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 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 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 SamplesP190B RhoGAP is required for mammary gland development, and its overexpression disrupts mammary gland branching morphogenesis. To better understand the mechanisms by which p190B regulates mammary gland development we performed gene expression microarray analysis on mammary epithelial cells isolated from p190B overexpressing transgenic mice compared to control mice.
No associated publication
Sex
View SamplesBackground: Preterm birth is the leading cause of all infant mortality. In 2004, 12.5% of all births were preterm. In order to understand preterm labor, we must first understand normal labor. Since many of the myometrial changes that occur during pregnancy are similar in mice and humans and mouse gestation is short, we have studied the uterine genes that change in the mouse during pregnancy. Here, we used microarray analysis to identify uterine genes in the gravid mouse that are differentially regulated in the cyclooxygenase-1 knockout mouse model of delayed parturition.
Identification of 9 uterine genes that are regulated during mouse pregnancy and exhibit abnormal levels in the cyclooxygenase-1 knockout mouse.
No sample metadata fields
View SamplesGerm free (GF) and conventionalized (CONV-D) wild-type C57Bl/6 male mice in the CARB-fed, 24h fasted, and 30d trained states; plus GF and CONV-D CARB-fed Ppara-/- mice. CARB-fed indicates a standard polysaccharide-rich mouse chow diet.
No associated publication
Sex, Specimen part
View SamplesSusceptible and Resistant mouse strain, e.g. DBA/2J and C57BL/6J respectively, were inoculated with a highly pathogenic H5N1 influenza A virus (A/Hong Kong/213/2003) for 72 hours.
Host genetic variation affects resistance to infection with a highly pathogenic H5N1 influenza A virus in mice.
Sex
View SamplesAnalysis of gene expression in lungs of C57BL/6J mice that develop chronic airway disease phenotypes after a single Sendai virus infection, compared with mice treated with UV-inactivated virus.
Persistent activation of an innate immune response translates respiratory viral infection into chronic lung disease.
Sex, Time
View SamplesHD R6/1 transgenic mouse line brain hemispheres dissected. RNA targets were created for transgenics and wildtypes at time points 18, 22 and 27 weeks. Profiles and data analysis performed using the Bioconductor software and linear model contrasts using LIMMA on RMA probeset summarys.
No associated publication
No sample metadata fields
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