The inflammatory response initiated by microbial products signaling through Toll-like receptors (TLRs) of the innate immune system is essential for host defense against infection. Because inflammation can be harmful to host tissues, the innate response is highly regulated. Negative regulation of TLR4, the receptor for bacterial lipopolysaccharide (LPS), results in LPS tolerance, defined as hyporesponsiveness to repeated stimulation with LPS. LPS tolerance is thought to protect the host from excessive inflammation by turning off TLR4 signal, which then shuts down TLR-induced genes. However, TLR signaling induces hundreds of genes with very different functions. We reasoned that genes with different functions should have different requirements for regulation. Specifically, genes encoding proinflammatory mediators should be transiently inactivated to limit tissue damage, while genes encoding antimicrobial effectors, which directly target pathogens, should remain inducible in tolerant cells to protect the host from infection. Using an in vitro system of LPS tolerance in macrophages, here we show that TLR-induced genes may indeed be divided into two distinct categories based on their functions and regulatory requirements. Further, we show these distinct groups are regulated by gene-specific, and not signal-specific mechanisms.
Gene-specific control of inflammation by TLR-induced chromatin modifications.
Specimen part
View SamplesToll like receptor 4 (TLR4), an innate immunity gene, is involved in responses to several pulmonary agonists including endotoxin (LPS; Poltorak et al.,1998), ozone (O3 ,Kleeberger et. al., 2001), Pseudomonas aeruginosa (Faure et al, 2004), and hyperoxia (Zhang et al, 2005). TLR4 appears to partially mediate the response to LPS- and O3-induced lung injury, however, TLR4 is protective for prevention of injury in Pseudomonas aeruginosa infection and against acute lung injury (hyperoxia). The mechanism behind this protection is unclear. We previously demonstrated that TLR4 was also protective against BHT-induced chronic inflammation and tumor promotion (Bauer et al, 2005). C.C3H-Tlr4Lps-d (BALBLps-d) mice, congenic for a 10 cM region of C3H/HeJ chromosome 4 that contains Tlr4 (Vogel et al, 1994), have a missence mutation that renders TLR4 dysfunctional. The Tlr4 mutation likely abrogates signaling by disrupting a direct point of contact with other signaling molecules (Akira S, Takeda K. Toll-like receptor signalling. Nat Rev Immunol 2004;4(7):499-511.). Bronchoalveolar lavage fluid (BALF) alveolar macrophages, lymphocytes, and total protein content were significantly elevated in BALBLps-d mice compared to BALB/c (BALB; Tlr4 sufficient) mice following chronic BHT (Bauer et al., 2005). BALBLps-d mice also had a significant increase in tumor multiplicity (60%) over that of BALB mice in response to an MCA/BHT tumor promotion protocol. While this was the first model to demonstrate a protective role for TLR4 in chronic lung inflammation and tumorigenesis, the downstream mechanism regulating this protective response remains unknown. Using Affymetrix microarray analysis followed by GeneSpring and Ingenuity pathway analyses, we herein identified known and novel downstream pathways and their interactions that may be involved in the protective mechanism elicited by TLR4. We therefore hypothesize that these pathways and interactions amongst the genes identified during the tumor promotion/chronic inflammation stage are in part influencing the differential strain response observed during tumorigenesis.
Transcriptomic analysis of pathways regulated by toll-like receptor 4 in a murine model of chronic pulmonary inflammation and carcinogenesis.
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View SamplesBackground: The mechanisms underlying ozone (O3)-induced pulmonary inflammation remain unclear. Interleukin (IL)-10 is an anti-inflammatory cytokine that is known to inhibit inflammatory mediators.
Protective role of interleukin-10 in ozone-induced pulmonary inflammation.
Sex, Specimen part
View SamplesBackground: Cancer stem cells are presumed to have virtually unlimited proliferative and self-renewal abilities and to be highly resistant to chemotherapy, a feature that is associated with overexpression of ATP-binding cassette transporters. We investigated whether prolonged continuous selection of cells for drug resistance enriches cultures for cancer stem-like cells.
Prolonged drug selection of breast cancer cells and enrichment of cancer stem cell characteristics.
Cell line, Treatment
View SamplesThis study focused on transcription in the medial PFC (mPFC) as a function of age and cognition. Young and aged F344 rats were characterized on tasks, attentional set shift and spatial memory, which depend on the mPFC and hippocampus, respectively. Differences in transcription associated with age and cognitive function were examined using RNA sequencing to construct transcriptomic profiles for the mPFC, white matter, and region CA1 of the hippocampus. The results indicate regional differences in vulnerability to aging associated with increased expression of immune and defense response genes and a decline in synaptic and neural activity genes. Importantly, we provide evidence for region specific transcription related to behavior. In particular, expression of transcriptional regulators and neural activity-related immediate-early genes (IEGs) are increased in the mPFC of aged animals that exhibit delayed set shift behavior; relative to age-matched animals that exhibit set shift behavior similar to younger animals. Overall design: The study contains 11 young and 20 aged rats for the mPFC and CA1 samples, which were used to investigate expression patterns associated with aging and behavior. White matter samples were used to investigate an age-related effect with 8 young and 9 aged rats.
Transcription Profile of Aging and Cognition-Related Genes in the Medial Prefrontal Cortex.
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View SamplesAging is associated with a decline in hippocampal mediated learning and memory, a process wich can be ameliorated by dietary (caloric) restriction. We used Affymetrix gene expression analysis to monitor changes in three regions of the hippocampus (CA1, CA3, DG) of middle aged (18 months) and old (28 month) rats that were exposed to dietary restriction. Old rats were determined to be good performers (GP) or poor performers (PP) in behavioral tests to assess thier hippocampal function.
Gene expression in the hippocampus: regionally specific effects of aging and caloric restriction.
Age, Specimen part
View SamplesFuran is a mouse and rat hepatocarcinogen. We sought to determine if furan-induced gene expression changes could be detected in paired fresh-frozen and formalin-fixed paraffin embedded (FFPE) samples using RNA-seq (polyA-enrichment protocol). All samples in this study (fresh-frozen, 18 hours in formalin, 3 weeks in formalin) were also examined using one- and two-colour microarrays and RNA-seq (ribo-depletion protocol) in order to determine the effect of the technology on gene expression profiles. Overall design: In this study we examined the transcriptional response in liver tissue of female B6C3F1 mice exposed to furan for 3 weeks to 8 mg/kg bw furan (or vehicle control) and sacrificed four hours after the final exposure. Each dose group had 4 biological replicates. There were a total of 24 samples included in the final analysis of the polyA enrichment RNA-seq experiment.
Mining the Archives: A Cross-Platform Analysis of Gene Expression Profiles in Archival Formalin-Fixed Paraffin-Embedded Tissues.
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View SamplesCell body and pseudopod RNA are differentially regulated during the migration of the metastatic cancer cells.We wanted to identify the RNA which are upregulated in the pseudopodial (PS) fraction as compared to cell body fraction (CB).
Pseudopodial actin dynamics control epithelial-mesenchymal transition in metastatic cancer cells.
Cell line
View SamplesThe Atss3 mutant and WT plants were arranged according to a Randomized Complete Block Design. The plants were planted in rows with seven rows in each flat; two plants of the same genotype/pot. Plants were grown under a SD photoperiod (8 h light/16 h dark) in a growth chamber as described. Eight randomly selected rows were harvested for each time point from different flats. Plant material was harvested at five time points in the diurnal cycle (1, 4, 8.5, 12, and 16 h; Time 0 is the beginning of the light period); harvesting was conducted under a green safety light. Each sample consisted of rosette leaves (leaves 5 to 8, staged following Bowmann (1994); photosynthetically active (Stessman et al., 2002)) from sixteen six-week-old plants. Leaf samples were frozen in liquid N2 immediately after harvest and stored at -80C for RNA extraction. The experiment was done twice and independent randomizations for plant growth and harvest were used for the two replicates.
Identification of the novel protein QQS as a component of the starch metabolic network in Arabidopsis leaves.
No sample metadata fields
View SamplesLeukotriene E4 (LTE4) the most stable of the cysteinyl leukotrienes (cysLTs) binds poorly to classical type 1 (CysLT1) and 2 (CysLT2) receptors although it induces potent responses in human airways in vivo, such as bronchoconstriction, airway hyperresponsiveness and inflammatory cell influx suggesting the presence of a novel receptor that preferentially responds to LTE4. To identify such a receptor two human mast cell lines, LAD2 and LUVA, were selected that differentially responded to LTE4 when analysed by intracellular signalling and gene expression. Comparative transcriptome analysis and recombinant gene overexpression experiments revealed CysLT1 as a receptor responsible for potent LTE4-induced response in LAD2 but not in LUVA cells, an observation confirmed further by gene knockdown and selective inhibitors. Lentiviral overexpression of CysLT1 in LUVA cells augmented intracellular calcium signalling induced by LTE4 but did not restore full agonist responses at the gene expression level. Our data support a model where both an increased expression of Gq-coupled CysLT1, and sustained intracellular calcium mobilisation and extracellular signal-regulated kinase (Erk) activation, are required for LTE4-mediated regulation of gene expression in human cells. Our study shows for the first time that CysLT1 expression is critically important for responsiveness to LTE4 within a human cell system.
Leukotriene E4 is a full functional agonist for human cysteinyl leukotriene type 1 receptor-dependent gene expression.
Cell line
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