TY - JOUR A1 - Gentschev, Ivaylo A1 - Müller, Meike A1 - Adelfinger, Marion A1 - Weibel, Stephanie A1 - Grummt, Friedrich A1 - Zimmermann, Martina A1 - Bitzer, Michael A1 - Heisig, Martin A1 - Zhang, Qian A1 - Yu, Yong A. A1 - Chen, Nanhai G. A1 - Stritzker, Jochen A1 - Lauer, Ulrich M. A1 - Szalay, Aladar A. T1 - Efficient Colonization and Therapy of Human Hepatocellular Carcinoma (HCC) Using the Oncolytic Vaccinia Virus Strain GLV-1h68 JF - PLOS ONE N2 - Virotherapy using oncolytic vaccinia virus strains is one of the most promising new strategies for cancer therapy. In this study, we analyzed for the first time the therapeutic efficacy of the oncolytic vaccinia virus GLV-1h68 in two human hepatocellular carcinoma cell lines HuH7 and PLC/PRF/5 (PLC) in cell culture and in tumor xenograft models. By viral proliferation assays and cell survival tests, we demonstrated that GLV-1h68 efficiently colonized, replicated in, and did lyse these cancer cells in culture. Experiments with HuH7 and PLC xenografts have revealed that a single intravenous injection (i.v.) of mice with GLV-1h68 resulted in a significant reduction of primary tumor sizes compared to uninjected controls. In addition, replication of GLV-1h68 in tumor cells led to strong inflammatory and oncolytic effects resulting in intense infiltration of MHC class II-positive cells like neutrophils, macrophages, B cells and dendritic cells and in up-regulation of 13 pro-inflammatory cytokines. Furthermore, GLV-1h68 infection of PLC tumors inhibited the formation of hemorrhagic structures which occur naturally in PLC tumors. Interestingly, we found a strongly reduced vascular density in infected PLC tumors only, but not in the non-hemorrhagic HuH7 tumor model. These data demonstrate that the GLV-1h68 vaccinia virus may have an enormous potential for treatment of human hepatocellular carcinoma in man. KW - Breast-tumors KW - Nude-mice KW - In-vivo KW - Cancer KW - Inhibitor KW - Tissue KW - Agent KW - COX-2 Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-135319 VL - 6 IS - 7 ER - TY - JOUR A1 - Schierack, Peter A1 - Kleta, Sylvia A1 - Tedin, Karsten A1 - Babila, Julius Tachu A1 - Oswald, Sibylle A1 - Oelschlaeger, Tobias A. A1 - Hiemann, Rico A1 - Paetzold, Susanne A1 - Wieler, Lothar H. T1 - E. coli Nissle 1917 Affects Salmonella Adhesion to Porcine Intestinal Epithelial Cells JF - PLoS ONE N2 - Background: The probiotic Escherichia coli strain Nissle 1917 (EcN) has been shown to interfere in a human in vitro model with the invasion of several bacterial pathogens into epithelial cells, but the underlying molecular mechanisms are not known. Methodology/Principal Findings: In this study, we investigated the inhibitory effects of EcN on Salmonella Typhimurium invasion of porcine intestinal epithelial cells, focusing on EcN effects on the various stages of Salmonella infection including intracellular and extracellular Salmonella growth rates, virulence gene regulation, and adhesion. We show that EcN affects the initial Salmonella invasion steps by modulating Salmonella virulence gene regulation and Salmonella SiiE-mediated adhesion, but not extra-and intracellular Salmonella growth. However, the inhibitory activity of EcN against Salmonella invasion always correlated with EcN adhesion capacities. EcN mutants defective in the expression of F1C fimbriae and flagellae were less adherent and less inhibitory toward Salmonella invasion. Another E. coli strain expressing F1C fimbriae was also adherent to IPEC-J2 cells, and was similarly inhibitory against Salmonella invasion like EcN. Conclusions: We propose that EcN affects Salmonella adhesion through secretory components. This mechanism appears to be common to many E. coli strains, with strong adherence being a prerequisite for an effective reduction of SiiE-mediated Salmonella adhesion. KW - Nonpathogenic Escherichia-coli KW - Enterica serovar typhimurium KW - Strain nissle-1917 KW - In-vitro KW - Invasion genes KW - Diarrhea KW - Growth KW - Expression KW - Infection KW - PPGPP Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-135298 VL - 6 IS - 2 ER - TY - JOUR A1 - Hertlein, Tobias A1 - Sturm, Volker A1 - Kircher, Stefan A1 - Basse-Lüsebrink, Thomas A1 - Haddad, Daniel A1 - Ohlsen, Knut A1 - Jakob, Peter T1 - Visualization of Abscess Formation in a Murine Thigh Infection Model of \(Staphylococcus\) \(aureus\) by (19)F-Magnetic Resonance Imaging (MRI) JF - PLoS ONE N2 - Background: During the last years, (19)F-MRI and perfluorocarbon nanoemulsion (PFC) emerged as a powerful contrast agent methodology to track cells and to visualize inflammation. We applied this new modality to visualize deep tissue abscesses during acute and chronic phase of inflammation caused by Staphylococcus aureus infection. Methodology and Principal Findings: In this study, a murine thigh infection model was used to induce abscess formation and PFC or CLIO (cross linked ironoxides) was administered during acute or chronic phase of inflammation. 24 h after inoculation, the contrast agent accumulation was imaged at the site of infection by MRI. Measurements revealed a strong accumulation of PFC at the abscess rim at acute and chronic phase of infection. The pattern was similar to CLIO accumulation at chronic phase and formed a hollow sphere around the edema area. Histology revealed strong influx of neutrophils at the site of infection and to a smaller extend macrophages during acute phase and strong influx of macrophages at chronic phase of inflammation. Conclusion and Significance: We introduce (19)F-MRI in combination with PFC nanoemulsions as a new platform to visualize abscess formation in a murine thigh infection model of S. aureus. The possibility to track immune cells in vivo by this modality offers new opportunities to investigate host immune response, the efficacy of antibacterial therapies and the influence of virulence factors for pathogenesis. KW - Soft-tissue infection KW - In-vivo KW - Iron-oxide KW - F-19 MRI KW - Inflammation KW - Particles KW - Tracking KW - Lesions KW - Images KW - Rats Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-142846 VL - 6 IS - 3 ER - TY - JOUR A1 - Cull, Benjamin A1 - Lima Prado Godinho, Joseane A1 - Fernandes Rodrigues, Juliany Cola A1 - Frank, Benjamin A1 - Schurigt, Uta A1 - Williams, Roderick AM A1 - Coombs, Graham H A1 - Mottram, Jeremy C T1 - Glycosome turnover in Leishmania major is mediated by autophagy JF - Autophagy N2 - Autophagy is a central process behind the cellular remodeling that occurs during differentiation of Leishmania, yet the cargo of the protozoan parasite's autophagosome is unknown. We have identified glycosomes, peroxisome-like organelles that uniquely compartmentalize glycolytic and other metabolic enzymes in Leishmania and other kinetoplastid parasitic protozoa, as autophagosome cargo. It has been proposed that the number of glycosomes and their content change during the Leishmania life cycle as a key adaptation to the different environments encountered. Quantification of RFP-SQL-labeled glycosomes showed that promastigotes of L. major possess ~20 glycosomes per cell, whereas amastigotes contain ~10. Glycosome numbers were significantly greater in promastigotes and amastigotes of autophagy-defective L. major Δatg5 mutants, implicating autophagy in glycosome homeostasis and providing a partial explanation for the previously observed growth and virulence defects of these mutants. Use of GFP-ATG8 to label autophagosomes showed glycosomes to be cargo in ~15% of them; glycosome-containing autophagosomes were trafficked to the lysosome for degradation. The number of autophagosomes increased 10-fold during differentiation, yet the percentage of glycosome-containing autophagosomes remained constant. This indicates that increased turnover of glycosomes was due to an overall increase in autophagy, rather than an upregulation of autophagosomes containing this cargo. Mitophagy of the single mitochondrion was not observed in L. major during normal growth or differentiation; however, mitochondrial remnants resulting from stress-induced fragmentation colocalized with autophagosomes and lysosomes, indicating that autophagy is used to recycle these damaged organelles. These data show that autophagy in Leishmania has a central role not only in maintaining cellular homeostasis and recycling damaged organelles but crucially in the adaptation to environmental change through the turnover of glycosomes. KW - ATG8 KW - Leishmania KW - TEM KW - glycosome KW - protozoan parasite KW - ATG KW - autophagy-related KW - GFP KW - green fluorescent protein KW - MVT KW - multivesicular tubule KW - RFP KW - red fluorescent protein KW - transmission electron microscopy KW - adaptation KW - autophagy KW - mC KW - mCherry KW - fluorescent protein Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-150277 VL - 10 IS - 12 ER - TY - JOUR A1 - Bergmiller, Tobias A1 - Pena-Miller, Rafael A1 - Boehm, Alexander A1 - Ackermann, Martin T1 - Single-cell time-lapse analysis of depletion of the universally conserved essential protein YgjD JF - BMC Microbiology N2 - Background: The essential Escherichia coli gene ygjD belongs to a universally conserved group of genes whose function has been the focus of a number of recent studies. Here, we put ygjD under control of an inducible promoter, and used time-lapse microscopy and single cell analysis to investigate the phenotypic consequences of the depletion of YgjD protein from growing cells. Results: We show that loss of YgjD leads to a marked decrease in cell size and termination of cell division. The transition towards smaller size occurs in a controlled manner: cell elongation and cell division remain coupled, but cell size at division decreases. We also find evidence that depletion of YgjD leads to the synthesis of the intracellular signaling molecule (p) ppGpp, inducing a cellular reaction resembling the stringent response. Concomitant deletion of the relA and spoT genes - leading to a strain that is uncapable of synthesizing (p) ppGpp abrogates the decrease in cell size, but does not prevent termination of cell division upon YgjD depletion. Conclusions: Depletion of YgjD protein from growing cells leads to a decrease in cell size that is contingent on (p) ppGpp, and to a termination of cell division. The combination of single-cell time-lapse microscopy and statistical analysis can give detailed insights into the phenotypic consequences of the loss of essential genes, and can thus serve as a new tool to study the function of essential genes. KW - Transfer-RNA modification KW - Escherichia-coli K-12 KW - Gene KW - Division KW - Expression KW - Inactivation KW - Maintenance KW - Growth KW - Level KW - Ftsz Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-142324 VL - 11 IS - 118 ER - TY - JOUR A1 - Chen, Nanhai G. A1 - Yu, Yong A. A1 - Zhang, Qian A1 - Szalay, Aladar A. T1 - Replication efficiency of oncolytic vaccinia virus in cell cultures prognosticates the virulence and antitumor efficacy in mice JF - Journal of Translational Medicine N2 - Background: We have shown that insertion of the three vaccinia virus (VACV) promoter-driven foreign gene expression cassettes encoding Renilla luciferase-Aequorea GFP fusion protein, beta-galactosidase, and beta-glucuronidase into the F14.5L, J2R, and A56R loci of the VACV LIVP genome, respectively, results in a highly attenuated mutant strain GLV 1h68. This strain shows tumor specific replication and is capable of eradicating tumors with little or no virulence in mice. This study aimed to distinguish the contribution of added VACV promoter-driven transcriptional units as inserts from the effects of insertional inactivation of three viral genes, and to determine the correlation between replication efficiency of oncolytic vaccinia virus in cell cultures and the virulence and antitumor efficacy in mice Methods: A series of recombinant VACV strains was generated by replacing one, two, or all three of the expression cassettes in GLV 1h68 with short non coding DNA sequences. The replication efficiency and tumor cell killing capacity of these newly generated VACV strains were compared with those of the parent virus GLV-1h68 in cell cultures. The virus replication efficiency in tumors and antitumor efficacy as well as the virulence were evaluated in nu/nu (nude) mice bearing human breast tumor xenografts. Results: we found that virus replication efficiency increased with removal of each of the expression cassettes. The increase in virus replication efficiency was proportionate to the strength of removed VACV promoters linked to foreign genes. The replication efficiency of the new VACV strains paralleled their cytotoxicity in cell cultures. The increased replication efficiency in tumor xenografts resulted in enhanced antitumor efficacy in nude mice. Similarly, the enhanced virus replication efficiency was indicative of increased virulence in nude mice. Conclusions: These data demonstrated that insertion of VACV promoter-driven transcriptional units into the viral genome for the purpose of insertional mutagenesis did modulate the efficiency of virus replication together with antitumor efficacy as well as virulence. Replication efficiency of oncolytic VACV in cell cultures can predict the virulence and therapeutic efficacy in nude mice. These findings may be essential for rational design of safe and potent VACV strains for vaccination and virotherapy of cancer in humans and animals. KW - Recombinant vaccinia KW - Nude-mice KW - Cancer KW - GLV-1H68 KW - Therapy KW - Agent KW - Regression KW - Carcinoma KW - Deletion KW - Protein KW - modulation of virus replication KW - GI-101A tumor xenografts KW - oncolytic virotherapy Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-142268 VL - 9 IS - 164 ER - TY - THES A1 - Lerch, Maike Franziska T1 - Characterisation of a novel non-coding RNA and its involvement in polysaccharide intercellular adhesin (PIA)-mediated biofilm formation of \(Staphylococcus\) \(epidermidis\) T1 - Charakterisierung einer neuen nicht-kodierenden RNA und deren Beteiligung an der PIA-vermittelten Biofilmbildung von \(Staphylococcus\) \(epidermidis\) N2 - Coagulase-negative staphylococci, particularly Staphylococcus epidermidis, have been recognised as an important cause of health care-associated infections due to catheterisation, and livestock-associated infections. The colonisation of indwelling medical devices is achieved by the formation of biofilms, which are large cell-clusters surrounded by an extracellular matrix. This extracellular matrix consists mainly of PIA (polysaccharide intercellular adhesin), which is encoded by the icaADBC-operon. The importance of icaADBC in clinical strains provoking severe infections initiated numerous investigations of this operon and its regulation within the last two decades. The discovery of a long transcript being located next to icaADBC, downstream of the regulator gene icaR, led to the hypothesis of a possible involvement of this transcript in the regulation of biofilm formation (Eckart, 2006). Goal of this work was to characterise this transcript, named ncRNA IcaZ, in molecular detail and to uncover its functional role in S. epidermidis. The ~400 nt long IcaZ is specific for ica-positive S. epidermidis and is transcribed in early- and mid-exponential growth phase as primary transcript. The promotor sequence and the first nucleotides of icaZ overlap with the 3' UTR of the preceding icaR gene, whereas the terminator sequence is shared by tRNAThr-4, being located convergently to icaZ. Deletion of icaZ resulted in a macroscopic biofilm-negative phenotype with highly diminished PIA-biofilm. Biofilm composition was analysed in vitro by classical crystal violet assays and in vivo by confocal laser scanning microscopy under flow conditions to display biofilm formation in real-time. The mutant showed clear defects in initial adherence and decreased cell-cell adherence, and was therefore not able to form a proper biofilm under flow in contrast to the wildtype. Restoration of PIA upon providing icaZ complementation from plasmids revealed inconsistent results in the various mutant backgrounds. To uncover the functional role of IcaZ, transcriptomic and proteomic analysis was carried out, providing some hints on candidate targets, but the varying biofilm phenotypes of wildtype and icaZ mutants made it difficult to identify direct IcaZ mRNA targets. Pulse expression of icaZ was then used as direct fishing method and computational target predictions were executed with candidate mRNAs from aforesaid approaches. The combined data of these analyses suggested an involvement of icaR in IcaZ-mediated biofilm control. Therefore, RNA binding assays were established for IcaZ and icaR mRNA. A positive gel shift was maintained with icaR 3' UTR and with 5'/3' icaR mRNA fusion product, whereas no gel shift was obtained with icaA mRNA. From these assays, it was assumed that IcaZ regulates icaR mRNA expression in S. epidermidis. S. aureus instead lacks ncRNA IcaZ and its icaR mRNA was shown to undergo autoregulation under so far unknown circumstances by intra- or intermolecular binding of 5' UTR and 3' UTR (Ruiz de los Mozos et al., 2013). Here, the Shine-Dalgarno sequence is blocked through 5'/3' UTR base pairing and RNase III, an endoribonuclease, degrades icaR mRNA, leading to translational blockade. In this work, icaR mRNA autoregulation was therefore analysed experimentally in S. epidermidis and results showed that this specific autoregulation does not take place in this organism. An involvement of RNase III in the degradation process could not be verified here. GFP-reporter plasmids were generated to visualise the interaction, but have to be improved for further investigations. In conclusion, IcaZ was found to interact with icaR mRNA, thereby conceivably interfering with translation initiation of repressor IcaR, and thus to promote PIA synthesis and biofilm formation. In addition, the environmental factor ethanol was found to induce icaZ expression, while only weak or no effects were obtained with NaCl and glucose. Ethanol, actually is an ingredient of disinfectants in hospital settings and known as efficient effector for biofilm induction. As biofilm formation on medical devices is a critical factor hampering treatment of S. epidermidis infections in clinical care, the results of this thesis do not only contribute to better understanding of the complex network of biofilm regulation in staphylococci, but may also have practical relevance in the future. N2 - Koagulase-negative Staphylokokken besiedeln die menschliche und tierische Haut, sowie die Schleimhäute. Durch Läsionen oder das Einbringen von medizinischen Instrumenten wie Kathetern gelangen sie in tiefere Hautschichten oder die Blutbahn und können dort schwerwiegende Infektionen auslösen, vor Allem bei Risikopersonen. Besonders Staphylococcus epidermidis hat sich als Verursacher von nosokomialen Infektionen, aber auch als Pathogen in der Tierhaltung etabliert. Die Bakterien bilden bei der Besiedlung sogenannte Biofilme aus (d.h. eine Akkumulation der Keime, die von einer extrazellulären Matrix umgeben sind). Diese Matrix besteht neben Proteinen und eDNA hauptsächlich aus einem Polysaccharid, dem interzellulären Adhäsin PIA (engl.: polysaccharide intercellular adhesin). Dieses wird durch die Ica-Proteine synthetisiert, die im icaADBC-Operon (engl.: intercellular adhesin operon) kodiert sind. Das Operon hat große Bedeutung in klinischen Stämmen und wurde daher innerhalb der letzten beiden Jahrzehnte eingehend untersucht, auch im Hinblick auf seine Regulation. In der unmittelbaren Umgebung des icaADBC-Operons, stromabwärts des icaR Gens, das für den Repressor des ica-Operons (IcaR) kodiert, wurde ein großes Transkript identifiziert, von dem vermutet wird, dass es möglicherweise an der Regulation der Biofilmbildung beteiligt ist (Eckart, 2006). Ziel dieser Arbeit war es, dieses Transkript zu charakterisieren und seine Funktion in S. epidermidis aufzudecken. Die nicht-kodierende RNA, genannt IcaZ, hat eine Länge von ~400 nt und ist spezifisch für ica-positive S. epidermidis. Sie wird in der frühen bis mittleren exponentiellen Phase temperaturabhängig exprimiert. Stromaufwärts überlappt das icaZ-Gen und dessen Promotor mit der 3' UTR vom icaR-Gen. Stromabwärts wird das icaZ-Gen vom einem Transkriptionsterminator begrenzt, der auch für das tRNAThr-4-Gen benutzt wird, das auf dem gegenüberliegenden Strang in Richtung des icaZ-Gens lokalisiert ist. Die Deletion der RNA führte zu einem makroskopisch sichtbaren Biofilm-negativen Phänotyp mit deutlich verminderter PIA Bildung. Die Biofilmzusammensetzung wurde in vitro mittels eines klassischen Kristallviolett-Assays gemessen und die Biofilmbildung in vivo in Echtzeit mittels konfokaler Mikroskopie (CLSM) betrachtet. Dabei wurde mit einer peristaltischen Pumpe ein Mediumfluss appliziert. Die Mutante zeigte klare Defekte in der initialen Adhärenz und in der Zell-Zell Adhäsion. Sie bildete im Gegensatz zum Wildtyp keinen strukturierten Biofilm aus. Zur Komplementierung des Biofilms wurde die IcaZ von einem Plasmid exprimiert und die Biofilmzusammensetzung nach 18-20 Stunden Wachstum gemessen. Die Ergebnisse dieser Untersuchungen in den verschiedenen Mutanten waren nicht eindeutig. Um die Funktion von IcaZ aufzudecken, wurden Transkriptom- und Proteomvergleiche zwischen Wildtyp und Mutante gemacht. Diese lieferten einige Hinweise, aber da der metabolische Unterschied eines Biofilmbildners zu einem Nicht-Biofilmbildner zu groß war, wurde eine direktere Methode angewandt, die induzierte Expression (Pulsexpression). Zudem wurden potentielle Interaktionspartner der IcaZ mittels computer-basierter Bindungsvorhersagen analysiert. Die icaR mRNA kristallisierte sich dabei als Target heraus und die Interaktion zwischen IcaZ und icaR mRNA wurde mit Gelshift-Assays (EMSA) untersucht. Eine Bandenverschiebung wurde mit icaR 3' UTR und mit dem icaR-5'-3' UTR-Fusionsprodukt detektiert, wohingegen keine Interaktion zwischen IcaZ und icaA mRNA stattfand. Aufgrund dieser Assays wurde vermutet, dass IcaZ die Translation von icaR in S. epidermidis reguliert. In S. aureus fehlt die nicht-kodierende RNA IcaZ und für icaR mRNA wurde eine Autoregulation gezeigt, bei der die icaR 5' UTR mit der icaR 3' UTR intramolekular oder intermolekular durch Basenpaarung interagiert, wodurch die Shine-Dalgarno Sequenz blockiert wird und es aufgrund dessen zu einer Hemmung der Translation kommt. Die Umweltfaktoren, die dazu führen sind bisher unbekannt. Der Komplex wird durch eine Endoribonuklease, RNase III, abgebaut (Ruiz de los Mozos et al., 2013). In S. epidermidis wurde eine solche Interaktion theoretisch ausgeschlossen. Experimentelle Analysen dieser Arbeit haben gezeigt, dass diese Autoregulation in S. epidermidis nicht stattfinden kann und es wird angenommen, dass IcaZ diese Regulation übernimmt. Um die Interaktion zu visualisieren wurden GFP-Reporter Plasmide generiert, die aber für weitere Experimente noch zu verbessern sind. Zusammenfassend lässt sich sagen, dass IcaZ mit der icaR mRNA interagiert, was höchstwahrscheinlich zu einer Hemmung der Translation des Repressors IcaR führt und damit letztlich PIA-Synthese und Biofilmbildung positiv reguliert. Zusätzlich wurde gefunden, dass Ethanol die Expression der IcaZ-RNA induziert, während NaCl nur schwache Effekte zeigte und Glucose keinen Einfluss auf die Expression von icaZ hatte. Ethanol ist ein Bestandteil von Desinfektionsmitteln, die in Krankenhäusern verwendet werden und ist bekannt dafür Biofilmbildung auszulösen. Da die Bildung von Biofilmen auf medizinischen Geräten kritisch ist und diese die Behandlung von S. epidermidis Infektionen erschweren, tragen die Ergebnisse dieser Arbeit nicht nur zu einem besseren Verständnis des komplexen Netzwerks der Biofilmregulation bei, sondern haben möglicherweise auch praktischen Nutzen in der Zukunft. KW - Biofilm KW - Staphylococcus epidermidis KW - Non-coding RNA KW - Hospitalismus KW - icaADBC KW - Nosocomial Infections KW - Polysaccharide intercellular adhesin (PIA) KW - Biofilm formation KW - non-coding RNA KW - ncRNA KW - Nosokomiale Infektionen Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-155777 ER - TY - JOUR A1 - Boes, Alexander A1 - Spiegel, Holger A1 - Voepel, Nadja A1 - Edgue, Gueven A1 - Beiss, Veronique A1 - Kapelski, Stephanie A1 - Fendel, Rolf A1 - Scheuermayer, Matthias A1 - Pradel, Gabriele A1 - Bolscher, Judith M. A1 - Behet, Marije C. A1 - Dechering, Koen J. A1 - Hermsen, Cornelus C. A1 - Sauerwein, Robert W. A1 - Schillberg, Stefan A1 - Reimann, Andreas A1 - Fischer, Rainer T1 - Analysis of a multi-component multi-stage malaria vaccine candidate—tackling the cocktail challenge JF - PLoS ONE N2 - Combining key antigens from the different stages of the P. falciparum life cycle in the context of a multi-stage-specific cocktail offers a promising approach towards the development of a malaria vaccine ideally capable of preventing initial infection, the clinical manifestation as well as the transmission of the disease. To investigate the potential of such an approach we combined proteins and domains (11 in total) from the pre-erythrocytic, blood and sexual stages of P. falciparum into a cocktail of four different components recombinantly produced in plants. After immunization of rabbits we determined the domain-specific antibody titers as well as component-specific antibody concentrations and correlated them with stage specific in vitro efficacy. Using purified rabbit immune IgG we observed strong inhibition in functional in vitro assays addressing the pre-erythrocytic (up to 80%), blood (up to 90%) and sexual parasite stages (100%). Based on the component-specific antibody concentrations we calculated the IC50 values for the pre-erythrocytic stage (17–25 μg/ml), the blood stage (40–60 μg/ml) and the sexual stage (1.75 μg/ml). While the results underline the feasibility of a multi-stage vaccine cocktail, the analysis of component-specific efficacy indicates significant differences in IC50 requirements for stage-specific antibody concentrations providing valuable insights into this complex scenario and will thereby improve future approaches towards malaria vaccine cocktail development regarding the selection of suitable antigens and the ratios of components, to fine tune overall and stage-specific efficacy. KW - malaria KW - vaccines KW - antibodies KW - P. falciparum Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-173092 VL - 10 IS - 7 ER - TY - JOUR A1 - Hill, Philip J. A1 - Stritzker, Jochen A1 - Scadeng, Miriam A1 - Geissinger, Ulrike A1 - Haddad, Daniel A1 - Basse-Lüsebrink, Thomas C. A1 - Gbureck, Uwe A1 - Jakob, Peter A1 - Szalay, Aladar A. T1 - Magnetic Resonance Imaging of Tumors Colonized with Bacterial Ferritin-Expressing \(Escherichia\) \(coli\) JF - PLoS ONE N2 - Background: Recent studies have shown that human ferritin can be used as a reporter of gene expression for magnetic resonance imaging (MRI). Bacteria also encode three classes of ferritin-type molecules with iron accumulation properties. Methods and Findings: Here, we investigated whether these bacterial ferritins can also be used as MRI reporter genes and which of the bacterial ferritins is the most suitable reporter. Bacterial ferritins were overexpressed in probiotic E. coli Nissle 1917. Cultures of these bacteria were analyzed and those generating highest MRI contrast were further investigated in tumor bearing mice. Among members of three classes of bacterial ferritin tested, bacterioferritin showed the most promise as a reporter gene. Although all three proteins accumulated similar amounts of iron when overexpressed individually, bacterioferritin showed the highest contrast change. By site-directed mutagenesis we also show that the heme iron, a unique part of the bacterioferritin molecule, is not critical for MRI contrast change. Tumor-specific induction of bacterioferritin-expression in colonized tumors resulted in contrast changes within the bacteria-colonized tumors. Conclusions: Our data suggest that colonization and gene expression by live vectors expressing bacterioferritin can be monitored by MRI due to contrast changes. KW - Blood-brain barrier KW - Gene-expression KW - Salmonella-typhimurium KW - Sugar-transport KW - Breast-tumors KW - MRI reporter KW - Iron-uptake KW - Proteins KW - Therapy KW - Mice Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-140920 VL - 6 IS - 10 ER - TY - JOUR A1 - Firdessa, Rebuma A1 - Good, Liam A1 - Amstalden, Maria Cecilia A1 - Chindera, Kantaraja A1 - Kamaruzzaman, Nor Fadhilah A1 - Schultheis, Martina A1 - Röger, Bianca A1 - Hecht, Nina A1 - Oelschlaeger, Tobias A. A1 - Meinel, Lorenz A1 - Lühmann, Tessa A1 - Moll, Heidrun T1 - Pathogen- and host-directed antileishmanial effects mediated by polyhexanide (PHMB) JF - PLoS Neglected Tropical Diseases N2 - Background Cutaneous leishmaniasis (CL) is a neglected tropical disease caused by protozoan parasites of the genus Leishmania. CL causes enormous suffering in many countries worldwide. There is no licensed vaccine against CL, and the chemotherapy options show limited efficacy and high toxicity. Localization of the parasites inside host cells is a barrier to most standard chemo- and immune-based interventions. Hence, novel drugs, which are safe, effective and readily accessible to third-world countries and/or drug delivery technologies for effective CL treatments are desperately needed. Methodology/Principal Findings Here we evaluated the antileishmanial properties and delivery potential of polyhexamethylene biguanide (PHMB; polyhexanide), a widely used antimicrobial and wound antiseptic, in the Leishmania model. PHMB showed an inherent antileishmanial activity at submicromolar concentrations. Our data revealed that PHMB kills Leishmania major (L. major) via a dual mechanism involving disruption of membrane integrity and selective chromosome condensation and damage. PHMB's DNA binding and host cell entry properties were further exploited to improve the delivery and immunomodulatory activities of unmethylated cytosine-phosphate-guanine oligodeoxynucleotides (CpG ODN). PHMB spontaneously bound CpG ODN, forming stable nanopolyplexes that enhanced uptake of CpG ODN, potentiated antimicrobial killing and reduced host cell toxicity of PHMB. Conclusions Given its low cost and long history of safe topical use, PHMB holds promise as a drug for CL therapy and delivery vehicle for nucleic acid immunomodulators. KW - resistance KW - activation KW - dendritic cells KW - Cutaneous leishmaniasis KW - topical treatment KW - biocide polyhexamethylene biguanide KW - experimental visceral leishmaniasis KW - drug-delivery systems KW - therapy KW - paromomycin Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-148162 VL - 9 IS - 10 ER - TY - JOUR A1 - Belair, Cédric A1 - Baud, Jessica A1 - Chabas, Sandrine A1 - Sharma, Cynthia M A1 - Vogel, Jörg A1 - Staedel, Cathy A1 - Darfeuille, Fabien T1 - Helicobacter pylori interferes with an embryonic stem cell micro RNA cluster to block cell cycle progression JF - Silence : a Journal of RNA regulation N2 - Background MicroRNAs, post-transcriptional regulators of eukaryotic gene expression, are implicated in host defense against pathogens. Viruses and bacteria have evolved strategies that suppress microRNA functions, resulting in a sustainable infection. In this work we report that Helicobacter pylori, a human stomach-colonizing bacterium responsible for severe gastric inflammatory diseases and gastric cancers, downregulates an embryonic stem cell microRNA cluster in proliferating gastric epithelial cells to achieve cell cycle arrest. Results Using a deep sequencing approach in the AGS cell line, a widely used cell culture model to recapitulate early events of H. pylori infection of gastric mucosa, we reveal that hsa-miR-372 is the most abundant microRNA expressed in this cell line, where, together with hsa-miR-373, it promotes cell proliferation by silencing large tumor suppressor homolog 2 (LATS2) gene expression. Shortly after H. pylori infection, miR-372 and miR-373 synthesis is highly inhibited, leading to the post-transcriptional release of LATS2 expression and thus, to a cell cycle arrest at the G1/S transition. This downregulation of a specific cell-cycle-regulating microRNA is dependent on the translocation of the bacterial effector CagA into the host cells, a mechanism highly associated with the development of severe atrophic gastritis and intestinal-type gastric carcinoma. Conclusions These data constitute a novel example of host-pathogen interplay involving microRNAs, and unveil the couple LATS2/miR-372 and miR-373 as an unexpected mechanism in infection-induced cell cycle arrest in proliferating gastric cells, which may be relevant in inhibition of gastric epithelium renewal, a major host defense mechanism against bacterial infections. KW - MicroRNAs KW - cell cycle KW - Helicobacter pylori KW - gastric cancer Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-140438 VL - 2 IS - 7 ER - TY - JOUR A1 - Okoro, Chinyere K. A1 - Barquist, Lars A1 - Connor, Thomas R. A1 - Harris, Simon R. A1 - Clare, Simon A1 - Stevens, Mark P. A1 - Arends, Mark J. A1 - Hale, Christine A1 - Kane, Leanne A1 - Pickard, Derek J. A1 - Hill, Jennifer A1 - Harcourt, Katherine A1 - Parkhill, Julian A1 - Dougan, Gordon A1 - Kingsley, Robert A. T1 - Signatures of adaptation in human invasive Salmonella Typhimurium ST313 populations from sub-Saharan Africa JF - PLoS Neglected Tropical Diseases N2 - Two lineages of Salmonella enterica serovar Typhimurium (S. Typhimurium) of multi-locus sequence type ST313 have been linked with the emergence of invasive Salmonella disease across sub-Saharan Africa. The expansion of these lineages has a temporal association with the HIV pandemic and antibiotic usage. We analysed the whole genome sequence of 129 ST313 isolates representative of the two lineages and found evidence of lineage-specific genome degradation, with some similarities to that observed in S. Typhi. Individual ST313 S. Typhimurium isolates exhibit a distinct metabolic signature and modified enteropathogenesis in both a murine and cattle model of colitis, compared to S. Typhimurium outside of the ST313 lineages. These data define phenotypes that distinguish ST313 isolates from other S. Typhimurium and may represent adaptation to a distinct pathogenesis and lifestyle linked to an-immuno-compromised human population. KW - genome sequence KW - infection KW - pathogenicity KW - children KW - disease KW - adults KW - identification KW - Escherichia coli KW - virulence Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-143779 VL - 9 IS - 3 ER - TY - JOUR A1 - Dembek, Marcin A1 - Barquist, Lars A1 - Boinett, Christine J. A1 - Cain, Amy K. A1 - Mayho, Matthew A1 - Lawley, Trevor D. A1 - Fairweather, Neil F. A1 - Fagan, Robert P. T1 - High-throughput analysis of gene essentiality and sporulation in Clostridium difficile JF - mBio N2 - Clostridium difficile is the most common cause of antibiotic-associated intestinal infections and a significant cause of morbidity and mortality. Infection with C. difficile requires disruption of the intestinal microbiota, most commonly by antibiotic usage. Therapeutic intervention largely relies on a small number of broad-spectrum antibiotics, which further exacerbate intestinal dysbiosis and leave the patient acutely sensitive to reinfection. Development of novel targeted therapeutic interventions will require a detailed knowledge of essential cellular processes, which represent attractive targets, and species-specific processes, such as bacterial sporulation. Our knowledge of the genetic basis of C. difficile infection has been hampered by a lack of genetic tools, although recent developments have made some headway in addressing this limitation. Here we describe the development of a method for rapidly generating large numbers of transposon mutants in clinically important strains of C. difficile. We validated our transposon mutagenesis approach in a model strain of C. difficile and then generated a comprehensive transposon library in the highly virulent epidemic strain R20291 (027/BI/NAP1) containing more than 70,000 unique mutants. Using transposon-directed insertion site sequencing (TraDIS), we have identified a core set of 404 essential genes, required for growth in vitro. We then applied this technique to the process of sporulation, an absolute requirement for C. difficile transmission and pathogenesis, identifying 798 genes that are likely to impact spore production. The data generated in this study will form a valuable resource for the community and inform future research on this important human pathogen. KW - Bacillus subtilis KW - expression KW - spores KW - toxin KW - transcription KW - germination KW - transposition KW - metabolism KW - infection KW - in vitro Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-143745 VL - 6 IS - 2 ER - TY - JOUR A1 - Berg, Stefan A1 - Schelling, Esther A1 - Hailu, Elena A1 - Firdessa, Rebuma A1 - Gumi, Balako A1 - Erenso, Girume A1 - Gadisa, Endalamaw A1 - Mengistu, Araya A1 - Habtamu, Meseret A1 - Hussein, Jemal A1 - Kiros, Teklu A1 - Bekele, Shiferaw A1 - Mekonnen, Wondale A1 - Derese, Yohannes A1 - Zinsstag, Jakob A1 - Ameni, Gobena A1 - Gagneux, Sebastien A1 - Robertson, Brian D A1 - Tschopp, Rea A1 - Hewinson, Glyn A1 - Yamuah, Lawrence A1 - Gordon, Stephen V A1 - Aseffa, Abraham T1 - Investigation of the high rates of extrapulmonary tuberculosis in Ethiopia reveals no single driving factor and minimal evidence for zoonotic transmission of Mycobacterium bovis infection JF - BMC Infectious Diseases N2 - Background: Ethiopia, a high tuberculosis (TB) burden country, reports one of the highest incidence rates of extra-pulmonary TB dominated by cervical lymphadenitis (TBLN). Infection with Mycobacterium bovis has previously been excluded as the main reason for the high rate of extra-pulmonary TB in Ethiopia. Methods: Here we examined demographic and clinical characteristics of 953 pulmonary (PTB) and 1198 TBLN patients visiting 11 health facilities in distinct geographic areas of Ethiopia. Clinical characteristics were also correlated with genotypes of the causative agent, Mycobacterium tuberculosis. Results: No major patient or bacterial strain factor could be identified as being responsible for the high rate of TBLN, and there was no association with HIV infection. However, analysis of the demographic data of involved patients showed that having regular and direct contact with live animals was more associated with TBLN than with PTB, although no M. bovis was isolated from patients with TBLN. Among PTB patients, those infected with Lineage 4 reported "contact with other TB patient" more often than patients infected with Lineage 3 did (OR = 1.6, CI 95% 1.0-2.7; p = 0.064). High fever, in contrast to low and moderate fever, was significantly associated with Lineage 4 (OR = 2.3; p = 0.024). On the other hand, TBLN cases infected with Lineage 4 tended to get milder symptoms overall for the constitutional symptoms than those infected with Lineage 3. Conclusions: The study suggests a complex role for multiple interacting factors in the epidemiology of extra-pulmonary TB in Ethiopia, including factors that can only be derived from population-based studies, which may prove to be significant for TB control in Ethiopia. KW - zoonotic KW - Mycobacterium KW - Ethiopia KW - tuberculosis KW - Bovis KW - pulmonary KW - extrapulmonary KW - lymphadenitis Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-143935 VL - 15 IS - 112 ER - TY - JOUR A1 - Böhm, Lena A1 - Torsin, Sanda A1 - Tint, Su Hlaing A1 - Eckstein, Marie Therese A1 - Ludwig, Tobias A1 - Pérez, J. Christian T1 - The yeast form of the fungus Candida albicans promotes persistence in the gut of gnotobiotic mice JF - PLoS Pathogens N2 - Many microorganisms that cause systemic, life-threatening infections in humans reside as harmless commensals in our digestive tract. Yet little is known about the biology of these microbes in the gut. Here, we visualize the interface between the human commensal and pathogenic fungus Candida albicans and the intestine of mice, a surrogate host. Because the indigenous mouse microbiota restricts C. albicans settlement, we compared the patterns of colonization in the gut of germ free and antibiotic-treated conventionally raised mice. In contrast to the heterogeneous morphologies found in the latter, we establish that in germ free animals the fungus almost uniformly adopts the yeast cell form, a proxy of its commensal state. By screening a collection of C. albicans transcription regulator deletion mutants in gnotobiotic mice, we identify several genes previously unknown to contribute to in vivo fitness. We investigate three of these regulators—ZCF8, ZFU2 and TRY4—and show that indeed they favor the yeast form over other morphologies. Consistent with this finding, we demonstrate that genetically inducing non-yeast cell morphologies is detrimental to the fitness of C. albicans in the gut. Furthermore, the identified regulators promote adherence of the fungus to a surface covered with mucin and to mucus-producing intestinal epithelial cells. In agreement with this result, histology sections indicate that C. albicans dwells in the murine gut in close proximity to the mucus layer. Thus, our findings reveal a set of regulators that endows C. albicans with the ability to endure in the intestine through multiple mechanisms. KW - Candida albicans KW - deletion mutagenesis KW - gastrointestinal tract KW - fungi KW - regulator genes KW - gene regulation KW - mouse models KW - fungal genetics Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-159120 VL - 13 IS - 10 ER - TY - JOUR A1 - Hampe, Irene A. I. A1 - Friedman, Justin A1 - Edgerton, Mira A1 - Morschhäuser, Joachim T1 - An acquired mechanism of antifungal drug resistance simultaneously enables Candida albicans to escape from intrinsic host defenses JF - PLoS Pathogens N2 - The opportunistic fungal pathogen Candida albicans frequently produces genetically altered variants to adapt to environmental changes and new host niches in the course of its life-long association with the human host. Gain-of-function mutations in zinc cluster transcription factors, which result in the constitutive upregulation of their target genes, are a common cause of acquired resistance to the widely used antifungal drug fluconazole, especially during long-term therapy of oropharyngeal candidiasis. In this study, we investigated if C. albicans also can develop resistance to the antimicrobial peptide histatin 5, which is secreted in the saliva of humans to protect the oral mucosa from pathogenic microbes. As histatin 5 has been shown to be transported out of C. albicans cells by the Flu1 efflux pump, we screened a library of C. albicans strains that contain artificially activated forms of all zinc cluster transcription factors of this fungus for increased FLU1 expression. We found that a hyperactive Mrr1, which confers fluconazole resistance by upregulating the multidrug efflux pump MDR1 and other genes, also causes FLU1 overexpression. Similarly to the artificially activated Mrr1, naturally occurring gain-of-function mutations in this transcription factor also caused FLU1 upregulation and increased histatin 5 resistance. Surprisingly, however, Mrr1-mediated histatin 5 resistance was mainly caused by the upregulation of MDR1 instead of FLU1, revealing a previously unrecognized function of the Mdr1 efflux pump. Fluconazole-resistant clinical C. albicans isolates with different Mrr1 gain-of-function mutations were less efficiently killed by histatin 5, and this phenotype was reverted when MRR1 was deleted. Therefore, antimycotic therapy can promote the evolution of strains that, as a consequence of drug resistance mutations, simultaneously have acquired increased resistance against an innate host defense mechanism and are thereby better adapted to certain host niches. KW - antimicrobial resistance KW - transcriptional control KW - Candida albicans KW - transcription factors KW - mutation KW - hyperexpression techniques KW - antifungals KW - point mutation Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-158883 VL - 13 IS - 9 ER - TY - JOUR A1 - Tawk, Caroline A1 - Sharan, Malvika A1 - Eulalio, Ana A1 - Vogel, Jörg T1 - A systematic analysis of the RNA-targeting potential of secreted bacterial effector proteins JF - Scientific Reports N2 - Many pathogenic bacteria utilize specialized secretion systems to deliver proteins called effectors into eukaryotic cells for manipulation of host pathways. The vast majority of known effector targets are host proteins, whereas a potential targeting of host nucleic acids remains little explored. There is only one family of effectors known to target DNA directly, and effectors binding host RNA are unknown. Here, we take a two-pronged approach to search for RNA-binding effectors, combining biocomputational prediction of RNA-binding domains (RBDs) in a newly assembled comprehensive dataset of bacterial secreted proteins, and experimental screening for RNA binding in mammalian cells. Only a small subset of effectors were predicted to carry an RBD, indicating that if RNA targeting was common, it would likely involve new types of RBDs. Our experimental evaluation of effectors with predicted RBDs further argues for a general paucity of RNA binding activities amongst bacterial effectors. We obtained evidence that PipB2 and Lpg2844, effector proteins of Salmonella and Legionella species, respectively, may harbor novel biochemical activities. Our study presenting the first systematic evaluation of the RNA-targeting potential of bacterial effectors offers a basis for discussion of whether or not host RNA is a prominent target of secreted bacterial proteins. KW - pathogens KW - bacterial secretion Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-158815 VL - 7 ER - TY - JOUR A1 - Rakette, Sonja A1 - Donat, Stefanie A1 - Ohlsen, Knut A1 - Stehle, Thilo T1 - Structural Analysis of Staphylococcus aureus Serine/Threonine Kinase PknB JF - PLoS One N2 - Effective treatment of infections caused by the bacterium Staphylococcus aureus remains a worldwide challenge, in part due to the constant emergence of new strains that are resistant to antibiotics. The serine/threonine kinase PknB is of particular relevance to the life cycle of S. aureus as it is involved in the regulation of purine biosynthesis, autolysis, and other central metabolic processes of the bacterium. We have determined the crystal structure of the kinase domain of PknB in complex with a non-hydrolyzable analog of the substrate ATP at 3.0 angstrom resolution. Although the purified PknB kinase is active in solution, it crystallized in an inactive, autoinhibited state. Comparison with other bacterial kinases provides insights into the determinants of catalysis, interactions of PknB with ligands, and the pathway of activation. KW - SER/THR kinase KW - domain KW - subunit KW - dependent protein-kinase KW - mycobacterium-tuberculosis KW - activation mechanism KW - crystal structure KW - antibiotic resistance KW - catalytic KW - methicillin KW - inhibitor Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-135369 VL - 7 IS - 6 ER - TY - THES A1 - Hampe, Irene Aurelia Ida T1 - Analysis of the mechanism and the regulation of histatin 5 resistance in \(Candida\) \(albicans\) T1 - Analyse des Mechanismus und der Regulierung von Histatin 5 Resistenz in \(Candida\) \(albicans\) N2 - Antimycotics such as fluconazole are frequently used to treat C. albicans infections of the oral mucosa. Prolonged treatment of the fungal infection with fluconazole pose a risk to resistance development. C. albicans can adapt to these stressful environmental changes by regulation of gene expression or by producing genetically altered variants that arise in the population. Adapted variants frequently carry activating mutations in zinc cluster transcription factors, which cause the upregulation of their target genes, including genes encoding efflux pumps that confer drug resistance. MDR1, regulated by the zinc cluster transcription factor Mrr1, as well as CDR1 and CDR2, regulated by the zinc cluster transcription factor Tac1, are well-known examples of genes encoding efflux pumps that extrude the antimycotic fluconazole from the fungal cell and thus contribute to the survival of the fungus. In this study, it was investigated if C. albicans can develop resistance to the antimicrobial peptide histatin 5, which serves as the first line of defence in the oral cavity of the human host. Recently, it was shown that C. albicans transports histatin 5 outside of the Candia cell via the efflux pump Flu1. As efflux pumps are often regulated by zinc cluster transcription factors, the Flu1 efflux pump could also be regulated by a zinc cluster transcription factor which could in a hyperactive form upregulate the expression of the efflux pump, resulting in increased export of histatin 5 and consequently in histatin 5 resistance. In order to find a zinc cluster transcription factor that upregulates FLU1 expression, a comprehensive library of C. albicans strains containing artificially activated forms of zinc cluster transcription factors was screened for suitable candidates. The screening was conducted on medium containing mycophenolic acid because mycophenolic acid is also a substrate of Flu1 and a strain expressing a hyperactive zinc cluster transcription factor that upregulates FLU1 expression should exhibit an easily recognisable mycophenolic acid-resistant phenotype. Further, FACS analysis, quantitative real-time RT-PCR analysis, broth microdilution assays as well as histatin 5 assays were conducted to analyse the mechanism and the regulation of histatin 5 resistance. Several zinc cluster transcription factors caused mycophenolic acid resistance and upregulated FLU1 expression. Of those, only hyperactive Mrr1 was able to confer increased histatin 5 resistance. Finding Mrr1 to confer histatin 5 resistance was highly interesting as fluconazole-resistant strains with naturally occurring Mrr1 gain of function mutations exist, which were isolated from HIV-infected patients with oral candidiasis. These Mrr1 gain of function mutations as well as artificially activated Mrr1 cause fluconazole resistance by upregulation of the efflux pump MDR1 and other target genes. In the course of the study, it was found that expression of different naturally occurring MRR1 gain-of-function mutations in the SC5314 wild type background caused increased FLU1 expression and increased histatin 5 resistance. The same was true for fluconazole-resistant clinical isolates with Mrr1 gain of function mutations, which also caused the overexpression of FLU1. Those cells were less efficiently killed by histatin 5 dependent on Mrr1. Surprisingly, FLU1 contributed only little to histatin 5 resistance, rather, overexpression of MDR1 mainly contributed to the Mrr1-mediated histatin 5 resistance, but also additional Mrr1-target genes were involved. These target genes are yet to be uncovered. Moreover, if a link between the yet unknown Mrr1-target genes contributing to fluconazole resistance and increased histatin 5 resistance can be drawn remains to be discovered upon finding of the responsible target genes. Collectively, this study contributes to the understanding of the impact of prolonged antifungal exposure on the interaction between host and fungus. Drug therapy can give rise to resistance evolution resulting in strains that have not only developed resistance to fluconazole but also to an innate host mechanism, which allows adaption to the host niche even in the absence of the drug. N2 - Antimykotika wie Fluconazol werden häufig zur Behandlung von C. albicans Infektionen der Mundschleimhaut verwendet. Dabei stellt eine langzeitige Behandlung der Pilzinfektion mit Fluconazol ein Risiko zur Resistenzentwicklung dar. C. albicans kann sich an solche Umweltveränderungen anpassen, indem es die Genexpression reguliert oder genetisch veränderte Varianten produziert, welche in der Population entstehen. Adaptierte Varianten tragen häufig aktivierende Mutationen in Zink-Cluster-Transkriptionsfaktoren, welche die Hochregulierung der Expression von Genen verursachen, darunter solche, die für Multidrug-Effluxpumpen kodieren und dadurch Antimykotikaresistenz verleihen können. MDR1, reguliert durch den Zink-Cluster-Transkriptionsfaktor Mrr1, sowie CDR1 und CDR2, reguliert durch den Zink-Cluster-Transkriptionsfaktor Tac1, sind bekannte Beispiele für Effluxpumpen, die das Antimykotikum Fluconazol aus der Pilzzelle extrudieren und somit zum Überleben der Pilzzelle beitragen. In dieser Arbeit wurde untersucht, ob C. albicans eine Resistenz gegen das antimikrobielle Peptid Histatin 5 entwickeln kann, das in der Mundhöhle des menschlichen Wirtes als erste Verteidigungsbarriere gegen den Pilz dient. Kürzlich wurde gezeigt, dass C. albicans Histatin 5 über die Effluxpumpe Flu1 aus der Candia-Zelle heraustransportiert (Li et al., 2013). Da Effluxpumpen häufig durch Zink-Cluster-Transkriptionsfaktoren reguliert werden, könnte auch die Flu1-Effluxpumpe durch solch einen Transkriptionsfaktor reguliert werden, der in einer hyperaktiven Form die Expression der Effluxpumpe hochregulieren könnte, was wiederrum zu einem erhöhten Export von Histatin 5 und folglich zur Histatin 5 Resistenz führen könnte. Um einen Zink-Cluster-Transkriptionsfaktor zu finden, der die FLU1-Expression hochreguliert, wurde mit Hilfe einer Bibliothek von C. albicans-Stämmen, die künstlich aktivierte Formen von Zink-Cluster-Transkriptionsfaktoren enthält, nach geeigneten Kandidaten gesucht. Das Screening wurde auf Mycophenolsäure-haltigem Medium durchgeführt, da Mycophenolsäure ebenfalls ein Substrat von Flu1 ist. Folglich sollte ein Stamm mit hyperaktivem Zink-Cluster-Transkriptionsfaktor, welcher die FLU1-Expression hochreguliert, einen leicht erkennbaren Mycophenolsäure-resistenten Phänotyp aufweisen. Weiterhin wurden FACS-Analysen, quantitative real-time RT-PCR-Analysen, Broth microdilution-Assays sowie Histatin 5-Assays durchgeführt, um den Mechanismus und die Regulierung der Histatin-5-Resistenz zu analysieren. Mehrere Zink-Cluster-Transkriptionsfaktoren verursachten Mycophenolsäure-Resistenz und erhöhten die FLU1-Expression. Von diesen war nur hyperaktives Mrr1 in der Lage, eine erhöhte Histatin-5-Resistenz zu verleihen. Das Auffinden von Mrr1 als Regulator der Histatin 5-Resistenz war hochinteressant, da fluconazolresistente Stämme mit natürlich vorkommenden MRR1 gain-of-function Mutationen existieren, die aus HIV-infizierten Patienten mit oropharyngealer Candidiasis isoliert wurden. Diese gain-of-function Mutationen sowie künstlich aktivierendes Mrr1 verursachen Fluconazol-Resistenz durch Hochregulation der Effluxpumpe MDR1 und anderer Zielgene. Im Verlauf der Studie wurde herausgefunden, dass verschiedene natürlich vorkommende MRR1 gain-of-function Mutationen im SC5314 Wildtyp Hintergrund eine erhöhte FLU1-Expression und eine erhöhte Histatin-5-Resistenz verursachten. Das Gleiche galt für Fluconazol-resistente klinische Isolate mit Mrr1 gain-of-function Mutationen, welche die Überexpression von FLU1 verursachten. Zellen dieser Isolate wurden, abhängig von Mrr1, weniger wirksam durch Histatin 5 abgetötet. Überraschenderweise trug FLU1 nur wenig zur Histatin-5-Resistenz bei, vielmehr trug die Überexpression von MDR1 hauptsächlich zur Mrr1-vermittelten Histatin-5-Resistenz bei, aber auch weitere Mrr1-Zielgene waren daran beteiligt. Diese Mrr1-Zielgene gilt es nun noch zu entdecken. Ob ein Zusammenhang zwischen diesen noch unbekannten Mrr1-Zielgenen hergestellt werden kann, die zur Fluconazolresistenz sowie zu einer erhöhten Histatin-5-Resistenz beitragen, wird erst nach dem Auffinden der verantwortlichen Zielgene geprüft werden können. Zusammenfassend trägt diese Studie zum Verständnis der Auswirkungen einer anhaltenden antimykotischen Exposition auf die Interaktion zwischen Wirt und Pilz bei. Eine medikamentöse Therapie kann zu einer Resistenzentwicklung führen, aus der Stämme hervorgehen, welche nicht nur eine Resistenz gegen Fluconazol entwickelt haben, sondern gleichzeitig eine Resistenz gegen einen angeborenen Wirtsabwehrmechanismus, der eine Adaption an die Wirtsnische auch in Abwesenheit des Antimykotikums ermöglicht. KW - Histatin 5 KW - Candida albicans KW - Efflux pump KW - MDR1 KW - MRR1 KW - Mrr1 KW - MDR1 KW - Fluconazole KW - Efflux pump Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-159634 ER - TY - JOUR A1 - Sunkavalli, Ushasree A1 - Aguilar, Carmen A1 - Silva, Ricardo Jorge A1 - Sharan, Malvika A1 - Cruz, Ana Rita A1 - Tawk, Caroline A1 - Maudet, Claire A1 - Mano, Miguel A1 - Eulalio, Ana T1 - Analysis of host microRNA function uncovers a role for miR-29b-2-5p in Shigella capture by filopodia JF - PLoS Pathogens N2 - MicroRNAs play an important role in the interplay between bacterial pathogens and host cells, participating as host defense mechanisms, as well as exploited by bacteria to subvert host cellular functions. Here, we show that microRNAs modulate infection by Shigella flexneri, a major causative agent of bacillary dysentery in humans. Specifically, we characterize the dual regulatory role of miR-29b-2-5p during infection, showing that this microRNA strongly favors Shigella infection by promoting both bacterial binding to host cells and intracellular replication. Using a combination of transcriptome analysis and targeted high-content RNAi screening, we identify UNC5C as a direct target of miR-29b-2-5p and show its pivotal role in the modulation of Shigella binding to host cells. MiR-29b-2-5p, through repression of UNC5C, strongly enhances filopodia formation thus increasing Shigella capture and promoting bacterial invasion. The increase of filopodia formation mediated by miR-29b-2-5p is dependent on RhoF and Cdc42 Rho-GTPases. Interestingly, the levels of miR-29b-2-5p, but not of other mature microRNAs from the same precursor, are decreased upon Shigella replication at late times post-infection, through degradation of the mature microRNA by the exonuclease PNPT1. While the relatively high basal levels of miR-29b-2-5p at the start of infection ensure efficient Shigella capture by host cell filopodia, dampening of miR-29b-2-5p levels later during infection may constitute a bacterial strategy to favor a balanced intracellular replication to avoid premature cell death and favor dissemination to neighboring cells, or alternatively, part of the host response to counteract Shigella infection. Overall, these findings reveal a previously unappreciated role of microRNAs, and in particular miR-29b-2-5p, in the interaction of Shigella with host cells. KW - hos tcells KW - Salmonellosis KW - Shigellosis KW - microRNAs KW - Shigella KW - small interfering RNAs KW - HeLa cells KW - Cell binding Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-158204 VL - 13 IS - 4 ER -