Pseudomonas aeruginosa is an opportunistic pathogen that can adapt to changing environments and can secrete an exopolysaccharide known as alginate as a protection response resulting in a colony morphology and phenotype referred to as mucoid. However how P. aeruginosa senses its environment and activates alginate overproduction is not fully understood. Previously, we showed that Pseudomonas isolation agar (PIA) supplemented with ammonium metavanadate (PIAAMV) induces P. aeruginosa to overproduce alginate. Vanadate is a phosphate mimic and causes protein misfolding by disruption of disulfide bonds. Here we used PIAAMV to characterize the pathways involved in inducible alginate production and tested the global effects of P. aeruginosa growth on PIAAMV by a mutant library screen, transcriptomics, and in a murine acute virulence model. The PA14 non-redundant mutant library was screened on PIAAMV to identify new genes that are required for the inducible alginate stress response. A functionally diverse set of genes encoding products involved in cell envelope biogenesis, peptidoglycan, uptake of phosphate and iron, phenazines biosynthesis, and other processes were identified as positive regulators of the mucoid phenotype on PIAAMV. Transcriptome analysis of P. aeruginosa growing in the presence of vanadate caused differential expression of genes involved in virulence, envelope biogenesis, and cell stress pathways. In this study, it was observed that growth on PIAAMV attenuates P. aeruginosa in a mouse pneumonia model. Induction of alginate overproduction occurs as a stress response to protect P. aeruginosa but it may be possible to modulate and inhibit these pathways based on the new genes identified in this study.
Genes required for and effects of alginate overproduction induced by growth of Pseudomonas aeruginosa on Pseudomonas isolation agar supplemented with ammonium metavanadate.
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View SamplesThe Pseudomonas aeruginosa response regulator AlgR is critical for the organism's virulence and controls up to 155 different genes. In order to determine which genes are controlled by phosphorylated and unphosphorylated AlgR, phosphomimetic and phosphoablative alleles were recombined onto the chromosome of PAO1. The algR gene was mutated at aspartate 54 to asparagine (D54N) for the phosphoablative allele and mutated at aspartete 54 to glutamate (D54E) for the phosphomimetic allele. These alleles were recombined into the PAO1 chromosome.
<i>Pseudomonas aeruginosa</i> AlgR Phosphorylation Status Differentially Regulates Pyocyanin and Pyoverdine Production.
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View SamplesThe transcription factor STAT3 is constitutively activated in tumors of different origin but the molecular bases for STAT3 addiction of tumor cells have not yet been clearly identified. We generated knock/in mice carrying the constitutively active Stat3 allele, Stat3C, and showed that Stat3C could enhance Neu oncogenic power, triggering the production of earlier onset, more invasive mammary tumors. Tumor-derived cell lines displayed higher migration and invasion and disrupted distribution of cell-cell junction markers. The tensin family member Cten (C-Terminal Tensin-like), known to mediate EGF-induced migration and highly expressed in inflammatory breast cancer, was up-regulated in both Neu;Stat3C cells and tumors. Both Cten expression and enhanced migration were strictly dependent on Stat3, and Cten silencing normalized cell migration and rescued cell-cell contact defects. Importantly, the pro-inflammatory cytokine IL-6 could mediate Cten induction in MCF10 cells, in an exquisitely Stat3-dependent way. This model allowed us to shed some light on the oncogenic role of Stat3 in the breast, suggesting moreover a mechanism through which inflammatory signals can cooperate with EGF receptors in inflammatory breast cancer.
Constitutively active Stat3 enhances neu-mediated migration and metastasis in mammary tumors via upregulation of Cten.
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View SamplesWe used an inducible ShRNA system and microarrays to detail the global programme of gene expression underlying neuroblastoma differentiation upon CHAF1A silencing .
Histone chaperone CHAF1A inhibits differentiation and promotes aggressive neuroblastoma.
No sample metadata fields
View SamplesAnalysis of hepatic gene expression in mice transiently overexpressing Bcl2 Overall design: 3 control GFP mice and 5 GFP-Bcl2 mice, 8 mouse liver samples total
Bcl2 is a critical regulator of bile acid homeostasis by dictating Shp and lncRNA H19 function.
No sample metadata fields
View SamplesPre-mRNA splicing is functionally coupled to transcription, and genotoxic stresses can enhance alternative exon inclusion by affecting elongating RNA polymerase II. We report here that various genotoxic stress inducers, including camptothecin, inhibit the interaction between EWS, an RNA polymerase II-associated factor, and YB-1, a spliceosome-associated factor. This results in the cotranscriptional skipping of several exons of the MDM2 gene encoding the main p53 ubiquitin-ligase. This reversible exon skipping participates in the timely regulation of MDM2 expression, and may contribute to the accumulation of p53 during stress exposure and its rapid shut off when stress is removed. Finally, a splicing-sensitive microarray identified numerous exons that are skipped in response to camptothecin and EWS/YB-1 depletion. These data demonstrate genotoxic stress-induced alteration of the communication between the transcriptional and splicing machineries, resulting in widespread exon skipping and playing a central role in the genotoxic stress response.
Cotranscriptional exon skipping in the genotoxic stress response.
Specimen part, Cell line
View SamplesWe performed gene expression profiling of total RNA from brain samples derived from BSE-infected versus non-infected cynomolgus macaques (Macaca fascicularis).
Gene expression profiling of brains from bovine spongiform encephalopathy (BSE)-infected cynomolgus macaques.
Sex, Age, Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Molecular spectrum of BRAF, NRAS and KRAS gene mutations in plasma cell dyscrasias: implication for MEK-ERK pathway activation.
Specimen part, Cell line
View SamplesMultiple myeloma (MM) is a malignant disorder characterized by the clonal proliferation of plasma cells (PCs) in the bone marrow (BM). The genetic background and clinical course of the disease are largely heterogeneous, and MM pathophysiology ranges from the premalignant condition of monoclonal gammopathy of undetermined significance (MGUS) to smoldering MM, symptomatic MM, and extramedullary MM/plasma cell leukemia (PCL). Recent genome-wide sequencing efforts have provided the rationale for molecularly aimed treatment approaches, identifying mutations that can be specifically targeted, such as those in the mitogen-activated protein kinase (MAPK) pathway, which represent the most prevalent mutations in MM. Among these, mutations affecting BRAF gene, detected in 4-15% of patients, are of potential immediate clinical relevance due to the availability of effective inhibitors of this serine-threonine kinase which are in fact being explored also in myeloma.
Molecular spectrum of BRAF, NRAS and KRAS gene mutations in plasma cell dyscrasias: implication for MEK-ERK pathway activation.
Specimen part
View SamplesMultiple myeloma (MM) is a malignant disorder characterized by the clonal proliferation of plasma cells (PCs) in the bone marrow (BM). The genetic background and clinical course of the disease are largely heterogeneous, and MM pathophysiology ranges from the premalignant condition of monoclonal gammopathy of undetermined significance (MGUS) to smoldering MM, symptomatic MM, and extramedullary MM/plasma cell leukemia (PCL). Recent genome-wide sequencing efforts have provided the rationale for molecularly aimed treatment approaches, identifying mutations that can be specifically targeted, such as those in the mitogen-activated protein kinase (MAPK) pathway, which represent the most prevalent mutations in MM. Among these, mutations affecting BRAF gene, detected in 4-15% of patients, are of potential immediate clinical relevance due to the availability of effective inhibitors of this serine-threonine kinase which are in fact being explored also in myeloma.
Molecular spectrum of BRAF, NRAS and KRAS gene mutations in plasma cell dyscrasias: implication for MEK-ERK pathway activation.
Specimen part, Cell line
View Samples