DTORC gene profiling
Ontology highlight
ABSTRACT:
ORGANISM(S): Drosophila melanogaster
PROVIDER: GSE10546 | GEO | 2008/07/04
SECONDARY ACCESSION(S): PRJNA107909
REPOSITORIES: GEO
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Project description:In fasted mammals, glucose homeostasis is maintained through activation of the cAMP responsive CREB coactivator TORC2, which stimulates the gluconeogenic program in concert with the forkhead transcription factor FOXO1. Here we show that starvation also triggers TORC activation in Drosophila, where it maintains energy balance by promoting the expression of CREB target genes in the brain. TORC mutant flies have reduced glycogen and lipid stores, and they are sensitive to starvation as well as oxidative stress. Neuronal TORC expression rescued starvation and oxidative stress sensitivity as well as CREB target gene expression in TORC mutants. During refeeding, increases in insulin signaling inhibited TORC activity in wild type flies by stimulating the Salt Inducible Kinase 2 (SIK2)-mediated phosphorylation and subsequent degradation of TORC. Depletion of neuronal SIK2 increased TORC activity and enhanced resistance to starvation and oxidative stress in adult flies. As disruption of insulin signaling, either by ablation of insulin-producing cells (IPCs) or by mutation of the insulin receptor adaptor gene chico, also increased TORC activity, our results illustrate the importance of an insulin-regulated pathway in brain that promotes energy balance in Drosophila. Experiment Overall Design: Male fly heads were collected after 24h fasting, and RNA was extracted using RNAeasy kit.
2008-10-20 | E-GEOD-10546 | biostudies-arrayexpress
Project description:dFOXO targets in adult Drosophila melanogaster females, and the effect of insulin signalling and stress on binding. The experimets determined the binding locations of dFOXO in the whole adult female fly using ChIP-chip. The protocol was validated using mock conditions: pre-immune serum or IP on chromatin from foxo null flies. The response of this binding to stress induced by treatment of flies with paraquat or by their exposure to starvation, as well as the response to an insulin-signalling-reducing genetic manipulation (over-expression of dominant negative form of the insulin receptor), was determined.
2011-06-18 | E-TABM-751 | biostudies-arrayexpress
Project description:Obesity stimulates the infiltration of adipose tissue by innate immune cells, which in turn promote insulin resistance via the NFkB mediated induction of pro-inflammatory cytokines, which interfere with triglyceride metabolism. The cAMP responsive factor CREB has also been implicated in adipose tissue inflammation and insulin resistance, although the underlying mechanism is unclear. Here, we show that high fat diet (HFD) feeding triggers activation of the CREB cofactors CRTC2 and CRTC3, which bind to CREB and mediate induction of CXCL1 and other cytokine genes in cooperation with NFkB. HFD feeding reduced adipocyte C/EBPa expression in adipose, leading to decreases in the expression of Salt Inducible Kinase 2 (SIK2), which otherwise phosphorylates and sequesters CRTCs in the cytoplasm. Depletion of SIK2 in adipose led to dephosphorylation of CRTC2 and CRTC3 (CRTC2/3) and to the induction of CXCL1 and other cytokine genes in adipocytes. Indeed, CRTC2/3 were found to stimulate the expression of a subset of cellular genes cooperatively with NF-kB in adipocytes. Knockout of both CRTC2 and CRTC3 in adipose decreased the expression of CXCL1/2 and thereby reduced neutrophil and macrophage infiltration. As depletion of CXCL1/2, with neutralizing antiserum or by KO of the CXCL1 gene restored glucose tolerance and insulin sensitivity in the setting of diet induced obesity, our results demonstrate that NF-kB and CREB/CRTC pathways modulate adipose tissue function in part via cooperative effects on target gene expression.
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Project description:Lipins are eukaryotic proteins with functions in lipid synthesis and the homeostatic control of energy balance. They execute these functions by acting as phosphatidate phosphatase enzymes in the cytoplasm and by changing gene expression after translocation into the cell nucleus, in particular under fasting conditions. Here, we asked how gene expression changes, under both fed and fasting conditions, when nuclear translocation of Lipin is impaired. To address this question, we created a Drosophila mutant expressing Lipin lacking a nuclear localization signal (LipinDNLS). Notably, adult LipinDNLS flies were not only viable but also exhibited improved life expectancy. In contrast, they were highly susceptible to starvation. To examine how these phenotypes correlate with changes in gene expression, we carried out an RNA-seq analysis with mRNA from female and male LipinDNLS and control flies that had been kept under fed or fasting conditions. We found that genes involved in metabolism, feeding behavior, and the immune response were mis-regulated in LipinDNLS flies. The changed expression of these genes supports hypotheses explaining improved life expectancy under fed and decreased life expectancy under fasting conditions. For instance, metabolic rate measurements confirmed the prediction based on the RNA-seq data that energy production by oxidative phosphorylation is reduced in fed LipinDNLS flies.
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2010-12-21 | E-GEOD-23902 | biostudies-arrayexpress
Project description:Smith2013 - Regulation of Insulin Signalling by Oxidative Stress
The model describes insulin signalling (in rodent adipocytes), which includes in addition to the core pathway, the transcriptional feedback through the Forkhead box type O (FOXO) transcription factor and interaction with oxidative stress.
This model is described in the article:
Computational modelling of the regulation of Insulin signalling by oxidative stress.
Smith GR, Shanley DP.
BMC Syst Biol. 2013 May 24;7:41.
Abstract:
BACKGROUND:
Existing models of insulin signalling focus on short term dynamics, rather than the longer term dynamics necessary to understand many physiologically relevant behaviours. We have developed a model of insulin signalling in rodent adipocytes that includes both transcriptional feedback through the Forkhead box type O (FOXO) transcription factor, and interaction with oxidative stress, in addition to the core pathway. In the model Reactive Oxygen Species are both generated endogenously and can be applied externally. They regulate signalling though inhibition of phosphatases and induction of the activity of Stress Activated Protein Kinases, which themselves modulate feedbacks to insulin signalling and FOXO.
RESULTS:
Insulin and oxidative stress combined produce a lower degree of activation of insulin signalling than insulin alone. Fasting (nutrient withdrawal) and weak oxidative stress upregulate antioxidant defences while stronger oxidative stress leads to a short term activation of insulin signalling but if prolonged can have other effects including degradation of the insulin receptor substrate (IRS1) and FOXO. At high insulin the protective effect of moderate oxidative stress may disappear.
CONCLUSION:
Our model is consistent with a wide range of experimental data, some of which is difficult to explain. Oxidative stress can have effects that are both up- and down-regulatory on insulin signalling. Our model therefore shows the complexity of the interaction between the two pathways and highlights the need for such integrated computational models to give insight into the dysregulation of insulin signalling along with more data at the individual level.A complete SBML model file can be downloaded from BIOMODELS (https://www.ebi.ac.uk/biomodels-main) with unique identifier MODEL1212210000.Other files and scripts are available as additional files with this journal article and can be downloaded from https://github.com/graham1034/Smith2012_insulin_signalling.
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2024-09-02 | BIOMD0000000474 | BioModels
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