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https://www.readbyqxmd.com/read/28424231/mroh1-a-lysosomal-regulator-localised-by-wash-generated-actin
#1
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 the WASH complex, as expected, and multiple mutants in the conserved HEAT-repeat containing protein Mroh1...
April 19, 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
#2
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
https://www.readbyqxmd.com/read/28415314/cell-alignment-patterns-in-the-collective-migration-of-cells-with-polarized-adhesion
#3
Katsuyoshi Matsushita
Dictyostelium discoideum (Dd) utilizes inhomogeneities in the distribution of cell-cell adhesion molecules on cell membranes for collective cell migration. A simple example of an inhomogeneity is a front-side (leading-edge) polarization in the distribution at the early streaming stage. Experiments have shown that the polarized cell-cell adhesion induces side-by-side contact between cells [Beug et al., Nature (London) 274, 445 (1978)NATUAS0028-083610.1038/274445a0]. This result is counterintuitive, as one would expect cells to align front to front in contact with each other on the basis of front-side polarization...
March 2017: Physical Review. E
https://www.readbyqxmd.com/read/28414774/mycobacterium-marinum-antagonistically-induces-an-autophagic-response-while-repressing-the-autophagic-flux-in-a-torc1-and-esx-1-dependent-manner
#4
Elena Cardenal-Muñoz, Sonia Arafah, Ana Teresa López-Jiménez, Sébastien Kicka, Alexandra Falaise, Frauke Bach, Olivier Schaad, Jason S King, Monica Hagedorn, Thierry Soldati
Autophagy is a eukaryotic catabolic process also participating in cell-autonomous defence. Infected host cells generate double-membrane autophagosomes that mature in autolysosomes to engulf, kill and digest cytoplasmic pathogens. However, several bacteria subvert autophagy and benefit from its machinery and functions. Monitoring infection stages by genetics, pharmacology and microscopy, we demonstrate that the ESX-1 secretion system of Mycobacterium marinum, a close relative to M. tuberculosis, upregulates the transcription of autophagy genes, and stimulates autophagosome formation and recruitment to the mycobacteria-containing vacuole (MCV) in the host model organism Dictyostelium...
April 17, 2017: PLoS Pathogens
https://www.readbyqxmd.com/read/28413119/the-two-dictyostelium-discoideum-autophagy-8-proteins-have-distinct-autophagic-functions
#5
Susanne Meßling, Jan Matthias, Qiuhong Xiong, Sarah Fischer, Ludwig Eichinger
Autophagy is a highly conserved cellular degradation pathway which is crucial for various cellular processes. The autophagic process is subdivided in the initiation, autophagosome maturation and lysosomal degradation phases and involves more than forty core and accessory autophagy-related (ATG) proteins. Autophagy 8 (ATG8, in mammals LC3) is a well-established marker of autophagy and is linked to the autophagic membrane from initiation until fusion with the lysosome. We generated single and double knock-out mutants of the two Dictyostelium paralogues, ATG8a and ATG8b, as well as strains that expressed RFP-ATG8a and/or GFP-ATG8b, RFP-ATG8b, RFP-GFP-ATG8a or RFP-GFP-ATG8b in different knock-out mutants...
April 4, 2017: European Journal of Cell Biology
https://www.readbyqxmd.com/read/28406973/tre5-a-retrotransposition-profiling-reveals-putative-rna-polymerase-iii-transcription-complex-binding-sites-on-the-dictyostelium-extrachromosomal-rdna-element
#6
Thomas Spaller, Marco Groth, Gernot Glöckner, Thomas Winckler
The amoeba Dictyostelium discoideum has a haploid genome in which two thirds of the DNA encodes proteins. Consequently, the space available for selfish mobile elements to expand without excess damage to the host genome is limited. The non-long terminal repeat retrotransposon TRE5-A maintains an active population in the D. discoideum genome and apparently adapted to this gene-dense environment by targeting positions ~47 bp upstream of tRNA genes that are devoid of protein-coding regions. Because only ~24% of tRNA genes are associated with a TRE5-A element in the reference genome, we evaluated whether TRE5-A retrotransposition is limited to this subset of tRNA genes...
2017: PloS One
https://www.readbyqxmd.com/read/28403138/bordetella-bronchiseptica-exploits-the-complex-life-cycle-of-dictyostelium-discoideum-as-an-amplifying-transmission-vector
#7
Dawn L Taylor-Mulneix, Liron Bendor, Bodo Linz, Israel Rivera, Valerie E Ryman, Kalyan K Dewan, Shannon M Wagner, Emily F Wilson, Lindsay J Hilburger, Laura E Cuff, Christopher M West, Eric T Harvill
Multiple lines of evidence suggest that Bordetella species have a significant life stage outside of the mammalian respiratory tract that has yet to be defined. The Bordetella virulence gene (BvgAS) two-component system, a paradigm for a global virulence regulon, controls the expression of many "virulence factors" expressed in the Bvg positive (Bvg+) phase that are necessary for successful respiratory tract infection. A similarly large set of highly conserved genes are expressed under Bvg negative (Bvg-) phase growth conditions; however, these appear to be primarily expressed outside of the host and are thus hypothesized to be important in an undefined extrahost reservoir...
April 2017: PLoS Biology
https://www.readbyqxmd.com/read/28400531/genomics-and-evolution-of-protein-phosphatases
#8
Mark J Chen, Jack E Dixon, Gerard Manning
Protein phosphatases are the essential opposite to protein kinases; together, these enzymes regulate all protein phosphorylation and most cellular processes. To better understand the global roles of protein phosphorylation, we cataloged the human protein phosphatome, composed of 189 known and predicted human protein phosphatase genes. We also identified 79 protein phosphatase pseudogenes or retrogenes, some of which may have residual function. We traced the origin and diversity of phosphatases by building protein phosphatomes for eight other eukaryotes, from the protist Dictyostelium to the sea urchin...
April 11, 2017: Science Signaling
https://www.readbyqxmd.com/read/28395088/neuropathological-hallmarks-of-brain-malformations-in-extreme-phenotypes-related-to-dync1h1-mutations
#9
Annie Laquerriere, Camille Maillard, Mara Cavallin, Françoise Chapon, Florent Marguet, Arnaud Molin, Sabine Sigaudy, Marie Blouet, Guillaume Benoist, Carla Fernandez, Karine Poirier, Jamel Chelly, Sophie Thomas, Nadia Bahi-Buisson
Dyneins play a critical role in a wide variety of cellular functions such as the movement of organelles and numerous aspects of mitosis, making it central player in neocortical neurogenesis and migration. Recently, cytoplasmic dynein-1, heavy chain-1 (DYNC1H1) mutations have been found to cause a wide spectrum of brain cortical malformations. We report on the detailed neuropathological features of brain lesions from 2 fetuses aged 36 and 22 weeks of gestation (WG), respectively, carrying de novo DYNC1H1 mutations, p...
March 1, 2017: Journal of Neuropathology and Experimental Neurology
https://www.readbyqxmd.com/read/28385668/cooperation-induces-other-cooperation-fruiting-bodies-promote-the-evolution-of-macrocysts-in-dictyostelium-discoideum
#10
Shota Shibasaki, Yuka Shirokawa, Masakazu Shimada
Biological studies of the evolution of cooperation are challenging because this process is vulnerable to cheating. Many mechanisms, including kin discrimination, spatial structure, or by-products of self-interested behaviors, can explain this evolution. Here we propose that the evolution of cooperation can be induced by other cooperation. To test this idea, we used a model organism Dictyostelium discoideum because it exhibits two cooperative dormant phases, the fruiting body and the macrocyst. In both phases, the same chemoattractant, cyclic AMP (cAMP), is used to collect cells...
April 4, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28385010/coactosin-like-protein-1-inhibits-the-neuronal-migration-during-mouse-corticogenesis
#11
Guohong Li, Yupeng Yin, Jiong Chen, Yanle Fan, Juhong Ma, Yingxue Huang, Chen Chen, Pengxiu Dai, Shulin Chen, Shanting Zhao
Coactosin-like protein-1 (Cotl1), a member of the actin-depolymerizing factor (ADF)/cofilin family, was first purified from the soluble fraction of Dictyostelium discoideum cells. Neuronal migration requires cytoskeletal remodeling and actin regulation. Although Cotl1 strongly binds to F-actin, the role of Cotl1 in neuronal migration remains unknown. Here, we revealed that Cotl1 overexpression impaired the migration of both early- and late-born neurons during mouse corticogenesis. Moreover, Cotl1 overexpression delayed, rather than blocked, neuronal migration in late-born neurons...
April 6, 2017: Journal of Veterinary Science
https://www.readbyqxmd.com/read/28372375/adaptive-microfluidic-gradient-generator-for-quantitative-chemotaxis-experiments
#12
Alexander Anielski, Eva K B Pfannes, Carsten Beta
Chemotactic motion in a chemical gradient is an essential cellular function that controls many processes in the living world. For a better understanding and more detailed modelling of the underlying mechanisms of chemotaxis, quantitative investigations in controlled environments are needed. We developed a setup that allows us to separately address the dependencies of the chemotactic motion on the average background concentration and on the gradient steepness of the chemoattractant. In particular, both the background concentration and the gradient steepness can be kept constant at the position of the cell while it moves along in the gradient direction...
March 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28365442/loss-of-cln3-impacts-protein-secretion-in-the-social-amoeba-dictyostelium
#13
Robert J Huber
Neuronal ceroid lipofuscinosis (NCL), also referred to as Batten disease, is the most common form of childhood neurodegeneration. Mutations in CLN3 cause the most prevalent subtype of the disease, which manifests during early childhood and is currently untreatable. The precise function of the CLN3 protein is still not known, which has inhibited the development of targeted therapies. In the social amoeba Dictyostelium discoideum, loss of the CLN3 homolog, Cln3, reduces adhesion during early development, which delays streaming and aggregation...
March 29, 2017: Cellular Signalling
https://www.readbyqxmd.com/read/28346441/altering-the-threshold-of-an-excitable-signal-transduction-network-changes-cell-migratory-modes
#14
Yuchuan Miao, Sayak Bhattacharya, Marc Edwards, Huaqing Cai, Takanari Inoue, Pablo A Iglesias, Peter N Devreotes
The diverse migratory modes displayed by different cell types are generally believed to be idiosyncratic. Here we show that the migratory behaviour of Dictyostelium was switched from amoeboid to keratocyte-like and oscillatory modes by synthetically decreasing phosphatidylinositol-4,5-bisphosphate levels or increasing Ras/Rap-related activities. The perturbations at these key nodes of an excitable signal transduction network initiated a causal chain of events: the threshold for network activation was lowered, the speed and range of propagating waves of signal transduction activity increased, actin-driven cellular protrusions expanded and, consequently, the cell migratory mode transitions ensued...
April 2017: Nature Cell Biology
https://www.readbyqxmd.com/read/28330902/regulation-of-nucleosome-positioning-by-a-chd-type-iii-chromatin-remodeler-and-its-relationship-to-developmental-gene-expression-in-dictyostelium
#15
James L Platt, Nicholas A Kent, Alan R Kimmel, Adrian J Harwood
Nucleosome placement and repositioning can direct transcription of individual genes; however, the precise interactions of these events are complex and largely unresolved at the whole-genome level. The Chromodomain-Helicase-DNA binding (CHD) Type III proteins are a subfamily of SWI2/SNF2 proteins that control nucleosome positioning and are associated with several complex human disorders, including CHARGE syndrome and autism. Type III CHDs are required for multicellular development of animals and Dictyostelium but are absent in plants and yeast...
April 2017: Genome Research
https://www.readbyqxmd.com/read/28330789/schiff-bases-of-putrescine-with-methylglyoxal-protect-from-cellular-damage-caused-by-accumulation-of-methylglyoxal-and-reactive-oxygen-species-in-dictyostelium-discoideum
#16
Seong-Jun Park, Min-Kyu Kwak, Sa-Ouk Kang
Polyamines protect protein glycation in cells against the advanced glycation end product precursor methylglyoxal, which is inevitably produced during glycolysis, and the enzymes that detoxify this α-ketoaldehyde have been widely studied. Nonetheless, nonenzymatic methylglyoxal-scavenging molecules have not been sufficiently studied either in vitro or in vivo. Here, we hypothesized reciprocal regulation between polyamines and methylglyoxal modeled in Dictyostelium grown in a high-glucose medium. We based our hypothesis on the reaction between putrescine and methylglyoxal in putrescine-deficient (odc(-)) or putrescine-overexpressing (odc(oe)) cells...
March 19, 2017: International Journal of Biochemistry & Cell Biology
https://www.readbyqxmd.com/read/28302905/protein-kinase-a-regulates-the-ras-rap1-and-torc2-pathways-in-response-to-the-chemoattractant-camp-in-dictyostelium
#17
Margarethakay Scavello, Alexandra R Petlick, Ramya Ramesh, Valery F Thompson, Pouya Lotfi, Pascale G Charest
Efficient directed migration requires tight regulation of chemoattractant signal transduction pathways in both space and time, but the mechanisms involved in such regulation are not well understood. Here, we investigated the role of Protein Kinase A (PKA) in controlling signaling of the chemoattractant cAMP in Dictyostelium We found that cells lacking PKA display severe chemotaxis defects, including impaired directional sensing. Although PKA is an important regulator of developmental gene expression, including the cAMP receptor cAR1, our studies using exogenously expressed cAR1 in cells lacking PKA, cells lacking adenylyl cyclase A (ACA), and cells treated with the PKA-selective pharmacological inhibitor H89, suggest that PKA controls chemoattractant signal transduction, in part, through the regulation of RasG, Rap1, and TORC2...
March 16, 2017: Journal of Cell Science
https://www.readbyqxmd.com/read/28287245/yela-a-putative-dictyostelium-translational-regulator-acts-as-antagonist-of-dif-1-signaling-to-control-cell-type-proportioning
#18
Yoko Yamada, Chris Sugden, Jeffrey G Williams
DIF-1 (differentiation-inducing factor1) is a polyketide produced by Dictyostelium prespore cells which induces initially uncommitted cells to differentiate as prestalk cells. Exposure of cells to DIF-1 causes transitory hypo-phosphorylation of seven serine residues in YelA, a protein with a region of strong homology to the MIF4G domain of the eukaryotic initiation factor eIF4G. Based upon its domain architecture, which in one important aspect closely resembles that of Death-Associated Protein 5 (DAP5), we predict a role in stimulating internal ribosome entry-driven mRNA translation...
2017: International Journal of Developmental Biology
https://www.readbyqxmd.com/read/28272354/micrometer-scale-membrane-transition-of-supported-lipid-bilayer-membrane-reconstituted-with-cytosol-of-dictyostelium-discoideum
#19
Kei Takahashi, Taro Toyota
The transformation of the supported lipid bilayer (SLB) membrane by extracted cytosol from living resources, has recently drawn much attention. It enables us to address the question of whether the purified phospholipid SLB membrane, including lipids related to amoeba locomotion, which was discussed in many previous studies, exhibits membrane deformation in the presence of cytosol extracted from amoeba; Methods: In this report, a method for reconstituting a supported lipid bilayer (SLB) membrane, composed of purified phospholipids and cytosol extracted from Dictyostelium discoideum, is described...
March 7, 2017: Life
https://www.readbyqxmd.com/read/28264855/structural-alteration-of-ompr-as-a-source-of-ertapenem-resistance-in-a-ctx-m-15-producing-escherichia-coli-o25b-h4-st131-clinical-isolate
#20
Hervé Dupont, Pascaline Choinier, David Roche, Sandine Adiba, Megan Sookdeb, Catherine Branger, Erick Denamur, Hedi Mammeri
In this study, an ertapenem-non-susceptible Escherichia coli isolate was investigated to determine the genetic basis for its carbapenem resistance phenotype. This clinical strain was recovered from a patient that received, one year ago, ertapenem to treat a cholangitis due to a carbapenem-susceptible extended-spectrum β-lactamase (ESBL)-producing E. coli isolate. Whole-genome sequencing of these strains was performed using Illumina and single molecule real-time sequencing technologies. It revealed that they belonged to the ST131 clonal group, had the predicted O25b:H4 serotype, and produced the CTX-M-15 and TEM-1 β-lactamases...
March 6, 2017: Antimicrobial Agents and Chemotherapy
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