Background: 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.
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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 SamplesThis SuperSeries is composed of the SubSeries listed below.
Exploiting microRNA and mRNA profiles generated in vitro from carcinogen-exposed primary mouse hepatocytes for predicting in vivo genotoxicity and carcinogenicity.
Specimen part, Compound
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Integrating factor analysis and a transgenic mouse model to reveal a peripheral blood predictor of breast tumors.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Experimentally derived metastasis gene expression profile predicts recurrence and death in patients with colon cancer.
Sex, Age, Disease stage, Race
View SamplesThe well-defined battery of in vitro systems applied within chemical cancer risk assessment is often characterised by a high false-positive rate, thus repeatedly failing to correctly predict the in vivo genotoxic and carcinogenic properties of test compounds. Toxicogenomics, i.e. mRNA-profiling, has been proven successful in improving the prediction of genotoxicity in vivo and the understanding of underlying mechanisms. Recently, microRNAs have been discovered as post-transcriptional regulators of mRNAs. It is thus hypothesised that using microRNA response-patterns may further improve current prediction methods. This study aimed at predicting genotoxicity and non-genotoxic carcinogenicity in vivo, by comparing microRNA- and mRNA-based profiles, using a frequently applied in vitro liver model and exposing this to a range of well-chosen prototypical carcinogens. Primary mouse hepatocytes (PMH) were treated for 24 and 48h with 21 chemical compounds [genotoxins (GTX) vs. non-genotoxins (NGTX) and non-genotoxic carcinogens (NGTX-C) versus non-carcinogens (NC)]. MicroRNA and mRNA expression changes were analysed by means of Exiqon and Affymetrix microarray-platforms, respectively. Classification was performed by using Prediction Analysis for Microarrays (PAM). Compounds were randomly assigned to training and validation sets (repeated 10 times). Before prediction analysis, pre-selection of microRNAs and mRNAs was performed by using a leave-one-out t-test. No microRNAs could be identified that accurately predicted genotoxicity or non-genotoxic carcinogenicity in vivo. However, mRNAs could be detected which appeared reliable in predicting genotoxicity in vivo after 24h (7 genes) and 48h (2 genes) of exposure (accuracy: 90% and 93%, sensitivity: 65% and 75%, specificity: 100% and 100%). Tributylinoxide and para-Cresidine were misclassified. Also, mRNAs were identified capable of classifying NGTX-C after 24h (5 genes) as well as after 48h (3 genes) of treatment (accuracy: 78% and 88%, sensitivity: 83% and 83%, specificity: 75% and 93%). Wy-14,643, phenobarbital and ampicillin trihydrate were misclassified. We conclude that genotoxicity and non-genotoxic carcinogenicity probably cannot be accurately predicted based on microRNA profiles. Overall, transcript-based prediction analyses appeared to clearly outperform microRNA-based analyses.
Exploiting microRNA and mRNA profiles generated in vitro from carcinogen-exposed primary mouse hepatocytes for predicting in vivo genotoxicity and carcinogenicity.
Specimen part, Compound
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