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Cells & Development Dec 2021Macropinocytosis is a form of endocytosis performed by ruffles and cups of the plasma membrane. These close to entrap droplets of medium into micron-sized vesicles,... (Review)
Review
Macropinocytosis is a form of endocytosis performed by ruffles and cups of the plasma membrane. These close to entrap droplets of medium into micron-sized vesicles, which are trafficked through the endocytic system, their contents digested and useful products absorbed. Macropinocytosis is constitutive in certain immune cells and stimulated in many other cells by growth factors. It occurs across the animal kingdom and in amoebae, implying a deep evolutionary history. Its scientific history goes back 100 years, but increasingly work is focused on its medical importance in the immune system, cancer cell feeding, and as a backdoor into cells for viruses and drugs. Macropinocytosis is driven by the actin cytoskeleton whose dynamics can be appreciated with lattice light sheet microscopy: this reveals a surprising variety of routes for forming macropinosomes. In Dictyostelium amoebae, macropinocytic cups are organized around domains of PIP3 and active Ras and Rac in the plasma membrane. These attract activators of the Arp2/3 complex to their periphery, creating rings of actin polymerization that shape the cups. The size of PIP3 domains is controlled by RasGAPs, such as NF1, and the lipid phosphatase, PTEN. It is likely that domain dynamics determine the shape, evolution and closing of macropinocytic structures.
Topics: Actin Cytoskeleton; Amoeba; Animals; Biology; Dictyostelium; Endocytosis; Pinocytosis
PubMed: 34175511
DOI: 10.1016/j.cdev.2021.203713 -
Journal of Biosciences 2022is a species of free-living soil amoeba that feeds on bacteria that grow on decaying vegetation. Though the present account deals with , I use the more colloquial...
is a species of free-living soil amoeba that feeds on bacteria that grow on decaying vegetation. Though the present account deals with , I use the more colloquial 'dictyostelium' in this article. In 1989, as a new PI, I began to study the response of D. discoideum amoebae to pisatin. Pisatin is the major phytoalexin of the pea plant (). Phytoalexins are antifungal compounds made by plants in response to infection and injury. No other group has studied any dictyostelium vis-a`-vis any phytoalexin. Evidence for saying so comes from PubMed: four papers show up with the keywords 'dictyostelium', and 'phytoalexin', all from my lab. Why did we 'plough this lonely furrow' and what did we uncover?
Topics: Dictyostelium; Pisum sativum; Antifungal Agents; Bacteria
PubMed: 36510437
DOI: No ID Found -
The International Journal of... 2019In the last few decades, we have learned a considerable amount about how eukaryotic cells communicate with each other, and what it is the cells are telling each other.... (Review)
Review
In the last few decades, we have learned a considerable amount about how eukaryotic cells communicate with each other, and what it is the cells are telling each other. The simplicity of Dictyostelium discoideum, and the wide variety of available tools to study this organism, makes it the equivalent of a hydrogen atom for cell and developmental biology. Studies using Dictyostelium have pioneered a good deal of our understanding of eukaryotic cell communication. In this review, we will present a brief overview of how Dictyostelium cells use extracellular signals to attract each other, repel each other, sense their local cell density, sense whether the nearby cells are starving or stressed, count themselves to organize the formation of structures containing a regulated number of cells, sense the volume they are in, and organize their multicellular development. Although we are probably just beginning to learn what the cells are telling each other, the elucidation of Dictyostelium extracellular signals has already led to the development of possible therapeutics for human diseases.
Topics: Adenine; Adenosine Triphosphate; Ammonia; Cell Communication; Chemotactic Factors; Culture Media, Conditioned; Cyclic AMP; Dictyostelium; Morphogenesis; Polyketides; Polyphosphates
PubMed: 31840778
DOI: 10.1387/ijdb.190259rg -
Current Opinion in Structural Biology Jun 2019O-Glycosylation is an increasingly recognized modification of intracellular proteins in all kingdoms of life, and its occurrence in protists has been investigated to... (Review)
Review
O-Glycosylation is an increasingly recognized modification of intracellular proteins in all kingdoms of life, and its occurrence in protists has been investigated to understand its evolution and its roles in the virulence of unicellular pathogens. We focus here on two kinds of glycoregulation found in unicellular eukaryotes: one is a simple O-fucose modification of dozens if not hundreds of Ser/Thr-rich proteins, and the other a complex pentasaccharide devoted to a single protein associated with oxygen sensing and the assembly of polyubiquitin chains. These modifications are not required for life but contingently modulate biological processes in the social amoeba Dictyostelium and the human pathogen Toxoplasma gondii, and likely occur in diverse unicellular protists. O-Glycosylation that is co-localized in the cytoplasm allows for glycoregulation over the entire life of the protein, contrary to the secretory pathway where glycosylation usually occurs before its delivery to its site of function. Here, we interpret cellular roles of nucleocytoplasmic glycans in terms of current evidence for their effects on the conformation and dynamics of protist proteins, to serve as a guide for future studies to examine their broader significance.
Topics: Cell Nucleus; Cytoplasm; Dictyostelium; Glycoproteins; Glycosylation; Toxoplasma
PubMed: 31128470
DOI: 10.1016/j.sbi.2019.03.031 -
Microbiology (Reading, England) Feb 2020
Topics: Dictyostelium; Gastrointestinal Microbiome; Humans; Metabolic Networks and Pathways; Microbiology; Pseudomonas; Signal Transduction
PubMed: 32122459
DOI: 10.1099/mic.0.000901 -
The International Journal of... 2019Sex in Dictyostelia involves a remarkable form of cannibalism in which zygotes attract large numbers of surrounding amoebae and then ingest them. Before they are... (Review)
Review
Sex in Dictyostelia involves a remarkable form of cannibalism in which zygotes attract large numbers of surrounding amoebae and then ingest them. Before they are consumed, the attracted amoebae help the zygote by synthesising an outer wall around the aggregate that traps them inside and helps to protect the mature developed zygotic structure, the macrocyst. Competition between cells vying to contribute genetically to zygotes and through to the next generation seems likely to have promoted the evolution of several unusual features of dictyostelid sex: individual species often have more than two mating types, increasing haploid cells' chances of matching with a compatible partner, and fusion of many gametes to form transient syncytia allows cytoplasmic mixing and lateral transmission of mitochondrial genomes. This review will summarise recent advances in our understanding of mating-type determination, gamete fusion, and inheritance in Dictyostelium, and highlight the key gaps in our understanding of this fascinating set of phenomena.
Topics: Cell Communication; Cell Nucleus; Cytoplasm; Dictyostelium; Genome; Germ Cells; Haploidy; Meiosis; Mitochondria; Reproduction
PubMed: 31840782
DOI: 10.1387/ijdb.190183gb -
The International Journal of... 2019The well-orchestrated multicellular life cycle of Dictyostelium discoideum has fascinated biologists for over a century. Self-organisation of its amoebas into... (Review)
Review
The well-orchestrated multicellular life cycle of Dictyostelium discoideum has fascinated biologists for over a century. Self-organisation of its amoebas into aggregates, migrating slugs and fruiting structures by pulsatile cAMP signalling and their ability to follow separate differentiation pathways in well-regulated proportions continue to be topics under investigation. A striking aspect of D. discoideum development is the recurrent use of cAMP as chemoattractant, differentiation inducing signal and second messenger for other signals that control the developmental programme. D. discoideum is one of >150 species of Dictyostelia and aggregative life styles similar to those of Dictyostelia evolved many times in eukaryotes. Here we review experimental studies investigating how phenotypic complexity and cAMP signalling co-evolved in Dictyostelia. In addition, we summarize comparative genomic studies of multicellular Dictyostelia and unicellular Amoebozoa aimed to identify evolutionary conservation and change in all genes known to be essential for D. discoideum development.
Topics: Biological Evolution; Cell Differentiation; Cyclic AMP; Dictyostelium; Gene Expression Regulation; Genome; Genomics; Phenotype; Phylogeny; Protein Domains; Signal Transduction
PubMed: 31840775
DOI: 10.1387/ijdb.190108ps -
Microbial Biotechnology Jan 2021Dictyostelium discoideum is one of eight non-mammalian model organisms recognized by the National Institute of Health for the study of human pathology. The use of this... (Review)
Review
Dictyostelium discoideum is one of eight non-mammalian model organisms recognized by the National Institute of Health for the study of human pathology. The use of this slime mould is possible owing to similarities in cell structure, behaviour and intracellular signalling with mammalian cells. Its haploid set of chromosomes completely sequenced amenable to genetic manipulation, its unique and short life cycle with unicellular and multicellular stages, and phenotypic richness encoding many human orthologues, make Dictyostelium a representative and simple model organism to unveil cellular processes in human disease. Dictyostelium studies within the biomedical field have provided fundamental knowledge in the areas of bacterial infection, immune cell chemotaxis, autophagy/phagocytosis and mitochondrial and neurological disorders. Consequently, Dictyostelium has been used to the development of related pharmacological treatments. Herein, we review the utilization of Dictyostelium as a model organism in biomedicine.
Topics: Animals; Dictyostelium; Humans; Signal Transduction
PubMed: 33124755
DOI: 10.1111/1751-7915.13692 -
The FEBS Journal Dec 2014Macro-autophagy (hereafter referred to as autophagy) delivers cytoplasmic material to the lysosome for degradation, and has been implicated in many cellular processes,... (Review)
Review
Macro-autophagy (hereafter referred to as autophagy) delivers cytoplasmic material to the lysosome for degradation, and has been implicated in many cellular processes, including stress, infection, survival and death. Although the regulation and role of autophagy in stress, infection and survival is apparent, its involvement during cell death remains relatively unclear. In this review, we highlight what is known about the role that autophagy can play during physiological cell death, and discuss the implications of better understanding cellular destruction that involves autophagy.
Topics: Animals; Arabidopsis; Autophagy; Cell Death; Dictyostelium; Drosophila melanogaster; Vertebrates
PubMed: 25323556
DOI: 10.1111/febs.13114 -
Current Biology : CB Jun 2019Cooperation has been essential to the evolution of biological complexity, but many societies struggle to overcome internal conflicts and divisions. Dictyostelium... (Review)
Review
Cooperation has been essential to the evolution of biological complexity, but many societies struggle to overcome internal conflicts and divisions. Dictyostelium discoideum, or the social amoeba, has been a useful model system for exploring these conflicts and how they can be resolved. When starved, these cells communicate, gather into groups, and build themselves into a multicellular fruiting body. Some cells altruistically die to form the rigid stalk, while the remainder sit atop the stalk, become spores, and disperse. Evolutionary theory predicts that conflict will arise over which cells die to form the stalk and which cells become spores and survive. The power of the social amoeba lies in the ability to explore how cooperation and conflict work across multiple levels, ranging from proximate mechanisms (how does it work?) to ultimate evolutionary answers (why does it work?). Recent studies point to solutions to the problem of ensuring fairness, such as the ability to suppress selfishness and to recognize and avoid unrelated individuals. This work confirms a central role for kin selection, but also suggests new explanations for how social amoebae might enforce cooperation. New approaches based on genomics are also enabling researchers to decipher for the first time the evolutionary history of cooperation and conflict and to determine its role in shaping the biology of multicellular organisms.
Topics: Biological Evolution; Dictyostelium; Microbial Interactions
PubMed: 31163162
DOI: 10.1016/j.cub.2019.04.022