The thymus is extremely sensitive to damage but also has a remarkable ability to repair itself. However, the mechanisms underlying this endogenous regeneration remain poorly understood and this capacity diminishes considerably with age. To identify alternate regeneration pathways in the thymus, we performed an unbiased transcriptome analysis of the non-hematopoietic (CD45-) stromal cell compartment of the thymus, which is less sensitive to thymic damage compared to the CD45+ hematopoietic compartment.
Production of BMP4 by endothelial cells is crucial for endogenous thymic regeneration.
Sex, Specimen part
View SamplesOur laboratory wanted to define the transcription profile of aged skeletal muscle. For this reason, we performed a triplicate microarray study on young (3 weeks) and aged (24 months) gatrocnemius muscle from wild-type C57B16 Mice
Transcriptional profiling of skeletal muscle reveals factors that are necessary to maintain satellite cell integrity during ageing.
Sex
View SamplesThe objective of this set of samples is to identify genes that are differentially expressed following the introduction of DNA double strand breaks (DSBs) by ionizing radiation in wild-type murine pre-B cells. The data generated in this project will be compared to the data generated in GSE9024, in which genes that are differentially expressed following the introduction of DNA double strand breaks (DSBs) by the Rag proteins in murine pre-B cells were examined. In order to understand the differences between the physiologic and genotoxic responses to DSB DNA damage, we need to compare cells that are all in the same compartment of the cell cycle. We are therefore examining the response to IR-induced damage in cells that are arrested in G1, which would correspond to our previous study of G1 arrested cells with Rag-induced breaks. This will illuminate the difference directly, allowing us to better understand the signaling responses to the different types of DNA damage.
DNA damage activates a complex transcriptional response in murine lymphocytes that includes both physiological and cancer-predisposition programs.
Specimen part
View SamplesAstrogliosis is a hallmark of the response to brain ischemia, comprised of changes in gene expression and morphology. Hsp72 protects from cerebral ischemia, and although several mechanisms of protection have been investigated, effects on astrocyte activation are unknown. To identify potential mechanisms of protection, gene expression was assessed in mice subjected to middle cerebral artery (MCAO) or sham surgery, of either wildtype (WT) or Hsp72-overexpressing (Hsp72Tg) mice. After stroke, both genotypes exhibited genes related to cell death, stress response, and immune response. Furthermore, genes indicative of astrocyte activation, including cytoskeletal proteins and cytokines, were upregulated. To measure astrocyte activation after stroke, detailed histological and morphological analyses were performed in the cortical penumbra after stroke using unbiased stereology. Consistent with other reports, we observed a marked and persistent increase in glial fibrillary acidic protein (GFAP ) as soon as 3 hours after MCAO. In contrast, vimentin immunoreactivity appeared 12-24 hours after stroke, peaked at 72 hours, and returned to baseline after 30 days. Surprisingly, no change in overall astrocyte number was observed based on glutamine synthetase (GS) immunoreactivity. To determine if Hsp72Tg mice exhibited altered astrocyte activation compared to WT controls, morphological evaluation by fractal analysis was used. Overexpression of Hsp72 reduced astrocyte cell area, arbor area, and to a lesser extent fractal dimension, 72 hours following stroke. In conclusion, in vivo overexpression of Hsp72 alters gene expression following stroke, including genes involved in astrocyte activation, and decreases astrocyte activation acutely following MCAO. Thus, modulation of astrogliosis may be a neuroprotective mechanism exerted by Hsp72 after ischemia.
Effects of heat shock protein 72 (Hsp72) on evolution of astrocyte activation following stroke in the mouse.
Sex, Treatment
View SamplesGlud1 (glutamate dehydrogenase 1) transgenic mice release more excitatory neurotransmitter glutamate to synaptic cleft throughout lifespan and show signs of accelerated aging.
Transcriptomic responses in mouse brain exposed to chronic excess of the neurotransmitter glutamate.
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View SamplesThis SuperSeries is composed of the SubSeries listed below.
Developmentally regulated higher-order chromatin interactions orchestrate B cell fate commitment.
Specimen part
View SamplesOrganization of the genome in 3D nuclear-space is known to play a crucial role in regulation of gene expression. However, the chromatin architecture that impinges on the B cell-fate choice of multi-potent progenitors remains unclear. By employing in situ Hi-C, we have identified distinct sets of genomic loci that undergo a developmental switch between permissive and repressive compartments during B-cell fate commitment. Intriguingly, we show that topologically associating domains (TADs) represent co-regulated subunits of chromatin and display considerable structural alterations as a result of changes in the cis-regulatory interaction landscape. The extensive rewiring of cis-regulatory interactions is closely associated with differential gene expression programs. Further, we demonstrate the regulatory role of Ebf1 and its downstream factor, Pax5, in chromatin reorganization and transcription regulation. Together, our studies reveal that alterations in promoter and cis-regulatory interactions underlie changes in higher-order chromatin architecture, which in turn determines cell-identity and cell-type specific gene expression patterns.
Developmentally regulated higher-order chromatin interactions orchestrate B cell fate commitment.
Specimen part
View SamplesDisruption of protein folding in the endoplasmic reticulum triggers the Unfolded Protein Response (UPR), a transcriptional and translational control network designed to restore protein homeostasis. Central to the UPR is PERK phosphorylation of the alpha subunit of eIF2 (eIF2~P), which represses global translation coincident with preferential translation of mRNAs, such as ATF4 and CHOP, that serve to implement the UPR transcriptional regulation. In this study, we used sucrose gradient ultracentrifugation and a genome-wide microarray approach to measure changes in mRNA translation during ER stress. Our analysis suggests that translational efficiencies vary across a broad range during ER stress, with the majority of transcripts being either repressed or resistant to eIF2~P, while a notable cohort of key regulators are subject to preferential translation. From this latter group, we identify IBTKa as being subject to both translation and transcriptional induction during eIF2~P in both cell lines and a mouse model of ER stress. Translational regulation of IBTKalpha mRNA involves the stress-induced relief of two inhibitory uORFs in the 5'-leader of the transcript. Depletion of IBTKalpha by shRNA reduced viability of cultured cells coincident with increased caspase 3/7 cleavage, suggesting that IBTKalpha is a key regulator in determining cell fate during the UPR.
Selective mRNA translation during eIF2 phosphorylation induces expression of IBTKα.
Specimen part
View SamplesThe satellite cell of skeletal muscle provides a paradigm for quiescent and activated tissue stem cell states. We have carried out transcriptome analyses by comparing satellite cells from adult skeletal muscles, where they are mainly quiescent, with cells from growing muscles, regenerating (mdx) muscles, or with cells in culture, where they are activated. Our study gives new insights into the satellite cell biology during activation and in respect with its niche.
An adult tissue-specific stem cell in its niche: a gene profiling analysis of in vivo quiescent and activated muscle satellite cells.
Specimen part
View SamplesThese data are from the brains (amygdala and hippocampus) of mice originally derived from a cross between C57BL/6J and DBA/2J inbred strains. We used short-term selection to produce outbred mouse lines with differences in contextual fear conditioning, which is a measure of fear learning. We selected for a total of 4 generations. Fear learning differed in the selected lines and this difference was stronger with each successive generation of selection. These mice also showed differences for measures of anxiety-like behavior, but were not different for tests of non-fear motivated learning, suggesting that selection altered alleles that are specifically involved in emotional behaviors. We identified several QTLs for the selection response. We used Affymetrix microarrays to identify differentially expressed genes in the amygdala and hippocampus of mice from the final generation of selection. Amygdala and hippocampus samples were rapidly dissected out of experimentally nave mice f rom each selected line. Three samples were pooled and hybridized to each array. Experimentally nave mice were used because the behavior of the mice can be reliably anticipated due to their lineage. Thus, these gene expression differences are not due to the response to human handling, foot shock or fear-inducing conditioned stimuli. We have a second similar study that focuses on a different selected population that was based on C57BL/6J and A/J mice (see GES4034).
Selection for contextual fear conditioning affects anxiety-like behaviors and gene expression.
No sample metadata fields
View Samples