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Developmental Genetics 1991
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Developmental Biology (New York, N.Y. :... 1986We have described in D. discoideum a highly organized cell aggregation that is mediated by cAMP. After suitable differentiation induced by starvation, the cells develop... (Review)
Review
We have described in D. discoideum a highly organized cell aggregation that is mediated by cAMP. After suitable differentiation induced by starvation, the cells develop the capacity to orient in gradients of cAMP and to secrete cAMP in response to cAMP. This signaling response sets up the cell-cell relay of cAMP waves that transiently orients the cells toward the center. Both the signaling response and the chemotactic response, measured in isolated cells, adapt. The kinetics and properties of adaptation of the two responses are similar and may be due to the same mechanism. The mechanism does not involve protein synthesis, a change in the number or affinity of surface receptors, or the activation of adenylate cyclase. Adaptation of signaling is essential for the oscillatory production of cAMP at the aggregation centers and ensures that the cAMP waves move steadily toward the edge of the aggregation territories. Adaptation of the chemotactic response also ensures that cells do not reorient away from the center in the gradient presented by the trailing edge of the wave. We have demonstrated that both chemotaxis and cAMP signaling are mediated by the same surface receptor. The polypeptide containing the binding site of the receptor has been identified by photoaffinity labeling with [32P]-8-N3-cAMP as a diffuse band of 41,000-45,000 Mr. The receptor and adenylate cyclase copurify on a homogeneous class of vesicles resistant to extraction by nonionic detergents. A GTP-binding protein that is a substrate for cholera toxin-catalyzed ADP ribosylation is found in supernatants and membranes and may be similar to the Gs regulatory protein of adenylate cyclase in higher organisms. The mechanism of activation of the adenylate cyclase and chemotactic machinery is unknown. We have been able to inhibit the activation of the adenylate cyclase selectively and rapidly with agents acting to crosslink cell surface components, which may give a clue to the activation mechanism. The elaborate mechanisms of cell-cell communication occurring in D. discoideum are without precedent in biological literature, although models of oscillatory wave propagation have been proposed to account for pattern formation. Although it is unlikely that extracellular cAMP would be involved, it is not inconceivable that such mechanisms occur during the development of more evolutionarily advanced organisms. The organized communication system in D. discoideum is only apparent when cells are plated uniformly on a flat surface; such organized movements occurring in a three-dimensional structure such as an embryo would be very difficult to discern.
Topics: Cyclic AMP; Dictyostelium; GTP-Binding Proteins; Second Messenger Systems
PubMed: 2855927
DOI: 10.1007/978-1-4684-5050-7_13 -
Cellular Signalling Aug 2008Chemotaxis, the directional movement towards a chemical compound, is an essential property of many cells and has been linked to the development and progression of many... (Review)
Review
Chemotaxis, the directional movement towards a chemical compound, is an essential property of many cells and has been linked to the development and progression of many diseases. Eukaryotic chemotaxis is a complex process involving gradient sensing, cell polarity, remodelling of the cytoskeleton and signal relay. Recent studies in the model organism Dictyostelium discoideum have shown that chemotaxis does not depend on a single molecular mechanism, but rather depends on several interconnecting pathways. Surprisingly, small G-proteins appear to play essential roles in all these pathways. This review will summarize the role of small G-proteins in Dictyostelium, particularly highlighting the function of the Ras subfamily in chemotaxis.
Topics: Animals; Chemotaxis; Dictyostelium; Signal Transduction; rap GTP-Binding Proteins; ras Proteins
PubMed: 18385017
DOI: 10.1016/j.cellsig.2008.02.006 -
Microbiology (Reading, England) Mar 2021The social amoeba is a versatile organism that is unusual in alternating between single-celled and multi-celled forms. It possesses highly-developed systems for cell...
The social amoeba is a versatile organism that is unusual in alternating between single-celled and multi-celled forms. It possesses highly-developed systems for cell motility and chemotaxis, phagocytosis, and developmental pattern formation. As a soil amoeba growing on microorganisms, it is exposed to many potential pathogens; it thus provides fruitful ways of investigating host-pathogen interactions and is emerging as an influential model for biomedical research.
Topics: Biomedical Research; Cell Movement; Chemotaxis; Dictyostelium; Genome, Protozoan; Host-Pathogen Interactions; Models, Biological; Phylogeny
PubMed: 33646931
DOI: 10.1099/mic.0.001040 -
Development, Growth & Differentiation May 2011From microbes to metazoans, it is now clear that fluctuations in the abundance of mRNA transcripts and protein molecules enable genetically identical cells to oscillate... (Review)
Review
From microbes to metazoans, it is now clear that fluctuations in the abundance of mRNA transcripts and protein molecules enable genetically identical cells to oscillate between several distinct states (Kaern et al. 2005). Since this cell-cell variability does not derive from physical differences in the genetic code it is termed non-genetic heterogeneity. Non-genetic heterogeneity endows cell populations with useful capabilities they could never achieve if each cell were the same as its neighbors (Raj & van Oudenaarden 2008; Eldar & Elowitz 2010). One such example is seen during multicellular development and "salt and pepper" cell type differentiation. In this review, we will first examine the importance of non-genetic heterogeneity in initiating "salt and pepper" pattern formation during Dictyostelium discoideum development. Second, we will discuss the various ways in which non-genetic heterogeneity might be generated, as well as recent advances in understanding the molecular basis of heterogeneity in this system.
Topics: Cell Lineage; Dictyostelium; Genetic Heterogeneity
PubMed: 21585359
DOI: 10.1111/j.1440-169X.2011.01270.x -
Cell Biochemistry and Function Dec 2023Nutrient-sensing plays a crucial role in maintaining cellular energy and metabolic homeostasis. Perturbations in sensing pathways are associated with a wide variety of...
Nutrient-sensing plays a crucial role in maintaining cellular energy and metabolic homeostasis. Perturbations in sensing pathways are associated with a wide variety of pathologies, especially metabolic diseases. Very little is understood about sensing fluctuations in nutrients and how this information is integrated into physiological and metabolic adaptation that could further affect cell-fate decisions during differentiation in Dictyostelium discoideum (henceafter, Dictyostelium). Glucose is the primary metabolic fuel among all nutrients. Carbohydrates, lipids and proteins ultimately breakdown into glucose, which is further used for providing energy. The maintenance of optimum glucose levels is important for efficient cell-survival. Glucose is not only a nutrient, but also a signaling molecule influencing cell growth and differentiation in Dictyostelium. Modulation of endogenous glucose levels either by varying exogenous glucose levels or genetic overexpression or deletion of genes involved in glucose signaling lead to changes in endogenous metabolite levels such as ADP/ATP ratio, NAD /NADH ratio, cAMP and ROS levels which further influence cell-fate decisions. Here, we show that AMPKα and Sir2D are components of glucose-signaling pathway in Dictyostelium which adjust cell metabolism interdependently in response to nutrient-status and promote cell-fate decisions.
Topics: Dictyostelium; Signal Transduction; Cell Differentiation; Cell Cycle; Glucose
PubMed: 38014740
DOI: 10.1002/cbf.3892 -
Methods in Molecular Biology (Clifton,... 2006The Dictyostelium discoideum genome has been sequenced, assembled and annotated to a high degree of reliability. The parts-list of proteins and RNA encoded by the six... (Review)
Review
The Dictyostelium discoideum genome has been sequenced, assembled and annotated to a high degree of reliability. The parts-list of proteins and RNA encoded by the six chromosomes can now be accessed and analyzed. One of the initial surprises was the remarkably large number of genes that are shared with plants, animals, and fungi that must have been present in their common progenitor over a billion years ago. The genome encodes a total of about 10,300 proteins including protein families involved in cytoskeletal control, posttranslational protein modification, detoxification, secondary metabolism, cell adhesion, and signal transduction. The genome has a higher proportion of homopolymeric tracts and simple sequence repeats, such as [CAA]n, than most other genomes. Triplet repeats in translated regions produce the highest known proportion of polyglutamine tracts in any known proteome. Phylogenetic analyses based on complete proteomes confirm that the amoebozoa are a sister group to the animals and fungi, distinct from plants and early diverging species such as Leishmania, Plasmodium, or Giardia. The completed Dictyostelium sequence opens the door to large-scale functional exploration of its genome.
Topics: Animals; Chromosomes; Dictyostelium; Genome, Protozoan; Phylogeny; Proteome; Transcription, Genetic
PubMed: 16957282
DOI: 10.1385/1-59745-144-4:15 -
Development, Growth & Differentiation Dec 2000The cellular slime mold Dictyostelium discoideum is a fascinating organism, not only for biologists, but also for physicists. Since the Belousov-Zhabotinskii reaction... (Review)
Review
The cellular slime mold Dictyostelium discoideum is a fascinating organism, not only for biologists, but also for physicists. Since the Belousov-Zhabotinskii reaction pattern, a well-known non-linear phenomenon in chemistry, was observed during aggregation of Dictyostelium amoebae, Dictyostelium has been one of the major subjects of non-linear dynamics studies. Macroscopic theory, such as continuous cell density approximation, has been a common approach to studying pattern formation since the pioneering work of Turing. Recently, promising microscopic approaches, such as the cellular dynamics method, have emerged. They have shown that Dictyostelium is useful as a model system in biology, The synchronization mechanism of oscillatory production of cyclic adenosine 3',5'-monophosphate in Dictyostelium is discussed in detail to show how it is a universal feature that can explain synchronization in other organisms.
Topics: Animals; Cell Movement; Dictyostelium; Ligands; Models, Biological; Receptors, Cyclic AMP
PubMed: 11142676
DOI: 10.1046/j.1440-169x.2000.00547.x -
Current Opinion in Microbiology Dec 2003Cell polarity is essential for unicellular and multicellular stages of Dictyostelium development. Chemotaxis during early development requires each cell to rapidly... (Review)
Review
Cell polarity is essential for unicellular and multicellular stages of Dictyostelium development. Chemotaxis during early development requires each cell to rapidly reorganize its cytoskeleton to point towards a source of cAMP. This involves a balance between local induction of F-actin polymerization and suppression of pseudopods that point in other directions. Both the lipid phosphatidylinositol (3,4,5) trisphosphate and the soluble signal cGMP have been implicated in these processes, in addition to conserved and novel proteins. During later development cells adopt newly discovered, alternative modes of movement and interact through adhesion molecules. Finally, cells polarize secretion to particular regions of their surface.
Topics: Animals; Cell Polarity; Dictyostelium
PubMed: 14662359
DOI: 10.1016/j.mib.2003.10.008 -
Developmental Biology Dec 1999A key step in the development of all multicellular organisms is the differentiation of specialized cell types. The eukaryotic microorganism Dictyostelium discoideum... (Review)
Review
A key step in the development of all multicellular organisms is the differentiation of specialized cell types. The eukaryotic microorganism Dictyostelium discoideum provides a unique experimental system for studying cell-type determination and spatial patterning in a developing multicellular organism. Unlike metazoans, which become multicellular by undergoing many rounds of cell division after fertilization of an egg, the social amoeba Dictyostelium achieves multicellularity by the aggregation of approximately 10(5) cells in response to nutrient depletion. Following aggregation, cell-type differentiation and morphogenesis result in a multicellular organism with only a few cell types that exhibit a defined patterning along the anterior-posterior axis of the organism. Analysis of the mechanisms that control these processes is facilitated by the relative simplicity of Dictyostelium development and the availability of molecular, genetic, and cell biological tools. Interestingly, analysis has shown that many molecules that play integral roles in the development of higher eukaryotes, such as PKA, STATs, and GSK-3, are also essential for cell-type differentiation and patterning in Dictyostelium. The role of these and other signaling pathways in the induction, maintenance, and patterning of cell types during Dictyostelium development is discussed.
Topics: Animals; Cell Aggregation; Dictyostelium; Gene Expression Regulation, Developmental; Morphogenesis; Signal Transduction
PubMed: 10642783
DOI: 10.1006/dbio.1999.9485