Background: Global DNA methylation contributes to genomic integrity by supressing repeat associated transposition events. Several chromatin factors are required in addition to DNA methyltransferases to maintain DNA methylation at intergenic and satellite repeats. Embryos lacking Lsh, a member of the SNF2 superfamily of chromatin helicases, are hypomethylated. The interaction of Lsh with the de novo methyltransferase, Dnmt3b, facilitates the deposition of DNA methylation at stem cell genes. We wished to determine if a similar targeting mechanism operates to maintain DNA methylation at repetitive sequences. Results: We used HELP-seq to map genome wide DNA methylation patterns in Lsh-/- and Dnmt3b-/- somatic cells. DNA methylation is predominantly lost from specific genomic repeats in Lsh-/- cells: LTR-retrotransposons, LINE-1 repeats and mouse satellites. RNA-seq experiments demonstrate that specific IAP (Intracisternal A-type particle) LTRs and satellites, but not LINE-1 elements, are aberrantly transcribed inLsh-/- cells. LTR hypomethylation in Dnmt3b-/- cells is moderate and hypomethylated repetitive elements (IAP, LINE-1 and satellite) are silent. Chromatin immunoprecipitation (ChIP) indicates that repressed LINE-1 elements gain H3K4me3, but H3K9me3 levels are unaltered in Lsh-/- cells, indicating that DNA hypomethylation alone is not permissive for their transcriptional activation. Mis-expressed IAPs and satellites lose H3K9me3 and gain H3K4me3 in Lsh-/- cells. Conclusions: Our study emphasizes that regulation of repetitive elements by DNA methylation is selective and context dependent. We propose a model where Lsh is specifically required at a precise developmental window to target de novo methylation to repeat sequences, which is subsequently maintained by Dnmt1 in somatic cells to enforce repeat silencing thus contributing to genomic integrity. Overall design: Two pairs of RNA samples compared: WT and Lsh-/- RNA isolations from tail-tip fibroblasts; WT and Lsh-/- RNA isolations from E13.5 mouse embryos.
Lsh regulates LTR retrotransposon repression independently of Dnmt3b function.
No sample metadata fields
View SamplesExposure to high levels of arsenic in drinking water is associated with several types of cancers including lung, bladder and skin, as well as vascular disease and diabetes. Drinking water standards are based primarily on epidemiology and extrapolation from higher dose experiments, rather than measurements of phenotypic changes associated with chronic exposure to levels of arsenic similar to the current standard of 10ppb, and little is known about the difference between arsenic in food as opposed to arsenic in water. Measurement of phenotypic changes at low doses may be confounded by the effect of laboratory diet, in part because of trace amounts of arsenic in standard laboratory chows, but also because of broad metabolic changes in response to the chow itself. Finally, this series contrasts 8hr, 1mg/kg injected arsenic with the various chronic exposures, and also contrasts the acute effects of arsenic, dexamethasone or their combination. Male C57BL/6 mice were fed on two commercially available laboratory diets (LRD-5001 and AIN-76A) were chronically exposed, through drinking water or food, to environmentally relevant concentrations of sodium arsenite, or acutely exposed to dexamethasone.
Laboratory diet profoundly alters gene expression and confounds genomic analysis in mouse liver and lung.
No sample metadata fields
View SamplesExposure to high levels of arsenic in drinking water is associated with several types of cancers including lung, bladder and skin, as well as vascular disease and diabetes. Drinking water standards are based primarily on epidemiology and extrapolation from higher dose experiments, rather than measurements of phenotypic changes associated with chronic exposure to levels of arsenic similar to the current standard of 10ppb, and little is known about the difference between arsenic in food as opposed to arsenic in water. Measurement of phenotypic changes at low doses may be confounded by the effect of laboratory diet, in part because of trace amounts of arsenic in standard laboratory chows, but also because of broad metabolic changes in response to the chow itself. Finally, this series contrasts 8hr, 1mg/kg injected arsenic with the various chronic exposures, and also contrasts the acute effects of arsenic, dexamethasone or their combination. Male C57BL/6 mice were fed on two commercially available laboratory diets (LRD-5001 and AIN-76A) were chronically exposed, through drinking water or food, to environmentally relevant concentrations of sodium arsenite, or acutely exposed to dexamethasone.
Chronic exposure to arsenic in the drinking water alters the expression of immune response genes in mouse lung.
No sample metadata fields
View SamplesRelative levels of RNA transcripts were compared between anterior and posterior wing bud thirds from stage HH24 normal and talpid3 mutant chicken embryos using chicken Affymetrix chips. Data collected with Affymetrix scanner was normalized using the Plier algorithm within the expression console package from Affymetrix and log2 transformed. 5 replicates of anterior third normal wing buds, 4 replicates of posterior third of normal wing buds and 4 replicates each of anterior and posterior thirds of talpid3 wing buds at stage HH24 were examined.
Identification of genes downstream of the Shh signalling in the developing chick wing and syn-expressed with Hoxd13 using microarray and 3D computational analysis.
Age, Specimen part
View SamplesH929 human myeloma cells were exposed to aminopeptidase inhibitor (CHR-2797), HDAC inhibitor (CHR-3996), or a combinaion of the two agents, for 24 hours.
The combination of HDAC and aminopeptidase inhibitors is highly synergistic in myeloma and leads to disruption of the NFκB signalling pathway.
Specimen part, Cell line, Treatment
View SamplesWe used microarrays to detect the primary changes caused by the 'san' mutation in Roquin gene by comparing the gene expression profiles of naive (CD44lo) CD8+ T cell population.
Breakdown in repression of IFN-γ mRNA leads to accumulation of self-reactive effector CD8+ T cells.
Specimen part
View SamplesStem cell fate is governed by the integration of intrinsic and extrinsic positive and negative signals upon inherent transcriptional networks. To identify novel embryonic stem cell (ESC) regulators and assemble transcriptional networks controlling ESC fate, we performed temporal expression microarray analyses of ESCs following the initiation of commitment and integrated these data with known genome-wide transcription factor binding. Effects of forced under- or over-expression of predicted novel regulators, defined as differentially expressed genes with potential binding sites for known regulators of pluripotency, demonstrated greater than 90% correspondence with predicted function, as assessed by functional and high content assays of self-renewal. We next assembled 43 theoretical transcriptional networks in ESCs, 82% (23 out of 28 tested) of which were supported by analysis of genome-wide expression in Oct4 knockdown cells. By using this integrative approach we have, for the first time, formulated novel networks describing gene repression of key developmental regulators in undifferentiated ESCs and successfully predicted the outcomes of genetic manipulation of these networks.
Prediction and testing of novel transcriptional networks regulating embryonic stem cell self-renewal and commitment.
No sample metadata fields
View SamplesRNA-Seq analysis was performed to define the associated changes in gene expression of skeletal muscle treated with follistatin Overall design: Skeletal muscle mRNA profiles from follistatin and control treated tibialis anterior muscles. Acute (3 day treatment, 3 control and 4 follistatin replicates) and chronic (7or 14 day treatment, 3 control and 4 follistatin replicates) timepoints were analysed.
Integrated expression analysis of muscle hypertrophy identifies <i>Asb2</i> as a negative regulator of muscle mass.
Specimen part, Cell line, Treatment, Subject
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Interferon-γ Inhibits Ebola Virus Infection.
Specimen part
View SamplesEpisodic Ebola virus (EBOV) outbreaks, such as the current one in West Africa, emphasize the critical need for novel antivirals against this highly pathogenic virus. Here, we demonstrate that interferon gamma (IFN) prevents morbidity and mortality associated with EBOV infection when administered to mice either 24 hours prior to or 2 hours following EBOV infection. Microarray studies with IFN-stimulated human macrophages identified novel interferon-stimulated genes (ISGs) that inhibit EBOV infection upon ectopic expression. IFN treatment reduced viral RNA levels in macrophages to a similar degree as cells treated with the protein synthesis inhibitor, cycloheximide, suggesting that IFN treatment inhibits genome replication. As IFN treatment robustly protects mice against EBOV infection, we propose that this FDA-approved drug may serve as a useful prophylactic or therapeutic strategy during EBOV outbreaks, contributing to the currently limited arsenal of filovirus antivirals.
Interferon-γ Inhibits Ebola Virus Infection.
Specimen part
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