Time Course of Decrease in Skeletal Muscle Mitochondrial Biogenesis after Discontinuation of High-Fat Diet.

It is known that a high-fat diet induces an increase in mitochondrial biogenesis in skeletal muscle. To examine the time course of decrease in mitochondrial biogenesis in skeletal muscle after discontinuing a high-fat diet feeding, C57BL/6 mice were fed a high-fat diet for 4 wk and then switched to the control diet for another 3 or 7 d. During the high-fat diet withdrawal period, the protein content of the mitochondrial respiratory chain decreased faster than the fatty acid oxidation enzymes. The mitochondrial DNA copy number remained high for at least 1 wk after withdrawing the high-fat diet. These results suggested that after switching to the control diet following a period of high-fat diet, the increased mitochondrial biogenesis levels are maintained for a few days, and the rate of decline is divergent between the different mitochondrial components.

Fecal fermentation products of common bean-derived fiber inhibit C/EBPα and PPARγ expression and lipid accumulation but stimulate PPARδ and UCP2 expression in the adipogenesis of 3T3-L1 cells.

Clinical and animal studies have suggested efficacies of common bean (Phaseolus vulgaris) consumption on weight loss. Fermentation of common bean-derived dietary fiber by gut microbiota is proposed to mitigate obesity; however, the mechanism of action is unclear. The objective of this study was to investigate whether and how fecal fermentation of common bean-derived dietary fiber impacts adipogenesis in a cell model. Dietary fiber was generated by in vitro digestion of cooked, lyophilized common bean flour, followed by anaerobic fermentation with the use of fresh feces from healthy mice without antibiotics treatment. The murine 3T3-L1 cells were induced to differentiate in the presence of the fermentation products. Treatment of the fecal fermentation products inhibited adipocyte differentiation and lipid accumulation in a dose- and time-dependent manner. The fermentation products decreased (P<.05) protein levels of two key transcription factors for adipogenesis, CCAAT/enhancer binding protein α and peroxisome proliferator-activated receptor γ by 79-92% and 78-90%, respectively, and one of their downstream targets fatty acid binding protein 4 by 49-86% and 63-98% at protein and mRNA levels, respectively, during the time course. In contrast, the fermentation products increased (P<.05) levels of two proteins promoting energy expenditure, peroxisome proliferator-activated receptor δ (71-91%) on days 2 and 4 and mitochondrial uncoupling protein 2 (1.1-1.2 fold) on days 4-8. Altogether, fecal fermentation of dietary fiber derived from in vitro digestion of common bean temporally and dose-dependently inhibits adipogenesis and key adipogenic transactivators, but activates two energy expenditure proteins in 3T3-L1 cells.

Neuro-protective effect of rutin against Cisplatin-induced neurotoxic rat model.

BACKGROUND: Cisplatin is widely used chemotherapeutic agent for cancer treatment with limited uses due to its neurotoxic side effect. The aim of this study was to determine the potential preventive effects of rutin on the brain of cisplatin- neurotoxic rat model. METHODS: Forty rats were divided into four groups. Group-1 (control group) was intra-peritoneal (IP) injected with 2.5 ml/kg saline. Group-2 (rutin group) was orally administrated 30 mg/kg rutin dissolved in water for 14 days. Group-3 (cisplatin group) was IP received 5 mg/kg cisplatin single dose. Group-4 (rutin and cisplatin group) was orally administrated 30 mg/kg rutin dissolved in water for 14 days with a single dose of 5 mg/kg cisplatin IP on day ten. Brain tissues from frontal cortex was used to extract RNA, the gene expression levels of paraoxonase-1 (PON-1), PON-2, PON-3, peroxisome proliferator-activated receptor delta (PPAR-δ), and glutathione peroxidase (GPx) was investigated by Real-time PCR. RESULTS: Cisplatin significantly decreased the expression levels of PON-1, PON-3, PPAR-δ and GPX whereas significantly increased PON-2 expression levels. Co-administration of Rutin prevented the cisplatin-induced toxicity by restoring the alteration in the studied genes to normal values as in the control group. CONCLUSION: This study showed that Rutin has neuroprotective effect and reduces cisplatin- neurotoxicity with possible mechanism via the antioxidant pathway.

Dihydrosterculic acid from cottonseed oil suppresses desaturase activity and improves liver metabolomic profiles of high-fat-fed mice.

Polyunsaturated fatty acid (PUFA)-rich diets are thought to provide beneficial effects toward metabolic health in part through their bioactive properties. We hypothesized that increasing PUFA intake in mice would increase peroxisome proliferator activated receptor delta (PPARδ) expression and activity, and we sought to examine the effect of different PUFA-enriched oils on muscle PPARδ expression. One of the oils we tested was cottonseed oil (CSO) which is primarily linoleic acid (53%) and palmitic acid (24%). Mice fed a CSO-enriched diet (50% energy from fat) displayed no change in muscle PPARδ expression; however, in the liver, it was consistently elevated along with its transcriptional coactivator Pgc-1. Male mice were fed chow or CSO-, saturated fat (SFA)-, or linoleic acid (18:2)-enriched diets that were matched for macronutrient content for 4 weeks. There were no differences in food intake, body weight, fasting glucose, glucose tolerance, or energy expenditure between chow- and CSO-fed mice, whereas SFA-fed mice had increased fat mass and 18:2-fed mice were less glucose tolerant. Metabolomic analyses revealed that the livers of CSO-fed mice closely matched those of chow-fed but significantly differed from SFA- and 18:2-enriched groups. Fatty acid composition of the diets and livers revealed an impairment in desaturase activity and the presence of dihydrosterculic acid (DHSA) in the CSO-fed mice. The effect of DHSA on PPARδ and stearoyl-CoA desaturase-1 expression mimicked that of the CSO-fed mice. Taken together, these data suggest that DHSA from CSO may be an effective means to increase PPARδ expression with concomitant suppression of liver stearoyl-CoA desaturase-1 activity.

PPAR-delta promotes survival of chronic lymphocytic leukemia cells in energetically unfavorable conditions.

Targeting the mechanisms that allow chronic lymphocytic leukemia (CLL) cells to survive in harsh cancer microenvironments should improve patient outcomes. The nuclear receptor peroxisome proliferator activated receptor delta (PPARδ) sustains other cancers, and in silico analysis showed higher PPARD expression in CLL cells than normal lymphocytes and other hematologic cancers. A direct association was found between PPARδ protein levels in CLL cells and clinical score. Transgenic expression of PPARδ increased the growth and survival of CD5+ Daudi cells and primary CLL cells in stressful conditions including exhausted tissue culture media, low extracellular glucose, hypoxia and exposure to cytotoxic drugs. Glucocorticoids and synthetic PPARδ agonists up-regulated PPARD expression and also protected Daudi and primary CLL cells from metabolic stressors. Survival in low glucose was related to increased antioxidant expression, substrate utilization and mitochondrial performance, and was reversed by genetic deletion and synthetic PPARδ antagonists. These findings suggest PPARδ conditions CLL cells to survive in harsh microenvironmental conditions by reducing oxidative stress and increasing metabolic efficiency. Targeting PPARδ may be beneficial in the treatment of CLL.

[Detection of fecal peroxisome proliferator-activated receptor delta and cyclooxygenase 2 mRNA in screening of colorectal cancer].

OBJECTIVE: To evaluate the detection of fecal PPAR-delta and COX-2 mRNA in screening of colorectal cancer. METHODS: Fifty-one patients with colorectal cancer and 21 healthy controls were included in this study. Total RNA was isolated from the fecal samples. Expression of PPAR-delta and COX-2 mRNA was determined by RT-PCR, and its value in screening of colorectal cancer was investigated. RESULTS: The positive detection rate of fecal PPAR-delta and COX-2 mRNA in colorectal cancer patients was significantly higher than that in healthy controls. In 47 colorectal cancer patients and 19 healthy controls with positive fecal ACTB mRNA expression, the sensitivity of fecal PPAR-delta mRNA, COX-2 mRNA and PPAR-delta mRNA plus COX-2 mRNA detection in diagnosing colorectal cancer was 76.6%(36/47), 80.9%(38/47) and 91.5%(43/47) respectively; the specificity was 63.2%(12/19), 84.2%(16/19) and 89.5%(17/19) respectively. CONCLUSION: The combination detection of fecal PPAR-delta and COX-2 mRNA is effective in screening human colorectal cancer and is better than detection of single marker alone.

Antigen recovery and preservation using the microwave irradiation of biological samples for transmission electron microscopy analysis.

Most studies using microwave irradiation (MWI) for the preparation of tissue samples have reported an improvement in structural integrity. However, there have been few studies on the effect of microwave (MW) on antigen preservation during sample preparation prior to immunolocalization. This report documents our experience of specimen preparation using an automatic microwave apparatus to obtain antigen preservation and retrieval. We tested the effects of MW processing vs. conventional procedures on the morphology and antigenicity of two different tissues: the brain and mammary gland, whose chemical composition and anatomical organization are quite different. We chose to locate the transcription factor PPARß/δ using immunocytochemistry on brain tissue sections from hamsters. Antigen retrieval protocols involving MWI were used to restore immunoreactivity. We also studied the efficiency of the ultrastructural immunolocalization of both PPARγ and caveolin-1 following MWI vs. conventional treatment, on mammary gland tissue from mice at 10 days of lactation. Our findings showed that the treatment of tissue samples with MWI, in the context of a process lasting just a few hours from fixation to immunolocalization, enabled similar, or even better, results than conventional protocols. The quantification of immunolabeling for cav-1 indicated an increase in density of up to three-fold in tissues processed in the microwave oven. Furthermore, MW treatment permitted the localization of PPARß/δ in glutaraldehyde-fixed specimens, which was impossible in the absence of MWI. This study thus showed that techniques involving the use of microwaves could largely improve both ultrastructure and immunodetection.

Expression of peroxisome proliferator activator receptor ß/δ (PPARß/δ) in acne vulgaris.

Sebum production is the key factor in the pathophysiology of acne. Studies in sebocyte and human sebaceous gland biology indicate that agonists of peroxisome proliferator-activated receptors (PPARs) alter sebaceous lipid production. Our objective was to detect the expression of PPARß/δ in acne lesions and find its contribution to disease pathogenesis. Twenty five acne vulgaris patients (14 males, 11 females) were included. In addition, 12 healthy volunteers (6 males, 6 females) served as controls. Punch biopsies (3mm) were taken from lesional skin of all patients, non-lesional skin in 12 patients, and from the healthy controls. The biopsies were estimated quantitatively for the level of PPARß/δ mRNA using reverse transcriptase-polymerase chain (RT-PCR) technique. PPARß/δ mRNA levels were significantly higher in patients than controls (p=0.00) and in patients' lesional than non-lesional skin (p=0.00). No significant difference however, was found between inflammatory and non-inflammatory lesions. Age and disease duration had no influence on mean PPAR mRNA levels in lesional skin. PPARß/δ is over expressed-in inflammatory and non-inflammatory acne vulgaris and may well be considered as a candidate target in future acne therapy. However, elucidation of its functional role is recommended.

Carbaprostacyclin, a PPARdelta agonist, ameliorates excess lipid accumulation in diabetic rat placentas.

AIMS: Maternal diabetes impairs placental development and metabolism. Peroxisome proliferator-activated receptors (PPARs) are ligand-activated nuclear receptors relevant in metabolic homeostasis. We investigated the concentrations of PPARdelta and its endogenous agonist prostacyclin (PGI2), as well as the effects of carbaprostacylin (cPGI(2,) a PPARdelta agonist) on lipid metabolism in placentas from control and streptozotocin-induced diabetic rats on day 13.5 of gestation. MAIN METHODS: The placentas were explanted to evaluate PPARdelta expression and PGI2 concentrations, and cultured with cPGI2 for further analysis of lipid metabolism (concentrations and (14)C-acetate derived synthesis of triglycerides, cholesteryl esters, phospholipids, cholesterol and free fatty acids; release of glycerol and lipid peroxidation). KEY FINDINGS: Reduced PGI2 concentrations were found in the placentas from diabetic rats when compared to controls. cPGI2 additions reduced the concentrations and synthesis of several lipid species, increased lipid catabolism and reduced lipid peroxidation in the placenta. These effects were more marked in diabetic tissues, which presented alterations in the lipid metabolic parameters evaluated. cPGI2 additions increased placental PPARdelta and acyl-CoA oxidase expression, which are changes possibly involved in the catabolic effects observed. SIGNIFICANCE: The present study reveals the capability of cPGI2 to regulate placental lipid metabolism and PPARdelta expression, and suggests that preserving appropriate PGI2 concentrations in the placenta may help to metabolize maternal derived lipid overload in diabetic gestations.

Emerging drugs: mechanism of action, mass spectrometry and doping control analysis.

The number of compounds and doping methods in sports is in a state of constant flux. In addition to 'traditional' doping agents, such as anabolic androgenic steroids or erythropoietin, new therapeutics and emerging drugs have considerable potential for misuse in elite sport. Such compounds are commonly based on new chemical structures, and the mechanisms underlying their modes of action represent new therapeutic approaches arising from recent advances in medical research; therefore, sports drug testing procedures need to be continuously modified and complementary methods developed, preferably based on mass spectrometry, to enable comprehensive doping controls. This tutorial not only discusses emerging drugs that can be categorized as anabolic agents (selective androgen receptor modulators, SARMs), gene doping [hypoxia-inducible factor stabilizers, peroxisome-proliferator-activated receptor (PPAR)delta-agonists] and erythropoietin-mimetics (Hematide) but also compounds with potentially performance-enhancing properties that are not classified in the current list of the World Anti-Doping Agency. Compounds such as ryanodine-calstabin-complex modulators (benzothiazepines) are included, their mass spectrometric properties discussed, and current approaches in sports drug testing outlined.

The simultaneous expression of peroxisome proliferator-activated receptor delta and cyclooxygenase-2 may enhance angiogenesis and tumor venous invasion in tissues of colorectal cancers.

We conducted this study to evaluate the impact of the expression of peroxisome proliferator-activated receptor delta on angiogenesis in tissue samples of colorectal cancer. We examined 52 samples of primary human colorectal carcinomas and matched normal adjacent tissues to evaluate the expression of peroxisome proliferator-activated receptor delta, cyclooxygenase-2, vascular endothelial growth factor-A, and CD34 through immunohistochemical analysis. Peroxisome proliferator-activated receptor delta was expressed in 25 (48.1%), and cyclooxygenase-2 was expressed in 26 (50.0%) of total colorectal cancer tissues. Tissue samples were divided into four groups, according to the expression of peroxisome proliferator-activated receptor delta and cyclooxygenase-2. The positive rate of vascular endothelial growth factor-A, the levels of microvascular density, and the incidence of venous vessel invasion in peroxisome proliferator-activated receptor delta (+)/cyclooxygenase-2 (+) samples exceeded significantly those in the other three groups of tissue samples (P<0.05). The results suggest that the axis of the cyclooxygenase-2/peroxisome proliferator-activated receptor delta signal pathway might play a crucial role in the development of colorectal cancers by enhancing angiogenesis.

Quantitative expression patterns of peroxisome proliferator-activated receptor-beta/delta (PPARbeta/delta) protein in mice.

The expression patterns of PPARbeta/delta have been described, but the majority of these data are based on mRNA data. To date, there are no reports that have quantitatively examined the expression of PPARbeta/delta protein in mouse tissues. In the present study, a highly specific PPARbeta/delta antibody was developed, characterized, and used to examine tissue expression patterns of PPARbeta/delta. As compared to commercially available anti-PPARbeta/delta antibodies, one of six polyclonal anti-PPARbeta/delta antibodies developed was significantly more effective for immunoprecipitation of in vitro-translated PPARbeta/delta. This antibody was used for quantitative Western blot analysis using radioactive detection methods. Expression of PPARbeta/delta was highest in colon, small intestine, liver, and keratinocytes as compared to other tissues including heart, spleen, skeletal muscle, lung, brain, and thymus. Interestingly, PPARbeta/delta expression was localized in the nucleus and RXRalpha can be co-immunoprecipitated with nuclear PPARbeta/delta. Results from these studies demonstrate that PPARbeta/delta expression is highest in intestinal epithelium, liver, and keratinocytes, consistent with significant biological roles in these tissues.

PPARdelta enhances keratinocyte proliferation in psoriasis and induces heparin-binding EGF-like growth factor.

Psoriasis is a common skin disease involving keratinocyte proliferation and altered differentiation, as well as T-cell activation. Here, we show that altered gene transcription in psoriatic skin lesions is highly reproducible between independent data sets. Analysis of gene expression confirmed dysregulation in all expected functional categories, such as IFN signaling and keratinocyte differentiation, and allowed molecular fingerprinting of a previously characterized dendritic cell subset associated with psoriasis tumor necrosis factor alpha (TNF-alpha)- and inducible nitric oxide synthase (iNOS)-producing CD11b(INT) DC (Tip-DC). Unexpectedly, a large group of dysregulated transcripts was related to fatty acid signaling and adipocyte differentiation, exhibiting a pattern consistent with the activation of peroxisome proliferator-activated receptor delta (PPARdelta). PPARdelta itself was strongly induced in psoriasis in vivo. In primary keratinocytes, PPARdelta was induced by the transcription factor activator protein 1, in particular by junB, but not by canonical WNT signaling, in contrast to its regulation in colon carcinoma cells. Activation of PPARdelta enhanced proliferation of keratinocytes, while this was inhibited by knockdown of PPARdelta. Finally, heparin-binding EGF-like growth factor (HB-EGF), known to induce epidermal hyperplasia and itself overexpressed in psoriasis, was identified as a direct target gene of PPARdelta. The present data suggest that activation of PPARdelta is a major event in psoriasis, contributing to the hyperproliferative phenotype by induction of HB-EGF.

Activation of PPARdelta inhibits cardiac fibroblast proliferation and the transdifferentiation into myofibroblasts.

OBJECTIVE: The development of heart failure is invariably associated with extensive fibrosis. Treatment with Peroxisome Proliferator-Activated Receptor (PPAR) ligands has been shown to attenuate cardiac fibrosis, but the molecular mechanism underlying this protective effect has remained largely unknown. In this study the potential of each PPAR isoform (PPARalpha, delta, and gamma) to attenuate cardiac fibroblast proliferation, fibroblast (CF) to myofibroblast (CMF) transdifferentiation, and collagen synthesis was investigated. METHODS AND RESULTS: PPARdelta was found to be the most abundant isoform in both CF and CMF. Only the PPARdelta ligand GW501516, but not PPARalpha ligand Wy-14,643 or PPARgamma ligand rosiglitazone, significantly increased PPAR-dependent promoter activity and expression of the PPAR-responsive gene UCP2 ( approximately 5-fold). GW501516 reduced the proliferation rate of CF (-38%) and CMF (-26%), which was associated with increased expression of the cell cycle inhibitor gene G0/G1 switch gene 2 (G0S2). Exposure of CF to the PPARdelta ligand or adenoviral overexpression of PPARdelta significantly decreased alpha-smooth muscle actin (alpha-SMA) levels, indicating a reduced CF to CMF transition. The inhibition of transdifferentiation by PPARdelta correlated with an increase in PTEN (Phosphatase and Tensin Homolog Deleted on Chromosome ten) expression. (3)H-Proline incorporation assays demonstrated a GW501516 induced decline in collagen synthesis (-36%) in CF. CONCLUSION: Cardiac fibroblast proliferation, fibroblast to myofibroblast differentiation and collagen synthesis were reduced after activation of PPARdelta, suggesting that PPARdelta represents an attractive molecular target for attenuating cardiac fibrosis.

Expression profiling of peroxisome proliferator-activated receptor-delta (PPAR-delta) in mouse tissues using tissue microarray.

Peroxisome proliferator-activated receptor-delta (PPAR-delta) is known as a transcription factor involved in the regulation of fatty acid oxidation and mitochondrial biogenesis in several tissues, such as skeletal muscle, liver and adipose tissues. In this study, to elucidate systemic physiological functions of PPAR-delta, we examined the tissue distribution and localization of PPAR-delta in adult mouse tissues using tissue microarray (TMA)-based immunohistochemistry. PPAR-delta positive signals were observed on variety of tissues/cells in multiple systems including cardiovascular, urinary, respiratory, digestive, endocrine, nervous, hematopoietic, immune, musculoskeletal, sensory and reproductive organ systems. In these organs, PPAR-delta immunoreactivity was generally localized on the nucleus, although cytoplasmic localization was observed on several cell types including neurons in the nervous system and cells of the islet of Langerhans. These expression profiling data implicate various physiological roles of PPAR-delta in multiple organ systems. TMA-based immunohistochemistry enables to profile comprehensive protein localization and distribution in a high-throughput manner.

Conjugated linoleic acid reduces phorbol ester-induced prostaglandin F2alpha production by bovine endometrial cells.

Recent interest in conjugated linoleic acid (CLA) research stems from the well-documented anticarcinogenic, antiatherogenic, antidiabetic, and antiobesity properties of CLA in animal models. The objective of this study was to examine the effects of 2 CLA isomers (cis-9,trans-11 and trans-10,cis-12) on phorbol 12,13-dibutyrate (PDBu)-induced PGF2alpha production in cultured bovine endometrial (BEND) cells. Confluent BEND cells were incubated in the absence (control) or presence of 100 microM each of linoleic acid, cis-9,trans-11 CLA, or trans-10,cis-12 CLA for 24 h. After incubation, cells were rinsed and then stimulated with PDBu (100 ng/mL) for 6 h. Compared with untreated cells, PDBu stimulated PGF2alpha secretion (+25-fold) within 6 h. The increases in PGF(2alpha) secretion were paralleled by signifi-cant induction of prostaglandin endoperoxide synthase-2 (PGHS-2) mRNA (+63-fold) and protein (+1.6-fold) expression. In spite of stimulatory effects on PGHS-2 and peroxisome proliferator-activated receptor delta (PPARdelta) mRNA responses, CLA greatly decreased PGF2alpha production by PDBu-stimulated BEND cells. There was no evidence for PDBu or CLA modulation of PPARdelta protein synthesis in cultured BEND cells. Results indicated that CLA modulation of PGF2alpha production by BEND cells was not mediated through PGHS-2 or PPARdelta gene repression.

Modulation of peroxisome proliferator-activated receptor delta and gamma 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.

Quantitative analysis of PPARdelta mRNA by real-time RT-PCR in 86 rectal cancer tissues.

AIM: The purpose of this study is to clarify the expression change of PPARdelta gene in human colorectal cancer tissues. METHODS: Applying real-time RT-PCR, we quantified PPARdelta mRNA in a series of 86 tissues from excised primary rectal cancers. In each case, accompanying normal mucosa was collected for comparison. RESULTS: Among the 86 rectal cancer tissues, 48 cases showed PPARdelta overexpression: 39 tumours gave an expression level 1.5-5 times, five tumours 10-20 times, and four tumours more than 20 times relative to normal mucosa. However, the general level of PPARdelta mRNA in rectal cancer tissues is not statistically different from normal mucosa. CONCLUSIONS: The expression of PPARdelta gene in rectal cancers is not statistically different from normal mucosa.