Activity-dependent gene expression is central for sculpting neuronal connectivity in the brain. Despite the importance for synaptic plasticity, a comprehensive analysis of the temporal changes in the transcriptomic response to neuronal activity is lacking. In a genome wide survey we identified genes that were induced at 1, 4, 8, or 24 hours following neuronal activity in the hippocampus.
Genome-wide profiling of the activity-dependent hippocampal transcriptome.
Sex, Age, Specimen part, Time
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An immediate-late gene expression module decodes ERK signal duration.
Specimen part, Cell line
View SamplesWe integrate experimental data and mathematical modelling to unveil how ERK signal duration is relayed to mRNA dynamics.
An immediate-late gene expression module decodes ERK signal duration.
Cell line
View SamplesUnderstanding how regulatory sequences interact in the context of chromosomal architecture is a central challenge in biology. Chromosome conformation capture revealed that mammalian chromosomes possess a rich hierarchy of structural layers, from multi-megabase compartments to sub-megabase topologically associating domains (TADs), and further down to sub-TAD loop domains. TADs appear to act as regulatory microenvironments by constraining and segregating regulatory interactions across discrete chromosomal regions. However, it is unclear whether other (or all) folding layers share similar properties, or rather TADs constitute a privileged folding scale with maximal impact on the organization of regulatory interactions. Here we present a novel parameter-free algorithm (CaTCH) that identifies hierarchical trees of chromosomal domains in Hi-C maps, stratified through their reciprocal physical insulation which is a simple and biologically relevant property. By applying CaTCH to published Hi-C datasets, we show that previously reported folding layers appear at different insulation levels. We demonstrate that although no structurally privileged folding level exists, TADs emerge as a functionally privileged scale defined by maximal enrichment of CTCF at boundaries, and maximal cell-type conservation. By measuring transcriptional output in embryonic stem cells and neural precursor cells, we show that TADs also maximize the likelihood that genes in a domain are co-regulated during differentiation. Finally, we observe that regulatory sequences occur at genomic locations corresponding to optimized mutual interactions at the scale of TADs. Our analysis thus suggests that the architectural functionality of TADs arises from the interplay between their ability to partition interactions and the genomic position of regulatory sequences. Overall design: The hybrid mouse ESC line F1-21.6 (129Sv-Cast/EiJ), previously described in (Jonkers et al., 2009), were grown on mitomycin C-inactivated MEFs in ES cell media containing 15% FBS (Gibco), 10-4 M b-mercaptoethanol (Sigma), and 1000U/ml of leukaemia inhibitory factor (LIF, Chemicon). Mouse ES cells were differentiated into neural progenitor cells (NPC) as previously described (Conti et al., 2005; Splinter et al., 2011). Total RNAs were prepared by Trizol extraction from the mouse ESC line, and for one NPC clone derived from it. Two biological replicates were collected for ESCs and NPCs. After ribosomal RNA depletion with Ribo-Zero (Illumina), RNA-seq libraries were prepared using ScriptSeq v2 kit (Illumina) following the manufacturer’s instructions. Libraries were prepared in two technical replicates per biological replicate. 50 bp single-end sequencing was performed on Illumina HiSeq 2000 instruments according to manufacturer’s instructions.
Reciprocal insulation analysis of Hi-C data shows that TADs represent a functionally but not structurally privileged scale in the hierarchical folding of chromosomes.
Specimen part, Subject
View SamplesAberrant cell signaling can cause cancer and other diseases and is a focal point of drug research. A common approach is to infer signaling activity of pathways from gene expression. However, mapping gene expression to pathway components disregards the effect of post-translational modifications, and downstream signatures represent very specific experimental conditions. Here we present PROGENy, a method that overcomes both limitations by leveraging a large compendium of publicly available perturbation experiments to yield a common core of Pathway RespOnsive GENes. Unlike existing methods, PROGENy can (i) recover the effect of known driver mutations, (ii) provide or improve strong markers for drug indications, and (iii) distinguish between oncogenic and tumor suppressor pathways for patient survival. Collectively, these results show that PROGENy accurately infers pathway activity from gene expression. Overall design: HEK293?RAF1:ER cells were treated with different stimuli (4OHT, Ly29002, TNFa, TGF1b, IFNg) for different periods of time (1h, 4h).
Perturbation-response genes reveal signaling footprints in cancer gene expression.
Specimen part, Subject
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Reverse engineering a hierarchical regulatory network downstream of oncogenic KRAS.
Cell line, Treatment
View SamplesRAS mutations are highly relevant for progression and therapy response of human tumours, but the genetic network that ultimately executes the oncogenic effects is poorly understood. Here we used a reverse-engineering approach in an ovarian cancer model to reconstruct KRAS oncogene-dependent cytoplasmic and transcriptional networks from perturbation experiments based on gene silencing and pathway inhibitor treatments. We measured mRNA and protein levels in manipulated cells by microarray, RT-PCR and Western Blot analysis, respectively. The reconstructed model revealed complex interactions among the transcriptional and cytoplasmic components, some of which were confirmed by double pertubation experiments. Interestingly, the transcription factors decomposed into two hierarchically arranged groups. To validate the model predictions we analysed growth parameters and transcriptional deregulation in the KRAS-transformed epithelial cells. As predicted by the model, we found two functional groups among the selected transcription factors. The experiments thus confirmed the predicted hierarchical transcription factor regulation and showed that the hierarchy manifests itself in downstream gene expression patterns and phenotype.
Reverse engineering a hierarchical regulatory network downstream of oncogenic KRAS.
Cell line, Treatment
View SamplesRAS mutations are highly relevant for progression and therapy response of human tumours, but the genetic network that ultimately executes the oncogenic effects is poorly understood. Here we used a reverse-engineering approach in an ovarian cancer model to reconstruct KRAS oncogene-dependent cytoplasmic and transcriptional networks from perturbation experiments based on gene silencing and pathway inhibitor treatments. We measured mRNA and protein levels in manipulated cells by microarray, RT-PCR and Western Blot analysis, respectively. The reconstructed model revealed complex interactions among the transcriptional and cytoplasmic components, some of which were confirmed by double pertubation experiments. Interestingly, the transcription factors decomposed into two hierarchically arranged groups. To validate the model predictions we analysed growth parameters and transcriptional deregulation in the KRAS-transformed epithelial cells. As predicted by the model, we found two functional groups among the selected transcription factors. The experiments thus confirmed the predicted hierarchical transcription factor regulation and showed that the hierarchy manifests itself in downstream gene expression patterns and phenotype.
Reverse engineering a hierarchical regulatory network downstream of oncogenic KRAS.
Cell line, Treatment
View SamplesGoals of the study was to compare transcripional and phenotypic response of mouse intestinal organoid cultures to the PIK3CA(H1047R) and CTNNB1(stab) oncogenes. Overall design: Two biological replicates of organoids with transgenic tdTomato-Luciferase, tdTomato-PIK3CAH1047R, tdTomato-CTNNB1stab or td-Tomato-PIK3CAH1047R-CTNNB1stab were analysed by RNA-Seq By comparing 7-10 x 10E7 50bp paired end reads per library we identify transcriptional alterations in the intestinal epithelium following expression of each or both oncogenes,
Oncogenic β-catenin and PIK3CA instruct network states and cancer phenotypes in intestinal organoids.
Specimen part, Cell line, Subject
View SamplesSafety sciences and the identification chemical hazard have been seen as one of the most immediate practical applications of human pluripotent stem cell technology. Protocols for the generation of many desirable human cell types have been developed, but optimization of neuronal models for toxicological use has been astonishingly slow, and the wide, clinically- important field of peripheral neurotoxicity is still largely unexplored. Here, a 2-step protocol to generate large lots of identical peripheral human neuronal precursors was characterized and adapted to the measurement of peripheral neurotoxicity. High content imaging allowed an unbiased assessment of cell morphology and viability. The computational quantification of neurite growth as functional parameter highly sensitive to disturbances by toxicants was used as endpoint reflecting specific neurotoxicity. The differentiation of cells towards dorsal root ganglia neurons was tracked in relation to a large background data set based on gene expression microarrays. On this basis, a peripheral neurotoxicity (PeriTox) test was developed as first toxicological assay that harnesses the potential of human pluripotent stem cells to generate cell types/tissues that are not otherwise available for prediction of human systemic organ toxicity. Testing of more than 30 chemicals showed that human neurotoxicants, as well as neurite growth enhancers, were correctly identified. Various classes of chemotherapeutics causing human peripheral neuropathies were identified, while they were missed when tested on human central neurons. The PeriTox-test established here shows the potential of human stem cells for clinically-relevant safety testing of drugs in use and of new emerging candidates.
Stem Cell-Derived Immature Human Dorsal Root Ganglia Neurons to Identify Peripheral Neurotoxicants.
Sex, Specimen part, Cell line
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