Increase In Peroxisome Proliferator-activated Receptor Research Articles

Aspergillus cristatus attenuates DSS-induced intestinal barrier damage through reducing the oxidative stress, regulating short-chain fatty acid and inhibiting MAPK signaling pathways.

Probiotics are regarded as a promising strategy for relieving colitis caused by dextran sulfate sodium (DSS). One of the dominant probiotic fungi in Fuzhuan brick tea is identified as Aspergillus cristatus, but whether it can effectively improve colitis remains poorly understood. Here, the improving effect of A. cristatus on colitis was investigated. Our results showed that A. cristatus intervention prominently alleviated gut damage as evidenced by the inhibition of shortened colon length, goblet cell depletion, and histological injury. Mechanistically, after administration with low concentrations of A. cristatus H-1 and A. cristatus S-6, the expression of interleukin-6, tumor necrosis factor-α, interleukin-1β, nitric oxide, and malondialdehyde were significantly downregulated, and the content of glutathione, catalase, interleukin-10, immunoglobulin G, claudin-1, occludin, and zonula occludens-1 were effectively upregulated. More importantly, live A. cristatus supplementation lightened DSS-induced gut barrier damage by suppressing activation of the mitogen-activated protein kinase (MAPK) signaling pathway, increasing the synthesis of short-chain fatty acids (SCFAs) and stimulating the increase in peroxisomeproliferator-activated receptor γ expression. Together, A. cristatus can attenuate DSS-induced intestinal barrier damage through reducing the oxidative stress, regulating SCFA and inhibiting MAPK signaling pathways (P38/JNK/ERK). Our findings indicate that A. cristatus replenishment has potential as a new probiotic fungi to reduce DSS-induced colitis. © 2022 Society of Chemical Industry.

Myoblast-derived exosomes promote the repair and regeneration of injured skeletal muscle in mice.

When skeletal muscle is damaged, satellite cells (SCs) are activated to proliferate rapidly and fuse with the damaged muscle fibers to form new muscle fibers, thereby promoting muscle growth and remodeling and repair of trauma. Exosomes from differentiating human skeletal muscle cells trigger myogenesis of stem cells and provide biochemical cues for skeletal muscle regeneration. Therefore, we hypothesized that, when muscles are injured, myoblast-derived exosomes may regulate muscle repair and regeneration. Here, we investigated the underlying mechanism by applying C2C12-derived exosomes to injured mouse skeletal muscles. The expression levels of skeletal muscle regeneration factors paired box 7 and lipid-promoting factor peroxisome proliferator-activated receptor γ were upregulated, whereas the expression levels of fibrosis factors collagen-1 and α-smooth muscle actin decreased. The expression of proliferating cell nuclear antigen was elevated after applying C2C12-derived exosomes to SCs. Application of C2C12-derived exosomes to fibro-adipogenic progenitors resulted in an increase in peroxisome proliferator-activated receptor γ expression and adipogenesis capacity, whereas α-smooth muscle actin expression and fibrosis capacity decreased. Analysis of the transcriptome and proteome of SCs after treatment with exosomes showed the involvement of multiple biological processes, including proliferation and differentiation of SCs, muscle regeneration, skeletal muscle atrophy, and the inflammatory response after muscle injury. Hence, our data suggest that C2C12-derived exosomes can promote the regeneration of skeletal muscle fibers, accelerate the production of fat from damaged muscles, inhibit the fibrosis of damaged muscles, and accelerate injury repair, which is related to exosome-mediated regulation of the proliferation of SCs, differentiation of fibro-adipogenic progenitors, and modulation of SC mRNA expression and protein formation and decomposition.

Immune Cell Regulation by Macrophage Derived Small Extracellular Vesicles in Pain

BackgroundDevelopment of chronic pain is related to aberrant neuroimmune signaling. Small extracellular vesicles (sEVs) are 30‐150nm size particles of endosomal origin. They play an important role in neuroimmune crosstalk facilitating transfer of biomolecular cargo between cells. Our studies show that sEVs from RAW 264.7 macrophage cells can be therapeutic or prophylactic in mouse model of inflammatory pain. We investigated the mechanistic basis of how sEVs from lipopolysaccharide (LPS) stimulated (Exo+) and unstimulated (Exo‐) cells impact primary glial cells, dendritic cells (DCs) and adaptive immune cells such as CD4+T cells. We hypothesize that macrophage derived sEVs can potentiate T cell activation directly, or indirectly by the upregulation of major histocompatibility complex‐II (MHC‐II) and co‐stimulatory molecules on DCs, attenuating pain hypersensitivity. We will also test if sEVs confer protection to glial cells in the context of inflammation.MethodsPrimary mouse DCs, microglia and astrocytes were incubated with 1µg Exo‐/+sEVs for 24 hours. Splenocyte derived CD4+ T cells were treated with 0.1ug Exo‐/+ sEVs for 72 hours. Flow cytometry and qPCR was used for analysis.ResultsCharacterization of RAW sEVs showed the presence of sEV markers CD81 and Alix. sEV treatment of DCs resulted in an increase in CD80+/CD86+ MHCIIhiCD11c+/hi DCs. Treatment of CD4+T cells with sEVs increased Tgf‐βexpression. Pretreatment with Exo+ sEV increased Tfgf‐β expression in glial cells upon LPS stimulation. An increase in PPAR (Peroxisome proliferator activated receptor) expression was observed upon sEV treatment of glial cells.ConclusionUpregulation of MHC‐II and costimulatory molecules on DCs as well as PPAR upregulation in glial cells upon sEVs treatment indicates that sEVs from RAW 264.7 cells can modulate immune response. These results indicate sEVs modulate innate cells such as microglia and DCs and adaptive immune cells such as CD4+ T cells may contribute to therapeutic effect in attenuating chronic pain.

Diagnostic value of PPAR\u03b4 and miRNA-17 expression levels in patients with non-small cell lung cancer

The PPARδ gene codes protein that belongs to the peroxisome proliferator-activated receptor (PPAR) family engaged in a variety of biological processes, including carcinogenesis. Specific biological and clinical roles of PPARδ in non-small cell lung cancer (NSCLC) is not fully explained. The association of PPARα with miRNA regulators (e.g. miRNA-17) has been documented, suggesting the existence of a functional relationship of all PPARs with epigenetic regulation. The aim of the study was to determine the PPARδ and miR-17 expression profiles in NSCLC and to assess their diagnostic value in lung carcinogenesis. PPARδ and miR-17 expressions was assessed by qPCR in NSCLC tissue samples (n = 26) and corresponding macroscopically unchanged lung tissue samples adjacent to the primary lesions served as control (n = 26). PPARδ and miR-17 expression were significantly lower in NSCLC than in the control (p = 0.0001 and p = 0.0178; respectively). A receiver operating characteristic (ROC) curve analysis demonstrated the diagnostic potential in discriminating NSCLC from the control with an area under the curve (AUC) of 0.914 for PPARδ and 0.692 for miR-17. Significant increase in PPARδ expression in the control for current smokers vs. former smokers (p = 0.0200) and increase in miR-17 expression in control tissue adjacent to adenocarcinoma subtype (p = 0.0422) were observed. Overexpression of miR-17 was observed at an early stage of lung carcinogenesis, which may suggest that it acts as a putative oncomiR. PPARδ and miR-17 may be markers differentiating tumour tissue from surgical margin and miR-17 may have diagnostic role in NSCLC histotypes differentiation.

Insufficient liver maturation affects murine early postnatal hair cycle

Abnormal hair loss results from a variety of factors, such as metabolic dysfunctions, immunodeficiency, and environmental stressors. Here, we report that mutant mice having defects in liver function, develop alopecia. We have shown previously that in mice lacking a Cnot3 gene, which encodes an essential component of the CCR4-NOT deadenylase complex in liver (Cnot3-LKO mice), the liver does not mature properly, resulting in various pathologies such as hepatitis, hepatic necrosis, and anemia. Unexpectedly, Cnot3-LKO mice start to lose hair around postnatal day 17 (P17). The region of hair loss expands all across their backs and symptoms persist until around P28-30. Afterward, hair re-grows, and Cnot3-LKO mice show complete hair recovery by P40. The phenotype is dependent on mouse genotype, indicating that hair follicle morphogenesis and cycling are influenced by abnormal liver development. By performing histological, quantitative PCR, and immunoblot analyses, we detected sebaceous gland (SG) hypertrophy accompanied by an increase of peroxisome proliferator-activated receptor γ (PPARγ). Collectively, these findings suggest that paracrine signaling related to liver function influences hair growth, at least in part, by altering lipid metabolism.

An In Vitro Study on Mitochondrial Compensatory Response Induced by Gliadin Peptides in Caco-2 Cells.

Dietary gliadin may show a broad spectrum of toxicity. The interplay between mitochondria and gliadin-induced oxidative stress has not been thoroughly examined in the intestinal epithelium. In this kinetic study, Caco-2 cells were exposed for 24 h to pepsin-trypsin-digested gliadin, alone or in combination with the antioxidant 2,6-di-tbutyl-p-cresol (BHT), and the effects on mitochondrial biogenesis and mtDNA were studied. Cells ability to recover from stress was determined after 24 h and 48 h of incubation in the culture medium. Gliadin-induced oxidative stress evoked a compensatory response. The stressor triggered a rapid and significant increase of Peroxisome proliferator-activated receptor γ coactivator-1alpha (PGC-1α) and Peroxiredoxin III (PrxIII) proteins, and mtDNA amount. As for the effects of gliadin on mtDNA integrity, strand breaks, abasic sites, and modified bases were analyzed in three mtDNA regions. D-loop appeared a more fragile target than Ori-L and ND1/ND2. The temporal trend of the damage at D-loop paralleled that of the amount of mtDNA. Overall, a trend toward control values was shown 48 h after gliadin exposure. Finally, BHT was able to counteract the effects of gliadin. Results from this study highlighted the effects of gliadin-induced oxidative stress on mitochondria, providing valuable evidence that might improve the knowledge of the pathophysiology of gluten-related disorders.

Triterpenoids from Hibiscus sabdariffa L.with PPARδ/γ Dual Agonist Action: In Vivo, In Vitro and In Silico Studies.

Hibiscus sabdariffa is a medicinal plant consumed as a diuretic and anti-obesity remedy. Several pharmacological studies have shown its beneficial effects in metabolism. Peroxisome proliferator-activated receptors δ and γ may play a role in the actions of H. sabdariffa. These nuclear receptors regulate lipid and glucose metabolism and are therapeutic targets for type 2 diabetes. This research aimed to perform a phytochemical study guided by a bioassay from H. sabdariffa to identify compounds with peroxisome proliferator-activated receptor δ and peroxisome proliferator-activated receptor γ agonist activity, supported by messenger ribonucleic acid expression, molecular docking, lipid accumulation, and an antihyperglycemic effect. An oral glucose tolerance test in mice with the aqueous extract of H. sabdariffa and the dichloromethane extract of H.sabdariffa was performed. The dichloromethane extract of H. sabdariffa exhibited an antihyperglycemic effect. The dichloromethane extract of H. sabdariffa was fractioned, and four fractions were evaluated in 3T3-L1 adipocytes on peroxisome proliferator-activated receptor δ, peroxisome proliferator-activated receptor γ, fatty acid transporter protein, and glucose transporter type 4 messenger ribonucleic acid expression. Fraction F3 exhibited peroxisome proliferator-activated receptor δ/γ dual agonist activity, and a further fractionation yielded two subfractions, F3-1 and F3-2, which also increased peroxisome proliferator-activated receptor δ and peroxisome proliferator-activated receptor γ expression. Subfractions were analyzed by GC/MS. The main compounds identified in F3-1 were linoleic acid, oleic acid, and palmitic acid, while in F3-2, the main compounds identified were α-amyrin and lupeol. These molecules were subjected to molecular docking analysis. α-Amyrin and lupeol showed the highest affinity. Moreover, both produced an increase in peroxisome proliferator-activated receptor δ, peroxisome proliferator-activated receptor γ, fatty acid transporter protein, and glucose transporter type 4 expression. Additionally, α-amyrin and lupeol decreased lipid accumulation in 3T3-L1 adipocytes and blood glucose in mice. Until now, α-amyrin and lupeol have not been reported with activity on peroxisome proliferator-activated receptors. This study provides evidence that α-amyrin and lupeol possess antidiabetic effects through a peroxisome proliferator-activated receptor δ/γ dual agonist action.

Regulation of PKCβ levels and autophagy by PML is essential for high-glucose-dependent mesenchymal stem cell adipogenesis

Obesity is a complex disease characterized by the accumulation of excess body fat, which is caused by an increase in adipose cell size and number. The major source of adipocytes comes from mesenchymal stem cells (MSCs), although their roles in obesity remain unclear. An understanding of the mechanisms, regulation, and outcomes of adipogenesis is crucial for the development of new treatments for obesity-related diseases. Recently an unexpected role for the tumor suppressor promyelocytic leukemia protein (PML) in hematopoietic stem cell biology and metabolism regulation has come to light, but its role in MSC biology remains unknown. Here, we investigated the molecular pathway underlying the role of PML in the control of adipogenic MSC differentiation. Muscle-derived stem cells (MDSCs) and adipose-derived stem cells (ADSCs) obtained from mice and voluntary patients (as a source of MSCs) were cultured in the presence of high glucose (HG) concentration, a nutrient stress condition known to promote MSCs differentiation into mature adipocytes and the adipogenic potential of PML was assessed. PML is essential for a correct HG-dependent adipogenic differentiation, and the enhancement of PML levels is fundamental during adipogenesis. Increased PML expression enables the upregulation of protein kinase Cβ (PKCβ), which, in turn, by controlling autophagy levels permits an increase in peroxisome proliferator-activated receptor γ (PPARγ) that leads the adipogenic differentiation. Therefore, genetic and pharmacological depletion of PML prevents PKCβ expression, and by increasing autophagy levels, impairs the MSCs adipogenic differentiation. Human ADSCs isolated from overweight patients displayed increased PML and PKCβ levels compared to those found in normal weight individuals, indicating that the PML-PKCβ pathway is directly involved in the enhancement of adipogenesis and human metabolism. The new link found among PML, PKCβ, and autophagy opens new therapeutic avenues for diseases characterized by an imbalance in the MSCs differentiation process, such as metabolic syndromes and cancer.

Pentose Phosphate Shunt Modulates Reactive Oxygen Species and Nitric Oxide Production Controlling Trypanosoma cruzi in Macrophages

Metabolism provides substrates for reactive oxygen species (ROS) and nitric oxide (NO) generation, which are a part of the macrophage (Mφ) anti-microbial response. Mφs infected with Trypanosoma cruzi (Tc) produce insufficient levels of oxidative species and lower levels of glycolysis compared to classical Mφs. How Mφs fail to elicit a potent ROS/NO response during infection and its link to glycolysis is unknown. Herein, we evaluated for ROS, NO, and cytokine production in the presence of metabolic modulators of glycolysis and the Krebs cycle. Metabolic status was analyzed by Seahorse Flux Analyzer and mass spectrometry and validated by RNAi. Tc infection of RAW264.7 or bone marrow-derived Mφs elicited a substantial increase in peroxisome proliferator-activated receptor (PPAR)-α expression and pro-inflammatory cytokine release, and moderate levels of ROS/NO by 18 h. Interferon (IFN)-γ addition enhanced the Tc-induced ROS/NO release and shut down mitochondrial respiration to the levels noted in classical Mφs. Inhibition of PPAR-α attenuated the ROS/NO response and was insufficient for complete metabolic shift. Deprivation of glucose and inhibition of pyruvate transport showed that Krebs cycle and glycolysis support ROS/NO generation in Tc + IFN-γ stimulated Mφs. Metabolic profiling and RNAi studies showed that glycolysis-pentose phosphate pathway (PPP) at 6-phosphogluconate dehydrogenase was essential for ROS/NO response and control of parasite replication in Mφ. We conclude that IFN-γ, but not inhibition of PPAR-α, supports metabolic upregulation of glycolytic-PPP for eliciting potent ROS/NO response in Tc-infected Mφs. Chemical analogs enhancing the glucose-PPP will be beneficial in controlling Tc replication and dissemination by Mφs.

Tadehaginosides A-J, Phenylpropanoid Glucosides from Tadehagi triquetrum, Enhance Glucose Uptake via the Upregulation of PPARγ and GLUT-4 in C2C12 Myotubes.

Ten new phenylpropanoid glucosides, tadehaginosides A-J (1-10), and the known compound tadehaginoside (11) were obtained from Tadehagi triquetrum. These phenylpropanoid glucosides were structurally characterized through extensive physical and chemical analyses. Compounds 1 and 2 represent the first set of dimeric derivatives of tadehaginoside with an unusual bicyclo[2.2.2]octene skeleton, whereas compounds 3 and 4 contain a unique cyclobutane basic core in their carbon scaffolds. The effects of these compounds on glucose uptake in C2C12 myotubes were evaluated. Compounds 3-11, particularly 4, significantly increased the basal and insulin-elicited glucose uptake. The results from molecular docking, luciferase analyses, and ELISA indicated that the increased glucose uptake may be due to increases in peroxisome proliferator-activated receptor γ (PPARγ) activity and glucose transporter-4 (GLUT-4) expression. These results indicate that the isolated phenylpropanoid glucosides, particularly compound 4, have the potential to be developed into antidiabetic compounds.

Dietary cholesterol induces hepatic inflammation and blunts mitochondrial function in the liver of high-fat-fed mice

The present study investigated the role of dietary cholesterol and fat in the development of nonalcoholic fatty liver disease, a common liver disease in metabolic disorders. Mice were fed a diet of regular chow (CH), chow supplemented with 0.2% w/w cholesterol (CHC), high fat (HF, 45kcal%) or HF with cholesterol (HFC) for 17weeks. While both HF and HFC groups displayed hepatic steatosis and metabolic syndrome, only HFC group developed the phenotype of liver injury, as indicated by an increase in plasma level of alanine transaminase (ALT, by 50–80%). There were ~2-fold increases in mRNA expression of tumor necrosis factor α, interleukin 1β and monocyte chemotactic protein 1 in the liver of HFC-fed mice (vs. HF) but no endoplasmic reticulum stress or oxidative stress was observed. Furthermore, cholesterol suppressed HF-induced increase of peroxisome proliferator-activated receptor γ coactivator 1α and mitochondrial transcription factor A expression and blunted fatty acid oxidation. Interestingly, after switching HFC to HF diet for 5weeks, the increases in plasma ALT and liver inflammatory markers were abolished but the blunted of mitochondrial function remained. These findings suggest that cholesterol plays a critical role in the conversion of a simple fatty liver toward nonalcoholic steatohepatitis possibly by activation of inflammatory pathways together with retarded mitochondrial function.

Inhibition of cytochrome P4502E1 by chlormethiazole attenuated acute ethanol-induced fatty liver

Cytochrome P4502E1 (CYP2E1) has been demonstrated to play crucial roles in chronic ethanol-induced fatty liver, while its role in acute ethanol-induced fatty liver remains unclear. The current study was designed to evaluate the effects of chlormethiazole (CMZ), a specific inhibitor of CYP2E1, on acute ethanol-induced fatty liver, and to explore the mechanisms. Mice were pretreated with single dose of CMZ (50mg/kg body weight) by intraperitoneal injection or equal volume of saline, and then exposed to three doses of ethanol (5g/kg body weight, 25%, w/v) by gavage with 12h intervals. The mice were sacrificed at 4h after the last ethanol dosing. It was found that CMZ significantly attenuated acute ethanol-induced increase of the hepatic and serum triglyceride levels, and reduced fat droplets accumulation in mice liver. Acute ethanol-induced increase of the hepatic malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) levels (two biomarkers for oxidative stress) and decrease of glutathione (GSH) level was significantly suppressed by CMZ. CMZ also suppressed ethanol-induced decline of serum adiponectin level, but did not significantly affect the serum tumor necrosis factor-α (TNF-α) and ethanol levels. Furthermore, a significant decline of p62 protein level was observed in CMZ/ethanol group mice liver compared with that of the ethanol group mice. However, acute ethanol-induced increase of peroxisome proliferator-activated receptor α (PPAR-α) protein level was suppressed by CMZ, while the protein levels of sterol regulatory element-binding protein-1c (SREBP-1) and diacylglycerol acyltransferase 2 (DGAT2) were not significantly affected by ethanol or CMZ. Collectively, the results of the current study demonstrated that CMZ could effectively attenuate acute ethanol-induced fatty liver possibly by suppressing oxidative stress and adiponectin decline, and activating autophagy, which suggest that CYP2E1 might also play important roles in acute ethanol-induced fatty liver.

Transgenic Muscle-Specific Nor-1 Expression Regulates Multiple Pathways That Effect Adiposity, Metabolism, and Endurance

The mRNA encoding Nor-1/NR4A3 is rapidly and strikingly induced by β2-adrenergic signaling in glycolytic and oxidative skeletal muscle. In skeletal muscle cells, Nor-1 expression is important for the regulation of oxidative metabolism. Transgenic skeletal muscle-specific expression of activated Nor-1 resulted in the acquisition of an endurance phenotype, an increase in type IIA/X oxidative muscle fibers, and increased numbers of mitochondria. In the current study, we used dual-energy x-ray absorptiometry and magnetic resonance imaging analysis to demonstrate decreased adiposity in transgenic (Tg) Nor-1 mice relative to that in wild-type littermates. Furthermore, the Tg-Nor-1 mice were resistant to diet-induced weight gain and maintained fasting glucose at normoglycemic levels. Expression profiling and RT-quantitative PCR analysis revealed significant increases in genes involved in glycolysis, the tricarboxylic acid cycle, oxidative phosphorylation, fatty acid oxidation, and glycogen synthesis, in concordance with the lean phenotype. Moreover, expression profiling identified several Z-disc and sarcomeric binding proteins that modulate fiber type phenotype and endurance, eg, α-actinin-3. In addition, we demonstrated that the Tg-Nor-1 mouse line has significantly higher glycogen content in skeletal muscle relative to that in wild-type littermates. Finally, we identified a decreased NAD(+)/NADH ratio with a concordant increase in peroxisome proliferator-activated receptor γ coactivator-1α1 protein/mRNA expression. Increased NADH was associated with an induction of the genes involved in the malate-aspartate shuttle and a decrease in the glycerol 3-phosphate shuttle, which maximizes aerobic ATP production. In conclusion, skeletal muscle-specific Nor-1 expression regulates genes and pathways that regulate adiposity, muscle fiber type metabolic capacity, and endurance.

Similar skeletal muscle angiogenic and mitochondrial signalling following 8 weeks of endurance exercise in mice: discontinuous versus continuous training

Little is known about skeletal muscle adaptation to discontinuous endurance training. It has been suggested that accumulating 30 min of endurance exercise daily may result in similar adaptations in the working muscle to a 30 min exercise bout. The purposes of the present investigation, therefore, were to conduct an 8 week continuous or discontinuous endurance training regimen and determine the following: (i) whether treadmill exercise capacity differs between the two training regimens; and (ii) whether the angiogenic and mitochondrial signalling pathways are differentially activated in the two training regimens. Twenty-four young adult male FVB/NJ mice were randomized into the following three groups: control; continuous treadmill endurance training for 30 min five times a week; or discontinuous treadmill endurance training for a total of 30 min five times per week for three 10 min intervals with 2 h rest between intervals. After the intervention, endurance capacity increased by 60% (P < 0.001) in both exercise groups compared to control animals. For the quadriceps muscle, anti-angiogenic regulators (thrombospondin-1 and ADAMTS1) were reduced by 50-70% (P < 0.001) with either exercise regimen. In addition, phosphorylation of p38 mitogen-activated protein kinase signalling increased by 50-300% (P < 0.001), which corresponded to an increase in peroxisome proliferator-activated receptor γ coactivator 1 β (PGC-1β) protein expression. These findings suggest that accumulating 30 min of endurance exercise in 10 min sessions results in similar endurance training adaptations in skeletal muscle to a 30 min exercise bout.

Inhibitive Effects of Mulberry Leaf-Related Extracts on Cell Adhesion and Inflammatory Response in Human Aortic Endothelial Cells

Effects of mulberry leaf-related extracts (MLREs) on hydrogen peroxide-induced DNA damage in human lymphocytes and on inflammatory signaling pathways in human aortic endothelial cells (HAECs) were studied. The tested MLREs were rich in flavonols, especially bombyx faces tea (BT) in quercetin and kaempferol. Polyphenols, flavonoids, and anthocyanidin also abounded in BT. The best trolox equivalent antioxidant capacity (TEAC) was generated from the acidic methanolic extracts of BT. Acidic methanolic and water extracts of mulberry leaf tea (MT), mulberry leaf (M), and BT significantly inhibited DNA oxidative damage to lymphocytes based on the comet assay as compared to the H2O2-treated group. TNF-α-induced monocyte-endothelial cell adhesion was significantly suppressed by MLREs. Additionally, nuclear factor kappa B (NF-κB) expression was significantly reduced by BT and MT. Significant reductions were also observed in both NF-κB and activator protein (AP)-1 DNA binding by MLREs. Significant increases in peroxisome proliferator-activated receptor (PPAR) α and γ DNA binding by MLREs were also detected in M and MT extracts, but no evidence for PPAR α DNA binding in 50 μg/mL MT extract was found. Apparently, MLREs can provide distinct cytoprotective mechanisms that may contribute to its putative beneficial effects on suppressing endothelial responses to cytokines during inflammation.

Increase of Peroxisome Proliferator-activated Receptor δ (PPARδ) by Digoxin to Improve Lipid Metabolism in the Heart of Diabetic Rats

Increase of peroxisome proliferator-activated receptor δ (PPARδ) expression by digoxin in the heart of diabetic rats has been documented. The present study investigated the mediation of PPARδ in lipid metabolism improved by digoxin in the heart of diabetic rats and in the hyperglycemia-treated cardiomyocytes using the primary cultured cardiomyocytes from neonatal rat. The lipid deposition within the heart section was assessed in diabetic rats by oil red O staining. The fatty acid oxidation genes in cardiomyocytes were also examined. Inhibitor of calcium ions and siRNA-PPARδ were employed to investigate the potential mechanisms. After a 20-day digoxin treatment, the PPARδ expression was elevated in hearts of diabetic rats while the cardiac lipid deposition was reduced. In neonatal cardiomyocytes, digoxin also caused an increase in expressions of PPARδ and fatty acid oxidation genes. But both actions of digoxin were blocked by BAPTA-AM to chelate calcium ions and by siRNA-PPARδ in cardiomyocytes. The obtained results show that increase of PPARδ by digoxin is related to regulation of fatty acid oxidation genes in cardiac cells mediated by calcium-triggered signals.

Antioxidant Supplementation Reduces Skeletal Muscle Mitochondrial Biogenesis

Exercise increases the production of reactive oxygen species (ROS) in skeletal muscle, and athletes often consume antioxidant supplements in the belief they will attenuate ROS-related muscle damage and fatigue during exercise. However, exercise-induced ROS may regulate beneficial skeletal muscle adaptations, such as increased mitochondrial biogenesis. We therefore investigated the effects of long-term antioxidant supplementation with vitamin E and α-lipoic acid on changes in markers of mitochondrial biogenesis in the skeletal muscle of exercise-trained and sedentary rats. Male Wistar rats were divided into four groups: 1) sedentary control diet, 2) sedentary antioxidant diet, 3) exercise control diet, and 4) exercise antioxidant diet. Animals ran on a treadmill 4 d · wk at ∼ 70%VO2max for up to 90 min · d for 14 wk. Consistent with the augmentation of skeletal muscle mitochondrial biogenesis and antioxidant defenses, after training there were significant increases in peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) messenger RNA (mRNA) and protein, cytochrome C oxidase subunit IV (COX IV) and cytochrome C protein abundance, citrate synthase activity, Nfe2l2, and SOD2 protein (P < 0.05). Antioxidant supplementation reduced PGC-1α mRNA, PGC-1α and COX IV protein, and citrate synthase enzyme activity (P < 0.05) in both sedentary and exercise-trained rats. Vitamin E and α-lipoic acid supplementation suppresses skeletal muscle mitochondrial biogenesis, regardless of training status.

Dietary β-conglycinin prevents fatty liver induced by a high-fat diet by a decrease in peroxisome proliferator-activated receptor γ2 protein

Diets high in sucrose/fructose or fat can result in hepatic steatosis (fatty liver). Mice fed a high-fat diet, especially that of saturated-fat-rich oil, develop fatty liver with an increase in peroxisome proliferator-activated receptor (PPAR) γ2 protein in liver. The fatty liver induced by a high-fat diet is improved by knockdown of liver PPARγ2. In this study, we investigated whether β-conglycinin (a major protein of soy protein) could reduce PPARγ2 protein and prevent high-fat-diet-induced fatty liver in ddY mice. Mice were fed a high-starch diet (70 energy% [en%] starch) plus 20% (wt/wt) sucrose in their drinking water or a high-safflower-oil diet (60 en%) or a high-butter diet (60 en%) for 11 weeks, by which fatty liver is developed. As a control, mice were fed a high-starch diet with drinking water. Either β-conglycinin or casein (control) was given as dietary protein. β-Conglycinin supplementation completely prevented fatty liver induced by each type of diet, along with a reduction in adipose tissue weight. β-Conglycinin decreased sterol regulatory element-binding protein (SREBP)-1c and carbohydrate response element-binding protein (ChREBP) messenger RNAs (mRNAs) in sucrose-supplemented mice, whereas it decreased PPARγ2 mRNA (and its target genes CD36 and FSP27), but did not decrease SREBP-1c and ChREBP mRNAs, in mice fed a high-fat diet. β-Conglycinin decreased PPARγ2 protein and liver triglyceride (TG) concentration in a dose-dependent manner in mice fed a high-butter diet; a significant decrease in liver TG concentration was observed at a concentration of 15 en%. In conclusion, β-conglycinin effectively prevents fatty liver induced by a high-fat diet through a decrease in liver PPARγ2 protein.

Alterations of Insulin Resistance and the Serum Adiponectin Level in Patients with Type 2 Diabetes Mellitus Under the Usual Antihypertensive Dosage of Telmisartan Treatment

Insulin resistance plays a central role in the pathophysiology of diabetes complications. Angiotensin II receptor blockers (ARBs) regulate angiotensin II receptor-mediated inhibition of intracellular glucose transporter 4 translocation. Telmisartan, one of the known ARBs, was reported to improve insulin resistance via the increase of peroxisome proliferator-activated receptor gamma activity in the model animal. This study examined whether this effect was observed in diabetes patients under the usual antihypertensive dosage of telmisartan treatment. Twenty-seven diabetes patients were chosen for this prospective study. Patient blood pressures were successfully controlled for the most recent 6 months by ARBs other than telmisartan. After informed consent was obtained, we changed to telmisartan from the other ARBs. The parameters of hypertension, hyperlipidemia, glycemic control, and renal function were examined. The values of the homeostasis model assessment of insulin resistance (HOMA-IR) improved from 7.1 +/- 1.5 to 3.8 +/- 3.6 after 3 months. The serum level of adiponectin significantly increased after 6 months. The distributions of other parameters were correlated with that of HOMA-IR or adiponectin. The data indicate that the usual antihypertensive dosage of telmisartan improves insulin resistance and changes adiponectin effect in patients with diabetes mellitus. Adipokine-related insulin resistance and angiotensin II receptor 1-mediated insulin resistance are improved by telmisartan.

Molecular characterization and functional analysis of porcine macrophage migration inhibitory factor (MIF) gene

Originally identified as a cytokine that inhibits the migration of macrophages from capillaries, MIF has now emerged to be a multifunctional factor involved in immune response, glucose and lipid metabolism. We report here the molecular characterization of porcine MIF gene, which resides on chromosome 14q21.3 and encodes 114 amino acids. Porcine MIF mRNA was found to be highly expressed in stomach, to a lesser extent in spleen, and at the lowest levels in skeletal muscle and heart. To gain further insight into the functional regulation of MIF, we cloned the porcine MIF promoter and verified its functionality using luciferase reporter assay. In NIH 3T3 cells, the endogenous MIF mRNA level was up-regulated by rosiglitazone treatment in a dose-dependent manner, which was accompanied by a concurrent increase in peroxisome proliferator-activated receptor (PPAR)gamma2 transcription. Over-expression of porcine PPARgamma2 in NIH 3T3 cells could also up-regulate the transcription of MIF in the absence of rosiglitazone treatment. These observations are consistent with the bioinformatic analysis that reveals two potential PPAR binding sites within the MIF promoter. Additionally, the over-expression of resistin, a factor considered to be a link between inflammation and metabolic signals, could remarkably down-regulate the transcription of MIF in NIH 3T3 cells. Taken together, we proposed that the transcription of MIF is induced by activation of PPARgamma2 and inhibited by excessive resistin.