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Netra P Meena, Alan R Kimmel
Initial immunological defense mechanisms to pathogen invasion rely on innate pathways of chemotaxis and phagocytosis, original to ancient phagocytes. Although chemotaxis has been well-studied in mammalian and model systems using purified chemoattractants in defined conditions, directed movement toward live bacteria has been more difficult to assess. Dictyostelium discoideum is a professional phagocyte that chemotaxes toward bacteria during growth-phase in a process to locate nutrient sources. Using Dictyostelium as a model, we have developed a system that is able to quantify chemotaxis to very high sensitivity...
2018: Frontiers in Cellular and Infection Microbiology
A Leoni Swart, Christopher F Harrison, Ludwig Eichinger, Michael Steinert, Hubert Hilbi
Environmental bacteria of the genus Legionella naturally parasitize free-living amoebae. Upon inhalation of bacteria-laden aerosols, the opportunistic pathogens grow intracellularly in alveolar macrophages and can cause a life-threatening pneumonia termed Legionnaires' disease. Intracellular replication in amoebae and macrophages takes place in a unique membrane-bound compartment, the Legionella -containing vacuole (LCV). LCV formation requires the bacterial Icm/Dot type IV secretion system, which translocates literally hundreds of "effector" proteins into host cells, where they modulate crucial cellular processes for the pathogen's benefit...
2018: Frontiers in Cellular and Infection Microbiology
David J Schwebs, Miao Pan, Nirakar Adhikari, Nick A Kuburich, Tian Jin, Jeffrey A Hadwiger
The Dictyostelium genome encodes only two MAPKs, Erk1 and Erk2, and both are expressed during growth and development. Reduced levels of Erk2 expression have been shown previously to restrict cAMP production during development but still allow for chemotactic movement. In this study the erk2 gene was disrupted to eliminate Erk2 function. The absence of Erk2 resulted in a complete loss of folate and cAMP chemotaxis suggesting that this MAPK plays an integral role in the signaling mechanisms involved with this cellular response...
March 15, 2018: Cellular Signalling
Hoku West-Foyle, Priyanka Kothari, Jonathan Osborne, Douglas N Robinson
The 14-3-3 family comprises a group of small proteins that are essential, ubiquitous, and highly conserved across eukaryotes. Overexpression of the 14-3-3s sigma, epsilon, zeta, and eta correlates with high metastatic potential in multiple cancer types. In Dictyostelium , 14-3-3 promotes myosin II turnover in the cell cortex and modulates cortical tension, cell shape, and cytokinesis. In light of the important roles of 14-3-3 proteins across a broad range of eukaryotic species, we sought to determine how 14-3-3 proteins interact with myosin II...
March 16, 2018: Journal of Biological Chemistry
Christina H Stuelten, Carole A Parent, Denise J Montell
Metastasis remains the greatest challenge in the clinical management of cancer. Cell motility is a fundamental and ancient cellular behaviour that contributes to metastasis and is conserved in simple organisms. In this Review, we evaluate insights relevant to human cancer that are derived from the study of cell motility in non-mammalian model organisms. Dictyostelium discoideum, Caenorhabditis elegans, Drosophila melanogaster and Danio rerio permit direct observation of cells moving in complex native environments and lend themselves to large-scale genetic and pharmacological screening...
March 16, 2018: Nature Reviews. Cancer
Louise P Cramer, Robert R Kay, Evgeny Zatulovskiy
Attractive and repulsive cell guidance is essential for animal life and important in disease. Cell migration toward attractants dominates studies [1-8], but migration away from repellents is important in biology yet relatively little studied [5, 9, 10]. It is widely held that cells initiate migration by protrusion of their front [11-15], yet this has not been explicitly tested for cell guidance because cell margin displacement at opposite ends of the cell has not been distinguished for any cue. We argue that protrusion of the front, retraction of the rear, or both together could in principle break cell symmetry and start migration in response to guidance cues [16]...
March 7, 2018: Current Biology: CB
Christof Litschko, Julia Damiano-Guercio, Stefan Brühmann, Jan Faix
Dictyostelium discoideum has proven to be an excellent model to study amoeboid cell migration. During their life cycle, Dictyostelium cells exhibit distinct modes of motility. Individual growth-phase cells explore new territories by random cell migration using the core cell motility machinery, but they can also hunt bacteria by detection and chemotaxis toward the by-product folate. After depletion of nutrients, the cells initiate a developmental program allowing streaming of the cells into aggregation centers by chemotaxis toward cAMP and by cell-to-cell adhesion...
2018: Methods in Molecular Biology
Ethel Bayer-Santos, Lidia Dos Passos Lima, Lucas de Moraes Ceseti, Camila Yuri Ratagami, Eliane Silva de Santana, Aline Maria da Silva, Chuck Shaker Farah, Cristina Elisa Alvarez-Martinez
Plant-associated bacteria of the genus Xanthomonas cause disease in a wide range of economically important crops. However, their ability to persist in the environment is still poorly understood. Predation by amoebas represent a major selective pressure to bacterial populations in the environment. In this study, we show that the X. citri type 6 secretion system (T6SS) promotes resistance to predation by the soil amoeba Dictyostelium discoideum. We found that an extracytoplasmic function (ECF) sigma factor (EcfK) is required for induction of T6SS genes during interaction with Dictyostelium...
February 28, 2018: Environmental Microbiology
Amotz Zahavi, Keith D Harris, Vidyanand Nanjundiah
In Dictyostelium discoideum , cells that become part of the stalk or basal disc display behaviour that can be interpreted as altruistic. Atzmony et al. (Curr Sci 72:142-145, 1997) had hypothesised that this behaviour could be the outcome of an adaptive strategy based on differing intrinsic quality as reflected by phenotypes that indicate differences in potential for survival and reproduction, followed by intercellular competition among amoebae of differing qualities. Low-quality amoebae would have a poor chance of succeeding in the competition to form spores; they could enhance their chances of survival by adopting a presumptive stalk strategy...
March 2018: Journal of Biosciences
Arjun Srirampur, Ashok Kumar Reddy, Swathi Siva, Anupama Kalwad
No abstract text is available yet for this article.
February 2018: Open Forum Infectious Diseases
Andrés E Marcoleta, Macarena A Varas, Javiera Ortiz-Severín, Leonardo Vásquez, Camilo Berríos-Pastén, Andrea V Sabag, Francisco P Chávez, Miguel L Allende, Carlos A Santiviago, Octavio Monasterio, Rosalba Lagos
Multiresistant and invasive hypervirulent Klebsiella pneumoniae strains have become one of the most urgent bacterial pathogen threats. Recent analyses revealed a high genomic plasticity of this species, harboring a variety of mobile genetic elements associated with virulent strains, encoding proteins of unknown function whose possible role in pathogenesis have not been addressed. K. pneumoniae virulence has been studied mainly in animal models such as mice and pigs, however, practical, financial, ethical and methodological issues limit the use of mammal hosts...
2018: Frontiers in Cellular and Infection Microbiology
Rakesh Kumar, Ranjana Maurya, Shweta Saran
Prostate cancer (PC) is one of the leading cancers in men, raising a serious health issue worldwide. Due to lack of suitable biomarker, their inhibitors and the platform for testing those inhibitors result in poor prognosis of PC. AMPK (AMP-activated protein kinase) is a highly conserved protein kinase found in eukaryotes that is involved in growth and development, and also acts as a therapeutic target for PC. The aim of the present study is to identify novel potent inhibitors of AMPK and propose a simple cellular model system for understanding its biology...
February 15, 2018: Journal of Biomolecular Structure & Dynamics
Kyoung Hwan Lee, Guidenn Sulbarán, Shixin Yang, Ji Young Mun, Lorenzo Alamo, Antonio Pinto, Osamu Sato, Mitsuo Ikebe, Xiong Liu, Edward D Korn, Floyd Sarsoza, Sanford I Bernstein, Raúl Padrón, Roger Craig
Electron microscope studies have shown that the switched-off state of myosin II in muscle involves intramolecular interaction between the two heads of myosin and between one head and the tail. The interaction, seen in both myosin filaments and isolated molecules, inhibits activity by blocking actin-binding and ATPase sites on myosin. This interacting-heads motif is highly conserved, occurring in invertebrates and vertebrates, in striated, smooth, and nonmuscle myosin IIs, and in myosins regulated by both Ca 2+ binding and regulatory light-chain phosphorylation...
February 14, 2018: Proceedings of the National Academy of Sciences of the United States of America
Thomas Pelz, Daniela R Drose, David Fleck, Bastian Henkel, Tobias Ackels, Marc Spehr, Eva M Neuhaus
TMEM16 proteins are a recently identified protein family comprising Ca2+-activated Cl- channels that generate outwardly rectifying ionic currents in response to intracellular Ca2+ elevations. Some TMEM16 family members, such as TMEM16F/ANO6 are also essential for Ca2+-dependent phospholipid scrambling. TMEM16-like genes are present in the genomes of most eukaryotic species, the function(s) of TMEM16 family members from evolutionary ancient eukaryotes is not completely clear. Here, we provide insight into the evolution of these TMEM16 proteins by similarity searches for ancestral sequences...
2018: PloS One
S Honma, K Kouno, S Takasaka, S Mitazaki, S Abe, H Kikuchi, Y Oshima, M Yoshida
Malignant gliomas are highly resistant to chemotherapy and radiation and more effective options for treatment are urgently needed. We reported previously that the aromatic amide brefelamide, which is isolated from methanolic extracts of the cellular slime molds Dictyostelium giganteum and D. brefeldianum, hinders cellular proliferation in a glioma model utilizing 1321N1 human astrocytoma cells. Herein, we examined the mechanisms underlying the inhibition of 1321N1 cell proliferation by brefelamide. Glial cell line-derived neurotrophic factor (GDNF) was found to enhance the rate of proliferation of serum-free cultured 1321N1 cells, but did not affect proliferation in PC12 cells...
January 2, 2018: Die Pharmazie
Mike Friedrich, Revaz Nozadze, Sandra de Keijzer, Ralf Steinmeyer, Vladimir Ermolayev, Gregory S Harms
Single molecule detection and tracking provides at times the only possible method to observe the interactions of low numbers of biomolecules, inlcuding DNA, receptors and signal mediating proteins in living systems. However, most existing imaging methods do not enable both high sensitivity and non-invasive imaging of large specimens. In this study we report a new setup for selective plane illumination microscopy (SPIM), which enables fast imaging and single molecule tracking with the resolution of confocal microscopy and the optical penetration beyond 300 μm...
January 2018: Journal of Fluorescence
Elodie Denet, Valentin Vasselon, Béatrice Burdin, Sylvie Nazaret, Sabine Favre-Bonté
Stenotrophomonas maltophilia is found ubiquitously in the environment and is an important emerging nosocomial pathogen. S. maltophilia has been recently described as an Amoebae-Resistant Bacteria (ARB) that exists as part of the microbiome of various free-living amoebae (FLA) from waters. Co-culture approaches with Vermamoeba vermiformis demonstrated the ability of this bacterium to resist amoebal digestion. In the present study, we assessed the survival and growth of six environmental and one clinical S. maltophilia strains within two amoebal species: Acanthamoeba castellanii and Willaertia magna...
2018: PloS One
Byeonggyu Park, Dong-Yeop Shin, Taeck Joong Jeon
Calcium ions are involved in the regulation of diverse cellular processes. Fourteen genes encoding calcium binding proteins have been identified in Dictyostelium. CBP7, one of the 14 CBPs, is composed of 169 amino acids and contains four EF-hand motifs. Here, we investigated the roles of CBP7 in the development and cell migration of Dictyostelium cells and found that high levels of CBP7 exerted a negative effect on cells aggregation during development, possibly by inhibiting chemoattractant-directed cell migration...
January 29, 2018: Molecules and Cells
Falk Hillmann, Gillian Forbes, Silvia Novohradská, Iuliia Ferling, Konstantin Riege, Marco Groth, Martin Westermann, Manja Marz, Thomas Spaller, Thomas Winckler, Pauline Schaap, Gernot Glöckner
Establishment of multicellularity represents a major transition in eukaryote evolution. A subgroup of Amoebozoa, the dictyosteliids, has evolved a relatively simple aggregative multicellular stage resulting in a fruiting body supported by a stalk. Protosteloid amoeba, which are scattered throughout the amoebozoan tree, differ by producing only one or few single stalked spores. Thus, one obvious difference in the developmental cycle of protosteliids and dictyosteliids seems to be the establishment of multicellularity...
January 25, 2018: Genome Biology and Evolution
Sanea Sheikh, Mats Thulin, James C Cavender, Ricardo Escalante, Shin-Ichi Kawakami, Carlos Lado, John C Landolt, Vidyanand Nanjundiah, David C Queller, Joan E Strassmann, Frederick W Spiegel, Steven L Stephenson, Eduardo M Vadell, Sandra L Baldauf
Traditional morphology-based taxonomy of dictyostelids is rejected by molecular phylogeny. A new classification is presented based on monophyletic entities with consistent and strong molecular phylogenetic support and that are, as far as possible, morphologically recognizable. All newly named clades are diagnosed with small subunit ribosomal RNA (18S rRNA) sequence signatures plus morphological synapomorphies where possible. The two major molecular clades are given the rank of order, as Acytosteliales ord. nov...
November 24, 2017: Protist
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