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Divergent transcriptomic responses to aryl hydrocarbon receptor agonists between rat and human primary hepatocytes.
Sex, Age, Specimen part
View Samples(Abstract) Toxicogenomics has great potential for enhancing our understanding of environmental chemical toxicity, hopefully leading to better-informed human health risk assessments. This study employed toxicogenomic technology to reveal species differences in response to two prototypical aryl hydrocarbon receptor (AHR) agonists, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and the polychlorinated biphenyl (PCB) congener PCB 126. Dose responses of primary cultures of rat and human hepatocytes were determined using species-specific microarrays sharing over 4,000 gene orthologs. Forty-seven human and 79 rat genes satisfied dose response criteria for both chemicals and were subjected to further analysis including the calculation of EC50 and the relative potency (REP) of PCB 126 for each gene. Only 5 responsive orthologous genes were shared between the two species, yet the geometric mean of the REPs for all rat and human modeled responsive genes were 0.06 (95% Confidence Interval (CI); 0.03-0.1) and 0.002 (95% CI; 0.001-0.005), respectively, suggesting broad species differences in the initial events that follow AHR activation but precede toxicity. This indicates that there are species differences in both the specific genes that responded and the agonist potency and relative potency for those genes. This observed insensitivity of human cells to PCB 126 is consistent with more traditional measurements of AHR activation (i.e., CYP1A1 enzyme activity) and suggests that the species difference in PCB 126 sensitivity is likely due to certain aspects of AHR function. That a species divergence also exists in this expanded AHR-regulated gene repertoire is a novel finding and should help when extrapolating animal data to humans.
Divergent transcriptomic responses to aryl hydrocarbon receptor agonists between rat and human primary hepatocytes.
Sex, Age, Specimen part
View SamplesChronic exposure of Sprague-Dawley (SD) rats to either 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or Aroclor 1254 results in female-selective induction of hepatic tumors. The relative potency of dioxins and PCB mixtures, such as Aroclor 1254, is often estimated using the internationally endorsed toxic equivalency (TEQ) approach. Comparing the genome wide changes in gene expression in both genders following exposure to toxic equivalent doses of these chemicals should identify critical sets of early response genes while further defining the concept of the TEQ of halogenated aromatic hydrocarbons. Aroclor 1254 at 0.6, 6.0 and 60 mg/kg body weight and TEQ doses of TCDD (0.3 and 3.0 g/kg), calculated to match the top two Aroclor 1254 doses, were orally administered to SD rats for three consecutive days. Day 4 gene expression in hepatic tissue was determined using microarrays. A linear mixed-effects statistical model was developed to analyze the data in relation to treatment, gender, and gender*treatment (G*T) interactions. The genes most changed included 54 genes with and 51 genes without a significant model G*T term. The known aryl hydrocarbon receptor (AHR) battery genes (Cyp1a1, Cyp1a2, Cyp1b1, Aldh3a1), and novel genes, responded in a TEQ dose-dependent manner in both genders. However, an important observation was the apparent disruption of sexually dimorphic basal gene expression, particularly for female rats. Since many of these genes are involved in steroid metabolism, exposure to either TCDD or Aroclor 1254 could disrupt proliferative signals more in female rats as a possible consequence of altered estrogen metabolism. This study extends the findings of previous rodent bioassays by identifying groups of genes, other than the well-characterized AHR response genes, whose disruption may be important in the tumorigenic mechanism in this rat strain.
Toxicogenomic analysis of gender, chemical, and dose effects in livers of TCDD- or aroclor 1254-exposed rats using a multifactor linear model.
Sex
View SamplesOvarian cancer is one of the most deadly cancers accounting for only 3% of diagnosed cancers, but is the fifth leading cause of cancer deaths among woman; however, the progression of ovarian cancer is poorly understood. To study and further understand the early events that lead to epithelial derived ovarian cancer, we previously developed a cell model of progressive ovarian cancer. Mouse ovarian surface epithelial (MOSE) cells have undergone spontaneous transformation in cell culture and represent pre-neoplastic, non-tumorigenic to an aggressive malignant phenotype.
Changes in gene expression and cellular architecture in an ovarian cancer progression model.
Specimen part
View SamplesAn efficient innate immune recognition of the intracellular parasite T. cruzi is crucial for host protection against development of Chagas disease, which often leads to multiple organ damage, particularly the heart leading to cardiomyopathy. Mechanisms modulated by MyD88 have been shown to be necessary for resistance against T, cruzi infection. Recently, Nod-like receptors have been shown to play an important role as innate immune sensors, particularly as they relate to inflammasome function, caspase activation, and inflammatory cytokine production. In this study, we aimed to investigate the participation of innate immune responses in general, and inflammasomes in particular, in heart inflammation and cardiac damage upon infection with the T. cruzi parasite.
Apoptosis-associated speck-like protein containing a caspase recruitment domain inflammasomes mediate IL-1β response and host resistance to Trypanosoma cruzi infection.
Specimen part
View SamplesDifferentiation of naïve CD4+ T cells into effector (Th1, Th2 and Th17) and induced regulatory (iTreg) T cells requires lineage-specifying transcription factors and epigenetic modifications that allow appropriate repression or activation of gene transcription. The epigenetic silencing of cytokine genes is associated with the repressive H3K27 trimethylation mark, mediated by Ezh2 or Ezh1 methyltransferase components of the polycomb repressive complex 2 (PRC2). EZH2 over-expression and activating mutations are implicated in tumorigenesis and correlate with poor prognosis in several tumor types 35. This spurred the development of EZH2 inhibitors which, by inducing tumor cell growth arrest and cell death, show therapeutic promise in cancer. A role for Ezh2 in suppressing Th1 and Th2 cytokine production and survival has recently been reported. It is not entirely clear whether Ezh2-PRC2 plays a role in H3K27me3 in cytokine loci in naïve CD4+ T cells and whether H3K27me3 has a non-redundant role in T helper cell lineage differentiation and survival. Here, we investigate the effects of T cell-specific Ezh2 deletion to determine the role that Ezh2-PRC2 plays in regulating the fate of differentiating naïve CD4+ T cells. Loss of Ezh2 altered the expression of 1328 genes in Th0 and 1979 genes in iTreg cells. Gene expression changes were positively correlated in both cell types, indicating that Ezh2 targets similar genes in these cells. As expected, Ifng was one of the genes most increased in expression by following loss of Ezh2. In addition, expression of Tbx21 homolog Eomes, a transcription factor that regulates IFNG production, was also significantly increased. We then performed H3K27me3 ChIP-seq on Ezh2fl/fl and Ezh2fl/fl.CD4Cre Th0 cells. Consistent with cellular phenotype and RNA-seq data, we observed a loss of the H3K27me3 at Eomes, Il4 and Il10 loci . Very low levels of H3K27me3 marks were present at Ifng and Tbx21 loci in differentiated Ezh2fl/fl Th0 cells, suggesting that upon differentiation, upregulation or activation of transcription factors accounts for IFNG overproduction. A significant loss of H3K27me3 was observed >2kb upstream of Gata3 locus , however this did not result in increased transcription . Of the 22381 genes tested for changes in H3K27me3, 1360 showed a statistically significant decrease in Ezh2fl/fl.CD4Cre Th0 cells, compared to wildtype. Furthermore, 404 of these genes also showed a concomitant gain in expression in Ezh2fl/fl.CD4Cre Th0 cells, suggesting that these loci are likely direct Ezh2-PRC2 targets. Overall design: There are 3 biological replicates each of Ezh2fl/fl.CD4Cre and Ezh2fl/fl in both Th0 and iTreg cells for the RNA-seq experiment. There are 2 biological replicates each of Ezh2fl/fl.CD4Cre and Ezh2fl/fl in Th0 cells for the ChIP-seq experiment.
The polycomb repressive complex 2 governs life and death of peripheral T cells.
No sample metadata fields
View SamplesRNAseq analysis of BAFF in vitro-stimulated (6 hours) murine nfkb2fl/flCD19-Cre (furtheron designated as REL) and CD19-Cre (furtheron designated as WT) splenic B cells identifies genes regulated by the transcription factor NF-kB2 in BAFF-stimulated B cells. Overall design: Splenic B cells from 12-week old relfl/flCD19-Cre and CD19-Cre littermate mice were isolated by magnetic cell separation from splenic mononuclear cells and stimulated in vitro for 6 hours with BAFF. RNA was isolated and submitted for RNA-sequencing on an Illumina HiSeq2000 instrument for 30 million single-ended reads.
Impairment of Mature B Cell Maintenance upon Combined Deletion of the Alternative NF-κB Transcription Factors RELB and NF-κB2 in B Cells.
Specimen part, Treatment, Subject
View SamplesRNAseq analysis of CD40 in vitro-stimulated (6 hours) murine nfkb2fl/flCD19-Cre (furtheron designated as REL) and CD19-Cre (furtheron designated as WT) splenic B cells identifies genes regulated by the transcription factor NF-kB2 in activated B cells. Overall design: Splenic B cells from 12-week old relfl/flCD19-Cre and CD19-Cre littermate mice were isolated by magnetic cell separation from splenic mononuclear cells and stimulated in vitro for 6 hours with anti-CD40 and anti-IgM. RNA was isolated and submitted for RNA-sequencing on an Illumina HiSeq2000 instrument for 30 million single-ended reads.
Impairment of Mature B Cell Maintenance upon Combined Deletion of the Alternative NF-κB Transcription Factors RELB and NF-κB2 in B Cells.
Specimen part, Treatment, Subject
View SamplesLarge-scale genomic profiling efforts have facilitated the characterization of molecular alterations in cancers and aided the development of targeted kinase inhibitors for a wide array of cancer types. However, resistance to these targeted therapies invariably develops and limits their clinical efficacy. Targeting tumours with kinase inhibitors induces complex adaptive survival programs that promote the persistence of a fraction of the original cancer cell population, facilitating the eventual outgrowth of inhibitor-resistant tumour clones following clonal evolution. Here we show that the addition of a newly identified transcriptional repressor, THZ1, to targeted cancer therapy enhances cell killing and impedes the emergence of drug-resistant cell populations in cellular and in vivo cancer models with diverse genetic dependencies. We propose that targeted therapy induces a state of transcriptional dependency in a subpopulation of cells poised to become drug tolerant. THZ1 can exploit this dependency by blocking dynamic transcriptional responses, remodelling of enhancers and key signalling outputs required for tumour cell survival in the setting of targeted cancer therapies. These findings suggest that the addition of THZ1 to targeted cancer therapies is a promising broad-based strategy to hinder the emergence of drug-resistant cancer cell populations. Overall design: RNA-seq in tumor cell lines treated with targeted therapies and/or transcriptional inhibitors
Suppression of Adaptive Responses to Targeted Cancer Therapy by Transcriptional Repression.
Specimen part, Cell line, Subject, Compound
View SamplesRNA-seq analysis of murine eGFP+ relbfl/flnfkb2fl/flCg1-Cre and Cg1-Cre splenic germinal center B cells identifies genes regulated by the transcription factors RELB and p52 (NF-kB2) in germinal center B cells. Overall design: Germinal center B cells from 12-week old relbfl/flnfkb2fl/flCg1-Cre and Cg1-Cre littermate mice immunized with sheep red blood cells (SRBC) were isolated at day 7 after immunization by flow cytometric sorting from splenic mononuclear cells. RNA was isolated, amplified and submitted for RNA-sequencing on an Illumina HiSeq2500 instrument for 35-40 million 2x50 paired-ended reads.
Transcription factors of the alternative NF-κB pathway are required for germinal center B-cell development.
Age, Specimen part, Subject
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