Transcriptional responses of human insulinoma cells to acute cytokine exposure
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE134122 | GEO | 2019/10/07
REPOSITORIES: GEO
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Project description:The Akita mutation (C96Y) in the insulin gene results in early onset diabetes in both humans and mice. Expression of the mutant proinsulin (C96Y) causes endoplasmic reticulum (ER) stress in pancreatic -cells and consequently the cell activates the unfolded protein response (UPR). Since the proinsulin is terminally misfolded however, the ER stress is irremediable and chronic activation of the UPR eventually activates apoptosis in the cell population. We used microarray gene expression arrays to analyze the IRE1-dependent activation of genes in response to misfolded proinsulin expression in an inducible mutant proinsulin (C96Y) insulinoma cell line by inhibiting the IRE1 endoribonucleas activity with a specific inhibitor, 4u8c.
2014-07-16 | GSE58866 | GEO
Project description:The Akita mutation (C96Y) in the insulin gene results in early onset diabetes in both humans and mice. Expression of the mutant proinsulin (C96Y) causes endoplasmic reticulum (ER) stress in pancreatic ?-cells and consequently the cell activates the unfolded protein response (UPR). Since the proinsulin is terminally misfolded however, the ER stress is irremediable and chronic activation of the UPR eventually activates apoptosis in the cell population. We used microarray gene expression arrays to analyze the IRE1-dependent activation of genes in response to misfolded proinsulin expression in an inducible mutant proinsulin (C96Y) insulinoma cell line by inhibiting the IRE1 endoribonucleas activity with a specific inhibitor, 4u8c. Insulinoma cells with doxycycline inducible C96Y-proinsulin expression were either untreated, treated with doxycycline alone or treated with dox and 4u8c. This was done with two biological replicates.
2014-07-16 | E-GEOD-58866 | biostudies-arrayexpress
Project description:The unfolded protein response (UPR), a signaling pathway triggered by endoplasmic reticulum (ER) stress, is induced by a range of environmental factors. Here we describe the identification and characterization of a synthetic small molecule, erstressin, which activates the UPR. Erstressin induced rapid phosphorylation of PERK and eIF2a and the alternative splicing of XBP-1, hallmark initiating events of the UPR. Further, erstressin activated the transcription of multiple genes involved in the UPR. Coincident with these effects, erstressin also downregulated the transcription of the inflammation-associated enzyme inducible nitric oxide synthase (iNOS) in cytokine-activated cells. A close analog of erstressin that failed to induce the UPR did not attenuate expression of iNOS, suggesting that both biological effects of erstressin were mediated by a common mechanism. Further, the structurally-distinct ER stressor thapsigargin also inhibited iNOS expression. Together these chemical genetic studies reveal an unanticipated anti-inflammatory role for the UPR. Experiment Overall Design: We utilized microarrays to understand the global effect of a novel compund, erstressin, on cytokine stimulated cells over time.
2008-06-15 | E-GEOD-7806 | biostudies-arrayexpress
Project description:The accumulation of unfolded proteins in the lumen of the endoplasmic reticulum (ER) causes stress and induces the unfolded protein response (UPR) which is characterised in part by the transcriptional induction of genes involved in assisting protein folding. Translational responses to ER stress have been less well described and here we report on a genome-wide analysis of translational regulation in the response to the ER stress-inducing agent dithiothreitol (DTT) in Saccharomyces cerevisiae. Although the observed polysome profiles were similar under control and ER stress conditions microarray analysis identified transcipt-specific translational regulation. Genes with functions in ribosomal biogenesis and assembly were translationally repressed under ER stress. In contrast mRNAs for known UPR genes, including the UPR transcription factor HAC1, the ER-oxidoreductase ERO1 and the ER-associated protein degradation (ERAD) gene DER1 were enriched in polysomal fractions under ER stress conditions. In addition, we show that splicing of HAC1 mRNA is required for efficient ribosomal loading and that Gcn2p is required for normal HAC1 splicing, so shedding light on the role of this protein kinase in the UPR pathway. Experiment Overall Design: Polyribosomes were extracted from S. cerevisiae cells treated with 2 mM DTT or water (control), and fractionated according to ribosome loading. Following RNA purification from these fractions, for each sub-polysomal and polysomal RNA sample, fractions from three independent extracts per treatment (DTT/control) were pooled.
2008-06-11 | E-GEOD-10091 | biostudies-arrayexpress
Project description:Erguler2013 - Unfolded protein stress response
The model investigates the mechanism by which UPR (unfolded protein response) outcome switches between survival and death.
This model is described in the article:
A mathematical model of the unfolded protein stress response reveals the decision mechanism for recovery, adaptation and apoptosis.
Erguler K, Pieri M, Deltas C.
BMC Syst Biol. 2013 Feb 21;7(1):16.
Abstract:
BACKGROUND: The unfolded protein response (UPR) is a major signalling cascade acting in the quality control ofprotein folding in the endoplasmic reticulum (ER). The cascade is known to play an accessory rolein a range of genetic and environmental disorders including neurodegenerative and cardiovasculardiseases, diabetes and kidney diseases. The three major receptors of the ER stress involved withthe UPR, i.e. IRE1a, PERK and ATF6, signal through a complex web of pathways to convey anappropriate response. The emerging behaviour ranges from adaptive to maladaptive depending on theseverity of unfolded protein accumulation in the ER; however, the decision mechanism for the switchand its timing have so far been poorly understood.
RESULTS:
Here, we propose a mechanism by which the UPR outcome switches between survival and death.We compose a mathematical model integrating the three signalling branches, and perform a comprehensivebifurcation analysis to investigate possible responses to stimuli. The analysis reveals threedistinct states of behaviour, low, high and intermediate activity, associated with stress adaptation, tolerance,and the initiation of apoptosis. The decision to adapt or destruct can, therefore, be understoodas a dynamic process where the balance between the stress and the folding capacity of the ER playsa pivotal role in managing the delivery of the most appropriate response. The model demonstratesfor the first time that the UPR is capable of generating oscillations in translation attenuation and theapoptotic signals, and this is supplemented with a Bayesian sensitivity analysis identifying a set ofparameters controlling this behaviour.
CONCLUSIONS:
This work contributes largely to the understanding of one of the most ubiquitous signalling pathwaysinvolved in protein folding quality control in the metazoan ER. The insights gained have direct consequenceson the management of many UPR-related diseases, revealing, in addition, an extended listof candidate disease modifiers. Demonstration of stress adaptation sheds light to how preconditioningmight be beneficial in manifesting the UPR outcome to prevent untimely apoptosis, and paves the wayto novel approaches for the treatment of many UPR-related conditions.
In the paper, PERKA refers to the amount of phosphorylated PERK monomer. However, it refers to the active complex in the model. The complex with the model parameterization is formed of 4 monomers (n=4). So, the value of PERKA should be multiplied by 4, in order to generate the figures in the paper (eg. Figure 12).
An additional parameter (tmr=10)) is used in the model. This parameter is not mentioned in the paper. The model values of kf(=10) and kr(=1) are not consistent with that of the paper (kf=100, kr=10, in the paper). However, this is corrected by the introduction of "tmr" in the model, which is multiplied with kf and kr to get the resulting values.
The term "tmr" was missing in the kinetic laws of the reactions reu7 and reu8, in the original model. This has been corrected as per the author's request.
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2024-09-02 | BIOMD0000000446 | BioModels
Project description:To dissect the requirements of membrane protein degradation from the ER, we expressed the mouse major histocompatibility complex class I heavy chain H-2K(b) in yeast. Like other proteins degraded from the ER, unassembled H-2K(b) heavy chains are not transported to the Golgi but are degraded in a proteasome-dependent manner. The overexpression of H-2K(b) heavy chains induces the unfolded protein response (UPR). In yeast mutants unable to mount the UPR, H-2K(b) heavy chains are greatly stabilized. This defect in degradation is suppressed by the expression of the active form of Hac1p, the transcription factor that upregulates UPR-induced genes. These results indicate that induction of the UPR is required for the degradation of protein substrates from the ER.
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Project description:The unfolded protein response (UPR), a signaling pathway triggered by endoplasmic reticulum (ER) stress, is induced by a range of environmental factors. Here we describe the identification and characterization of a synthetic small molecule, erstressin, which activates the UPR. Erstressin induced rapid phosphorylation of PERK and eIF2a and the alternative splicing of XBP-1, hallmark initiating events of the UPR. Further, erstressin activated the transcription of multiple genes involved in the UPR. Coincident with these effects, erstressin also downregulated the transcription of the inflammation-associated enzyme inducible nitric oxide synthase (iNOS) in cytokine-activated cells. A close analog of erstressin that failed to induce the UPR did not attenuate expression of iNOS, suggesting that both biological effects of erstressin were mediated by a common mechanism. Further, the structurally-distinct ER stressor thapsigargin also inhibited iNOS expression. Together these chemical genetic studies reveal an unanticipated anti-inflammatory role for the UPR. Keywords: Time course
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