Enterocyte Superoxide Dismutase 2 Deletion Drives Hyperinsulinemia and Obesity
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ABSTRACT:
PROVIDER: PRJNA664402 | ENA |
REPOSITORIES: ENA
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Project description:Compelling evidence support an involvement of oxidative stress and intestinal inflammation as early events in the predisposition and development of obesity and its related comorbidities. Here we show that deficiency of the major mitochondrial antioxidant enzyme superoxide dismutase 2 (SOD2) in the gastrointestinal tract drives spontaneous obesity. Intestinal epithelium-specific Sod2 ablation in mice induced adiposity, inflammation and insulin resistance via phospholipase A2 (PLA2) activation and increased synthesis of omega-6 polyunsaturated fatty acid arachidonic acid. Remarkably, this obese and hyperinsulinemic phenotype was rescued when fed an essential fatty acid deficient diet, which abrogates de novo biosynthesis of arachidonic acid. Data from clinical samples revealed that the negative correlation between intestinal SOD2 mRNA levels and obesity features, such as body mass index and omega-6/omega-3 fatty acid ratio, appears to be conserved between mice and humans. Collectively, our findings suggest a role of intestinal SOD2 levels, PLA2 activity and arachidonic acid in obesity presenting new potential targets of therapeutic interest in the context of this metabolic disorder.
2021-12-31 | GSE158237 | GEO
Project description: Not available
| S-EPMC8753186 | biostudies-literature
Project description:Superoxide radical anion and other Reactive Oxygen Species are constantly produced during respiration. In mitochondria, the dismutation of the superoxide radical anion is accelerated by the mitochondrial superoxide dismutase 2 (SOD2), an enzyme that has been traditionally associated with antioxidant protection. However, increases in SOD2 expression promote oxidative stress, indicating that there may be a prooxidant role for SOD2. We show that SOD2, which normally binds manganese, can incorporate iron and generate an alternative isoform with peroxidase activity. The switch from manganese to iron allows FeSOD2 to utilize H2O2 to promote oxidative stress. We found that FeSOD2 is formed in cultured cells. FeSOD2 causes mitochondrial dysfunction and higher levels of oxidative stress in cultured cells. We show that formation of FeSOD2 converts an antioxidant defense into a prooxidant peroxidase that leads to cellular changes seen in multiple human diseases.
2017-12-05 | GSE106206 | GEO
Project description:Switch of mitochondrial superoxide dismutase into a prooxidant peroxidase in manganese-deficient cells
| PRJNA415919 | ENA
Project description:The rising incidence of pancreatic cancer is largely driven by the skyrocketing prevalence of obesity and type 2 diabetes (T2D). Hyperinsulinemia is a cardinal feature of both conditions, and is independently associated with increased cancer incidence and mortality. Our previous studies demonstrated that genetically reducing insulin production suppressed formation of pancreatic intraepithelial neoplasia (PanIN) pre-cancerous lesions in mice with mutant Kras. However, we found that hyperinsulinemia affected many cell types in the pancreatic microenvironment. Thus, it remained unclear whether hyperinsulinemia exerted its effects directly on the cells that give rise to PanINs or indirectly on the tumor microenvironment, and molecular mechanisms involved were unknown. Here, we tested whether insulin receptors (Insr) in KrasG12D-expressing pancreatic acinar cells are necessary for the effects of hyperinsulinemia on obesity-associated pancreatic cancer development. Loss of Insr in KrasG12D-expressing acinar cells did not prevent hyperinsulinemia or weight gain associated with high fat diet (HFD) consumption in mice. However, solely reducing Insr in KrasG12D-expressing acinar cells significantly reduced formation of PanIN and tumors, in a gene dose-dependent manner. Mechanistically, proteomic analyses showed that hyperinsulinemia acts through Insr to drive the excess production of digestive enzymes in acinar cells by modulating the activity of the spliceosome, ribosome, and secretory machinery. This resulted in increased inflammation, which was abrogated by acinar-specific Insr knockout. We confirmed that insulin increased the conversion of wild-type acinar cells into acinar-to-ductal metaplasia (ADM) in a trypsin-dependent manner. Collectively, these data demonstrate that hyperinsulinemia acting via acinar cells insulin receptors promotes inflammatory conditions that cooperate with Kras signaling to increase the risk of developing pancreatic cancer, mechanistically linking obesity and pancreatic cancer.
2023-08-01 | GSE229053 | GEO
Project description:Visceral adipose tissue (VAT) regulatory T cells (Tregs) control inflammation and metabolism. Diet-induced obesity causes hyperinsulinemia and diminishes VAT Treg number and function, but whether these two phenomena were mechanistically linked was unknown. We hypothesized that excessive insulin signaling in obesity negatively impact VAT Tregs. Using Treg-specific insulin receptor deletion (Foxp3-cre;Insr-fl/fl) mice, we compared the gene expression of VAT Tregs from control and knockout mice in obesity and aging, two models of hyperinsulinemia. We found that genes associated with Treg functions were altered in Tregs lacking insulin receptor.
2020-05-22 | GSE151016 | GEO
Project description:Inflammasome activation in adipose tissue has been implicated in obesity-associated insulin resistance and type 2 diabetes. However, when and how inflammasome is activated in adipose tissue remains speculative. Here we test the hypothesis that extracellular ATP, a potent stimulus of inflammasome in macrophages via purinergic receptor P2X, ligand-gated ion channel, 7 (P2X7), may play a role in inflammasome activation in adipose tissue in obesity. Our data show that inflammasome is activated in adipose tissue upon 8-week feeding of 60% HFD, coinciding with the onset of hyperglycemia and hyperinsulinemia as well as the induction of P2X7 in adipose tissue. Unexpectedly, P2X7-deficient animals on HFD exhibit no changes in metabolic phenotypes, nor in inflammatory responses or inflammasome activation when compared to the wildtype controls. Similar observations have been obtained in hematopoietic cell-specific P2X7-deficient animals generated by bone marrow transplantation. Thus, we conclude that inflammasome activation in adipose tissue in obesity coincides with the onset of hyperglycemia and hyperinsulinemia, but unexpectedly, is not mediated by the ATP-P2X7 signaling axis. The nature of the inflammasome-activating danger signal(s) in adipose tissue in obesity remains to be characterized. Wild type and P2X7 knockout mice were fed a low fat diet (chow) or high fat diet for 12 weeks. After the diet intervention period, the animals were killed and epididymal white adipose tissue was removed. Total RNA was isolated and subjected to gene expression profiling.
2012-02-24 | E-GEOD-36033 | biostudies-arrayexpress
Project description:Superoxide dismutase-3 downmodulates laminin α5 expression in endothelial cells via Nuclear Factor kappa B signaling inhibition
| PRJNA782194 | ENA
Project description:Inflammasome activation in adipose tissue has been implicated in obesity-associated insulin resistance and type 2 diabetes. However, when and how inflammasome is activated in adipose tissue remains speculative. Here we test the hypothesis that extracellular ATP, a potent stimulus of inflammasome in macrophages via purinergic receptor P2X, ligand-gated ion channel, 7 (P2X7), may play a role in inflammasome activation in adipose tissue in obesity. Our data show that inflammasome is activated in adipose tissue upon 8-week feeding of 60% HFD, coinciding with the onset of hyperglycemia and hyperinsulinemia as well as the induction of P2X7 in adipose tissue. Unexpectedly, P2X7-deficient animals on HFD exhibit no changes in metabolic phenotypes, nor in inflammatory responses or inflammasome activation when compared to the wildtype controls. Similar observations have been obtained in hematopoietic cell-specific P2X7-deficient animals generated by bone marrow transplantation. Thus, we conclude that inflammasome activation in adipose tissue in obesity coincides with the onset of hyperglycemia and hyperinsulinemia, but unexpectedly, is not mediated by the ATP-P2X7 signaling axis. The nature of the inflammasome-activating danger signal(s) in adipose tissue in obesity remains to be characterized.
2012-02-24 | GSE36033 | GEO