Induction Of Fatty Acid Oxidation Research Articles

Quercetin restores respiratory mucosal barrier dysfunction in Mycoplasma gallisepticum-infected chicks by enhancing Th2 immune response.

Mycoplasma gallisepticum (MG) has long been a pathogenic microorganism threatening the global poultry industry. Previous studies have demonstrated that the mechanism by which quercetin (QUE) inhibits the colonization of MG in chicks differs from that of antibiotics. However, the molecular mechanism by which QUE facilitates the clearance of MG remains unclear. The aim of this study was to investigate the molecular mechanism of MG clearance by QUE, with the expectation of providing new options for the treatment of MG. A model of MG infection in chicks and MG-induced M1 polarization in HD-11 cells were established. The mechanism of QUE clearance of MG was investigated by evaluating the relationship between tracheal mucosal barrier integrity, antibody levels, Th1/Th2 immune balance and macrophage metabolism and M1/M2 polarization balance. Furthermore, network pharmacology and molecular docking techniques were employed to explore the potential molecular pathways connecting QUE, M2 polarization, and fatty acid oxidation (FAO). The findings indicate that QUE remodels tracheal mucosal barrier function by regulating tight junctions and secretory immunoglobulin A (sIgA) expression levels. This process entails the regulatory function of QUE on the Th1/Th2 immune imbalance that is induced by MG infection in the tracheal mucosa. Moreover, QUE intervention impeded the M1 polarization of HD-11 cells induced by MG infection, while simultaneously promoting M2 polarization through the induction of FAO. Conversely, inhibitors of the FAO pathway impede this effect. The results of computer network analysis suggest that QUE may induce FAO via the PI3K/AKT pathway to promote M2 polarization. Notably, inhibition of the PI3K/AKT pathway was found to effectively inhibit M2 polarization in HD-11 cells, while having a limited effect on FAO. QUE promotes M2 polarization of HD-11 cells to enhance Th2 immune response through FAO and PI3K/AKT pathways, thereby restoring tracheal mucosal barrier function and ultimately inhibiting MG colonization.

Induction of Fatty Acid Oxidation Underlies DNA Damage-Induced Cell Death and Ameliorates Obesity-Driven Chemoresistance.

The DNA damage response is essential for preserving genome integrity and eliminating damaged cells. Although cellular metabolism plays a central role in cell fate decision between proliferation, survival, or death, the metabolic response to DNA damage remains largely obscure. Here, this work shows that DNA damage induces fatty acid oxidation (FAO), which is required for DNA damage-induced cell death. Mechanistically, FAO induction increases cellular acetyl-CoA levels and promotes N-alpha-acetylation of caspase-2, leading to cell death. Whereas chemotherapy increases FAO related genes through peroxisome proliferator-activated receptor α (PPARα), accelerated hypoxia-inducible factor-1α stabilization by tumor cells in obese mice impedes the upregulation of FAO, which contributes to its chemoresistance. Finally, this work finds that improving FAO by PPARα activation ameliorates obesity-driven chemoresistance and enhances the outcomes of chemotherapy in obese mice. These findings reveal the shift toward FAO induction is an important metabolic response to DNA damage and may provide effective therapeutic strategies for cancer patients with obesity.

GC‑MSC‑derived circ_0024107 promotes gastric cancer cell lymphatic metastasis via fatty acid oxidation metabolic reprogramming mediated by the miR‑5572/6855‑5p/CPT1A axis.

Gastric cancer tissue‑derived mesenchymal stem cells (GC‑MSCs) play a critical role in facilitating gastric cancer metastasis. Recently, circular RNAs (circRNAs) and metabolic reprogramming have been found to be extensively involved in the malignant progression of tumors, including gastric cancer. However, the biological role and potential mechanisms of GC‑MSC‑derived circRNAs in metabolic reprogramming remain elusive. Herein, the expression profiles of circRNAs and mRNAs were compared between GC‑MSCs and bone marrow‑derived MSCs (BM‑MSCs) using microarray analysis. circ_0024107 was identified to mediate GC‑MSCs to promote gastric cancer lymphatic metastasis by inducing fatty acid oxidation (FAO) metabolic reprogramming. Mechanistically, circ_0024107 served as a sponge of miR‑5572 and miR‑6855‑5p to elicit the FAO metabolic reprograming of GC‑MSCs by upregulating carnitine palmitoyltransferase 1A (CPT1A). In addition, GC‑MSCs promoted metastasis which was dependent on the induction of FAO in gastric cancer cells mediated by circ_0024107. The circ_0024107/miR‑5572/6855‑5p/CPT1A axis was deregulated in gastric cancer tissues and GC‑MSCs, and was associated with lymph node metastasis and the prognosis of patients with gastric cancer. Taken together, the findings of the present study suggest the crucial role of FAO metabolic reprogramming mediated by GC‑MSC‑derived circ_0024107 in synergistically promoting gastric cancer lymphatic metastasis via miR‑5572/6855‑5p‑CPT1A signaling; this suggests that circ_0024107 may be an attractive target for gastric cancer intervention.

OPA1 Regulates Lipid Metabolism and Cold-Induced Browning of White Adipose Tissue in Mice.

Mitochondria play a vital role in white adipose tissue (WAT) homeostasis including adipogenesis, fatty acid synthesis, and lipolysis. We recently reported that the mitochondrial fusion protein optic atrophy 1 (OPA1) is required for induction of fatty acid oxidation and thermogenic activation in brown adipocytes. In the current study we investigated the role of OPA1 in WAT function in vivo. We generated mice with constitutive or inducible knockout of OPA1 selectively in adipocytes. Studies were conducted under baseline conditions, at thermoneutrality, following high-fat feeding or during cold exposure. OPA1 deficiency reduced mitochondrial respiratory capacity in white adipocytes, impaired lipolytic signaling, repressed expression of de novo lipogenesis and triglyceride synthesis pathways, and promoted adipose tissue senescence and inflammation. Reduced WAT mass was associated with hepatic triglycerides accumulation and glucose intolerance. Moreover, mice deficient for OPA1 in adipocytes had impaired adaptive thermogenesis and reduced cold-induced browning of subcutaneous WAT and were completely resistant to diet-induced obesity. In conclusion, OPA1 expression and function in adipocytes are essential for adipose tissue expansion, lipid biosynthesis, and fatty acid mobilization of WAT and brown adipocytes and for thermogenic activation of brown and beige adipocytes.

Role of Perivascular Adipose Tissue-Derived Adiponectin in Vascular Homeostasis

Studies of adipose tissue biology have demonstrated that adipose tissue should be considered as both passive, energy-storing tissue and an endocrine organ because of the secretion of adipose-specific factors, called adipokines. Adiponectin is a well-described homeostatic adipokine with metabolic properties. It regulates whole-body energy status through the induction of fatty acid oxidation and glucose uptake. Adiponectin also has anti-inflammatory and antidiabetic properties, making it an interesting subject of biomedical studies. Perivascular adipose tissue (PVAT) is a fat depot that is conterminous to the vascular wall and acts on it in a paracrine manner through adipokine secretion. PVAT-derived adiponectin can act on the vascular wall through endothelial cells and vascular smooth muscle cells. The present review describes adiponectin’s structure, receptors, and main signaling pathways. We further discuss recent studies of the extent and nature of crosstalk between PVAT-derived adiponectin and endothelial cells, vascular smooth muscle cells, and atherosclerotic plaques. Furthermore, we argue whether adiponectin and its receptors may be considered putative therapeutic targets.

S100A4 enhances protumor macrophage polarization by control of PPAR-γ-dependent induction of fatty acid oxidation

BackgroundThe peroxisome proliferator-activated receptor γ (PPAR-γ)-dependent upregulation of fatty acid oxidation (FAO) mediates protumor (also known as M2-like) polarization of tumor-associated macrophages (TAMs). However, upstream factors determining PPAR-γ upregulation in...

Comparative Analysis of the Effects of Long-Term 3,5-diiodothyronine Treatment on the Murine Hepatic Proteome and Transcriptome Under Conditions of Normal Diet and High-Fat Diet.

Background: The thyroid hormone (TH) metabolite 3,5-diiodothyronine (3,5-T2) is considered as a potential drug for treatment of nonalcoholic fatty liver disease (NAFLD) based on its prominent antisteatotic effects in murine models of obesity without the detrimental thyromimetic side effects known for classical TH. To expand our understanding of its mode of action, we comprehensively characterized the effects of 3,5-T2 on hepatic gene expression in a diet-induced murine model of obesity by a combined liver proteome and transcriptome analysis. Materials and Methods: Male C57BL/6 mice fed high-fat diet (HFD) to induce NAFLD or standard diet (SD) as control were treated with 2.5 μg/g body weight 3,5-T2 or saline for 4 weeks. We performed mass spectrometry analyses and integrated those proteome data with earlier published microarray-based transcriptome data from the same animals. In addition, concentrations of several sex steroids in serum and different tissues were determined by gas chromatography-tandem mass spectrometry. Results: We observed limited concordance between transcripts and proteins exhibiting differential abundance under 3,5-T2 treatment, which was only partially explainable by methodological reasons and might, therefore, reflect noncanonical post-transcriptional events. The treatment affected the levels of more and partially different proteins under HFD as compared with SD, demonstrating response modulation by the hepatic lipid load. The hepatic physiological signatures of 3,5-T2 treatment inferable from the omics data comprised the reduction of oxidative stress and alteration of apolipoprotein profiles, both due to decreased liver fat content. In addition, induction of several classical TH target genes and genes involved in the biosynthesis of cholesterol, bile acids (BAs), and male sex steroids was observed. The latter finding was supported by hepatic sex steroid measurements. Conclusion: While confirming the beneficial hepatic liver fat reduction by 3,5-T2 treatment, our data suggest that besides the well-known induction of fatty acid oxidation the stimulation of cholesterol- and BA synthesis with subsequent excretion of the latter through bile might represent a further important mechanism in this context. The obvious intensified male sex steroid exposition of the liver in 3,5-T2-treated HFD animals can be predicted to cause enhanced hepatic "masculinization," with not yet clear but potentially detrimental physiological consequences.

MON-672 Progesterone Receptor Membrane Component 1 Suppresses Lipid Accumulation and Lipotoxicity in Animal Model of Diabetic Cardiomyopathy (DCM)

Diabetic cardiomyopathy (DCM) is one of the complications triggered by type II diabetes (T2D) (1). When free fatty acids (FFA) are abundant in insulin resistant pre-diabetic patients because of adipose lipolysis, FFA tends to move toward heart (2). Lipid accumulation can cause cardiac lipotoxicity and exacerbate DCM (3). In previous study, Pgrmc1 has been identified to associate with fatty acid synthesis (4). Therefore, we assumed that Pgrmc1 will associate with DCM. By feeding high-fat diet for 8 weeks and injecting streptozotocin (30mg/kg), T2D and DCM were induced. The lipid accumulation was exacerbated in T2D-induced Pgrmc1 KO heart, and FFA level was also high. Levels of lipid metabolic genes showed the tendency for lipid accumulation and lipotoxicity, and glycolysis was induced in T2D-induced Pgrmc1 KO heart. Though glycolysis presents higher efficiency for energy production in cardiomyopathy (5), it did not compensate the impairment of mitochondrial respiration in Pgrmc1 KO heart. High-fat diet and streptozotocin could not be the interfering factors, because suppression of fatty acid oxidation, induction of glycolysis, and impairment of mitochondrial respiration were observed similarly in post-prandial mice which were fed with normal chow. Insulin was excluded for interfering factor as cell line with serum starvation showed mitochondrial suppression and glycolytic induction in flux analyzer analysis in Pgrmc1 knockdown. Conversely, induction of fatty acid oxidation and suppression of glycolysis were observed in 72 h fasting of Pgrmc1 KO heart, suggesting the nutrition is closely associated with the metabolic modulation of Pgrmc1 on heart. This metabolic phenotype of Pgrmc1 KO heart consequently exacerbated DCM by showing high levels of fibrosis, inflammation, endoplasmic reticulum stress, and oxidative stress.

Strategies for Measuring Induction of Fatty Acid Oxidation in Intestinal Stem and Progenitor Cells.

This protocol describes a multipronged approach that we have created to determine the transcriptional induction of fatty acid oxidation (FAO) genes in Lgr5high intestinal stem cells and a subsequent metabolomics-based approach for assessing fatty acid utilization in the mammalian intestinal crypt. More specifically, we describe methods for crypt isolation followed by a FACS-based purification of stem and progenitor populations and RNA-sequencing analysis. Using this workflow, we can determine both basal gene expression profiles of key metabolic genes as well as corresponding changes in response to altered metabolic states, such as fasting. Subsequently, we describe a complementary metabolomics-based approach that we have developed to assess fatty acid uptake and utilization in the crypt using 13C stable isotope tracing. Combining these approaches, one can gain a better understanding of substrate utilization and the preceding transcriptional changes that accommodate these reactions in physiologic states of low carbohydrate utilization or during overabundance of dietary lipids.

Mulberry ethanol extract attenuates hepatic steatosis and insulin resistance in high-fat diet–fed mice

Nonalcoholic fatty liver disease is one of the most common complications of obesity. Mulberry is an important source of phytochemicals, such as anthocyanins, polyphenols and flavonoids, which are related to its antioxidant activity. In this study, we developed a hypothesis that mulberry exerted beneficial effects on metabolic disorders and evaluated the influence of the mulberry ethanol extract (MEE) on high-fat diet–induced hepatic steatosis and insulin resistance in mice. Thirty-six male C57BL/6J mice were assigned into 3 groups and fed either a low-fat diet or a high-fat diet with or without supplementation with MEE. Our results showed that administration of MEE reduced diet-induced body weight gain, improved high-fat diet–induced hepatic steatosis and adipose hypertrophy, alleviated insulin resistance, and improved glucose homeostasis. Analysis of hepatic gene expression indicated that MEE treatment changed the expression profile of genes involved in lipid and cholesterol metabolism. In conclusion, the present study demonstrated that MEE supplementation protected mice from high-fat diet–induced obesity, hepatic steatosis, and insulin resistance. Moreover, the protective effects of MEE were associated with the induction of fatty acid oxidation and decreased fatty acid and cholesterol biosynthesis.

Notch1 deficiency decreases hepatic lipid accumulation by induction of fatty acid oxidation.

Notch signaling pathways modulate various cellular processes, including cell proliferation, differentiation, adhesion, and communication. Recent studies have demonstrated that Notch1 signaling also regulates hepatic glucose production and lipid synthesis. However, the effect of Notch1 signaling on hepatic lipid oxidation has not yet been directly investigated. To define the function of Notch1 signaling in hepatic lipid metabolism, wild type mice and Notch1 deficient antisense transgenic (NAS) mice were fed a high-fat diet. High-fat diet -fed NAS mice exhibited a marked reduction in hepatic triacylglycerol accumulation compared with wild type obese mice. The improved fatty liver was associated with an increased expression of hepatic genes involved in fatty acid oxidation. However, lipogenic genes were not differentially expressed in the NAS liver, suggesting lipolytic-specific regulatory effects by Notch1 signaling. Expression of fatty acid oxidative genes and the rate of fatty acid oxidation were also increased by inhibition of Notch1 signaling in HepG2 cells. In addition, similar regulatory effects on lipid accumulation were observed in adipocytes. Taken together, these data show that inhibition of Notch1 signaling can regulate the expression of fatty acid oxidation genes and may provide therapeutic strategies in obesity-induced hepatic steatosis.

SG-04 * THE eEF2 KINASE, A MEDIATOR OF MEDULLOBLASTOMA ADAPTATION TO METABOLIC STRESS, SUPPORTS FATTY ACID OXIDATION

During tumour progression, brain tumour cells are exposed to nutrient deprivation due to defective tumour vasculature. The ability of brain tumour cells to adapt to reduced nutrient availability favours selection for aggressive clones. The molecular pathways supporting such metabolic adaptation are still poorly defined. We previously reported that the translation elongation factor 2 kinase (eEF2K), which controls mRNA translation at the step of elongation, is an evolutionarily conserved mediator of the response to nutrient deprivation. Gene expression analysis show that eEF2K expression is upregulated in the most aggressive subgroup of medulloblastoma (MB), namely group 3, and that high eEF2K expression is strongly associated with poor survival in both MB. In addition, genetic targeting of eEF2K significantly increases sensitivity of MB cells to nutrient deprivation, supporting a role for eEF2K in facilitating adaptation of MB to nutrient stress. To decipher the basis for eEF2K protective functions under nutrient deprivation, we performed gene expression analysis of eEF2K proficient versus deficient cells under nutrient-deprived conditions. Gene set enrichment analysis (GSEA) highlighted fatty acid oxidation (FAO) as one of the biological pathways most dramatically deregulated upon eEF2K loss. Remarkably, many genes involved in FAO are downregulated in eEF2K deficient cells under starvation, including genes encoding acyl-coA synthetases and acyl-coA dehydrogenases. Furthermore, cells lacking eEF2K are deficient in metabolizing exogenous palmitate to produce ATP, strongly supporting a role for eEF2K in stimulating FAO activity. Finally, our data show that pharmacological induction of FAO in eEF2K deficient cells using bezafibrate was sufficient to rescue cell death occurring under nutrient depleted conditions. The molecular basis for eEF2K-mediated regulation of the FAO transcriptional program is under investigation. Together, our work supports a critical role for eEF2K in driving FAO activity under nutrient deprivation, which could profoundly impact medulloblastoma adaptation to nutrient stress and therefore emergence of aggressive phenotypes.

Transplacental induction of fatty acid oxidation in term fetal pigs by the peroxisome proliferator-activated receptor alpha agonist clofibrate.

BackgroundTo induce peroxisomal proliferator-activated receptor α (PPARα) expression and increase milk fat utilization in pigs at birth, the effect of maternal feeding of the PPARα agonist, clofibrate (2-(4-chlorophenoxy)-2-methyl-propanoic acid, ethyl ester), on fatty acid oxidation was examined at full-term delivery (0 h) and 24 h after delivery in this study. Each group of pigs (n = 10) was delivered from pregnant sows fed a commercial diet with or without 0.8% clofibrate for the last 7 d of gestation. Blood samples were collected from the utero-ovarian artery of the sows and the umbilical cords of the pigs as they were removed from the sows by C-section on day 113 of gestation.ResultsHPLC analysis identified that clofibric acid was present in the plasma of the clofibrate-fed sow (~4.2 μg/mL) and its offspring (~1.5 μg/mL). Furthermore, the maternal-fed clofibrate had no impact on the liver weight of the pigs at 0 h and 24 h, but hepatic fatty acid oxidation examined in fresh homogenates showed that clofibrate increased (P < 0.01) 14C-accumulation in CO2 and acid soluble products 2.9-fold from [1-14C]-oleic acid and 1.6-fold from [1-14C]-lignoceric acid respectively. Correspondingly, clofibrate increased fetal hepatic carnitine palmitoyltransferase (CPT) and acyl-CoA oxidase (ACO) activities by 36% and 42% over controls (P < 0.036). The mRNA abundance of CPT I was 20-fold higher in pigs exposed to clofibrate (P < 0.0001) but no differences were detected for ACO and PPARα mRNA between the two groups.ConclusionThese data demonstrate that dietary clofibrate is absorbed by the sow, crosses the placental membrane, and enters fetal circulation to induce hepatic fatty acid oxidation by increasing the CPT and ACO activities of the newborn.

Flavangenol (pine bark extract) and its major component procyanidin B1 enhance fatty acid oxidation in fat-loaded models

Flavangenol, one of several pine bark extract products, is expected to prevent metabolic diseases with its potent antioxidant effect, its anti-obesity effect and its improvement of insulin sensitivity. In this study, targeting the liver as one of the organs that plays an important role in energy metabolism, Flavangenol was investigated for its effect on non-alcoholic fatty liver disease (NAFLD), its action mechanism and its active ingredients, using in vivo and in vitro experiment systems. Flavangenol suppressed intrahepatic fat accumulation in Western diet-loaded Tsumura Suzuki Obese Diabetes (TSOD) mice, which develop various metabolic diseases. In addition, Flavangenol significantly increased the mRNA expression levels of fatty acid oxidative enzymes (peroxisomal proliferator-activated receptor α, acyl-CoA oxidase, carnitine palmitoyltransferase). In order to investigate the direct effect of Flavangenol on the liver, an in vitro fatty liver model prepared by adding a free fatty acid to human liver cancer cells (HepG2 cells) was used. In this model, Flavangenol significantly suppressed intracellular fat accumulation. Procyanidin B1, one of the major components of Flavangenol, also suppressed fat accumulation and induced mRNA expression of the fatty acid oxidative enzymes. As mentioned above, Flavangenol showed a significant suppressive effect in the NAFLD model, and it was suggested that the molecular mechanism is induction of fatty acid oxidation, with the effect mainly attributed to procyanidin B1.

Induction of fatty acid oxidation resists weight gain, ameliorates hepatic steatosis and reduces cardiometabolic risk factors

Fatty acid oxidation has been implicated in amelioration of obesity by burning off excessive accumulated lipid. BPR697, a peripheral cannabinoid receptor 1 (CB1) antagonist, elevated fat oxidation without added energy expenditure. Its impact on food intake, body weight changes and metabolic alterations were examined in rats fed standard chow and in diet-induced obesity (DIO) mice. CB1 agonist-induced hypothermia and analgesia responses were measured to examine the brain activity of BPR697. The acute effects of BPR697 on food intake, body weight change and post-absorptive metabolic profiles were investigated in rats. Energy utilization with BPR697 was examined by indirect calorimetry. Chronic treatment of DIO mice was used to evaluate the long-term effects of BPR697. Distribution of BPR697 was significantly biased in favor of the periphery instead of the brain, as shown by its low brain/plasma concentration ratio and confirmed by the negative response of BPR697 in CB1 agonist-induced hypothermia and analgesia. When administered to rats at 20 mg kg(-1), BPR697 showed a unique spectrum of effects with significant weight loss without altered food intake. Furthermore, BPR697 increased serum levels of free fatty acids and ketone bodies and reduced hepatic lipid accumulation with preservation of liver glycogen in postprandial rats. Indirect calorimetric profiling of BPR697 revealed a similar trend, shifting whole-body energy catabolism toward fat oxidation, but without elevated energy expenditure. In DIO mice with chronic treatment, animals treated with BPR697 at 20 mg kg(-1) resisted weight gain and showed a reduction of high-fat-induced cardiometabolic abnormalities such as hyperglycemia, abdominal fat and liver steatosis. The induction of fatty acid oxidation without concomitant elevation of energy expenditure by the peripheral CB1 antagonist BPR697 is sufficient to cause substantial weight loss in chow-fed rats. In the presence of high-dietary fat intake, BPR697 resists weight gain and alleviates obesity-related cardiometabolic risk factors.

Ameliorative Effects of Mulberry (Morus albaL.) Leaves on Hyperlipidemia in Rats Fed a High-Fat Diet: Induction of Fatty Acid Oxidation, Inhibition of Lipogenesis, and Suppression of Oxidative Stress

To determine the effects of mulberry (Morus alba L.) leaves on hyperlipidemia, we performed gene expression profiling of the liver. Rats were fed a high-fat diet and administered mulberry leaves for 7 weeks. Plasma triglyceride and non-esterified fatty acid levels were significantly lower in the rats treated with mulberry leaves as compared with the untreated rats. DNA microarray analysis revealed that mulberry leaves upregulated expression of the genes involved in α-, β- and ω-oxidation of fatty acids, mainly related to the peroxisome proliferator-activated receptor signaling pathway, and downregulated the genes involved in lipogenesis. Furthermore, treatment with mulberry leaves upregulated expression of the genes involved in the response to oxidative stress. These results indicate that consumption of fatty acids and inhibition of lipogenesis are responsible for the reduction in plasma lipids caused by mulberry administration. In addition, mulberry treatment maintains the body's oxidative state at a low level despite enhancing fatty acid oxidation.

PPARδ Agonism Activates Fatty Acid Oxidation via PGC-1α but Does Not Increase Mitochondrial Gene Expression and Function

PPARδ (peroxisome proliferator-activated receptor δ) is a regulator of lipid metabolism and has been shown to induce fatty acid oxidation (FAO). PPARδ transgenic and knock-out mice indicate an involvement of PPARδ in regulating mitochondrial biogenesis and oxidative capacity; however, the precise mechanisms by which PPARδ regulates these pathways in skeletal muscle remain unclear. In this study, we determined the effect of selective PPARδ agonism with the synthetic ligand, GW501516, on FAO and mitochondrial gene expression in vitro and in vivo. Our results show that activation of PPARδ by GW501516 led to a robust increase in mRNA levels of key lipid metabolism genes. Mitochondrial gene expression and function were not induced under the same conditions. Additionally, the activation of Pdk4 transcription by PPARδ was coactivated by PGC-1α. PGC-1α, but not PGC-1β, was essential for full activation of Cpt-1b and Pdk4 gene expression via PPARδ agonism. Furthermore, the induction of FAO by PPARδ agonism was completely abolished in the absence of both PGC-1α and PGC-1β. Conversely, PGC-1α-driven FAO was independent of PPARδ. Neither GW501516 treatment nor knockdown of PPARδ affects PGC-1α-induced mitochondrial gene expression in primary myotubes. These results demonstrate that pharmacological activation of PPARδ induces FAO via PGC-1α. However, PPARδ agonism does not induce mitochondrial gene expression and function. PGC-1α-induced FAO and mitochondrial biogenesis appear to be independent of PPARδ.

Lipotoxicity: Why do saturated fatty acids cause and monounsaturates protect against it?

Lipotoxicity: Why do saturated fatty acids cause and monounsaturates protect against it?

Effect of (+)-usnic acid on mitochondrial functions as measured by mitochondria-specific oligonucleotide microarray in liver of B6C3F 1 mice

Usnic acid is a lichen metabolite used as a weight-loss dietary supplement due to its uncoupling action on mitochondria. However, its use has been associated with severe liver disorders in some individuals. Animal studies conducted thus far evaluated the effects of usnic acid on mitochondria primarily by measuring the rate of oxygen consumption and/or ATP generation. To obtain further insight into usnic acid-mediated effects on mitochondria, we examined the expression levels of 542 genes associated with mitochondrial structure and functions in liver of B6C3F 1 female mice using a mitochondria-specific microarray. Beginning at 8 weeks of age, mice received usnic acid at 0, 60, 180, and 600 ppm in ground, irradiated 5LG6 diet for 14 days. Microarray analysis showed a significant effect of usnic acid on the expression of several genes only at the highest dose of 600 ppm. A prominent finding of the study was a significant induction of genes associated with complexes I through IV of the electron transport chain. Moreover, several genes involved in fatty acid oxidation, the Krebs cycle, apoptosis, and membrane transporters were over-expressed. Usnic acid is a lipophilic weak acid that can diffuse through mitochondrial membranes and cause a proton leak (uncoupling). The up-regulation of complexes I–IV may be a compensatory mechanism to maintain the proton gradient across the mitochondrial inner membrane. In addition, induction of fatty acid oxidation and the Krebs cycle may be an adaptive response to uncoupling of mitochondria.

Anti-Obesity Effect of Fish Oil and Fish Oil-Fenofibrate Combination in Female KK Mice

The aim of our study is to elucidate the effects of EPA- or DHA-rich fish oil, and of the latter plus fenofibrate, on lipid metabolism in female KK mice. Female KK mice were fed purified experimental diets containing lard/safflower oil (4:6, Lard/SO), EPA-rich fish oil (EPA), DHA-rich fish oil (DHA), or DHA-rich fish oil plus 0.2% (w/w) fenofibrate (DHA+FF) for 8 weeks. At the end of the experiments, we measured levels of plasma lipids, hepatic triglycerides, and cholesterol, as well as the hepatic mRNA expression of lipogenic and lipidolytic genes. The final body weight of EPA- and DHA-fed groups was significantly lower than that of the Lard/SO-fed group, and that of the DHA+FF-fed group was the lowest. All three fish oil treatments significantly reduced plasma insulin levels. Hepatic lipid levels significantly decreased in all three of these groups compared with the Lard/SO-fed group. Plasma adiponectin increased in both the EPA-and DHA-fed groups, but the increase was suppressed in the DHA+FF-fed group. Hepatocytes of Lard/SO-fed mice were filled with numerous fat droplets, but fat accumulation was inhibited in both EPA- and DHA-fed mice and was significantly prevented by fenofibrate treatment. SREBP-1c mRNA levels were decreased by about half in EPA- and DHA-fed mice compared with Lard/SO-fed mice. FAS, Insig-1, HMG-CoA reductase, and LDL-receptor mRNA levels also markedly decreased in both EPA- and DHA-fed mice, but there was no additional decrease in DHA+FF fed mice. Fenofibrate treatment significantly induced mRNA expression of AOX and UCP-2, but not of PPARalpha. These data suggest that fish oil inhibited body weight gain and exhibited an anti-obesity effect through the inhibition of lipid synthesis in female KK mice. Furthermore, fenofibrate treatment markedly inhibited body weight gain by the induction of fatty acid oxidation. Plasma adiponectin levels did not increase in mice fed DHA-rich fish oil with fenofibrate, although white adipose tissue (WAT) weight significantly decreased. We considered that adiponectin sensitivity increased more in mice fed DHA-rich fish oil with fenofibrate than in mice fed DHA-rich fish oil alone.