Fitm2 is required for ER homeostasis and normal function of murine liver
Ontology highlight
ABSTRACT:
ORGANISM(S): Mouse Mus Musculus
TISSUE(S): Liver
SUBMITTER: 
Laura Bond
PROVIDER: ST002303 | MetabolomicsWorkbench | Sat Sep 17 00:00:00 BST 2022
REPOSITORIES: MetabolomicsWorkbench
Similar Datasets
Project description:The ER-resident prote in fat-inducing transcript 2 (FIT2) catalyzes acyl-CoA cleavage in vitro, and in cells is required for endoplasmic reticulum (ER)homeostasis and normal lipid storage. The gene encoding FIT2 is essential for viability of mice and worms. Whether FIT2 acts as anacyl-CoA diphosphatase in vivo and how this activity affects liver, where the protein was discovered,is unknown. Here, we report that hepatocyte-specific Fitm2 knockout (FIT2-LKO) mice exhibited elevated acyl-CoA levels, ER stress, and signs of liver injury. FIT2-LKO mice had increased triglyceride (TG) content in liver when fed a chow diet, compared with control littermates due in part to impaired secretion of TG-rich lipoproteins and reduced capacity for fatty acid oxidation. Challenging FIT2-LKO mice with a high-fat diet to increase FIT2 acyl-CoA substrates worsened hepatic ER stress and liver injury, yet unexpectedly reversed the steatosis phenotype, similar to what is observed in FIT2-deficient cells loaded with fatty acids. Our findings show that FIT2 acts as anacyl-CoA diphosphatase in vivo and is crucial for normal hepatocyte function and ER homeostasis in murine liver
2023-05-10 | PXD033884 | Pride
Project description:Nudix hydrolase 7 (NUDT7) is a peroxisomal (acyl-)CoA-degrading enzyme that is highly expressed in the liver. We previously showed that liver-specific NUDT7 overexpression affects peroxisomal lipid metabolism, but does not prevent the increase in total liver CoA levels that occurs with fasting. Herein, we show that deletion of Nudt7 alters the composition of the hepatic acyl-CoA pool in mice fed a low fat diet, but only in males fed a western diet does the lack of NUDT7 increase total liver CoA levels. This effect is driven by the accumulation of medium-chain dicarboxylic acyl-CoAs, which are products of the oxidation of dicarboxylic fatty acids in the peroxisomes. We also show that, under conditions of increased cholesterol intake and elevated bile acid synthesis, Nudt7 deletion increases the production of tauro-muricholic acids, decreasing the hydrophobicity index of the intestinal bile acid pool and increasing fecal cholesterol excretion. Collectively, our findings reveal a key role for NUDT7 in the regulation of the final products of bile acid synthesis and dicarboxylic fatty acid oxidation
2022-11-25 | GSE207914 | GEO
Project description:vanEunen2013 - Network dynamics of fatty acid β-oxidation (steady-state model)
Lipid metabolism plays an important role in the development of metabolic syndrome, a major risk factor for cardiovascular disease and diabetes. This model gives insights into the response of lipid oxidation to dietart and medical interventions. The model predicts the rate of lipid oxidation and the time course of most acyl carnitines. There are two models described in the paper, (i) steady-state model [ BIOMD0000000505
], (ii) time-course model [ BIOMD0000000506
]. This model corresponds to the steady-state model.
This model is described in the article:
Biochemical competition makes fatty-acid β-oxidation vulnerable to substrate overload.
van Eunen K, Simons SM, Gerding A, Bleeker A, den Besten G, Touw CM, Houten SM, Groen BK, Krab K, Reijngoud DJ, Bakker BM.
PLoS Comput Biol. 2013;9(8):e1003186.
Abstract:
Fatty-acid metabolism plays a key role in acquired and inborn metabolic diseases. To obtain insight into the network dynamics of fatty-acid β-oxidation, we constructed a detailed computational model of the pathway and subjected it to a fat overload condition. The model contains reversible and saturable enzyme-kinetic equations and experimentally determined parameters for rat-liver enzymes. It was validated by adding palmitoyl CoA or palmitoyl carnitine to isolated rat-liver mitochondria: without refitting of measured parameters, the model correctly predicted the β-oxidation flux as well as the time profiles of most acyl-carnitine concentrations. Subsequently, we simulated the condition of obesity by increasing the palmitoyl-CoA concentration. At a high concentration of palmitoyl CoA the β-oxidation became overloaded: the flux dropped and metabolites accumulated. This behavior originated from the competition between acyl CoAs of different chain lengths for a set of acyl-CoA dehydrogenases with overlapping substrate specificity. This effectively induced competitive feedforward inhibition and thereby led to accumulation of CoA-ester intermediates and depletion of free CoA (CoASH). The mitochondrial [NAD⁺]/[NADH] ratio modulated the sensitivity to substrate overload, revealing a tight interplay between regulation of β-oxidation and mitochondrial respiration.
This model is hosted on BioModels Database
and identified
by: BIOMD0000000505
.
To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource
for published quantitative kinetic models
.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to the public
domain worldwide. Please refer to CC0 Public Domain
Dedication
for more information.
2014-01-15 | BIOMD0000000505 | BioModels
Project description:vanEunen2013 - Network dynamics of fatty acid β-oxidation (time-course model)
Lipid metabolism plays an important role in the development of metabolic syndrome, a major risk factor for cardiovascular disease and diabetes. This model gives insights into the response of lipid oxidation to dietart and medical interventions. The model predicts the rate of lipid oxidation and the time course of most acyl carnitines. There are two models described in the paper, (i) steady-state model [ BIOMD0000000505
], (ii) time-course model [ BIOMD0000000506
]. This model corresponds to the time-course model.
This model is described in the article:
Biochemical competition makes fatty-acid β-oxidation vulnerable to substrate overload.
van Eunen K, Simons SM, Gerding A, Bleeker A, den Besten G, Touw CM, Houten SM, Groen BK, Krab K, Reijngoud DJ, Bakker BM.
PLoS Comput Biol. 2013;9(8):e1003186.
Abstract:
Fatty-acid metabolism plays a key role in acquired and inborn metabolic diseases. To obtain insight into the network dynamics of fatty-acid β-oxidation, we constructed a detailed computational model of the pathway and subjected it to a fat overload condition. The model contains reversible and saturable enzyme-kinetic equations and experimentally determined parameters for rat-liver enzymes. It was validated by adding palmitoyl CoA or palmitoyl carnitine to isolated rat-liver mitochondria: without refitting of measured parameters, the model correctly predicted the β-oxidation flux as well as the time profiles of most acyl-carnitine concentrations. Subsequently, we simulated the condition of obesity by increasing the palmitoyl-CoA concentration. At a high concentration of palmitoyl CoA the β-oxidation became overloaded: the flux dropped and metabolites accumulated. This behavior originated from the competition between acyl CoAs of different chain lengths for a set of acyl-CoA dehydrogenases with overlapping substrate specificity. This effectively induced competitive feedforward inhibition and thereby led to accumulation of CoA-ester intermediates and depletion of free CoA (CoASH). The mitochondrial [NAD⁺]/[NADH] ratio modulated the sensitivity to substrate overload, revealing a tight interplay between regulation of β-oxidation and mitochondrial respiration.
This model is hosted on BioModels Database
and identified
by: BIOMD0000000506
.
To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource
for published quantitative kinetic models
.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to the public
domain worldwide. Please refer to CC0 Public Domain
Dedication
for more information.
2014-01-15 | BIOMD0000000506 | BioModels
Project description:In all eukaryotic cell types, the unfolded protein response (UPR) upregulates factors that promote protein folding and misfolded protein clearance to help alleviate endoplasmic reticulum (ER) stress. Yet ER stress in the liver is uniquely accompanied by the suppression of metabolic genes, the coordination and purpose of which is largely unknown. Here, we combined in silico machine learning, in vivo liver-specific deletion of the master regulator of hepatocyte differentiation HNF4α, and in vitro manipulation of hepatocyte differentiation state to determine how the UPR regulates hepatocyte identity, and toward what end. Machine learning identified a cluster of correlated genes that were profoundly suppressed by persistent ER stress in the liver. These genes, which encode diverse functions including metabolism, coagulation, drug detoxification, and bile synthesis, are likely targets of the master regulator of hepatocyte differentiation HNF4α. The response of these genes to ER stress was phenocopied by liver-specific deletion of HNF4α. Strikingly, while deletion of HNF4α exacerbated liver injury in response to an ER stress challenge, it also diminished UPR activation and partially preserved ER ultrastructure, suggesting attenuated ER stress. Conversely, pharmacological maintenance of hepatocyte identity in vitro enhanced sensitivity to stress. Together, our findings suggest that the UPR regulates hepatocyte identity through HNF4α to protect ER homeostasis even at the expense of liver function.
2023-07-04 | GSE235849 | GEO
Project description:Fasiglifam (TAK-875), a G protein-coupled receptor 40 (GPR40) agonist, was a drug candidate for type 2 diabetes. However, its development was terminated in phase 3 trials due to liver safety concerns. Although TAK-875 was reported to inhibit hepatobiliary transporters and disturb bile acid disposition, pathogenic mechanisms of TAK-875-induced liver injury are not fully understood. In this study, we sought to identify the mechanisms with a hepatic genome-wide transcriptomic analysis in a murine model. We demonstrated that, among the three GPR40 agonists, TAK-875, AMG-837 and TUG-770, only TAK-875 induced acute liver injury in mice. Transcriptome profiles of TAK-875-exposed liver was compared with those of non-hepatotoxic analogues AMG-837 and TUG-770 as negative controls and those of classical hepatotoxicants concanavalin A and carbon tetrachloride as positive controls. The comparative hepatic transcriptome analyses revealed the enrichment of genes involved in inflammation, endoplasmic reticulum (ER) stress, apoptosis, and hepatic lipid accumulation, suggesting that these events play pathophysiologic roles in the development of TAK-875-induced liver injury. These results were validated by quantitative PCR with significant changes in chemokines, danger signals, ER stress mediators, proapoptotic factors, and hepatic steatosis markers only in TAK-875-exposed liver. Pretreatment of TAK-875-administered mice with an ER stress inhibitor 4-phenylbutyric acid (4-PBA) alleviated the liver injury. Consistent with the in vivo study, pretreatment of HepG2 cells with 4-PBA significantly improved the decrease of cell viability induced by TAK-875. In conclusion, by a comprehensive transcriptomic analysis of GPR40 agonists, we found multiple possible processes that contribute to TAK-875-induced acute liver injury in mice.
2018-10-10 | GSE112140 | GEO
Project description:Floodings already have a nearly 60% share in the worldwide damage to crops provoked by natural disasters. Climate change will cause plants to be even more frequently exposed to oxygen limiting conditions (hypoxia) in the near future due to heavy precipitation and concomitant waterlogging or flooding events in large areas of the world. Although the homeostatic regulation of adaptive responses to low oxygen stress in plants is well described, it remained unknown by which initial trigger the molecular response to low-oxygen stress is activated. Here, we show that a hypoxia-induced decline of the ATP level of the cell reduces LONG-CHAIN ACYL-COA SYNTHETASE (LACS) activity, which leads to a shift in the composition of the acyl-CoA pool. High oleoyl-CoA levels release the transcription factor RELATED TO APETALA 2.12 (RAP2.12) from its interaction partner ACYL-COA BINDING PROTEIN (ACBP) at the plasma membrane to induce low oxygen-specific gene expression. We show that different acyl-CoAs provoke unique molecular responses revealing a novel role as cellular signalling component also in plants. In terms of hypoxia signalling, dynamic acyl-CoA levels integrate the cellular energy status into the oxygen signalling cascade with ACBP and RAP2.12 being the central hub. The conserved nature of the ACBP:RAP2.12 module in crops and the novel mechanistic understanding of how low-oxygen stress responses are initiated by oleoyl-CoA in plants provide useful leads for enhancing future food security.
2018-04-30 | GSE97186 | GEO
Project description:RNAseq analysis was conducted to complement the targeted and untargeted metabolomics analysis of livers overexpressing the CoA-degrading enzyme Nudt7 or GFP (control). Lipid metabolism requires coenzyme A (CoA), which is found in multiple subcellular compartments including the peroxisomes. In the liver, CoA levels are dynamically adjusted between the fed and fasted states. The elevation in CoA levels that occurs during fasting is driven by increased synthesis but also correlates with decreased expression of Nudt7, the major CoA-degrading enzyme in the liver. Nudt7 resides in the peroxisomes and we overexpressed this enzyme in mouse livers to determine its effect on the size and composition of the hepatic CoA pool in the fed and fasted states. Nudt7 overexpression did not change total CoA levels but decreased the concentration of short-chain acyl-CoAs and choloyl-CoA in fasted livers, when endogenous Nudt7 activity was lowest. The effect on these acyl-CoAs correlated with a significant decrease in the hepatic bile acid content and in the rate of peroxisomal fatty acid oxidation, as estimated by targeted and untargeted metabolomics, combined with the measurement of fatty acid oxidation in intact hepatocytes. Identification of the CoA species and metabolic pathways affected the overexpression on Nudt7 in vivo supports the conclusion that the nutritionally-driven modulation of Nudt7 activity could contribute to the regulation of the peroxisomal CoA pool and peroxisomal lipid metabolism.
2019-03-08 | GSE125237 | GEO
Project description:The effects of high-fat (HF) feeding on the gene expression in the small intestine were examined using obesity-resistant A/J mice and obesity-sensitive C57BL/6J (B6) mice. Both strains of mice were maintained on low-fat (LF, 5% fat) or HF (30% fat) diets for two weeks. Oligonucleotide microarray and semi-quantitative RT-PCR analysis revealed that lipid metabolism-related genes including mitochondrial acyl-CoA thioesterase 1, pyruvate dehydrogenase kinase 4, and NADP+-dependent cytosolic malic enzyme were up-regulated by more than 2-fold in both strains of mice. The up-regulated gene expression levels were significantly higher in A/J mice than in B6 mice, suggesting the active lipid metabolism in the small intestine of A/J mice. Experiment Overall Design: Mice were maintained on the LF or HF diet for two weeks. For each group (n=6), pooled total RNA from two mice of average body weight was used for the analysis.
2008-11-06 | E-GEOD-3433 | biostudies-arrayexpress
Project description:Accumulation of unfolded or misfolded proteins in the endoplasmic reticulum (ER) lumen triggers unfolded protein response (UPR) for stress adaptation, the failure of which induces cell apoptosis and tissue/organ damage. The molecular switches underlying how the UPR selects for stress adaptation over apoptosis remain unknown. Here we discovered that accumulation of unfolded/misfolded proteins selectively induces N6-adenosine-methyltransferase-14 (METTL14) expression. METTL14 promotes CHOP mRNA decay through its 3’UTR N6-adenosine methylation (m6A) to inhibit its downstream pro-apoptotic target genes expression. UPR induces METTL14 expression through competing the HRD1-ERAD machinery to block METTL14 ubiquitination and degradation. Therefore, mice with liver-specific METTL14 deletion are highly susceptible to both acute pharmacological and alpha-1 antitrypsin (AAT) deficiency-induced ER proteotoxic stress and liver injury. Further hepatic CHOP deletion protects METTL14 knockout mice from ER stress-induced liver damage. Our study reveals a crosstalk between ER stress and mRNA m6A pathways, the ERm6A pathway, for ER stress adaptation to proteotoxicity.
2021-09-30 | GSE185109 | GEO