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Ngo T, Miao X, Robinson DN, Zhou QQ. An RNA-binding protein, RNP-1, protects microtubules from nocodazole and localizes to the leading edge during cytokinesis and cell migration in Dictyostelium cells. Acta Pharmacol Sin 2016; 37:1449-1457. [PMID: 27569394 DOI: 10.1038/aps.2016.57] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 03/21/2016] [Indexed: 01/02/2023] Open
Abstract
AIM RNA-binding proteins are a large group of regulators (800-1000 in humans), some of which play significant roles in mRNA local translation. In this study, we analyzed the functions of the protein RNP-1, which was previously discovered in a genetic selection screen for nocodazole suppression. METHODS The growth rates and the microtubule networks of Dictyostelium cells were assessed with or without nocodazole (10 μmol/L) in suspension culture. Fluorescent images of RNP-1-GFP and RFP-tubulin were captured when cells were undergoing cytokinesis, then the GFP signal intensity and distance to the nearest centrosome were analyzed by using a computer program written in Matlab®. The RNP-1-GFP-expresseding cells were polarized, and the time-lapse images of cells were captured when cells were chemotaxing to a cAMP source. RESULTS Over-expression of RNP-1 rescued the growth defects caused by the microtubule-destabilizing agent nocodazole. Over-expression of RNP-1 protected microtubules from nocodazole treatment. In cells undergoing cytokinesis, the RNP-1 protein was localized to the polar regions of the cell cortex, and protein levels decreased proportionally as the power of the distance from the cell cortex to the nearest centrosome. In chemotactic cells, the RNP-1 protein localized to the leading edge of moving cells. Sequence analysis revealed that RNP-1 has two RNA-binding domains and is related to cytosolic poly(A)-binding proteins (PABPCs) in humans. CONCLUSION RNP-1 has roles in protecting microtubules and in directing cortical movement during cytokinesis and cell migration in Dictyostelium cells. The sequence similarity of RNP-1 to human PABPCs suggests that PABPCs may have similar functions in mammalian cells, perhaps in regulating microtubule dynamics and functions during cortical movement in cytokinesis and cell migration.
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Tillner J, Nau H, Winckler T, Dingermann T. Evaluation of the Teratogenic Potential of Valproic Acid Analogues in Transgenic Dictyostelium discoideum Strains. Toxicol In Vitro 2012; 12:463-9. [PMID: 20654429 DOI: 10.1016/s0887-2333(98)00016-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/07/1998] [Indexed: 10/17/2022]
Abstract
Very early during the development of new pharmaceuticals toxicological tests are most important. In addition to acute and chronic toxicity tests, it is crucial to estimate the teratogenic potential of promising drugs. We established a simple biological test system based on the cellular slime mold Dictyostelium discoideum. Under certain environmental conditions single cells of D. discoideum aggregate and undergo a relatively simple cell differentiation program, leading to the formation of stalk and spore cells. Transgenic D. discoideum strains carrying the bacterial beta-galactosidase gene under the control of various developmentally regulated D. discoideum promoters were shown to be useful tools to test the teratogenic potential of valproic acid (VPA). This study describes the effects of the VPA analogues S-4-yn-VPA, R-4-yn-VPA, and 2-ethyl-4-pentynoic acid on the D. discoideum developmental system. The presence of S-4-yn-VPA during D. discoideum development resulted in a strong inhibition of spore cell differentiation, whereas stalk cell formation was less affected. The enantiomer R-4-yn-VPA as well as 2-ethyl-4-pentynoic acid had only moderate effects on D. discoideum development. The above results are consistent with data obtained in mammalian teratogenicity assays, and suggest that D. discoideum development should be investigated with a number of additional substances to provide a simple alternative for high throughput screenings of new drugs.
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Affiliation(s)
- J Tillner
- Institut fur Pharmazeutische Biologie, Universität Frankfurt/M. (Biozentrum), Marie-Curie-Strasse 9, D-60439 Frankfurt/M, Germany
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3
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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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4
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Hinas A, Söderbom F. Treasure hunt in an amoeba: non-coding RNAs in Dictyostelium discoideum. Curr Genet 2007; 51:141-59. [PMID: 17171561 DOI: 10.1007/s00294-006-0112-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2006] [Revised: 11/22/2006] [Accepted: 11/23/2006] [Indexed: 12/20/2022]
Abstract
The traditional view of RNA being merely an intermediate in the transfer of genetic information, as mRNA, spliceosomal RNA, tRNA, and rRNA, has become outdated. The recent discovery of numerous regulatory RNAs with a plethora of functions in biological processes has truly revolutionized our understanding of gene regulation. Tiny RNAs such as microRNAs and small interfering RNAs play vital roles at different levels of gene control. Small nucleolar RNAs are much more abundant than previously recognized, and new functions beyond processing and modification of rRNA have recently emerged. Longer non-coding RNAs (ncRNAs) can also have important regulatory roles in the cell, e.g., antisense RNAs that control their target mRNAs. The majority of these important findings arose from analyses in various model organisms. In this review, we focus on ncRNAs in the social amoeba Dictyostelium discoideum. This important genetically tractable model organism has recently received renewed attention in terms of discovery, regulation and functional studies of ncRNAs. Old and recent findings are discussed and put in context of what we today know about ncRNAs in other organisms.
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Affiliation(s)
- Andrea Hinas
- Department of Molecular Biology, Biomedical Center, Swedish University of Agricultural Sciences, Box 590, 75124 Uppsala, Sweden
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5
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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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6
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Chen G, Kuspa A. Prespore cell fate bias in G1 phase of the cell cycle in Dictyostelium discoideum. EUKARYOTIC CELL 2005; 4:1755-64. [PMID: 16215182 PMCID: PMC1265904 DOI: 10.1128/ec.4.10.1755-1764.2005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2005] [Accepted: 07/29/2005] [Indexed: 11/20/2022]
Abstract
By generating a population of Dictyostelium cells that are in the G1 phase of the cell cycle we have examined the influence of cell cycle status on cell fate specification, cell type proportioning and its regulation, and terminal differentiation. The lack of observable mitosis during the development of these cells and the quantification of their cellular DNA content suggests that they remain in G1 throughout development. Furthermore, chromosomal DNA synthesis was not detectable these cells, indicating that no synthesis phase had occurred, although substantial mitochondrial DNA synthesis did occur in prespore cells. The G1-phase cells underwent normal morphological development and sporulation but displayed an elevated prespore/prestalk ratio of 5.7 compared to the 3.0 (or 3:1) ratio normally observed in populations dominated by G2-phase cells. When migrating slugs produced by G1-phase cells were bisected, each half could reestablish the 5.7 (or 5.7:1) prespore/prestalk ratio. These results demonstrate that Dictyostelium cells can carry out the entire developmental cycle in the G1 phase of the cell cycle and that passage from G2 into G1 phase is not required for sporulation. Our results also suggest that the population asymmetry provided by the distribution of cells around the cell cycle at the time of starvation is not strictly required for cell type proportioning. Finally, when developed together with G2-phase cells, G1-phase cells preferentially become prespore cells and exclude G2-phase cells from the prespore-spore cell population, suggesting that G1-phase cells have an advantage over G2-phase cells in executing the spore cell differentiation pathway.
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Affiliation(s)
- Guokai Chen
- Verna and Mars McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA
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7
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Charette SJ, Cornillon S, Cosson P. Identification of low frequency knockout mutants in Dictyostelium discoideum created by single or double homologous recombination. J Biotechnol 2005; 122:1-4. [PMID: 16198440 DOI: 10.1016/j.jbiotec.2005.08.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2005] [Revised: 08/19/2005] [Accepted: 08/24/2005] [Indexed: 11/16/2022]
Abstract
Generation and characterization of knockout clones is a widely used approach to evaluate the specific function of a gene product in Dictyostelium discoideum. The mutant clones are generally obtained by double homologous recombination in the target gene. A frequent limitation to obtaining mutants is the low frequency of homologous recombination. Here we present an easy method to identify rare mutants, based on PCR analysis of pools of clones. This method also allows the isolation of functional knockout mutants created by a single homologous recombination event, which can be more frequent than a double recombination event.
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Affiliation(s)
- Steve J Charette
- Université de Genève, Centre Médical Universitaire, Département de Physiologie Cellulaire et Métabolisme, Switzerland.
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8
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Brodegger T, Stockmann A, Oberstrass J, Nellen W, Follmann H. Novel thioredoxin targets in Dictyostelium discoideum identified by two-hybrid analysis: interactions of thioredoxin with elongation factor 1alpha and yeast alcohol dehydrogenase. Biol Chem 2005; 385:1185-92. [PMID: 15653432 DOI: 10.1515/bc.2004.153] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Thioredoxins (Trx) are ubiquitous dicysteine proteins capable of modulating enzymes and other cellular targets through specific disulfide-dithiol redox changes. They are unique in that a large number of very diverse metabolic systems are addressed and redox-regulated in bacteria, animal, and plant cells, but the finite number of thioredoxin interaction partners is still unknown. Two-hybrid methodology should provide a rational way to establish thioredoxin functions in a given organism. We report a search for physiological target proteins of thioredoxin1 in the social amoeba Dictyostelium discoideum , which possesses three developmentally regulated thioredoxin genes, all of which lack functional characterisation. A two-hybrid approach identified at least seven bona fide thioredoxin partners, including oxidoreductases, proteins of the ribosomal translation apparatus, and the cytoskeletal protein filopodin. With the exception of ribonucleotide reductase, none of these systems had previously been linked to specific redox modulation. Molecular interactions in two of the new thioredoxin/target protein couples were verified by biochemical studies: (1) thioredoxin1 and the abundant elongation factor 1alpha from D. discoideum form the mixed heterodisulfide characteristic of the thioredoxin mechanism of action; and (2) reduced thioredoxin, but not glutathione, strongly inhibits yeast alcohol dehydrogenase catalysis of ethanol oxidation.
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Affiliation(s)
- Thomas Brodegger
- Department of Biochemistry, Natural Sciences Faculty, University of Kassel, D-34109 Kassel, Germany
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9
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Charette SJ, Cosson P. Preparation of genomic DNA from Dictyostelium discoideum for PCR analysis. Biotechniques 2004; 36:574-5. [PMID: 15088372 DOI: 10.2144/04364bm01] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Affiliation(s)
- Steve J Charette
- Université de Genève, Centre Médical Universitaire, Département de Physiologie Cellulaire et Métabolisme, 1 rue Michel Servet, CH-1211 Genève 4, Switzerland.
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10
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Chen G, Shaulsky G, Kuspa A. Tissue-specific G1-phase cell-cycle arrest prior to terminal differentiation in Dictyostelium. Development 2004; 131:2619-30. [PMID: 15128662 DOI: 10.1242/dev.01151] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The cell cycle status of developing Dictyostelium cells remains unresolved because previous studies have led to conflicting interpretations. We propose a new model of cell cycle events during development. We observe mitosis of about 50% of the cells between 12 and 18 hours of development. Cellular DNA content profiles obtained by flow cytometry and quantification of extra-chromosomal and chromosomal DNA suggest that the daughter cells have half the chromosomal DNA of vegetative cells. Furthermore, little chromosomal DNA synthesis occurs during development, indicating that no S phase occurs. The DNA content in cells sorted by fluorescent tissue-specific reporters indicates that prespore cells divide before prestalk cells and later encapsulate as G1-arrested spores. Consistent with this, germinating spores have one copy of their chromosomes, as judged by fluorescence in situ hybridization and they replicate their chromosomes before mitosis of the emergent amoebae. The DNA content of mature stalk cells suggests that they also attain a G1 state prior to terminal differentiation. As prestalk cells appear to be in G2 up to 22 hours of development, our data suggest that they divide just prior to stalk formation. Our results suggest tissue-specific regulation of G1 phase cell cycle arrest prior to terminal differentiation in Dictyostelium.
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Affiliation(s)
- Guokai Chen
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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11
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Nebl T, Kotsifas M, Schaap P, Fisher PR. Multiple signalling pathways connect chemoattractant receptors and calcium channels in Dictyostelium. J Muscle Res Cell Motil 2003; 23:853-65. [PMID: 12952083 DOI: 10.1023/a:1024496232604] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Dictyostelium mutants expressing aequorin were used to study and compare the roles of heterotrimeric G-proteins and the second messengers IP3 and cGMP in regulating folate- and cAMP receptor-activated [Ca2+]i signals. The calcium responses of vegetative cells to folate were dramatically impaired in Gbeta and Galpha4 null mutants but were restored with altered kinetics and temperature-sensitivity in Gbeta null mutants overexpressing wild type and temperature-sensitive Gbeta isoforms. Folic acid receptors thus mediate changes in [Ca2+]i via a Galpha4betagamma-dependent pathway. Neither folate nor cAMP-induced [Ca2+]i signals were significantly altered in PLC null transformants, but [Ca2+]i changes elicited by both attractants were significantly prolonged in two stmF mutants lacking cGMP-specific phosphodiesterase activity. This confirms an important role of cGMP in regulating receptor-activated Ca2+ uptake and/or extrusion systems. This cGMP-dependent part of the Ca2+ response to cAMP stimuli was developmentally down-regulated and all but disappeared by the time the cells reached full aggregation competence after 8 h of starvation. The results suggest that folate and cAMP receptor-activated [Ca2+]i signals are regulated in a complex manner via multiple signalling pathways, one that is G-protein- and cGMP-dependent (present at the vegetative and early poststarvation stage) and another that is G-protein-independent (dominant in fully aggregation-competent cells at approximately 8 h poststarvation).
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Affiliation(s)
- Thomas Nebl
- Department of Microbiology, La Trobe University, Bundoora, Victoria 3083, Australia
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12
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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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13
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Takeda K, Saito T, Tanaka T, Morio T, Maeda M, Tanaka Y, Ochiai H. A novel gene trap method using terminator-REMI and 3' rapid amplification of cDNA ends (RACE) in Dictyostelium. Gene 2003; 312:321-33. [PMID: 12909370 DOI: 10.1016/s0378-1119(03)00558-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We describe a novel restriction enzyme-mediated integration (REMI) method for gene trapping in Dictyostelium based on the use of a terminator-deficient vector. The vector has a blasticidin deaminase (bsr) gene as a selectable marker but lacks a terminator containing a poly(A) addition signal (AATAAA). Thus, the vector was expected to integrate into the coding region of a gene to create a fusion transcript flanked by the 3' proximal region of the trapped gene. The trapped gene can be identified by simply amplifying the fusion transcript by 3' rapid amplification of cDNA ends (3'-RACE). In the analysis of 35 integration events into known genes, the vectors were found to be integrated 20 times in close proximity to the 3' ends of the genes and in the direction of transcription. This strictly localized insertion seemed to be mediated by negative selection via the surveillance system referred to nonsense-mediated mRNA decay. In contrast, in 15 events the vector integrated in the opposite direction to transcription and at random positions throughout the coding sequence. Analysis of the trapped 3' sequences showed that the transcription of the fusion gene terminated prematurely without the apparent use of an endogenous terminator; nevertheless the transcript did exhibit a poly(A) tail. Based on these results, we designated the method terminator-REMI. Using this method, we have generated a library of tagged Dictyostelium clones from which we have thus far isolated 242 developmental mutants.
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Affiliation(s)
- Kosuke Takeda
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo, 060-0810, Hokkaido, Japan
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14
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Abstract
Endocytosis in protozoa is often regarded as largely different from the pathways operating in mammalian cells. Experiments in the amoeba Dictyostelium, one of the genetically tractable single-celled organisms, have allowed us to manipulate the flow through endocytic compartments and to study the dynamic distribution of molecules by means of green fluorescent protein fusions. This review attempts to compile the molecular data available from Dictyostelium and assign them to specific steps of internalization by phagocytosis or macropinocytosis and to subsequent stages of the endocytic pathway. Parallels to phagocytes of the mammalian immune system are emphasized. The major distinctive feature between mammalian phagocytes and free-living cells is the need for osmoregulation. Therefore Dictyostelium cells possess a contractile vacuole that has occasionally obscured analysis of endocytosis but is now found to be entirely separate from endocytic organelles. In conclusion, the potential of Dictyostelium amoebas to provide a model system of mammalian phagocytes is ever increasing.
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Affiliation(s)
- Markus Maniak
- Department of Cell Biology, Universitaet Kassel, 34109 Kassel, Germany
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15
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Cornillon S, Dubois A, Brückert F, Lefkir Y, Marchetti A, Benghezal M, De Lozanne A, Letourneur F, Cosson P. Two members of the beige/CHS (BEACH) family are involved at different stages in the organization of the endocytic pathway in Dictyostelium. J Cell Sci 2002; 115:737-44. [PMID: 11865029 DOI: 10.1242/jcs.115.4.737] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Proteins of the Chediak-Higashi/Beige (BEACH) family have been implicated in the function of lysosomes, as well as in signal transduction, but their molecular role is still poorly understood. In Dictyostelium, at least six members of the family can be identified. Here cells with mutations in two of these genes, LVSA and LVSB, were analyzed. Interestingly both mutants exhibited defects in the organization of the endocytic pathway,albeit at distinct stages. In lvsB mutant cells, the regulated secretion of lysosomal enzymes was enhanced, a phenotype reminiscent of the Chediak-Higashi syndrome. LvsA mutant cells exhibited alterations in the organization and function of the early endocytic and phagocytic pathway. The LvsA protein may participate in the signaling pathway, which links adhesion of a particle to the subsequent formation of a phagocytic cup. Further genetic analysis will be necessary to determine whether other members of the BEACH family of proteins are also involved in controlling the organization of the endocytic pathway.
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Affiliation(s)
- Sophie Cornillon
- Université de Genève, Centre Médical Universitaire, Département de morphologie, 1 Rue Michel Servet, CH1211 Genève 4, Switzerland
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16
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Levraud JP, Adam M, Cornillon S, Golstein P. Methods to study cell death in Dictyostelium discoideum. Methods Cell Biol 2002; 66:469-97. [PMID: 11396017 DOI: 10.1016/s0091-679x(01)66022-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- J P Levraud
- Centre d'Immunologie INSERM-CNRS de Marseille-Luminy 13288 Marseille Cedex 9, France
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17
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Winckler T, Trautwein C, Tschepke C, Neuhäuser C, Zündorf I, Beck P, Vogel G, Dingermann T. Gene function analysis by amber stop codon suppression: CMBF is a nuclear protein that supports growth and development of Dictyostelium amoebae. J Mol Biol 2001; 305:703-14. [PMID: 11162086 DOI: 10.1006/jmbi.2000.4341] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The C-module-binding factor, CMBF, is a nuclear DNA-binding protein which was originally identified through its specific binding to a promoter element within the retrotransposable element TRE5-A of Dictyostelium discoideum AX2 cells. In order to analyse putative physiological functions of CMBF for the TRE5-A-hosting D. discoideum cells, we used a novel strategy to create mutant cell lines which stably underexpressed functional CMBF. An amber (UAG) translation stop codon was introduced into the chromosomal copy of the CMBF-encoding gene (cbfA), and an amber suppressor tRNA gene was expressed in the same mutant cells. Due to the low efficiency of translation stop codon suppression in this system all recovered cell lines expressed <20 % of wild-type CMBF levels. The mutant cell lines displayed strong growth phenotypes when plated on their natural food source, bacteria. We show evidence that growth reduction was due to impaired phagocytosis of bacteria in the mutants. All obtained mutants showed a strong developmental defect which was defined by the formation of very small fruiting bodies. The strength of the developmental phenotype appeared to depend upon the residual CMBF levels maintained in the mutants. We propose that CMBF is a general transcription regulator which supports the normal expression of several genes required for the maintenance of high proliferation rates of D. discoideum amoebae as well as proper aggregation and development. Our results demonstrate that amber stop codon suppression may be a useful strategy to stably underexpress proteins whose coding genes cannot be successfully disrupted by homologous recombination.
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Affiliation(s)
- T Winckler
- Institut für Pharmazeutische Biologie, Universität Frankfurt/M. (Biozentrum), D-60439 Frankfurt am Main, Germany.
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18
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Sucgang R, Shaulsky G, Kuspa A. Toward the functional analysis of the Dictyostelium discoideum genome. J Eukaryot Microbiol 2000; 47:334-9. [PMID: 11140446 DOI: 10.1111/j.1550-7408.2000.tb00058.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Dictyostelium discoideum is a useful model for molecular studies of cell biology and development. The 34-megabase Dictyostelium genome is currently being sequenced through the efforts of an international consortium. The genome is expected to encode 8-10,000 genes, including all those required for a free-living eukaryote capable of multicellular development. A complete description of the Dictyostelium genome will open the way toward the application of genome-based experimental approaches to studies of cell biology and development in this organism, and allow detailed physiological and evolutionary comparisons to other species.
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Affiliation(s)
- R Sucgang
- Department of Biochemistry, Baylor College of Medicine, Houston, Texas 77030, USA
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Koonce MP, Knecht DA. Cytoplasmic dynein heavy chain is an essential gene product in Dictyostelium. CELL MOTILITY AND THE CYTOSKELETON 2000; 39:63-72. [PMID: 9453714 DOI: 10.1002/(sici)1097-0169(1998)39:1<63::aid-cm6>3.0.co;2-h] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We describe here three different approaches to perturb cytoplasmic dynein heavy chain (DHC) gene function in Dictyostelium: integration of a marker into the heavy chain coding sequence by homologous recombination to disrupt transcription, expression of antisense RNA to inhibit translation, and expression of a 158 kDa amino-terminal coding region to perturb the native protein organization. By homologous recombination, we fail to obtain cells that lack an intact DHC gene product. Cells containing antisense orientation plasmids (but not sense) appear to die 4 to 6 days following transformation. Plasmids designed to overexpress an amino-terminal region of the DHC result in substantially reduced transformation efficiency. When expressed at low levels, the truncated amino-terminal product appears capable of dimerizing with an intact heavy chain or with itself, essentially producing a cargo-binding domain lacking mechanochemical activity. This, in turn, likely competes with the native protein's function. These three approaches taken together indicate that the dynein heavy chain is an essential gene in Dictyostelium.
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Affiliation(s)
- M P Koonce
- Division of Molecular Medicine, Wadsworth Center, Albany, New York 12201-0509, USA.
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Abstract
The third Siena proteomics conference held August 31-September 4, 1998, heralded a change in emphasis from technology development to using proteomics to assist in resolving biological questions. In this review, proteomics is placed in context with other major influences in the way discovery research is conducted in biology. The current status of genomics is examined in its broadest sense, including how such studies may influence the development of proteomics. It is suggested that we are entering a new phase in biology where information is no longer limiting and integration of different technologies is required to attack the big problems of biology. While much of the focus of funding bodies, both in the public and private sector, is on practical outcomes (new drugs, etc.), the new technologies are equally amenable to attacking long-standing fundamental challenges, such as cell division, cell patterning and morphogenesis.
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Affiliation(s)
- K L Williams
- Proteome Systems, North Ryde, Sydney, NSW, Australia.
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Fey P, Cox EC. Gene trapping with GFP: the isolation of developmental mutants in the slime mold Polysphondylium. Curr Biol 1997; 7:909-12. [PMID: 9382807 DOI: 10.1016/s0960-9822(06)00384-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In order to study how a cell mass undergoes a transition from one symmetry to another in the slime mold Polysphondylium, we developed a genetic screen in which mutant phenotype and gene expression can easily be visualized in the living organism. The screen combines restriction enzyme-mediated integration (REMI) [1,2] and green fluorescent protein (GFP) [3] expression. In REMI, a restriction enzyme is electroporated along with linearized vector into cells, thus determining the site of plasmid insertion and often increasing the integration frequency. A set of transforming plasmids carrying the GFP coding sequence in three reading frames was used for transformation. The plasmids were constructed so that GFP could be expressed only under control of a host promoter. Living transformants expressing GFP spatially and temporally could be rapidly identified in a very large background of non-expressing cells and fruiting bodies. The phenotypes of representative mutants range from cells that cannot aggregate and initiate cell-cell interactions, through mutant fruiting bodies, to apparently wild-type fruiting bodies expressing GFP in all or a subpopulation of cells. The ability to screen mutant living cells and tissues for GFP expression is rapid and effective and likely to have application in many transformable systems where screening by gene and promoter trapping is essential for understanding temporal and spatial gene regulation.
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Affiliation(s)
- P Fey
- Department of Molecular Biology, Princeton University, New Jersey 08544, USA
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Dammann H, Hellstern S, Husain Q, Mutzel R. Primary structure, expression and developmental regulation of a Dictyostelium calcineurin A homologue. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 238:391-9. [PMID: 8681950 DOI: 10.1111/j.1432-1033.1996.0391z.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
cDNA clones for the catalytic subunit of Ca2+/calmodulin(CaM)-dependent protein phosphatase (calcineurin A, protein phosphatase 2B) from Dictyostelium discoideum were isolated by functional screening of a lambda gt11 lysogen expression library with labeled Dictyostelium CaM. A complete cDNA of 2146 bp predicts a protein of 623 amino acids with homology to calcineurin A from other organisms and a similar molecular architecture. However, the Dictyostelium protein contains N-terminal and C-terminal extra domains causing a significantly higher molecular mass than found in any of its known counterparts. Recombinant Dictyostelium calcineurin A was purified from Escherichia coli cells and shown to display similar enzymatic properties as the enzyme from other sources. On Western blots specific antibodies against the protein recognized a band of approximately 80 kDa that migrated with an endogenous CaM-binding activity. Both the mRNA for calcineurin A and the protein are expressed during the growth phase. During early development the abundance of the protein is reduced and then increases to peak after 10 h of starvation, when tight aggregates have formed.
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Affiliation(s)
- H Dammann
- Fakultät für Biologie, Universität Konstanz, Germany
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