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Cells Nov 2021The social amoeba provides an excellent model for research across a broad range of disciplines within biology. The organism diverged from the plant, yeast, fungi and... (Review)
Review
The social amoeba provides an excellent model for research across a broad range of disciplines within biology. The organism diverged from the plant, yeast, fungi and animal kingdoms around 1 billion years ago but retains common aspects found in these kingdoms. has a low level of genetic complexity and provides a range of molecular, cellular, biochemical and developmental biology experimental techniques, enabling multidisciplinary studies to be carried out in a wide range of areas, leading to research breakthroughs. Numerous laboratories within the United Kingdom employ as their core research model. This review introduces and then highlights research from several leading British research laboratories, covering their distinct areas of research, the benefits of using the model, and the breakthroughs that have arisen due to the use of as a tractable model system.
Topics: Animals; Biology; Dictyostelium; Drug Discovery; Models, Biological; Protein Processing, Post-Translational; Research; United Kingdom
PubMed: 34831258
DOI: 10.3390/cells10113036 -
Cells Feb 2019The nucleoli of have a comparatively unique, non-canonical, localization adjacent to the inner nuclear membrane. The verified nucleolar proteins of this eukaryotic... (Review)
Review
The nucleoli of have a comparatively unique, non-canonical, localization adjacent to the inner nuclear membrane. The verified nucleolar proteins of this eukaryotic microbe are detailed while other potential proteins are introduced. Heat shock protein 32 (Hsp32), eukaryotic translation initiation factor 6 (eIF6), and tumour necrosis factor receptor-associated protein 1 (TRAP1) are essential for cell survival. NumA1, a breast cancer type 1 susceptibility protein-C Terminus domain-containing protein linked to cell cycle, functions in the regulation of nuclear number. The cell cycle checkpoint kinase 2 homologue forkhead-associated kinase A (FhkA) and BRG1-associated factor 60a homologue Snf12 are also discussed. While nucleoli appear homogeneous ultrastructurally, evidence for nucleolar subcompartments exists. Nucleolar localization sequences (NoLS) have been defined that target proteins to either the general nucleolar area or to a specific intranucleolar domain. Protein translocations during mitosis are protein-specific and support the multiple functions of the nucleolus. To enrich the picture, binding partners of NumA1, the most well-characterized nucleolar protein, are examined: nucleolar Ca-binding protein 4a (CBP4a), nuclear puromycin-sensitive aminopeptidase A (PsaA) and Snf12. The role of as a model for understanding the contribution of nucleolar proteins to various diseases and cellular stress is discussed throughout the review.
Topics: Amino Acid Sequence; Cell Nucleolus; Dictyostelium; Nuclear Proteins; Prions; Protein Binding; Protein Transport
PubMed: 30781559
DOI: 10.3390/cells8020167 -
Cells Mar 2019Cell-derived extracellular vesicles (EVs) are newly uncovered messengers for intercellular communication. They are released by almost all cell types in the three... (Review)
Review
Cell-derived extracellular vesicles (EVs) are newly uncovered messengers for intercellular communication. They are released by almost all cell types in the three kingdoms, Archeabacteria, Bacteria and Eukaryotes. They are known to mediate important biological functions and to be increasingly involved in cell physiology and in many human diseases, especially in oncology. The aim of this review is to recapitulate the current knowledge about EVs and to summarize our pioneering work about EVs. However, many challenges remain unsolved in the EV research field, before any EV application for theranostics (diagnosis, prognosis, and therapy) of human cancers, can be efficiently implemented in the clinics. might be an outstanding eukaryotic cell model for deciphering the utmost challenging problem of EV heterogeneity, and for unraveling the still mostly unknown mechanisms of their specific functions as mediators of intercellular communication.
Topics: Animals; Dictyostelium; Disease; Drug Delivery Systems; Extracellular Vesicles; Health; Humans; Models, Biological
PubMed: 30857191
DOI: 10.3390/cells8030225 -
Cells Feb 2019Nuclear lamins are nucleus-specific intermediate filaments (IF) found at the inner nuclear membrane (INM) of the nuclear envelope (NE). Together with nuclear envelope...
Nuclear lamins are nucleus-specific intermediate filaments (IF) found at the inner nuclear membrane (INM) of the nuclear envelope (NE). Together with nuclear envelope transmembrane proteins, they form the nuclear lamina and are crucial for gene regulation and mechanical robustness of the nucleus and the whole cell. Recently, we characterized NE81 as an evolutionarily conserved lamin-like protein, both on the sequence and functional level. Here, we show on the structural level that the NE81 is also capable of assembling into filaments, just as metazoan lamin filament assemblies. Using field-emission scanning electron microscopy, we show that NE81 expressed in oocytes forms filamentous structures with an overall appearance highly reminiscent of lamin B2. The in vitro assembly properties of recombinant His-tagged NE81 purified from extracts are very similar to those of metazoan lamins. Super-resolution stimulated emission depletion (STED) and expansion microscopy (ExM), as well as transmission electron microscopy of negatively stained purified NE81, demonstrated its capability of forming filamentous structures under low-ionic-strength conditions. These results recommend as a non-mammalian model organism with a well-characterized nuclear envelope involving all relevant protein components known in animal cells.
Topics: Animals; Cell Membrane Permeability; Dictyostelium; Nuclear Envelope; Oocytes; Protozoan Proteins; Xenopus
PubMed: 30781468
DOI: 10.3390/cells8020162 -
Journal of Cell Science Jan 2019Macropinocytosis is an actin-driven process of large-scale and non-specific fluid uptake used for feeding by some cancer cells and the macropinocytosis model organism...
Macropinocytosis is an actin-driven process of large-scale and non-specific fluid uptake used for feeding by some cancer cells and the macropinocytosis model organism In , macropinocytic cups are organized by 'macropinocytic patches' in the plasma membrane. These contain activated Ras, Rac and phospholipid PIP3, and direct actin polymerization to their periphery. We show that a Akt (PkbA) and an SGK (PkbR1) protein kinase act downstream of PIP3 and, together, are nearly essential for fluid uptake. This pathway enables the formation of larger macropinocytic patches and macropinosomes, thereby dramatically increasing fluid uptake. Through phosphoproteomics, we identify a RhoGAP, GacG, as a PkbA and PkbR1 target, and show that it is required for efficient macropinocytosis and expansion of macropinocytic patches. The function of Akt and SGK in cell feeding through control of macropinosome size has implications for cancer cell biology.
Topics: Dictyostelium; Pinocytosis; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins c-akt; Protozoan Proteins
PubMed: 30617109
DOI: 10.1242/jcs.224998 -
Biological Reviews of the Cambridge... Apr 2020This review focusses on the functions of intracellular and extracellular calmodulin, its target proteins and their binding proteins during the asexual life cycle of... (Review)
Review
This review focusses on the functions of intracellular and extracellular calmodulin, its target proteins and their binding proteins during the asexual life cycle of Dictyostelium discoideum. Calmodulin is a primary regulatory protein of calcium signal transduction that functions throughout all stages. During growth, it mediates autophagy, the cell cycle, folic acid chemotaxis, phagocytosis, and other functions. During mitosis, specific calmodulin-binding proteins translocate to alternative locations. Translocation of at least one cell adhesion protein is calmodulin dependent. When starved, cells undergo calmodulin-dependent chemotaxis to cyclic AMP generating a multicellular pseudoplasmodium. Calmodulin-dependent signalling within the slug sets up a defined pattern and polarity that sets the stage for the final events of morphogenesis and cell differentiation. Transected slugs undergo calmodulin-dependent transdifferentiation to re-establish the disrupted pattern and polarity. Calmodulin function is critical for stalk cell differentiation but also functions in spore formation, events that begin in the pseudoplasmodium. The asexual life cycle restarts with the calmodulin-dependent germination of spores. Specific calmodulin-binding proteins as well as some of their binding partners have been linked to each of these events. The functions of extracellular calmodulin during growth and development are also discussed. This overview brings to the forefront the central role of calmodulin, working through its numerous binding proteins, as a primary downstream regulator of the critical calcium signalling pathways that have been well established in this model eukaryote. This is the first time the function of calmodulin and its target proteins have been documented through the complete life cycle of any eukaryote.
Topics: Calcium Signaling; Calmodulin; Cell Movement; Chemotaxis; Dictyostelium; Life Cycle Stages
PubMed: 31774219
DOI: 10.1111/brv.12573 -
Cells Feb 2020Individual gene analyses of microtubule-based motor proteins in have provided a rough draft of its machinery for cytoplasmic organization and division. This review... (Review)
Review
Individual gene analyses of microtubule-based motor proteins in have provided a rough draft of its machinery for cytoplasmic organization and division. This review collates their activities and looks forward to what is next. A comprehensive approach that considers the collective actions of motors, how they balance rates and directions, and how they integrate with the actin cytoskeleton will be necessary for a complete understanding of cellular dynamics.
Topics: Cell Movement; Dictyostelium; Microtubules; Protozoan Infections; Time Factors
PubMed: 32106406
DOI: 10.3390/cells9030528 -
ELife Aug 2021Using a self-generated hypoxic assay, we show that the amoeba displays a remarkable collective aerotactic behavior. When a cell colony is covered, cells quickly consume...
Using a self-generated hypoxic assay, we show that the amoeba displays a remarkable collective aerotactic behavior. When a cell colony is covered, cells quickly consume the available oxygen (O) and form a dense ring moving outwards at constant speed and density. To decipher this collective process, we combined two technological developments: porphyrin-based O -sensing films and microfluidic O gradient generators. We showed that cells exhibit aerotactic and aerokinetic response in a low range of O concentration indicative of a very efficient detection mechanism. Cell behaviors under self-generated or imposed O gradients were modeled using an in silico cellular Potts model built on experimental observations. This computational model was complemented with a parsimonious 'Go or Grow' partial differential equation (PDE) model. In both models, we found that the collective migration of a dense ring can be explained by the interplay between cell division and the modulation of aerotaxis.
Topics: Anaerobiosis; Chemotaxis; Dictyostelium; Oxygen
PubMed: 34415238
DOI: 10.7554/eLife.64731 -
BMC Biology Jul 2019Kinases mTORC1 and AMPK act as energy sensors, controlling nutrient responses and cellular growth. Changes in nutrient levels affect diverse transcriptional networks,...
BACKGROUND
Kinases mTORC1 and AMPK act as energy sensors, controlling nutrient responses and cellular growth. Changes in nutrient levels affect diverse transcriptional networks, making it challenging to identify downstream paths that regulate cellular growth or a switch to development via nutrient variation. The life cycle of Dictyostelium presents an excellent model to study the mTORC1 signaling function for growth and development. Dictyostelium grow as single cells in nutrient-rich media, but, upon nutrient withdrawal, growth ceases and cells enter a program for multi-cell development. While nearly half the genome shows gene expression changes upon nutrient removal, we hypothesized that not all of these genes are required for the switch to program development. Through manipulation of mTORC1 activity alone, without nutrient removal, we focused on a core network of genes that are required for switching between growth and development for regulation of cell fate decisions.
RESULTS
To identify developmentally essential genes, we sought ways to promote development in the absence of nutrient loss. We first examined the activities of mTORC1 and AMPK in Dictyostelium during phases of rapid growth and starvation-induced development and showed they exhibited reciprocal patterns of regulation under various conditions. Using these as initial readouts, we identified rich media conditions that promoted rapid cell growth but, upon mTORC1 inactivation by rapamycin, led to a growth/development switch. Examination of gene expression during cell fate switching showed that changes in expression of most starvation-regulated genes were not required for developmental induction. Approximately 1000 genes which become downregulated upon rapamycin treatment comprise a cellular growth network involving ribosome biogenesis, protein synthesis, and cell cycle processes. Conversely, the upregulation of ~ 500 genes by rapamycin treatment defines essential signaling pathways for developmental induction, and ~ 135 of their protein products intersect through the well-defined cAMP/PKA network. Many of the rapamycin-induced genes we found are currently unclassified, and mutation analyses of 5 such genes suggest a novel gene class essential for developmental regulation.
CONCLUSIONS
We show that manipulating activities of mTORC1/AMPK in the absence of nutrient withdrawal is sufficient for a growth-to-developmental fate switch in Dictyostelium, providing a means to identify transcriptional networks and signaling pathways essential for early development.
Topics: Adenylate Kinase; Cell Cycle; Dictyostelium; Mechanistic Target of Rapamycin Complex 1; Protozoan Proteins; Signal Transduction
PubMed: 31319820
DOI: 10.1186/s12915-019-0673-1 -
Frontiers in Cellular and Infection... 2018Microbes have interacted with eukaryotic cells for as long as they have been co-existing. While many of these interactions are beneficial for both the microbe as well as... (Review)
Review
Microbes have interacted with eukaryotic cells for as long as they have been co-existing. While many of these interactions are beneficial for both the microbe as well as the eukaryotic cell, several microbes have evolved into pathogenic species. For some of these pathogens, host cell invasion results in irreparable damage and thus host cell destruction, whereas others use the host to avoid immune detection and elimination. One of the latter pathogens is , arguably one of the most notorious pathogens on earth. In mammalian macrophages, manages to survive within infected macrophages by avoiding intracellular degradation in lysosomes using a number of different strategies. One of these is based on the recruitment and phagosomal retention of the host protein coronin 1, that is a member of the coronin protein family and a mammalian homolog of coronin A, a protein identified in . Besides mediating mycobacterial survival in macrophages, coronin 1 is also an important regulator of naïve T cell homeostasis. How, exactly, coronin 1 mediates its activity in immune cells remains unclear. While in lower eukaryotes coronins are involved in cytoskeletal regulation, the functions of the seven coronin members in mammals are less clear. coronins may have maintained multiple functions, whereas the mammalian coronins may have evolved from regulators of the cytoskeleton to modulators of signal transduction. In this minireview, we will discuss the different studies that have contributed to understand the molecular and cellular functions of coronin proteins in mammals and .
Topics: Animals; Dictyostelium; Humans; Mammals; Microfilament Proteins; Mycobacterium tuberculosis; Phagocytes; Tuberculosis
PubMed: 29623258
DOI: 10.3389/fcimb.2018.00077