Our laboratory has recently discovered that E. coli cells starved for the DNA precursor dGTP are killed efficiently (dGTP starvation) in a manner similar to that described for Thymineless Death (TLD). Conditions for specific dGTP starvation can be achieved by depriving an E. coli optA1 gpt strain of the purine nucleotide precursor hypoxanthine (Hx). To gain insight into the mechanisms underlying dGTP starvation, we conducted genome-wide gene expression analyses on actively growing optA1 gpt strains subjected to hypoxanthine deprivation for increasing periods of time. The data show that, upon Hx withdrawal, the optA1 gpt strain displays a diminished ability to de-repress the de novo purine biosynthesis genes, and this is likely due to internal guanine accumulation. The impairment to fully induce the purR regulon may be a contributing factor to the lethality of dGTP starvation. At later time points, and coinciding with cell lethality, strong induction of the SOS is observed, supporting the concept of replication stress as a final cause of death. No evidence was observed for the participation of other stress responses, including the rpoS-mediated global stress response in the starved cells, and reinforcing the lack of feedback of replication stress into the global metabolism of the cell. The genome-wide expression data also provide direct evidence for increased genome complexity during dGTP starvation, as a markedly increased gradient is observed for expression of genes located nearby the replication origin relative to those located towards the replication terminus.
Transcriptome Analysis of Escherichia coli during dGTP Starvation.
No sample metadata fields
View SamplesMicroRNA-520f regulates EMT, as it activates CDH1 (mRNA) and E-cadherin (protein) expression, and it suppresses tumor cell invasion. We have characterized miR-520f target genes through whole genome transcriptional profiling of miRNA transfected pancreas cancer cells (PANC-1).
miRNA-520f Reverses Epithelial-to-Mesenchymal Transition by Targeting <i>ADAM9</i> and <i>TGFBR2</i>.
Cell line, Treatment
View SamplesThe PAR-domain basic leucine zipper (PAR bZip) transcription factors DBP, TEF, and HLF accumulate in a highly circadian manner in several peripheral tissues, including liver and kidney. Mice devoid of all three of these proteins are born at expected Mendelian ratios, but are epilepsy-prone, age at an accelerated rate and die prematurely. In the hope of identifying PAR bZip target genes whose altered expression might contribute to the high morbidity and mortality of PAR bZip triple knockout mice, we compared the liver and kidney transcriptomes of these animals to those of wild-type or heterozygous mutant mice. These experiments revealed that PAR bZip proteins control the expression of many enzymes and regulators involved in detoxification and drug metabolism, such as cytochrome P450 enzymes, carboxylesterases, and constitutive androstane receptor (CAR). Indeed, PAR bZip triple knockout mice are hypersensitive to xenobiotic compounds, and the deficiency in detoxification may contribute to their early ageing.
The circadian PAR-domain basic leucine zipper transcription factors DBP, TEF, and HLF modulate basal and inducible xenobiotic detoxification.
Sex, Specimen part, Time
View SamplesGENES ASSOCIATED WITH THE CELL CYCLE, LINEAGE COMMITMENT AND IMMUNOMODULATORY POTENTIAL DISCRIMINATE HUMAN POSTNATAL STEM CELLS OF DIFFERENT ORIGIN.
Functional differences between mesenchymal stem cell populations are reflected by their transcriptome.
No sample metadata fields
View SamplesThe current test strategy for carcinogenicity is generally based on in vitro and in vivo genotoxicity assays. Non-genotoxic carcinogens (NGTXC) are negative for genotoxicity and go undetected. Therefore, alternative tests to detect these chemicals are urgently needed. NGTXC act through different modes of action, which complicates the development of such assays. We have demonstrated recently in primary mouse hepatocytes that some, but certainly not all, NGTXC can be categorized according to their mode of action based on feature detection at a gene expression level (Schaap et al. 2012, PMID22710402). Identification of a wider range of chemicals probably requires multiple in vitro systems. In the current study we describe the added value of using mouse embryonic stem cells. In this study the focus is on NGTXC, but we also included genotoxic carcinogens and non-carcinogens. This approach enables us to assess the robustness of this method and to evaluate the system for recognizing features of chemicals in general, which is important for application in future risk assessment.
A novel toxicogenomics-based approach to categorize (non-)genotoxic carcinogens.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Integrative "-Omics" Analysis in Primary Human Hepatocytes Unravels Persistent Mechanisms of Cyclosporine A-Induced Cholestasis.
Specimen part, Treatment, Time
View SamplesCyclosporine A (CsA), is an endecapeptide with strong immunosuppressant activities and has contributed significantly towards clinical progress in organ transplantation. Furthermore, it has various toxic effects in the kidney and especially in the liver where it may induce cholestasis. The CsA drug-induced cholestasis (DIC) pathway includes important genes involved in the uptake, synthesis, conjugation and secretion of bile acids, which can be verified also in hepatic models in vitro. However, whether changes in CsA-induced cholestasis pathway induced in vitro are persistent thus presenting important biomarkers for repeated dose toxicity, has not yet been investigated. We therefore performed multiple -omics analyses, including whole genome analysis of DNA methylation, gene expression and microRNA expression in primary human hepatocytes (PHH) cultured in sandwich configuration, during and after terminating CsA treatment. For this, cells were exposed to a non-cytotoxic dose of 30 M CsA daily for 3 and 5 days. To investigate the persistence of induced changes upon terminating the CsA exposure of 5 days, a subset of PHH was subjected to a washout period (WO-period) of three days. DNA methylation (using NimbleGen 2.1 deluxe promoter arrays), transcriptomic (using Affymetrix Human Genome U133 Plus 2.0 arrays) and microRNA (using Agilent Sureprint G3 Unrestricted Human miRNA V16 8 60 K microarrays) analyses were performed on days 3, 5 and 8. Identification of differentially methylated genes (DMGs), differentially expressed genes (DEGs), and differentially expressed microRNAs (DE-miRs) was performed using several R packages. DMGs, DEGs and DE-miRs were found after CsA treatment of PHH for 3 and 5 days as well after the WO-period. Interestingly, 828 persistent DEGs and 6 persistent DE-miRs, but no persistent DMGs, were found after the WO-period. These persistent DEGs and DE-miRs showed concordance for 22 genes (13 genes upregulated in gene expression and downregulated in microRNA expression; 9 genes downregulated in gene expression and upregulated in microRNA expression). Some of the persistent transcriptomic changes as well as DE-miRs could be successfully mapped onto the DIC pathway, while epigenetic changes not. Furthermore, 29 persistent DEGs in vitro showed changes in the same direction as observed in livers from cholestasis patients. None of those 29 DEGs were present in the DIC pathway or cholestasis adverse outcome pathway. We have for the first time demonstrated a persistent impact of gene expression and microRNA expression related to DIC after repeated dose administration of CsA in vitro.
Integrative "-Omics" Analysis in Primary Human Hepatocytes Unravels Persistent Mechanisms of Cyclosporine A-Induced Cholestasis.
Specimen part, Treatment, Time
View SamplesStudies investigating the causes of autism spectrum disorder (ASD) point to genetic as well as epigenetic mechanisms of the disease. Identification of epigenetic processes that contribute to ASD development and progression is of major importance and may lead to the development of novel therapeutic strategies. Here we identify the bromodomain and extra-terminal domain containing transcriptional regulators (BETs) as epigenetic drivers of an ASD-like disorder in mice. We found that the pharmacological suppression of the BET proteins by a novel, highly selective and brain-permeable inhibitor, I-BET858, leads to selective suppression of neuronal gene expression followed by the development of an autism-like syndrome in mice. Many of the I-BET858 affected genes have been linked to ASD in humans thus suggesting the key role of the BET-controlled gene network in ASD. Our studies also suggest that environmental factors controlling BET proteins or their target genes may contribute to the epigenetic mechanism of ASD.
Autism-like syndrome is induced by pharmacological suppression of BET proteins in young mice.
Specimen part
View SamplesPurpose: Seek for differential gene expression in vemurafenib-resistant A375 tumors vs. untreated controls to provide a rationale for resistance mechanism Methods: mRNA profiles of vemurafenib-resistant A375 tumors and untreated control tumors were generated by transcriptome sequencing of A375 melanoma bearing mice. Since our xenograft samples contain a mixture of human and mouse RNAs we mapped RNASeq reads against a hybrid human/mouse genome. We than removed reads of potential mouse origin by taking only reads that map uniquely to human chromosomes. On average 23% of reads were removed as potential mouse reads. We than took the remaining reads (on average 77% per sample) to determine the gene expression levels for each sample. Normalized expression levels of 5 resistant samples were compared to 4 untreated control samples to detect differnetially regulated genes which may contribute to vemurfenib resistance Results: Expression levels of several genes were consistently altered in all resistant samples. Expression of e.g. genes encoding SPRY2, SPRY4, DUSP6, CCND1, PIK3R3, FGFR1, EPHA4, MCL1, and IGF1R was down-regulated, whereas expression of PDGFC, VEGFC, ABCB9 and KITLG was increased. Conclusions: Our study reports several differentially expressed genes which may contribute to vemurafenib resistance in A375 tumor bearing mice Overall design: RNA sequencing of genes expressed in A375 tumors bearing mice treated with vemurafenib until in vivo resistance appeared vs. untreated A375 tumors
A Novel RAF Kinase Inhibitor with DFG-Out-Binding Mode: High Efficacy in BRAF-Mutant Tumor Xenograft Models in the Absence of Normal Tissue Hyperproliferation.
No sample metadata fields
View SamplesEffects of Nipped-B and Rad21 sister chromatid cohesin proteins on gene expression data in ML-DmBG3 cells derived from Drosophila melanogaster larval central nervous system
Regulation of the Drosophila Enhancer of split and invected-engrailed gene complexes by sister chromatid cohesion proteins.
Time
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