Peroxisome Proliferator-activated Receptor Gamma Coactivator-1α Research Articles

Effect of quercetin on nonshivering thermogenesis of brown adipose tissue in high-fat diet-induced obese mice

Activating nonshivering thermogenesis in brown adipose tissue (BAT) is a promising strategy to prevent obesity. This study investigated whether quercetin supplementation improves obesity in mice by increasing nonshivering thermogenesis in BAT and white adipose tissue (WAT) browning. Compared to high-fat diet (HFD)-fed mice, mice fed a HFD supplemented with 1% quercetin (HFDQ) had reduced body weight and total plasma cholesterol. In HFDQ-fed mice, retroperitoneal WAT (RWAT) weight was decreased, and browning effect and lipolysis were increased. HFDQ-fed mice had increased expression of nonshivering thermogenesis genes in BAT, including uncoupling protein 1 (UCP1), peroxisome proliferator-activated receptor-gamma coactivator 1α (PGC1α), cell death-inducing DFFA-like effector A (CIDEA), and mitochondrial transcriptional factor A (mtTFA). Quercetin supplementation increased genes and proteins in β3-adrenergic receptor (ADRB3), p38 mitogen-activated protein kinase (MAPK), and AMP-activated protein kinase (AMPK) pathways in HFD-fed mice, which were suppressed by an AMPK inhibitor or an ADRB3 antagonist. Energy expenditure and core body temperature were not changed by quercetin, but physical activity was increased in HFDQ mice during dark periods at room and cold temperatures. Quercetin also decreased the Firmicutes to Bacteroidetes ratio and increased short-chain fatty acid production in the feces of HFD-fed mice. In summary, quercetin supplementation in HFD-fed mice may attenuate obesity. Although the study did not show consistency in data at molecular and pathophysiological levels between BAT function and obesity, it also shows promising health effects of quercetin, accompanied by improved physical activity and gut microbiota dysbiosis.

Metformin protects high glucose‑cultured cardiomyocytes from oxidative stress by promoting NDUFA13 expression and mitochondrial biogenesis via the AMPK signaling pathway.

Tissue damage in diabetes is at least partly due to elevated reactive oxygen species production by the mitochondrial respiratory chain during hyperglycemia. Sustained hyperglycemia results in mitochondrial dysfunction and the abnormal expression of mitochondrial genes, such as NADH: Ubiquinone oxidoreductase subunit A13 (NDUFA13). Metformin, an AMP-activated protein kinase (AMPK) activator, protects cardiomyocytes from oxidative stress by improving mitochondrial function; however, the exact underlying mechanisms are not completely understood. The aim of the present study was to investigated the molecular changes and related regulatory mechanisms in the response of H9C2 cardiomyocytes to metformin under high glucose conditions. H9C2 cells were subjected to CCK-8 assay to assess cell viability. Reactive oxygen species generation was measured with DCFH-DA assay. Western blotting was used to analyze the expression levels of NDUFA13, AMPK, p-AMPK and GAPDH. Reverse transcription-quantitative PCR was used to evaluate the expression levels of mitochondrial genes and transcription factors. It was observed that metformin protected H9C2 cardiomyocytes by suppressing high glucose (HG)-induced elevated oxidative stress. In addition, metformin stimulated mitochondrial biogenesis, as indicated by increased expression levels of mitochondrial genes (NDUFA1, NDUFA2, NDUFA13 and manganese superoxide dismutase) and mitochondrial biogenesis-related transcription factors [peroxisome proliferator-activated receptor-gamma coactivator-1α, nuclear respiratory factor (NRF)-1, and NRF-2] in the metformin + HG group compared with the HG group. Moreover, metformin promoted mitochondrial NDUFA13 protein expression via the AMPK signaling pathway, which was abolished by pretreatment with the AMPK inhibitor, Compound C. The results suggested that metformin protected cardiomyocytes against HG-induced oxidative stress via a mechanism involving AMPK, NDUFA13 and mitochondrial biogenesis.

Effect of Ubiquinol on Glaucomatous Neurodegeneration and Oxidative Stress: Studies for Retinal Ganglion Cell Survival and/or Visual Function.

Oxidative stress is one of major causal factors in glaucomatous neurodegeneration. Ubiquinol promotes retinal ganglion cell (RGC) survival against glaucomatous insults such as oxidative stress. Here we investigated the effect of ubiquinol on RGC survival and/or visual function in mouse models of glaucoma and oxidative stress. DBA/2J and age-matched DBA/2J-Gpnmb+ (D2-Gpnmb+), which do not develop intraocular pressure elevation, or C57BL/6J mice were fed with ubiquinol (1%) or control diet daily for 5 or 2 months. We assessed RGC survival by Brn3a immunohistochemistry and measured expression levels of active and total BAX, peroxisome proliferator-activated receptor-gamma coactivator 1α, transcription factor A (TFAM) and oxidative phosphorylation (OXPHOS) complex protein. Following induction of oxidative stress by paraquat injection, we also assessed visual function. In glaucomatous retina, ubiquinol supplementation significantly promoted RGC survival, blocked BAX activation and increased TFAM and OXPHOS complex II protein expression. Also, ubiquinol supplementation ameliorated oxidative stress-induced visual dysfunction. These findings indicate that ubiquinol promotes RGC survival by increasing TFAM expression and OXPHOS complex II activity in glaucomatous neurodegeneration, and that ubiquinol enhances RGC survival and preserves visual function against oxidative stress. We propose that ubiquinol has a therapeutic potential for treating oxidative stress-associated glaucomatous neurodegeneration.

Docosahexaenoic and eicosapentaenoic fatty acids differentially regulate glucose and fatty acid metabolism in L6 rat skeletal muscle cells.

The objective of this study was to investigate whether the n-3 polyunsaturated fatty acids (PUFAs) docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) can directly regulate glucose and fat metabolism in skeletal muscle besides exerting anti-inflammatory effects. To accomplish this, L6 skeletal muscle cells were treated with 50 µM of either DHA or EPA for 1, 3, and 5 days. Here, we report that basal and insulin-stimulated rates of glucose uptake, glycogen synthesis, protein kinase B (AKT), and glycogen synthase kinase 3 (GSK3) phosphorylation were not affected by DHA or EPA. However, glucose and palmitate oxidation were consistently elevated by DHA treatment, whereas EPA only increased this variable transiently. Similarly, only DHA caused significant and sustained increases in AMP-activated protein kinase (AMPK) phosphorylation and protein levels of carnitine-palmitoyl transferase-1b (CPT1b) and peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) in skeletal muscle cells. DHA also caused a larger anti-inflammatory effect than EPA in these cells. In conclusion, besides exerting anti-inflammatory effects, DHA and EPA directly regulated glucose and fat metabolism in skeletal muscle cells, although DHA was more effective in doing so than EPA. Thus, by directly enhancing glucose and fat oxidation, DHA may increase glucose disposal and reduce intramyocellular lipid accumulation.

Increased energy expenditure and activated β3-AR-cAMP-PKA signaling pathway in the interscapular brown adipose tissue of 6-OHDA-induced Parkinson's disease model rats.

To explore the possible mechanism of weight loss in Parkinson's disease (PD). Bilateral injections of 6-hydroxydopamine (6-OHDA) into substantia nigra (SN) were performed to induce the PD model rats. The rotarod test, food intake, body weight, and interscapular brown adipose tissue (IBAT) weight were recorded 6 weeks postoperation. HE staining was performed to observe the morphology of multilocular adipose cells in IBAT. Immunohistochemistry and western blot were used to determine the protein levels of tyrosine hydroxylase (TH) in the SN, and the levels of uncoupling protein 1 (UCP1), peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α), phosphorylated-hormone sensitive lipase (p-HSL), HSL, TH, β3-adrenergic receptor (β3-AR), cyclic adenosine monophosphate (cAMP), and protein kinase A (PKA) in IBAT. After treatment with 6-OHDA for 6 weeks, 6-OHDA rats exhibited decreased TH expression in SN accompanied with shortened staying time on the rotating rod. This motor impairment paralleled with no significant alteration in body mass, IBAT weight, and food intake until the end of the experimental protocol. However, the decreasing diameter of the single fat vesicle in IBAT was observed in the 6-OHDA group. Meanwhile, compared with the control group, the protein expression of UCP1, PGC-1α, p-HSL, TH, β3-AR, cAMP, and PKA in IBAT were increased significantly in the 6-OHDA group, whereas no obvious change in the expression of HSL. The present study suggested an increased energy expenditure and activation of the β3-AR-cAMP-PKA signaling pathway in the IBAT after the destruction of the dopamine system in the SN of the rat.

Association of PPARG and PPARGC1 polymorphism with effectiveness of exercise-induced fat mass loss

Aim. Peroxisome proliferator activated receptor gamma (PPARG) and PPARG coactivator 1α (PPARGC1A) is a key regulator of energy metabolism. This study examines the influence of PPARG and PPARGC1A gene polymorphisms on the PPARG expression, obesity risk, lipoprotein profile and effectiveness of the physical activity intervention for improvement of these parameters. Methods. 39 women with BMI>30 kg/m2 participated in the three-months fitness-program and followed a hypocaloric diet (1500 kCal). At the beginning and at the end of the program, the following anthropometric and biochemical parameters were measured: BMI, percentage of total and visceral fat, amount of plasma lipoproteins, cholesterol, and triglycerides. Single nucleotide polymorphisms were identified in PPARG (n=94) and PPARGC1A (n=138) genes. PPARG mRNA expression was measured through reverse transcription PCR. Results. The physical exercise intervention resulted in a significant fat mass loss in all participants (40.3±5.3% before the study vs 36.4±5.7% after the study, P<0.00001). Polymorphisms rs6442311, rs6846769, rs6846769 were associated with lower visceral fat percent, rs6442311 also correlated with PPARG expression. PPARGC1A polymorphisms rs4458444, rs2305681 were associated with plasma lipoproteins, cholesterol, and triglyceride content. Weight loss effectiveness was connected with rs17650401, rs9833097, rs12629751. Conclusions. After correction for multiple comparisons only rs17650401, of PPARGC1A gene was associated with more effective fat mass reduction.
 Keywords: PPARG, obesity, single nucleotide polymorphism, weight loss, exercise intervention.

Waterborne copper exposure up-regulated lipid deposition through the methylation of GRP78 and PGC1α of grass carp Ctenopharyngodon idella

Early molecular events after the exposure of heavy metals, such as aberrant DNA methylation, suggest that DNA methylation was important in regulating physiological processes for animals and accordingly could be used as environmental biomarkers. In the present study, we found that copper (Cu) exposure increased lipid content and induced the DNA hypermethylation at the whole genome level. Especially, Cu induced hypermethylation of glucose-regulated protein 78 (grp78) and peroxisome proliferator-activated receptor gamma coactivator-1α (pgc1α). CCAAT/enhancer binding protein α (C/EBPα) could bind to the methylated sequence of grp78, whereas C/EBPβ could not bind to the methylated sequence of grp78. These synergistically influenced grp78 expression and increased lipogenesis. In contrast, DNA methylation of PGC1α blocked the specific protein 1 (SP1) binding and interfered mitochondrial function. Moreover, Cu increased reactive oxygen species (ROS) production, activated endoplasmic reticulum (ER) stress and damaged mitochondrial function, and accordingly increased lipid deposition. Notably, we found a new toxicological mechanism for Cu-induced lipid deposition at DNA methylation level. The measurement of DNA methylation facilitated the use of these epigenetic biomarkers for the evaluation of environmental risk.

SIRT1 Activation by Polydatin Alleviates Oxidative Damage and Elevates Mitochondrial Biogenesis in Experimental Diabetic Neuropathy.

Mitochondrial dysfunction has been implicated as a one of the major factors linked to the development of painful diabetic neuropathy (DN). Several studies have demonstrated that sirtuin (SIRT1) activation recuperates nerve function by activating mitochondrial biogenesis. Polydatin, a resveratrol glycoside, has been explored to improve mitochondrial function via SIRT1 activation. However, the neuroprotective effects of polydatin in DN remain elusive. In this study, polydatin (25 and 50mg/kg, oral) was administered for last 2weeks of 8-week study to diabetic Sprague-Dawley rats weighing 250-300g (post 6-weeks of streptozotocin 55mg/kg, intraperitoneal). Treatment with polydatin significantly attenuated mechanical and thermal hyperalgesia in diabetic rats. Treated diabetic rats also showed improvement in motor/sensory nerve conduction velocities and nerve blood flow. For in vitro studies, Neuro2a cells were exposed to high-glucose (30mM) condition to simulate short-term hyperglycemia. Polydatin was evaluated for its role in SIRT1 and Nrf2 activation at a dose of 5, 10, and 20µM concentrations. Polydatin exposure normalized the mitochondrial superoxides, membrane potentials and improved neurite outgrowth in high-glucose-exposed Neuro2a cells. Increased SIRT1 activation by polydatin resulted in peroxisome proliferator activated receptor-gamma coactivator-1α (PGC-1α) directed mitochondrial biogenesis. SIRT1 activation also facilitated Nrf2-directed antioxidant signaling. Study results inferred that decline in mitochondrial biogenesis and oxidative function in diabetic rats and high-glucose-exposed Neuro2a cells, could be counteracted by polydatin administration, postulated via enhancing SIRT1 and Nrf2 axis.

Transcriptional Dysregulation in Huntington's Disease: The Role in Pathogenesis and Potency for Pharmacological Targeting.

Huntington's disease (HD) is an inherited neurodegenerative disorder caused by a mutation in the gene that encodes a critical cell regulatory protein, huntingtin (Htt). The expansion of cytosine-adenine-guanine (CAG) trinucleotide repeats causes improper folding of functional proteins and is an initial trigger of pathological changes in the brain. Recent research has indicated that the functional dysregulation of many transcription factors underlies the neurodegenerative processes that accompany HD. These disturbances are caused not only by the loss of wild-type Htt (WT Htt) function but also by the occurrence of abnormalities that result from the action of mutant Htt (mHtt). In this review, we aim to describe the role of transcription factors that are currently thought to be strongly associated with HD pathogenesis, namely, RE1-silencing transcription factor, also known as neuron-restrictive silencer factor (REST/NRSF), forkhead box proteins (FOXPs), peroxisome proliferator-activated receptor gamma coactivator-1a (PGC1α), heat shock transcription factor 1 (HSF1), and nuclear factor κ light-chain-enhancer of activated B cells (NF- κB). We also take into account the role of these factors in the phenotype of HD as well as potential pharmacological interventions targeting the analyzed proteins. Furthermore, we considered whether molecular manipulation resulting in changes in transcription factor function may have clinical potency for treating HD.

PGC-1α differentially regulates the mRNA expression profiles of genes related to myofiber type specificity in chicken

Previous studies on mammals showed that peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) played a prominent role in regulating muscle fiber type transition and composition. However, the role of PGC-1α in chicken muscle has seldom been explored. To investigate the effect of PGC-1α on chicken skeletal muscles in this study, the PGC-1α gene was overexpressed or silenced in chicken primary myoblasts by using lentivirus, and then the effects of the PGC-1α gene overexpression and knockdown on the mRNA expression profile of genes related to myofiber type specificity were examined during fiber formation. The results showed that overexpression of PGC-1α from proliferation to differentiation was accompanied by the up-regulated expression of Pax7, MyoD, and CnAα, which was significantly (P<0.01) increased after one day of transfection (1I). The enhancement of MyoG, MEF2c, and MyHC SM expression lagged, which was improved significantly (P<0.01) after four days of transfection (1I3D). Overexpression of PGC-1α decreased (P<0.01) the MyHC FWM expression after four days of transfection (1I3D), and it had no significant impact (P>0.05) on the expression of CnB1, NFATc3, and MyHC FRM during myofiber formation. The effective silence (P<0.01) of PGC-1α by lentivirus mediating short hairpin RNA (shRNA) was detected after four days of transfection (1I3D) in cultures, and the lack of its function in chicken primary myoblasts significantly (P<0.01) down-regulated the expression of Pax7, MyoD, CnAα, MyoG, MEF2c, and MyHC SM, significantly (P<0.01) up-regulated the expression of MyHC FWM, and had no significant impact (P>0.05) on the expression of CnB1, NFATc3, and MyHC FRM. These results indicated that the role of PGC-1α in regulating the fiber type specificity of chicken skeletal muscles might be similar to that in mammals, which interplayed with key genes related to myocyte differentiation and calcineurin signaling pathway.

PGC-1α regulates autophagy to promote fibroblast activation and tissue fibrosis

ObjectivesCoactivators are a heterogeneous family of transcriptional regulators that are essential for modulation of transcriptional outcomes and fine-tune numerous cellular processes. The aim of the present study was to evaluate...

Mitochondria Biogenesis Modulates Iron-Sulfur Cluster Synthesis to Increase Cellular Iron Uptake.

Iron-sulfur (Fe-S) clusters are required for mitochondrial function. Fe-S cluster synthesis occurs in the mitochondria and iron uptake is required for mitochondrial biogenesis. However, Fe-S clusters inhibit the expression of the iron importer transferrin receptor 1 (TfR1), whereas lack of the Fe-S cluster stimulates TfR1 expression. Yet, it is unclear whether Fe-S cluster synthesis increases with mitochondria biogenesis and, in turn, whether this negatively modulates TfR1 expression. We manipulated peroxisome proliferator-activated receptor-gamma coactivator-1α expression to control mitochondrial biogenesis in a variety of cell types, including erythroid cells. We demonstrated that Fe-S cluster synthesis increases with mitochondria biogenesis but does not interfere with increasing TfR1 expression. In fact, TfR1 expression is stimulated through alternative means to meet iron requirement for mitochondria biogenesis. Furthermore, under enhanced mitochondria biogenesis, increased Fe-S cluster synthesis inhibits the function of iron-regulating protein (IRP)1 and hence stimulates the expression of 5'-aminolevulinate synthase 2 (ALAS2), a target of IRP1 and rate-limiting enzyme in erythroid heme biogenesis. Increased ALAS2 expression leads to enhanced heme production, hemoglobinization, and erythropoiesis. Therefore, our study also provides a mechanism to link mitochondrial biogenesis with erythropoiesis and has a potential therapeutic value in the treatment of blood disorders.

The Peroxisome Proliferator-Activated Receptor-Gamma Coactivator-1α-Heme Oxygenase 1 Axis, a Powerful Antioxidative Pathway with Potential to Attenuate Diabetic Cardiomyopathy.

Significance: From studies of diabetic animal models, the downregulation of peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α)-heme oxygenase 1 (HO-1) axis appears to be a crucial event in the development of obesity and diabetic cardiomyopathy (DCM). In this review, we discuss the role of metabolic and biochemical stressors in the rodent and human pathophysiology of DCM. A crucial contributor for many cardiac pathologies is excessive production of reactive oxygen species (ROS) pathologies, which lead to extensive cellular damage by impairing mitochondrial function and directly oxidizing DNA, proteins, and lipid membranes. We discuss the role of ROS production and inflammatory pathways with multiple contributing and confounding factors leading to DCM. Recent Advances: The relevant biochemical pathways that are critical to a therapeutic approach to treat DCM, specifically caloric restriction and its relation to the PGC-1α-HO-1 axis in the attenuation of DCM, are elucidated. Critical Issues: The increased prevalence of diabetes mellitus type 2, a major contributor to unique cardiomyopathy characterized by cardiomyocyte hypertrophy with no effective clinical treatment. This review highlights the role of mitochondrial dysfunction in the development of DCM and potential oxidative targets to attenuate oxidative stress and attenuate DCM. Future Directions: Targeting the PGC-1α-HO-1 axis is a promising approach to ameliorate DCM through improvement in mitochondrial function and antioxidant defenses. A pharmacological inducer to activate PGC-1α and HO-1 described in this review may be a promising therapeutic approach in the clinical setting.

Resveratrol protects mitochondrial quantity by activating SIRT1/PGC-1α expression during ovarian hypoxia.

PurposeResveratrol is a well‐known potent activator of sirtuin‐1 (SIRT1). We investigated the direct effects of hypoxia and resveratrol on SIRT1/ peroxisome proliferator‐activated receptor‐gamma coactivator 1α (PGC‐1α) pathways, vascular endothelial growth factor (VEGF), hypoxia‐inducible factor (HIF)‐1α, and mitochondrial quantity in a steroidogenic human ovarian granulosa‐like tumor cell line (KGN) cells.MethodsKGN cells were cultured with cobalt chloride (CoCl2; a hypoxia‐mimicking agent) and/or resveratrol. The mRNA and protein levels, protein secretion, and intracellular localization were assessed by real‐time PCR, Western blot analysis, ELISA, and immunofluorescence staining, respectively. Mitochondrial quantity was measured based on the mitochondrial DNA (mtDNA) copy number.ResultsCoCl2 simultaneously attenuated the levels of SIRT1 and mtDNA expression, and induced the levels of VEGF protein production. In contrast, resveratrol significantly increased the levels of SIRT1 and mtDNA copy number, but reduced VEGF production in normoxia. Resveratrol could recover CoCl2‐suppressed SIRT1 and mtDNA expression and antagonize CoCl2‐induced VEGF production. CoCl2 treatment resulted in a downregulation of PGC‐1α expression, and this effect was recovered by resveratrol. Resveratrol significantly suppressed the production of the CoCl2‐induced HIF‐1α and VEGF proteins.ConclusionThese results suggest that resveratrol improves mitochondrial quantity by activating the SIRT1/PGC‐1α pathway and inhibits VEGF induction through HIF‐1α under hypoxic conditions.

Effect of Quercetin Treatment on Mitochondrial Biogenesis and Exercise-Induced AMP-Activated Protein Kinase Activation in Rat Skeletal Muscle

The purpose of this study was to evaluate the effect of chronic quercetin treatment on mitochondrial biogenesis, endurance exercise performance and activation levels of AMP-activated protein kinase (AMPK) in rat skeletal muscle. Rats were assigned to a control or quercetin group and were fed for 7 days. Rats treated with quercetin showed no changes in the protein levels of citrate synthase or cytochrome C oxidase IV or those of sirtuin 1, peroxisome proliferator-activated receptor gamma coactivator-1α or phosphorylated AMPK. After endurance swimming exercise, quercetin-treated rats demonstrated no differences in blood and muscle lactate levels or glycogen utilization speed compared to control rats. These results indicate that quercetin treatment does not stimulate mitochondrial biogenesis in skeletal muscle and does not influence metabolism in a way that might enhance endurance exercise capacity. On the other hand, the AMPK phosphorylation level immediately after exercise was significantly lower in quercetin-treated muscles, suggesting that quercetin treatment might provide a disadvantage to muscle adaptation when administered with exercise training. The molecular results of this study indicate that quercetin treatment may not be advantageous for improving endurance exercise performance, at least after high-dose and short-term therapy.

Hypermethylation of the Gene Coding for PGC-1α in Peripheral Blood Leukocytes of Patients With Parkinson's Disease.

Decreased expression of peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) is implicated in the pathophysiology of Parkinson’s disease (PD). However, our understanding of the mechanism regulating the PGC-1α expression is still limited. We sought to determine whether the epigenetic modification of PPARGC1A (the gene encoding PGC-1α) could account for its diminished expression. We performed a study of PPARGC1A risk-SNP genotypes, methylation level, and the expression in blood from 171 subjects. The mean DNA methylation level of PPARGC1A intron 1 in patients with PD was higher than that in the controls (7.18 ± 1.74 vs. 6.36 ± 1.28, P = 0.007). A detailed comparison of the DNA methylation level at each CpG site showed that CpG_1, CpG_13.14, CpG_17.18, and CpG_20 were significantly hypermethylated in patients with PD. There was a significant negative correlation between PPARGC1A methylation and expression level (R = −0.404, P < 0.001). We found no correlations between the PPARGC1A methylation level and the clinical features, while the CpG_13.14 site methylation level was positively correlated with H&Y stage (R = 0.246, P = 0.020) and was increased in people carrying the rs2970848 AA genotype compared with that in carriers of the AG/GG genotype (7.27 ± 1.86 vs. 6.65 ± 1.92, P = 0.032). Our results support a link between PPARGC1A methylation, gene expression, and variability, which indicated that a novel epigenetic regulatory mechanism controlling PPARGC1A expression influences PD pathogenesis.

Melatonin elicits protective effects on OGD/R‑insulted H9c2 cells by activating PGC‑1α/Nrf2 signaling.

Melatonin (Mel) elicits beneficial effects on myocardial ischemia/reperfusion injury. However, the underlying mechanism of Mel against oxygen-glucose deprivation/ reperfusion (OGD/R)-induced H9c2 cardiomyocyte damage remains largely unknown. The aim of the present study was to investigate the biological roles and the potential mechanisms of Mel in OGD/R-exposed H9c2 cardiomyocytes. The results of the present study demonstrated that Mel significantly elevated the viability and reduced the activity of lactate dehydrogenase and creatine kinase myocardial band in a doseand time-dependent manner in OGD/R-insulted H9c2 cells. In addition, Mel suppressed OGD/R-induced oxidative stress in H9c2 cells, as demonstrated by the decreased reactive oxygen species and malondialdehyde levels, as well as the increased activities of superoxide dismutase, catalase and glutathione peroxidase. Mel exerted an antioxidant effect by activating the peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α)/nuclear factor erythroid 2-related factor 2 (Nrf2) signaling. Mel reduced the expression of OGD/R-enhanced pro-inflammatory tumor necrosis factor-α (TNF-α), interleukin (IL)-6, IL-1β, IL-8 and monocyte chemotactic protein-1. Mel also abolished the OGD/R-induced increase in H9c2 apoptosis, as evidenced by mitochondrial membrane potential restoration and caspase-3 and caspase-9 inactivation, as well as the upregulation of Bcl-2 and down-regulation of cleaved caspase-3 and Bax. The Mel-induced antiapoptotic effects were dependent on PGC-1α/TNF-α signaling. Overall, the results of the present study demonstrated that Mel alleviated OGD/R-induced H9c2 cell injury via the inhibition of oxidative stress and inflammation by regulating the PGC-1α/Nrf2 and PGC-1α/TNF-α signaling pathways, suggesting a promising role for Mel in the treatment of ischemic heart disease.

Protective Effects of Hydrogen on Myocardial Mitochondrial Functions in Septic Mice.

Enhancement of mitochondrial physiological function prevents sepsis-induced dysfunction. The present study aimed to elucidate the mechanism by which hydrogen (H2) affects mitochondrial function in a wild-type (WT) and homozygous nuclear factor erythroid 2-related factor 2 (Nrf2) knockout (KO, Nrf2−/−) murine model of sepsis. In myocardial tissues with severe sepsis, H2 gas treatment reduced mitochondrial dysfunction, whereas zinc protoporphyrin (ZnPPIX) negated these beneficial effects. H2 treatment upregulated the protein expression of mitofusin-2 (Mfn2), peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α), and protein heme oxygenase-1 (HO-1) in WT mice with severe sepsis but not in their Nrf2−/− counterparts, and this upregulation was inhibited in the presence of ZnPPIX. In conclusion, the mechanism by which H2 limits organ damage in mice with severe sepsis involves HO-1, whereas the mechanism that limits severe sepsis-related mitochondrial dysfunction involves both HO-1 and Nrf2.

LB100 ameliorates nonalcoholic fatty liver disease via the AMPK/Sirt1 pathway.

BACKGROUNDIt is well known that nonalcoholic fatty liver disease (NAFLD) is associated with insulin resistance (IR). LB100, a serine/threonine protein phosphatase 2A (PP2A) inhibitor, is closely related to IR. However, there is little data regarding its direct influence on NAFLD.AIMTo elucidate the effect and underlying mechanism of LB100 in NAFLD.METHODSAfter 10 wk of high fat diet (HFD) feeding, male C57BL/6 mice were injected intraperitoneally with vehicle or LB100 for an additional 6 wk (three times a week). The L02 cell line was treated with LB100 and free fatty acids (FFAs) for 24 h. Hematoxylin and eosin and oil red O staining were performed for histological examination. Western blot analysis was used to detect the protein expression of Sirtuin 1 (Sirt1), total and phosphorylated AMP-activated protein kinase α (AMPKα), and the proteins involved in lipogenesis and fatty acid oxidation. The mRNA levels were determined by qPCR. Pharmacological inhibition of AMPK was performed to further examine the exact mechanism of LB100 in NAFLD.RESULTSLB100 significantly ameliorated HFD-induced obesity, hepatic lipid accumulation and hepatic injury in mice. In addition, LB100 significantly downregulated the protein levels of acetyl-CoA carboxylase, sterol regulatory element-binding protein 1 and its lipogenesis target genes, including stearoyl-CoA desaturase-1 and fatty acid synthase, and upregulated the levels of proteins involved in fatty acid β-oxidation, such as peroxisome proliferator-activated receptor α (PPARα), peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α), carnitine palmitoyltransferase 1α, acyl-CoA oxidase 1 and uncoupling protein 2, as well as the upstream mediators Sirt1 and AMPKα in the livers of HFD-fed mice. In vitro, LB100 alleviated FFA-induced lipid accumulation in L02 cells through the AMPK/Sirt1 signaling pathway. Further studies showed that the curative effect of LB100 on lipid accumulation was abolished by inhibiting AMPKα in L02 cells.CONCLUSIONPP2A inhibition by LB100 significantly ameliorates hepatic steatosis by regulating hepatic lipogenesis and fatty acid oxidation via the AMPK/Sirt1 pathway. LB100 may be a potential therapeutic agent for NAFLD.

Protective effects of nicotinamide mononucleotide against oxidative stress-induced PC12 cell death via mitochondrial enhancement

Oxidative stress is involved in most neurodegenerative diseases. Although it has been reported that the NAD+ precursor nicotinamide mononucleotide (NMN) improves symptoms in some oxidative stress-associated disease models, the detailed mechanisms have yet to be elucidated. In this study, we hypothesized that NMN attenuates oxidative stress-induced cell damage via sirtuin activation and increased numbers of mitochondria. To investigate whether NMN can protect neuronal cells from oxidative stress via the enhancement of mitochondrial function, we used PC12 cells treated with 6-hydroxydopamine (6-OHDA) or hydrogen peroxide (H2O2) as oxidative stress models. With regard to cytoprotective effects, pretreatment with NMN significantly reduced cell death induced by these stressors. These protective effects were attenuated by the sirtuin inhibitor, sirtinol, and knock-down of the peroxisome proliferator-activated receptor gamma coactivator-1α (PGC1α), which activates mitochondrial biogenesis. To clarify if NMN increased mitochondria, intracellular mitochondria were quantified using cytometric analysis. NMN clearly increased the numbers of intracellular mitochondria, and this increase was attenuated by sirtinol. Moreover, we quantified the mitochondria-associated proteins Sirt3 and superoxide dismutase 2 (SOD2) and found that treatment with NMN increased these proteins. We conclude that NMN protects neuronal cells from oxidative stress via sirtuin activation followed by mitochondrial enhancement.