115 results on '"Schauer K"'
Search Results
2. Peripheral positioning of lysosomes supports melanoma aggressiveness
- Author
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Jerabkova-Roda, K., primary, Mousson, A., additional, Peralta, M., additional, Karali, R., additional, Justiniano, H., additional, Lisii, L.M., additional, Carl, P., additional, Asokan, N., additional, Busnelli, I., additional, Larnicol, A., additional, Lefebvre, O., additional, Lachuer, H., additional, Pichot, A., additional, Stemmelen, T., additional, Molitor, A., additional, Hirschler, A., additional, Delalande, F., additional, Sick, E., additional, Carapito, R., additional, Carapito, C., additional, Hyenne, V., additional, Schauer, K., additional, Rondé, P., additional, and Goetz, J.G., additional
- Published
- 2023
- Full Text
- View/download PDF
3. Persistent cell migration emerges from a coupling between protrusion dynamics and polarized trafficking
- Author
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Vaidžiulytė K, Aude Battistella, Beng W, Anne-Sophie Macé, Mathieu Coppey, and Schauer K
- Subjects
Coupling (electronics) ,Nocodazole ,chemistry.chemical_compound ,chemistry ,Biophysics ,Endomembrane system ,Cell migration ,Context (language use) ,CDC42 ,Optogenetics ,Intracellular - Abstract
Migrating cells present a variety of paths, from non-persistent random walks to highly directional trajectories. While random movement can be easily explained by an intrinsic basal activity of the cell, persistent movement requires the cell to be stably polarized. It remains unclear how this is achieved from the regulation of underlying subcellular processes. In the context of mesenchymal migration, the ability of cells to migrate persistently over several hours require a mechanism stabilizing their protruding activity at their front. Here, we address this mechanism using human RPE1 cell line as our model. We measure, manipulate, and quantitatively perturb cell protrusive activity of the cortex as well as intracellular organization of the endomembrane trafficking system using dynamic micropatterning, pharmacological and trafficking assays, optogenetics and live-cell imaging with tracking. First, we demonstrate that the Nucleus-Golgi axis aligns with the direction of migration and its alignment with the protrusive activity leads to efficient cell movement. Then, using low doses of Nocodazole to disrupt internal cell organization, we show that long-lived polarity breaks down and migration becomes random. Next, we indicate that a flow of vesicles is directed towards the protrusive activity with a delay of 20 min. Eventually, by applying a sustained optogenetic activation, we prove that a localized Cdc42 gradient is able to orient the Nucleus-Golgi axis over a couple of hours. Taken together, our results suggest that the internal polarity axis, provided by the polarized trafficking of vesicles, is stabilizing the protrusive activity of the cell, while the protrusive activity biases this polarity axis. Using a novel minimal physical model, we show that this feedback is sufficient by itself to recapitulate the quantitative properties of cell migration in the timescale of hours. Our work highlights the importance of the coupling between high-level cellular functions in stabilizing the direction of migration over long timescales.
- Published
- 2021
4. Alterations in the equine oocyte and follicle associated with obesity and metabolic syndrome
- Author
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Sessions-Bresnahan, D. R., Schauer, K. L., Heuberger, A. L., Prenni, J. E., and Carnevale, E. M.
- Published
- 2014
- Full Text
- View/download PDF
5. ‘Guilty by Association’ – Protein-Protein Interactions (PPIs) in Bacterial Pathogens
- Author
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Schauer, K., primary and Stingl, K., additional
- Published
- 2009
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6. Structural and mechanistic insights into Helicobacter pylori NikR activation
- Author
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Bahlawane, C., Dian, C., Muller, C., Round, A., Fauquant, C., Schauer, K., de Reuse, H., Terradot, L., and Michaud-Soret, I.
- Published
- 2010
- Full Text
- View/download PDF
7. The H. pylori GroES Co-chaperonin, HspA, Functions as a Specialized Nickel-chaperone and Storage Protein Through its Unique C-terminal Extension: Abstract no.: W8.3
- Author
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Schauer, K., Muller, C., Cavazza, C., Gouget, B., Carriere, M., Labigne, A., and De Reuse, H.
- Published
- 2009
8. Dynamic Load and Strain Analysis for the Optimization of Micro End Mills
- Author
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Uhlmann, E. and Schauer, K.
- Published
- 2005
- Full Text
- View/download PDF
9. Wide-angle X-ray scattering studies on polyethylene at low temperatures
- Author
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Schauer, K. and Wilke, W.
- Published
- 1995
- Full Text
- View/download PDF
10. Gamma Ray Observatory (GRO): Emergency support
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Schauer, K and Madden, J
- Subjects
Astronautics (General) - Abstract
The Gamma Ray Observatory (GRO) is an Earth orbiting satellite that studies sources of localized, galactic, and extragalactic gamma rays. It will be carried into a near-circular orbit by the Space Shuttle, following which it will be placed in its operational orbit by its on-board hydrazine propulsion system. Formal orbit parameters are 350 km x 450 km x 28.5 degrees with a period of 93 minutes. Deep Space Network coverage will be provided during emergencies that would prevent communications via the normal Tracking and Data Relay Satellite System (TDRSS)-White Sands data link. Emergency support will be provided by the DSN's 26-meter antenna subnetwork. Information is given in tabular form for DSN support, frequency assignments, telemetry, and command.
- Published
- 1991
11. A cronobacter turicensis O1 antigen specific monoclonal antibody inhibits bacterial motility and entry into epithelial cells
- Author
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Schauer, K, Lehner, Angelika, Dietrich, R, Kleinsteuber, I, Canals, R, Zurfluh, Katrin, Weiner, K, Märtlbauer, E, University of Zurich, and Schauer, K
- Subjects
2403 Immunology ,2404 Microbiology ,2405 Parasitology ,570 Life sciences ,biology ,610 Medicine & health ,2725 Infectious Diseases ,10082 Institute of Food Safety and Hygiene - Published
- 2015
12. Comparison of technical and commercial aspects regarding cold forming, superplastic forming and hot deep drawing
- Author
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Beck, W., primary, Wagner, S., additional, and Schauer, K., additional
- Published
- 2017
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13. Optimierung von Mikrofräswerkzeugen in der Werkzeugplanungsphase
- Author
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Uhlmann, E., Füting, M., Schauer, K., and Publica
- Subjects
Mikrowerkzeug ,Finite-Elemente-Methode (FEM) ,Schwachstellenanalyse - Abstract
Die Mikrosystemtechnik verlangt auch bei kleinen Stückzahlen wirtschaftliche Fertigungsverfahren, die den Qualitätsanforderungen gerecht werden. In zunehmendem Maße findet hierfür die Mikrozerspanung mit Hartmetallwerkzeugen ihren Einsatz. Diese Technologie bietet neben den Vorteilen der herstellbaren Geometriekomplexität und flexibilität auch die Möglichkeit der Bearbeitung funktionaler Materialien (beispielsweise Stahllegierungen). Grundvoraussetzungen für die Prozesssicherheit dieser Technologie sind hohe Werkzeugstandzeiten sowie die Kenntnis der technologischen Bearbeitungsparameter. Dieser Fachbeitrag zeit Lösungswege, wie die Schwachstellen heutiger Mikrozerspanwerkzeuge, die insbesondere aus ihrer Herstellung resultieren, reduziert und eine sichere Prozessgestaltung für deren Anwendung entwickelt werden können.
- Published
- 2004
14. Structural and mechanistic insights into Helicobacter pylori NikR activation.
- Author
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Bahlawane, Christelle, Dian, C., Muller, Christian, Round, A., Fauquant, C., Schauer, K., de Reuse, H., Terradot, L., Michaud-Soret, I., Bahlawane, Christelle, Dian, C., Muller, Christian, Round, A., Fauquant, C., Schauer, K., de Reuse, H., Terradot, L., and Michaud-Soret, I.
- Abstract
NikR is a transcriptional metalloregulator central in the mandatory response to acidity of Helicobacter pylori that controls the expression of numerous genes by binding to specific promoter regions. NikR/DNA interactions were proposed to rely on protein activation by Ni(II) binding to high-affinity (HA) and possibly secondary external (X) sites. We describe a biochemical characterization of HpNikR mutants that shows that the HA sites are essential but not sufficient for DNA binding, while the secondary external (X) sites and residues from the HpNikR dimer-dimer interface are important for DNA binding. We show that a second metal is necessary for HpNikR/DNA binding, but only to some promoters. Small-angle X-ray scattering shows that HpNikR adopts a defined conformation in solution, resembling the cis-conformation and suggests that nickel does not trigger large conformational changes in HpNikR. The crystal structures of selected mutants identify the effects of each mutation on HpNikR structure. This study unravels key structural features from which we derive a model for HpNikR activation where: (i) HA sites and an hydrogen bond network are required for DNA binding and (ii) metallation of a unique secondary external site (X) modulates HpNikR DNA binding to low-affinity promoters by disruption of a salt bridge.
- Published
- 2010
- Full Text
- View/download PDF
15. Structural and mechanistic insights into Helicobacter pylori NikR function
- Author
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Dian, C., primary, Bahlawane, C., additional, Muller, C., additional, Round, A., additional, Delay, C., additional, Fauquant, C., additional, Schauer, K., additional, de Reuse, H., additional, Michaud-Soret, I., additional, and Terradot, L., additional
- Published
- 2010
- Full Text
- View/download PDF
16. apo-NIKR from helicobacter pylori in closed trans-conformation
- Author
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Dian, C., primary, Schauer, K., additional, Kapp, U., additional, McSweeney, S.M., additional, Labigne, A., additional, and Terradot, L., additional
- Published
- 2006
- Full Text
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17. Innovative Fräswerkzeuge für die Mikrozerspanung
- Author
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Uhlmann, E., primary, Oberschmidt, D., additional, and Schauer, K., additional
- Published
- 2006
- Full Text
- View/download PDF
18. Optimierung von Mikrofräswerkzeugen in der Werkzeugplanungsphase – Nutzung innovativer Technologien zur Verbesserung der Prozesssicherheit von Mikrofräswerkzeugen
- Author
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Uhlmann, E., primary, Füting, M., additional, and Schauer, K., additional
- Published
- 2004
- Full Text
- View/download PDF
19. Endbearbeitung von Mikrofräsern mittels Ionenstrahltechniken
- Author
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Borek, S., primary, Schauer, K., additional, Füting, M., additional, and Heilmann, A., additional
- Published
- 2004
- Full Text
- View/download PDF
20. Einsatz von Wolfram‐Kupfer‐Verbundwerkstoffen für Elektroden im Mikro‐Werkzeug‐ und Formenbau
- Author
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Uhlmann, E., primary, Doll, U., additional, Piltz, S., additional, and Schauer, K., additional
- Published
- 2003
- Full Text
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21. Dynamische Werkzeuganalysen in der Mikrozerspanung – Beurteilung des dynamischen Verhaltens von Mikrofräswerkzeugen mit einem Einpunkt-Laservibrometer
- Author
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Uhlmann, E., primary, Piltz, S., additional, and Schauer, K., additional
- Published
- 2003
- Full Text
- View/download PDF
22. Mikrozerspanung metallischer Verbundwerkstoffe
- Author
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Uhlmann, E., primary, Piltz, S., additional, and Schauer, K., additional
- Published
- 2002
- Full Text
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23. Deciphering the intracellular metabolism of Listeria monocytogenes by mutant screening and modelling
- Author
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Dandekar Thomas, Goebel Werner, Liang Chunguang, Geginat Gernot, Schauer Kristina, and Fuchs Thilo M
- Subjects
Biotechnology ,TP248.13-248.65 ,Genetics ,QH426-470 - Abstract
Abstract Background The human pathogen Listeria monocytogenes resides and proliferates within the cytoplasm of epithelial cells. While the virulence factors essentially contributing to this step of the infection cycle are well characterized, the set of listerial genes contributing to intracellular replication remains to be defined on a genome-wide level. Results A comprehensive library of L. monocytogenes strain EGD knockout mutants was constructed upon insertion-duplication mutagenesis, and 1491 mutants were tested for their phenotypes in rich medium and in a Caco-2 cell culture assay. Following sequencing of the plasmid insertion site, 141 different genes required for invasion of and replication in Caco-2 cells were identified. Ten in-frame deletion mutants were constructed that confirmed the data. The genes with known functions are mainly involved in cellular processes including transport, in the intermediary metabolism of sugars, nucleotides and lipids, and in information pathways such as regulatory functions. No function could be ascribed to 18 genes, and a counterpart of eight genes is missing in the apathogenic species L. innocua. Mice infection studies revealed the in vivo requirement of IspE (Lmo0190) involved in mevalonate synthesis, and of the novel ABC transporter Lmo0135-0137 associated with cysteine transport. Based on the data of this genome-scale screening, an extreme pathway and elementary mode analysis was applied that demonstrates the critical role of glycerol and purine metabolism, of fucose utilization, and of the synthesis of glutathione, aspartate semialdehyde, serine and branched chain amino acids during intracellular replication of L. monocytogenes. Conclusion The combination of a genetic screening and a modelling approach revealed that a series of transporters help L. monocytogenes to overcome a putative lack of nutrients within cells, and that a high metabolic flexibility contributes to the intracellular replication of this pathogen.
- Published
- 2010
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- View/download PDF
24. Ecoprofit-Styria-prepare Thirteen pollution prevention case studies in the Styrian industry
- Author
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Altenburger, J., Dielacher, Th., Eder, P., Ferner, H., Fegerl, M., Fresner, J., Gelinek, O., Kogler, A., Jantschgi, J., Nussbaumer, M., Russegger, B., Schnitzer, H., Schauer, K., Sebesta, B., Seiler, J., Sprenger, F., and Widenmeyer, H.
- Published
- 1994
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25. Association of ectomycorrhizal mats with Pacific yew and other understory trees in coniferous forests
- Author
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Robatzek, M., Schadwick, A. C., Schaffroth, K. A., Griffiths, R. P., and Schauer, K.
- Subjects
FORESTS & forestry ,FUNGI - Published
- 1995
26. Aficamten is a small-molecule cardiac myosin inhibitor designed to treat hypertrophic cardiomyopathy.
- Author
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Hartman JJ, Hwee DT, Robert-Paganin J, Chuang C, Chin ER, Edell S, Lee KH, Madhvani R, Paliwal P, Pernier J, Sarkar SS, Schaletzky J, Schauer K, Taheri KD, Wang J, Wehri E, Wu Y, Houdusse A, Morgan BP, and Malik FI
- Subjects
- Animals, Humans, Disease Models, Animal, Myocytes, Cardiac drug effects, Myocytes, Cardiac metabolism, Mice, Crystallography, X-Ray, Mutation, Sarcomeres metabolism, Sarcomeres drug effects, Actins metabolism, Models, Molecular, Mice, Transgenic, Protein Conformation, Cardiomyopathy, Hypertrophic drug therapy, Cardiomyopathy, Hypertrophic metabolism, Myocardial Contraction drug effects, Cardiac Myosins metabolism, Cardiac Myosins genetics
- Abstract
Hypertrophic cardiomyopathy (HCM) is an inherited disease of the sarcomere resulting in excessive cardiac contractility. The first-in-class cardiac myosin inhibitor, mavacamten, improves symptoms in obstructive HCM. Here we present aficamten, a selective small-molecule inhibitor of cardiac myosin that diminishes ATPase activity by strongly slowing phosphate release, stabilizing a weak actin-binding state. Binding to an allosteric site on the myosin catalytic domain distinct from mavacamten, aficamten prevents the conformational changes necessary to enter the strongly actin-bound force-generating state. In doing so, aficamten reduces the number of functional myosin heads driving sarcomere shortening. The crystal structure of aficamten bound to cardiac myosin in the pre-powerstroke state provides a basis for understanding its selectivity over smooth and fast skeletal muscle. Furthermore, in cardiac myocytes and in mice bearing the hypertrophic R403Q cardiac myosin mutation, aficamten reduces cardiac contractility. Our findings suggest aficamten holds promise as a therapy for HCM., (© 2024. The Author(s).)
- Published
- 2024
- Full Text
- View/download PDF
27. The paracaspase MALT1 controls cholesterol homeostasis in glioblastoma stem-like cells through lysosome proteome shaping.
- Author
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Maghe C, Trillet K, André-Grégoire G, Kerhervé M, Merlet L, Jacobs KA, Schauer K, Bidère N, and Gavard J
- Subjects
- Humans, Proteome metabolism, Carrier Proteins metabolism, Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein metabolism, Intracellular Signaling Peptides and Proteins metabolism, Homeostasis, Lysosomes metabolism, Cholesterol metabolism, Glioblastoma genetics, Glioblastoma metabolism, Niemann-Pick Disease, Type C metabolism
- Abstract
Glioblastoma stem-like cells (GSCs) compose a tumor-initiating and -propagating population remarkably vulnerable to variation in the stability and integrity of the lysosomal compartment. Previous work has shown that the expression and activity of the paracaspase MALT1 control GSC viability via lysosome abundance. However, the underlying mechanisms remain elusive. By combining RNA sequencing (RNA-seq) with proteome-wide label-free quantification, we now report that MALT1 repression in patient-derived GSCs alters the homeostasis of cholesterol, which accumulates in late endosomes (LEs)-lysosomes. This failure in cholesterol supply culminates in cell death and autophagy defects, which can be partially reverted by providing exogenous membrane-permeable cholesterol to GSCs. From a molecular standpoint, a targeted lysosome proteome analysis unraveled that Niemann-Pick type C (NPC) lysosomal cholesterol transporters are diluted when MALT1 is impaired. Accordingly, we found that NPC1/2 inhibition and silencing partially mirror MALT1 loss-of-function phenotypes. This supports the notion that GSC fitness relies on lysosomal cholesterol homeostasis., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)
- Published
- 2024
- Full Text
- View/download PDF
28. Draft genome sequences of two thermophilic, spore-forming Aeribacillus pallidus strains isolated from dairy products.
- Author
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Lücking G, Albrecht K, Märtlbauer E, and Schauer K
- Abstract
The presence of thermophilic spore-forming bacteria is challenging in industrial food processing. The presented genome sequences of Aeribacillus pallidus , isolated from raw milk and cocoa powder, provide insights into how to prevent damage to minimally processed foods and products with extended shelf life, such as milk products., Competing Interests: The authors declare no conflict of interest.
- Published
- 2024
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29. Plasmid-encoded lactose metabolism and mobilized colistin resistance ( mcr-9 ) genes in Salmonella enterica serovars isolated from dairy facilities in the 1980s.
- Author
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Kröger C, Lerminiaux NA, Ershova AS, MacKenzie KD, Kirzinger MW, Märtlbauer E, Perry BJ, Cameron ADS, and Schauer K
- Subjects
- Lactose, Serogroup, Drug Resistance, Bacterial genetics, Plasmids genetics, Colistin pharmacology, Salmonella enterica genetics
- Abstract
Horizontal gene transfer by plasmids can confer metabolic capabilities that expand a host cell's niche. Yet, it is less understood whether the coalescence of specialized catabolic functions, antibiotic resistances and metal resistances on plasmids provides synergistic benefits. In this study, we report whole-genome assembly and phenotypic analysis of five Salmonella enterica strains isolated in the 1980s from milk powder in Munich, Germany. All strains exhibited the unusual phenotype of lactose-fermentation and encoded either of two variants of the lac operon. Surprisingly, all strains encoded the mobilized colistin resistance gene 9 ( mcr-9 ), long before the first report of this gene in the literature. In two cases, the mcr-9 gene and the lac locus were linked within a large gene island that formed an IncHI2A-type plasmid in one strain but was chromosomally integrated in the other strain. In two other strains, the mcr-9 gene was found on a large IncHI1B/IncP-type plasmid, whereas the lac locus was encoded on a separate chromosomally integrated plasmidic island. The mcr-9 sequences were identical and genomic contexts could not explain the wide range of colistin resistances exhibited by the Salmonella strains. Nucleotide variants did explain phenotypic differences in motility and exopolysaccharide production. The observed linkage of mcr-9 to lactose metabolism, an array of heavy-metal detoxification systems, and other antibiotic resistance genes may reflect a coalescence of specialized phenotypes that improve the spread of colistin resistance in dairy facilities, much earlier than previously suspected.
- Published
- 2023
- Full Text
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30. Native top-down proteomics reveals EGFR-ERα signaling crosstalk in breast cancer cells dissociates NUTF2 dimers to modulate ERα signaling and cell growth.
- Author
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Yates J 3rd, Gomes F, Durbin K, Schauer K, Nwachukwu J, Russo R, Njeri J, Saviola A, McClatchy D, Diedrich J, Garrett P, Papa A, Ciolacu I, Kelleher N, and Nettles K
- Abstract
Oligomerization of proteins and their modified forms (proteoforms) produces functional protein complexes
1,2 . Complexoforms are complexes that consist of the same set of proteins with different proteoforms3 . The ability to characterize these assemblies within cells is critical to understanding the molecular mechanisms involved in disease and to designing effective drugs. An outstanding biological question is how proteoforms drive function and oligomerization of complexoforms. However, tools to define endogenous proteoform-proteoform/ligand interactions are scarce4 . Here, we present a native top-down proteomics (nTDP) strategy that combines size-exclusion chromatography, nano liquid-chromatography in direct infusion mode, field asymmetric ion mobility spectrometry, and multistage mass spectrometry to identify protein assemblies (≤70 kDa) in breast cancer cells and in cells that overexpress EGFR, a resistance model of estrogen receptor-α (ER-α) targeted therapies. By identifying ~104 complexoforms from 17 protein complexes, our nTDP approach revealed several molecular features of the breast cancer proteome, including EGFR-induced dissociation of nuclear transport factor 2 (NUTF2) assemblies that modulate ER activity. Our findings show that the K4 and K55 posttranslational modification sites discovered with nTDP differentially impact the effects of NUTF2 on the inhibition of the ER signaling pathway. By characterizing endogenous proteoform-proteoform/ligand interactions, we reveal the molecular diversity of complexoforms, which allows us to propose a model for ER drug discovery in the context of designing effective inhibitors to selectively bind and disrupt the actions of targeted ER complexoforms., Competing Interests: Competing Interests: KRD and NLK are involved in the commercialization of top-down proteomics software including ProSight Native. The other authors have no competing interests to disclose.- Published
- 2023
- Full Text
- View/download PDF
31. Spatial organization of lysosomal exocytosis relies on membrane tension gradients.
- Author
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Lachuer H, Le L, Lévêque-Fort S, Goud B, and Schauer K
- Subjects
- Cell Membrane metabolism, Membranes, Lysosomes metabolism, Exocytosis physiology, Cell Physiological Phenomena
- Abstract
Lysosomal exocytosis is involved in many key cellular processes but its spatiotemporal regulation is poorly known. Using total internal reflection fluorescence microscopy (TIRFM) and spatial statistics, we observed that lysosomal exocytosis is not random at the adhesive part of the plasma membrane of RPE1 cells but clustered at different scales. Although the rate of exocytosis is regulated by the actin cytoskeleton, neither interfering with actin or microtubule dynamics by drug treatments alters its spatial organization. Exocytosis events partially co-appear at focal adhesions (FAs) and their clustering is reduced upon removal of FAs. Changes in membrane tension following a hypo-osmotic shock or treatment with methyl-β-cyclodextrin were found to increase clustering. To investigate the link between FAs and membrane tension, cells were cultured on adhesive ring-shaped micropatterns, which allow to control the spatial organization of FAs. By using a combination of TIRFM and fluorescence lifetime imaging microscopy (FLIM), we revealed the existence of a radial gradient in membrane tension. By changing the diameter of micropatterned substrates, we further showed that this gradient as well as the extent of exocytosis clustering can be controlled. Together, our data indicate that the spatial clustering of lysosomal exocytosis relies on membrane tension patterning controlled by the spatial organization of FAs.
- Published
- 2023
- Full Text
- View/download PDF
32. Transcription factor EB regulates phosphatidylinositol-3-phosphate levels that control lysosome positioning in the bladder cancer model.
- Author
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Mathur P, De Barros Santos C, Lachuer H, Patat J, Latgé B, Radvanyi F, Goud B, and Schauer K
- Subjects
- Humans, Lysosomes metabolism, Phosphates metabolism, Phosphatidylinositol Phosphates metabolism, Urinary Bladder Neoplasms genetics, Urinary Bladder Neoplasms metabolism, Basic Helix-Loop-Helix Leucine Zipper Transcription Factors genetics, Basic Helix-Loop-Helix Leucine Zipper Transcription Factors metabolism
- Abstract
Lysosomes orchestrate degradation and recycling of exogenous and endogenous material thus controlling cellular homeostasis. Little is known how this organelle changes during cancer. Here we investigate the intracellular landscape of lysosomes in a cellular model of bladder cancer. Employing standardized cell culture on micropatterns we identify a phenotype of peripheral lysosome positioning prevailing in bladder cancer cell lines but not normal urothelium. We show that lysosome positioning is controlled by phosphatidylinositol-3-phosphate (PtdIns3P) levels on endomembranes which recruit FYVE-domain containing proteins for lysosomal dispersion. We identify transcription factor EB (TFEB) as an upstream regulator of PtdIns3P production by VPS34 that is activated in aggressive bladder cancer cells with peripheral lysosomes. This conceptually clarifies the dual role of TFEB as regulator of endosomal maturation and autophagy, two distinct processes controlled by PtdIns3P. Altogether, our findings uncover peripheral lysosome positioning, resulting from PtdIns3P production downstream of TFEB activation, as a potential biomarker for bladder cancer., (© 2023. The Author(s).)
- Published
- 2023
- Full Text
- View/download PDF
33. Does the Actin Network Architecture Leverage Myosin-I Functions?
- Author
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Pernier J and Schauer K
- Abstract
The actin cytoskeleton plays crucial roles in cell morphogenesis and functions. The main partners of cortical actin are molecular motors of the myosin superfamily. Although our understanding of myosin functions is heavily based on myosin-II and its ability to dimerize, the largest and most ancient class is represented by myosin-I. Class 1 myosins are monomeric, actin-based motors that regulate a wide spectrum of functions, and whose dysregulation mediates multiple human diseases. We highlight the current challenges in identifying the "pantograph" for myosin-I motors: we need to reveal how conformational changes of myosin-I motors lead to diverse cellular as well as multicellular phenotypes. We review several mechanisms for scaling, and focus on the (re-) emerging function of class 1 myosins to remodel the actin network architecture, a higher-order dynamic scaffold that has potential to leverage molecular myosin-I functions. Undoubtfully, understanding the molecular functions of myosin-I motors will reveal unexpected stories about its big partner, the dynamic actin cytoskeleton.
- Published
- 2022
- Full Text
- View/download PDF
34. Persistent cell migration emerges from a coupling between protrusion dynamics and polarized trafficking.
- Author
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Vaidžiulytė K, Macé AS, Battistella A, Beng W, Schauer K, and Coppey M
- Subjects
- Cell Movement physiology, Cell Polarity physiology, Golgi Apparatus
- Abstract
Migrating cells present a variety of paths, from random to highly directional ones. While random movement can be explained by basal intrinsic activity, persistent movement requires stable polarization. Here, we quantitatively address emergence of persistent migration in (hTERT)-immortalizedRPE1 (retinal pigment epithelial) cells over long timescales. By live cell imaging and dynamic micropatterning, we demonstrate that the Nucleus-Golgi axis aligns with direction of migration leading to efficient cell movement. We show that polarized trafficking is directed toward protrusions with a 20-min delay, and that migration becomes random after disrupting internal cell organization. Eventually, we prove that localized optogenetic Cdc42 activation orients the Nucleus-Golgi axis. Our work suggests that polarized trafficking stabilizes the protrusive activity of the cell, while protrusive activity orients this polarity axis, leading to persistent cell migration. Using a minimal physical model, we show that this feedback is sufficient to recapitulate the quantitative properties of cell migration in the timescale of hours., Competing Interests: KV, AM, AB, WB, KS, MC No competing interests declared, (© 2022, Vaidžiulytė et al.)
- Published
- 2022
- Full Text
- View/download PDF
35. A comprehensive library of fluorescent constructs of SARS-CoV-2 proteins and their initial characterisation in different cell types.
- Author
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Miserey-Lenkei S, Trajkovic K, D'Ambrosio JM, Patel AJ, Čopič A, Mathur P, Schauer K, Goud B, Albanèse V, Gautier R, Subra M, Kovacs D, Barelli H, and Antonny B
- Subjects
- A549 Cells, Cell Line, Green Fluorescent Proteins genetics, Green Fluorescent Proteins metabolism, Host Microbial Interactions physiology, Humans, Luminescent Proteins genetics, Luminescent Proteins metabolism, Microscopy, Fluorescence, Protein Interaction Domains and Motifs, Recombinant Fusion Proteins genetics, Recombinant Fusion Proteins metabolism, SARS-CoV-2 genetics, Saccharomyces cerevisiae genetics, Saccharomyces cerevisiae metabolism, Time-Lapse Imaging, Viral Proteins genetics, Red Fluorescent Protein, COVID-19 virology, Peptide Library, SARS-CoV-2 metabolism, Viral Proteins metabolism
- Abstract
Background Information: Comprehensive libraries of plasmids for SARS-CoV-2 proteins with various tags (e.g., Strep, HA, Turbo) are now available. They enable the identification of numerous potential protein-protein interactions between the SARS-CoV-2 virus and host proteins., Results: We present here a large library of SARS CoV-2 protein constructs fused with green and red fluorescent proteins and their initial characterisation in various human cell lines including lung epithelial cell models (A549, BEAS-2B), as well as in budding yeast. The localisation of a few SARS-CoV-2 proteins matches their proposed interactions with host proteins. These include the localisation of Nsp13 to the centrosome, Orf3a to late endosomes and Orf9b to mitochondria., Conclusions and Significance: This library should facilitate further cellular investigations, notably by imaging techniques., (© 2021 Société Française des Microscopies and Société de Biologie Cellulaire de France. Published by John Wiley & Sons Ltd.)
- Published
- 2021
- Full Text
- View/download PDF
36. The NANOTUMOR consortium - Towards the Tumor Cell Atlas.
- Author
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Colin F, Schauer K, Hamiche A, Martineau P, Borg JP, Bednar J, Bertolin G, Camoin L, Collette Y, Dimitrov S, Fournier I, Hyenne V, Mendoza-Parra MA, Morelli X, Rondé P, Sumara I, Tramier M, Schultz P, and Goetz JG
- Subjects
- Humans, Databases as Topic, Neoplasms pathology
- Abstract
Cancer is a multi-step disease where an initial tumour progresses through critical steps shaping, in most cases, life-threatening secondary foci called metastases. The oncogenic cascade involves genetic, epigenetic, signalling pathways, intracellular trafficking and/or metabolic alterations within cancer cells. In addition, pre-malignant and malignant cells orchestrate complex and dynamic interactions with non-malignant cells and acellular matricial components or secreted factors within the tumour microenvironment that is instrumental in the progression of the disease. As our aptitude to effectively treat cancer mostly depends on our ability to decipher, properly diagnose and impede cancer progression and metastasis formation, full characterisation of molecular complexes and cellular processes at play along the metastasis cascade is crucial. For many years, the scientific community lacked adapted imaging and molecular technologies to accurately dissect, at the highest resolution possible, tumour and stromal cells behaviour within their natural microenvironment. In that context, the NANOTUMOR consortium is a French national multi-disciplinary workforce which aims at a providing a multi-scale characterisation of the oncogenic cascade, from the atomic level to the dynamic organisation of the cell in response to genetic mutations, environmental changes or epigenetic modifications. Ultimately, this program aims at identifying new therapeutic targets using innovative drug design., (© 2021 Société Française des Microscopies and Société de Biologie Cellulaire de France. Published by John Wiley & Sons Ltd.)
- Published
- 2021
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37. Characteristics of the Protein Complexes and Pores Formed by Bacillus cereus Hemolysin BL.
- Author
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Jessberger N, Dietrich R, Schauer K, Schwemmer S, Märtlbauer E, and Benz R
- Subjects
- Animals, Cell Survival, Chlorocebus aethiops, Lipid Bilayers, Porosity, Vero Cells, Bacillus cereus, Bacterial Proteins chemistry, Bacterial Proteins toxicity, Hemolysin Proteins chemistry, Hemolysin Proteins toxicity
- Abstract
Bacillus cereus Hemolysin BL is a tripartite toxin responsible for a diarrheal type of food poisoning. Open questions remain regarding its mode of action, including the extent to which complex formation prior to cell binding contributes to pore-forming activity, how these complexes are composed, and the properties of the pores formed in the target cell membrane. Distinct complexes of up to 600 kDa were found on native gels, whose structure and size were primarily defined by Hbl B. Hbl L1 and L2 were also identified in these complexes using Western blotting and an LC-MS approach. LC-MS also revealed that many other proteins secreted by B. cereus exist in complexes. Further, a decrease of toxic activity at temperatures ≥60 °C was shown, which was unexpectedly restored at higher temperatures. This could be attributed to a release of Hbl B monomers from tight complexation, resulting in enhanced cell binding. In contrast, Hbl L1 was rather susceptible to heat, while heat treatment of Hbl L2 seemed not to be crucial. Furthermore, Hbl-induced pores had a rather small single-channel conductance of around 200 pS and a probable channel diameter of at least 1 nm on planar lipid bilayers. These were highly instable and had a limited lifetime, and were also slightly cation-selective. Altogether, this study provides astonishing new insights into the complex mechanism of Hbl pore formation, as well as the properties of the pores.
- Published
- 2020
- Full Text
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38. Quantifying Spatiotemporal Parameters of Cellular Exocytosis in Micropatterned Cells.
- Author
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Lachuer H, Mathur P, Bleakley K, and Schauer K
- Subjects
- Animals, Cell Membrane metabolism, Cell Shape, Cells, Cultured, Humans, Lysosomes metabolism, SNARE Proteins metabolism, Spatio-Temporal Analysis, Exocytosis
- Abstract
Live imaging of the pHluorin tagged Soluble N-ethylmaleimide-sensitive-factor Attachment protein REceptor (v-SNARE) Vesicle-associated membrane protein 7 (VAMP7) by total internal reflection fluorescence microscopy (TIRFM) is a straightforward way to explore secretion from the lysosomal compartment. Taking advantage of cell culture on micropatterned surfaces to normalize cell shape, a variety of statistical tools were employed to perform a spatial analysis of secretory patterns. Using Ripley's K function and a statistical test based on the nearest neighbor distance (NND), we confirmed that secretion from lysosomes is not a random process but shows significant clustering. Of note, our analysis revealed that exocytosis events are also clustered in nonadhesion areas, indicating that adhesion molecules are not the only structures that can induce secretory hot spots at the plasma membrane. Still, we found that cell adhesion enhances clustering. In addition to precisely defined adhesive and nonadhesive areas, the circular geometry of these micropatterns allows the use of polar coordinates, simplifying analyses. We used Kernel Density Estimation (KDE) and the cumulative distribution function on polar coordinates of exocytosis events to identify enriched areas of exocytosis. In ring-shaped micropattern cells, clustering occurred at the border between the adhesive and nonadhesive areas. Our analysis illustrates how statistical tools can be employed to investigate spatial distributions of diverse biological processes.
- Published
- 2020
- Full Text
- View/download PDF
39. Intracellular organization in cell polarity - placing organelles into the polarity loop.
- Author
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Vaidžiulytė K, Coppey M, and Schauer K
- Subjects
- Animals, Cell Movement genetics, Cell Polarity genetics, Humans, Models, Biological, Signal Transduction genetics, Signal Transduction physiology, Cell Movement physiology, Cell Polarity physiology, Organelles metabolism
- Abstract
Many studies have investigated the processes that support polarity establishment and maintenance in cells. On the one hand, polarity complexes at the cell cortex and their downstream signaling pathways have been assigned as major regulators of polarity. On the other hand, intracellular organelles and their polarized trafficking routes have emerged as important components of polarity. In this Review, we argue that rather than trying to identify the prime 'culprit', now it is time to consider all these players as a collective. We highlight that understanding the intimate coordination between the polarized cell cortex and the intracellular compass that is defined by organelle positioning is essential to capture the concept of polarity. After briefly reviewing how polarity emerges from a dynamic maintenance of cellular asymmetries, we highlight how intracellular organelles and their associated trafficking routes provide diverse feedback for dynamic cell polarity maintenance. We argue that the asymmetric organelle compass is an indispensable element of the polarity network., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2019. Published by The Company of Biologists Ltd.)
- Published
- 2019
- Full Text
- View/download PDF
40. MYO1C stabilizes actin and facilitates the arrival of transport carriers at the Golgi complex.
- Author
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Capmany A, Yoshimura A, Kerdous R, Caorsi V, Lescure A, Del Nery E, Coudrier E, Goud B, and Schauer K
- Subjects
- Cell Line, Cell Movement, Humans, Myosin Type I genetics, Protein Transport, Actin Cytoskeleton metabolism, Actins metabolism, Golgi Apparatus metabolism, Myosin Type I metabolism
- Abstract
In this study, we aimed to identify the myosin motor proteins that control trafficking at the Golgi complex. In addition to the known Golgi-associated myosins MYO6, MYO18A and MYH9 (myosin IIA), we identified MYO1C as a novel player at the Golgi in a human cell line. We demonstrate that depletion of MYO1C induces Golgi complex fragmentation and decompaction. MYO1C accumulates at dynamic structures around the Golgi complex that colocalize with Golgi-associated actin dots. MYO1C depletion leads to loss of cellular F-actin, and Golgi complex decompaction is also observed after inhibition or loss of the actin-related protein 2/3 complex, Arp2/3 (also known as ARPC). We show that the functional consequence of MYO1C depletion is a delay in the arrival of incoming transport carriers, both from the anterograde and retrograde routes. We propose that MYO1C stabilizes actin at the Golgi complex, facilitating the arrival of incoming transport carriers at the Golgi.This article has an associated First Person interview with the first author of the paper., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2019. Published by The Company of Biologists Ltd.)
- Published
- 2019
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41. Draft Genome Sequence and Annotation of Acinetobacter junii MHI21018, Isolated from Bovine Colostrum.
- Author
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Kröger C, Schauer K, Clerkin SR, Märtlbauer E, and Fleming AB
- Abstract
We report here the draft genome sequence of Acinetobacter junii MHI21018, isolated in 2009 from bovine colostrum. The draft genome sequence is composed of 3,267,995 bp, has a GC content of 38.54%, and was assembled into 114 contigs (contig size, >500 bp) with an N
50 value of 72,566 bp.- Published
- 2019
- Full Text
- View/download PDF
42. Analysis of Organelle Positioning Using Patterned Microdevices.
- Author
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Capmany A, Latgé B, and Schauer K
- Subjects
- Cell Adhesion, Cells, Cultured, Humans, Single-Cell Analysis, Imaging, Three-Dimensional instrumentation, Imaging, Three-Dimensional methods, Organelles metabolism
- Abstract
The consequences of alterations in the distribution of intracellular organelles, observed in many diseases, are often not clear. Intracellular organelles alter their morphology and positioning to regulate cell homeostasis and function. We outline how organelle positioning can be studied employing a density-based analysis of 3D images applied to cells that show similar cellular geometries. Quantification is facilitated by the use of single cells seeded on micropatterned substrates that provide cues for controlled cell spreading. This minimal system mimics the reproducible distribution of organelles typically observed in tissues, simplifying image analysis and minimizing the number of cells required for the observation of robust phenotypes. Here we provide guidelines for how the majority of organelles can be efficiently analyzed in cells seeded on adhesive micropatterns. We exemplify how alterations in the positioning of different organelles as a result of the perturbation of the cytoskeleton or associated motor proteins can be efficiently quantified. © 2018 by John Wiley & Sons, Inc., (© 2018 John Wiley & Sons, Inc.)
- Published
- 2019
- Full Text
- View/download PDF
43. A multicomponent toxin from Bacillus cereus incites inflammation and shapes host outcome via the NLRP3 inflammasome.
- Author
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Mathur A, Feng S, Hayward JA, Ngo C, Fox D, Atmosukarto II, Price JD, Schauer K, Märtlbauer E, Robertson AAB, Burgio G, Fox EM, Leppla SH, Kaakoush NO, and Man SM
- Subjects
- Animals, Bacterial Proteins metabolism, Cell Membrane metabolism, Cell Membrane pathology, Cells, Cultured, Culture Media, Conditioned, Enterotoxins chemistry, Enterotoxins metabolism, Female, Hemolysin Proteins metabolism, Immunity, Innate, Macrophages immunology, Macrophages pathology, Macrophages ultrastructure, Male, Mice, Mice, Mutant Strains, NLR Family, Pyrin Domain-Containing 3 Protein antagonists & inhibitors, NLR Family, Pyrin Domain-Containing 3 Protein genetics, Potassium metabolism, Protein Multimerization, Pyroptosis, Survival Analysis, Bacillus cereus immunology, Bacterial Proteins immunology, Enterotoxins immunology, Hemolysin Proteins immunology, Inflammasomes metabolism, Inflammation, NLR Family, Pyrin Domain-Containing 3 Protein metabolism
- Abstract
Host recognition of microbial components is essential in mediating an effective immune response. Cytosolic bacteria must secure entry into the host cytoplasm to facilitate replication and, in doing so, liberate microbial ligands that activate cytosolic innate immune sensors and the inflammasome. Here, we identified a multicomponent enterotoxin, haemolysin BL (HBL), that engages activation of the inflammasome. This toxin is highly conserved among the human pathogen Bacillus cereus. The three subunits of HBL bind to the cell membrane in a linear order, forming a lytic pore and inducing activation of the NLRP3 inflammasome, secretion of interleukin-1β and interleukin-18, and pyroptosis. Mechanistically, the HBL-induced pore results in the efflux of potassium and triggers the activation of the NLRP3 inflammasome. Furthermore, HBL-producing B. cereus induces rapid inflammasome-mediated mortality. Pharmacological inhibition of the NLRP3 inflammasome using MCC950 prevents B. cereus-induced lethality. Overall, our results reveal that cytosolic sensing of a toxin is central to the innate immune recognition of infection. Therapeutic modulation of this pathway enhances host protection against deadly bacterial infections.
- Published
- 2019
- Full Text
- View/download PDF
44. Determining the Intracellular Organization of Organelles.
- Author
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Latgé B and Schauer K
- Subjects
- Cell Culture Techniques instrumentation, Cell Culture Techniques methods, Cell Line, Humans, Imaging, Three-Dimensional instrumentation, Microscopy, Fluorescence instrumentation, Microscopy, Fluorescence methods, Single-Cell Analysis instrumentation, Imaging, Three-Dimensional methods, Lysosomes metabolism, Mitochondria metabolism, Single-Cell Analysis methods
- Abstract
Many studies have found alterations in the positioning and morphology of intracellular organelles under different experimental conditions. Although the precise quantification of these changes is challenging, it is strongly facilitated in single cells that are seeded on micropatterned substrates. Indeed, the controlled microenvironment of the cell leads to a reproducible distribution of organelles, simplifying image analysis and minimizing the number of cells required for robust phenotypes. Here, we outline how alterations in the intracellular organization of lysosomes and mitochondria, as a result of different growth conditions, can be efficiently quantified in cells seeded on adhesive micropatterns.
- Published
- 2019
- Full Text
- View/download PDF
45. Frustrated endocytosis controls contractility-independent mechanotransduction at clathrin-coated structures.
- Author
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Baschieri F, Dayot S, Elkhatib N, Ly N, Capmany A, Schauer K, Betz T, Vignjevic DM, Poincloux R, and Montagnac G
- Subjects
- Cell Line, Cell Proliferation, Clathrin-Coated Vesicles ultrastructure, Humans, MAP Kinase Signaling System, Receptors, Vitronectin metabolism, Clathrin-Coated Vesicles metabolism, Endocytosis, Mechanotransduction, Cellular
- Abstract
It is generally assumed that cells interrogate the mechanical properties of their environment by pushing and pulling on the extracellular matrix (ECM). For instance, acto-myosin-dependent contraction forces exerted at focal adhesions (FAs) allow the cell to actively probe substrate elasticity. Here, we report that a subset of long-lived and flat clathrin-coated structures (CCSs), also termed plaques, are contractility-independent mechanosensitive signaling platforms. We observed that plaques assemble in response to increasing substrate rigidity and that this is independent of FAs, actin and myosin-II activity. We show that plaque assembly depends on αvβ5 integrin, and is a consequence of frustrated endocytosis whereby αvβ5 tightly engaged with the stiff substrate locally stalls CCS dynamics. We also report that plaques serve as platforms for receptor-dependent signaling and are required for increased Erk activation and cell proliferation on stiff environments. We conclude that CCSs are mechanotransduction structures that sense substrate rigidity independently of cell contractility.
- Published
- 2018
- Full Text
- View/download PDF
46. Comparison between Listeria sensu stricto and Listeria sensu lato strains identifies novel determinants involved in infection.
- Author
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Schardt J, Jones G, Müller-Herbst S, Schauer K, D'Orazio SEF, and Fuchs TM
- Subjects
- ATP-Binding Cassette Transporters genetics, Animals, Caco-2 Cells, Cell Line, Tumor, Female, Foodborne Diseases genetics, Foodborne Diseases microbiology, Humans, Listeriosis genetics, Mice, Mice, Inbred BALB C, Virulence genetics, Listeria monocytogenes genetics, Listeriosis microbiology
- Abstract
The human pathogen L. monocytogenes and the animal pathogen L. ivanovii, together with four other species isolated from symptom-free animals, form the "Listeria sensu stricto" clade. The members of the second clade, "Listeria sensu lato", are believed to be solely environmental bacteria without the ability to colonize mammalian hosts. To identify novel determinants that contribute to infection by L. monocytogenes, the causative agent of the foodborne disease listeriosis, we performed a genome comparison of the two clades and found 151 candidate genes that are conserved in the Listeria sensu stricto species. Two factors were investigated further in vitro and in vivo. A mutant lacking an ATP-binding cassette transporter exhibited defective adhesion and invasion of human Caco-2 cells. Using a mouse model of foodborne L. monocytogenes infection, a reduced number of the mutant strain compared to the parental strain was observed in the small intestine and the liver. Another mutant with a defective 1,2-propanediol degradation pathway showed reduced persistence in the stool of infected mice, suggesting a role of 1,2-propanediol as a carbon and energy source of listeriae during infection. These findings reveal the relevance of novel factors for the colonization process of L. monocytogenes.
- Published
- 2017
- Full Text
- View/download PDF
47. Multiplexed Lateral Flow Test for Detection and Differentiation of Cronobacter sakazakii Serotypes O1 and O2.
- Author
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Scharinger EJ, Dietrich R, Wittwer T, Märtlbauer E, and Schauer K
- Abstract
The ubiquitous and opportunistic pathogen Cronobacter sakazakii is responsible for severe meningitis, sepsis, and necrotizing enterocolitis in neonates and infants associated with ingestion of contaminated powdered infant formula (PIF). The current ISO method for isolation and detection of Cronobacter spp. is laborious, time-consuming and expensive. In this study, a multiplexed lateral flow test strip was developed to rapidly detect and simultaneously serotype O1 and O2 C. sakazakii serotypes. The assay is based on two monoclonal antibodies (MAb) that specifically bind to the lipopolysaccharides (LPS) of these pathogens. The test strip provides results very quickly; C. sakazakii could be detected in pure culture within 15 min with a sensitivity of 10
7 CFU/ml. After non-selective enrichment for 18 h as low as one Cronobacter cell per g PIF could be detected. Moreover, the established lateral flow assay (LFA) offers excellent specificity showing no cross-reactivity with other C. sakazakii serotypes, Cronobacter species or Enterobacteriaceae tested. These characteristics, together with several advantages such as speed, simplicity in performance, low analysis cost, and no requirement of specialized skills or sophisticated equipment make the developed multiplexed LFA suitable for reliable detection and serotyping of C. sakazakii serotypes O1 and O2.- Published
- 2017
- Full Text
- View/download PDF
48. Evidence for Complex Formation of the Bacillus cereus Haemolysin BL Components in Solution.
- Author
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Tausch F, Dietrich R, Schauer K, Janowski R, Niessing D, Märtlbauer E, and Jessberger N
- Subjects
- Animals, Antibodies, Monoclonal pharmacology, Antibodies, Neutralizing pharmacology, Bacillus cereus genetics, Bacillus cereus metabolism, Cell Line, Cell Survival drug effects, Chlorocebus aethiops, Escherichia coli genetics, Female, Mice, Inbred BALB C, Solutions, Vero Cells, Bacterial Proteins genetics, Bacterial Proteins immunology, Bacterial Proteins metabolism, Bacterial Proteins toxicity, Hemolysin Proteins genetics, Hemolysin Proteins immunology, Hemolysin Proteins metabolism, Hemolysin Proteins toxicity, Recombinant Proteins genetics, Recombinant Proteins immunology, Recombinant Proteins metabolism, Recombinant Proteins toxicity
- Abstract
Haemolysin BL is an important virulence factor regarding the diarrheal type of food poisoning caused by Bacillus cereus . However, the pathogenic importance of this three-component enterotoxin is difficult to access, as nearly all natural B. cereus culture supernatants additionally contain the highly cytotoxic Nhe, the second three-component toxin involved in the aetiology of B. cereus -induced food-borne diseases. To better address the toxic properties of the Hbl complex, a system for overexpression and purification of functional, cytotoxic, recombinant (r)Hbl components L₂, L₁ and B from E. coli was established and an nheABC deletion mutant was constructed from B. cereus reference strain F837/76. Furthermore, 35 hybridoma cell lines producing monoclonal antibodies (mAbs) against Hbl L₂, L₁ and B were generated. While mAbs 1H9 and 1D8 neutralized Hbl toxicity and thus, represent important tools for future investigations of the mode-of-action of Hbl on the target cell surface, mAb 1D7, in contrast, even enhanced Hbl toxicity by supporting the binding of Hbl B to the cell surface. By using the specific mAbs in Dot blots, indirect and hybrid sandwich enzyme immuno assays (EIAs), complex formation between Hbl L₁ and B, as well as L₁ and L₂ in solution could be shown for the first time. Surface plasmon resonance experiments with the rHbl components confirmed these results with K
D values of 4.7 × 10-7 M and 1.5 × 10-7 M, respectively. These findings together with the newly created tools lay the foundation for the detailed elucidation of the molecular mode-of-action of the highly complex three-component Hbl toxin., Competing Interests: The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.- Published
- 2017
- Full Text
- View/download PDF
49. Palaeogenomes of Eurasian straight-tusked elephants challenge the current view of elephant evolution.
- Author
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Meyer M, Palkopoulou E, Baleka S, Stiller M, Penkman KEH, Alt KW, Ishida Y, Mania D, Mallick S, Meijer T, Meller H, Nagel S, Nickel B, Ostritz S, Rohland N, Schauer K, Schüler T, Roca AL, Reich D, Shapiro B, and Hofreiter M
- Subjects
- Animals, DNA, Mitochondrial genetics, Genome, Mitochondrial, Phylogeny, Sequence Analysis, DNA, Elephants genetics, Evolution, Molecular, Fossils, Genomics
- Abstract
The straight-tusked elephants Palaeoloxodon spp. were widespread across Eurasia during the Pleistocene. Phylogenetic reconstructions using morphological traits have grouped them with Asian elephants ( Elephas maximus ), and many paleontologists place Palaeoloxodon within Elephas . Here, we report the recovery of full mitochondrial genomes from four and partial nuclear genomes from two P. antiquus fossils. These fossils were collected at two sites in Germany, Neumark-Nord and Weimar-Ehringsdorf, and likely date to interglacial periods ~120 and ~244 thousand years ago, respectively. Unexpectedly, nuclear and mitochondrial DNA analyses suggest that P. antiquus was a close relative of extant African forest elephants ( Loxodonta cyclotis ). Species previously referred to Palaeoloxodon are thus most parsimoniously explained as having diverged from the lineage of Loxodonta , indicating that Loxodonta has not been constrained to Africa. Our results demonstrate that the current picture of elephant evolution is in need of substantial revision.
- Published
- 2017
- Full Text
- View/download PDF
50. Regulatory Plasticity of Earthworm wMT-2 Gene Expression.
- Author
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Drechsel V, Schauer K, Šrut M, and Höckner M
- Subjects
- Animals, Cadmium metabolism, DNA Methylation, Oligochaeta physiology, Promoter Regions, Genetic, Stress, Physiological, Gene Expression Regulation, Metallothionein genetics, Oligochaeta genetics
- Abstract
Metallothioneins (MTs) are multifunctional proteins occurring throughout the animal kingdom. While the expression and transcriptional regulation of MTs is well-studied in vertebrates, the mechanism of MT activation is still unknown for most invertebrates. Therefore, we examined wMT-2 gene regulation and expression patterns in Lumbricus rubellus and L. terrestris. Transcription levels, the occupation of DNA binding sites, the expression of putative transcriptional regulators, and promotor DNA methylation were determined. We found that wMT-2 expression does not follow a circadian pattern. However, Cd-induced wMT-2 induction was observed, and was, interestingly, suppressed by physical injury. Moreover, the promotor region that is responsible for the wMT-2 gene regulation was elucidated. ATF, a putative transcriptional regulator, showed increased phosphorylation upon Cd exposure, suggesting that it plays a major role in wMT-2 gene activation. The promotor methylation of wMT-2 , on the other hand, is probably not involved in transcriptional regulation. Elucidating the regulatory mechanism of the earthworm MT gene activation might provide insights into the molecular coordination of the environmental stress response in invertebrates, and might also reveal a link to wound repair and, in a broader sense, to immunity., Competing Interests: The authors declare no conflict of interest.
- Published
- 2017
- Full Text
- View/download PDF
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