mRNA Levels Of PPARδ Research Articles

Eicosapentaenoic acid-containing polar lipids from seaweed Susabinori (Pyropia yezoensis) alleviate hepatic steatosis in obese db/db mice

Nonalcoholic fatty liver disease (NAFLD) is emerging as the most common liver disease in industrialized countries. Because hepatic steatosis is an early pathogenesis of NAFLD, the discovery of food components that could ameliorate hepatic steatosis is of interest. Susabinori (Pyropia yezoensis) is recognized as one of the most delicious edible brown algae, and we prepared lipid component of susabinori (SNL), which is rich in eicosapentaenoic acid (EPA)-containing polar lipids. In this study, we tested whether feeding SNL to db/db mice protects them from developing obesity-induced hepatic steatosis. After four weeks of feeding, hepatomegaly, hepatic steatosis, and hepatic injury were markedly alleviated in SNL-fed db/db mice. These effects were partly attributable to the suppression of activities and mRNA expressions of lipogenic enzymes and enhanced levels of adiponectin due to the SNL diet. Additionally, mRNA expression of monocyte chemoattractant protein-1, an inflammatory chemokine, was markedly suppressed, and the mRNA levels of PPARδ, the anti-inflammatory transcription factor, were strongly enhanced in the livers of db/db mice by the SNL diet. We speculate that the development and progression of obesity-induced hepatic steatosis was prevented by the suppression of chronic inflammation due to the combination of bioactivities of EPA, phospholipids, and glycolipids in the SNL diet.

N-Acetylcysteine (NAC) Ameliorates Lipid-Related Metabolic Dysfunction in Bone Marrow Stromal Cells-Derived Adipocytes.

Recent experimental data suggest that fatty acids and lipotoxicity could play a role in the initiation and evolution of metabolic bone diseases such as osteoporosis. A functional bone marrow adipose tissue (BMAT) may provide support to surrounding cells and tissues or may serve as a lipid reservoir that protects skeletal osteoblasts from lipotoxicity. The present study examined the effect of N-acetylcysteine (NAC), a powerful antioxidant and precursor of glutathione, commonly used to treat chronic obstructive pulmonary disease, on triglycerides accumulation in bone marrow stromal cells-derived adipocytes. Quantification of Oil Red O stained cells showed that lipid droplets decreased following NAC treatment. Additionally, exposure of bone marrow stromal cells (HS-5) to NAC increased adiponectin, PPARγ, HO-1, and SIRT-1 and increased beta-oxidation markers such as PPARα and PPARδ mRNA levels. As there is now substantial interest in alternative medicine, the observed therapeutic value of NAC should be taken into consideration in diabetic patients.

Effects of Enzymatically Synthesized Glycogen and Exercise on Abdominal Fat Accumulation in High-Fat Diet-Fed Mice.

The combination of diet and exercise is the first choice for the treatment of obesity and metabolic syndrome. We previously reported that enzymatically synthesized glycogen (ESG) suppresses abdominal fat accumulation in obese rats. However, the effect of the combination of ESG and exercise on abdominal fat accumulation has not yet been investigated. Our goal in this study was therefore to evaluate the effects of dietary ESG and its combination with exercise on abdominal fat accumulation in high-fat diet (HFD)-fed mice. Male ICR mice were assigned to four groups: HFD, HFD containing 20% ESG, HFD with exercise, HFD containing 20% ESG with exercise. Treadmill exercise was performed for 3 wk (25 m/min, 30 min/d, 3 d/wk) after 5-d adaption to running at that speed. Both ESG and exercise significantly reduced the weights of abdominal adipose tissues. In addition, the combination of ESG and exercise significantly suppressed abdominal fat accumulation, suggesting that ESG and exercise showed an additive effect. Exercise significantly increased the mRNA levels of lipid metabolism-related genes such as lipoprotein lipase, peroxisome proliferator-activated receptor delta; factor-delta (PPARδ), carnitin palmitoyltransferase b, adipose triglyceride lipase (ATGL), and uncoupling protein-3 in the gastrocnemius muscle. On the other hand, dietary ESG significantly decreased the mRNA levels of PPARδ and ATGL in the gastrocnemius muscle. These results suggest that the combined treatment of ESG and exercise effectively suppresses abdominal fat accumulation in HFD-fed mice by different mechanisms.

Effect of lactate on intermediary metabolites expression and mitochondrial biogenesis in perfused hearts (864.5)

The aim of this study was to investigate whether lactate would modulates the expression of genes and proteins related to intermediary metabolism and mitochondrial biogenesis, and its impact on cardiac hemodynamic function. The hearts excised from male healthy rats were perfused with or without lactate (20mM) in Krebs‐Henseleit solution along 120 min in a Langendorff apparatus. Hemodynamic values including of perfusion pressure (PP) were acquired during the experiment. PPARδ, PGC1‐α, COXIV, MCT1, MCT4 and LDH mRNA levels were quantified by real time RT‐PCR. Mitochondrial DNA replication was evaluated, comparing COXII mRNA levels, a specific mitochondrial gene.Protein expression was assessed by Western Blot. The activity of hexokinase, lactate dehydrogenase, pyruvate dehydrogenase, citrate synthase, superoxide dismutase (SOD) and catalase were analyzed by colorimetry and spectrophotometry. Significant differences were accepted when P□0.05. The lactate concentration in the heart tissue was elevated in lactate group at 120 min (1.5 ± 1.2 vs. 4.8 ± 0.7 mM). This response was paralleled by a significant increase in mRNA levels of PPARδ (2.3x), PGC1‐α (4.5x), MCT1 (8.0x), MCT4 (4.0x) and LDH (13.7x) when compared to control group. No differences were observed in mitochondrial DNA replication, COX IV mRNA levels and activity of all enzymes, excepted for SOD that was significantly increased in lactate (26.6 ± 12.1 vs 92.3 ± 25.7 µmol/mg/min). PP value reduced after lactate perfusion (74.2 ± 10.3 vs 27.8 ± 6.8 mmHg). Our results provide evidence that lactate up‐regulates the expression of genes involved in cardiac bioenergetics and mitochondrial biogenesis, which might favor cardiac oxygenation.Grant Funding Source: FAPESP

Generation and characterization of a humanized PPARδ mouse model

Humanized mice for the nuclear receptor peroxisome proliferator-activated receptor δ (PPARδ), termed PPARδ knock-in (PPARδ KI) mice, were generated for the investigation of functional differences between mouse and human PPARδ and as tools for early drug efficacy assessment. Human PPARδ function in lipid metabolism was assessed at baseline, after fasting or when challenged with the GW0742 compound in mice fed a chow diet or high-fat diet (HFD). Analysis of PPARδ mRNA levels revealed a hypomorph expression of human PPARδ in liver, macrophages, small intestine and heart, but not in soleus and quadriceps muscles, white adipose tissue and skin. PPARδ KI mice displayed a small decrease of high-density lipoprotein-cholesterol whereas other lipid parameters were unaltered. Plasma metabolic parameters were similar in wild-type and PPARδ KI mice when fed chow or HFD, and following physiological (fasting) and pharmacological (GW0742 compound) activation of PPARδ. Gene expression profiling in liver, soleus muscle and macrophages showed similar gene patterns regulated by mouse and human PPARδ. The anti-inflammatory potential of human PPARδ was also similar to mouse PPARδ in liver and isolated macrophages. These data indicate that human PPARδ can compensate for mouse PPARδ in the regulation of lipid metabolism and inflammation. Overall, this novel PPARδ KI mouse model shows full responsiveness to pharmacological challenge and represents a useful tool for the preclinical assessment of PPARδ activators with species-specific activity.

Haplotypes of the porcine peroxisome proliferator-activated receptor delta gene are associated with backfat thickness.

BackgroundPeroxisome proliferator-activated receptor delta belongs to the nuclear receptor superfamily of ligand-inducible transcription factors. It is a key regulator of lipid metabolism. The peroxisome proliferator-activated receptor delta gene (PPARD) has been assigned to a region on porcine chromosome 7, which harbours a quantitative trait locus for backfat. Thus, PPARD is considered a functional and positional candidate gene for backfat thickness. The purpose of this study was to test this candidate gene hypothesis in a cross of breeds that were highly divergent in lipid deposition characteristics.ResultsScreening for genetic variation in porcine PPARD revealed only silent mutations. Nevertheless, significant associations between PPARD haplotypes and backfat thickness were observed in the F2 generation of the Mangalitsa × Piétrain cross as well as a commercial German Landrace population. Haplotype 5 is associated with increased backfat in F2 Mangalitsa × Piétrain pigs, whereas haplotype 4 is associated with lower backfat thickness in the German Landrace population. Haplotype 4 and 5 carry the same alleles at all but one SNP. Interestingly, the opposite effects of PPARD haplotypes 4 and 5 on backfat thickness are reflected by opposite effects of these two haplotypes on PPAR-δ mRNA levels. Haplotype 4 significantly increases PPAR-δ mRNA levels, whereas haplotype 5 decreases mRNA levels of PPAR-δ.ConclusionThis study provides evidence for an association between PPARD and backfat thickness. The association is substantiated by mRNA quantification. Further studies are required to clarify, whether the observed associations are caused by PPARD or are the result of linkage disequilibrium with a causal variant in a neighbouring gene.

Regulation of skeletal muscle PPARδ mRNA expression in twins

Peroxisome proliferator‐activated receptors (PPARs) are nuclear receptors regulating the expression of genes involved in lipid and glucose metabolism in a complex and to some extent unknown manner. Our aim was to study the impact of different factors on PPARδ mRNA expression in human skeletal muscle on one side, and the impact of PPARδ mRNA expression on these factors, including glucose and lipid metabolism, aerobic capacity, fibre type composition and lipid profile, on the other side. PPARδ mRNA levels were quantified by real‐time PCR in muscle biopsies from 176 young and elderly monozygotic and dizygotic twins. Young twins had significantly increased PPARδ mRNA levels compared with elderly twins. A 2 h hyperinsulinaemic euglycaemic clamp had no significant effect on PPARδ mRNA levels. Biometric models were calculated for basal PPARδ mRNA expression to estimate the degree of genetic versus environmental influence. In both young and elderly twins there was a substantial genetic component influencing basal PPARδ mRNA levels. In a regression model, the muscle PPARδ mRNA expression was correlated to birth weight, central adiposity and age. The level of PPARδ mRNA was also positively correlated with markers for oxidative muscle fibres. However, in this apparently healthy study population, we found no correlations between PPARδ mRNA expression and aerobic capacity, lipid profile or glucose and lipid metabolism. In conclusion, we provide evidence that mRNA expression of PPARδ in human skeletal muscle is under genetic control but also influenced by factors such as age, birth weight and central adiposity.

Modulation of peroxisome proliferator-activated receptor δ and γ transcripts in swine endometrial tissue during early gestation

Recent evidence points to a role for peroxisome proliferator-activated receptors (PPARs) delta and gamma in embryo implantation and survival. In this study, we report the porcine PPARdelta complete coding sequence and mRNA abundance of PPARdelta, PPARgamma1 and gamma2, angiopoietin-like protein 4 (ANGPTL4) and adipocyte determination and differentiation-dependent factor 1 (ADD1) genes in the pregnant sow endometrium. Real-time PCR analysis was used to study the effect of parity (Yorkshire-Landrace multiparous (YL) and nulliparous (YLn)), site of endometrial tissue sampling (between and at embryo attachment sites) in crossbred DurocxYorkshire-Landrace (DYL) sows and stages of pregnancy (non-pregnant, day 15 and day 25 after mating) in Meishan-Landrace (ML) on mRNA levels. Parity effects were observed for PPARdelta, ANGPTL4, and ADD1, with higher mRNA levels in YL than YLn sows. In DYL sows, lower mRNA levels were present at attachment sites compared to between attachment sites for PPARdelta, PPARgamma1, and ANGPTL4. Finally, day 15 pregnant ML sows had lower PPARdelta mRNA levels compared to day 15 cycling ML sows. A significant increase of PPARgamma1 mRNA levels was found on day 25 pregnant ML and DYL sows relative to day 15 ML or DYL pregnant sows. PPARdelta and gamma immunostaining was detected in endometrial tissue of day 15 cycling sows, day 15 and 25 pregnant sows and epithelial cells of day 25 embryos. Collectively, our results suggest a role for PPARdelta, PPARgamma1, and ANGPTL4, but not PPARgamma2, during the peri-implantation period in pregnant sows.

Peroxisome proliferator-activated receptor (PPAR) expression in cultured bovine endometrial cells and response to omega-3 fatty acid, growth hormone and agonist stimulation in relation to series 2 prostaglandin production

The peroxisome proliferator-activated receptors (PPARs) are a family of nuclear transcription factors thought to act as receptors for polyunsaturated fatty acids and to reduce production of series 2 prostaglandins (PG). The objectives of the current study were to characterize PPAR expression and the prostaglandin synthetic activity of cultured bovine endometrial cells in response to known PPAR ligands, as well as to key stimulators and inhibitors of series 2 prostaglandin secretion. PPARα and PPARδ, but not PPARγ, mRNAs are expressed in the BEND cell line regardless of treatment. Under resting conditions, PPARα mRNA levels increase in response to growth hormone ( P < 0.05). In cells stimulated with PdBu, growth hormone depresses PPARα mRNA levels, regardless of whether cells also are treated with IFNτ. In contrast, PPARδ mRNA levels are increased by exposure to PdBu, eicosapentanoic acid and IFNτ, and these effects are additive. PPAR mRNA levels are not predictive of prostaglandin accumulation. Agonist activation of PPARα, PPARδ or PPARγ augments PdBu-induced increases in prostaglandin H synthase-2 mRNA and media accumulation of prostaglandins F 2α and E 2. Treatment with the PPARα/δ agonist carbaprostacyclin, but not the PPARα agonist Wy14643 or PPARγ agonist ciglitazone, completely reverses the IFNτ suppression of prostaglandin synthesis. In conclusion, PPARα and PPARδ function in the response of bovine endometrium to growth hormone and long chain omega-3 polyunsaturated fatty acids.

Nutritional regulation and role of peroxisome proliferator-activated receptor δ in fatty acid catabolism in skeletal muscle

Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors primarily involved in lipid homeostasis. PPARδ displays strong expression in tissues with high lipid metabolism, such as adipose, intestine and muscle. Its role in skeletal muscle remains largely unknown. After a 24-h starvation period, PPARδ mRNA levels are dramatically up-regulated in gastrocnemius muscle of mice and restored to control level upon refeeding. The rise of PPARδ is accompanied by parallel up-regulations of fatty acid translocase/CD36 (FAT/CD36) and heart fatty acid binding protein (H-FABP), while refeeding promotes down-regulation of both genes. To directly access the role of PPARδ in muscle cells, we forced its expression and that of a dominant-negative PPARδ mutant in C2C12 myogenic cells. Differentiated C2C12 cells responds to 2-bromopalmitate or synthetic PPARδ agonist by induction of genes involved in lipid metabolism and increment of fatty acid oxidation. Overexpression of PPARδ enhanced these cellular responses, whereas expression of the dominant-negative mutant exerts opposite effects. These data strongly support a role for PPARδ in the regulation of fatty acid oxidation in skeletal muscle and in adaptive response of this tissue to lipid catabolism.