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Dictyostelium

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https://www.readbyqxmd.com/read/28636923/mechanosensitive-adhesion-explains-stepping-motility-in-amoeboid-cells
#1
Calina A Copos, Sam Walcott, Juan C Del Álamo, Effie Bastounis, Alex Mogilner, Robert D Guy
Cells employing amoeboid motility exhibit repetitive cycles of rapid expansion and contraction and apply coordinated traction forces to their environment. Although aspects of this process are well studied, it is unclear how the cell controls the coordination of cell length changes with adhesion to the surface. Here, we develop a simple model to mechanistically explain the emergence of periodic changes in length and spatiotemporal dynamics of traction forces measured in chemotaxing unicellular amoeba, Dictyostelium discoideum...
June 20, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28633918/traction-force-and-its-regulation-during-cytokinesis-in-dictyostelium-cells
#2
Md Golam Sarowar Jahan, Shigehiko Yumura
Cytokinesis is the final stage of cell division. Dictyostelium cells have multiple modes of cytokinesis, including cytokinesis A, B and C. Cytokinesis A is a conventional mode, which depends on myosin II in the contractile ring. Myosin II null cells divide depending on substratum-attachment (cytokinesis B) or in a multi-polar fashion independent of the cell cycle (cytokinesis C). We investigated the traction stress exerted by dividing cells in the three different modes using traction force microscopy. In all cases, the traction forces were directed inward from both poles...
June 12, 2017: European Journal of Cell Biology
https://www.readbyqxmd.com/read/28632994/role-of-the-small-gtpase-rap1-in-signal-transduction-cell-dynamics-and-bacterial-infection
#3
Hubert Hilbi, Arjan Kortholt
Rap1 belongs to the Ras family of small GTPases, which are involved in a multitude of cellular signal transduction pathways and have extensively been linked to cancer biogenesis and metastasis. The small GTPase is activated in response to various extracellular and intracellular cues. Rap1 has conserved functions in Dictyostelium discoideum amoeba and mammalian cells, which are important for cell polarity, substrate and cell-cell adhesion and other processes that involve the regulation of cytoskeletal dynamics...
June 20, 2017: Small GTPases
https://www.readbyqxmd.com/read/28630813/mutations-in-the-sh1-helix-alter-the-thermal-properties-of-myosin-ii
#4
Kotomi Shibata, Tsubasa Koyama, Shohei Inde, Sosuke Iwai, Shigeru Chaen
The myosin II SH1 helix is a joint that links the converter subdomain to the rest of the myosin motor domain and possibly plays a key role in the arrangement of the converter/lever arm. Several point mutations within the SH1 helix in human myosin IIs have been shown to cause diseases. To reveal whether these SH1 helix mutations affect not only motile activities but also thermal properties of myosin II, here we introduced the E683K or R686C point mutation into the SH1 helix in Dictyostelium myosin II. Thermal inactivation as well as thermal aggregation rates of these mutant proteins demonstrated that these mutations decreased the thermal stability of myosin II...
2017: Biophysics and Physicobiology
https://www.readbyqxmd.com/read/28619991/evidence-that-differentiation-inducing-factor-1-controls-chemotaxis-and-cell-differentiation-at-least-in-part-via-mitochondria-in-d-discoideum
#5
Yuzuru Kubohara, Haruhisa Kikuchi, Van Hai Nguyen, Hidekazu Kuwayama, Yoshiteru Oshima
Differentiation-inducing factor-1 [1-(3,5-dichloro-2,6-dihydroxy-4-methoxyphenyl)hexan-1-one (DIF-1)] is an important regulator of cell differentiation and chemotaxis in the development of the cellular slime mold Dictyostelium discoideum However, the entire signaling pathways downstream of DIF-1 remain to be elucidated. To characterize DIF-1 and its potential receptor(s), we synthesized two fluorescent derivatives of DIF-1, boron-dipyrromethene (BODIPY)-conjugated DIF-1 (DIF-1-BODIPY) and nitrobenzoxadiazole (NBD)-conjugated DIF-1 (DIF-1-NBD), and investigated their biological activities and cellular localization...
June 15, 2017: Biology Open
https://www.readbyqxmd.com/read/28602650/generation-of-single-cell-transcript-variability-by-repression
#6
Vlatka Antolović, Agnes Miermont, Adam M Corrigan, Jonathan R Chubb
Gene expression levels vary greatly within similar cells, even within clonal cell populations [1]. These spontaneous expression differences underlie cell fate diversity in both differentiation and disease [2]. The mechanisms responsible for generating expression variability are poorly understood. Using single-cell transcriptomics, we show that transcript variability emerging during Dictyostelium differentiation is driven predominantly by repression rather than activation. The increased variability of repressed genes was observed over a broad range of expression levels, indicating that variability is actively imposed and not a passive statistical effect of the reduced numbers of molecules accompanying repression...
June 19, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28584190/extracellular-polyphosphate-signals-through-ras-and-akt-to-prime-dictyostelium-discoideum-cells-for-development
#7
Patrick M Suess, Jacob Watson, Wensheng Chen, Richard H Gomer
Linear chains of five to hundreds of phosphates called polyphosphate are found in organisms ranging from bacteria to humans, but their function is poorly understood. In Dictyostelium, polyphosphate is used as a secreted signal that inhibits cytokinesis in an autocrine negative feedback loop. To elucidate how cells respond to this unusual signal, we did proteomic analysis of cells treated with physiological levels of polyphosphate and observed that polyphosphate causes cells to decrease levels of actin cytoskeleton proteins, possibly explaining how polyphosphate inhibits cytokinesis...
June 5, 2017: Journal of Cell Science
https://www.readbyqxmd.com/read/28578698/dictyexpress-a-web-based-platform-for-sequence-data-management-and-analytics-in-dictyostelium-and-beyond
#8
Miha Stajdohar, Rafael D Rosengarten, Janez Kokosar, Luka Jeran, Domen Blenkus, Gad Shaulsky, Blaz Zupan
BACKGROUND: Dictyostelium discoideum, a soil-dwelling social amoeba, is a model for the study of numerous biological processes. Research in the field has benefited mightily from the adoption of next-generation sequencing for genomics and transcriptomics. Dictyostelium biologists now face the widespread challenges of analyzing and exploring high dimensional data sets to generate hypotheses and discovering novel insights. RESULTS: We present dictyExpress (2.0), a web application designed for exploratory analysis of gene expression data, as well as data from related experiments such as Chromatin Immunoprecipitation sequencing (ChIP-Seq)...
June 2, 2017: BMC Bioinformatics
https://www.readbyqxmd.com/read/28556908/hydrophilic-interaction-anion-exchange-for-separation-of-multiply-modified-neutral-and-anionic-dictyostelium-n-glycans
#9
Alba Hykollari, Daniel Malzl, Shi Yan, Iain B H Wilson, Katharina Paschinger
The unusual nature of the N-glycans of the cellular slime mould Dictyostelium discoideum has been revealed by a number of studies, primarily based on examination of radiolabeled glycopeptides but more recently also by MS. The complexity of the N-glycomes of even glycosylation mutants is compounded by the occurrence of anionic modifications, which also present an analytical challenge. In this study, we have employed hydrophilic interaction anion exchange (HIAX) HPLC in combination with MALDI-TOF MS/MS to explore the anionic N-glycome of the M31 (modA) strain, which lacks endoplasmic reticulum α-glucosidase II, an enzyme conserved in most eukaryotes including Homo sapiens...
May 29, 2017: Electrophoresis
https://www.readbyqxmd.com/read/28546289/a-tripeptidyl-peptidase-1-is-a-binding-partner-of-gphr-golgi-ph-regulator-in-dictyostelium
#10
Maria Stumpf, Rolf Müller, Berthold Gaßen, Regina Wehrstedt, Petra Fey, Malte A Karow, Ludwig Eichinger, Gernot Glöckner, Angelika A Noegel
Mutations in tripeptidyl peptidase 1 (TPP1) have been associated with late infantile neuronal ceroid lipofuscinosis (NCL2), a neurodegenerative disorder. TPP1 is a lysosomal serine protease, which removes tripeptides from the amino terminus of proteins and is composed of an N-terminal prodomain and a catalytic domain. It is conserved in mammals, amphibians, fish and the amoeba Dictyostelium discoideum. D. discoideum harbors at least six genes encoding tripeptidyl peptidase 1, tpp1A to tpp1F We identified TPP1F as binding partner of Dictyostelium GPHR (Golgi pH regulator), which is an evolutionary highly conserved intracellular transmembrane protein...
May 25, 2017: Disease Models & Mechanisms
https://www.readbyqxmd.com/read/28545392/adenylyl-cyclase-mrna-localizes-to-the-posterior-of-polarized-dictyostelium-cells-during-chemotaxis
#11
Satarupa Das, Joshua M Parker, Can Guven, Weiye Wang, Paul W Kriebel, Wolfgang Losert, Daniel R Larson, Carole A Parent
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...
May 25, 2017: BMC Cell Biology
https://www.readbyqxmd.com/read/28541182/chemotactic-network-responses-to-live-bacteria-show-independence-of-phagocytosis-from-chemoreceptor-sensing
#12
Netra Pal Meena, Alan R Kimmel
Aspects of innate immunity derive from characteristics inherent to phagocytes, including chemotaxis toward and engulfment of unicellular organisms or cell debris. Ligand chemotaxis has been biochemically investigated using mammalian and model systems, but precision of chemotaxis towards ligands being actively secreted by live bacteria is not well studied, nor has there been systematic analyses of interrelationships between chemotaxis and phagocytosis. The genetic/molecular model Dictyostelium and mammalian phagocytes share mechanistic pathways for chemotaxis and phagocytosis; Dictyostelium chemotax toward bacteria and phagocytose them as food sources...
May 25, 2017: ELife
https://www.readbyqxmd.com/read/28536035/seasonality-can-induce-coexistence-of-multiple-bet-hedging-strategies-in-dictyostelium-discoideum-via-storage-effect
#13
Ricardo Martínez-García, Corina E Tarnita
The social amoeba Dictyostelium discoideum has been recently suggested as an example of bet-hedging in microbes. In the presence of resources, amoebae reproduce as unicellular organisms. Resource depletion, however, leads to a starvation phase in which the population splits between aggregators, which form a fruiting body made of a stalk and resistant spores, and non-aggregators, which remain as vegetative cells. Spores are favored when starvation periods are long, but vegetative cells can exploit resources in environments where food replenishes quickly...
May 20, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28501501/anti-tumor-effects-of-differentiation-inducing-factor-1-in-malignant-melanoma-gsk-3-mediated-inhibition-of-cell-proliferation-and-gsk-3-independent-suppression-of-cell-migration-and-invasion
#14
Masaki Arioka, Fumi Takahashi-Yanaga, Momoko Kubo, Kazunobu Igawa, Katsuhiko Tomooka, Toshiyuki Sasaguri
Differentiation-inducing factor-1 (DIF-1) isolated from Dictyostelium discoideum strongly inhibits the proliferation of various mammalian cells through the activation of glycogen synthase kinase-3 (GSK-3). To evaluate DIF-1 as a novel anti-cancer agent for malignant melanoma, we examined whether DIF-1 has anti-proliferative, anti-migratory, and anti-invasive effects on melanoma cells using in vitro and in vivo systems. DIF-1 reduced the expression levels of cyclin D1 and c-Myc by facilitating their degradation via GSK-3 in mouse (B16BL6) and human (A2058) malignant melanoma cells, and thereby strongly inhibited their proliferation...
May 10, 2017: Biochemical Pharmacology
https://www.readbyqxmd.com/read/28499132/multiple-dictyostelid-species-destroy-biofilms-of-klebsiella-oxytoca-and-other-gram-negative-species
#15
Dean Sanders, Katarzyna D Borys, Fikrullah Kisa, Sheryl A Rakowski, Marcela Lozano, Marcin Filutowicz
Dictyostelids are free-living phagocytes that feed on bacteria in diverse habitats. When bacterial prey is in short supply or depleted, they undergo multicellular development culminating in the formation of dormant spores. In this work, we tested isolates representing four dictyostelid species from two genera (Dictyostelium and Polysphondylium) for the potential to feed on biofilms preformed on glass and polycarbonate surfaces. The abilities of dictyostelids were monitored for three hallmarks of activity: 1) spore germination on biofilms, 2) predation on biofilm enmeshed bacteria by phagocytic cells and 3) characteristic stages of multicellular development (streaming and fructification)...
July 2017: Protist
https://www.readbyqxmd.com/read/28495969/fold-change-detection-and-scale-invariance-of-cell-cell-signaling-in-social-amoeba
#16
Keita Kamino, Yohei Kondo, Akihiko Nakajima, Mai Honda-Kitahara, Kunihiko Kaneko, Satoshi Sawai
Cell-cell signaling is subject to variability in the extracellular volume, cell number, and dilution that potentially increase uncertainty in the absolute concentrations of the extracellular signaling molecules. To direct cell aggregation, the social amoebae Dictyostelium discoideum collectively give rise to oscillations and waves of cyclic adenosine 3',5'-monophosphate (cAMP) under a wide range of cell density. To date, the systems-level mechanism underlying the robustness is unclear. By using quantitative live-cell imaging, here we show that the magnitude of the cAMP relay response of individual cells is determined by fold change in the extracellular cAMP concentrations...
May 23, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28463965/ancient-bacteria-amoeba-relationships-and-pathogenic-animal-bacteria
#17
Joan E Strassmann, Longfei Shu
Long before bacteria infected humans, they infected amoebas, which remain a potentially important reservoir for human disease. Diverse soil amoebas including Dictyostelium and Acanthamoeba can host intracellular bacteria. Though the internal environment of free-living amoebas is similar in many ways to that of mammalian macrophages, they differ in a number of important ways, including temperature. A new study in PLOS Biology by Taylor-Mulneix et al. demonstrates that Bordetella bronchiseptica has two different gene suites that are activated depending on whether the bacterium finds itself in a hot mammalian or cool amoeba host environment...
May 2017: PLoS Biology
https://www.readbyqxmd.com/read/28442431/reducing-isoform-complexity-of-human-tetraspanins-by-optimized-expression-in-dictyostelium-discoideum-enables-high-throughput-functional-read-out
#18
Tineke Scheltz, Julia von Bülow, Eric Beitz
The human tetraspanin family of scaffold proteins comprises 33 isoforms. Being integral membrane proteins, they organize a so-called tetraspanin web via homomeric and heteromeric protein-protein interactions with integrins, immunoglobulins, growth factors, receptor tyrosine kinases, proteases, signaling proteins, and viral capsid proteins. Tetraspanins promote cellular effects, such as adhesion, migration, invasion, signaling, membrane fusion, protein trafficking, cancer progression, and infections. The ubiquitous expression of multiple tetraspanin isoforms and partner proteins hampers specific interaction studies...
April 22, 2017: Protein Expression and Purification
https://www.readbyqxmd.com/read/28424231/mroh1-a-lysosomal-regulator-localized-by-wash-generated-actin
#19
Peter A Thomason, Jason S King, Robert H Insall
The steps leading to constitutive exocytosis are poorly understood. In Dictyostelium WASH complex mutants, exocytosis is blocked, so cells that take up fluorescent dextran from the medium retain it and remain fluorescent. Here, we establish a FACS-based method to select cells that retain fluorescent dextran, allowing identification of mutants with disrupted exocytosis. Screening a pool of random mutants identified members of the WASH complex, as expected, and multiple mutants in the conserved HEAT-repeat-containing protein Mroh1...
May 15, 2017: Journal of Cell Science
https://www.readbyqxmd.com/read/28422986/a-critical-like-collective-state-leads-to-long-range-cell-communication-in-dictyostelium-discoideum-aggregation
#20
Giovanna De Palo, Darvin Yi, Robert G Endres
The transition from single-cell to multicellular behavior is important in early development but rarely studied. The starvation-induced aggregation of the social amoeba Dictyostelium discoideum into a multicellular slug is known to result from single-cell chemotaxis towards emitted pulses of cyclic adenosine monophosphate (cAMP). However, how exactly do transient, short-range chemical gradients lead to coherent collective movement at a macroscopic scale? Here, we developed a multiscale model verified by quantitative microscopy to describe behaviors ranging widely from chemotaxis and excitability of individual cells to aggregation of thousands of cells...
April 2017: PLoS Biology
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