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Dictyostelium

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https://www.readbyqxmd.com/read/28076662/vps13f-links-bacterial-recognition-and-intracellular-killing-in-dictyostelium
#1
Jade Leiba, Ayman Sabra, Romain Bodinier, Anna Marchetti, Wanessa C Lima, Astrid Melotti, Jackie Perrin, Frederic Burdet, Marco Pagni, Thierry Soldati, Emmanuelle Lelong, Pierre Cosson
Bacterial sensing, ingestion and killing by phagocytic cells are essential processes to protect the human body from infectious microorganisms. The cellular mechanisms involved in intracellular killing, their relative importance, and their specificity towards different bacteria are however poorly defined. In this study, we used Dictyostelium discoideum, a phagocytic cell model amenable to genetic analysis, to identify new gene products involved in intracellular killing. A random genetic screen led us to identify the role of Vps13F in intracellular killing of Klebsiella pneumoniae...
January 11, 2017: Cellular Microbiology
https://www.readbyqxmd.com/read/28074884/actin-interacting-protein-1-contributes-to-intranuclear-rod-assembly-in-dictyostelium-discoideum
#2
Hellen C Ishikawa-Ankerhold, Wioleta Daszkiewicz, Michael Schleicher, Annette Müller-Taubenberger
Intranuclear rods are aggregates consisting of actin and cofilin that are formed in the nucleus in consequence of chemical or mechanical stress conditions. The formation of rods is implicated in a variety of pathological conditions, such as certain myopathies and some neurological disorders. It is still not well understood what exactly triggers the formation of intranuclear rods, whether other proteins are involved, and what the underlying mechanisms of rod assembly or disassembly are. In this study, Dictyostelium discoideum was used to examine appearance, stages of assembly, composition, stability, and dismantling of rods...
January 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28060267/studying-the-protein-quality-control-system-of-d-discoideum-using-temperature-controlled-live-cell-imaging
#3
Liliana Malinovska, Simon Alberti
The complex lifestyle of the social amoebae Dictyostelium discoideum makes it a valuable model for the study of various biological processes. Recently, we showed that D. discoideum is remarkably resilient to protein aggregation and can be used to gain insights into the cellular protein quality control system. However, the use of D. discoideum as a model system poses several challenges to microscopy-based experimental approaches, such as the high motility of the cells and their susceptibility to photo-toxicity...
December 2, 2016: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28057864/adenylate-cyclase-a-acting-on-pka-mediates-induction-of-stalk-formation-by-cyclic-diguanylate-at-the-dictyostelium-organizer
#4
Zhi-Hui Chen, Reema Singh, Christian Cole, Hajara Mohammed Lawal, Christina Schilde, Melanie Febrer, Geoffrey J Barton, Pauline Schaap
Coordination of cell movement with cell differentiation is a major feat of embryonic development. The Dictyostelium stalk always forms at the organizing tip, by a mechanism that is not understood. We previously reported that cyclic diguanylate (c-di-GMP), synthesized by diguanylate cyclase A (DgcA), induces stalk formation. Here we used transcriptional profiling of dgca- structures to identify target genes for c-di-GMP, and used these genes to investigate the c-di-GMP signal transduction pathway. We found that knockdown of cAMP-dependent protein kinase (PKA) activity in prestalk cells reduced stalk gene induction by c-di-GMP, whereas PKA activation bypassed the c-di-GMP requirement for stalk gene expression...
January 5, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28055008/early-nucleolar-disorganization-in-dictyostelium-cell-death
#5
M F Luciani, Y Song, A Sahrane, A Kosta, P Golstein
Cell death occurs in all eukaryotes, but it is still not known whether some core steps of the cell death process are conserved. We investigated this using the protist Dictyostelium. The dissection of events in Dictyostelium vacuolar developmental cell death was facilitated by the sequential requirement for two distinct exogenous signals. An initial exogenous signal (starvation and cAMP) recruited some cells into clumps. Only within these clumps did subsequent cell death events take place. Contrary to our expectations, already this initial signal provoked nucleolar disorganization and irreversible inhibition of rRNA and DNA synthesis, reflecting marked cell dysfunction...
January 5, 2017: Cell Death & Disease
https://www.readbyqxmd.com/read/28049717/a-novel-hect-ubiquitin-ligase-regulating-chemotaxis-and-development-in-dictyostelium-discoideum
#6
Barbara Pergolizzi, Enrico Bracco, Salvatore Bozzaro
Cyclic AMP binding to G protein-coupled receptors orchestrates chemotaxis and development in Dictyostelium. By activating the RasC-TORC2-AKT/PKB module, cAMP regulates cell polarization during chemotaxis. TORC2 also mediates GPCR-dependent stimulation of adenylyl cyclase A (ACA), enhancing cAMP relay and developmental gene expression. Thus, mutants defective in the TORC2 Pia/Rictor subunit are impaired in chemotaxis and development. Near-saturation mutagenesis of a Pia/Rictor mutant by random gene disruption led to selection of two suppressor mutants, in which spontaneous chemotaxis and development were restored...
January 3, 2017: Journal of Cell Science
https://www.readbyqxmd.com/read/28028841/functional-similarities-between-the-dictyostelium-protein-apra-and-the-human-protein-dipeptidyl-peptidase-iv
#7
Sarah E Herlihy, Yu Tang, Jonathan E Phillips, Richard H Gomer
Autocrine proliferation repressor protein A (AprA) is a protein secreted by Dictyostelium discoideum cells. Although there is very little sequence similarity between AprA and any human protein, AprA has a predicted structural similarity to the human protein Dipeptidyl Peptidase IV (DPPIV). AprA is a chemorepellent for Dictyostelium cells, and DPPIV is a chemorepellent for neutrophils. This led us to investigate if AprA and DPPIV have additional functional similarities. We find that like AprA, DPPIV is a chemorepellent for, and inhibits the proliferation of, D...
December 28, 2016: Protein Science: a Publication of the Protein Society
https://www.readbyqxmd.com/read/28027501/disruption-of-homeobox-containing-gene-hbx9-results-in-the-deregulation-of-prestalk-cell-patterning-in-dictyostelium-discoideum
#8
Himanshu Mishra, Pooja Bhadoriya, Shweta Saran
We have earlier classified the homeobox containing genes from Dictyostelium discoideum and identified 5 genes belonging to the TALE class. Here, we have characterized hbx9, a member of TALE class. In situ hybridization results show it to be preferentially expressed in the prestalkA (pstA) cells but not in the prestalkO (pstO) cells. Disruption of the hbx9 gene in Ax2 cells delay initiation of development and also slows cell proliferation. There was decreased cadA expression during the development of hbx9(-) cells, which results in inappropriate cell contacts, altered cell motility and patterning properties...
December 24, 2016: Differentiation; Research in Biological Diversity
https://www.readbyqxmd.com/read/28011630/a-polycycstin-type-transient-receptor-potential-trp-channel-that-is-activated-by-atp
#9
David Traynor, Robert R Kay
ATP and ADP are ancient extra-cellular signalling molecules that in Dictyostelium amoebae cause rapid, transient increases in cytosolic calcium due to an influx through the plasma membrane. This response is independent of hetero-trimeric G-proteins, the putative IP3 receptor IplA and all P2X channels. We show, unexpectedly, that it is abolished in mutants of the polycystin-type transient receptor potential channel, TrpP. Responses to the chemoattractants cyclic-AMP and folic acid are unaffected in TrpP mutants...
December 23, 2016: Biology Open
https://www.readbyqxmd.com/read/27997579/the-c-terminal-synmuv-ddduf926-domain-regulates-the-function-of-the-n-terminal-domain-of-ddnkap
#10
Bhagyashri D Burgute, Vivek S Peche, Rolf Müller, Jan Matthias, Berthold Gaßen, Ludwig Eichinger, Gernot Glöckner, Angelika A Noegel
NKAP (NF-κB activating protein) is a highly conserved SR (serine/arginine-rich) protein involved in transcriptional control and splicing in mammals. We identified DdNKAP, the Dictyostelium discoideum ortholog of mammalian NKAP, as interacting partner of the nuclear envelope protein SUN-1. DdNKAP harbors a number of basic RDR/RDRS repeats in its N-terminal domain and the SynMuv/DUF926 domain at its C-terminus. We describe a novel and direct interaction between DdNKAP and Prp19 (Pre mRNA processing factor 19) which might be relevant for the observed DdNKAP ubiquitination...
2016: PloS One
https://www.readbyqxmd.com/read/27977666/lack-of-ecological-and-life-history-context-can-create-the-illusion-of-social-interactions-in-dictyostelium-discoideum
#11
Ricardo Martínez-García, Corina E Tarnita
Studies of social microbes often focus on one fitness component (reproductive success within the social complex), with little information about or attention to other stages of the life cycle or the ecological context. This can lead to paradoxical results. The life cycle of the social amoeba Dictyostelium discoideum includes a multicellular stage in which not necessarily clonal amoebae aggregate upon starvation to form a possibly chimeric (genetically heterogeneous) fruiting body made of dead stalk cells and spores...
December 2016: PLoS Computational Biology
https://www.readbyqxmd.com/read/27960076/a-plasma-membrane-template-for-macropinocytic-cups
#12
Douwe M Veltman, Thomas D Williams, Gareth Bloomfield, Bi-Chang Chen, Eric Betzig, Robert H Insall, Robert R Kay
Macropinocytosis is a fundamental mechanism that allows cells to take up extracellular liquid into large vesicles. It critically depends on the formation of a ring of protrusive actin beneath the plasma membrane, which develops into the macropinocytic cup. We show that macropinocytic cups in Dictyostelium are organised around coincident intense patches of PIP3, active Ras and active Rac. These signalling patches are invariably associated with a ring of active SCAR/WAVE at their periphery, as are all examined structures based on PIP3 patches, including phagocytic cups and basal waves...
December 13, 2016: ELife
https://www.readbyqxmd.com/read/27932387/the-long-non-coding-rna-transcriptome-of-dictyostelium-discoideum-development
#13
Rafael D Rosengarten, Balaji Santhanam, Janez Kokosar, Gad Shaulsky
Dictyostelium discoideum live in the soil as single cells, engulfing bacteria and growing vegetatively. Upon starvation, tens of thousands of amoebae enter a developmental program that includes aggregation, multicellular differentiation, and sporulation. Major shifts across the protein-coding transcriptome accompany these developmental changes. However, no study has presented a global survey of long non-coding RNAs in D. discoideum To characterize the antisense and long intergenic non-coding RNA transcriptome, we analyzed previously published developmental time course samples using an RNA-sequencing library preparation method that selectively depletes ribosomal RNAs...
December 7, 2016: G3: Genes—Genomes—Genetics
https://www.readbyqxmd.com/read/27923724/strain-specific-impact-of-the-high-pathogenicity-island-on-virulence-in-extra-intestinal-pathogenic-escherichia-coli
#14
Mounira Smati, Giuseppe Magistro, Sandrine Adiba, Andreas Wieser, Bertrand Picard, Sören Schubert, Erick Denamur
In order to clarify the role of the high-pathogenicity island (HPI) in the experimental virulence of Escherichia coli, we constructed different deletion mutants of the entire HPI and of three individual genes (irp2, fyuA and ybtA), encoding for three main functions within the HPI. Those mutants were constructed for three phylogroup B2 strains (536-STc127, CFT073-STc73, and NU14-STc95), representative of the main B2 subgroups causing extra-intestinal infections. Transcriptional profiles obtained for the selected HPI genes irp2, fyuA and ybtA revealed similar patterns for all strains, both under selective iron-deplete conditions and in intracellular bacterial communities in vitro, with a high expression of irp2...
November 22, 2016: International Journal of Medical Microbiology: IJMM
https://www.readbyqxmd.com/read/27919433/sodc-modulates-ras-and-pkb-signaling-in-dictyostelium
#15
Boris Castillo, Seon-Hee Kim, Mujataba Sharief, Tong Sun, Lou W Kim
We have previously reported that the basal RasG activity is aberrantly high in cells lacking Superoxide dismutase C (SodC). Here we report that other Ras proteins such as RasC and RasD activities are not affected in sodC(-) cells and mutagenesis studies showed that the presence of the Cys(118) in the Ras proteins is essential for the superoxide-mediated activation of Ras proteins in Dictyostelium. In addition to the loss of SodC, lack of extracellular magnesium ions increased the level of intracellular superoxide and active RasG proteins...
November 30, 2016: European Journal of Cell Biology
https://www.readbyqxmd.com/read/27911821/myth4-ferm-myosins-have-an-ancient-and-conserved-role-in-filopod-formation
#16
Karl J Petersen, Holly V Goodson, Ashley L Arthur, G W Gant Luxton, Anne Houdusse, Margaret A Titus
The formation of filopodia in Metazoa and Amoebozoa requires the activity of myosin 10 (Myo10) in mammalian cells and of Dictyostelium unconventional myosin 7 (DdMyo7) in the social amoeba Dictyostelium However, the exact roles of these MyTH4-FERM myosins (myosin tail homology 4-band 4.1, ezrin, radixin, moesin; MF) in the initiation and elongation of filopodia are not well defined and may reflect conserved functions among phylogenetically diverse MF myosins. Phylogenetic analysis of MF myosin domains suggests that a single ancestral MF myosin existed with a structure similar to DdMyo7, which has two MF domains, and that subsequent duplications in the metazoan lineage produced its functional homolog Myo10...
December 13, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27881166/using-the-social-amoeba-dictyostelium-to-study-the-functions-of-proteins-linked-to-neuronal-ceroid-lipofuscinosis
#17
REVIEW
Robert J Huber
Neuronal ceroid lipofuscinosis (NCL), also known as Batten disease, is a debilitating neurological disorder that affects both children and adults. Thirteen genetically distinct genes have been identified that when mutated, result in abnormal lysosomal function and an excessive accumulation of ceroid lipofuscin in neurons, as well as other cell types outside of the central nervous system. The NCL family of proteins is comprised of lysosomal enzymes (PPT1/CLN1, TPP1/CLN2, CTSD/CLN10, CTSF/CLN13), proteins that peripherally associate with membranes (DNAJC5/CLN4, KCTD7/CLN14), a soluble lysosomal protein (CLN5), a protein present in the secretory pathway (PGRN/CLN11), and several proteins that display different subcellular localizations (CLN3, CLN6, MFSD8/CLN7, CLN8, ATP13A2/CLN12)...
November 24, 2016: Journal of Biomedical Science
https://www.readbyqxmd.com/read/27872153/xpf-suppresses-the-mutagenic-consequences-of-phagocytosis-in-dictyostelium
#18
Lucas B Pontel, Judith Langenick, Ivan V Rosado, Xiao-Yin Zhang, David Traynor, Robert R Kay, Ketan J Patel
As time passes, mutations accumulate in the genomes of all living organisms. These changes promote genetic diversity, but also precipitate ageing and the initiation of cancer. Food is a common source of mutagens, but little is known about how nutritional factors cause lasting genetic changes in the consuming organism. Here, we describe an unusual genetic interaction between DNA repair in the unicellular amoeba Dictyostelium discoideum and its natural bacterial food source. We found that Dictyostelium deficient in the DNA repair nuclease Xpf (xpf(-)) display a severe and specific growth defect when feeding on bacteria...
December 15, 2016: Journal of Cell Science
https://www.readbyqxmd.com/read/27862766/terpene-cyclases-from-social-amoebae
#19
Patrick Rabe, Jan Rinkel, Britta Nubbemeyer, Tobias G Köllner, Feng Chen, Jeroen S Dickschat
Genome sequences of social amoebae reveal the presence of terpene cyclases (TCs) in these organisms. Two TCs from Dictyostelium discoideum converted farnesyl diphosphate into (2S,3R,6S,9S)-(-)-protoillud-7-ene and (3S)-(+)-asterisca-2(9),6-diene. The enzyme mechanisms and EI-MS fragmentations of the products were studied by labeling experiments.
November 10, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27855631/a-core-phylogeny-of-dictyostelia-inferred-from-genomes-representative-of-the-eight-major-and-minor-taxonomic-divisions-of-the-group
#20
Reema Singh, Christina Schilde, Pauline Schaap
BACKGROUND: Dictyostelia are a well-studied group of organisms with colonial multicellularity, which are members of the mostly unicellular Amoebozoa. A phylogeny based on SSU rDNA data subdivided all Dictyostelia into four major groups, but left the position of the root and of six group-intermediate taxa unresolved. Recent phylogenies inferred from 30 or 213 proteins from sequenced genomes, positioned the root between two branches, each containing two major groups, but lacked data to position the group-intermediate taxa...
November 17, 2016: BMC Evolutionary Biology
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