Project description:PCSK9 promotes the lysosomal degradation of cell surface LDL receptor (LDLR). We analyzed how excess LDLR generated by PCSK9 deficiency is differently handled in male and female mice to possibly unveil the mechanism leading to the lower efficacy of PCSK9 mAb on LDL-cholesterol levels in women. Analysis of intact or ovariectomized PCSK9 knockout (KO) mice supplemented with placebo or 17β-estradiol (E2) demonstrated that female, but not male mice massively shed the soluble ectodomain of the LDLR in the plasma. Liver-specific PCSK9 KO or alirocumab-treated WT mice exhibit the same pattern. This shedding is distinct from the basal one and is inhibited by ZLDI-8, a metalloprotease inhibitor pointing at ADAM10/ADAM17. In PCSK9 KO female mice, ZLDI- 8 raises by 80 % the LDLR liver content in a few hours. This specific shedding is likely cholesterol-dependent: it is prevented in PCSK9 KO male mice that exhibit low intra-hepatic cholesterol levels without activating SREBP-2, and enhanced by mevalonate or high cholesterol feeding, or by E2 known to stimulate cholesterol synthesis via the estrogen receptor-α. Liver transcriptomics demonstrates that critically low liver cholesterol in ovariectomized female or knockout male mice also hampers the cholesterol-dependent G2/M transition of the cell cycle. Finally, higher levels of shed LDLR were measured in the plasma of women treated with PCSK9 mAb. PCSK9 knockout female mice hormonally sustain cholesterol synthesis and shed excess LDLR, seemingly like women. In contrast, male mice rely on high surface LDLR to replenish their stocks, despite 80 % lower circulating LDL.
Project description:Recent studies have shown that FGF21 is a common target for dietary polyphenol intervention and nutritional restriction. FGF21 is also a newly recognized target of GLP-1R agonists (GLP-1RAs). Here we ask whether hepatic FGF21 is required for dietary polyphenols in exerting their metabolic beneficial effects. Liver-specific FGF21 null mice (lFgf21-/-) were utilized in current study. We found that on chow diet, no appreciable defect on glucose disposal was observed in male or female lFgf21-/- mice, while fat tolerance was impaired in male but not female lFgf21-/- mice, associated with elevated serum TG level, reduced hepatic expression of Ehhadh and Ppargc1. On high-fat-high-fructose (HFHF) diet challenge, Fgf21fl/fl mice but not lFgf21-/- mice exhibited response to curcumin intervention on reducing body weight and serum TG, and on improving fat tolerance. Resveratrol intervention also affected hepatic FGF21 expression and its downstream effectors. Metabolic beneficial effects of resveratrol intervention observed in HFHF diet challenged Fgf21fl/fl mice were either absent or attenuated in lFgf21-/- mice. Thus, hepatic FGF21 is required for curcumin and resveratrol in exerting their metabolic beneficial effect. Recognition that FGF21 is the common target of GLP-1RAs and dietary intervention brings us a novel angle in studying metabolic disease treatment and prevention.
Project description:To determine the effect of consumption of a quercetin-rich diet on obesity and dysregulated hepatic gene expression, C56BL/6J mice were fed for 20 weeks on control or a Western diet high in fat, cholesterol and sucrose, both with or without 0.05% quercetin. Chronic dietary intake of quercetin reduced body weight gain and visceral and liver fat accumulation, and improved hyperglyceamia, hyperinsulinaemia, dyslipidaemia in mice fed a Western-style diet. Feeding a Western-style diet altered expression of genes related to inflammatory responses, lipid metabolism and oxidative phosphorylation in C57BL/6J mice after 20 weeks. The results from exhaustive gene expression analysis showed that quercetin minimally influenced hepatic gene expression in mice fed the Western diet. The gene screening results (GSEA) were consistent with the notion that it did improve mitochondrial function to some extent. Quantitative RT-PCR analysis indicated that quercetin did influence important regulators of fat accumulation and metabolic disorders. Our results suggest that quercetin reduces fat accumulation presumably through decreasing oxidative stress and increasing PPARα expression, and the following improvement of gene expression related to steatosis in the liver. C56BL/6J mice were fed for 20 weeks on AIN93G (con) or a Western diet high in fat, cholesterol and sucrose, both with or without 0.05% quercetin for 20 weeks.
Project description:Background Small intestine and liver greatly contribute to whole body lipid, cholesterol and phospholipid metabolism but to which extent cholesterol and phospholipid handling in these tissues is affected by high fat Western-style obesogenic diets remains to be defined. We therefore quantified cholesterol and phospholipid concentrations in intestine and liver and determined fecal neutral sterol and bile acid excretion in C57Bl/6N mice fed for 12 weeks either a cholesterol-free high carbohydrate control diet or a high fat diet containing 0.03 % (w/w) cholesterol. To identify underlying mechanisms of dietary adaptation in intestine and liver, changes in gene expression were assessed by microarray and qPCR profiling, respectively. Results Animals on high fat diet showed increased plasma cholesterol levels, associated with the higher dietary cholesterol supply, yet, significantly reduced cholesterol levels were found in intestine and liver. Transcript profiling revealed evidence that expression of numerous genes involved in cholesterol synthesis and uptake via LDL, but also in phospholipid metabolism, underwent compensatory regulations in both tissues. Alterations in glycerophospholipid metabolism were confirmed at the metabolite level by phospolipid profiling via mass spectrometry. Conclusions Our findings suggest that intestine and liver react to a high dietary fat intake by an activation of de novo cholesterol synthesis and other cholesterol-saving mechanisms, as well as with major changes in phospholipid metabolism, to accommodate to the fat load. The proximal part of the intestine of mice fed either a control or a high fat diet were analyzed. 5 replicates each.
Project description:Matrin-3 is an RNA-binding protein involved in the pathogenesis of human diseases. Here we examined the hepatic transcriptome of chow-diet fed mice. Bulk RNA-seq and bioinformatics analysis identified 646 and 145 differentially expressed genes (Padj < 0.05), respectively in the livers of female and male matrin-3 LKO mice. Enrichr analysis of these DEGs revealed several common Hallmark terms including cholesterol homeostasis, fatty acid metabolism, xenobiotic metabolism, and epithelial mesenchymal transition between female and male mice. Our data demonstrated that liver-specific matrin-3 deficiency re-programs the hepatic transcriptome in the liver of chow diet-fed mice.
Project description:De novo lipogenesis (DNL) has been implicated in the development and progression of hepatic liver steatosis. Hepatic DNL is strongly influenced by dietary macronutrient composition with diets high in carbohydrate increasing DNL and diets high in fat decreasing DNL. The enzymes in the core DNL pathway have been well characterised however less is known about proteins that play accessory or regulatory roles in DNL. In the current study, we associate measured rates of hepatic DNL and liver fat content with abundance of liver proteins from liquid chromatography mass spectrometry in mice to identify known and uncharacterised proteins that may have a role in DNL. Male C57BL/6J mice were fed either a standard chow diet a semi-purified high starch diet or a high fat diet. Both semi-purified diets resulted in increased body weight, fat mass and liver triglyceride content compared to chow-fed mice while hepatic DNL was increased in the high starch fed mice and decreased in the high fat fed mice. Proteomic analysis was carried out on the livers of these mice and proteins were identified that associated with either the rate of DNL or triglyceride content in the liver. There was no overlap between DNL and triglyceride associated proteins. We identify novel proteins associated with DNL that are involved in taurine metabolism, which suggests a link between these pathways. Further analysis identified proteins that are differentially regulated when comparing a non-purified chow diet to either of the semi-purified diets to provide a set of proteins that are regulated by the degree of dietary complexity alone. Finally, we compared the liver proteome between 4 week-fed and 30-week diet-fed mice and found remarkable similarity suggesting that the majority of diet-regulated proteins change early in response to differing dietary components.
Project description:We investigated parent-of-origin and allele-specific expression effects on obesity and hepatic gene expression in reciprocal crosses between the Berlin Fat Mouse Inbred line (BFMI) and C57Bl/6NCrl (B6N). We sequenced mRNA extracted from liver tissue of 10 M. Musculus individuals. 4 liver samples were collected from 10 week old inbred strains (1 male and 1 female Berlin Fat Mouse Inbred line (BFMI), 1 male and 1 female C57Bl/6NCrl (B6N)) and 6 liver samples collected from 10 week old F1 males using a reciprocal cross design (3 paternal BFMI (patBFMI) vs 3 maternal BFMI (matBFMI)).
Project description:The objective of this study was to determine the effect of dieldrin on the hepatic proteome in the zebrafish liver following dietary exposure. Female zebrafish were fed a control dose or one of three doses of DLD-contaminated food pellets over 21 days.
Project description:Dietary flavonoids are supposed to be protective against cardiovascular diseases (CVD). Elevated circulating lipid levels and hepatic lipid accumulation are known risk factors for CVD. We investigated the effects and underlying molecular mechanisms of the flavonoid quercetin on hepatic lipid metabolism in mice with diet induced body weight gain and hepatic lipid accumulation. Adult male mice received a high-fat diet without or with supplementation of 0.33% (w/w) quercetin for 12 weeks. Body weight gain was 29% lower in quercetin-fed mice (p<0.01), while the energy intake was not significantly different. Quercetin supplementation reduced hepatic lipid accumulation with 71% (p<0.05). 1H nuclear magnetic resonance serum lipid profiling revealed that the supplementation lowered serum lipids (p<0.0001). Global gene expression profiling of liver showed that key target genes of the transcription factor Constitutive androstane receptor (Car; official symbol Nr1i3) were regulated, in particular Cytochrome P450 2b (Cyp2b) genes. Quercetin can decrease high-fat diet induced body weight gain, hepatic lipid accumulation and serum lipid levels, which might be explained by the regulation of Cytochrome P450 genes under transcriptional control of CAR, an effect which is likely dependent on dietary background. Liver samples were obtained from 24 C57BL/6J male adult mice. All mice started with a three week adaptation phase, in which they were fed a normal-fat diet. During the intervention of 12 weeks, the mice received a high-fat diet without (HF) or with supplementation of 0.33% (w/w) quercetin (HF-Q). Based on visual inspection, three arrays lacked homogenous hybridization and were therefore excluded.
Project description:We found that global heterozygous midnolin knockout attenuated the severity of nonalnonalcoholic fatty liver disease (NAFLD) in mice fed a Western-style diet, high in fat, cholesterol, and fructose. This attenuation in disease was associated with significantly reduced levels of large lipid droplets, hepatic free cholesterol, and serum LDL, with significantly differential gene expression involved in cholesterol/lipid metabolism.