Hepatocytes cyclooxygenase-2 deficiency improves liver injury via inhibition of endoplasmic reticulum stress and epithelial-mesenchymal transition
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE183888 | GEO | 2024/04/28
REPOSITORIES: GEO
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Project description:Alterations in endoplasmic reticulum (ER) homeostasis have been implicated in the pathophysiology of obesity and type-2 diabetes (T2D). Acute ER stress induction in the hypothalamus produces glucose metabolism perturbations. However, the neurobiological basis linking hypothalamic ER stress with abnormal glucose metabolism remains unknown. Here we report that genetic and induced models of hypothalamic ER stress are associated with alterations in systemic glucose homeostasis due to increased gluconeogenesis (GNG) independent of body weight changes. Defective alpha melanocyte-stimulating hormone (a-MSH) production underlies this metabolic phenotype, as pharmacological strategies aimed at rescuing hypothalamic a-MSH content reversed this phenotype at metabolic and molecular level. Collectively, our results posit defective a-MSH processing as a fundamental mediator of enhanced GNG in the context of hypothalamic ER stress, and establish a-MSH deficiency in proopiomelanocortin (POMC) neurons as a potential contributor to the pathophysiology of T2D. Total RNA was extracted from whole-liver of 6-week old control (3 biological replicates) and POMCMfn2KO mice (5 biological replicates)
2015-06-18 | E-GEOD-62263 | biostudies-arrayexpress
Project description:We are currently studying how these information-carrying oligosaccharides are involved in cellular stress responses, particularly in human genetic diseases called Congenital Disorders Of Glycosylation in which oligosaccharide assembly is defective. We are interested in endoplasmic stress responses/unfolded protein responses. ER glycans and ER lectins are intimately involved in the folding of ER proteins. Therefore, ER lectins and ER glycosyltransferases may be controlled by these stress responses, to produce and/or recognize key glycans in the stress response. Our model system is the human dermal fibroblast. We have successfully calibrated the ER stress responses in these cells by determining the magnitudes of various stress effects (such as chaperone transcription) with different forms of ER stress. We are also completing a study in which activation the signaling molecules Ire1 and ATF6 are also calibrated. We prepared multiple identical aliquots of RNA from cells stressed under several of these calibrated conditions. Endoplasmic reticulum (ER) stress and the unfolded protein response (UPR): Study of the role of ER stress in the expression of genes for ER transferases and lectins that participate in ER folding and quality control using human skin fibroblasts. The UPR response in these cells has been calibrated using various readouts in response to different stresses: 1) 40 nM L-azetidine-2-carboxylate (AZC) 1 hour, 2) 0.2 mg/ml castanospermine, 24 hours, 3) 2 mM Dithiothreitol (DTT), 20 minutes, 4) 100nm Thapsigargin (TG), 30 minutes, 5) 5 ug/ml tunicamycin, 5 hours, 6) untreated control cells
2011-02-17 | E-GEOD-27349 | biostudies-arrayexpress
Project description:BACKGROUND: As evidenced by epidemiological and etiological studies, the development of varicose veins is driven by risk-factors which support the development of venous hypertension and thus chronically augment circumferential stress of the venous wall (e.g. dysfunctional venous valves, pregnancy or obesity). We have previously verified the relevance of this biomechanical stimulus for the activation of venous endothelial as well as smooth muscle cells and the subsequent detrimental structural remodeling of the vein wall in experimental mouse models. METHODS: Here, transcriptome analyses revealed an increase in the expression of cyclooxygenase 2 (COX-2) in human venous endothelial cells upon exposure to biomechanical stress. Subsequently, we investigated the impact of diclofenac – a cyclooxygenase inhibitor – on responses of isolated mouse veins to augmented wall stress in vitro and on varicose-like venous remodeling in vivo. RESULTS: Diclofenac treatment decreased COX-2 protein abundance in mouse veins but had no significant impact on the expression of corresponding transcripts. Short-term exposure to elevated pressure levels stimulated the activity of matrix-metalloproteinase-2 (MMP-2) and mitogen activated protein kinases ERK1/2. Diclofenac decreased the level of activated MMP-2 and ERK1/2 in pressure-exposed mouse veins. Varikose-like remodeling of veins in the mouse auricle was significantly inhibited by transdermal application of diclofenac-containing phospholipid-micelles. This effect was associated with decreased COX-2 and MMP-2 abundance as well as cell proliferation. CONCLUSION: The cyclooxygenase inhibitor diclofenac interferes with short term activation of MAP-kinases and matrix-metalloproteinases in cells of the wall stress-exposed venous wall while attenuating venous remodeling in vivo. Thus, nonsteroidal anti-inflammatory drugs may be suitable to interfere with processes promoting the progression of varicose vein development and biomechanical activation of venous cells.
2021-01-12 | GSE121557 | GEO
Project description:Chronic endoplasmic reticulum (ER) stress results in toxicity that contributes to multiple human disorders. We report a stress resolution pathway initiated by the nuclear receptor LRH-1 that is independent of known unfolded protein response (UPR) pathways. Like mice lacking primary UPR components, hepatic Lrh-1-null mice cannot resolve ER stress, despite a functional UPR. In response to ER stress, LRH-1 induces expression of the kinase Plk3, which phosphorylates and activates the transcription factor ATF2. Plk3-null mice also cannot resolve ER stress, and restoring Plk3 expression in Lrh-1-null cells rescues ER stress resolution. Reduced or heightened ATF2 activity also sensitizes or desensitizes cells to ER stress, respectively. LRH-1 agonist treatment increases ER stress resistance and decreases cell death. We conclude that LRH-1 initiates a novel pathway of ER stress resolution that is independent of the UPR, yet equivalently required. Targeting LRH-1 may be beneficial in human disorders associated with chronic ER stress. 24 total samples. One sample represents one mouse. Three samples were analyzed from the following groups: Lrh-1 f/f (control littermates) treated with vehicle, Lrh-1 f/f treated with tunicamycin (TM; 1mg/kg BW for 24h), Lrh-1 f/f treated with tunicamycin and DLPC (100mg/kg BW 4x), Lrh-1 f/f treated with tunicamycin and vehicle for DLPC, Lrh-1 liver-specific KO mice (LKO) treated with vehicle, Lrh-1 LKO treated with tunicamycin, and Lrh-1 LKO treated with tunicamycin and DLPC, Lrh-1 LKO treated with tunicamycin and vehicle for DLPC
2015-05-12 | E-GEOD-68718 | biostudies-arrayexpress
Project description:Effects of calcitriol on expressions of ER stress related genes were evaluated with microarray. Calcitriol, the active form of vitamin D, is known to induce apoptosis in cancer cells and increase intracellular calcium. Increase in cytopalsmic calcicium levels may indicate a decrease in endoplasmic reticulum (ER) calcium levels since ER is the main storage unit for calcium. Decrease in ER calcium levels are known to induce ER stress which can lead to apoptosis. However the effects of calcitriol on ER stress have not been reported before. Here we hypotesized that the cellular effects of calcitriol can be explained by induction of ER stress. We have tested this hypothesis by assessing calcitriol induced transcriptomic alterations with a focus on ER stress related genes.
2015-01-01 | GSE53975 | GEO
Project description:We are currently studying how these information-carrying oligosaccharides are involved in cellular stress responses, particularly in human genetic diseases called Congenital Disorders Of Glycosylation in which oligosaccharide assembly is defective. We are interested in endoplasmic stress responses/unfolded protein responses. ER glycans and ER lectins are intimately involved in the folding of ER proteins. Therefore, ER lectins and ER glycosyltransferases may be controlled by these stress responses, to produce and/or recognize key glycans in the stress response. Our model system is the human dermal fibroblast. We have successfully calibrated the ER stress responses in these cells by determining the magnitudes of various stress effects (such as chaperone transcription) with different forms of ER stress. We are also completing a study in which activation the signaling molecules Ire1 and ATF6 are also calibrated. We prepared multiple identical aliquots of RNA from cells stressed under several of these calibrated conditions.
2011-02-17 | GSE27349 | GEO
Project description:Liver injury is a core pathological process in the majority of liver diseases, yet the genetic factors predisposing individuals to its initiation and progression remain poorly understood. Here we show that asialoglycoprotein receptor 1 (ASGR1), a lectin specifically expressed in the liver, is downregulated in patients with liver fibrosis or cirrhosis and male mice with liver injury. ASGR1 deficiency exacerbates while its overexpression mitigates acetaminophen-induced acute and CCl4-induced chronic liver injuries in male mice. Mechanistically, ASGR1 binds to an endoplasmic reticulum stress mediator GP73 and facilitates its lysosomal degradation. ASGR1 depletion increases circulating GP73 levels and promotes the interaction between GP73 and BIP to activate endoplasmic reticulum stress, leading to liver injury. Neutralization of GP73 not only attenuates ASGR1 deficiency-induced liver injuries but also improves survival in mice received a lethal dose of acetaminophen. Collectively, these findings identify ASGR1 as a potential genetic determinant of susceptibility to liver injury and propose it as a therapeutic target for the treatment of liver injury.
2023-11-26 | GSE232677 | GEO
Project description:Disruptions 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/eIF2α~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. 14 gene expression arrays, 3 WT control arrays; 3 lsPERK control arrays; 4 WT Treated arrays; 4 lsPERK treated arrays. Comparison of gene expression profiles for treated vs control in wildtype and knock-out.
2012-01-20 | E-GEOD-29929 | biostudies-arrayexpress
Project description:cdipt is an essential gene in the synthesis of phosphatidylinositol (PtdIns) in the zebrafish, Danio rerio. The zebrafish mutant cdipt^hi559Tg (ZL782) carries a retroviral insertion which inactivates cdipt. Homozygous mutants exhibit hepatocellular endoplasmic reticulum (ER) stress and non-alcoholic fatty liver disease (NAFLD) pathologies at 5 days post fertilization (dpf). This study reveals a novel link between PtdIns, ER stress, and steatosis. We compared whole animal gene expression profiles of hi559 mutant larvae with phenotypically wild type larvae from a heterozygote incross in triplicate.
2011-05-09 | E-GEOD-17711 | biostudies-arrayexpress
Project description:Metabolic disorders such as obesity and nonalcoholic fatty liver disease (NAFLD) are emerging disorders that affect the global population. One facet of the disorders is attributed to the disturbance of membrane lipid homeostasis. Perturbation of endoplasmic reticulum (ER) homeostasis through changes in membrane phospholipid composition results in activation of the unfolded protein response (UPR) and causes dramatic translational and transcriptional changes in cell. To restore cellular homeostasis, the three highly conserved UPR transducers ATF6, IRE1, and PERK mediate cellular processes upon ER stress. The roles of the UPR in proteostatic stress caused by the accumulation of misfolded protein is well understood but lipid perturbation-induced UPR remains elusive. We found that genetically attenuated PC synthesis in C. elegans causes lipid droplets accumulation if not for the intervention of the UPR program. Transcriptional profiling of lipid perturbation-induced ER stress animals shows a unique subset of genes modulated in an UPR-dependent manner that are unaffected by proteostatic stress. Among these, we identified IRE1-modulated autophagy genes that trigger liberation of free fatty acids from excess lipid droplets suggesting a stress release mechanism by which free fatty acids are rechannelling to restore lipid homeostasis. Considering the important role of lipid homeostasis and how its impairment contributes to the pathologies in metabolic diseases, our data uncovers the indispensable role of a fully functional UPR program in regulating lipid homeostais in the face of chronic ER stress.
2018-10-31 | GSE99763 | GEO