This SuperSeries is composed of the SubSeries listed below.
CHOP induces activating transcription factor 5 (ATF5) to trigger apoptosis in response to perturbations in protein homeostasis.
Specimen part, Treatment
View SamplesEnvironmental stresses that disrupt protein homeostasis induce phosphorylation of eIF2, triggering repression of global protein synthesis coincident with preferential translation of ATF4, a transcriptional activator of the Integrated stress response (ISR). Depending on the extent of protein disruption, ATF4 may not be able to restore proteostatic control and instead switch to a terminal outcome that features elevated expression of the transcription factor CHOP (GADD153/DDIT3). The focus of this study was to define the mechanisms by which CHOP directs gene regulatory networks that determine cell fate. We find that in response to proteasome inhibition, CHOP induces the expression of a collection of genes encoding transcription regulators, including ATF5, which is preferentially translated during eIF2 phosphorylation. Transcriptional expression of ATF5 is directly activated by both CHOP and ATF4. Knock-down of ATF5 increased cell survival in response to proteasome inhibition, supporting the idea that both ATF5 and CHOP have pro-apoptotic functions. Transcriptome analyses of ATF5-dependent genes revealed targets involved in apoptosis, including, NOXA, which is important for inducing cell death during proteasome inhibition. This study suggests that the ISR features a feed-forward loop of stress induced transcriptional regulators, each subject to transcriptional and translational control that can switch cell fate towards apoptosis.
CHOP induces activating transcription factor 5 (ATF5) to trigger apoptosis in response to perturbations in protein homeostasis.
Specimen part, Treatment
View SamplesDisruptions of the endoplasmic reticulum (ER) that perturb protein folding cause ER stress and elicit an unfolded protein response (UPR) that involves translational and transcriptional changes in gene expression aimed at expanding the ER processing capacity and alleviating cellular injury. Three ER stress sensors PERK, ATF6, and IRE1 implement the UPR. PERK phosphorylation of eIF2 during ER stress represses protein synthesis, which prevents further influx of ER client proteins, along with preferential translation of ATF4, a transcription activator of the integrated stress response. In this study we show that the PERK/eIF2~P/ATF4 pathway is required not only for translational control, but also activation of ATF6 and its target genes. The PERK pathway facilitates both the synthesis of ATF6 and trafficking of ATF6 from the ER to the Golgi for intramembrane proteolysis and activation of ATF6. As a consequence, liver-specific depletion of PERK significantly reduces both the translational and transcriptional phases of the UPR, leading to reduced protein chaperone expression, disruptions of lipid metabolism, and enhanced apoptosis. These findings show that the regulatory networks of the UPR are fully integrated, and helps explain the diverse pathologies associated with loss of PERK.
The eIF2 kinase PERK and the integrated stress response facilitate activation of ATF6 during endoplasmic reticulum stress.
Specimen part, Treatment
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 SamplesIdentification of all genes expressed by mouse olfactory sensory neurons; genes expressed in mature neurons, immature neurons, or both were distinguished. Independent validation of enrichment ratio values supported by statistical assessment of error rates was used to build a database of statistical probabilities of the expression of all mRNAs detected in mature neurons, immature neurons, both types of neurons (shared), and the residual population of all other cell types.
Genomics of mature and immature olfactory sensory neurons.
Sex, Specimen part
View SamplesCardiac disease accounts for the largest proportion of adult mortality and morbidity in the industrialized world. However, progress toward improved clinical treatments is hampered by an incomplete understanding of the genetic programs controlling early cardiogenesis. To better understand this process, we set out to identify genes whose expression is enriched within early cardiac fated populations, obtaining the transcriptional signatures of mouse embryonic stem cells (mESCs) differentiating along a cardiac path.
Efficient array-based identification of novel cardiac genes through differentiation of mouse ESCs.
No sample metadata fields
View SamplesThis SuperSeries is composed of the SubSeries listed below.
The Gene Expression Barcode: leveraging public data repositories to begin cataloging the human and murine transcriptomes.
Treatment
View SamplesWe hybridized yeast RNA to the mouse 430 2.0 array to estimate the background binding for each probe.
The Gene Expression Barcode: leveraging public data repositories to begin cataloging the human and murine transcriptomes.
Treatment
View SamplesMouse embryonic stem cells can differentiate in vitro into spontaneously contracting cardiomyocytes. The main objective of this study was to investigate cardiogenesis in cultures of differentiating embryonic stem cells (ESCs) and to determine how closely it mimics in vivo cardiac development. We identified and isolated a population of cardiac progenitor cells (CPCs) through the use of a reporter DNA construct that allowed the expression of a selectable marker under the control of the Nkx2.5 enhancer. We proceeded to characterize these CPCs by examining their capacity to differentiate into cardiomyocytes and to proliferate. We then performed a large-scale temporal microarray expression analysis in order to identify genes that are uniquely upregulated or downregulated in the CPC population. We determined that the transcriptional profile of the mESC derived CPCs was consistent with pathways known to be active during embryonic cardiac development. We conclude that in vitro differentiation of mESCs recapitulates the early steps of mouse cardiac development.
Mouse ES cell-derived cardiac precursor cells are multipotent and facilitate identification of novel cardiac genes.
No sample metadata fields
View SamplesThe aim of this study is to profile gene expression dynamics during the in vitro differentiation of embryonic stem cells into ventral motor neurons. Expression levels were profiled using Affymetrix microarrays at six timepoints during in vitro differentiation: ES cells (Day 0), embryoid bodies (Day 2), retinoid induction of neurogenesis (Day 2 +8hours of exposure to retinoic acid), neural precursors (Day 3), progenitor motor neurons (Day 4), postmitotic motor neurons (Day 7).
Ligand-dependent dynamics of retinoic acid receptor binding during early neurogenesis.
Cell line
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