Thomas F Meyer

Publications (146)724.45 Total impact

• Article: Chlamydia trachomatis infection prevents front-rear polarity of migrating HeLa cells.

  Julia Heymann, Anette Rejman Lipinski, Bianca Bauer, Thomas F Meyer, Dagmar Heuer
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  ABSTRACT: Chlamydiae are obligate intracellular bacterial pathogens that cause trachoma, sexually transmitted diseases and respiratory infections in humans. Fragmentation of the host cell Golgi apparatus (GA) is essential for chlamydial development, whereas the consequences for host cell functions, including cell migration are not well understood. We could show that Chlamydia trachomatis-infected cells display decelerated migration and fail to repopulate monolayer scratch wounds. Furthermore, infected cells lost the ability to reorient the fragmented GA or the microtubule organization centre (MTOC) after a migratory stimulus. Silencing of golgin-84 phenocopied this defect in the absence of the infection. Interestingly, GA stabilisation via knockdown of Rab6A and Rab11A improved its reorientation in infected cells and it was fully rescued after inhibition of Golgi fragmentation with WEHD-fmk. These results show that C. trachomatis infection perturbs host cell migration on multiple levels, including the alignment of GA and MTOC.
  Cellular Microbiology 01/2013; · 5.46 Impact Factor
• Article: Autophagy restricts Chlamydia trachomatis growth in human macrophages via IFNG-inducible guanylate binding proteins.

  Munir A Al-Zeer, Hesham M Al-Younes, Daniel Lauster, Mohammad Abu Lubad, Thomas F Meyer
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  ABSTRACT: Interferon γ (IFNG) is a key host response regulator of intracellular pathogen replication, including that of Chlamydia spp The antichlamydial functions of IFNG manifest in a strictly host, cell-type and chlamydial strain dependent manner. It has been recently shown that the IFNG-inducible family of immunity-related GTPases (IRG) proteins plays a key role in the defense against nonhost adapted chlamydia strains in murine epithelial cells. In humans, IFN-inducible guanylate binding proteins (hGBPs) have been shown to potentiate the antichlamydial effect of IFNG; however, how hGBPs regulate this property of IFNG is unknown. In this study, we identified hGBP1/2 as important resistance factors against C. trachomatis infection in IFNG-stimulated human macrophages. Exogenous IFNG reduced chlamydial infectivity by 50 percent in wild-type cells, whereas shRNA hGBP1/2 knockdown macrophages fully supported chlamydial growth in the presence of exogenous IFNG. hGBP1/2 were recruited to bacterial inclusions in human macrophages upon stimulation with IFNG, which triggered rerouting of the typically nonfusogenic bacterial inclusions for lysosomal degradation. Inhibition of lysosomal activity and autophagy impaired the IFNG-mediated elimination of inclusions. Thus, hGBP1/2 are critical effectors of antichlamydial IFNG responses in human macrophages. Through their capacity to remodel classically nonfusogenic chlamydial inclusions and stimulate fusion with autophagosomes, hGBP1/2 disable a major chlamydial virulence mechanism and contribute to IFNG-mediated pathogen clearance.
  Autophagy 10/2012; 9(1). · 7.45 Impact Factor
• Article: Sensing the enemy: New role for a bacterial secretion system in activation of an innate immunity-associated microRNA.

  Manuel Koch, Kate Holden-Dye, Thomas F Meyer
  Virulence 10/2012; 3(6). · 2.26 Impact Factor
• Article: In vivo sequence variation in HopZ, a phase variable outer membrane protein of Helicobacter pylori.

  Lynn Kennemann, Birgit Brenneke, Sönke Andres, Lars Engstrand, Thomas F Meyer, Toni Aebischer, Christine Josenhans, Sebastian Suerbaum
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  ABSTRACT: The H. pylori outer membrane protein HopZ is regulated by a phase variable CT repeat and occurs in two distinct allelic variants. Whole genome comparisons of isolates from one human volunteer recently provided evidence for in vivo selection for the hopZ ON status. We explored the frequency of sequence variation in hopZ during acute and chronic human infection, and studied the association of hopZ with the phylogeographic population structure of H. pylori.hopZ ON variants were cultured from 24 out of 33 volunteers challenged with the hopZ OFF strain BCS 100. Transmission of H. pylori within families was also frequently associated with a status change of hopZ. In contrast, hopZ sequences obtained from 26 sets of sequential isolates from chronically infected individuals showed no changes of status, suggesting that the hopZ status selected during early infection is subsequently stable. Mutations leading to amino acid changes in HopZ occurred more frequently in ON than in OFF status isolates during chronic infection, indicating that sequence changes are more likely the result of positive selection in ON isolates than of a loss of negative selection pressure in OFF isolates.Analysis of 63 isolates from chronically infected individuals revealed no significant correlation of hopZ status with chronic atrophic gastritis.hopZ sequences were obtained from a globally representative collection of 54 H. pylori strains. All H. pylori populations contained hopZ positive isolates. The data suggest that hopZ has been acquired and split into the two variants before the human migration out of Africa.
  Infection and immunity 10/2012; · 4.21 Impact Factor
• Source

  Available from: Tim Mak

  Article: Propionibacterium acnes host cell tropism contributes to vimentin-mediated invasion and induction of inflammation.

  Tim N Mak, Natalie Fischer, Britta Laube, Volker Brinkmann, Matteo M E Metruccio, Karen S Sfanos, Hans-Joachim Mollenkopf, Thomas F Meyer, Holger Brüggemann
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  ABSTRACT: The contribution of the human microbiota to health and disease is poorly understood. Propionibacterium acnes is a prominent member of the skin microbiota, but is also associated with acne vulgaris. This bacterium has gained recent attention as a potential opportunistic pathogen at non-skin infection sites due to its association with chronic pathologies and its isolation from diseased prostates. We performed comparative global-transcriptional analyses for P. acnes infection of keratinocytes and prostate cells. P. acnes induced an acute, transient transcriptional inflammatory response in keratinocytes, whereas this response was delayed and sustained in prostate cells. We found that P. acnes invaded prostate epithelial cells, but not keratinocytes, and was detectable intracellularly 7 days post infection. Further characterization of the host cell response to infection revealed that vimentin was a key determinant for P. acnes invasion in prostate cells. siRNA-mediated knock-down of vimentin in prostate cellsattenuated bacterial invasion and the inflammatory response to infection. We conclude that host cell tropism, which may depend on the host protein vimentin, is relevant for P. acnes invasion and in part determines its sustained inflammatory capacity and persistence of infection.
  Cellular Microbiology 07/2012; 14(11):1720-33. · 5.46 Impact Factor
• Article: The Helicobacter pylori virulence effector CagA abrogates human β-defensin 3 expression via inactivation of EGFR signaling.

  Bianca Bauer, Ervinna Pang, Carsten Holland, Mirjana Kessler, Sina Bartfeld, Thomas F Meyer
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  ABSTRACT: Antimicrobial peptides are constituents of the first-line innate mucosal defense system that acts as a barrier to establishment of infection. The highly successful human gastric pathogen, Helicobacter pylori, is able to persistently colonize its host despite inducing expression of several antimicrobial peptides, including human β-defensin 3 (hBD3). We find that hBD3 is highly active against H. pylori in vitro and is rapidly induced during early infection via EGFR-dependent activation of MAP kinase and JAK/STAT signaling. However, during prolonged infection, hBD3 was subsequently downregulated by the H. pylori virulence determinant CagA. Upon translocation into host cells, CagA activated the cellular tyrosine phosphatase, SHP-2, terminating EGFR activation and downstream signaling and increasing bacterial viability. Chemical inhibition and knockdown of SHP-2 expression rescued hBD3 synthesis and bactericidal activity. Thus, we reveal how cagPAI-positive H. pylori strains use CagA to evade a key innate mucosal defense pathway to support the establishment of persistent infection.
  Cell host & microbe 06/2012; 11(6):576-86. · 13.02 Impact Factor
• Article: Comparative analysis of the interaction of Helicobacter pylori with human dendritic cells, macrophages, and monocytes.

  Michael Fehlings, Lea Drobbe, Verena Moos, Pablo Renner Viveros, Jana Hagen, Macarena Beigier-Bompadre, Ervinna Pang, Elena Belogolova, Yuri Churin, Thomas Schneider, Thomas F Meyer, Toni Aebischer, Ralf Ignatius
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  ABSTRACT: Helicobacter pylori may cause chronic gastritis, gastric cancer, or lymphoma. Myeloid antigen-presenting cells (APCs) are most likely involved in the induction and expression of the underlying inflammatory responses. To study the interaction of human APC subsets with H. pylori, we infected monocytes, monocyte-derived dendritic cells (DCs), and monocyte-derived (classically activated; M1) macrophages with H. pylori and analyzed phenotypic alterations, cytokine secretion, phagocytosis, and immunostimulation. Since we detected CD163(+) (alternatively activated; M2) macrophages in gastric biopsy specimens from H. pylori-positive patients, we also included monocyte-derived M2 macrophages in the study. Upon H. pylori infection, monocytes secreted interleukin-1β (IL-1β), IL-6, IL-10, and IL-12p40 (partially secreted as IL-23) but not IL-12p70. Infected DCs became activated, as shown by the enhanced expression of CD25, CD80, CD83, PDL-1, and CCR7, and secreted IL-1β, IL-6, IL-10, IL-12p40, IL-12p70, and IL-23. However, infection led to significantly downregulated CD209 and suppressed the constitutive secretion of macrophage migration inhibitory factor (MIF). H. pylori-infected M1 macrophages upregulated CD14 and CD32, downregulated CD11b and HLA-DR, and secreted mainly IL-1β, IL-6, IL-10, IL-12p40, and IL-23. Activation of DCs and M1 macrophages correlated with increased capacity to induce T-cell proliferation and decreased phagocytosis of dextran. M2 macrophages upregulated CD14 and CD206 and secreted IL-10 but produced less of the proinflammatory cytokines than M1 macrophages. Thus, H. pylori affects the functions of human APC subsets differently, which may influence the course and the outcome of H. pylori infection. The suppression of MIF in DCs constitutes a novel immune evasion mechanism exploited by H. pylori.
  Infection and immunity 05/2012; 80(8):2724-34. · 4.21 Impact Factor
• Source

  Available from: pnas.org

  Article: Induction of microRNA-155 is TLR- and type IV secretion system-dependent in macrophages and inhibits DNA-damage induced apoptosis.

  Manuel Koch, Hans-Joachim Mollenkopf, Uwe Klemm, Thomas F Meyer
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  ABSTRACT: Helicobacter pylori is a gastric pathogen responsible for a high disease burden worldwide. Deregulated inflammatory responses, possibly involving macrophages, are implicated in H. pylori-induced pathology, and microRNAs, such as miR-155, have recently emerged as crucial regulators of innate immunity and inflammatory responses. miR-155 is regulated by Toll-like receptor (TLR) ligands in monocyte-derived cells and has been shown to be induced in macrophages during H. pylori infection. Here, we investigated the regulation of miR-155 expression in primary murine bone marrow-derived macrophages (BMMs) during H. pylori infection and examined the downstream mRNA targets of this microRNA using microarray analysis. We report TLR2/4- and NOD1/2-independent up-regulation of miR-155, which was found to be dependent on the major H. pylori pathogenicity determinant, the type IV secretion system (T4SS). miR-155 expression was dependent on NF-κB signaling but was independent of CagA. Microarray analysis identified known gene targets of miR-155 in BMMs during H. pylori infection that are proapoptotic. We also identified and validated miR-155 binding sites in the 3' UTRs of the targets, Tspan14, Lpin1, and Pmaip1. We observed that H. pylori-infected miR-155(-/-) BMMs were significantly more susceptible to cisplatin DNA damage-induced apoptosis than were wild-type BMMs. Thus, our data suggest a function for the prototypical H. pylori pathogenicity factor, the T4SS, in the up-regulation of miR-155 in BMMs. We propose the antiapoptotic effects of miR-155 could enhance macrophage resistance to apoptosis induced by DNA damage during H. pylori infection.
  Proceedings of the National Academy of Sciences 04/2012; 109(19):E1153-62. · 9.68 Impact Factor
• Article: Chlamydia trachomatis disturbs epithelial tissue homeostasis in fallopian tubes via paracrine Wnt signaling.

  Mirjana Kessler, Julia Zielecki, Oliver Thieck, Hans-Joachim Mollenkopf, Christina Fotopoulou, Thomas F Meyer
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  ABSTRACT: The obligate intracellular pathogen Chlamydia trachomatis (Ctr) is a major cause of sexually transmitted disease and infertility worldwide. Ascending genital infections cause inflammation of fallopian tubes and subsequent scarring and occlusion. The cellular basis for such sequelae remains undetermined. We used confocal immunofluorescence microscopy to show that Ctr disrupts epithelial homeostasis in an ex vivo infection model of human fallopian tubes. Ctr triggered loss of polarity of inclusion harboring cells and of neighboring uninfected cells, as shown by subcellular redistribution of adhesion and polarity (occludin) markers. β-catenin (a component of the adherens junction and a Wnt signaling transducer) was recruited to the bacterial inclusion, suggesting a role for Wnt signaling in Ctr-mediated tissue damage. Comparative microarray analysis of infected epithelium in the presence of the Wnt secretion inhibitor (IWP2) demonstrated that the transcriptional response to Ctr infection was highly dependent on active Wnt secretion, moreover IWP2 reversed Ctr-induced tissue phenotypes. Notably, we observed the up-regulation of differentiation and proliferation biomarkers olfactomedin 4 and epithelial cell adhesion molecule, and also Ctr-induced proteolytic activation of epithelial cell adhesion molecule. Thus, acute Ctr infection activates the paracrine Wnt signaling pathway, leading to profound disruption of epithelial structure and function that facilitates the dissemination of damage beyond that of infected cells.
  American Journal Of Pathology 11/2011; 180(1):186-98. · 4.89 Impact Factor
• Article: Modulation of the CD4+ T-cell response by Helicobacter pylori depends on known virulence factors and bacterial cholesterol and cholesterol α-glucoside content.

  Macarena Beigier-Bompadre, Verena Moos, Elena Belogolova, Kristina Allers, Thomas Schneider, Yuri Churin, Ralf Ignatius, Thomas F Meyer, Toni Aebischer
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  ABSTRACT: Helicobacter pylori blocks the proliferation of human CD4(+) T cells, facilitated by vacuolating exotoxin (VacA) and γ-glutamyl transpeptidase (GGT). H. pylori-triggered T-cell reactions in mice correlate with bacterial cholesterol and cholesterol α-glucoside content but their role in human cells is unclear. We characterized the effect of VacA, GGT, and cholesterol on T-helper 1, T-helper 2, T-regulatory and T-helper 17 associated cytokines and T-cell proliferation. VacA, GGT, and bacterial cholesterol content exhibited differential and synergistic inhibitory effects on the expression of activation markers CD25 and CD69 and on interleukin 2, interleukin 4, interleukin 10, and interferon γ production. These factors did not affect the H. pylori-mediated abrogation of transforming growth factor β secretion or increased interleukin 6 production. Cholesterol α-glucosyltransferase-deficient bacteria exerted strongly reduced antiproliferative effects on primary human CD4(+) T cells. In conclusion, H. pylori shapes rather than suppresses human CD4(+) T-cell responses, and glucosylated cholesterol is a relevant bacterial component involved in this modulation.
  The Journal of Infectious Diseases 09/2011; 204(9):1339-48. · 6.41 Impact Factor
• Source

  Available from: PubMed Central

  Article: Targeting of a chlamydial protease impedes intracellular bacterial growth.

  Jan G Christian, Julia Heymann, Stefan A Paschen, Juliane Vier, Linda Schauenburg, Jan Rupp, Thomas F Meyer, Georg Häcker, Dagmar Heuer
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  ABSTRACT: Chlamydiae are obligate intracellular bacteria that propagate in a cytosolic vacuole. Recent work has shown that growth of Chlamydia induces the fragmentation of the Golgi apparatus (GA) into ministacks, which facilitates the acquisition of host lipids into the growing inclusion. GA fragmentation results from infection-associated cleavage of the integral GA protein, golgin-84. Golgin-84-cleavage, GA fragmentation and growth of Chlamydia trachomatis can be blocked by the peptide inhibitor WEHD-fmk. Here we identify the bacterial protease chlamydial protease-like activity factor (CPAF) as the factor mediating cleavage of golgin-84 and as the target of WEHD-fmk-inhibition. WEHD-fmk blocked cleavage of golgin-84 as well as cleavage of known CPAF targets during infection with C. trachomatis and C. pneumoniae. The same effect was seen when active CPAF was expressed in non-infected cells and in a cell-free system. Ectopic expression of active CPAF in non-infected cells was sufficient for GA fragmentation. GA fragmentation required the small GTPases Rab6 and Rab11 downstream of CPAF-activity. These results define CPAF as the first protein that is essential for replication of Chlamydia. We suggest that this role makes CPAF a potential anti-infective therapeutic target.
  PLoS Pathogens 09/2011; 7(9):e1002283. · 9.13 Impact Factor
• Article: MicroRNA-155 is essential for the T cell-mediated control of Helicobacter pylori infection and for the induction of chronic Gastritis and Colitis.

  Mathias Oertli, Daniela B Engler, Esther Kohler, Manuel Koch, Thomas F Meyer, Anne Müller
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  ABSTRACT: MicroRNAs govern immune responses to infectious agents, allergens, and autoantigens and function by posttranscriptional repression of their target genes. In this paper, we have addressed the role of microRNA-155 (miR-155) in the control of Helicobacter pylori infection of the gastrointestinal tract and the development of H. pylori-induced chronic gastritis and associated gastric preneoplastic pathology. We show that miR-155 is upregulated in the gastric mucosa of experimentally infected mice and that miR-155(-/-) mice fail to control H. pylori infection as a result of impaired pathogen-specific Th1 and Th17 responses. miR-155(-/-) mice are also less well protected against challenge infection after H. pylori-specific vaccination than their wild-type (wt) counterparts. As a consequence of their impaired T cell responses to H. pylori, miR-155(-/-) mice develop less severe infection-induced immunopathology manifesting as chronic atrophic gastritis, epithelial hyperplasia, and intestinal metaplasia. T cells from miR-155(-/-) mice that are activated by CD3/CD28 cross-linking expand less and produce less IFN-γ and IL-17 than wt T cells. Finally, we show in this paper using adoptive transfers that the phenotypes of miR-155(-/-) mice are likely due to T cell-intrinsic defects. In contrast to wt T cells, miR-155(-/-) T cells from infected donors do not control H. pylori infections in T cell-deficient recipients, do not differentiate into Th1 or Th17 cells, and do not cause immunopathology. In addition, naive miR-155(-/-) T cells fail to induce chronic Th17-driven colitis in an adoptive transfer model. In conclusion, miR-155 expression is required for the Th17/Th1 differentiation that underlies immunity to H. pylori infection on the one hand and infection-associated immunopathology on the other.
  The Journal of Immunology 08/2011; 187(7):3578-86. · 5.79 Impact Factor
• Article: HIF-1α is involved in mediating apoptosis resistance to Chlamydia trachomatis-infected cells.

  Manu Sharma, Nikolaus Machuy, Linda Böhme, Karthika Karunakaran, André P Mäurer, Thomas F Meyer, Thomas Rudel
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  ABSTRACT: Chlamydiae are obligate intracellular Gram-negative bacteria that cause widespread diseases in humans. Due to the intimate association between bacterium and host, Chlamydia evolved various strategies to protect their host cell against death-inducing stimuli, allowing the bacterium to complete its development cycle. An RNA interference (RNAi)-based screen was used to identify host cell factors required for apoptosis resistance of human epithelial cells infected with Chlamydia trachomatis serovar L2. Among the 32 validated hits, the anti-apoptotic Bcl-2 family member Mcl-1 was identified as a target. Protein network analyses implicated the transcription factor hypoxia-induced factor 1 alpha (HIF-1α) to be central to the regulation of many of the identified targets. Further mechanistic investigations showed that HIF-1α was stabilized within the host cell cytoplasm during early infection time points, followed by its translocation to the nucleus and eventual transcriptional activation of Mcl-1. siRNA-mediated depletion of HIF-1α led to a drastic decrease in Mcl-1, rendering the cell sensitive to apoptosis induction. Taken together, our findings identify HIF-1α as responsible for upregulation of Mcl-1 and the maintenance of apoptosis resistance during Chlamydia infection.
  Cellular Microbiology 08/2011; 13(10):1573-85. · 5.46 Impact Factor
• Source

  Available from: Hany Khalil

  Article: Autophagy-independent function of MAP-LC3 during intracellular propagation of Chlamydia trachomatis.

  Hesham M Al-Younes, Munir A Al-Zeer, Hany Khalil, Joscha Gussmann, Alexander Karlas, Nikolaus Machuy, Volker Brinkmann, Peter R Braun, Thomas F Meyer
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  ABSTRACT: Microtubule-associated protein 1 (MAP1) light chain 3 (LC3) has proven useful as autophagosomal marker in studies on the interaction between pathogens and the host autophagic machinery. However, the function of LC3 is known to extend above and beyond its role in autophagosome formation. We previously reported that intrinsic LC3 is associated with the intracellular Chlamydia trachomatis inclusion in human epithelial cells. Here we show that LC3, most likely the cytoplasmic nonlipidated form, interacts with the C. trachomatis inclusion as a microtubule-associated protein rather than an autophagosome-associated component. In contrast, N-terminally GFP-tagged LC3 exclusively targets autophagosomes rather than chlamydial inclusions. Immunofluorescence analysis revealed an association of LC3 and MAP1 subunits A and B with the inclusion as early as 18 h post infection. Inclusion-bound LC3 was connected with the microtubular network. Depolymerization of the microtubular architecture disrupted the association of LC3/MAP1s with the inclusion. Furthermore, siRNA-mediated silencing of the MAP1 and LC3 proteins revealed their essential function in the intracellular growth of C. trachomatis. Interestingly, defective autophagy remarkably enhanced chlamydial growth, suggesting a suppressive effect of the autophagic machinery on bacterial development. However, depletion of LC3 in autophagy-deficient cells noticeably reduced chlamydial propagation. Thus, our findings demonstrate a new function for LC3, distinct from autophagy, in intracellular bacterial pathogenesis.
  Autophagy 08/2011; 7(8):814-28. · 7.45 Impact Factor
• Article: Quantitative phosphoproteomics reveals link between Helicobacter pylori infection and RNA splicing modulation in host cells.

  Carsten Holland, Monika Schmid, Ursula Zimny-Arndt, John Rohloff, Robert Stein, Peter R Jungblut, Thomas F Meyer
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  ABSTRACT: The Gram-negative, spiral-shaped bacterium Helicobacter pylori is a common human pathogen that causes chronic inflammation of the human gastric mucosa, leading to peptic ulceration and/or gastric cancer. Here, we analyzed changes in the phosphoproteome of gastric epithelial cells (AGS) upon infection with H. pylori using a combination of SILAC, phosphoprotein enrichment, 2-DE, and MALDI TOF/TOF-MS. From a total of 526 spots we identified 391 protein species (143 proteins) and quantified 332 (127 proteins). Nearly, one-third of the identified proteins (40/143) were associated with the spliceosome or RNA splicing. The abundance of 20 proteins was altered by H. pylori infection, in particular, a number of serine arginine-rich (SR) proteins involved in the regulation and control of alternative splicing. Importantly, the combined methodologies enabled the detection of infection-dependent protein species-specific regulation, suggesting functional modulation of individual protein species. These findings reveal unexpected new insights into the mechanisms of host cell manipulation by H. pylori, which are likely associated with gastric pathologies, including gastric cancer.
  Proteomics 07/2011; 11(14):2798-811. · 4.43 Impact Factor
• Article: Activation of NF-κB by Neisseria gonorrhoeae is associated with microcolony formation and type IV pilus retraction.

  Manuela Dietrich, Sina Bartfeld, Rebekka Munke, Claudia Lange, Lesley A Ogilvie, Alexandra Friedrich, Thomas F Meyer
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  ABSTRACT: The early stage of infection with Neisseria gonorrhoeae (Ngo), the causative agent of gonorrhoea, is marked by type IV pilus (Tfp)-mediated attachment and the formation of bacterial microcolonies on epithelial cells. Retraction of the Ngo Tfp generates substantial force on its substrate which can elicit host cell signalling. Here, we observed that this retraction force could also activate nuclear factor (NF)-κB, the central signalling cascade of innate immunity. Using a p65-GFP-expressing epithelial cell line, we show that piliated Ngo induce asynchronous NF-κB activation in infected cells, which is temporally associated with the formation of gonococcal microcolonies. A mutant lacking PilT, an ATPase necessary for Tfp retraction, induced markedly reduced NF-κB activation. This was accompanied by decreased NF-κB target gene transcription and cytokine release. The impaired ability of the pilT mutant to activate NF-κB was compensated by applying mechanical shear stress to the infected host cells, indicating that the mechanical forces generated by retractile pili are involved in the retraction-dependent activation of NF-κB elicited by gonococcal microcolonies. Thus, our work provides evidence for an intriguing relationship between microcolony growth, pilus retraction and host cell signalling, with likely implications with regard to the course of symptomatic versus asymptomatic gonococcal infections.
  Cellular Microbiology 05/2011; 13(8):1168-82. · 5.46 Impact Factor
• Source

  Available from: pnas.org

  Article: Helicobacter pylori genome evolution during human infection.

  Lynn Kennemann, Xavier Didelot, Toni Aebischer, Stefanie Kuhn, Bernd Drescher, Marcus Droege, Richard Reinhardt, Pelayo Correa, Thomas F Meyer, Christine Josenhans, Daniel Falush, Sebastian Suerbaum
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  ABSTRACT: High genetic diversity is a hallmark of the gastric pathogen Helicobacter pylori. We used 454 sequencing technology to perform whole-genome comparisons for five sets of H. pylori strains that had been sequentially cultured from four chronically infected Colombians (isolation intervals=3-16 y) and one human volunteer experimentally infected with H. pylori as part of a vaccine trial. The four sets of genomes from Colombian H. pylori differed by 27-232 isolated SNPs and 16-441 imported clusters of polymorphisms resulting from recombination. Imports (mean length=394 bp) were distributed nonrandomly over the chromosome and frequently occurred in groups, suggesting that H. pylori first takes up long DNA fragments, which subsequently become partially integrated in multiple shorter pieces. Imports were present at significantly increased frequency in members of the hop family of outer membrane gene paralogues, some of which are involved in bacterial adhesion, suggesting diversifying selection. No evidence of recombination and few other differences were identified in the strain pair from an infected volunteer, indicating that the H. pylori genome is stable in the absence of mixed infection. Among these few differences was an OFF/ON switch in the phase-variable adhesin gene hopZ, suggesting strong in vivo selection for this putative adhesin during early colonization.
  Proceedings of the National Academy of Sciences 03/2011; 108(12):5033-8. · 9.68 Impact Factor
• Article: Membrane-SPINE: an improved method to identify protein-protein interaction partners of membrane proteins in vivo.

  Volker S Müller, Peter R Jungblut, Thomas F Meyer, Sabine Hunke
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  ABSTRACT: Membrane proteins are crucial for many essential cellular processes. As membrane proteins function in complexes, methods to detect and to characterize membrane protein-protein interactions are undoubtedly required. Therefore, we developed the "Membrane-Strep-tagged protein interaction experiment" (Membrane-SPINE) that combines the specific purification of a Strep-tagged membrane protein with the reversible fixation of protein complexes by formaldehyde cross-linking. In combination with MS analysis, we suggest Membrane-SPINE as a powerful tool to identify unknown interaction partners of membrane proteins in vivo.
  Proteomics 03/2011; 11(10):2124-8. · 4.43 Impact Factor
• Source

  Available from: January Weiner

  Article: Comparative genomics and transcriptomics of Propionibacterium acnes.

  Elzbieta Brzuszkiewicz, January Weiner, Antje Wollherr, Andrea Thürmer, Jennifer Hüpeden, Hans B Lomholt, Mogens Kilian, Gerhard Gottschalk, Rolf Daniel, Hans-Joachim Mollenkopf, Thomas F Meyer, Holger Brüggemann
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  ABSTRACT: The anaerobic gram-positive bacterium Propionibacterium acnes is a human skin commensal that is occasionally associated with inflammatory diseases. Recent work has indicated that evolutionary distinct lineages of P. acnes play etiologic roles in disease while others are associated with maintenance of skin homeostasis. To shed light on the molecular basis for differential strain properties, we carried out genomic and transcriptomic analysis of distinct P. acnes strains. We sequenced the genome of the P. acnes strain 266, a type I-1a strain. Comparative genome analysis of strain 266 and four other P. acnes strains revealed that overall genome plasticity is relatively low; however, a number of island-like genomic regions, encoding a variety of putative virulence-associated and fitness traits differ between phylotypes, as judged from PCR analysis of a collection of P. acnes strains. Comparative transcriptome analysis of strains KPA171202 (type I-2) and 266 during exponential growth revealed inter-strain differences in gene expression of transport systems and metabolic pathways. In addition, transcript levels of genes encoding possible virulence factors such as dermatan-sulphate adhesin, polyunsaturated fatty acid isomerase, iron acquisition protein HtaA and lipase GehA were upregulated in strain 266. We investigated differential gene expression during exponential and stationary growth phases. Genes encoding components of the energy-conserving respiratory chain as well as secreted and virulence-associated factors were transcribed during the exponential phase, while the stationary growth phase was characterized by upregulation of genes involved in stress responses and amino acid metabolism. Our data highlight the genomic basis for strain diversity and identify, for the first time, the actively transcribed part of the genome, underlining the important role growth status plays in the inflammation-inducing activity of P. acnes. We argue that the disease-causing potential of different P. acnes strains is not only determined by the phylotype-specific genome content but also by variable gene expression.
  PLoS ONE 01/2011; 6(6):e21581. · 4.09 Impact Factor
• Article: Genome-wide RNAi screen for viral replication in mammalian cell culture.

  Bhupesh K Prusty, Alexander Karlas, Thomas F Meyer, Thomas Rudel
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  ABSTRACT: Influenza infections are considered a global threat to public health and cause seasonal epidemics and recurring pandemics. High mutation rates facilitate the generation of viral escape mutants rendering vaccines and drugs directed against virus-encoded targets ineffective. One alternative approach that could prevent viral escape is the targeting of host cell determinants that are temporarily dispensable for the host but crucial for virus replication. Here, we report a genome-wide RNAi screening approach in mammalian cell culture system that led us to the identification of several host cell genes influencing influenza A virus replication. Interestingly, the majority of the identified host gene products are indispensable for viral replication of a broad range of influenza viruses ranging from the highly pathogenic avian H5N1 strain to the current pandemic swine-origin H1N1 strain. Our results provide a new approach to explore virus-host interactions and to identify promising antiviral targets.
  Methods in molecular biology (Clifton, N.J.) 01/2011; 721:383-95.