1
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Erisis S, Hörning M. Self-organization of PIP3 waves is controlled by the topology and curvature of cell membranes. Biophys J 2024; 123:1058-1068. [PMID: 38515298 PMCID: PMC11079865 DOI: 10.1016/j.bpj.2024.03.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 03/13/2024] [Accepted: 03/18/2024] [Indexed: 03/23/2024] Open
Abstract
Phosphatidylinositol (3,4,5)-trisphosphate (PIP3) is a signaling lipid on the plasma membrane that plays a fundamental role in cell signaling with a strong impact on cell physiology and diseases. It is responsible for the protruding edge formation, cell polarization, macropinocytosis, and other membrane remodeling dynamics in cells. It has been shown that the membrane confinement and curvature affects the wave formation of PIP3 and F-actin. But, even in the absence of F-actin, a complex self-organization of the spatiotemporal PIP3 waves is observed. In recent findings, we have shown that these waves can be guided and pinned on strongly bended Dictyostelium membranes caused by molecular crowding and curvature-limited diffusion. Based on these experimental findings, we investigate the spatiotemporal PIP3 wave dynamics on realistic three-dimensional cell-like membranes to explore the effect of curvature-limited diffusion, as observed experimentally. We use an established stochastic reaction-diffusion model with enzymatic Michaelis-Menten-type reactions that mimics the dynamics of Dictyostelium cells. As these cells mimic the three-dimensional shape and size observed experimentally, we found that the PIP3 wave directionality can be explained by a Hopf-like and a reverse periodic-doubling bifurcation for uniform diffusion and curvature-limited diffusion properties. Finally, we compare the results with recent experimental findings and discuss the discrepancy between the biological and numerical results.
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Affiliation(s)
- Sema Erisis
- Institute of Biomaterials and Biomolecular Systems, University of Stuttgart, Stuttgart, Germany
| | - Marcel Hörning
- Institute of Biomaterials and Biomolecular Systems, University of Stuttgart, Stuttgart, Germany.
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2
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Jaiswal P, Meena NP, Chang FS, Liao XH, Kim L, Kimmel AR. An integrated, cross-regulation pathway model involving activating/adaptive and feed-forward/feed-back loops for directed oscillatory cAMP signal-relay/response during the development of Dictyostelium. Front Cell Dev Biol 2024; 11:1263316. [PMID: 38357530 PMCID: PMC10865387 DOI: 10.3389/fcell.2023.1263316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 12/19/2023] [Indexed: 02/16/2024] Open
Abstract
Self-organized and excitable signaling activities play important roles in a wide range of cellular functions in eukaryotic and prokaryotic cells. Cells require signaling networks to communicate amongst themselves, but also for response to environmental cues. Such signals involve complex spatial and temporal loops that may propagate as oscillations or waves. When Dictyostelium become starved for nutrients, cells within a localized space begin to secrete cAMP. Starved cells also become chemotactic to cAMP. cAMP signals propagate as outwardly moving waves that oscillate at ∼6 min intervals, which creates a focused territorial region for centralized cell aggregation. Proximal cells move inwardly toward the cAMP source and relay cAMP outwardly to recruit additional cells. To ensure directed inward movement and outward cAMP relay, cells go through adapted and de-adapted states for both cAMP synthesis/degradation and for directional cell movement. Although many immediate components that regulate cAMP signaling (including receptors, G proteins, an adenylyl cyclase, phosphodiesterases, and protein kinases) are known, others are only inferred. Here, using biochemical experiments coupled with gene inactivation studies, we model an integrated large, multi-component kinetic pathway involving activation, inactivation (adaptation), re-activation (re-sensitization), feed-forward, and feed-back controls to generate developmental cAMP oscillations.
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Affiliation(s)
- Pundrik Jaiswal
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, The National Institutes of Health, Bethesda, MD, United States
| | - Netra Pal Meena
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, The National Institutes of Health, Bethesda, MD, United States
| | - Fu-Sheng Chang
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, The National Institutes of Health, Bethesda, MD, United States
| | - Xin-Hua Liao
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, The National Institutes of Health, Bethesda, MD, United States
| | - Lou Kim
- Department of Biological Sciences, Florida International University, Miami, FL, United States
| | - Alan R. Kimmel
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, The National Institutes of Health, Bethesda, MD, United States
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3
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Wang Q, Wu H. Mathematical modeling of chemotaxis guided amoeboid cell swimming. Phys Biol 2021; 18. [PMID: 33853049 DOI: 10.1088/1478-3975/abf7d8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Accepted: 04/14/2021] [Indexed: 01/15/2023]
Abstract
Cells and microorganisms adopt various strategies to migrate in response to different environmental stimuli. To date, many modeling research has focused on the crawling-basedDictyostelium discoideum(Dd) cells migration induced by chemotaxis, yet recent experimental results reveal that even without adhesion or contact to a substrate, Dd cells can still swim to follow chemoattractant signals. In this paper, we develop a modeling framework to investigate the chemotaxis induced amoeboid cell swimming dynamics. A minimal swimming system consists of one deformable Dd amoeboid cell and a dilute suspension of bacteria, and the bacteria produce chemoattractant signals that attract the Dd cell. We use themathematical amoeba modelto generate Dd cell deformation and solve the resulting low Reynolds number flows, and use a moving mesh based finite volume method to solve the reaction-diffusion-convection equation. Using the computational model, we show that chemotaxis guides a swimming Dd cell to follow and catch bacteria, while on the other hand, bacterial rheotaxis may help the bacteria to escape from the predator Dd cell.
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Affiliation(s)
- Qixuan Wang
- Department of Mathematics, University of California, Riverside, CA, United States of America.,Interdisciplinary Center for Quantitative Modeling in Biology, University of California, Riverside, CA, United States of America
| | - Hao Wu
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA, United States of America
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4
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Belotti Y, McGloin D, Weijer CJ. Effects of spatial confinement on migratory properties of Dictyostelium discoideum cells. Commun Integr Biol 2021; 14:5-14. [PMID: 33552382 PMCID: PMC7849737 DOI: 10.1080/19420889.2021.1872917] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Migratory environments of various eukaryotic cells, such as amoeba, leukocytes and cancer cells, typically involve spatial confinement. Numerous studies have recently emerged, aimed to develop experimental platforms that better recapitulate the characteristics of the cellular microenvironment. Using microfluidic technologies, we show that increasing confinement of Dictyostelium discoideum cells into narrower micro-channels resulted in a significant change in the mode of migration and associated arrangement of the actomyosin cytoskeleton. We observed that cells tended to migrate at constant speed, the magnitude of which was dependent on the size of the channels, as was the locomotory strategy adopted by each cell. Two different migration modes were observed, pseudopod-based and bleb-based migration, with bleb based migration being more frequent with increasing confinement and leading to slower migration. Beside the migration mode, we found that the major determinants of cell speed are its protrusion rate, the amount of F-actin at its leading edge and the number of actin foci. Our results highlighted the impact of the microenvironments on cell behavior. Furthermore, we developed a novel quantitative movement analysis platform for mono-dimensional cell migration that allows for standardization and simplification of the experimental conditions and aids investigation of the complex and dynamic processes occurring at the single-cell level.
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Affiliation(s)
- Yuri Belotti
- School of Science and Engineering, University of Dundee, Dundee, Scotland, UK
| | - David McGloin
- School of Science and Engineering, University of Dundee, Dundee, Scotland, UK
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5
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Arias Del Angel JA, Nanjundiah V, Benítez M, Newman SA. Interplay of mesoscale physics and agent-like behaviors in the parallel evolution of aggregative multicellularity. EvoDevo 2020; 11:21. [PMID: 33062243 PMCID: PMC7549232 DOI: 10.1186/s13227-020-00165-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 09/08/2020] [Indexed: 12/12/2022] Open
Abstract
Myxobacteria and dictyostelids are prokaryotic and eukaryotic multicellular lineages, respectively, that after nutrient depletion aggregate and develop into structures called fruiting bodies. The developmental processes and resulting morphological outcomes resemble one another to a remarkable extent despite their independent origins, the evolutionary distance between them and the lack of traceable homology in molecular mechanisms. We hypothesize that the morphological parallelism between the two lineages arises as the consequence of the interplay within multicellular aggregates between generic processes, physical and physicochemical processes operating similarly in living and non-living matter at the mesoscale (~10-3-10-1 m) and agent-like behaviors, unique to living systems and characteristic of the constituent cells, considered as autonomous entities acting according to internal rules in a shared environment. Here, we analyze the contributions of generic and agent-like determinants in myxobacteria and dictyostelid development and their roles in the generation of their common traits. Consequent to aggregation, collective cell-cell contacts mediate the emergence of liquid-like properties, making nascent multicellular masses subject to novel patterning and morphogenetic processes. In both lineages, this leads to behaviors such as streaming, rippling, and rounding-up, as seen in non-living fluids. Later the aggregates solidify, leading them to exhibit additional generic properties and motifs. Computational models suggest that the morphological phenotypes of the multicellular masses deviate from the predictions of generic physics due to the contribution of agent-like behaviors of cells such as directed migration, quiescence, and oscillatory signal transduction mediated by responses to external cues. These employ signaling mechanisms that reflect the evolutionary histories of the respective organisms. We propose that the similar developmental trajectories of myxobacteria and dictyostelids are more due to shared generic physical processes in coordination with analogous agent-type behaviors than to convergent evolution under parallel selection regimes. Insights from the biology of these aggregative forms may enable a unified understanding of developmental evolution, including that of animals and plants.
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Affiliation(s)
- Juan A Arias Del Angel
- Laboratorio Nacional de Ciencias de La Sostenibilidad, Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico City, Mexico.,Centro de Ciencias de La Complejidad, Universidad Nacional Autónoma de México, Mexico City, Mexico.,Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY 10595 USA.,Programa de Doctorado en Ciencias Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | | | - Mariana Benítez
- Laboratorio Nacional de Ciencias de La Sostenibilidad, Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico City, Mexico.,Centro de Ciencias de La Complejidad, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Stuart A Newman
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY 10595 USA
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6
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Consalvo KM, Rijal R, Tang Y, Kirolos SA, Smith MR, Gomer RH. Extracellular signaling in Dictyostelium. THE INTERNATIONAL JOURNAL OF DEVELOPMENTAL BIOLOGY 2020; 63:395-405. [PMID: 31840778 DOI: 10.1387/ijdb.190259rg] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
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.
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Affiliation(s)
- Kristen M Consalvo
- Department of Biology, Texas A∧M University, College Station, Texas, USA
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7
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Niklas KJ, Newman SA. The many roads to and from multicellularity. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:3247-3253. [PMID: 31819969 PMCID: PMC7289717 DOI: 10.1093/jxb/erz547] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 12/07/2019] [Indexed: 05/02/2023]
Abstract
The multiple origins of multicellularity had far-reaching consequences ranging from the appearance of phenotypically complex life-forms to their effects on Earth's aquatic and terrestrial ecosystems. Yet, many important questions remain. For example, do all lineages and clades share an ancestral developmental predisposition for multicellularity emerging from genomic and biophysical motifs shared from a last common ancestor, or are the multiple origins of multicellularity truly independent evolutionary events? In this review, we highlight recent developments and pitfalls in understanding the evolution of multicellularity with an emphasis on plants (here defined broadly to include the polyphyletic algae), but also draw upon insights from animals and their holozoan relatives, fungi and amoebozoans. Based on our review, we conclude that the evolution of multicellular organisms requires three phases (origination by disparate cell-cell attachment modalities, followed by integration by lineage-specific physiological mechanisms, and autonomization by natural selection) that have been achieved differently in different lineages.
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Affiliation(s)
- Karl J Niklas
- Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
- Correspondence:
| | - Stuart A Newman
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, USA
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8
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Saunders CA, Parent CA. Emerging roles for the nucleus during neutrophil signal relay and NETosis. Curr Opin Cell Biol 2019; 62:135-143. [PMID: 31835148 DOI: 10.1016/j.ceb.2019.10.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 10/14/2019] [Accepted: 10/29/2019] [Indexed: 01/21/2023]
Abstract
The nucleus houses and protects genomic DNA, which is surrounded by the nuclear envelope. Owing to its size and stiffness, the nucleus is often a barrier to migration through confined spaces. Neutrophils are terminally differentiated, short-lived cells that migrate through tissues in response to injury and infections. The neutrophil nucleus is soft, multilobular, and exhibits altered levels of key nuclear envelope proteins. These alterations result in a multifunctional organelle that serves as a signaling hub during migration and NETosis, a process by which neutrophils release decondensed chromatin decorated with granular enzymes that entrap pathogens. In this review, we present emerging evidence suggesting that a unique, ambiguous cell-cycle state is critical for NETosis and migration. Finally, we discuss how the mechanisms underlying migration and NETosis are evolutionarily conserved.
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Affiliation(s)
| | - Carole A Parent
- Department of Pharmacology; Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
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9
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Newman SA. Inherent forms and the evolution of evolution. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2019; 332:331-338. [PMID: 31380606 DOI: 10.1002/jez.b.22895] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 07/07/2019] [Accepted: 07/09/2019] [Indexed: 12/24/2022]
Abstract
John Bonner presented a provocative conjecture that the means by which organisms evolve has itself evolved. The elements of his postulated nonuniformitarianism in the essay under discussion-the emergence of sex, the enhanced selection pressures on larger multicellular forms-center on a presumed close mapping of genotypic to phenotypic change. A different view emerges from delving into earlier work of Bonner's in which he proposed the concept of "neutral phenotypes" and "neutral morphologies" allied to D'Arcy Thompson's analysis of physical determinants of form and studied the conditional elicitation of intrinsic organizational properties of cell aggregates in social amoebae. By comparing the shared and disparate mechanistic bases of morphogenesis and developmental outcomes in the embryos of metazoans (animals), closely related nonmetazoan holozoans, more distantly related dictyostelids, and very distantly related volvocine algae, I conclude, in agreement with Bonner's earlier proposals, that understanding the evolution of multicellular evolution requires knowledge of the inherent forms of diversifying lineages, and that the relevant causative factors extend beyond genes and adaptation to the physics of materials.
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Affiliation(s)
- Stuart A Newman
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York
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10
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Hehmeyer J. Two potential evolutionary origins of the fruiting bodies of the dictyostelid slime moulds. Biol Rev Camb Philos Soc 2019; 94:1591-1604. [PMID: 30989827 DOI: 10.1111/brv.12516] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 03/29/2019] [Accepted: 04/01/2019] [Indexed: 11/29/2022]
Abstract
Dictyostelium discoideum and the other dictyostelid slime moulds ('social amoebae') are popular model organisms best known for their demonstration of sorocarpic development. In this process, many cells aggregate to form a multicellular unit that ultimately becomes a fruiting body bearing asexual spores. Several other unrelated microorganisms undergo comparable processes, and in some it is evident that their multicellular development evolved from the differentiation process of encystation. While it has been argued that the dictyostelid fruiting body had similar origins, it has also been proposed that dictyostelid sorocarpy evolved from the unicellular fruiting process found in other amoebozoan slime moulds. This paper reviews the developmental biology of the dictyostelids and other relevant organisms and reassesses the two hypotheses on the evolutionary origins of dictyostelid development. Recent advances in phylogeny, genetics, and genomics and transcriptomics indicate that further research is necessary to determine whether or not the fruiting bodies of the dictyostelids and their closest relatives, the myxomycetes and protosporangids, are homologous.
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11
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Krishnan J, Floros I. Adaptive information processing of network modules to dynamic and spatial stimuli. BMC SYSTEMS BIOLOGY 2019; 13:32. [PMID: 30866946 PMCID: PMC6417070 DOI: 10.1186/s12918-019-0703-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 02/08/2019] [Indexed: 12/15/2022]
Abstract
BACKGROUND Adaptation and homeostasis are basic features of information processing in cells and seen in a broad range of contexts. Much of the current understanding of adaptation in network modules/motifs is based on their response to simple stimuli. Recently, there have also been studies of adaptation in dynamic stimuli. However a broader synthesis of how different circuits of adaptation function, and which circuits enable a broader adaptive behaviour in classes of more complex and spatial stimuli is largely missing. RESULTS We study the response of a variety of adaptive circuits to time-varying stimuli such as ramps, periodic stimuli and static and dynamic spatial stimuli. We find that a variety of responses can be seen in ramp stimuli, making this a basis for discriminating between even similar circuits. We also find that a number of circuits adapt exactly to ramp stimuli, and dissect these circuits to pinpoint what characteristics (architecture, feedback, biochemical aspects, information processing ingredients) allow for this. These circuits include incoherent feedforward motifs, inflow-outflow motifs and transcritical circuits. We find that changes in location in such circuits where a signal acts can result in non-adaptive behaviour in ramps, even though the location was associated with exact adaptation in step stimuli. We also demonstrate that certain augmentations of basic inflow-outflow motifs can alter the behaviour of the circuit from exact adaptation to non-adaptive behaviour. When subject to periodic stimuli, some circuits (inflow-outflow motifs and transcritical circuits) are able to maintain an average output independent of the characteristics of the input. We build on this to examine the response of adaptive circuits to static and dynamic spatial stimuli. We demonstrate how certain circuits can exhibit a graded response in spatial static stimuli with an exact maintenance of the spatial mean-value. Distinct features which emerge from the consideration of dynamic spatial stimuli are also discussed. Finally, we also build on these results to show how different circuits which show any combination of presence or absence of exact adaptation in ramps, exact mainenance of time average output in periodic stimuli and exact maintenance of spatial average of output in static spatial stimuli may be realized. CONCLUSIONS By studying a range of network circuits/motifs on one hand and a range of stimuli on the other, we isolate characteristics of these circuits (structural) which enable different degrees of exact adaptive and homeostatic behaviour in such stimuli, how they may be combined, and also identify cases associated with non-homeostatic behaviour. We also reveal constraints associated with locations where signals may act to enable homeostatic behaviour and constraints associated with augmentations of circuits. This consideration of multiple experimentally/naturally relevant stimuli along with circuits of adaptation of relevance in natural and engineered biology, provides a platform for deepening our understanding of adaptive and homeostatic behaviour in natural systems, bridging the gap between models of adaptation and experiments and in engineering homeostatic synthetic circuits.
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Affiliation(s)
- J Krishnan
- Department of Chemical Engineering, Centre for Process Systems Engineering, Imperial College London, South Kensington, London, SW7 2AZ, UK.
| | - Ioannis Floros
- Department of Chemical Engineering, Centre for Process Systems Engineering, Imperial College London, South Kensington, London, SW7 2AZ, UK.,National Centre of Scientific Research "Demokritos", Athens, Greece
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12
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Wen X, Xu X, Sun W, Chen K, Pan M, Wang JM, Bolland SM, Jin T. G-protein-coupled formyl peptide receptors play a dual role in neutrophil chemotaxis and bacterial phagocytosis. Mol Biol Cell 2018; 30:346-356. [PMID: 30540534 PMCID: PMC6589574 DOI: 10.1091/mbc.e18-06-0358] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
A dogma of innate immunity is that neutrophils use G-protein–coupled receptors (GPCRs) for chemoattractant to chase bacteria through chemotaxis and then use phagocytic receptors coupled with tyrosine kinases to destroy opsonized bacteria via phagocytosis. Our current work showed that G-protein–coupled formyl peptide receptors (FPRs) directly mediate neutrophil phagocytosis. Mouse neutrophils lacking formyl peptide receptors (Fpr1/2–/–) are defective in the phagocytosis of Escherichia coli and the chemoattractant N-formyl-Met-Leu-Phe (fMLP)-coated beads. fMLP immobilized onto the surface of a bead interacts with FPRs, which trigger a Ca2+ response and induce actin polymerization to form a phagocytic cup for engulfment of the bead. This chemoattractant GPCR/Gi signaling works independently of phagocytic receptor/tyrosine kinase signaling to promote phagocytosis. Thus, in addition to phagocytic receptor-mediated phagocytosis, neutrophils also utilize the chemoattractant GPCR/Gi signaling to mediate phagocytosis to fight against invading bacteria.
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Affiliation(s)
- Xi Wen
- Chemotaxis Signal Section, National Institutes of Health, Bethesda, MD 20852
| | - Xuehua Xu
- Chemotaxis Signal Section, National Institutes of Health, Bethesda, MD 20852
| | - Wenxiang Sun
- Autoimmunity and Functional Genomics Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20852
| | - Keqiang Chen
- Cancer and Inflammation Program, Center for Cancer Research, National Cancer Research Institute at Frederick, Frederick, MD 21702-1201
| | - Miao Pan
- Chemotaxis Signal Section, National Institutes of Health, Bethesda, MD 20852
| | - Ji Ming Wang
- Cancer and Inflammation Program, Center for Cancer Research, National Cancer Research Institute at Frederick, Frederick, MD 21702-1201
| | - Silvia M Bolland
- Autoimmunity and Functional Genomics Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20852
| | - Tian Jin
- Chemotaxis Signal Section, National Institutes of Health, Bethesda, MD 20852
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13
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Thomas MA, Kleist AB, Volkman BF. Decoding the chemotactic signal. J Leukoc Biol 2018; 104:359-374. [PMID: 29873835 PMCID: PMC6099250 DOI: 10.1002/jlb.1mr0218-044] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 02/25/2018] [Indexed: 12/20/2022] Open
Abstract
From an individual bacterium to the cells that compose the human immune system, cellular chemotaxis plays a fundamental role in allowing cells to navigate, interpret, and respond to their environments. While many features of cellular chemotaxis are shared among systems as diverse as bacteria and human immune cells, the machinery that guides the migration of these model organisms varies widely. In this article, we review current literature on the diversity of chemoattractant ligands, the cell surface receptors that detect and process chemotactic gradients, and the link between signal recognition and the regulation of cellular machinery that allow for efficient directed cellular movement. These facets of cellular chemotaxis are compared among E. coli, Dictyostelium discoideum, and mammalian neutrophils to derive organizational principles by which diverse cell systems sense and respond to chemotactic gradients to initiate cellular migration.
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Affiliation(s)
- Monica A. Thomas
- Department of BiochemistryMedical College of WisconsinMilwaukeeWisconsinUSA
| | - Andrew B. Kleist
- Department of BiochemistryMedical College of WisconsinMilwaukeeWisconsinUSA
| | - Brian F. Volkman
- Department of BiochemistryMedical College of WisconsinMilwaukeeWisconsinUSA
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14
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Wang W, Chen S, Das S, Losert W, Parent CA. Adenylyl cyclase A mRNA localized at the back of cells is actively translated in live chemotaxing Dictyostelium. J Cell Sci 2018; 131:jcs.216176. [PMID: 29618632 DOI: 10.1242/jcs.216176] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 03/26/2018] [Indexed: 11/20/2022] Open
Abstract
Dictyostelium discoideum cells transport adenylyl cyclase A (ACA)-containing vesicles to the back of polarized cells to relay exogenous cAMP signals during chemotaxis. Fluorescence in situ hybridization (FISH) experiments showed that ACA mRNA is also asymmetrically distributed at the back of polarized cells. By using the MS2 bacteriophage system, we now visualize the distribution of ACA mRNA in live chemotaxing cells. We found that the ACA mRNA localization is not dependent on the translation of the protein product and requires multiple cis-acting elements within the ACA-coding sequence. We show that ACA mRNA is associated with actively translating ribosomes and is transported along microtubules towards the back of cells. By monitoring the recovery of ACA-YFP after photobleaching, we observed that local translation of ACA-YFP occurs at the back of cells. These data represent a novel functional role for localized translation in the relay of chemotactic signals during chemotaxis.
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Affiliation(s)
- Weiye Wang
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892, USA
| | - Song Chen
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892, USA.,Department of Pharmacology, Michigan Medicine, Ann Arbor, MI 48109, USA.,Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USA
| | - Satarupa Das
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892, USA.,Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USA
| | - Wolfgang Losert
- Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USA
| | - Carole A Parent
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892, USA .,Department of Pharmacology, Michigan Medicine, Ann Arbor, MI 48109, USA.,Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USA
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An Autocrine Proliferation Repressor Regulates Dictyostelium discoideum Proliferation and Chemorepulsion Using the G Protein-Coupled Receptor GrlH. mBio 2018; 9:mBio.02443-17. [PMID: 29440579 PMCID: PMC5821085 DOI: 10.1128/mbio.02443-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
In eukaryotic microbes, little is known about signals that inhibit the proliferation of the cells that secrete the signal, and little is known about signals (chemorepellents) that cause cells to move away from the source of the signal. Autocrine proliferation repressor protein A (AprA) is a protein secreted by the eukaryotic microbe Dictyostelium discoideum. AprA is a chemorepellent for and inhibits the proliferation of D. discoideum. We previously found that cells sense AprA using G proteins, suggesting the existence of a G protein-coupled AprA receptor. To identify the AprA receptor, we screened mutants lacking putative G protein-coupled receptors. We found that, compared to the wild-type strain, cells lacking putative receptor GrlH (grlH¯ cells) show rapid proliferation, do not have large numbers of cells moving away from the edges of colonies, are insensitive to AprA-induced proliferation inhibition and chemorepulsion, and have decreased AprA binding. Expression of GrlH in grlH¯ cells (grlH¯/grlHOE) rescues the phenotypes described above. These data indicate that AprA signaling may be mediated by GrlH in D. discoideum. Little is known about how eukaryotic cells can count themselves and thus regulate the size of a tissue or density of cells. In addition, little is known about how eukaryotic cells can sense a repellant signal and move away from the source of the repellant, for instance, to organize the movement of cells in a developing embryo or to move immune cells out of a tissue. In this study, we found that a eukaryotic microbe uses G protein-coupled receptors to mediate both cell density sensing and chemorepulsion.
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Aufderheide KJ, Janetopoulos C. Migration of Dictyostelium discoideum to the Chemoattractant Folic Acid. Methods Mol Biol 2017; 1407:25-39. [PMID: 27271892 DOI: 10.1007/978-1-4939-3480-5_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Dictyostelium discoideum can be grown axenically in a cultured media or in the presence of a natural food source, such as the bacterium Klebsiella aerogenes (KA). Here we describe the advantages and methods for growing D. discoideum on a bacterial lawn for several processes studied using this model system. When grown on a bacterial lawn, D. discoideum show positive chemotaxis towards folic acid (FA). While these vegetative cells are highly unpolarized, it has been shown that the signaling and cytoskeletal molecules regulating the directed migration of these cells are homologous to those seen in the motility of polarized cells in response to the chemoattractant cyclic adenosine monophosphate (cAMP). Growing D. discoideum on KA stimulates chemotactic responsiveness to FA. A major advantage of performing FA-mediated chemotaxis is that it does not require expression of the cAMP developmental program and therefore has the potential to identify mutants that are purely unresponsive to chemoattractant gradients. The cAMP-mediated chemotaxis can appear to fail when cells are developmentally delayed or do not up-regulate genes needed for cAMP-mediated migration. In addition to providing robust chemotaxis to FA, cells grown on bacterial lawns are highly resistant to light damage during fluorescence microscopy. This resistance to light damage could be exploited to better understand other biological processes such as phagocytosis or cytokinesis. The cell cycle is also shortened when cells are grown in the presence of KA, so the chances of seeing a mitotic event increases.
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Affiliation(s)
| | - Chris Janetopoulos
- Department of Biological Sciences, University of the Sciences, 600 S. 43rd St., Philadelphia, PA, 19104, USA.
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17
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Le Duc D, Schulz A, Lede V, Schulze A, Thor D, Brüser A, Schöneberg T. P2Y Receptors in Immune Response and Inflammation. Adv Immunol 2017; 136:85-121. [PMID: 28950952 DOI: 10.1016/bs.ai.2017.05.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Metabotropic pyrimidine and purine nucleotide receptors (P2Y receptors) are expressed in virtually all cells with implications in very diverse biological functions, including the well-established platelet aggregation (P2Y12), but also immune regulation and inflammation. The classical P2Y receptors bind nucleotides and are encoded by eight genes with limited sequence homology, while phylogenetically related receptors (e.g., P2Y12-like) recognize lipids and peptides, but also nucleotide derivatives. Growing lines of evidence suggest an important function of P2Y receptors in immune cell differentiation and maturation, migration, and cell apoptosis. Here, we give a perspective on the P2Y receptors' molecular structure and physiological importance in immune cells, as well as the related diseases and P2Y-targeting therapies. Extensive research is being undertaken to find modulators of P2Y receptors and uncover their physiological roles. We anticipate the medical applications of P2Y modulators and their immune relevance.
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Affiliation(s)
- Diana Le Duc
- Rudolf Schönheimer Institute of Biochemistry, Molecular Biochemistry, University of Leipzig, Leipzig, Germany
| | - Angela Schulz
- Rudolf Schönheimer Institute of Biochemistry, Molecular Biochemistry, University of Leipzig, Leipzig, Germany
| | - Vera Lede
- Rudolf Schönheimer Institute of Biochemistry, Molecular Biochemistry, University of Leipzig, Leipzig, Germany
| | - Annelie Schulze
- Rudolf Schönheimer Institute of Biochemistry, Molecular Biochemistry, University of Leipzig, Leipzig, Germany
| | - Doreen Thor
- Rudolf Schönheimer Institute of Biochemistry, Molecular Biochemistry, University of Leipzig, Leipzig, Germany
| | - Antje Brüser
- Rudolf Schönheimer Institute of Biochemistry, Molecular Biochemistry, University of Leipzig, Leipzig, Germany
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18
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Das S, Parker JM, Guven C, Wang W, Kriebel PW, Losert W, Larson DR, Parent CA. Adenylyl cyclase mRNA localizes to the posterior of polarized DICTYOSTELIUM cells during chemotaxis. BMC Cell Biol 2017; 18:23. [PMID: 28545392 PMCID: PMC5445419 DOI: 10.1186/s12860-017-0139-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 05/09/2017] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND In Dictyostelium discoideum, vesicular transport of the adenylyl cyclase A (ACA) to the posterior of polarized cells is essential to relay exogenous 3',5'-cyclic adenosine monophosphate (cAMP) signals during chemotaxis and for the collective migration of cells in head-to-tail arrangements called streams. RESULTS Using fluorescence in situ hybridization (FISH), we discovered that the ACA mRNA is asymmetrically distributed at the posterior of polarized cells. Using both standard estimators and Monte Carlo simulation methods, we found that the ACA mRNA enrichment depends on the position of the cell within a stream, with the posterior localization of ACA mRNA being strongest for cells at the end of a stream. By monitoring the recovery of ACA-YFP after cycloheximide (CHX) treatment, we observed that ACA mRNA and newly synthesized ACA-YFP first emerge as fluorescent punctae that later accumulate to the posterior of cells. We also found that the ACA mRNA localization requires 3' ACA cis-acting elements. CONCLUSIONS Together, our findings suggest that the asymmetric distribution of ACA mRNA allows the local translation and accumulation of ACA protein at the posterior of cells. These data represent a novel functional role for localized translation in the relay of chemotactic signal during chemotaxis.
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Affiliation(s)
- Satarupa Das
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, 37 Convent Drive, Bldg.37/Rm2066, NCI, NIH, Bethesda, MD, 20892-4256, USA.,Institute for Physical Science and Technology, Department of Physics, University of Maryland, College Park, MD, 20742, USA
| | - Joshua M Parker
- Institute for Physical Science and Technology, Department of Physics, University of Maryland, College Park, MD, 20742, USA
| | - Can Guven
- Institute for Physical Science and Technology, Department of Physics, University of Maryland, College Park, MD, 20742, USA
| | - Weiye Wang
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, 37 Convent Drive, Bldg.37/Rm2066, NCI, NIH, Bethesda, MD, 20892-4256, USA
| | - Paul W Kriebel
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, 37 Convent Drive, Bldg.37/Rm2066, NCI, NIH, Bethesda, MD, 20892-4256, USA
| | - Wolfgang Losert
- Institute for Physical Science and Technology, Department of Physics, University of Maryland, College Park, MD, 20742, USA
| | - Daniel R Larson
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, NCI, NIH, Bethesda, MD, 20892, USA
| | - Carole A Parent
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, 37 Convent Drive, Bldg.37/Rm2066, NCI, NIH, Bethesda, MD, 20892-4256, USA. .,Institute for Physical Science and Technology, Department of Physics, University of Maryland, College Park, MD, 20742, USA.
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19
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Toro-Tapia G, Villaseca S, Leal JI, Beyer A, Fuentealba J, Torrejón M. Xenopus as a model organism to study heterotrimeric G-protein pathway during collective cell migration of neural crest. Genesis 2017; 55. [PMID: 28095644 DOI: 10.1002/dvg.23008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 11/22/2016] [Accepted: 11/24/2016] [Indexed: 01/03/2023]
Abstract
Collective cell migration is essential in many fundamental aspects of normal development, like morphogenesis, organ formation, wound healing, and immune responses, as well as in the etiology of severe pathologies, like cancer metastasis. In spite of the huge amount of data accumulated on cell migration, such a complex process involves many molecular actors, some of which still remain to be functionally characterized. One of these signals is the heterotrimeric G-protein pathway that has been studied mainly in gastrulation movements. Recently we have reported that Ric-8A, a GEF for Gα proteins, plays an important role in neural crest migration in Xenopus development. Xenopus neural crest cells, a highly migratory embryonic cell population induced at the border of the neural plate that migrates extensively in order to differentiate in other tissues during development, have become a good model to understand the dynamics that regulate cell migration. In this review, we aim to provide sufficient evidence supporting how useful Xenopus model with its different tools, such as explants and transplants, paired with improved in vivo imaging techniques, will allow us to tackle the multiple signaling mechanisms involved in neural crest cell migration.
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Affiliation(s)
- G Toro-Tapia
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - S Villaseca
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - J I Leal
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - A Beyer
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - J Fuentealba
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - M Torrejón
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
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Ibo M, Srivastava V, Robinson DN, Gagnon ZR. Cell Blebbing in Confined Microfluidic Environments. PLoS One 2016; 11:e0163866. [PMID: 27706201 PMCID: PMC5051935 DOI: 10.1371/journal.pone.0163866] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 09/15/2016] [Indexed: 11/18/2022] Open
Abstract
Migrating cells can extend their leading edge by forming myosin-driven blebs and F-actin-driven pseudopods. When coerced to migrate in resistive environments, Dictyostelium cells switch from using predominately pseudopods to blebs. Bleb formation has been shown to be chemotactic and can be influenced by the direction of the chemotactic gradient. In this study, we determine the blebbing responses of developed cells of Dictyostelium discoideum to cAMP gradients of varying steepness produced in microfluidic channels with different confining heights, ranging between 1.7 μm and 3.8 μm. We show that microfluidic confinement height, gradient steepness, buffer osmolarity and Myosin II activity are important factors in determining whether cells migrate with blebs or with pseudopods. Dictyostelium cells were observed migrating within the confines of microfluidic gradient channels. When the cAMP gradient steepness is increased from 0.7 nM/μm to 20 nM/μm, cells switch from moving with a mixture of blebs and pseudopods to moving only using blebs when chemotaxing in channels with confinement heights less than 2.4 μm. Furthermore, the size of the blebs increases with gradient steepness and correlates with increases in myosin-II localization at the cell cortex. Reduction of intracellular pressure by high osmolarity buffer or inhibition of myosin-II by blebbistatin leads to a decrease in bleb formation and bleb size. Together, our data reveal that the protrusion type formed by migrating cells can be influenced by the channel height and the steepness of the cAMP gradient, and suggests that a combination of confinement-induced myosin-II localization and cAMP-regulated cortical contraction leads to increased intracellular fluid pressure and bleb formation.
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Affiliation(s)
- Markela Ibo
- Johns Hopkins University, Department of Chemical and Biomolecular Engineering, Baltimore, MD, 21218, United States of America
| | - Vasudha Srivastava
- Johns Hopkins University School of Medicine, Department of Cell Biology, Baltimore, MD, 21205, United States of America
| | - Douglas N. Robinson
- Johns Hopkins University School of Medicine, Department of Cell Biology, Baltimore, MD, 21205, United States of America
| | - Zachary R. Gagnon
- Johns Hopkins University, Department of Chemical and Biomolecular Engineering, Baltimore, MD, 21218, United States of America
- * E-mail:
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21
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Kuburich NA, Adhikari N, Hadwiger JA. Acanthamoeba and Dictyostelium Use Different Foraging Strategies. Protist 2016; 167:511-525. [PMID: 27693864 DOI: 10.1016/j.protis.2016.08.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 08/15/2016] [Accepted: 08/19/2016] [Indexed: 10/21/2022]
Abstract
Amoeba often use cell movement as a mechanism to find food, such as bacteria, in their environment. The chemotactic movement of the soil amoeba Dictyostelium to folate or other pterin compounds released by bacteria is a well-documented foraging mechanism. Acanthamoeba can also feed on bacteria but relatively little is known about the mechanism(s) by which this amoeba locates bacteria. Acanthamoeba movement in the presence of folate or bacteria was analyzed in above agar assays and compared to that observed for Dictyostelium. The overall mobility of Acanthamoeba was robust like that of Dictyostelium but Acanthamoeba did not display a chemotactic response to folate. In the presence of bacteria, Acanthamoeba only showed a marginal bias in directed movement whereas Dictyostelium displayed a strong chemotactic response. A comparison of genomes revealed that Acanthamoeba and Dictyostelium share some similarities in G protein signaling components but that specific G proteins used in Dictyostelium chemotactic responses were not present in current Acanthamoeba genome sequence data. The results of this study suggest that Acanthamoeba does not use chemotaxis as the primary mechanism to find bacterial food sources and that the chemotactic responses of Dictyostelium to bacteria may have co-evolved with chemotactic responses that facilitate multicellular development.
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Affiliation(s)
- Nick A Kuburich
- Department of Microbiology and Molecular Genetics, Oklahoma State University, 307 Life Sciences East, Stillwater, OK 74078-3020, USA
| | - Nirakar Adhikari
- Department of Microbiology and Molecular Genetics, Oklahoma State University, 307 Life Sciences East, Stillwater, OK 74078-3020, USA
| | - Jeffrey A Hadwiger
- Department of Microbiology and Molecular Genetics, Oklahoma State University, 307 Life Sciences East, Stillwater, OK 74078-3020, USA
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22
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Pan M, Xu X, Chen Y, Jin T. Identification of a Chemoattractant G-Protein-Coupled Receptor for Folic Acid that Controls Both Chemotaxis and Phagocytosis. Dev Cell 2016; 36:428-39. [PMID: 26906738 DOI: 10.1016/j.devcel.2016.01.012] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 12/09/2015] [Accepted: 01/19/2016] [Indexed: 10/22/2022]
Abstract
Eukaryotic phagocytes search and destroy invading microorganisms via chemotaxis and phagocytosis. The social amoeba Dictyostelium discoideum is a professional phagocyte that chases bacteria through chemotaxis and engulfs them as food via phagocytosis. G-protein-coupled receptors (GPCRs) are known for detecting chemoattractants and directing cell migration, but their roles in phagocytosis are not clear. Here, we developed a quantitative phosphoproteomic technique to discover signaling components. Using this approach, we discovered the long sought after folic acid receptor, fAR1, in D. discoideum. We showed that the seven-transmembrane receptor fAR1 is required for folic acid-mediated signaling events. Significantly, we discovered that fAR1 is essential for both chemotaxis and phagocytosis of bacteria, thereby representing a chemoattractant GPCR that mediates not only chasing but also ingesting bacteria. We revealed that a phagocyte is able to internalize particles via a chemoattractant-mediated engulfment process. We propose that mammalian phagocytes may also use this mechanism to engulf and ingest bacterial pathogens.
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Affiliation(s)
- Miao Pan
- Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Disease, NIH, Rockville, MD 20852, USA.
| | - Xuehua Xu
- Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Disease, NIH, Rockville, MD 20852, USA
| | - Yong Chen
- Proteomics Core Facility, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Tian Jin
- Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Disease, NIH, Rockville, MD 20852, USA.
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23
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Sohn J, Brick RM, Tuan RS. From embryonic development to human diseases: The functional role of caveolae/caveolin. ACTA ACUST UNITED AC 2016; 108:45-64. [PMID: 26991990 DOI: 10.1002/bdrc.21121] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 02/22/2016] [Indexed: 02/06/2023]
Abstract
Caveolae, an almost ubiquitous, structural component of the plasma membrane, play a critical role in many functions essential for proper cell function, including membrane trafficking, signal transduction, extracellular matrix remodeling, and tissue regeneration. Three main types of caveolin proteins have been identified from caveolae since the discovery of caveolin-1 in the early 1990s. All three (Cav-1, Cav-2, and Cav-3) play crucial roles in mammalian physiology, and can effect pathogenesis in a wide range of human diseases. While many biological activities of caveolins have been uncovered since its discovery, their role and regulation in embryonic develop remain largely poorly understood, although there is increasing evidence that caveolins may be linked to lung and brain birth defects. Further investigations are clearly needed to decipher how caveolae/caveolins mediate cellular functions and activities of normal embryogenesis and how their perturbations contribute to developmental disorders.
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Affiliation(s)
- Jihee Sohn
- Center for Cellular and Molecular Engineering, Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Rachel M Brick
- Center for Cellular and Molecular Engineering, Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Rocky S Tuan
- Center for Cellular and Molecular Engineering, Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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24
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Bhowmik A, Rappel WJ, Levine H. Excitable waves and direction-sensing in Dictyostelium discoideum: steps towards a chemotaxis model. Phys Biol 2016; 13:016002. [PMID: 26824302 PMCID: PMC4887094 DOI: 10.1088/1478-3975/13/1/016002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In recent years, there have been significant advances in our understanding of the mechanisms underlying chemically directed motility by eukaryotic cells such as Dictyostelium. In particular, the local excitation and global inhibition (LEGI) model has proven capable of providing a framework for quantitatively explaining many experiments that present Dictyostelium cells with tailored chemical stimuli and monitor their subsequent polarization. In their natural setting, cells generate their own directional signals via the detection and secretion of cyclic adenosine monophosphate (cAMP). Here, we couple the LEGI approach to an excitable medium model of the cAMP wave-field that is propagated by the cells and investigate the possibility for this class of models to enable accurate chemotaxis to the cAMP waveforms expected in vivo. Our results indicate that the ultra-sensitive version of the model does an excellent job in providing natural wave rectification, thereby providing a compelling solution to the 'back-of-the-wave paradox' during cellular aggregation.
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Affiliation(s)
- Arpan Bhowmik
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77096, USA
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25
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Plattner H. Signalling in ciliates: long- and short-range signals and molecular determinants for cellular dynamics. Biol Rev Camb Philos Soc 2015; 92:60-107. [PMID: 26487631 DOI: 10.1111/brv.12218] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 07/28/2015] [Accepted: 08/21/2015] [Indexed: 12/30/2022]
Abstract
In ciliates, unicellular representatives of the bikont branch of evolution, inter- and intracellular signalling pathways have been analysed mainly in Paramecium tetraurelia, Paramecium multimicronucleatum and Tetrahymena thermophila and in part also in Euplotes raikovi. Electrophysiology of ciliary activity in Paramecium spp. is a most successful example. Established signalling mechanisms include plasmalemmal ion channels, recently established intracellular Ca2+ -release channels, as well as signalling by cyclic nucleotides and Ca2+ . Ca2+ -binding proteins (calmodulin, centrin) and Ca2+ -activated enzymes (kinases, phosphatases) are involved. Many organelles are endowed with specific molecules cooperating in signalling for intracellular transport and targeted delivery. Among them are recently specified soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs), monomeric GTPases, H+ -ATPase/pump, actin, etc. Little specification is available for some key signal transducers including mechanosensitive Ca2+ -channels, exocyst complexes and Ca2+ -sensor proteins for vesicle-vesicle/membrane interactions. The existence of heterotrimeric G-proteins and of G-protein-coupled receptors is still under considerable debate. Serine/threonine kinases dominate by far over tyrosine kinases (some predicted by phosphoproteomic analyses). Besides short-range signalling, long-range signalling also exists, e.g. as firmly installed microtubular transport rails within epigenetically determined patterns, thus facilitating targeted vesicle delivery. By envisaging widely different phenomena of signalling and subcellular dynamics, it will be shown (i) that important pathways of signalling and cellular dynamics are established already in ciliates, (ii) that some mechanisms diverge from higher eukaryotes and (iii) that considerable uncertainties still exist about some essential aspects of signalling.
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Affiliation(s)
- Helmut Plattner
- Department of Biology, University of Konstanz, PO Box M625, 78457, Konstanz, Germany
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26
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Zhu X, Bouffanais R, Yue DKP. Interplay between motility and cell-substratum adhesion in amoeboid cells. BIOMICROFLUIDICS 2015; 9:054112. [PMID: 26487898 PMCID: PMC4592429 DOI: 10.1063/1.4931762] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Accepted: 09/15/2015] [Indexed: 05/07/2023]
Abstract
The effective migration of amoeboid cells requires a fine regulation of cell-substratum adhesion. These entwined processes have been shown to be regulated by a host of biophysical and biochemical cues. Here, we reveal the pivotal role played by calcium-based mechanosensation in the active regulation of adhesion resulting in a high migratory adaptability. Using mechanotactically driven Dictyostelium discoideum amoebae, we uncover the existence of optimal mechanosensitive conditions-corresponding to specific levels of extracellular calcium-for persistent directional migration over physicochemically different substrates. When these optimal mechanosensitive conditions are met, noticeable enhancement in cell migration directionality and speed is achieved, yet with significant differences among the different substrates. In the same narrow range of calcium concentrations that yields optimal cellular mechanosensory activity, we uncovered an absolute minimum in cell-substratum adhesion activity, for all considered substrates, with differences in adhesion strength among them amplified. The blocking of the mechanosensitive ion channels with gadolinium-i.e., the inhibition of the primary mechanosensory apparatus-hampers the active reduction in substrate adhesion, thereby leading to the same undifferentiated and drastically reduced directed migratory response. The adaptive behavioral responses of Dictyostelium cells sensitive to substrates with varying physicochemical properties suggest the possibility of novel surface analyses based on the mechanobiological ability of mechanosensitive and guidable cells to probe substrates at the nanometer-to-micrometer level.
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Affiliation(s)
- Xiaoying Zhu
- Singapore University of Technology and Design , 8 Somapah Road, Singapore 487372
| | - Roland Bouffanais
- Singapore University of Technology and Design , 8 Somapah Road, Singapore 487372
| | - Dick K P Yue
- Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
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27
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Adenylyl cyclase localization to the uropod of aggregating Dictyostelium cells requires RacC. Biochem Biophys Res Commun 2015; 465:613-9. [PMID: 26315268 DOI: 10.1016/j.bbrc.2015.08.072] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 08/17/2015] [Indexed: 11/21/2022]
Abstract
The localization of adenylyl cyclase A (ACA) to uropod of cells is required for the stream formation during Dictyostelium development. RacC is a Dictyostelium orthologue of Cdc42. We identified a streaming defect of racC(-) cells as they are clearly less polarized and form smaller and fragmented streams. ACA-YFP is mainly associated with intracellular vesicular structures, but not with the plasma membrane in racC(-) cells. racC(-) cells have a slightly higher number of vesicles than Ax3 cells, suggesting that the defect of ACA trafficking is not simply due to the lack of vesicle formation. While the ACA-YFP vesicles traveled with an average velocity of 9.1 μm/min in Ax3 cells, a slow and diffusional movement without direction with an average velocity of 4 μm/min was maintained in racC(-) cells. Images acquired by using total internal reflection fluorescence (TIRF) microscopy and fluorescence recovery after photobleaching (FRAP) analysis revealed that a significantly decreased number of ACA-YFP vesicles appeared near the cell membrane, indicating a defect in ACA-YFP vesicle trafficking. These results suggest an important role of RacC in the rapid and directional movements of ACA vesicles on microtubules to the plasma membrane, especially to the back of polarized cell.
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28
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Applications and design of cooperative multi-agent ARN-based systems. Soft comput 2015. [DOI: 10.1007/s00500-014-1330-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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29
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Abstract
UNLABELLED The protozoan parasite Trypanosoma brucei engages in surface-induced social behavior, termed social motility, characterized by single cells assembling into multicellular groups that coordinate their movements in response to extracellular signals. Social motility requires sensing and responding to extracellular signals, but the underlying mechanisms are unknown. Here we report that T. brucei social motility depends on cyclic AMP (cAMP) signaling systems in the parasite's flagellum (synonymous with cilium). Pharmacological inhibition of cAMP-specific phosphodiesterase (PDE) completely blocks social motility without impacting the viability or motility of individual cells. Using a fluorescence resonance energy transfer (FRET)-based sensor to monitor cAMP dynamics in live cells, we demonstrate that this block in social motility correlates with an increase in intracellular cAMP levels. RNA interference (RNAi) knockdown of the flagellar PDEB1 phenocopies pharmacological PDE inhibition, demonstrating that PDEB1 is required for social motility. Using parasites expressing distinct fluorescent proteins to monitor individuals in a genetically heterogeneous community, we found that the social motility defect of PDEB1 knockdowns is complemented by wild-type parasites in trans. Therefore, PDEB1 knockdown cells are competent for social motility but appear to lack a necessary factor that can be provided by wild-type cells. The combined data demonstrate that the role of cyclic nucleotides in regulating microbial social behavior extends to African trypanosomes and provide an example of transcomplementation in parasitic protozoa. IMPORTANCE In bacteria, studies of cell-cell communication and social behavior have profoundly influenced our understanding of microbial physiology, signaling, and pathogenesis. In contrast, mechanisms underlying social behavior in protozoan parasites are mostly unknown. Here we show that social behavior in the protozoan parasite Trypanosoma brucei is governed by cyclic-AMP signaling systems in the flagellum, with intriguing parallels to signaling systems that control bacterial social behavior. We also generated a T. brucei social behavior mutant and found that the mutant phenotype is complemented by wild-type cells grown in the same culture. Our findings open new avenues for dissecting social behavior and signaling in protozoan parasites and illustrate the capacity of these organisms to influence each other's behavior in mixed communities.
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Sgro AE, Schwab DJ, Noorbakhsh J, Mestler T, Mehta P, Gregor T. From intracellular signaling to population oscillations: bridging size- and time-scales in collective behavior. Mol Syst Biol 2015; 11:779. [PMID: 25617347 PMCID: PMC4332153 DOI: 10.15252/msb.20145352] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Collective behavior in cellular populations is coordinated by biochemical signaling networks within individual cells. Connecting the dynamics of these intracellular networks to the population phenomena they control poses a considerable challenge because of network complexity and our limited knowledge of kinetic parameters. However, from physical systems, we know that behavioral changes in the individual constituents of a collectively behaving system occur in a limited number of well-defined classes, and these can be described using simple models. Here, we apply such an approach to the emergence of collective oscillations in cellular populations of the social amoeba Dictyostelium discoideum. Through direct tests of our model with quantitative in vivo measurements of single-cell and population signaling dynamics, we show how a simple model can effectively describe a complex molecular signaling network at multiple size and temporal scales. The model predicts novel noise-driven single-cell and population-level signaling phenomena that we then experimentally observe. Our results suggest that like physical systems, collective behavior in biology may be universal and described using simple mathematical models.
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Affiliation(s)
- Allyson E Sgro
- Joseph Henry Laboratories of Physics, Princeton University, Princeton, NJ, USA Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
| | - David J Schwab
- Joseph Henry Laboratories of Physics, Princeton University, Princeton, NJ, USA Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
| | | | - Troy Mestler
- Joseph Henry Laboratories of Physics, Princeton University, Princeton, NJ, USA
| | - Pankaj Mehta
- Department of Physics, Boston University, Boston, MA, USA
| | - Thomas Gregor
- Joseph Henry Laboratories of Physics, Princeton University, Princeton, NJ, USA Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
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Valignat MP, Nègre P, Cadra S, Lellouch AC, Gallet F, Hénon S, Theodoly O. Lymphocytes can self-steer passively with wind vane uropods. Nat Commun 2014; 5:5213. [PMID: 25323331 DOI: 10.1038/ncomms6213] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 09/09/2014] [Indexed: 01/06/2023] Open
Abstract
A wide variety of cells migrate directionally in response to chemical or mechanical cues, however the mechanisms involved in cue detection and translation into directed movement are debatable. Here we investigate a model of lymphocyte migration on the inner surface of blood vessels. Cells orient their migration against fluid flow, suggesting the existence of an adaptive mechano-tranduction mechanism. We find that flow detection may not require molecular mechano-sensors of shear stress, and detection of flow direction can be achieved by the orientation in the flow of the non-adherent cell rear, the uropod. Uropods act as microscopic wind vanes that can transmit detection of flow direction into cell steering via the on-going machinery of polarity maintenance, without the need for novel internal guidance signalling triggered by flow. Contrary to chemotaxis, which implies active regulation of cue-dependent signalling, upstream flow mechanotaxis of lymphocytes may only rely on a passive self-steering mechanism.
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Affiliation(s)
- Marie-Pierre Valignat
- 1] Laboratory Adhesion &Inflammation, Aix Marseille Université, LAI UM 61, Marseille F-13288, France [2] Inserm, UMR_S 1067, Marseille F-13288, France [3] CNRS, UMR 7333, Marseille F-13288, France
| | - Paulin Nègre
- 1] Laboratory Adhesion &Inflammation, Aix Marseille Université, LAI UM 61, Marseille F-13288, France [2] Inserm, UMR_S 1067, Marseille F-13288, France [3] CNRS, UMR 7333, Marseille F-13288, France [4] APHM, Hôpital de la Conception, Laboratoire d'Immunologie, Marseille F-13385, France
| | - Sophie Cadra
- 1] Laboratory Adhesion &Inflammation, Aix Marseille Université, LAI UM 61, Marseille F-13288, France [2] Inserm, UMR_S 1067, Marseille F-13288, France [3] CNRS, UMR 7333, Marseille F-13288, France
| | - Annemarie C Lellouch
- 1] Laboratory Adhesion &Inflammation, Aix Marseille Université, LAI UM 61, Marseille F-13288, France [2] Inserm, UMR_S 1067, Marseille F-13288, France [3] CNRS, UMR 7333, Marseille F-13288, France
| | - François Gallet
- Université Paris-Diderot, CNRS, MSC UMR 7057, Paris F-75205, France
| | - Sylvie Hénon
- Université Paris-Diderot, CNRS, MSC UMR 7057, Paris F-75205, France
| | - Olivier Theodoly
- 1] Laboratory Adhesion &Inflammation, Aix Marseille Université, LAI UM 61, Marseille F-13288, France [2] Inserm, UMR_S 1067, Marseille F-13288, France [3] CNRS, UMR 7333, Marseille F-13288, France
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32
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Schwebs DJ, Nguyen HN, Miller JA, Hadwiger JA. Loss of cAMP-specific phosphodiesterase rescues spore development in G protein mutant in dictyostelium. Cell Signal 2014; 26:409-18. [PMID: 24511612 DOI: 10.1016/j.cellsig.2013.10.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Cyclic AMP (cAMP) is an important intracellular signaling molecule for many G protein-mediated signaling pathways but the specificity of cAMP signaling in cells with multiple signaling pathways is not well-understood. In Dictyostelium, at least two different G protein signaling pathways, mediated by the Gα2 and Gα4 subunits, are involved with cAMP accumulation, spore production, and chemotaxis and the stimulation of these pathways results in the activation of ERK2, a mitogen-activated protein kinase that can down regulate the cAMP-specific phosphodiesterase RegA. The regA gene was disrupted in gα2(−) and gα4(−) cells to determine if the absence of this phosphodiesterase rescues the development of these G protein mutants as it does for erk2(−) mutants. There gA(−) mutation had no major effects on developmental morphology but enriched the distribution of the Gα mutant cells to the prespore/prestalk border in chimeric aggregates. The loss of RegA function had no effect on Gα4- mediated folate chemotaxis. However, the regA gene disruption in gα4(−) cells, but not in gα2(−) cells, resulted in a substantial rescue and acceleration of spore production. This rescue in sporulation required cell autonomous signaling because the precocious sporulation could not be induced through intercellular signaling in chimeric aggregates. However, intercellular signals from regA(−) strains increased the expression of the prestalk gene ecmB and accelerated the vacuolization of stalk cells. Intercellular signaling from the gα4(−)regA(−) strain did not induce ecmA gene expression indicating cell-type specificity in the promotion of prestalk cell development. regA gene disruption in a Gα4(HC) (Gα4 overexpression) strain did not result in precocious sporulation or stalk cell development indicating that elevated Gα4 subunit expression can mask regA(−) associated phenotypes even when provided with wild-type intercellular signaling. These findings indicate that the Gα2 and Gα4-mediated pathways provide different contributions to the development of spores and stalk cells and that the absence of RegA function can bypass some but not all defects in G protein regulated spore development.
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Sobczyk GJ, Wang J, Weijer CJ. SILAC-based proteomic quantification of chemoattractant-induced cytoskeleton dynamics on a second to minute timescale. Nat Commun 2014; 5:3319. [PMID: 24569529 PMCID: PMC3971484 DOI: 10.1038/ncomms4319] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 01/25/2014] [Indexed: 01/14/2023] Open
Abstract
Cytoskeletal dynamics during cell behaviours ranging from endocytosis and exocytosis to cell division and movement is controlled by a complex network of signalling pathways, the full details of which are as yet unresolved. Here we show that SILAC-based proteomic methods can be used to characterize the rapid chemoattractant-induced dynamic changes in the actin–myosin cytoskeleton and regulatory elements on a proteome-wide scale with a second to minute timescale resolution. This approach provides novel insights in the ensemble kinetics of key cytoskeletal constituents and association of known and novel identified binding proteins. We validate the proteomic data by detailed microscopy-based analysis of in vivo translocation dynamics for key signalling factors. This rapid large-scale proteomic approach may be applied to other situations where highly dynamic changes in complex cellular compartments are expected to play a key role. Actin-dependent motility is driven by the rapid changes in the recruitment of many different structural and regulatory proteins at the cell’s cortex. Sobczyk et al. characterize these changes in the cytoskeletal proteome on a second to minute timescale during chemotactic response in Dictyostelium using SILAC-based proteomics.
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Affiliation(s)
- Grzegorz J Sobczyk
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Jun Wang
- 1] Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK [2]
| | - Cornelis J Weijer
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
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Abstract
The behaviour of an organism often reflects a strategy for coping with its environment. Such behaviour in higher organisms can often be reduced to a few stereotyped modes of movement due to physiological limitations, but finding such modes in amoeboid cells is more difficult as they lack these constraints. Here, we examine cell shape and movement in starved Dictyostelium amoebae during migration toward a chemoattractant in a microfluidic chamber. We show that the incredible variety in amoeboid shape across a population can be reduced to a few modes of variation. Interestingly, cells use distinct modes depending on the applied chemical gradient, with specific cell shapes associated with shallow, difficult-to-sense gradients. Modelling and drug treatment reveals that these behaviours are intrinsically linked with accurate sensing at the physical limit. Since similar behaviours are observed in a diverse range of cell types, we propose that cell shape and behaviour are conserved traits.
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Vinet AF, Fiedler T, Studer V, Froquet R, Dardel A, Cosson P, Pieters J. Initiation of multicellular differentiation in Dictyostelium discoideum is regulated by coronin A. Mol Biol Cell 2014; 25:688-701. [PMID: 24403600 PMCID: PMC3937094 DOI: 10.1091/mbc.e13-04-0219] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Multicellular development of Dictyostelium is induced by starvation and is crucial for its long-term survival. Coronin A mediates the transition from growth to development of the cells and initiates the cAMP-dependent relay by regulating the response to secreted cell density and nutrient deprivation factors. Many biological systems respond to environmental changes by activating intracellular signaling cascades, resulting in an appropriate response. One such system is represented by the social amoeba Dictyostelium discoideum. When food sources become scarce, these unicellular cells can initiate a cAMP-driven multicellular aggregation program to ensure long-term survival. On starvation, the cells secrete conditioned medium factors that initiate cAMP signal transduction by inducing expression of genes such as cAMP receptors and adenylate cyclase. The mechanisms involved in the activation of the first pulses of cAMP release have been unclear. We here show a crucial role for the evolutionarily conserved protein coronin A in the initiation of the cAMP response. On starvation, coronin A–deficient cells failed to up-regulate the expression of cAMP-regulated genes, thereby failing to initiate development, despite a normal prestarvation response. Of importance, external addition of cAMP to coronin A–deficient cells resulted in normal chemotaxis and aggregate formation, thereby restoring the developmental program and suggesting a functional cAMP relay in the absence of coronin A. These results suggest that coronin A is dispensable for cAMP sensing, chemotaxis, and development per se but is part of a signal transduction cascade essential for system initiation leading to multicellular development in Dictyostelium.
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Affiliation(s)
- Adrien F Vinet
- Biozentrum, University of Basel, 4056 Basel, Switzerland Faculty of Medicine, University of Geneva, CH-1211 Geneva 4, Switzerland
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36
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Robery S, Tyson R, Dinh C, Kuspa A, Noegel AA, Bretschneider T, Andrews PLR, Williams RSB. A novel human receptor involved in bitter tastant detection identified using Dictyostelium discoideum. J Cell Sci 2013; 126:5465-76. [PMID: 24006265 PMCID: PMC4376016 DOI: 10.1242/jcs.136440] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/15/2013] [Indexed: 12/19/2022] Open
Abstract
Detection of substances tasting bitter to humans occurs in diverse organisms including the social amoeba Dictyostelium discoideum. To establish a molecular mechanism for bitter tastant detection in Dictyostelium, we screened a mutant library for resistance to a commonly used bitter standard, phenylthiourea. This approach identified a G-protein-coupled receptor mutant, grlJ(-), which showed a significantly increased tolerance to phenylthiourea in growth, survival and movement. This mutant was not resistant to a structurally dissimilar potent bitter tastant, denatonium benzoate, suggesting it is not a target for at least one other bitter tastant. Analysis of the cell-signalling pathway involved in the detection of phenylthiourea showed dependence upon heterotrimeric G protein and phosphatidylinositol 3-kinase activity, suggesting that this signalling pathway is responsible for the cellular effects of phenylthiourea. This is further supported by a phenylthiourea-dependent block in the transient cAMP-induced production of phosphatidylinositol (3,4,5)-trisphosphate (PIP3) in wild-type but not grlJ(-) cells. Finally, we have identified an uncharacterized human protein γ-aminobutyric acid (GABA) type B receptor subunit 1 isoform with weak homology to GrlJ that restored grlJ(-) sensitivity to phenylthiourea in cell movement and PIP3 regulation. Our results thus identify a novel pathway for the detection of the standard bitter tastant phenylthiourea in Dictyostelium and implicate a poorly characterized human protein in phenylthiourea-dependent cell responses.
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Affiliation(s)
- Steven Robery
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Richard Tyson
- Warwick Systems Biology Centre, University of Warwick, Coventry CV4 7AL, UK
| | - Christopher Dinh
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Adam Kuspa
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Angelika A. Noegel
- Institute of Biochemistry I, Medical Faculty, University of Cologne, Cologne, Germany
| | - Till Bretschneider
- Warwick Systems Biology Centre, University of Warwick, Coventry CV4 7AL, UK
| | - Paul L. R. Andrews
- Division of Biomedical Sciences, St George's University of London, London SW17 0RE, UK
| | - Robin S. B. Williams
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK
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37
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Unraveling adaptation in eukaryotic pathways: lessons from protocells. PLoS Comput Biol 2013; 9:e1003300. [PMID: 24204235 PMCID: PMC3812047 DOI: 10.1371/journal.pcbi.1003300] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2013] [Accepted: 09/08/2013] [Indexed: 12/11/2022] Open
Abstract
Eukaryotic adaptation pathways operate within wide-ranging environmental conditions without stimulus saturation. Despite numerous differences in the adaptation mechanisms employed by bacteria and eukaryotes, all require energy consumption. Here, we present two minimal models showing that expenditure of energy by the cell is not essential for adaptation. Both models share important features with large eukaryotic cells: they employ small diffusible molecules and involve receptor subunits resembling highly conserved G-protein cascades. Analyzing the drawbacks of these models helps us understand the benefits of energy consumption, in terms of adjustability of response and adaptation times as well as separation of cell-external sensing and cell-internal signaling. Our work thus sheds new light on the evolution of adaptation mechanisms in complex systems. Adaptation is a common feature in sensory systems, well familiar to us from light and dark adaptation of our visual system. Biological cells, ranging from bacteria to complex eukaryotes, including single-cell organisms and human sensory receptors, adopt different strategies to fulfill this property. However, all of them require substantial amounts of energy to adapt. Here, we compare the different biological strategies and design two minimal models which allow adaptation without requiring energy consumption. Schemes similar to the ones we proposed in our minimal models could have been adopted by ancient protocells, that have evolved into the pathways we now know and study. Analyzing our models can thus help elucidate the advantages brought to the cells by consumption of energy, including the bypassing of hard-wired cell parameters such as diffusion constants with increased control over time scales.
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Abstract
Phosphoinositides (PIs) make up only a small fraction of cellular phospholipids, yet they control almost all aspects of a cell's life and death. These lipids gained tremendous research interest as plasma membrane signaling molecules when discovered in the 1970s and 1980s. Research in the last 15 years has added a wide range of biological processes regulated by PIs, turning these lipids into one of the most universal signaling entities in eukaryotic cells. PIs control organelle biology by regulating vesicular trafficking, but they also modulate lipid distribution and metabolism via their close relationship with lipid transfer proteins. PIs regulate ion channels, pumps, and transporters and control both endocytic and exocytic processes. The nuclear phosphoinositides have grown from being an epiphenomenon to a research area of its own. As expected from such pleiotropic regulators, derangements of phosphoinositide metabolism are responsible for a number of human diseases ranging from rare genetic disorders to the most common ones such as cancer, obesity, and diabetes. Moreover, it is increasingly evident that a number of infectious agents hijack the PI regulatory systems of host cells for their intracellular movements, replication, and assembly. As a result, PI converting enzymes began to be noticed by pharmaceutical companies as potential therapeutic targets. This review is an attempt to give an overview of this enormous research field focusing on major developments in diverse areas of basic science linked to cellular physiology and disease.
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Affiliation(s)
- Tamas Balla
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
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Garciandia A, Suarez T. The NMRA/NMRAL1 homologue PadA modulates the expression of extracellular cAMP relay genes during aggregation in Dictyostelium discoideum. Dev Biol 2013; 381:411-22. [PMID: 23773804 DOI: 10.1016/j.ydbio.2013.06.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 06/04/2013] [Accepted: 06/07/2013] [Indexed: 02/08/2023]
Abstract
NMRA-like proteins belong to a class of conserved transcriptional regulators that function as direct sensors of the metabolic state of the cell and link basic metabolism to changes in gene expression. PadA was the first NMRA-like protein described in Dictyostelium discoideum and was shown to be necessary for prestalk cell differentiation and correct development. We describe and characterize padA(-) mutant phenotype during the onset of development, which results in the formation of abnormally small territories and impairment of cAMP responses. Transcriptional analysis shows that cAMP-induced gene expression is downregulated in padA(-), particularly the genes that establish the extracellular cAMP relay. The mutant phenotype can be rescued with the constitutive expression of one of these genes, carA, encoding the cAMP receptor. Transcriptional analysis of padA(-)/A15::carA showed that carA maximum mRNA levels were not reached during aggregation. Our data support a regulatory role for PadA on the regulation of extracellular cAMP relay genes during aggregation and suggest that PadA is required to achieve carA full induction.
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Affiliation(s)
- Ane Garciandia
- Department of Cellular and Molecular Medicine, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu, 9, 28040 Madrid, Spain
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A Dictyostelium secreted factor requires a PTEN-like phosphatase to slow proliferation and induce chemorepulsion. PLoS One 2013; 8:e59365. [PMID: 23555023 PMCID: PMC3595242 DOI: 10.1371/journal.pone.0059365] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Accepted: 02/13/2013] [Indexed: 02/02/2023] Open
Abstract
In Dictyostelium discoideum, AprA and CfaD are secreted proteins that inhibit cell proliferation. We found that the proliferation of cells lacking CnrN, a phosphatase and tensin homolog (PTEN)-like phosphatase, is not inhibited by exogenous AprA and is increased by exogenous CfaD. The expression of CnrN in cnrN cells partially rescues these altered sensitivities, suggesting that CnrN is necessary for the ability of AprA and CfaD to inhibit proliferation. Cells lacking CnrN accumulate normal levels of AprA and CfaD. Like cells lacking AprA and CfaD, cnrN cells proliferate faster and reach a higher maximum cell density than wild type cells, tend to be multinucleate, accumulate normal levels of mass and protein per nucleus, and form less viable spores. When cnrN cells expressing myc-tagged CnrN are stimulated with a mixture of rAprA and rCfaD, levels of membrane-associated myc-CnrN increase. AprA also causes chemorepulsion of Dictyostelium cells, and CnrN is required for this process. Combined, these results suggest that CnrN functions in a signal transduction pathway downstream of AprA and CfaD mediating some, but not all, of the effects of AprA and CfaD.
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Hadwiger JA. Role of the Vps9-domain protein RgfA in Dictyostelium chemotaxis and development. Can J Microbiol 2013; 59:22-7. [PMID: 23391225 DOI: 10.1139/cjm-2012-0519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Proteins with a Vps9 domain function as guanine nucleotide exchange factors for Rab proteins and can mediate the uptake of cell surface receptors or other molecules through endocytosis. However, genes encoding these proteins have not been previously studied in cells with robust chemotactic capabilities. Several genes encoding Vps9 domains were identified in the genome of Dictyostelium discoideum, and one of the genes, designated as rgfA (DDB_G0272038), was examined for functions in cell growth, development, and chemotaxis. The rgfA gene was expressed during vegetative growth and throughout development, but disruption of this gene resulted in no major alterations in cell growth, macropinocytosis, developmental morphology, or chemotactic movement. However, heterologous expression of RgfA resulted in a delay of developmental morphogenesis and impaired chemotaxis of cells to folate but did not affect macropinocytosis. These results suggest that RgfA might share redundant functions with other Dictyostelium Vps9-domain proteins and that heterologous expression of this protein can alter processes that depend on the reception of external signals.
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Affiliation(s)
- Jeffrey A Hadwiger
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078-3020, USA.
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Glucose and cyclic adenosine monophosphate stimulate activities of adenylate cyclase and guanylate cyclase of Tetrahymena pyriformis infusoria. Bull Exp Biol Med 2012; 152:427-30. [PMID: 22803103 DOI: 10.1007/s10517-012-1545-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
The sensitivities of cyclase enzymes adenylate cyclase and guanylate cyclase to glucose and extracellular cAMP were studied in Tetrahymena pyriformis infusoria. Glucose effectively stimulated activities of both cyclase enzymes, while cAMP more effectively stimulated adenylate cyclase. It was shown that [6-(14)C]glucose specifically bound to Tetrahymena pyriformis infusoria at dissociation constant (K(D)) and number of binding sites (B(max)) 43 nM and 7.53 fmol glucose per 100,000 cells and [8-(3)H]cAMP bound at 19 nM and 4.46 fmol cAMP per 100,000 cells, respectively. Hence, glucose and cAMP specifically bound to Tetrahymena pyriformis cells and stimulated activities of cyclases in these infusoria.
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Srinivasan K, Wright GA, Hames N, Housman M, Roberts A, Aufderheide KJ, Janetopoulos C. Delineating the core regulatory elements crucial for directed cell migration by examining folic-acid-mediated responses. J Cell Sci 2012; 126:221-33. [PMID: 23132928 DOI: 10.1242/jcs.113415] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Dictyostelium discoideum shows chemotaxis towards folic acid (FA) throughout vegetative growth, and towards cAMP during development. We determined the spatiotemporal localization of cytoskeletal and signaling molecules and investigated the FA-mediated responses in a number of signaling mutants to further our understanding of the core regulatory elements that are crucial for cell migration. Proteins enriched in the pseudopods during chemotaxis also relocalize transiently to the plasma membrane during uniform FA stimulation. In contrast, proteins that are absent from the pseudopods during migration redistribute transiently from the PM to the cytosol when cells are globally stimulated with FA. These chemotactic responses to FA were also examined in cells lacking the GTPases Ras C and G. Although Ras and phosphoinositide 3-kinase activity were significantly decreased in Ras G and Ras C/G nulls, these mutants still migrated towards FA, indicating that other pathways must support FA-mediated chemotaxis. We also examined the spatial movements of PTEN in response to uniform FA and cAMP stimulation in phospholipase C (PLC) null cells. The lack of PLC strongly influences the localization of PTEN in response to FA, but not cAMP. In addition, we compared the gradient-sensing behavior of polarized cells migrating towards cAMP to that of unpolarized cells migrating towards FA. The majority of polarized cells make U-turns when the cAMP gradient is switched from the front of the cell to the rear. Conversely, unpolarized cells immediately extend pseudopods towards the new FA source. We also observed that plasma membrane phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P3] levels oscillate in unpolarized cells treated with Latrunculin-A, whereas polarized cells had stable plasma membrane PtdIns(3,4,5)P3 responses toward the chemoattractant gradient source. Results were similar for cells that were starved for 4 hours, with a mixture of polarized and unpolarized cells responding to cAMP. Taken together, these findings suggest that similar components control gradient sensing during FA- and cAMP-mediated motility, but the response of polarized cells is more stable, which ultimately helps maintain their directionality.
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Noratel EF, Petty CL, Kelsey JS, Cost HN, Basappa N, Blumberg DD. The adhesion modulation protein, AmpA localizes to an endocytic compartment and influences substrate adhesion, actin polymerization and endocytosis in vegetative Dictyostelium cells. BMC Cell Biol 2012; 13:29. [PMID: 23126556 PMCID: PMC3586950 DOI: 10.1186/1471-2121-13-29] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 10/22/2012] [Indexed: 11/10/2022] Open
Abstract
Background AmpA is a secreted 24Kd protein that has pleiotropic effects on
Dictyostelium development. Null mutants delay development at
the mound stage with cells adhering too tightly to the substrate. Prestalk
cells initially specify as prespore cells and are delayed in their migration
to the mound apex. Extracellular AmpA can rescue these defects, but AmpA is
also necessary in a cell autonomous manner for anterior
like cells (ALCs) to migrate to the upper cup. The ALCs
are only 10% of the developing cell population making it difficult to study
the cell autonomous effect of AmpA on the migration of these cells. AmpA is
also expressed in growing cells, but, while it contains a hydrophobic leader
sequence that is cleaved, it is not secreted from growing cells. This makes
growing cells an attractive system for studying the cell autonomous function
of AmpA. Results In growing cells AmpA plays an environment dependent role in cell migration.
Excess AmpA facilitates migration on soft, adhesive surfaces but hinders
migration on less adhesive surfaces. AmpA also effects the level of actin
polymerization. Knockout cells polymerize less actin while over expressing
cells polymerize more actin than wild type. Overexpression of AmpA also
causes an increase in endocytosis that is traced to repeated formation of
multiple endocytic cups at the same site on the membrane. Immunofluorescence
analysis shows that AmpA is found in the Golgi and colocalizes with calnexin
and the slow endosomal recycling compartment marker, p25, in a perinuclear
compartment. AmpA is found on the cell periphery and is endocytically
recycled to the perinuclear compartment. Conclusion AmpA is processed through the secretory pathway and traffics to the cell
periphery where it is endocytosed and localizes to what has been defined as
a slow endosomal recycling compartment. AmpA plays a role in actin
polymerization and cell substrate adhesion. Additionally AmpA influences
cell migration in an environment dependent manner. Wild type cells show very
little variation in migration rates under the different conditions examined
here, but either loss or over expression of AmpA cause significant substrate
and environment dependent changes in migration.
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Affiliation(s)
- Elizabeth F Noratel
- Department of Biological Sciences, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
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Read ND, Goryachev AB, Lichius A. The mechanistic basis of self-fusion between conidial anastomosis tubes during fungal colony initiation. FUNGAL BIOL REV 2012. [DOI: 10.1016/j.fbr.2012.02.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Nishimura SI, Ueda M, Sasai M. Non-Brownian dynamics and strategy of amoeboid cell locomotion. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:041909. [PMID: 22680500 DOI: 10.1103/physreve.85.041909] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Indexed: 06/01/2023]
Abstract
Amoeboid cells such as Dictyostelium discoideum and Madin-Darby canine kidney cells show the non-Brownian dynamics of migration characterized by the superdiffusive increase of mean-squared displacement. In order to elucidate the physical mechanism of this non-Brownian dynamics, a computational model is developed which highlights a group of inhibitory molecules for actin polymerization. Based on this model, we propose a hypothesis that inhibitory molecules are sent backward in the moving cell to accumulate at the rear of cell. The accumulated inhibitory molecules at the rear further promote cell locomotion to form a slow positive feedback loop of the whole-cell scale. The persistent straightforward migration is stabilized with this feedback mechanism, but the fluctuation in the distribution of inhibitory molecules and the cell shape deformation concurrently interrupt the persistent motion to turn the cell into a new direction. A sequence of switching behaviors between persistent motions and random turns gives rise to the superdiffusive migration in the absence of the external guidance signal. In the complex environment with obstacles, this combined process of persistent motions and random turns drives the simulated amoebae to solve the maze problem in a highly efficient way, which suggests the biological advantage for cells to bear the non-Brownian dynamics.
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Affiliation(s)
- Shin I Nishimura
- Department of Mathematical and Life Sciences, Hiroshima University, Hiroshima 739-8526, Japan.
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Szabó B, Ünnep R, Markó K, Környei Z, Méhes E, Czirók A. Inhibition of myosin II triggers morphological transition and increased nuclear motility. Cytoskeleton (Hoboken) 2011; 68:325-39. [PMID: 21634026 DOI: 10.1002/cm.20515] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
We investigate the effect of myosin II inhibition on cell shape and nuclear motility in cultures of mouse radial glia-like neural progenitor and rat glioma C6 cells. Instead of reducing nucleokinesis, the myosin II inhibitor blebbistatin provokes an elongated bipolar morphology and increased nuclear motility in both cell types. When myosin II is active, time-resolved traction force measurements indicate a pulling force between the leading edge and the nucleus of C6 cells. In the absence of myosin II activity, traction forces during nucleokinesis are diminished below the sensitivity threshold of our assay. By visualizing the centrosome position in C6 cells with GFP-centrin, we show that in the presence or absence of myosin II activity, the nucleus tends to overtake or lag behind the centrosome, respectively. We interpret these findings with the help of a simple viscoelastic model of the cytoskeleton consisting active contractile and passive compressed elements.
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Affiliation(s)
- Bálint Szabó
- Department of Biological Physics, Eötvös University, 1117 Budapest, Pa´zma´ny P stny 1A, Hungary
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Abstract
Cells recognize external chemical gradients and translate these environmental cues into amplified intracellular signaling that results in elongated cell shape, actin polymerization toward the leading edge, and movement along the gradient. Mechanisms underlying chemotaxis are conserved evolutionarily from Dictyostelium amoeba to mammalian neutrophils. Recent studies have uncovered several parallel intracellular signaling pathways that crosstalk in chemotaxing cells. Here, we review these signaling mechanisms in Dictyostelium discoideum.
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Affiliation(s)
- Yu Wang
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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Sillo A, Matthias J, Konertz R, Bozzaro S, Eichinger L. Salmonella typhimurium is pathogenic for Dictyostelium cells and subverts the starvation response. Cell Microbiol 2011; 13:1793-811. [PMID: 21824247 DOI: 10.1111/j.1462-5822.2011.01662.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In unicellular amoebae, such as Dictyostelium discoideum, bacterial phagocytosis is a food hunting device, while in higher organisms it is the first defence barrier against microbial infection. In both cases, pathogenic bacteria exploit phagocytosis to enter the cell and multiply intracellularly. Salmonella typhimurium, the agent of food-borne gastroenteritis, is phagocytosed by both macrophages and Dictyostelium cells. By using cell biological assays and global transcriptional analysis with DNA microarrays covering the Dictyostelium genome, we show here that S. typhimurium is pathogenic for Dictyostelium cells. Depending on the degree of virulence, which in turn depended on bacterial growth conditions, Salmonella could kill Dictyostelium cells or inhibit their growth and development. In the early phase of infection in non-nutrient buffer, the ingested bacteria escaped degradation, induced a starvation-like transcriptional response but inhibited selectively genes required for chemotaxis and aggregation. This way differentiation of the host cells into spore and stalk cells was blocked or delayed, which in turn is likely to be favourable for the establishment of a replicative niche for Salmonella. Inhibition of the aggregation competence and chemotactic streaming of aggregation-competent cells in the presence of Salmonella suggests interference with cAMP signalling.
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Affiliation(s)
- Alessio Sillo
- Department of Clinical and Biological Sciences, University of Turin, AOU S. Luigi, 10043 Orbassano (Torino), Italy
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Investigating the effect of emetic compounds on chemotaxis in Dictyostelium identifies a non-sentient model for bitter and hot tastant research. PLoS One 2011; 6:e24439. [PMID: 21931717 PMCID: PMC3169598 DOI: 10.1371/journal.pone.0024439] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Accepted: 08/10/2011] [Indexed: 01/05/2023] Open
Abstract
Novel chemical entities (NCEs) may be investigated for emetic liability in a range of unpleasant experiments involving retching, vomiting or conditioned taste aversion/food avoidance in sentient animals. We have used a range of compounds with known emetic /aversive properties to examine the possibility of using the social amoeba, Dictyostelium discoideum, for research into identifying and understanding emetic liability, and hence reduce adverse animal experimentation in this area. Twenty eight emetic or taste aversive compounds were employed to investigate the acute (10 min) effect of compounds on Dictyostelium cell behaviour (shape, speed and direction of movement) in a shallow chemotaxic gradient (Dunn chamber). Compound concentrations were chosen based on those previously reported to be emetic or aversive in in vivo studies and results were recorded and quantified by automated image analysis. Dictyostelium cell motility was rapidly and strongly inhibited by four structurally distinct tastants (three bitter tasting compounds--denatonium benzoate, quinine hydrochloride, phenylthiourea, and the pungent constituent of chilli peppers--capsaicin). In addition, stomach irritants (copper chloride and copper sulphate), and a phosphodiesterase IV inhibitor also rapidly blocked movement. A concentration-dependant relationship was established for five of these compounds, showing potency of inhibition as capsaicin (IC(50) = 11.9 ± 4.0 µM) > quinine hydrochloride (IC(50) = 44.3 ± 6.8 µM) > denatonium benzoate (IC(50) = 129 ± 4 µM) > phenylthiourea (IC(50) = 366 ± 5 µM) > copper sulphate (IC(50) = 1433 ± 3 µM). In contrast, 21 compounds within the cytotoxic and receptor agonist/antagonist classes did not affect cell behaviour. Further analysis of bitter and pungent compounds showed that the effect on cell behaviour was reversible and not cytotoxic, suggesting an uncharacterised molecular mechanism of action for these compounds. These results therefore demonstrate that Dictyostelium has potential as a non-sentient model in the analysis of the molecular effects of tastants, although it has limited utility in identification of emetic agents in general.
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