Removing a Double Bond from Ceramides Ameliorates Insulin Resistance and Hepatic Steatosis
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PROVIDER: PRJNA545734 | ENA |
REPOSITORIES: ENA
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Project description:Ceramides contribute to the lipotoxicity that underlies diabetes, hepatic steatosis, and heart disease. By genetically engineering mice, we deleted the enzyme dihydroceramide desaturase-1 (DES1) which inserts a conserved double bond into the backbone of ceramides and other predominant sphingolipids. Ablation of DES1 from whole animals, or tissue-specific deletion in the liver, and/or adipose tissue resolved hepatic steatosis and insulin resistance in mice caused by leptin deficiency or obesogenic diets. Mechanistic studies revealed new ceramide actions that promoted lipid uptake and storage and impaired glucose utilization, none of which could be recapitulated by (dihydro)ceramides that lacked the critical double bond. These studies suggest that inhibition of DES1 may provide a means of treating hepatic steatosis and cardiometabolic disorders.
2020-01-30 | GSE132056 | GEO
Project description:Alcohol’s impairment of both hepatic lipid metabolism and insulin resistance (IR) are key drivers of alcoholic steatosis, the initial stage of alcoholic liver disease (ALD). Pharmacologic reduction of lipotoxic ceramide prevents alcoholic steatosis and glucose intolerance in mice, but potential off-target effects limit its strategic utility. Here, we employed a hepatic-specific acid-ceramidase (ASAH) overexpression model to reduce hepatic ceramides in a Lieber-DeCarli model of experimental alcoholic steatosis. We examined effects of alcohol on hepatic lipid metabolism, body composition, energy homeostasis and insulin sensitivity as measured by hyperinsulinemic-euglycemic clamp. Our results demonstrate that hepatic ceramide reduction ameliorates the effects of alcohol on hepatic lipid droplet accumulation by promoting VLDL secretion and lipophagy, the latter of which involves ceramide cross-talk between the lysosomal and lipid droplet compartments. We additionally demonstrate that hepatic ceramide reduction prevents alcohol’s inhibition of hepatic insulin signaling. These effects on the liver are associated with a reduction in oxidative stress markers and are relevant to humans, as we observe peri-lipid droplet ASAH expression in human ALD. Together, our results suggest a potential role for hepatic ceramide inhibition in preventing ALD.
2020-07-08 | GSE139015 | GEO
Project description:Background: Ginseng flower bud (GFB) is a part of ginseng with high content of ginsenosides, the known active components of ginseng. While the scientific data for the pharmacological activity of ginseng roots are accumulating, the therapeutic potential of GFB have been neglected. The current study aimed to examine the therapeutic effect of GFB on hepatic steatosis and to elucidate the underlying mechanisms. Methods: HepG2 cells treated with free fatty acids mixture and hepatocytes isolated from rats after 3 weeks of HFD feeding were used as in vitro models of hepatic steatosis for evaluation of anti-steatotic effect of GFB. The effect of GFB was further investigated in pathological conditions of hepatic steatosis induced by 12 weeks of HFD feeding in C57BL/6J mice. We performed systematical analyses on hepatic gene expression profiles in GFB treated mice. The effect of GFB on the expression profile of selected genes was validated by quantitative PCR. Results: GFB treatment markedly reduced oil red O stained lipid droplets and intracellular triglyceride levels in HepG2 cells and rat hepatocytes. In HFD-fed mice, GFB (500 mg/kg) treatment markedly reduced histological signs of hepatic steatosis and decreased hepatic triglyceride content by 34.1% compared to those of HFD. These changes by GFB treatment were accompanied by improved insulin signaling. Global gene expression analysis revealed that hepatic gene expression in the steatotic liver was reversed by GFB treatment, and the GFB-regulated genes are involved in immune process, insulin response and lipid storage. Conclusion: These findings provide a substantial evidence for the medicinal use of GFB in prevention or treatment of NAFLD through suppression of hepatic inflammation and fatty acid uptake while sensitizing hepatic insulin signaling
2021-01-01 | GSE142059 | GEO
Project description:Enhanced insulin signalling ameliorates C9orf72 hexanucleotide repeat expansion toxicity in Drosophila
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Project description:Liver-specific ceramide reduction alleviates steatosis and insulin resistance in alcohol-fed mice
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Project description:We demonstrated that RORa-deficient staggerer mice (RORasg/sg) fed with a high fat diet (HFD) showed reduced adiposity and hepatic triglyceride levels compared to wild type (WT) littermates and were resistant to the development of hepatic steatosis, adipose-associated inflammation, and insulin resistance. Gene expression profiling showed that many genes involved in triglyceride synthesis and storage, including Cidec, Cidea, and Mogat1, were expressed at much lower levels in liver of RORasg/sg mice. In addition to reduced lipid accumulation, inflammation was greatly diminished in white adipose tissue (WAT) of RORasg/sg mice fed with a HFD. The infiltration of macrophages and the expression of many immune-response and pro-inflammatory genes, including those encoding various chemo/cytokines, toll-like receptors, and TNF signaling proteins, were significantly reduced in RORasg/sg WAT. Moreover, RORasg/sg mice fed with a HFD were protected from the development of insulin resistance. Together, these results indicate that RORa plays a critical role in the regulation of several aspects of metabolic syndrome. Therefore, RORa may provide a novel therapeutic target in the management of obesity and associated metabolic diseases. Liver and white adipose tissue (WAT) total RNAs were purified from 5 WT and 5 RORasg/sg (natural deletion of RORa gene in mice) mice fed with a high fat diet for 6 weeks. Then samples were applied on Agilent mouse genome chip.
2011-04-30 | E-GEOD-23736 | biostudies-arrayexpress
Project description:Individuals with hepatic steatosis often display several metabolic abnormalities including insulin resistance and muscle atrophy. Previously, we found that hepatic steatosis results in an altered hepatokine secretion profile, thereby inducing skeletal muscle insulin resistance via inter-organ crosstalk. In this study, we aimed to investigate whether the altered secretion profile in the state of hepatic steatosis also induces skeletal muscle atrophy via effects on muscle protein turnover. To investigate this, eight-week-old male C57BL/6J mice were fed a chow (4.5% fat) or a high-fat diet (HFD; 45% fat) for 12 weeks to induce hepatic steatosis, after which the livers were excised and cut into ~200 µm slices. Slices were cultured to collect secretion products (conditioned medium; CM). Differentiated L6-GLUT4myc myotubes were incubated with chow or HFD CM to measure glucose uptake. Differentiated C2C12 myotubes were incubated with chow or HFD CM to measure protein synthesis and breakdown, and gene expression via RNA sequencing. Furthermore, proteomics analysis was performed in chow and HFD CM. It was found that HFD CM caused insulin resistance in L6-GLUT4myc myotubes compared with chow CM, as indicated by a blunted insulin-stimulated increase in glucose uptake. Furthermore, protein breakdown was increased in C2C12 cells incubated with HFD CM, while there was no effect on protein synthesis. RNA profiling of C2C12 cells indicated that 197 genes were differentially expressed after incubation with HFD CM, compared with chow CM, and pathway analysis showed that pathways related to anatomical structure and function were enriched. Proteomic analysis of the CM showed that 32 proteins were differentially expressed in HFD CM compared with chow CM. Pathway enrichment analysis indicated that these proteins had important functions with respect to insulin-like Growth Factor transport and uptake, and affect post-translational processes, including protein folding, protein secretion and protein phosphorylation. In conclusion, the results of this study support the hypothesis that secretion products from the liver contribute to the development of muscle atrophy in individuals with hepatic steatosis.
2022-02-17 | PXD027332 | Pride
Project description:Dietary curcumin ameliorates perturbed insulin homeostasis in the diet-induced obese aged mice
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Project description:Cyclic AMP-responsive element-binding protein H (CREBH, encoded by Creb3l3) is a transcription factor that regulates the expression of genes that control lipid and glucose metabolism, as well as inflammation. CREBH is upregulated in the liver under conditions of overnutrition, and mice globally lacking the gene (CREBH-/-) are highly susceptible to diet-induced obesity, insulin resistance (IR) and hepatic steatosis. The net protective effects of CREBH have been attributed in large part to the activities of Fibroblast growth factor (Fgf)-21 (Fgf21), a target gene that promotes weight loss, improves glucose homeostasis and reduces hepatic lipid accumulation. To explore the possibility that activation of the CREBH-Fgf21 axis could ameliorate established effects of high fat feeding, we generated an inducible transgenic hepatocyte-specific CREBH overexpression mouse model (Tg-rtTA). Acute overexpression of CREBH in livers of Tg-rtTA mice effectively reversed diet-induced obesity, IR and hepatic steatosis. These changes were associated with increased activities of thermogenic brown and beige adipose tissues in Tg-rtTA mice, leading to reductions in fat mass, along with enhanced insulin sensitivity and glucose tolerance. Genetically silencing of Fgf21 in Tg-rtTA mice abrogated the CREBH-mediated reductions in body weight loss, but only partially reversed the observed improvements in glucose metabolism. These findings reveal that the protective effects of CREBH activation may be leveraged to mitigate diet-induced obesity and associated metabolic abnormalities in both Fgf21-dependent and -independent pathways.
2021-04-30 | GSE173548 | GEO
Project description:Our data mark GIP as a beneficial immunoregulator during obesity and suggest a novel untapped therapeutic potential for specific targeted GIP analogs. Emerging studies suggest that glucose-dependent insulin tropic polypeptide (GIP) affect obesity-associated inflammation. Yet, whether GIP can directly regulate immune cell activity and the respective metabolic consequences remained unknown. Here, we targeted GIP-receptor-deficiency to immune cells using bone marrow (BM) chimerism approach and the reconstituted chimeric mice were subjected to a high fat diet (HFD) regimen. Mice reconstituted with Gipr-/- BM gained significantly more weight, despite similar food consumption. This was accompanied by increased epididymal adipose tissue (epiWAT) mass, adipocyte hypertrophy, enhanced hepatic steatosis, insulin resistance and significant myelopoiesis in the circulation, epiWAT and inguinal adipose tissue (ingWAT). In accordance these mice also exhibited reduced energy expenditure and ingWAT beiging. Mechanistically, impaired GIP-governed regulation of S100A8/9 in myeloid cells was responsible for the perturbed energy homeostasis, increased insulin resistance and intensified inflammatory response under nutrient overload. Collectively, our results outline a beneficial immunoregulatory role for GIP in immune cells during obesity.
2019-01-02 | GSE109371 | GEO