Acid Oxidation In Mitochondria Research Articles

GLP-1 receptor agonist attenuates tubular cell ferroptosis in diabetes via enhancing AMPK-fatty acid metabolism pathway through macropinocytosis

Kidney tubules are mostly responsible for pathogenesis of diabetic kidney disease. Actively reabsorption of iron, high rate of lipid metabolism and exposure to concentrated redox-active compounds constructed the three main pillars of ferroptosis in tubular cells. However, limited evidence has indicated that ferroptosis is indispensable for diabetic tubular injury. Glucagon-like peptide-1 receptor agonist (GLP-1RA) processed strong benefits on kidney outcomes in people with diabetes. Moreover, GLP-1RA may have additive effects by improving dysmetabolism besides glucose control and weight loss. Therefore, the present study aimed at exploring the benefits of exendin-4, a high affinity GLP-1RA on kidney tubular dysregulation in diabetes and the possible mechanisms involved, with focus on ferroptosis and adenosine 5′-monophosphate-activated protein kinase (AMPK)-mitochondrial lipid metabolism pathway. Our data revealed that exendin-4 treatment markedly improved kidney structure and function by reducing iron overload, oxidative stress, and ACSL4-driven lipid peroxidation taken place in diabetic kidney tubules, along with reduced GPX4 expression and GSH content. AMPK signaling was identified as the downstream target of exendin-4, and enhancement of AMPK triggered the transmit of its downstream signal to activate fatty acid oxidation in mitochondria and suppress lipid synthesis and glycolysis, and ultimately alleviated toxic lipid accumulation and ferroptosis. Further study suggested that exendin-4 was taken up by tubular cells via macropinocytosis. The protective effect of exendin-4 on tubular ferroptosis was abolished by macropinocytosis blockade. Taken together, present work demonstrated the beneficial effects of GLP-1RA treatment on kidney tubular protection in diabetes by suppressing ferroptosis through enhancing AMPK-fatty acid metabolic signaling via macropinocytosis.

Short-chain L-3-hydroxyacyl-CoA dehydrogenase: A novel vital oncogene or tumor suppressor gene in cancers.

The reprogramming of cellular metabolism is frequently linked to tumorigenesis. Glucose, fatty acids, and amino acids are the specific substrates involved in how an organism maintains metabolic equilibrium. The HADH gene codes for the short-chain L-3-hydroxyacyl-CoA dehydrogenase (HADH), a crucial enzyme in fatty acid oxidation that catalyzes the third phase of fatty acid oxidation in mitochondria. Increasing data suggest that HADH is differentially expressed in various types of malignancies and is linked to cancer development and progression. The significance of HADH expression in tumors and its potential mechanisms of action in the onset and progression of certain cancers are summarized in this article. The possible roles of HADH as a target and/or biomarker for the detection and treatment of various malignancies is also described here.

L-Carnitine therapy improves right heart dysfunction throughCpt1-dependent fatty acid oxidation.

Pulmonary arterial hypertension (PAH) is a fatal vasculopathy that ultimately leads to elevated pulmonary pressure and death by right ventricular (RV) failure, which occurs in part due to decreased fatty acid oxidation and cytotoxic lipid accumulation. In this study, we tested the hypothesis that decreased fatty acid oxidation and increased lipid accumulation in the failing RV is driven, in part, by a relative carnitine deficiency. We then tested whether supplementation of l‐carnitine can reverse lipotoxic RV failure through augmentation of fatty acid oxidation. In vivo in transgenic mice harboring a human BMPR2 mutation, l‐carnitine supplementation reversed RV failure by increasing RV cardiac output, improving RV ejection fraction, and decreasing RV lipid accumulation through increased PPARγ expression and augmented fatty acid oxidation of long chain fatty acids. These findings were confirmed in a second model of pulmonary artery banding‐induced RV dysfunction. In vitro, l‐carnitine supplementation selectively increased fatty acid oxidation in mitochondria and decreased lipid accumulation through a Cpt1‐dependent pathway. l‐Carnitine supplementation improves right ventricular contractility in the stressed RV through augmentation of fatty acid oxidation and decreases lipid accumulation. Correction of carnitine deficiency through l‐carnitine supplementation in PAH may reverse RV failure.

A Comprehensive Proteome and Acetyl-Proteome Atlas Reveals Molecular Mechanisms Adapting to the Physiological Changes From Pre-laying to Peak-Laying Stage in Liver of Hens (Gallus gallus).

Along with sexual maturity, the liver undergoes numerous metabolic processes to adapt the physiological changes associated with egg-laying in hens. However, mechanisms regulating the processes were unclear. In this study, comparative hepatic proteome and acetyl-proteome between pre- and peak-laying hens were performed. The results showed that the upregulated proteins were mainly related to lipid and protein biosynthesis, while the downregulated proteins were mainly involved in pyruvate metabolism and were capable of inhibiting gluconeogenesis and lactate synthesis in peak-laying hens compared with that in pre-laying hens. With unchanged expression level, the significant acetylated proteins were largely functioned on activation of polyunsaturated fatty acid oxidation in peroxisome, while the significant deacetylated proteins were principally used to elevate medium and short fatty acid oxidation in mitochondria and oxidative phosphorylation. Most of the proteins which involved in gluconeogenesis, lipid transport, and detoxification were influenced by both protein expression and acetylation. Taken overall, a novel mechanism wherein an alternate source of acetyl coenzyme A was produced by activation of FA oxidation and pyruvate metabolism to meet the increased energy demand and lipid synthesis in liver of laying hens was uncovered. This study provides new insights into molecular mechanism of adaptation to physiological changes in liver of laying hens.

IL-13 Alleviates Cardiomyocyte Apoptosis by Improving Fatty Acid Oxidation in Mitochondria.

Sepsis-induced cardiac injury (SIC) is one of the most common complications in the intensive care unit (ICU) with high morbidity and mortality. Mitochondrial dysfunction is one of the main reasons for SIC, and Interleukin-13 (IL-13) is a master regulator of mitochondria biogenesis. The aim of the present study was to investigate the role of IL-13 in SIC and explore the underlying mechanism. It was found that reactive oxygen species (ROS) production and apoptosis were significantly increased in lipopolysaccharide (LPS)-stimulated primary cardiomyocytes, which was accompanied with obvious mitochondria dysfunction. The results of RNA-sequencing (RNA-seq), mitochondrial membrane potential, fatty acid uptake and oxidation rate suggested that treatment with IL-13 could restore the function and morphology of mitochondria, indicating that it played an important role in protecting septic cardiomyocytes. These findings demonstrated that IL-13 alleviated sepsis-induced cardiac inflammation and apoptosis by improving mitochondrial fatty acid uptake and oxidation, suggesting that IL-13 may prove to be a potential promising target for SIC treatment.

SQLE Mediates Metabolic Reprogramming to Promote LN Metastasis in Castration-Resistant Prostate Cancer.

BackgroundAlmost all metastatic hormone-sensitive prostate cancers (mHSPC) will develop into metastatic castration-resistant prostate cancer (mCRPC) after androgen deprivation therapy (ADT). The expression level of squalene monooxygenase (SQLE) is increased in CRPC cells and regulates cholesterol metabolism. This study verified the biological function and mechanisms of SQLE in CRPC.MethodsThe expression of SQLE in human prostate cancer cells was overexpressed or silenced and its efficacy on cell survival was determined by the MTS test. Energy metabolism phenotype test was evaluated by XF real-time ATP rate assay, XF cell mitochondrial stress test, XF glycolysis stress test and XF mito fuel flex test. Cell migration and invasion were evaluated by colony formation assays and transwell assays; the expression of mRNA and protein was assessed by RT-qPCR and Western blot, respectively. Moreover, BALB/c nude mice model was performed to evaluate the lymph node metastasis.ResultsIn our study, we found that the expression level of SQLE was significantly increased in bicalutamide-resistant-C4-2B cells compared to LNCaP cells. SQLE knockdown partly restored the sensitivity of drug-resistant cells to bicalutamide and reduced lymph node metastasis by inhibiting fatty acid oxidation in mitochondria. We also found that terbinafine, the specific inhibitor of SQLE, can enhance the sensitivity of prostate cancer cells to bicalutamide.ConclusionOur study revealed that SQLE is involved in the progression of castration resistance in CRPC through mediating metabolic reprogramming, presenting SQLE as a new target for the treatment of mCRPC.

The effect of SERCA2 activation on liver metabolism during acute lipotoxicity in vivo

Non‐alcoholic fatty liver disease (NAFLD) is the most common form of liver disease affecting about 30% of the US population. The prognosis for simple liver steatosis is relatively benign; however, chronic inflammation and progressive fibrosis may lead to nonalcoholic steatohepatitis (NASH) and later to cirrhosis and hepatocellular carcinoma. There is currently no established treatment to stop progression from NAFLD to NASH. It was previously shown (Egnatchik RA et al. Mol Metab. 2014; 3 (5): 544–53) that lipotoxic concentrations of fatty acids alter endoplasmic reticulum (ER) calcium stores and induce mitochondrial dysfunction, characterized by elevated citric acid cycle (CAC) flux and reactive oxygen species accumulation, leading to apoptosis. Furthermore, the function of SERCA2 (sarco/endoplasmic reticulum Ca2+‐ATPase), the main protein in hepatocytes that is responsible for transporting Ca2+ from cytoplasm to ER, is impaired in obese mice (Fu S et al. Nature. 2011; 473 (7348): 528–31). We thus hypothesize that restoration of SERCA2 activity might improve mitochondrial function in hepatocytes during acute lipotoxicity.To test this hypothesis, we developed a protocol to investigate the acute impact of fatty acids on liver energy metabolism. Conscious, unrestrained, overnight‐fasted, 12‐week‐old male C57Bl/6J mice were given continuous, intravenous infusions of either saline (control) or 20% lard oil (as described in Stein DT et al. J Clin Invest. 1997; 100 (2): 398–403) for 5 hrs to induce hepatic lipotoxicity. A third group of animals was given lard oil in combination with single intraperitoneal injection of small molecular allosteric activator CDN1163 (50 mg/kg) one week prior to study to activate SERCA2 (Kang S et al. J Biol Chem. 2016; 291 (10): 5185–98). Animals were simultaneously administered a primed, continuous infusion of [6,6‐2H2] glucose and sodium [13C3]lactate intravenously for 4 and 2 hrs, respectively, to assess in vivo liver metabolic fluxes. 13C and 2H‐enrichment of plasma glucose and liver alanine, glutamate, lactate and urea obtained at the end of the study were measured by GC‐MS and used to regress liver metabolic fluxes using a flexible modeling platform (INCA).Our analysis showed that by the end of the experiment both plasma and liver free fatty acids were significantly elevated after lard oil infusion, whereas liver triglycerides and plasma glucose were not affected, regardless of CDN1163 treatment. In contrast, CDN1163 significantly increased alanine aminotransferase and aspartate transaminase content in liver, and restored basal insulin level, which was significantly downregulated in the presence of lard oil alone. Analysis of liver metabolic fluxes revealed that lard oil increased fatty acid oxidation flux. On the other hand, lard oil coupled with CDN1163 led to further upregulation of fatty acid oxidation flux, but at the same time hepatocytes were characterized by increased endogenous glucose production, elevated pyruvate cycling and upregulated CAC activity. These data suggest that SERCA2 activation increases fatty acid oxidation in mitochondria, but at the same time proportionally increases other hepatic fluxes, which might restore energy balance and protect liver during acute lipotoxicity.Support or Funding InformationThis research was supported by NIH grant R01 DK106348.

The Role of Mitochondria in Sex-Dependent Differences in Hepatic Steatosis and Oxidative Stress in Response to Cafeteria Diet-Induced Obesity in Mice.

Female mice fed a cafeteria diet (FCaf) develop higher liver steatosis and oxidative stress than males (MCaf) as a consequence of unresolved ER stress. Here, we investigated whether mitochondria play a role in this sex difference. The isolated mitochondria from FCaf showed more signs of oxidative stress than those of MCaf, correlated with a reduced content of GSH, increased amount of reactive oxygen species (ROS), and lower activities of enzymes involved in ROS neutralisation. Mitochondria from FCaf and MCaf livers exhibited lower rates of succinate-driven state III respiration and reduced ATPase activity in intact coupled mitochondria compared to their controls fed a standard diet (FC and MC), with no differences between the sexes. Fatty acid oxidation in mitochondria and peroxisomes was higher in MCaf and FCaf compared to their respective controls. In the intact perfused liver, there was no difference between sex or diet regarding the fatty acid oxidation rate. These results indicated that cafeteria diet did not affect mitochondrial energy metabolism, even in FCaf livers, which have higher steatosis and cellular oxidative stress. Nevertheless, the increase in mitochondrial ROS generation associated with a decrease in the antioxidant defence capacity, probably contributes to inducing or reinforcing the ER stress in FCaf livers.

Atg7‐Dependent Autophagy Is Essential for Cardiac Function with High Fat Diet.

Heart is a high energy‐demanding tissue. Since 60%–90% energy is from fatty acid oxidation in mitochondria, the regulation of lipid metabolism in the heart is critical. Autophagy, a self‐degradative process, has been reported to be involved in lipid metabolism. Autophagy includes macroautophagy, microautophagy, and chaperone‐mediated autophagy. It has been known that macroautophagy is essential not only for maintaining physiological cardiac function, but also in pathological stressors such as ischemia, and cardiac hypertrophy. However, the molecular pathway through which macroautophagy regulates cardiac lipid metabolism remains unclear. Therefore, it is critical to determine whether macroautophagy is essential in cardiac lipid metabolism.In this study, we evaluated the function of autophagy in cardiac lipid metabolism. First, in order to evaluate the effects of high fat diet (HFD) on cardiac autophagy, cardiac‐specific expression of Tandem fluorescent‐tagged LC3 (mRFP‐EGFP‐LC3)(TF‐LC3) mice were fed either normal diet (ND) or 60% HFD. Through the injection of Chloroquine, an inhibitor of the fusion between autophagosome and lysosome, we evaluated autophagy flux with ND and HFD. In TF‐LC3 mice, autophagic flux was increased with 6 weeks' HFD, but inhibited with 3 months' HFD. Then, we detected mitophagy with HFD. Mitophagy was activated with HFD, as assessed in transgenic mice expressing the mitochondrial‐targeted form of the fluorescent biosensor Keima(Mito‐Keima). Mito‐Keima fluorescence shows pH‐dependent excitation characteristics, shifting excitation maxima to a higher wavelength after mitochondria come into contact with the acidic milieu of lysosomes in the content of mitophagy.Next, to elucidate the role of autophagy in cardiac lipid metabolism, we used genetically altered mouse lines for Atg7, which is responsible for macroautophagy. We generated atg7‐cardiac‐specific knock out (atg7cko) mice. Atg7cko mice were fed HFD for two months. Then through measuring cardiac function by PV‐Loop, atg7cko mice developed severe cardiac systolic (ESPVR=25±2.2 in WT with HF, ESPVR=15±1.3 in atg7cko with HF, p<0.05) and diastolic (EDPVR=0.11±0.02 in WT with HF, EDPVR=0.15±0.01 in atg7cko with HF, p<0.05) dysfunction. Electronic microscope (EM) analysis showed that dysfunctional mitochondria accumulated in atg7cko mice with HFD. Through Tg‐mito‐keima mice crossing with WT or atg7cko mice with ND or HFD, mitophagy was impaired in atg7cko mice with ND and HFD. Mitochondrial membrane potential, mitochondrial oxygen consumption rate (OCR) and fatty acid oxidation (FAO) were decreased in atg7cko mice with HFD. EM analysis and oil red o staining showed lipid droplets were accumulated and Fibrosis and cell death were increased in atg7cko mice during HFD. These results suggested that inhibition of mitophagy and accumulation of dysfunctional mitochondria developed in atg7cko mice with HFD.Taken together, these data indicated that atg7‐dependent autophagy is essential for cardiac function with HFD.Support or Funding InformationNational Institute of Health RO1(1R01HL138720‐01)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Muscle Conditional Medium Reduces Intramuscular Adipocyte Differentiation and Lipid Accumulation through Regulating Insulin Signaling.

Due to the paracrine effects of skeletal muscle, the lipid metabolism of porcine intramuscular (i.m.) preadipocytes was different from that of subcutaneous (s.c.) preadipocytes. To investigate the development of i.m. preadipocytes in vivo, the s.c. preadipocytes were cultured with muscle conditional cultured medium (MCM) for approximating extracellular micro-environment of the i.m. preadipocytes. Insulin signaling plays a fundamental role in porcine adipocyte differentiation. The expression levels of insulin receptor (INSR) and insulin-like growth factor 1 receptor (IGF-1R) in i.m. Preadipocytes were higher than that in s.c. preadipocytes. The effects of MCM on adipocyte differentiation, lipid metabolism and insulin signaling transdution were verified. MCM induced the apoptosis of s.c. preadipocytes but not of s.c. adipocytes. Moreover, MCM inhibited adipocyte differentiation at pre-differentiation and early stages of differentiation, while the expression levels of INSR and IGF-1R were increased. Furthermore, MCM treatment increased adipocyte lipolysis and fatty acid oxidation through induction of genes involved in lipolysis, thermogenesis, and fatty acid oxidation in mitochondria. Consistent with the above, treatment of s.c. adipocytes with MCM upregulated mitochondrial biogenesis. Taken together, MCM can approximate the muscle micro-environment and reduce intramuscular adipocyte differentiation and lipid accumulation via regulating insulin signaling.

Estrogen Signals Through Peroxisome Proliferator-Activated Receptor−γ Coactivator 1α to Reduce Oxidative Damage Associated With Diet-Induced Fatty Liver Disease

Inefficient fatty acid oxidation in mitochondria and increased oxidative damage are features of non-alcoholic fatty liver disease (NAFLD). In rodent models and patients with NAFLD, hepatic expression of peroxisome proliferator-activated receptor-γ (PPARG) coactivator 1α(PPARGC1A or PGC1A) is inversely correlated with liver fat and disease severity. A common polymorphism in this gene (rs8192678, encoding Gly482Ser) has been associated with NAFLD. We investigated whether reduced expression of PGC1A contributes to development of NAFLD using mouse models, primary hepatocytes, and human cell lines. HepG2 cells were transfected with variants of PPARGC1A and protein and messenger RNA levels were measured. Mice with liver-specific hemizygous or homozygous disruption of Ppargc1a (Ppargc1af/+Alb-cre+/0 and Ppargc1af/f Alb-cre+/0 mice, respectively) were fed regular chow (control) or a high-fat diet supplemented with 30% d-fructose in drinking water (obesogenic diet) for 25-33 weeks. Liver tissues were analyzed by histology and by immunoblotting. Primary hepatocytes were analyzed for insulin signaling, reactive oxygen species, and estrogen response. Luciferase reporter expression was measured in transfected H2.35 cells expressing an estrogen receptor reporter gene, estrogen receptor 1, and/or PGC1A/B. The serine 482 variant of the human PGC1A protein had a shorter half-life than the glycine 482 variant when expressed in HepG2 cells. Liver tissues from mice with liver-specific hemizygous disruption of Ppargc1a placed on an obesogenic diet expressed increased markers of inflammation and fibrosis and decreased levels of antioxidant enzymes compared with the Ppargc1a+/+ on the same diet. Oxidative damage was observed in livers from Ppargc1af/+Alb-cre+/0 mice of each sex, in a cell-autonomous manner, but was greater inlivers from the female mice. Expression of PGC1A in H2.35 cells coactivated estrogen receptor 1 and was required for estrogen-dependent expression of genes that encode antioxidant proteins. These findings could account for the increased liver damage observed in female Ppargc1af/+Alb-cre+/0 mice; while, compensatory increases in PPARG coactivator 1β could prevent oxidative damage associated with complete loss of PGC1A expression in Ppargc1af/fAlb-cre+/0 female mice. In mice, loss of estrogen signaling contributes to oxidative damage caused by low levels of PGC1A in liver, exacerbating steatohepatitis associated with diets high in fructose and fat.

Energy metabolic disorder is a major risk factor in severe influenza virus infection: Proposals for new therapeutic options based on animal model experiments.

Severe influenza is characterized by cytokine storm and multiorgan failure. Influenza patients with underlying diseases show a rapid progression in disease severity. The major mechanism that underlies multiorgan failure during the progressive stage of infection, particularly in patients with underlying risk factors, is mitochondrial energy crisis. The relationship between the factors that determine infection severity, such as influenza virus, cytokines, cellular trypsin as a hemagglutinin processing protease for viral multiplication, accumulation of metabolic intermediates and ATP crisis in mitochondria, is termed the "influenza virus-cytokine-trypsin" cycle. This occurs during the initial stages of infection, and is interconnected with the "metabolic disorders-cytokine" cycle in the middle to late phase of infection. Experiments using animal models have highlighted the complex relationship between these two cycles. New treatment options have been proposed that target the ATP crisis and multiorgan failure during the late phase of infection, rather than antiviral treatments with neuraminidase inhibitors that work during the initial phase. These options are (i) restoration of glucose oxidation in mitochondria by diisopropylamine dichloroacetate, which inhibits infection-induced pyruvate dehydrogenase kinase 4 activity, and (ii) restoration of long-chain fatty acid oxidation in mitochondria by l-carnitine and bezafibrate, an agonist of peroxisome proliferation-activated receptors-β/δ, which transcriptionally upregulates carnitine palmitoyltransferase II. The latter is particularly effective in patients with influenza-associated encephalopathy who have thermolabile and short half-life compound variants of carnitine palmitoyltransferase II.

Fatty acid metabolism in pulmonary arterial hypertension: role in right ventricular dysfunction and hypertrophy.

Pulmonary arterial hypertension (PAH) is a complex, multifactorial disease in which an increase in pulmonary vascular resistance leads to increased afterload on the right ventricle (RV), causing right heart failure and death. Our understanding of the pathophysiology of RV dysfunction in PAH is limited but is constantly improving. Increasing evidence suggests that in PAH RV dysfunction is associated with various components of metabolic syndrome, such as insulin resistance, hyperglycemia, and dyslipidemia. The relationship between RV dysfunction and fatty acid/glucose metabolites is multifaceted, and in PAH it is characterized by a shift in utilization of energy sources toward increased glucose utilization and reduced fatty acid consumption. RV dysfunction may be caused by maladaptive fatty acid metabolism resulting from an increase in fatty acid uptake by fatty acid transporter molecule CD36 and an imbalance between glucose and fatty acid oxidation in mitochondria. This leads to lipid accumulation in the form of triglycerides, diacylglycerol, and ceramides in the cytoplasm, hallmarks of lipotoxicity. Current interventions in animal models focus on improving RV dysfunction through altering fatty acid oxidation rates and limiting lipid accumulation, but more specific and effective therapies may be available in the coming years based on current research. In conclusion, a deeper understanding of the complex mechanisms of the metabolic remodeling of the RV will aid in the development of targeted treatments for RV failure in PAH.

Bioactive Natural Matrices and Compounds

The demand for healthy ingredients and a natural way of preventing diseases is contributing to the increased use of natural matrices. There has been a lot of research indicating that general antioxidant properties are not the contributing factors to improving human health but rather the antioxidant properties of specific compounds involved in specific cell signaling mechanisms that need to be elucidated. In this way, beyond the composition of the usual macronutrients and micronutrients, it seems important to also provide information on the composition of natural bioactive compounds. Phytochemicals such as phenolic compounds, essential oils, steroids, vitamins, or pigments should assume high importance due to their documented antioxidant, antimicrobial, antitumour, and anti-inflammatory properties, among others, but the knowledge of the mechanisms of action involved is mandatory. The contributions for this special issue consist of five papers covering several aspects of nutraceuticals and phytochemicals in natural matrices with proven activities in various in vitro or in vivo models. The paper by R. P. Constantin et al. evaluated the effects of three citrus flavanones (hesperidin, hesperetin, and naringenin) on several parameters linked to fatty acid oxidation in mitochondria, peroxisomes, and perfused livers of rats. These results confirm the hypothesis that citrus flavanones are able to induce a more oxidised state in liver cells, altering parameters related to hepatic fatty acid oxidation. The prooxidant effect is most likely a consequence of the ability of these substances to oxidise NADH upon production of phenoxyl radicals in the presence of peroxidases and hydrogen peroxide. A. Chennuru and M. T. S. Saleem described the cardioprotective effects of sesamol against doxorubicin-induced cardiomyopathy in rats. The authors concluded that, sesamol has significant cardioprotection against doxorubicin that induced cardiomyopathy via amelioration of oxidative stress, lipid lowering, and membrane stabilization effect. C. Chaotham et al. evaluated the oral toxicity of a partially purified plaunotol extract (PPE), which is traditionally consumed for its antigastric ulcer properties, using in vivo assays. The acute toxicity study demonstrated that PPE was practically nontoxic based on its high median lethal dose value. The chronic toxicity studies also showed the absence of mortality and clinical symptoms in all treated rats. Therefore, the authors concluded that these results suggest that PPE is potentially safe for further development as a therapeutic agent in humans. In the research study presented by H. A. E. Rabey et al., the protective effect of natural bees' honey on the liver of male albino rats against melamine toxicity was reported. Treating the male albino rats (that were presupplemented regularly with 20000 ppm melamine) with natural bees' honey at a dose of 2.5 g/kg body weight for 28 days improved both liver functions and increased serum protein. In addition, a positive impact on the shape of the cells after treatment with honey, compared to the positive melamine supplemented group, was observed. The authors concluded that the use of natural bees' honey has the ability to protect the livers of rats against the toxic effects of melamine. A. Rasul et al. reviewed recent data on primary flavonoids isolated from plants. Pinocembrin exhibits pharmacological effects on almost all systems, and the authors reviewed its pharmacological and therapeutic applications with specific emphasis on mechanisms of actions. The review suggested that pinocembrin is a potentially promising pharmacological candidate, but additional studies and clinical trials are required to determine the specific intracellular sites of action and derivative targets in order to fully understand the mechanism of its anti-inflammatory, anticancer, and apoptotic effects to further validate pinocembrin medical applications.

Citrus Flavanones Affect Hepatic Fatty Acid Oxidation in Rats by Acting as Prooxidant Agents

Citrus flavonoids have a wide range of biological activities and positive health effects on mammalian cells because of their antioxidant properties. However, they also act as prooxidants and thus may interfere with metabolic pathways. The purpose of this work was to evaluate the effects of three citrus flavanones, hesperidin, hesperetin, and naringenin, on several parameters linked to fatty acid oxidation in mitochondria, peroxisomes, and perfused livers of rats. When exogenous octanoate was used as substrate, hesperetin and naringenin reduced the mitochondrial NADH/NAD+ ratio and stimulated the citric acid cycle without significant changes on oxygen uptake or ketogenesis. When fatty acid oxidation from endogenous sources was evaluated, hesperetin and naringenin strongly reduced the mitochondrial NADH/NAD+ ratio. They also inhibited both oxygen uptake and ketogenesis and stimulated the citric acid cycle. Hesperidin, on the other hand, had little to no effect on these parameters. These results confirm the hypothesis that citrus flavanones are able to induce a more oxidised state in liver cells, altering parameters related to hepatic fatty acid oxidation. The prooxidant effect is most likely a consequence of the ability of these substances to oxidise NADH upon production of phenoxyl radicals in the presence of peroxidases and hydrogen peroxide.

Two ATPases

In this article, I reflect on research on two ATPases. The first is F(1)F(0)-ATPase, also known as ATP synthase. It is the terminal enzyme in oxidative phosphorylation and famous as a nanomotor. Early work on mitochondrial enzyme involved purification in large amount, followed by deduction of subunit composition and stoichiometry and determination of molecular sizes of holoenzyme and individual subunits. Later work on Escherichia coli enzyme utilized mutagenesis and optical probes to reveal the molecular mechanism of ATP hydrolysis and detailed facets of catalysis. The second ATPase is P-glycoprotein, which confers multidrug resistance, notably to anticancer drugs, in mammalian cells. Purification of the protein in large quantity allowed detailed characterization of catalysis, formulation of an alternating sites mechanism, and recently, advances in structural characterization.

Inhibition of myostatin protects against diet-induced obesity by enhancing fatty acid oxidation and promoting a brown adipose phenotype in mice

Although myostatin-null (Mstn (-/-)) mice fail to accumulate fat in adipose tissue when fed a high-fat diet (HFD), little is known about the molecular mechanism(s) behind this phenomenon. We therefore sought to identify the signalling pathways through which myostatin regulates accumulation and/or utilisation of fat. Wild-type, Mstn (-/-) and wild-type mice treated with soluble activin type IIB receptor (sActRIIB) were fed a control chow diet or an HFD for 12 weeks. Changes in gene expression were measured by microarray and quantitative PCR. Histological changes in white adipose tissue were assessed together with peripheral tissue fatty acid oxidation and changes in circulating hormones following HFD feeding. Our results demonstrate that inactivation of myostatin results in reduced fat accumulation in mice on an HFD. Molecular analysis revealed that metabolic benefits, due to lack of myostatin, are mediated through at least two independent mechanisms. First, lack of myostatin increased fatty acid oxidation in peripheral tissues through induction of enzymes involved in lipolysis and in fatty acid oxidation in mitochondria. Second, inactivation of myostatin also enhanced brown adipose formation in white adipose tissue of Mstn (-/-) mice. Consistent with the above, treatment of HFD-fed wild-type mice with the myostatin antagonist, sActRIIB, reduced the obesity phenotype. We conclude that absence of myostatin results in enhanced peripheral tissue fatty acid oxidation and increased thermogenesis, culminating in increased fat utilisation and reduced adipose tissue mass. Taken together, our data suggest that anti-myostatin therapeutics could be beneficial in alleviating obesity.

A case of montelukast-induced churg-strauss syndrome associated with liver dysfunction.

A 64-year-old woman was admitted to hospital due to protracted diarrhea and liver dysfunction. The patient was diagnosed as Churg-Strauss syndrome (CSS) due to asthma, paranasal sinusitis, hypereosinophilia, and polyneuropathy. There was a history of taking montelukast, a leukotriene receptor antagonist (LTRA), which is thought to have some relationship with CSS. The liver biopsy specimen showed eosinophilic infiltration and centrolobular fatty change. In this paper, we review the relationship between LTRA and CSS. Several lines of evidence suggest that leukotriene plays an important role in maintaining neural tissues. We also review the potential relationship between centrolobular fatty change and pivoxil-containing antibiotics, which was prescribed for sinusitis before admission. Carnitine deficiency induced by pivoxil-containing agents may cause impaired fatty acid oxidation in mitochondria.

The Role of Nuclear Receptor NHR-64 in Fat Storage Regulation in Caenorhabditis elegans

Nuclear hormone receptors (NHRs) play vital roles in the regulation of metabolism, reproduction, and development. We found that inactivation of a C. elegans HNF4 homologue nhr-64 by RNA interference (RNAi) suppresses low fat stores in stearoyl-CoA desaturase-deficient fat-6;fat-7 double mutants and sterol regulatory element binding protein (SREBP) sbp-1 mutants. Furthermore, inactivation of nhr-64 improves the growth rate of the fat-6;fat-7and sbp-1 strains. While nhr-64RNAi subtly affects fatty acid composition and fat storage in wild-type C. elegans, its effects on lipid metabolism are most apparent in the background of stearoyl-CoA desaturase or SREBP deficiency. NHR-64 displays transcriptional activating activity when expressed in yeast, and inactivation of nhr-64 affects the expression of at least 14 metabolic genes. Wild-type worms treated with nhr-64 RNAi display increased expression of acetyl-CoA carboxylase as well as increased abundance of de novo synthesized monomethyl branched chain fatty acids, suggesting an increase in fat synthesis. However, reduced expression of the acetyl-CoA synthetase gene acs-2 and an acyl-CoA oxidase gene indicates that a key role of NHR-64 may be to promote fatty acid oxidation in mitochondria and peroxisomes. These studies reveal that NHR-64 is an important regulator of fat storage in C. elegans.

Calcineurin and cardiac function: is more or less better for the heart?

calcineurin (cn) is a Ca2+-calmodulin-activated serine-threonine phosphatase that is ubiquitously expressed and plays an important role in transducing Ca2+-dependent signals. Cn is a heterodimer composed of calmodulin binding catalytic subunit A (CnA) and a Ca2+ binding regulatory subunit B (CnB) ([