic and necrotic cell death could occur, and could be investigated, with no interference from the two main molecular families involved in apoptosis, the caspase and the bcl-2 families.
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Affiliation(s)
- David Lam
- Centre d'Immunologie de Marseille-Luminy, Case 906, Faculté des Sciences de Luminy, 13288 Marseille Cedex 9, France
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32
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Mattei S, Klein G, Satre M, Aubry L. Trafficking and developmental signaling: Alix at the crossroads. Eur J Cell Biol 2007; 85:925-36. [PMID: 16766083 DOI: 10.1016/j.ejcb.2006.04.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Alix is a phylogenetically conserved protein that participates in mammals in programmed cell death in association with ALG-2, a penta-EF-hand calciprotein. It contains an N-terminal Bro1 domain, a coiled-coil region and a C-terminal proline-rich domain containing several SH3- and WW-binding sites that contribute to its scaffolding properties. Recent data showed that by virtue of its Bro1 domain, Alix is functionally associated to the ESCRT complexes involved in the biogenesis of the multivesicular body and sorting of transmembrane proteins within this specific endosomal compartment. In Dictyostelium, an alx null strain shows a markedly perturbed starvation-induced morphogenetic program while ALG-2 disruptants remain unaffected. This review summarizes Dictyostelium data on Alix and ALG-2 homologues and evaluates whether known functions of Alix in other organisms can account for the developmental arrest of the alx null mutant and how Dictyostelium studies can substantiate the current understanding of the function(s) of this versatile and conserved signaling molecule.
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Affiliation(s)
- Sara Mattei
- Laboratoire de Biochimie et Biophysique des Systemes Integres, DRDC/BBSI, UMR 5092 CNRS-CEA-UJF, CEA-Grenoble, 17 Rue des Martyrs, F-38054 Grenoble cedex 9, France
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Serafimidis I, Bloomfield G, Skelton J, Ivens A, Kay RR. A new environmentally resistant cell type from Dictyostelium. MICROBIOLOGY-SGM 2007; 153:619-630. [PMID: 17259634 PMCID: PMC2786962 DOI: 10.1099/mic.0.2006/000562-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
This paper describes the serendipitous discovery and first characterization of a new resistant cell type from Dictyostelium, for which the name aspidocyte (from aspis: Greek for shield) is proposed. These cells are induced from amoebae by a range of toxins including heavy metals and antibiotics, and were first detected by their striking resistance to detergent lysis. Aspidocytes are separate, rounded or irregular-shaped cells, which are immotile but remain fully viable; once the toxic stress is removed, they revert to amoeboid cells within an hour. Induction takes a few hours and is completely blocked by the protein synthesis inhibitor cycloheximide. Aspidocytes lack a cell wall and their resistance to detergent lysis is active, requiring continued energy metabolism, and may be assisted by a complete cessation of endocytosis, as measured by uptake of the dye FM1-43. Microarray analysis shows that aspidocytes have a distinct pattern of gene expression, with a number of genes up-regulated that are predicted to be involved in lipid metabolism. Aspidocytes were initially detected in a hypersensitive mutant, in which the AMP deaminase gene is disrupted, suggesting that the inductive pathway involves AMP levels or metabolism. Since aspidocytes can also be induced from wild-type cells and are much more resistant than amoebae to a membrane-disrupting antibiotic, it is possible that they are an adaptation allowing Dictyostelium cells to survive a sudden onslaught of toxins in the wild.
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Affiliation(s)
| | - Gareth Bloomfield
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK
| | - Jason Skelton
- The Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire CB10 1SA, UK
| | - Al Ivens
- The Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire CB10 1SA, UK
| | - Robert R. Kay
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK
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Tresse E, Kosta A, Luciani MF, Golstein P. From autophagic to necrotic cell death in Dictyostelium. Semin Cancer Biol 2006; 17:94-100. [PMID: 17150370 DOI: 10.1016/j.semcancer.2006.10.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2006] [Accepted: 10/31/2006] [Indexed: 11/28/2022]
Abstract
Among unusual models to study cell death mechanisms, the protist Dictyostelium is remarkable because of its strategic phylogenetic position, with early emergence among eukaryotes and unicellular/multicellular transition, and its very favorable experimental and genetic flexibility. Dictyostelium shows developmental vacuolar cell death, and in vitro monolayer approaches revealed both an autophagic vacuolar and a necrotic type of cell death. These are described in some detail, as well as implications and future prospects.
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Affiliation(s)
- Emilie Tresse
- Centre d'Immunologie de Marseille-Luminy, Université de la Méditerranée, Case 906, 13288 Marseille Cedex 9, France
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35
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Austin MB, Saito T, Bowman ME, Haydock S, Kato A, Moore BS, Kay RR, Noel JP. Biosynthesis of Dictyostelium discoideum differentiation-inducing factor by a hybrid type I fatty acid-type III polyketide synthase. Nat Chem Biol 2006; 2:494-502. [PMID: 16906151 PMCID: PMC2864586 DOI: 10.1038/nchembio811] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2006] [Accepted: 07/13/2006] [Indexed: 11/08/2022]
Abstract
Differentiation-inducing factors (DIFs) are well known to modulate formation of distinct communal cell types from identical Dictyostelium discoideum amoebas, but DIF biosynthesis remains obscure. We report complimentary in vivo and in vitro experiments identifying one of two approximately 3,000-residue D. discoideum proteins, termed 'steely', as responsible for biosynthesis of the DIF acylphloroglucinol scaffold. Steely proteins possess six catalytic domains homologous to metazoan type I fatty acid synthases (FASs) but feature an iterative type III polyketide synthase (PKS) in place of the expected FAS C-terminal thioesterase used to off load fatty acid products. This new domain arrangement likely facilitates covalent transfer of steely N-terminal acyl products directly to the C-terminal type III PKS active sites, which catalyze both iterative polyketide extension and cyclization. The crystal structure of a steely C-terminal domain confirms conservation of the homodimeric type III PKS fold. These findings suggest new bioengineering strategies for expanding the scope of fatty acid and polyketide biosynthesis.
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Affiliation(s)
- Michael B Austin
- Howard Hughes Medical Institute, Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
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36
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Laporte C, Kosta A, Klein G, Aubry L, Lam D, Tresse E, Luciani MF, Golstein P. A necrotic cell death model in a protist. Cell Death Differ 2006; 14:266-74. [PMID: 16810325 DOI: 10.1038/sj.cdd.4401994] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
While necrotic cell death is attracting considerable interest, its molecular bases are still poorly understood. Investigations in simple biological models, taken for instance outside the animal kingdom, may benefit from less interference from other cell death mechanisms and from better experimental accessibility, while providing phylogenetic information. Can necrotic cell death occur outside the animal kingdom? In the protist Dictyostelium, developmental stimuli induced in an autophagy mutant a stereotyped sequence of events characteristic of necrotic cell death. This sequence included swift mitochondrial uncoupling with mitochondrial 2',7'-dichlorofluorescein diacetate fluorescence, ATP depletion and increased oxygen consumption. This was followed by perinuclear clustering of dilated mitochondria. Rapid plasma membrane rupture then occurred, which was evidenced by time-lapse videos and quantified by FACS. Of additional interest, developmental stimuli and classical mitochondrial uncouplers triggered a similar sequence of events, and exogenous glucose delayed plasma membrane rupture in a nonglycolytic manner. The occurrence of necrotic cell death in the protist Dictyostelium (1) provides a very favorable model for further study of this type of cell death, and (2) strongly suggests that the mechanism underlying necrotic cell death was present in an ancestor common to the Amoebozoa protists and to animals and has been conserved in evolution.
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Affiliation(s)
- C Laporte
- Centre d'Immunologie de Marseille-Luminy, Université de la Méditerranée, Case 906, Parc Scientifique de Luminy, 13288 Marseille Cedex 9, France
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37
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Serafimidis I, Kay RR. New prestalk and prespore inducing signals in Dictyostelium. Dev Biol 2005; 282:432-41. [PMID: 15950608 DOI: 10.1016/j.ydbio.2005.03.023] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2005] [Revised: 03/11/2005] [Accepted: 03/20/2005] [Indexed: 10/25/2022]
Abstract
The differentiation-inducing signals (DIFs) currently known in Dictyostelium appear unable to account for the full diversity of cell types produced in development. To search for new signals, we analyzed the differentiation in monolayers of cells expressing prestalk (ecmAO, ecmA, ecmO, ecmB and cAR2) and prespore (psA) markers. Expression of each marker drops off as the cell density is reduced, suggesting that cell interaction is required. Expression of each marker is inhibited by cerulenin, an inhibitor of polyketide synthesis, and can be restored by conditioned medium. However, the known stalk-inducing polyketide, DIF-1, could not replace conditioned medium and induce the ecmA or cAR2 prestalk markers, suggesting that they require different polyketide inducers. Polyketide production by fungi is stimulated by cadmium ions, which also dramatically stimulates differentiation in Dictyostelium cell cultures and the accumulation of medium factors. Factors produced with cadmium present were extracted from conditioned medium and fractionated by HPLC. A new factor inducing prespore cell differentiation, called PSI-2, and two inducing stalk cell differentiation (DIFs 6 and 7) were resolved. All are distinct from currently identified factors. DIF-6, but not DIF-7 or PSI-2, appears to have an essential carbonyl group. Thus Dictyostelium may use extensive polyketide signaling in its development.
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38
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Kosta A, Roisin-Bouffay C, Luciani MF, Otto GP, Kessin RH, Golstein P. Autophagy Gene Disruption Reveals a Non-vacuolar Cell Death Pathway in Dictyostelium. J Biol Chem 2004; 279:48404-9. [PMID: 15358773 DOI: 10.1074/jbc.m408924200] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Types of cell death include apoptosis, necrosis, and autophagic cell death. The latter can be defined as death of cells containing autophagosomes, autophagic bodies, and/or vacuoles. Are autophagy and vacuolization causes, consequences, or side effects in cell death with autophagy? Would control of autophagy suffice to control this type of cell death? We disrupted the atg1 autophagy gene in Dictyostelium discoideum, a genetically tractable model for developmental autophagic vacuolar cell death. The procedure that induced autophagy, vacuolization, and death in wild-type cells led in atg1 mutant cells to impaired autophagy and to no vacuolization, demonstrating that atg1 is required for vacuolization. Unexpectedly, however, cell death still took place, with a non-vacuolar and centrally condensed morphology. Thus, a cell death mechanism that does not require vacuolization can operate in this cell death model showing conspicuous vacuolization. The revelation of non-vacuolar cell death in this protist by autophagy gene disruption is reminiscent of caspase inhibition revealing necrotic cell death in animal cells. Thus, hidden alternative cell death pathways may be found across kingdoms and for diverse types of cell death.
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Affiliation(s)
- Artemis Kosta
- Centre d'Immunologie INSERM/CNRS/Université de la Mediterranée de Marseille-Luminy, Case 906, Avenue de Luminy, 13288 Marseille Cedex 9, France
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39
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Abraham J, Lemmers B, Hande MP, Moynahan ME, Chahwan C, Ciccia A, Essers J, Hanada K, Chahwan R, Khaw AK, McPherson P, Shehabeldin A, Laister R, Arrowsmith C, Kanaar R, West SC, Jasin M, Hakem R. Eme1 is involved in DNA damage processing and maintenance of genomic stability in mammalian cells. EMBO J 2004; 22:6137-47. [PMID: 14609959 PMCID: PMC275438 DOI: 10.1093/emboj/cdg580] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Yeast and human Eme1 protein, in complex with Mus81, constitute an endonuclease that cleaves branched DNA structures, especially those arising during stalled DNA replication. We identified mouse Eme1, and show that it interacts with Mus81 to form a complex that preferentially cleaves 3'-flap structures and replication forks rather than Holliday junctions in vitro. We demonstrate that Eme1-/- embryonic stem (ES) cells are hypersensitive to the DNA cross-linking agents mitomycin C and cisplatin, but only mildly sensitive to ionizing radiation, UV radiation and hydroxyurea treatment. Mammalian Eme1 is not required for the resolution of DNA intermediates that arise during homologous recombination processes such as gene targeting, gene conversion and sister chromatid exchange (SCE). Unlike Blm-deficient ES cells, increased SCE was seen only following induced DNA damage in Eme1-deficient cells. Most importantly, Eme1 deficiency led to spontaneous genomic instability. These results reveal that mammalian Eme1 plays a key role in DNA repair and the maintenance of genome integrity.
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Affiliation(s)
- Jacinth Abraham
- Advanced Medical Discovery Institute, Ontario Cancer Institute, 620 University Avenue, Suite 706, Toronto, Ontario M5G 2C1, Canada
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40
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Roisin-Bouffay C, Luciani MF, Klein G, Levraud JP, Adam M, Golstein P. Developmental cell death in dictyostelium does not require paracaspase. J Biol Chem 2003; 279:11489-94. [PMID: 14681218 DOI: 10.1074/jbc.m312741200] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Apoptotic cell death often requires caspases. Caspases are part of a family of related molecules including also paracaspases and metacaspases. Are molecules of this family generally involved in cell death? More specifically, do non-apoptotic caspase-independent types of cell death require paracaspases or metacaspases? Dictyostelium discoideum lends itself well to answering these questions because 1) it undergoes non-apoptotic developmental cell death of a vacuolar autophagic type and 2) it bears neither caspase nor metacaspase genes and apparently only one paracaspase gene. This only paracaspase gene can be inactivated by homologous recombination. Paracaspase-null clones were thus obtained in each of four distinct Dictyostelium strains. These clones were tested in two systems, developmental stalk cell death in vivo and vacuolar autophagic cell death in a monolayer system mimicking developmental cell death. Compared with parent cells, all of the paracaspase-null cells showed unaltered cell death in both test systems. In addition, paracaspase inactivation led to no alteration in development or interaction with a range of bacteria. Thus, in Dictyostelium, vacuolar programmed cell death in development and in a monolayer model in vitro would seem not to require paracaspase. To our knowledge, this is the first instance of developmental programmed cell death shown to be independent of any caspase, paracaspase or metacaspase. These results have implications as to the relationship in evolution between cell death and the caspase family.
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Affiliation(s)
- Céline Roisin-Bouffay
- Centre d'Immunologie de Marseille-Luminy, INSERM-CNRS-Universite de la Méditerranie, Parc Scientifique de Luminy, Case 906, 13288 Marseille Cedex 9, France
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41
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Zhang Y, Morrone G, Zhang J, Chen X, Lu X, Ma L, Moore M, Zhou P. CUL-4A stimulates ubiquitylation and degradation of the HOXA9 homeodomain protein. EMBO J 2003; 22:6057-67. [PMID: 14609952 PMCID: PMC275435 DOI: 10.1093/emboj/cdg577] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2002] [Revised: 09/10/2003] [Accepted: 09/25/2003] [Indexed: 12/11/2022] Open
Abstract
The HOXA9 homeodomain protein is a key regulator of hematopoiesis and embryonic development. HOXA9 is expressed in primitive hematopoietic cells, and its prompt downregulation is associated with myelocytic maturation. Although transcriptional inactivation of HOXA9 during hematopoietic differentiation has been established, little is known about the biochemical mechanisms underlying the subsequent removal of HOXA9 protein. Here we report that the CUL-4A ubiquitylation machinery controls the stability of HOXA9 by promoting its ubiquitylation and proteasome-dependent degradation. The homeodomain of HOXA9 is responsible for CUL-4A-mediated degradation. Interfering CUL-4A biosynthesis by ectopic expression or by RNA-mediated interference resulted in alterations of the steady-state levels of HOXA9, mirrored by impairment of the ability of 32D myeloid progenitor cells to undergo proper terminal differentiation into granulocytes. These results revealed a novel regulatory mechanism of hematopoiesis by ubiquitin-dependent proteolysis.
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Affiliation(s)
- Yue Zhang
- Department of Pathology and Laboratory Medicine, Weill Medical College and Graduate School of Medical Sciences of Cornell University, 1300 York Avenue, New York, NY 10021, USA
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42
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Golstein P, Aubry L, Levraud JP. Cell-death alternative model organisms: why and which? Nat Rev Mol Cell Biol 2003; 4:798-807. [PMID: 14570057 DOI: 10.1038/nrm1224] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Classical model organisms have helped greatly in our understanding of cell death but, at the same time, might have constrained it. The use of other, non-classical model organisms from all biological kingdoms could reveal undetected molecular pathways and better-defined morphological types of cell death. Here we discuss what is known and what might be learned from these alternative model systems.
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Affiliation(s)
- Pierre Golstein
- Pierre Golstein, Centre d'Immunologie de Marseille-Luminy, CNRS-INSERM-l'Université de la Mediteranée, Parc Scientifique de Luminy, Case 906, 13288 Marseille cedex 9, France.
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43
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Lefkir Y, de Chassey B, Dubois A, Bogdanovic A, Brady RJ, Destaing O, Bruckert F, O'Halloran TJ, Cosson P, Letourneur F. The AP-1 clathrin-adaptor is required for lysosomal enzymes sorting and biogenesis of the contractile vacuole complex in Dictyostelium cells. Mol Biol Cell 2003; 14:1835-51. [PMID: 12802059 PMCID: PMC165081 DOI: 10.1091/mbc.e02-10-0627] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2002] [Revised: 11/20/2002] [Accepted: 12/27/2002] [Indexed: 01/04/2023] Open
Abstract
Adaptor protein complexes (AP) are major components of the cytoplasmic coat found on clathrin-coated vesicles. Here, we report the molecular and functional characterization of Dictyostelium clathrin-associated AP-1 complex, which in mammalian cells, participates mainly in budding of clathrin-coated vesicles from the trans-Golgi network (TGN). The gamma-adaptin AP-1 subunit was cloned and shown to belong to a Golgi-localized 300-kDa protein complex. Time-lapse analysis of cells expressing gamma-adaptin tagged with the green-fluorescent protein demonstrates the dynamics of AP-1-coated structures leaving the Golgi apparatus and rarely moving toward the TGN. Targeted disruption of the AP-1 medium chain results in viable cells displaying a severe growth defect and a delayed developmental cycle compared with parental cells. Lysosomal enzymes are constitutively secreted as precursors, suggesting that protein transport between the TGN and lysosomes is defective. Although endocytic protein markers are correctly localized to endosomal compartments, morphological and ultrastructural studies reveal the absence of large endosomal vacuoles and an increased number of small vacuoles. In addition, the function of the contractile vacuole complex (CV), an osmoregulatory organelle is impaired and some CV components are not correctly targeted.
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Affiliation(s)
- Yaya Lefkir
- Institut de Biologie et Chimie des Protéines, UMR5086, CNRS/Université Lyon I, IFR 128 BioSciences Lyon-Gerland, 7, Passage du Vercors, France
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44
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Levraud JP, Adam M, Luciani MF, de Chastellier C, Blanton RL, Golstein P. Dictyostelium cell death: early emergence and demise of highly polarized paddle cells. J Cell Biol 2003; 160:1105-14. [PMID: 12654899 PMCID: PMC2172757 DOI: 10.1083/jcb.200212104] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Cell death in the stalk of Dictyostelium discoideum, a prototypic vacuolar cell death, can be studied in vitro using cells differentiating as a monolayer. To identify early events, we examined potentially dying cells at a time when the classical signs of Dictyostelium cell death, such as heavy vacuolization and membrane lesions, were not yet apparent. We observed that most cells proceeded through a stereotyped series of differentiation stages, including the emergence of "paddle" cells showing high motility and strikingly marked subcellular compartmentalization with actin segregation. Paddle cell emergence and subsequent demise with paddle-to-round cell transition may be critical to the cell death process, as they were contemporary with irreversibility assessed through time-lapse videos and clonogenicity tests. Paddle cell demise was not related to formation of the cellulose shell because cells where the cellulose-synthase gene had been inactivated underwent death indistinguishable from that of parental cells. A major subcellular alteration at the paddle-to-round cell transition was the disappearance of F-actin. The Dictyostelium vacuolar cell death pathway thus does not require cellulose synthesis and includes early actin rearrangements (F-actin segregation, then depolymerization), contemporary with irreversibility, corresponding to the emergence and demise of highly polarized paddle cells.
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Affiliation(s)
- Jean-Pierre Levraud
- Centre d'Immunologie de Marseille-Luminy, INSERM/CNRS, Case 906, Parc Scientifique de Luminy, 13288 Marseille Cedex 9, France
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45
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Zhang N, Long Y, Devreotes PN. Ege A, a novel C2 domain containing protein, is essential for GPCR-mediated gene expression in dictyostelium. Dev Biol 2002; 248:1-12. [PMID: 12142016 DOI: 10.1006/dbio.2002.0715] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During early stages of development, expression of aggregative genes in Dictyostelium is regulated by G protein-linked signaling pathways. We have isolated an aggregation-deficient mutant from a restriction enzyme-mediated insertional mutagenesis screen and have obtained its cDNA. Since the mutant expresses prestarvation genes but fails to express early genes, such as cAR1 and GP80, during development, we designated it early gene expression A (ege A). Ege A, encoding a cytosolic protein of 26 kDa, along with Ege B, belongs to a novel C2 domain-containing gene family. While Ege A mRNA is expressed during the first 2 h of development, Ege B is expressed at later stages. Ege A is not directly required for either G protein-mediated actin polymerization or activation of adenylyl cyclase. Ege A overexpressing and ege A(-) cells display similar phenotypes, suggesting that an optimal level of Ege A is required for proper function. Constitutive expression of a fully functional cAR1-YFP enables ege A(-) cells to form loose aggregates, but cAR1-YFP/ege A(-) cells are still unable to express GP80, suggesting that losses of gene expression were not solely due to a lack of cAR1. Overexpression of PKAcat, the constitutively active subunit of PKA, does not rescue the ege A(-) phenotype, suggesting that PKA is not located downstream from Ege A in the signaling pathway. We propose that Ege A is a novel cytosolic component required by early gene expression.
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MESH Headings
- Adenylyl Cyclases/metabolism
- Amino Acid Motifs
- Amino Acid Sequence
- Animals
- Blotting, Northern
- Blotting, Southern
- Blotting, Western
- Cyclic AMP/metabolism
- Cyclic AMP-Dependent Protein Kinases/metabolism
- Cytosol/metabolism
- DNA, Complementary/metabolism
- Dictyostelium/metabolism
- GTP-Binding Proteins/metabolism
- Gene Expression Regulation
- Genes, Dominant
- Microscopy, Confocal
- Microscopy, Fluorescence
- Molecular Sequence Data
- Mutation
- Phenotype
- Plasmids/metabolism
- Protein Structure, Tertiary
- Receptors, Cell Surface/metabolism
- Sequence Homology, Amino Acid
- Signal Transduction
- Time Factors
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Affiliation(s)
- Ning Zhang
- Department of Cell Biology and Anatomy, Johns Hopkins University of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA
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46
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Adam M, Levraud JP, Golstein P. Approches génétiques de la mort cellulaire programmée : succès et questions. Med Sci (Paris) 2002. [DOI: 10.1051/medsci/20021889831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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47
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Zhang N, Long Y, Devreotes PN. Ggamma in dictyostelium: its role in localization of gbetagamma to the membrane is required for chemotaxis in shallow gradients. Mol Biol Cell 2001; 12:3204-13. [PMID: 11598203 PMCID: PMC60167 DOI: 10.1091/mbc.12.10.3204] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
G-protein-mediated signal transduction pathways play an essential role in the developmental program of the simple eukaryotic organism Dictyostelium discoideum. Database searches have yielded 11 Galpha-subunits, a single Gbeta-subunit, but no Ggamma-subunits. We report here the purification, cDNA isolation, and functional analysis of a Ggamma-subunit. Like Gbeta, the Ggamma appears to be unique and hybridization studies show that Ggamma and Gbeta are expressed in parallel during development. Species-wide sequence comparisons of Ggamma-subunits and gamma-like domains of RGS proteins reveal short stretches of highly conserved residues as well as the common CXXL motif at the COOH-terminal of Ggammas that target Gbetagammas to plasma membrane. Overexpression of a CSVL-deleted Ggamma (GgammaDelta) in wild-type cells shifts Gbetagamma to the cytosol and selectively impairs certain G-protein-mediated signal transduction pathways. These cells are able to respond to increments in the stimulus, but are unable to sense chemoattractant gradients. They neither move directionally nor recruit PH-domains to their leading edge. Thus, a full complement of membrane-tethered Gbetagamma is required for sensing shallow gradients, but is not essential for responses to increments in extracellular stimuli.
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Affiliation(s)
- N Zhang
- Department of Cell Biology and Anatomy, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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48
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Abstract
We have constructed a mutant blocked in the biosynthesis of DIF-1, a chlorinated signal molecule proposed to induce differentiation of both major prestalk cell types formed during Dictyostelium development. Surprisingly, the mutant still forms slugs retaining one prestalk cell type, the pstA cells, and can form mature stalk cells. However, the other major prestalk cell type, the pstO cells, is missing. Normal pstO cell differentiation and their patterning in the slug are restored by development on a uniform concentration of DIF-1. We conclude that pstO and pstA cells are in fact induced by separate signals and that DIF-1 is the pstO inducer. Positional information, in the form of DIF-1 gradients, is evidently not required for pstO cell induction.
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Affiliation(s)
- C R Thompson
- MRC Laboratory of Molecular Biology, Cambridge CB2 2QH, England
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49
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Thompson CR, Kay RR. Cell-fate choice in Dictyostelium: intrinsic biases modulate sensitivity to DIF signaling. Dev Biol 2000; 227:56-64. [PMID: 11076676 DOI: 10.1006/dbio.2000.9877] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cell fate in Dictyostelium development depends on intrinsic differences between cells, dating from their growth period, and on cell interactions occurring during development. We have sought for a mechanism linking these two influences on cell fate. First, we confirmed earlier work showing that the vegetative differences are biases, not commitments, since cells that are stalky-biased when developed with one partner are sporey with another. Then we tested the idea that these biases operate by modulating the sensitivity of cells to the signals controlling cell fate during development. Cells grown without glucose are stalky-biased when developed with cells grown with glucose. We find, using monolayer culture conditions, that they are more sensitive to each of the stalk-inducing signals, DIFs 1-3. Mixing experiments show that this bias is a cell-intrinsic property. Cells initiating development early in the cell cycle are stalky compared to those initiating development later in the cycle. Likewise, they are more sensitive to DIF-1. Assays of standard markers for prestalk and prespore cell differentiation reveal similar differences in DIF-1 sensitivity between biased cells; DIF-1 dechlorinase (an early prestalk cell marker enzyme) behaves in a consistent manner. We propose that cell-fate biases are manifest as differences in sensitivity to DIF.
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Affiliation(s)
- C R Thompson
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 2QH, England
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Traynor D, Milne JL, Insall RH, Kay RR. Ca(2+) signalling is not required for chemotaxis in Dictyostelium. EMBO J 2000; 19:4846-54. [PMID: 10970875 PMCID: PMC302083 DOI: 10.1093/emboj/19.17.4846] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2000] [Revised: 07/19/2000] [Accepted: 07/19/2000] [Indexed: 11/14/2022] Open
Abstract
Dictyostelium cells can move rapidly towards a source of cyclic-AMP (cAMP). This chemoattractant is detected by G-protein-linked receptors, which trigger a signalling cascade including a rapid influx of Ca(2+). We have disrupted an inositol 1,4,5-trisphosphate (InsP(3)) receptor-like gene, iplA, to produce null cells in which Ca(2+) entry in response to chemoattractants is abolished, as is the normal increase in free cytosolic Ca(2+) ([Ca(2+)](c)) that follows chemotactic stimulation. However, the resting [Ca(2+)](c) is similar to wild type. This mutant provides a test for the role of Ca(2+) influx in both chemotaxis and the signalling cascade that controls it. The production of cyclic-GMP and cAMP, and the activation of the MAP kinase, DdERK2, triggered from the cAMP receptor, are little perturbed in the mutant; mobilization of actin into the cytoskeleton also follows similar kinetics to wild type. Mutant cells chemotax efficiently towards cAMP or folic acid and their sensitivity to cAMP is similar to wild type. Finally, they move at similar speeds to wild-type cells, with or without chemoattractant. We conclude that Ca(2+) signalling is not necessary for chemotaxis to cAMP.
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Affiliation(s)
- D Traynor
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH and School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
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