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PPARalpha-mediated effects of dietary lipids on intestinal barrier gene expression

ABSTRACT: Background: The selective absorption of nutrients and other food constituents in the small intestine is mediated by a group of transport proteins and metabolic enzymes, often collectively called ‘intestinal barrier proteins’. An important receptor that mediates the effects of dietary lipids on gene expression is the peroxisome proliferator-activated receptor alpha (PPARα), which is abundantly expressed in enterocytes. In this study we examined the effects of acute nutritional activation of PPARα on expression of genes encoding intestinal barrier proteins. To this end we used triacylglycerols composed of identical fatty acids in combination with gene expression profiling in wild-type and PPARα-null mice. Treatment with the synthetic PPARα agonist WY14643 served as reference. Results: We identified 74 barrier genes that were PPARα-dependently regulated 6 hours after activation with WY14643. For eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and oleic acid (OA) these numbers were 46, 41, and 19, respectively. The overlap between EPA-, DHA-, and WY14643-regulated genes was considerable, whereas OA treatment showed limited overlap. Functional implications inferred form our data suggested that nutrient-activated PPARα regulated transporters and phase I/II metabolic enzymes were involved in a) fatty acid oxidation, b) cholesterol, glucose, and amino acid transport and metabolism, c) intestinal motility, and d) oxidative stress defense. Conclusion: We identified intestinal barrier genes that were PPARα-dependently regulated after acute activation by fatty acids.This knowledge provides a better understanding of the impact dietary fat has on the barrier function of the gut, identifies PPARα as an important factor controlling this key function, and underscores the importance of PPARα for nutrient-mediated gene regulation in intestine. Keywords: metabolic state analysis

ORGANISM(S): Mus musculus

PROVIDER: GSE9533 | GEO | 2008/05/22

SECONDARY ACCESSION(S): PRJNA103341

REPOSITORIES: GEO

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Project description:Background: The selective absorption of nutrients and other food constituents in the small intestine is mediated by a group of transport proteins and metabolic enzymes, often collectively called âintestinal barrier proteinsâ. An important receptor that mediates the effects of dietary lipids on gene expression is the peroxisome proliferator-activated receptor alpha (PPARÎ±), which is abundantly expressed in enterocytes. In this study we examined the effects of acute nutritional activation of PPARÎ± on expression of genes encoding intestinal barrier proteins. To this end we used triacylglycerols composed of identical fatty acids in combination with gene expression profiling in wild-type and PPARÎ±-null mice. Treatment with the synthetic PPARÎ± agonist WY14643 served as reference. Results: We identified 74 barrier genes that were PPARÎ±-dependently regulated 6 hours after activation with WY14643. For eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and oleic acid (OA) these numbers were 46, 41, and 19, respectively. The overlap between EPA-, DHA-, and WY14643-regulated genes was considerable, whereas OA treatment showed limited overlap. Functional implications inferred form our data suggested that nutrient-activated PPARÎ± regulated transporters and phase I/II metabolic enzymes were involved in a) fatty acid oxidation, b) cholesterol, glucose, and amino acid transport and metabolism, c) intestinal motility, and d) oxidative stress defense. Conclusion: We identified intestinal barrier genes that were PPARÎ±-dependently regulated after acute activation by fatty acids.This knowledge provides a better understanding of the impact dietary fat has on the barrier function of the gut, identifies PPARÎ± as an important factor controlling this key function, and underscores the importance of PPARÎ± for nutrient-mediated gene regulation in intestine. Experiment Overall Design: Pure bred wild-type (129S1/SvImJ) and PPARÎ±-null (129S4/SvJae) mice were treated for 6 hours with the synthetic triacylglycerols triolein [oleic acid (OA, C18:1)], trieicosapentaenoin [eicosapentaenoic acid (EPA, C20:5)] or tridocosahexaenoin [ocosahexaenoic acid (DHA, C22:6)], or the potent PPARÎ± agonist WY14,643. Two weeks before the start of the experiment, mice were put on a modified AIN76A diet, in which corn oil was replaced by olive oil. At the day of the experiment mice were fasted for four hours. At 9 AM mice were dosed by oral gavage with 400 Âµl of a 0.1% WY14643 suspension in 0.5% carboxymethyl cellulose, or 400 Âµl of the synthetic triacylglycerols. Six hours after the gavage the mice were anaesthetized, small intestines were removed, flushed with ice-cold PBS and remaining fat and pancreatic tissue was carefully removed. Total RNA was then isolated. RNA of 4-5 biological replicates was hybridized to Affymetrix 430-2.0 plus arrays. Five microgram total RNA was labelled according to the ENZO-protocol, fragmented and hybridized according to Affymetrix's protocols.

Project description:Dietary n-3 polyunsaturated fatty acids can reduce inflammation via a range of mechanisms. This study tested the effect of dietary eicosapentaenoic acid (EPA) on intestinal inflammation using interleukin-10 gene-deficient (Il10-/-) mice. Methods: At 35 days of age, 12 weaned Il10-/- and 12 C57 mice were randomly assigned to one of two modified AIN-76A diets, supplemented with 3.7% purified ethyl esters of either EPA (n-3) or oleic acid (OA, control). To identify genes relevant to colon inflammation, transcription profiling (microarrays and qRT-PCR) and bioinformatic analyses were used. Results: In this study, dietary EPA reversed the decrease in colon fatty acid Î²-oxidation gene expression observed in OA-fed Il10-/- compared to C57 mice. Il10-/- mice fed the OA diet showed decreased expression of antioxidant enzyme genes, as well as those involved in detoxification of xenobiotics, compared to C57 mice on the same diet. In contrast, dietary EPA increased the expression of these genes in Il10-/- mice. Conclusions: These data indicate that dietary EPA induced endogenous lipid oxidation which might have a potential anti-inflammatory effect on colon tissue. This is supported by the activation of the Ppara gene that regulates the expression of pro-inflammatory and immunomodulatory genes and proteins. Experiment Overall Design: The diet abbreviations EPA, OA, AA and CO used in the sample records Experiment Overall Design: refer to the following : Experiment Overall Design: CO : AIN-76A (control) Experiment Overall Design: OA : AIN-76A (fat-free) + 1% corn oil + 3.7% oleic acid Experiment Overall Design: EPA : AIN-76A (fat-free) + 1% corn oil + 3.7% eicosapentaenoic acid Experiment Overall Design: AA : AIN-76A (fat-free) + 1% corn oil + 3.7% arachidonic acid Experiment Overall Design: Corn oil was supplemented with purified linoleic and alpha-linolenic acid to meet the nutritional requirements of mice for these essential fatty acids. Diets fed for 6 weeks.

Project description:Dietary polyunsaturated fatty acids (PUFA) act as potent natural hypolipidemics and are linked to many health benefits in humans and in animal models. Mice fed long-term a high fat diet, in which medium-chain alpha linoleic acid (ALA) was partially replaced by long-chain docosahexaenoic (DHA) and eicosapentaenoic (EPA) fatty acids, showed reduced accumulation of body fat and prevention of insulin resistance, besides increased mitochondrial beta-oxidation in white adipose tissue and decreased plasma lipids. ALA, EPA and DHA all belong to PUFA of n-3 series. The intestine is a gatekeeper organ for ingested lipids. To examine the potential contribution of the intestine in the beneficial effects of EPA and DHA, this study assessed gene expression changes using whole genome microarray analysis on small intestinal scrapings. The main biological process affected was lipid metabolism. Fatty acid uptake, peroxisomal and mitochondrial beta-oxidation, and omega-oxidation of fatty acids were all increased. Quantitative real time PCR and intestinal fatty acid oxidation measurements ([14C(U)]-palmitate) confirmed significant gene expression differences in a dose-dependent manner. Furthermore, no major changes in the expression of lipid metabolism genes were observed in colonic scrapings. In conclusion, we show that marine n-3 fatty acids regulate small intestinal gene expression patterns. Since this organ contributes significantly to whole organism energy use, this adaptation of the small intestine may contribute to the complex and observed beneficial physiological effects of these natural compounds under conditions that will normally lead to development of obesity and diabetes. Experiment Overall Design: Male 4-month-old C57BL/6J mice were maintained for 4 weeks on semisynthetic high-fat (20% wt/wt) diets differing in the composition of n-3 PUFA. Two isocaloric diets were used (n=12): control sHFf diet which contained flax-seed oil (rich in ALA) as the only lipid source, or the sHFf-F2 diet, which had the same composition except that 44 % of the lipids were replaced by a n-3 PUFA concentrate (EPA&DHA) containing 6 % EPA and 51 % DHA (EPAX 1050TG; EPAX AS, Lysaker, Norway). Quality control of RNA samples showed that four samples did not pass quality thresholds, and these samples were excluded from array analysis (two control small intestine samples and one EPA&DHA small intestine sample). The remaining RNA samples were pooled per tissue per diet group. Thus; the flax-seed (control) array was hybridized with RNA pooled from of 10 mice, the PUFA array was hybridized with RNA pooled from 11 mice.

Project description:Background & Aims: Non-alcoholic fatty liver disease accompanies obesity and is independently associated with cardiovascular disease. Omega-3 fatty acids, such as docosahexaenoic (DHA) and eicosapentaenoic (EPA) acid, reduce the risk of cardiovascular disease due to their anti-inflammatory and hypolipidemic effects. Recent data suggested that metabolic effects of EPA/DHA as marine phospholipids could be stronger than triglycerides (fish oil). We characterised the mechanisms underlying beneficial effects of EPA/DHA phospholipids alone or in combination with antidiabetic drugs on hepatosteatosis in dietary obese mice. Methods: Male C57BL/6N mice were fed for 7 weeks a corn oil-based high-fat diet (cHF) or subjected to cHF-based interventions: (i) cHF with DHA/EPA as phosphatidylcholine-rich concentrate replacing ~10 % of dietary lipids (PC); ii) cHF with a low-dose of thiazolidinedione rosiglitazone (10 mg/kg diet), which retains some of the beneficial effects but also potentiates hepatic lipid accumulation (R); and iii) PC+R. Metabolic profiling together with hepatic gene expression and lipidomic analyses were performed. Results: PC and PC+R prevented weight gain and glucose intolerance induced by cHF, while all interventions reduced abdominal fat and plasma triglycerides. In contrast to R, PC and PC+R lowered hepatic and plasma cholesterol and eliminated hepatosteatosis. Hepatic microarray analysis primarily revealed a complex downregulation of lipogenic and cholesterol biosynthesis pathways by PC. Lipidomic analysis identified arachidonic acid, DHA and EPA in hepatic phosphatidylcholine and phosphatidylethanolamine fractions as the most important variables. Importantly, down-regulation of genes within these pathways was enlarged by phospholipid versus triglyceride forms of EPA/DHA in an independent experiment. Conclusions: Obesity-associated hepatosteatosis and hypercholesterolemia were ameliorated by marine phospholipids in association with a complex inhibition of biosynthetic pathways in liver. Stronger effects of phospholipids versus triglyceride form of EPA/DHA suggest their preferential use in the prevention and possible treatment of obesity-associated metabolic hepatic dysfunctions.

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PPARalpha-mediated effects of dietary lipids on intestinal barrier gene expression

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