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Molecular Microbiology Jan 2023Mammalian professional phagocytic cells ingest and kill invading microorganisms and prevent the development of bacterial infections. Our understanding of the sequence of...
Mammalian professional phagocytic cells ingest and kill invading microorganisms and prevent the development of bacterial infections. Our understanding of the sequence of events that results in bacterial killing and permeabilization in phagosomes is still largely incomplete. In this study, we used the Dictyostelium discoideum amoeba as a model phagocyte to study the fate of the bacteria Klebsiella pneumoniae inside phagosomes. Our analysis distinguishes three consecutive phases: bacteria first lose their ability to divide (killing), then their cytosolic content is altered (permeabilization), and finally their DNA is degraded (digestion). Phagosomal acidification and production of free radicals are necessary for rapid killing, membrane-permeabilizing proteins BpiC and AlyL are required for efficient permeabilization. These results illustrate how a combination of genetic and microscopical tools can be used to finely dissect the molecular events leading to bacterial killing and permeabilization in a maturing phagosome.
Topics: Animals; Dictyostelium; Phagosomes; Klebsiella pneumoniae; Membrane Proteins; Bacteria; Mammals
PubMed: 36416195
DOI: 10.1111/mmi.15004 -
Cells Oct 2021Ketogenic diets, used in epilepsy treatment, are considered to work through reduced glucose and ketone generation to regulate a range of cellular process including...
Ketogenic diets, used in epilepsy treatment, are considered to work through reduced glucose and ketone generation to regulate a range of cellular process including autophagy induction. Recent studies into the medium-chain triglyceride (MCT) ketogenic diet have suggested that medium-chain fatty acids (MCFAs) provided in the diet, decanoic acid and octanoic acid, cause specific therapeutic effects independent of glucose reduction, although a role in autophagy has not been investigated. Both autophagy and MCFAs have been widely studied in , with findings providing important advances in the study of autophagy-related pathologies such as neurodegenerative diseases. Here, we utilize this model to analyze a role for MCFAs in regulating autophagy. We show that treatment with decanoic acid but not octanoic acid induces autophagosome formation and modulates autophagic flux in high glucose conditions. To investigate this effect, decanoic acid, but not octanoic acid, was found to induce the expression of autophagy-inducing proteins (Atg1 and Atg8), providing a mechanism for this effect. Finally, we demonstrate a range of related fatty acid derivatives with seizure control activity, 4BCCA, 4EOA, and Epilim (valproic acid), also function to induce autophagosome formation in this model. Thus, our data suggest that decanoic acid and related compounds may provide a less-restrictive therapeutic approach to activate autophagy.
Topics: Autophagosomes; Autophagy; Decanoic Acids; Dictyostelium; Phosphatidylinositol Phosphates; Proto-Oncogene Proteins c-akt
PubMed: 34831171
DOI: 10.3390/cells10112946 -
Scientific Reports Mar 2019Dictyostelium discoideum (D.d.) is a widely studied amoeba due to its capabilities of development, survival, and self-organization. During aggregation it produces and...
Dictyostelium discoideum (D.d.) is a widely studied amoeba due to its capabilities of development, survival, and self-organization. During aggregation it produces and relays a chemical signal (cAMP) which shows spirals and target centers. Nevertheless, the natural emergence of these structures is still not well understood. We present a mechanism for creation of centers and target waves of cAMP in D.d. by adding cell inhomogeneity to a well known reaction-diffusion model of cAMP waves and we characterize its properties. We show how stable activity centers appear spontaneously in areas of higher cell density with the oscillation frequency of these centers depending on their density. The cAMP waves have the characteristic dispersion relation of trigger waves and a velocity which increases with cell density. Chemotactically competent cells react to these waves and create aggregation streams even with very simple movement rules. Finally we argue in favor of the existence of bounded phosphodiesterase to maintain the wave properties once small cell clusters appear.
Topics: Chemotaxis; Computer Simulation; Cyclic AMP; Dictyostelium; Models, Biological; Movement; Phosphoric Diester Hydrolases; Protozoan Proteins; Signal Transduction
PubMed: 30850709
DOI: 10.1038/s41598-019-40373-4 -
Cells Feb 2019The neuronal ceroid lipofuscinoses (NCLs) are a group of devastating neurological disorders that have a global distribution and affect people of all ages. Commonly known... (Review)
Review
The neuronal ceroid lipofuscinoses (NCLs) are a group of devastating neurological disorders that have a global distribution and affect people of all ages. Commonly known as Batten disease, this form of neurodegeneration is linked to mutations in 13 genetically distinct genes. The precise mechanisms underlying the disease are unknown, in large part due to our poor understanding of the functions of NCL proteins. The social amoeba has proven to be an exceptional model organism for studying a wide range of neurological disorders, including the NCLs. The genome contains homologs of 11 of the 13 NCL genes. Its life cycle, comprised of both single-cell and multicellular phases, provides an excellent system for studying the effects of NCL gene deficiency on conserved cellular and developmental processes. In this review, we highlight recent advances in NCL research using as a biomedical model.
Topics: Dictyostelium; Humans; Models, Biological; Neuronal Ceroid-Lipofuscinoses; Osmoregulation; Phenotype; Protozoan Proteins; Tripeptidyl-Peptidase 1
PubMed: 30717401
DOI: 10.3390/cells8020115 -
Current Opinion in Genetics &... Aug 2016Dictyostelia represent a tractable system to resolve the evolution of cell-type specialization, with some taxa differentiating into spores only, and other taxa with... (Review)
Review
Dictyostelia represent a tractable system to resolve the evolution of cell-type specialization, with some taxa differentiating into spores only, and other taxa with additionally one or up to four somatic cell types. One of the latter forms, Dictyostelium discoideum, is a popular model system for cell biology and developmental biology with key signalling pathways controlling cell-specialization being resolved recently. For the most dominant pathways, evolutionary origins were retraced to a stress response in the unicellular ancestor, while modifications in the ancestral pathway were associated with acquisition of multicellular complexity. This review summarizes our current understanding of developmental signalling in D. discoideum and its evolution.
Topics: Animals; Cyclic AMP; Developmental Biology; Dictyostelium; Evolution, Molecular; Phylogeny; Signal Transduction; Stress, Physiological
PubMed: 27318097
DOI: 10.1016/j.gde.2016.05.014 -
Genes Mar 2021Multicellularity evolved repeatedly in the history of life, but how it unfolded varies greatly between different lineages. Dictyostelid social amoebas offer a good... (Comparative Study)
Comparative Study Review
Multicellularity evolved repeatedly in the history of life, but how it unfolded varies greatly between different lineages. Dictyostelid social amoebas offer a good system to study the evolution of multicellular complexity, with a well-resolved phylogeny and molecular genetic tools being available. We compare the life cycles of the Dictyostelids with closely related amoebozoans to show that complex life cycles were already present in the unicellular common ancestor of Dictyostelids. We propose frost resistance as an early driver of multicellular evolution in Dictyostelids and show that the cell signalling pathways for differentiating spore and stalk cells evolved from that for encystation. The stalk cell differentiation program was further modified, possibly through gene duplication, to evolve a new cell type, cup cells, in Group 4 Dictyostelids. Studies in various multicellular organisms, including Dictyostelids, volvocine algae, and metazoans, suggest as a common principle in the evolution of multicellular complexity that unicellular regulatory programs for adapting to environmental change serve as "proto-cell types" for subsequent evolution of multicellular organisms. Later, new cell types could further evolve by duplicating and diversifying the "proto-cell type" gene regulatory networks.
Topics: Amoeba; Biological Evolution; Cold Temperature; Dictyostelium; Evolution, Molecular; Life Cycle Stages; Phylogeny; Signal Transduction; Stress, Physiological
PubMed: 33801615
DOI: 10.3390/genes12040487 -
The International Journal of... 2019The Dictyostelium discoideum model system is a powerful tool for undergraduate cell biology teaching laboratories. The cells are biologically safe, grow at room...
The Dictyostelium discoideum model system is a powerful tool for undergraduate cell biology teaching laboratories. The cells are biologically safe, grow at room temperature and it is easy to experimentally induce, observe, and perturb a breadth of cellular processes making the system amenable to many teaching lab situations and goals. Here we outline the advantages of Dictyostelium, discuss laboratory courses we teach in three very different educational settings, and provide tips for both the novice and experienced Dictyostelium researcher. With this article and the extensive sets of protocols and tools referenced here, implementing these labs, or parts of them, will be relatively straightforward for any instructor.
Topics: Biology; California; Cell Adhesion; Cell Movement; Cell Proliferation; Chemotaxis; Connecticut; Cytoskeleton; Dictyostelium; Electroporation; Endocytosis; Folic Acid; Humans; Iowa; Models, Biological; Phagocytosis; Phototaxis; Students; Teaching; Universities
PubMed: 31840792
DOI: 10.1387/ijdb.190249dk -
PLoS Computational Biology Aug 2021Navigation of fast migrating cells such as amoeba Dictyostelium and immune cells are tightly associated with their morphologies that range from steady polarized forms... (Comparative Study)
Comparative Study
Navigation of fast migrating cells such as amoeba Dictyostelium and immune cells are tightly associated with their morphologies that range from steady polarized forms that support high directionality to those more complex and variable when making frequent turns. Model simulations are essential for quantitative understanding of these features and their origins, however systematic comparisons with real data are underdeveloped. Here, by employing deep-learning-based feature extraction combined with phase-field modeling framework, we show that a low dimensional feature space for 2D migrating cell morphologies obtained from the shape stereotype of keratocytes, Dictyostelium and neutrophils can be fully mapped by an interlinked signaling network of cell-polarization and protrusion dynamics. Our analysis links the data-driven shape analysis to the underlying causalities by identifying key parameters critical for migratory morphologies both normal and aberrant under genetic and pharmacological perturbations. The results underscore the importance of deciphering self-organizing states and their interplay when characterizing morphological phenotypes.
Topics: Animals; Cell Movement; Cell Polarity; Cell Shape; Cell Surface Extensions; Cells, Cultured; Cichlids; Computational Biology; Computer Simulation; Deep Learning; Dictyostelium; Fibroblasts; HL-60 Cells; Humans; Models, Biological
PubMed: 34383753
DOI: 10.1371/journal.pcbi.1009237 -
Secreted Cyclic Di-GMP Induces Stalk Cell Differentiation in the Eukaryote Dictyostelium discoideum.Journal of Bacteriology Jan 2016Cyclic di-GMP (c-di-GMP) is currently recognized as the most widely used intracellular signal molecule in prokaryotes, but roles in eukaryotes were only recently... (Review)
Review
Cyclic di-GMP (c-di-GMP) is currently recognized as the most widely used intracellular signal molecule in prokaryotes, but roles in eukaryotes were only recently discovered. In the social amoeba Dictyostelium discoideum, c-di-GMP, produced by a prokaryote-type diguanylate cyclase, induces the differentiation of stalk cells, thereby enabling the formation of spore-bearing fruiting bodies. In this review, we summarize the currently known mechanisms that control the major life cycle transitions of Dictyostelium and focus particularly on the role of c-di-GMP in stalk formation. Stalk cell differentiation has characteristics of autophagic cell death, a process that also occurs in higher eukaryotes. We discuss the respective roles of c-di-GMP and of another signal molecule, differentiation-inducing factor 1, in autophagic cell death in vitro and in stalk formation in vivo.
Topics: Cyclic GMP; Dictyostelium; Signal Transduction; Spores, Protozoan
PubMed: 26013485
DOI: 10.1128/JB.00321-15 -
FEBS Open Bio Jun 2020Copines are a family of cytosolic proteins that associate with membranes in a calcium-dependent manner and are found in many eukaryotic organisms....
Copines are a family of cytosolic proteins that associate with membranes in a calcium-dependent manner and are found in many eukaryotic organisms. Dictyostelium discoideum has six copine genes (cpnA-cpnF), and cells lacking cpnA(cpnA ) have defects in cytokinesis, chemotaxis, adhesion, and development. CpnA has also been shown to associate with the plasma membrane, contractile vacuoles (CV), and organelles of the endolysosomal pathway. Here, we use cpnA cells to investigate the role of CpnA in CV function and endocytosis. When placed in water, cpnA cells made abnormally large CVs that took longer to expel. Visualization of CVs with the marker protein GFP-dajumin indicated that cpnA cells had fewer CVs that sometimes refilled before complete emptying. In endocytosis assays, cpnA cells took up small fluorescent beads by macropinocytosis at rates similar to parental cells. However, cpnA cells reached a plateau sooner than parental cells and had less fluorescence at later time points. p80 antibody labeling of postlysosomes (PL) indicated that there were fewer and smaller PLs in cpnA cells. In dextran pulse-chase experiments, the number of PLs peaked earlier in cpnA cells, and the PLs did not become as large and disappeared sooner as compared to parental cells. PLs in cpnA cells were also shown to have more actin coats, suggesting CpnA may play a role in actin filament disassembly on PL membranes. Overall, these results indicate that CpnA is involved in the regulation of CV size and expulsion, and the maturation, size, and exocytosis of PLs.
Topics: Carrier Proteins; Cell Line; Cell Membrane; Chemotaxis; Dictyostelium; Exocytosis; Gene Knockout Techniques; Genes, Reporter; Green Fluorescent Proteins; Intravital Microscopy; Microscopy, Fluorescence; Protozoan Proteins; Time-Lapse Imaging; Vacuoles
PubMed: 32351039
DOI: 10.1002/2211-5463.12874