Project description:We investigated the interaction of Salmonella Typhimurium with Embryonic stem cell derived Dendritic Cells (ESDCs) as a new model to study host-pathogen interaction.
Project description:the aim of the study was to assess the role of flagellin in the interaction bwetween Salmonella Typhi and host cells. A macrophage-like cell line (THP1) and an epithelial cell line (Hep2) were infected with S. Typhi expressing one of three flagellin variants: Hd, Hj or Hz66. A non-flagellated mutant (DfliC) and a non-invasive mutant (DinvA) were used as controls
Project description:Raghunathan2009 - Genome-scale metabolic
network of Salmonella typhimurium (iRR1083)
This model is described in the article:
Constraint-based analysis of
metabolic capacity of Salmonella typhimurium during
host-pathogen interaction.
Raghunathan A, Reed J, Shin S,
Palsson B, Daefler S.
BMC Syst Biol 2009; 3: 38
Abstract:
BACKGROUND: Infections with Salmonella cause significant
morbidity and mortality worldwide. Replication of Salmonella
typhimurium inside its host cell is a model system for studying
the pathogenesis of intracellular bacterial infections.
Genome-scale modeling of bacterial metabolic networks provides
a powerful tool to identify and analyze pathways required for
successful intracellular replication during host-pathogen
interaction. RESULTS: We have developed and validated a
genome-scale metabolic network of Salmonella typhimurium LT2
(iRR1083). This model accounts for 1,083 genes that encode
proteins catalyzing 1,087 unique metabolic and transport
reactions in the bacterium. We employed flux balance analysis
and in silico gene essentiality analysis to investigate growth
under a wide range of conditions that mimic in vitro and host
cell environments. Gene expression profiling of S. typhimurium
isolated from macrophage cell lines was used to constrain the
model to predict metabolic pathways that are likely to be
operational during infection. CONCLUSION: Our analysis suggests
that there is a robust minimal set of metabolic pathways that
is required for successful replication of Salmonella inside the
host cell. This model also serves as platform for the
integration of high-throughput data. Its computational power
allows identification of networked metabolic pathways and
generation of hypotheses about metabolism during infection,
which might be used for the rational design of novel
antibiotics or vaccine strains.
This model is hosted on
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and identified by:
MODEL1507180058.
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To the extent possible under law, all copyright and related or
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Project description:Small RNAs play a critical role in host-pathogen interaction and microRNAs have emerged as key regulators of viral infections. Based on this evidence, we wished to contribute to this research field by identifying and characterizing cellular microRNAs with a positive or negative role on Sindbis virus (SINV) infection.
Project description:Salmonella enterica Serovar Typhimurium (S. Typhimurium) causes enterocolitis in humans and calves characterized by diarrhea and polymorphonuclear cell (PMN) influx to the intestinal mucosa. The Salmonella Type III Secretion System encoded at Pathogenicity Island I (SPI-1) translocates the Salmonella effector proteins SipA, SopA, SopB, SopD, and SopE2 into the host epithelial cell cytoplasm. These five effector proteins act in concert to induce fluid secretion and transcription of C-X-C chemokines, which serve to recruit PMNs to the intestine. While the individual molecular interactions of these Salmonella proteins with cultured host cells have been extensively characterized, their combined role in the generation of fluid secretion and inflammation is less well understood. A bovine ligated ileal loop model was used in conjunction with a custom bovine microarray to determine intestinal response to acute S. Typhimurium infection in the calf. Gene expression responses to both wild type S. Typhimurium a delta sipA, sopABDE2 mutant were measured at seven times during the initial 12 hours of infection. Microarray analysis confirmed increased expression of genes encoding proteins previously associated with immune response to Salmonella spp. infection. Gene expression changes were mapped to molecular interaction pathways and changes in expression of mechanistic genes, which are defined as perturbed genes identified by Bayesian genetic network modeling, were strongly involved in the mechanisms of the host immune response. In addition to correctly identifying known effects of wild type S. Typhimurium on host (bovine) gene expression, Bayesian genetic network modeling identified novel effects of S. Typhimurium on several molecular interaction pathways. Novel effects impacted gene regulation in the following pathways: adipocytokine signaling, insulin signaling, complement and coagulation cascades, axon guidance, gap junction, neuroactive ligand-receptor interaction, long-term depression, long-term potentiation, melanogenesis, and natural killer cell mediated cytotoxicity. Known effects were observed in the following pathways: regulation of actin cytoskeleton, apoptosis, cytokine-cytokine receptor interaction, cell adhesion molecules (CAMs), MAPK signaling, calcium signaling, Jak-STAT signaling, leukocyte transendothelial migration, adherens junction, tight junction, and ECM-receptor interactions, phosphatidylinositol signaling system, and antigen processing and presentation. Quantitative real-time PCR was used to verify the expression of some of these mechanistic genes. Microarrays were used to examine the transcriptional profiles of bovine intestinal epithelia infected with wild type Salmonella enterica serotype Typhimurium (control and wild type or delta sipA sopABDE2 mutant infected) across seven time points (15 min, 30 min, 1, 2, 4, 8, and 12 hours). Experiments were performed in quadruplicate (bovine ligated ileal loops surgeries were performed with four calves), generateing a total of 84 arrays.
Project description:microRNA dysregulation is a common feature of cancer cells, but the complex roles of microRNAs in cancer are not fully elucidated. Here we used functional genomics to identify oncogenic microRNAs in non-small cell lung cancer and to evaluate their impact on response to EGFR targeting therapy. Our data demonstrate that microRNAs with an AAGUGC-motif in their seed-sequence increase both cancer cell proliferation and sensitivity to EGFR inhibitors. Global transcriptomics, proteomics and target prediction resulted in the identification of several tumor suppressors involved in the G1/S transition as targets of AAGUGC-microRNAs. The clinical implications of our findings were evaluated by analysis of public domain data supporting the link between this microRNA seed-family, their tumor suppressor targets and cancer cell proliferation. In conclusion we propose that AAGUGC-microRNAs are an integral part of an oncogenic signaling network, and that these findings have potential therapeutic implications, especially in selecting patients for EGFR-targeting therapy.
Project description:Salmonella-related infections outcome are dependent on the complex interaction between environmental factors, bacterial serotype and host genetic factors. Using ENU chemical mutagenesis, we identified a pedigree named Immunity to Typhimurium 14 (Ity14) carrying a mutation in Stat4 (c.1335+5G>A). Here we used a recognized experimental model of systemic Salmonella Typhimurium infection in mice to study the impact of Stat4 mutation on typhoid-like disease. We compare whole-genome transcriptional profiles between wild-type and Ity14 mutant mice to identify common or unique gene expression profiles between these groups.
Project description:Subversion of the host cytoskeleton is a critical virulence mechanism used by a variety of intracellular bacterial pathogens during their infectious life cycles. Growing evidence suggests that the tactics employed by pathogens are surprisingly diverse. Using proteomic and biochemical methods, we demonstrate that the S. Tm type III effector protein SopB potently interacts specifically with host cell IFs vimentin. After host cell entry, Salmonella replicates in Salmonella containing vacuoles (SCVs), which accumulate a dense meshwork of vimentin through the Salmonella SPI-1 type III secretion effector SopB. We also demonstrate an important role for SopB-vimentin interaction, in the cellular responses including pro-inflammatory cytokine production induced by Salmonella. Vimentin interacts with the N-terminus of the S. Tm T3SS effector protein SopB. Vimentin and its interaction with SopB are dispensable for S. Tm invasion, but are required for stable formation of SCVs which are essential for bacteria replication. Moreover, SopB lacking of N-terminus cdc42-binding domain loses the interaction with vimentin, suggesting that the small GTPase is critical in SopB triggered vimentin recruitment to form integrative SCVs. These findings establish that SCVs integrity of the bacterium specifically requires intermediate filaments vimentin, which is a prerequisite for highly efficient S. Tm replication.
Project description:Salmonella enterica Serovar Typhimurium (S. Typhimurium) causes enterocolitis in humans and calves characterized by diarrhea and polymorphonuclear cell (PMN) influx to the intestinal mucosa. The Salmonella Type III Secretion System encoded at Pathogenicity Island I (SPI-1) translocates the Salmonella effector proteins SipA, SopA, SopB, SopD, and SopE2 into the host epithelial cell cytoplasm. These five effector proteins act in concert to induce fluid secretion and transcription of C-X-C chemokines, which serve to recruit PMNs to the intestine. While the individual molecular interactions of these Salmonella proteins with cultured host cells have been extensively characterized, their combined role in the generation of fluid secretion and inflammation is less well understood. A bovine ligated ileal loop model was used in conjunction with a custom bovine microarray to determine intestinal response to acute S. Typhimurium infection in the calf. Gene expression responses to both wild type S. Typhimurium a delta sipA, sopABDE2 mutant were measured at seven times during the initial 12 hours of infection. Microarray analysis confirmed increased expression of genes encoding proteins previously associated with immune response to Salmonella spp. infection. Gene expression changes were mapped to molecular interaction pathways and changes in expression of mechanistic genes, which are defined as perturbed genes identified by Bayesian genetic network modeling, were strongly involved in the mechanisms of the host immune response. In addition to correctly identifying known effects of wild type S. Typhimurium on host (bovine) gene expression, Bayesian genetic network modeling identified novel effects of S. Typhimurium on several molecular interaction pathways. Novel effects impacted gene regulation in the following pathways: adipocytokine signaling, insulin signaling, complement and coagulation cascades, axon guidance, gap junction, neuroactive ligand-receptor interaction, long-term depression, long-term potentiation, melanogenesis, and natural killer cell mediated cytotoxicity. Known effects were observed in the following pathways: regulation of actin cytoskeleton, apoptosis, cytokine-cytokine receptor interaction, cell adhesion molecules (CAMs), MAPK signaling, calcium signaling, Jak-STAT signaling, leukocyte transendothelial migration, adherens junction, tight junction, and ECM-receptor interactions, phosphatidylinositol signaling system, and antigen processing and presentation. Quantitative real-time PCR was used to verify the expression of some of these mechanistic genes.
Project description:The flagellum provides essential motility in the pathogenic process of Salmonella host invasion. However, flagellin is strongly antigenic and can be recognized by TLR5, resulting in activation of the host immune system to clear the invading pathogen. The presence of flagella also disrupts the integrity of the bacterial cytosol, making it more vulnerable to external adversities. Salmonella must rapidly shut down the flagella synthesis system after entering the host cell to evade the host immune system and resist damage from external adverse factors. Our studies showed YdiV(STM1344) play a key role in regulating the transcription of flagella-related genes during Salmonella invasion. After the ydiV(stm1344) gene was knocked out, the pathogenicity of Salmonella was significantly reduced. Here, we performed a TMT-based comparative quantitative proteomics analysis to reveal the proteomic differences between the WT and △ydiV(stm1344) in simulated host environment medium.