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  • 2018  (6)
  • Salmonella
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  • 2018  (6)
  • 1
    Language: English
    In: Science (New York, N.Y.), 07 December 2018, Vol.362(6419), pp.1156-1160
    Description: Many bacterial infections are hard to treat and tend to relapse, possibly due to the presence of antibiotic-tolerant persisters. In vitro, persister cells appear to be dormant. After uptake of species by macrophages, nongrowing persisters also occur, but their physiological state is poorly understood. In this work, we show that persisters arising during macrophage infection maintain a metabolically active state. Persisters reprogram macrophages by means of effectors secreted by the pathogenicity island 2 type 3 secretion system. These effectors dampened proinflammatory innate immune responses and induced anti-inflammatory macrophage polarization. Such reprogramming allowed nongrowing cells to survive for extended periods in their host. Persisters undermining host immune defenses might confer an advantage to the pathogen during relapse once antibiotic pressure is relieved.
    Keywords: Drug Resistance, Bacterial ; Host-Pathogen Interactions -- Immunology ; Macrophages -- Immunology ; Salmonella Infections -- Drug Therapy ; Salmonella Typhimurium -- Metabolism ; Type III Secretion Systems -- Metabolism
    ISSN: 00368075
    E-ISSN: 1095-9203
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  • 2
    In: EMBO Journal, 02 July 2018, Vol.37(13), pp.n/a-n/a
    Description: Long non‐coding s (lncs) play important roles in many cellular pathways, but their contribution to the defense of eukaryotic cells against pathogens remains poorly understood. A new study from Imamura in reports that infection in human cells impacts nuclear decay, which in turn drives the accumulation of otherwise unstable nuclear lncs, some of which may have protective effects against this common bacterial pathogen. These unexpected findings demand more efforts to fully decrypt the molecular functions of lncs in innate and adaptive immunity. infection impairs the nuclear RNA decay machinery in human cells, increasing the abundance of long non‐coding RNAs with a role in innate immunity.
    Keywords: Pathogens ; Immunity ; Infections ; Pathogens ; Molecular Chains ; Salmonella ; Bacterial Infections ; Pathogens ; Ribonucleic Acid–RNA ; Ribonucleic Acid–RNA ; Adaptive Immunity;
    ISSN: 0261-4189
    E-ISSN: 1460-2075
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  • 3
    In: EMBO Journal, 03 December 2018, Vol.37(23), pp.n/a-n/a
    Description: While mucosal inflammation is a major source of stress during enteropathogen infection, it remains to be fully elucidated how the host benefits from this environment to clear the pathogen. Here, we show that host stress induced by different stimuli mimicking inflammatory conditions strongly reduces the binding of to epithelial cells. Mechanistically, stress activates acid sphingomyelinase leading to host membrane remodeling. Consequently, knockdown or pharmacological inhibition of the acid sphingomyelinase blunts the stress‐dependent inhibition of binding to host cells. Interestingly, stress caused by intracellular replication also results in remodeling of the host cell membrane, and , which precludes re‐infection by this and other non‐motile pathogens. In contrast, Typhimurium overcomes the shortage of permissive entry sites by gathering effectively at the remaining platforms through its flagellar motility. Overall, our findings reveal host membrane remodeling as a novel stress‐responsive cell‐autonomous defense mechanism that protects epithelial cells from infection by non‐motile bacterial pathogens. Stress‐induced host membrane remodeling constitutes a novel cell‐autonomous defensive mechanism that protects epithelial cells from infection by and other non‐motile bacterial pathogens. Host oxidative stress strongly reduces S. flexneri binding to epithelial cells. Stress leads to host membrane remodeling, via activation of the acid sphingomyelinase by the MAPK p38 pathway, resulting in the formation of ceramide domains. Intracellular Shigella replication induces remodeling of the host cell membrane, in vitro and in vivo. Stress‐induced host membrane remodeling precludes re‐infection by non‐motile pathogens; motile pathogens are able to overcome this barrier through flagellar motility. Host membrane remodeling is a cell‐autonomous defense mechanism that protects epithelial cells from infection by .
    Keywords: Acid Sphingomyelinase ; Host Stress Response ; Membrane Remodeling ; Salmonella ; Shigella
    ISSN: 0261-4189
    E-ISSN: 1460-2075
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  • 4
    Language: English
    In: Methods in molecular biology (Clifton, N.J.), 2018, Vol.1737, pp.59-75
    Description: Transcriptomics, i.e., the quantification of cellular RNA transcripts, is a powerful way to gauge the physiological state of either bacterial or eukaryotic cells under a given condition. However, traditional approaches were unsuitable to measure the abundance of transcripts across kingdoms, which is relevant for biological processes such as bacterial infections of mammalian host cells. This changed with the establishment of "Dual RNA-seq," which profiles gene expression simultaneously in an infecting bacterium and its infected host. Here, we describe a detailed Dual RNA-seq protocol optimized for-but not restricted to-the study of human cell culture models infected with the Gram-negative model pathogen Salmonella Typhimurium. Furthermore, we provide experimental data demonstrating the benefits of some of the key steps of this protocol, including transcriptome stabilization (RNA fixation), FACS-based enrichment of invaded cells, and double rRNA depletion. While our focus is on data generation, we also include a section describing suitable computational methods to analyze the obtained datasets.
    Keywords: Cell Sorting ; Dual RNA-Seq ; Fixation ; Host-Pathogen Interaction ; Infection ; Noncoding RNA ; RNA-Seq ; Salmonella ; Transcriptomics ; Rrna Depletion ; Gene Expression Profiling ; Host-Pathogen Interactions ; Computational Biology -- Methods ; High-Throughput Nucleotide Sequencing -- Methods ; Salmonella Infections -- Microbiology ; Salmonella Typhimurium -- Genetics ; Sequence Analysis, RNA -- Methods
    E-ISSN: 1940-6029
    Source: MEDLINE/PubMed (U.S. National Library of Medicine)
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  • 5
    Language: English
    In: https://doi.org/10.1371/journal.pgen.1007401
    Description: Invasion of epithelial cells by Salmonella enterica requires expression of genes located in the pathogenicity island I (SPI-1). The expression of SPI-1 genes is very tightly regulated and activated only under specific conditions. Most studies have focused on the regulatory pathways that induce SPI-1 expression. Here, we describe a new regulatory circuit involving CRP-cAMP, a widely established metabolic regulator, in silencing of SPI-1 genes under non-permissive conditions. In CRP-cAMP-deficient strains we detected a strong upregulation of SPI-1 genes in the mid-logarithmic growth phase. Genetic analyses revealed that CRP-cAMP modulates the level of HilD, the master regulator of Salmonella invasion. This regulation occurs at the post-transcriptional level and requires the presence of a newly identified regulatory motif within the hilD 3'UTR. We further demonstrate that in Salmonella the Hfq-dependent sRNA Spot 42 is under the transcriptional repression of CRP-cAMP and, when this transcriptional repression is relieved, Spot 42 exerts a positive effect on hilD expression. In vivo and in vitro assays indicate that Spot 42 targets, through its unstructured region III, the 3'UTR of the hilD transcript. Together, our results highlight the biological relevance of the hilD 3'UTR as a hub for post-transcriptional control of Salmonella invasion gene expression.
    Keywords: Salmonel·La ; Expressió Gènica ; Salmonella ; Gene Expression
    ISSN: 1553-7390
    Source: Universitat de Barcelona
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  • 6
    Language: English
    In: PLoS Genetics, 01 June 2018, Vol.14(6), p.e1007401
    Description: Invasion of epithelial cells by Salmonella enterica requires expression of genes located in the pathogenicity island I (SPI-1). The expression of SPI-1 genes is very tightly regulated and activated only under specific conditions. Most studies have focused on the regulatory pathways that induce SPI-1 expression. Here, we describe a new regulatory circuit involving CRP-cAMP, a widely established metabolic regulator, in silencing of SPI-1 genes under non-permissive conditions. In CRP-cAMP-deficient strains we detected a strong upregulation of SPI-1 genes in the mid-logarithmic growth phase. Genetic analyses revealed that CRP-cAMP modulates the level of HilD, the master regulator of Salmonella invasion. This regulation occurs at the post-transcriptional level and requires the presence of a newly identified regulatory motif within the hilD 3'UTR. We further demonstrate that in Salmonella the Hfq-dependent sRNA Spot 42 is under the transcriptional repression of CRP-cAMP and, when this transcriptional repression is relieved, Spot 42 exerts a positive effect on hilD expression. In vivo and in vitro assays indicate that Spot 42 targets, through its unstructured region III, the 3'UTR of the hilD transcript. Together, our results highlight the biological relevance of the hilD 3'UTR as a hub for post-transcriptional control of Salmonella invasion gene expression.
    Keywords: Biology
    ISSN: 1553-7390
    E-ISSN: 1553-7404
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