Receptor Gamma Coactivator 1-alpha Research Articles

PGC-1α activation boosts exercise-dependent cellular response in the skeletal muscle

The role of Peroxisome proliferator-activated receptor-gamma coactivator alpha (PGC-1α) in fat metabolism is not well known. In this study, we compared the mechanisms of muscle-specific PGC-1α overexpression and exercise-related adaptation-dependent fat metabolism. PGC-1α trained (PGC-1α Ex) and wild-trained (wt-ex) mice were trained for 10 weeks, five times a week at 30 min per day with 60 percent of their maximal running capacity. The PGC-1α overexpressed animals exhibited higher levels of Fibronectin type III domain-containing protein 5 (FNDC5), 5' adenosine monophosphate-activated protein kinase alpha (AMPK-α), the mammalian target of rapamycin (mTOR), Sirtuin 1 (SIRT1), Lon protease homolog 1 (LONP1), citrate synthase (CS), succinate dehydrogenase complex flavoprotein subunit A (SDHA), Mitofusin-1 (Mfn1), endothelial nitric oxide synthase (eNOS), Hormone-sensitive lipase (HSL), adipose triglyceride lipase (ATGL), G protein-coupled receptor 41 (GPR41), and Phosphatidylcholine Cytidylyltransferase 2 (PCYT2), and lower levels of Sirtuin 3 (SIRT3) compared to wild-type animals. Exercise training increased the protein content levels of SIRT1, HSL, and ATGL in both the wt-ex and PGC-1α trained groups. PGC-1α has a complex role in cellular signaling, including the upregulation of lipid metabolism-associated proteins. Our data reveals that although exercise training mimics the effects of PGC-1α overexpression, it incorporates some PGC-1α-independent adaptive mechanisms in fat uptake and cell signaling.

Aldehyde Dehydrogenase 2 Preserves Mitochondrial Function in the Ischemic Heart: A Redox-dependent Mechanism for AMPK Activation by Thioredoxin-1.

Aldehyde dehydrogenase 2 (ALDH2) protects the ischemic heart by activating adenosine 5'-monophosphate-activated protein kinase (AMPK) signaling. However, the molecular mechanisms linking ALDH2 and AMPK signaling are not fully understood. This study aimed to explore the potential mechanisms linking ALDH2 and AMPK in myocardial ischemic injury. An ischemic model was established by ligating the left anterior descending coronary artery in rats. The overexpression or knockdown of ALDH2 in H9c2 cells treated with oxygen-glucose deprivation was obtained through lentivirus infection. Transferase-mediated dUTP nick-end labeling was used to evaluate apoptosis in an ischemic rat model and oxygen-glucose deprivation cells. ALDH2 activity, mitochondrial oxidative stress markers, adenosine triphosphate, respiratory control ratio, and cell viability in H9c2 cells were evaluated using a biological kit and 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide. Protein expression of ALDH2 , 4-hydroxynonenal, thioredoxin-1 (Trx-1), and AMPK-proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) signaling pathway was detected through Western blotting. ALDH2 activation reduced ischemic-induced myocardial infarct size and apoptosis. ALDH2 protected mitochondrial function by enhancing mitochondrial respiratory control ratio and adenosine triphosphate production, alleviated mitochondrial oxidative stress, and suppressed myocardial apoptosis. Moreover, ALDH2 attenuated ischemia-induced oxidative stress and maintained Trx-1 levels by reducing 4-hydroxynonenal, thereby promoting AMPK-PGC-1α signaling activation. Inhibiting Trx-1 or AMPK abolished the cardioprotective effect of ALDH2 on ischemia. ALDH2 alleviates myocardial injury through increased mitochondrial biogenesis and reduced oxidative stress, and these effects were achieved through Trx1-mediating AMPK-PGC1-α signaling activation.

Rutaecarpine Mitigates Cognitive Impairment by Balancing Mitochondrial Function Through Activation of the AMPK/PGC1α Pathway.

Mitochondrial dysfunction plays a fundamental role in the pathogenesis of cognitive deficit. Rutaecarpine (Rut) is a natural alkaloid with anti-inflammatory and antioxidant properties. This study explored whether Rut treatment could enhance cognitive function by improving mitochondrial function and examined the potential mechanisms underlying this ameliorative effect. We used the Morris water maze and Y-maze tests to evaluate the behavioral effects of Rut in a mouse model of cognitive impairment induced by subcutaneous injection of D-galactose (D-gal). Furthermore, we assessed the effects of Rut on mitochondrial function using cell viability assays, flow cytometry, western blotting, biochemical analysis, and immunochemical techniques in vivo and in vitro. The results indicated Rut treatment attenuated cognitive deficits and mitochondrial dysfunction in the mouse model. Similarly, it maintained the balance of mitochondrial dynamics in neurocytes and reduced oxidative stress and mitochondrial apoptosis in the HT22 cell model. Moreover, we found that these protective effects were dependent on the activation of the AMP-activated protein kinase/proliferator-activated receptor gamma coactivator 1-alpha (AMPK/PGC1α) signaling pathway. Our data indicate that Rut treatment are sensitive to reversal cognitive deficits and mitochondrial dysfunction induced by D-gal; this suggests that Rut is a promising mitochondria-targeted therapeutic agent for treating cognitive impairment.

DMC (2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone) enhances exercise tolerance via the AMPK-SIRT1-PGC-1α pathway in mice fed a high-fat diet.

Obesity is caused by an imbalance between energy intake and energy expenditure. This study aimed to determine the effects and mechanisms of 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone (DMC) on exercise tolerance in high-fat diet (HFD)-fed mice. Male C57BL/6J mice were randomly divided into two categories (7 groups [n = 8]): sedentary (control [CON], HFD, 200 mg/kg DMC, and 500 mg/kg DMC) and swimming (HFD, 200 mg/kg DMC, and 500 mg/kg DMC). Except the CON group, all other groups were fed HFD with or without DMC intervention for 33 days. The swimming groups were subjected to exhaustive swimming (three sessions/week). Changes in swimming time, glucolipid metabolism, body composition, biochemical indicators, histopathology, inflammation, metabolic mediators, and protein expression were assessed. DMC combined with regular exercise improved endurance performance, body composition, glucose and insulin tolerance, lipid profile, and the inflammatory state in a dose-dependent manner. Further, DMC alone or combined with exercise could restore normal tissue morphology, reduce fatigue-associated markers, and boost whole-body metabolism and the protein expression of phospho-AMP-activated protein kinase alpha/total-AMP-activated protein kinase alpha (AMPK), sirtuin-1 (SIRT1), peroxisome-proliferator-activated receptor gamma coactivator 1alpha (PGC-1α), and peroxisome proliferator-activated receptor alpha in the muscle and adipose tissues of HFD-fed mice. DMC exhibits antifatigue effects by regulating glucolipid catabolism, inflammation, and energy homeostasis. Furthermore, DMC exerts a synergistic exercise-related metabolic effect via the AMPK-SIRT1-PGC-1α signaling pathway, suggesting that DMC is a potential natural sports supplement with mimicked or augmented exercise effects for obesity prevention.

PRDX6 Promotes Fatty Acid Oxidation via PLA2-Dependent PPARα Activation in Rats Fed High-Fat Diet.

Aims: Nonalcoholic fatty liver disease (NAFLD) is becoming the most common chronic liver disease globally, which is defined as an excess accumulation of fat caused by the imbalance of lipogenesis and lipid catabolism. Recently, increasing evidence suggests that peroxiredoxin 6 (PRDX6) is involved in the pathogenesis and progression of NAFLD. However, little is known regarding its role in liver lipid catabolism. Results: We found that PRDX6 level was significantly increased in liver tissues after high-fat diet (HFD) treatment. PRDX6 knockout (KO) exacerbated HFD-induced hepatic steatosis. PRDX6 KO did not affect messenger RNA (mRNA) and protein levels of peroxisome proliferator-activated receptor alpha (PPARα). However, PRDX6 KO decreased the mRNA and protein levels of carnitine palmitoyltransferase-1alpha (CPT-1α) and acyl-CoA oxidase 1 (ACOX1), the target genes of PPARα. PRDX6 KO also did not activate AMP-activated protein kinase (AMPK)α/proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α), the upstream signal of PPARα. However, PRDX6 KO reduces the levels of PPARα activators, the oxidized fatty acids (9- and 13-hydroxyoctadecadienoic acid) in HFD rats. More interestingly, PRDX6 promoted the production of oxidized fatty acids by hydrolyzing oxidized low-density lipoprotein (Ox-LDL), which depends on its phospholipase A2 (PLA2) activity. PRDX6 mutation on its PLA2 and its competitive phospholipase inhibitor inhibited the production of the oxidized fatty acids as well as the activation of PPARα. Furthermore, PRDX6 overexpression enhanced the transcriptional activation of PPARα. Innovation and Conclusion: This study elucidates for the first time the role of PLA2 enzyme activity of PRDX6 in fatty acid oxidation and reveals a novel mechanism of PRDX6 involved in liver steatosis. Antioxid. Redox Signal. 38, 1184-1200.

Anti-Obesity Effects of Metformin: A Scoping Review Evaluating the Feasibility of Brown Adipose Tissue as a Therapeutic Target.

Brown adipose tissue (BAT) is increasingly recognized as the major therapeutic target to promote energy expenditure and ameliorate diverse metabolic complications. There is a general interest in understanding the pleiotropic effects of metformin against metabolic complications. Major electronic databases and search engines such as PubMed/MEDLINE, Google Scholar, and the Cochrane library were used to retrieve and critically discuss evidence reporting on the impact of metformin on regulating BAT thermogenic activity to ameliorate complications linked with obesity. The summarized evidence suggests that metformin can reduce body weight, enhance insulin sensitivity, and improve glucose metabolism by promoting BAT thermogenic activity in preclinical models of obesity. Notably, this anti-diabetic agent can affect the expression of major thermogenic transcriptional factors such as uncoupling protein 1 (UCP1), nuclear respiratory factor 1 (NRF1), and peroxisome-proliferator-activated receptor gamma coactivator 1-alpha (PGC1-α) to improve BAT mitochondrial function and promote energy expenditure. Interestingly, vital molecular markers involved in glucose metabolism and energy regulation such as AMP-activated protein kinase (AMPK) and fibroblast growth factor 21 (FGF21) are similarly upregulated by metformin treatment in preclinical models of obesity. The current review also discusses the clinical relevance of BAT and thermogenesis as therapeutic targets. This review explored critical components including effective dosage and appropriate intervention period, consistent with the beneficial effects of metformin against obesity-associated complications.

L‐Citrulline Decreases LPS‐Induced Inflammation and Oxidative Stress in Newborn Rat Lungs

Introduction Extremely low birth weight infants have immature lungs at birth as well as low levels of anti-inflammatory and antioxidative defences, placing them at high risk of developing bronchopulmonary dysplasia (BPD). Adiponectin (APN) is produced by adipocytes and has potent anti-inflammatory and antioxidative properties, and anti-proliferative effects; APN levels are quite low in premature infants. We showed that exogenous APN markedly attenuated lipopolysaccharide (LPS)-induced lung injury (Ivanovska et al. 2020) in newborn rats. Recombinant APN is not available for human use; however, L-citrulline (L-CIT) increases APN gene expression in adult rats (Joffin et al., 2015) and upregulates expression of peroxisome proliferator-activated receptor-gamma coactivator alpha (PGC-1α). PGC-1α is a master coactivator of genes involved in mitochondrial biogenesis, inflammation and oxidative stress. L-CIT levels are also low in premature infants. Thus, we sought to determine the effect of exogenous L-CIT on LPS-induced changes in protein expression of PGC-1α, APN, APN receptors (AdipoR1/2), cytokines, and superoxide dismutase (SOD) in lung and pulmonary artery smooth muscle cells (PASMC) homogenates, and on LPS-induced changes of intracellular ROS levels in PASMC. Methods in-vivo: Sprague Dawley rat pups were treated with L-CIT (2.5 g/kg) or saline intraperitoneally from postnatal day (PND) 1-5. On PND 5, intra-pharyngeal LPS (5mg/kg) or saline was given to L-CIT (n=4-6) or saline (n=4-6) treated animals; pups were euthanized 24 h after LPS treatment and lungs were removed and processed for western blot. In-vitro: PASMCisolated from PND 4 rats were treated with L-CIT (4 mM/ml), LPS (5μg/ml) and a combination of the two, for 3 h; cells were harvested and processed for protein expression (n=4 replicate experiments). PASMC were assayed for the level of LPS-induced intracellular ROS with fluorescence dye in the presence and absence of blocker for PGC-1α (SR 18292) Results In vivo, L-CIT, in the presence of LPS, increased lung protein expression of APN (1.36-fold), AdipoR1/2 (2-fold), PGC-1α (1.8-fold), phosphorylated AMP-kinase (2.1-fold), SOD1 (2.3-fold), SOD2 (1.7-fold), SOD3 (1.43-fold), and decreased tumor necrosis factor α (1.2-fold), and interleukin-8 (1.28-fold) compared to saline and LPS treated animals (p<0.05 L-CIT+LPS vs saline+LPS for all proteins). In vitro, in the presence of LPS, L-CIT increased PASMC protein expression of PGC-1α (1.55-fold), SOD1 (2-fold), SOD2 (1.57-fold), and SOD3 (2.2-fold) compared to cells only exposed to LPS (p<0.05; L-CIT+LPS vs medium+LPS). L-CIT decreased LPS-induced ROS production in PASMC, an effect that was inhibited in the presence of PGC-1α blocker. Conclusion L-CIT upregulates APN signaling in presence of LPS and decreases LPS-induced lung inflammation and oxidative stress in newborn rats through activation of PGC1-α. The translational significance of these findings warrants further clinical studies of the L-CIT potential preventative/curative benefit in BPD.

Maternal High Fat Diet and Diabetes Disrupts Transcriptomic Pathways That Regulate Cardiac Metabolism and Cell Fate in Newborn Rat Hearts.

Background: Children born to diabetic or obese mothers have a higher risk of heart disease at birth and later in life. Using chromatin immunoprecipitation sequencing, we previously demonstrated that late-gestation diabetes, maternal high fat (HF) diet, and the combination causes distinct fuel-mediated epigenetic reprogramming of rat cardiac tissue during fetal cardiogenesis. The objective of the present study was to investigate the overall transcriptional signature of newborn offspring exposed to maternal diabetes and maternal H diet.Methods: Microarray gene expression profiling of hearts from diabetes exposed, HF diet exposed, and combination exposed newborn rats was compared to controls. Functional annotation, pathway and network analysis of differentially expressed genes were performed in combination exposed and control newborn rat hearts. Further downstream metabolic assessments included measurement of total and phosphorylated AKT2 and GSK3β, as well as quantification of glycolytic capacity by extracellular flux analysis and glycogen staining.Results: Transcriptional analysis identified significant fuel-mediated changes in offspring cardiac gene expression. Specifically, functional pathways analysis identified two key signaling cascades that were functionally prioritized in combination exposed offspring hearts: (1) downregulation of fibroblast growth factor (FGF) activated PI3K/AKT pathway and (2) upregulation of peroxisome proliferator-activated receptor gamma coactivator alpha (PGC1α) mitochondrial biogenesis signaling. Functional metabolic and histochemical assays supported these transcriptome changes, corroborating diabetes- and diet-induced cardiac transcriptome remodeling and cardiac metabolism in offspring.Conclusion: This study provides the first data accounting for the compounding effects of maternal hyperglycemia and hyperlipidemia on the developmental cardiac transcriptome, and elucidates nuanced and novel features of maternal diabetes and diet on regulation of heart health.

Spermidine alleviates cardiac aging by improving mitochondrial biogenesis and function.

Polyamines have been shown to delay cellular and organismal aging and to provide cardiovascular protection in humans. Because age-related cardiovascular dysfunction is often accompanied by impaired mitochondrial biogenesis and function, we explored the ability of spermidine (SPD), a major mammalian polyamine, to attenuate cardiac aging through activation of mitochondrial biogenesis. Cardiac polyamine levels were reduced in aged (24-month-old) rats. Six-week SPD supplementation restored cardiac polyamine content, preserved myocardial ultrastructure, and inhibited mitochondrial dysfunction. Immunoblotting showed that ornithine decarboxylase (ODC) and SPD/spermine N1-acetyltransferase (SSAT) were downregulated and upregulated, respectively, in the myocardium of older rats. These changes were paralleled by age-dependent downregulation of components of the sirtuin-1/peroxisome proliferator-activated receptor gamma coactivator alpha (SIRT1/PGC-1α) signaling pathway, an important regulator of mitochondrial biogenesis. SPD administration increased SIRT1, PGC-1α, nuclear respiratory factors 1 and 2 (NRF1, NRF2), and mitochondrial transcription factor A (TFAM) expression; decreased ROS production; and improved OXPHOS performance in senescent (H2O2-treated) cardiomyocytes. Inhibition of polyamine biosynthesis or SIRT1 activity abolished these effects. PGC-1α knockdown experiments confirmed that SPD activated mitochondrial biogenesis through SIRT1-mediated deacetylation of PGC-1α. These data provide new insight into the antiaging effects of SPD, and suggest potential applicability to protect against deterioration of cardiac function with aging.

The Expression of CNS-Specific PPARGC1A Transcripts Is Regulated by Hypoxia and a Variable GT Repeat Polymorphism

PPARGC1A encodes a transcriptional co-activator also termed peroxisome proliferator-activated receptor (PPAR) gamma coactivator 1-alpha (PGC-1α) which orchestrates multiple transcriptional programs. We have recently identified CNS-specific transcripts that are initiated far upstream of the reference gene (RG) promoter. The regulation of these isoforms may be relevant, as experimental and genetic studies implicated the PPARGC1A locus in neurodegenerative diseases. We therefore studied cis- and trans-regulatory elements activating the CNS promoter in comparison to the RG promoter in human neuronal cell lines. A naturally occurring variable guanidine thymidine (GT) repeat polymorphism within a microsatellite region in the proximal CNS promoter increases promoter activity in neuronal cell lines. Both the RG and the CNS promoters are activated by ESRRA, and the PGC-1α isoforms co-activate ESRRA on their own promoters suggesting an autoregulatory feedback loop. The proximal CNS, but not the RG, promoter is induced by FOXA2 and co-activated by PGC-1α resulting in robust activation. Furthermore, the CNS, but not the RG, promoter is targeted by the canonical hypoxia response involving HIF1A. Importantly, the transactivation by HIF1A is modulated by the size of the GT polymorphism. Increased expression of CNS-specific transcripts in response to hypoxia was observed in an established rat model, while RG transcripts encoding the full-length reference protein were not increased. These results suggest a role of the CNS region of the PPARGC1A locus in ischemia and warrant further studies in humans as the activity of the CNS promoter as well as its induction by hypoxia is subject to inter-individual variability due to the GT polymorphism.

Role of epicardial adipose tissue NPR-C in acute coronary syndrome

Background and aimsIt has been suggested that epicardial adipose tissue (EAT) thermogenesis plays a role in coronary artery disease (CAD). Recent evidence indicates that natriuretic peptide receptors (NPRs) are critical for thermogenesis. We determined the expression and signaling of NPRs in EAT in the context of CAD progression and their association with brown fat-related genes, such as uncoupling protein 1 (UCP1) and peroxisome proliferator-activated receptor gamma coactivator alpha (PGC1α). MethodsNPR-A, NPR-B and NPR-C mRNA and protein expression levels were analyzed in EAT and thoracic subcutaneous adipose tissue (SAT) from non-CAD (NCAD), stable CAD and acute coronary syndrome (ACS) patients. The associations of NPRs with thermogenic genes were also evaluated. ResultsThe EAT of ACS patients showed lower NPR-C gene and protein expression levels compared with that of stable CAD or NCAD patients. NPR-C mRNA expression in EAT also decreased as the number of injured arteries rose, and correlated positively with left ventricular ejection fraction and EAT PGC1α mRNA expression. EAT PGC1α and UCP1 gene expression levels also decreased in the ACS group. Linear and logistic regression models showed associations of EAT NPR-C mRNA levels with EAT PGC1α mRNA levels and the presence of ACS. Furthermore, the EAT of ACS patients showed reduced p38 mitogen-activated protein kinase (p38 MAPK) phosphorylation levels, which correlated positively with NPR-C protein levels. ConclusionsThe EAT of patients with ACS is characterized by decreased NPR-C, reduced UCP1 and PGC1α mRNA expression levels and reduced activation of the p38 MAPK pathway. The associations among the expression of EAT NPR-C and ACS, and brown fat markers suggest that NPR-C may play a role in ACS and in the regulation of EAT brown-like fat features in humans.

Pharmacological Inhibition of CCR2/5 Signaling Prevents and Reverses Alcohol-Induced Liver Damage, Steatosis, and Inflammation in Mice.

Kupffer cell and macrophage (MØ) activation contributes to steatosis, inflammation, and fibrosis in alcoholic liver disease (ALD). We found increased frequency of MØ, T cells, and expression of C-C chemokine receptor type 2 (Ccr2) and C-C chemokine receptor type 5 (Ccr5) in the livers of patients with ALD, and increased circulating chemokines, C-C chemokine ligand types 2 (CCL2), and C-C chemokine ligand types 5 (CCL5) in patients with alcoholic hepatitis. We hypothesized that inhibition of CCL2 signaling with the dual CCR2/5 inhibitor, cenicriviroc (CVC), would attenuate ALD. In a mouse model of ALD, liver injury (alanine aminotransferase [ALT]) and steatosis were prevented by CVC whether administered as "prevention" throughout the alcohol feeding or as "treatment" started after the development of ALD. Alcohol-induced increases in early liver fibrosis markers (sirius red, hydroxyproline, and collagen-1) were normalized by both modes of CVC administration. We found that prevention and treatment with CVC reversed alcohol-related increases in liver mRNA and protein expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and CCL2. CVC administration regimens prevented the increase in infiltrating MØ (F4/80lo CD11bhi ) and reduced proinflammatory Ly6Chi MØ in livers of alcohol-fed mice. CVC increased liver T-cell numbers and attenuated Il-2 expression without an effect on CD69+ or CD25+ T-cell expression. In vitro, CVC inhibited CCL2-induced increases in hepatocyte fatty acid synthase (Fasn) and adipose differentiation-related protein (Adrp), whereas it augmented acyl-coenzyme A oxidase 1 (Acox-1), proliferator-activated receptor gamma co-activator alpha (Pgc1α) and uncoupling protein 2 expression, suggesting mechanisms for attenuated hepatocyte steatosis. We found that CCL2 and CCL5 sensitized hepatocytes to lipopolysaccharide-induced liver injury (TNF-α, ALT, and lactate dehydrogenase release). Alcohol feeding induced apoptosis (poly ADP-ribose polymerase [PARP] and caspase-3 [CASP-3] cleavage) and pyroptosis (gasdermin D [GSDMD] cleavage) in livers, and CVC prevented both of these forms of cell death. Conclusion: Together, our data demonstrate preclinical evidence for CCR2/CCR5 inhibition with CVC as a potent intervention to ameliorate alcohol-induced steatohepatitis and liver damage.

Endotoxin regulates matrix genes increasing reactive oxygen species generation by intercellular communication between palmitate-treated hepatocyte and stellate cell.

Previous studies have shown that gut-derived bacterial endotoxins contribute in the progression of simple steatosis to steatohepatitis, although the mechanism(s) remains inaccurate to date. As hepatic stellate cells (HSC) play a pivotal role in the accumulation of excessive extracellular matrix (ECM), leading to collagen deposition, fibrosis, and perpetuation of inflammatory response, an in vitro model was developed to investigate the crosstalk between HSC and hepatocytes (human hepatoma cell) pretreated with palmitate. Bacterial lipopolysaccharide (LPS) stimulated HSC with phosphorylation of the p38 mitogen-activated protein kinase/NF-κB pathway, while several important pro-inflammatory cytokines were upregulated in the presence of hepatocyte-HSC. Concurrently, fibrosis-related genes were regulated by palmitate and the inflammatory effect of endotoxin where cells were more exposed or sensitive to reactive oxygen species (ROS). This interaction was accompanied by increased expression of the mitochondrial master regulator, proliferator-activated receptor gamma coactivator alpha, and a cytoprotective effect of the agent N-acetylcysteine suppressing ROS production, transforming growth factor-β1, and tissue inhibitor ofmetalloproteinase-1. In summary, our results demonstrate that pro-inflammatory mediators LPS-induced promote ECM rearrangement in hepatic cells transcriptionally committed to the regulation of genes encoding enzymes for fatty acid metabolism in light of differences that might require an alternative therapeutic approach targeting ROS regulation.

Effects of phosphorylation state on perilipin 5 localization and trafficking.

Perilipins are a family of five proteins found on the surface of lipid storage droplets in nearly all tissues. These proteins act as cofactors for lipases and scaffolding for other proteins involved in lipid metabolism. In addition to the lipid droplet surface, members of the perilipin family have been found in the cytosol, endoplasmic reticulum, plasma membrane and mitochondria. The localization of these proteins is in part determined by their phosphorylation state. Recently perilipin 5 has been shown to localize to the nucleus when phosphorylated by PKA on serine 155 and interact with the peroxisome proliferator‐activated receptor gamma coactivator alpha (PGC‐1a). In silico analysis of a phosphomimetic mutant (Ser155Asp) indicate that this site may contain a nuclear localization sequence. Using a CHO model cell line we observed that translocation to the nucleus could be stimulated by treatment with forskolin and isobutylmethylxanthine (IBMX) and occurred independent of treating cells with oleic acid to promote triacylglycerol deposition. We are currently investigating the affects of stimulating other phosphorylation pathways to determine if they also phosphorylate perilipin 5 and affect subcellular localization. These data have the potential to gain insights to the regulation of perilipin 5 trafficking into the nucleus and therefore interacting with PGC‐1a regulating mitochondrial biogenesis.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Ursolic acid and mechanisms of actions on adipose and muscle tissue: a systematic review.

This systematic review aimed at addressing the ursolic acid actions as an adjunctive treatment of the obesity-mediated metabolic abnormalities. To explore our aims, we used the literature search including clinical and animal studies using the Medline and Google Scholar (up to December 2015). Out of 63 screened studies, 17 presented eligibility criteria, such as the use of ursolic acid on adiposity, energy expenditure and skeletal muscle mass in mice and humans. In the literature, we found that several physiological and molecular mechanisms are implicated in the effects of ursolic acid on obesity, energy expenditure, hepatic steatosis, skeletal muscle mass loss and physical fitness, such as (1) increase of thermogenesis by modulation adipocyte transcription factors, activation of 5' adenosine monophosphate-activated protein kinase and overexpression of the uncoupling protein 1 thermogenic marker; (2) enhancement of skeletal muscle mass by activation in bloodstream growth hormone and insulin-like growth factor-1 concentrations secretion, as well as in the activation of mammalian target of rapamycin and inhibition of ring-finger protein-1; and (3) improvement of physical fitness by skeletal muscle proliferator-activated receptor gamma co-activator alpha and sirtuin 1 expression. Therefore, supplementation with ursolic acid may be an adjunctive therapy for prevention and treatment of obesity-mediated and muscle mass-mediated metabolic consequences.

Abstract 12289: The Nuclear Receptor NR4A1 Regulates Transcriptional Programs Involved in Cardiac Fuel Metabolism and Hypertrophic Growth

The transcriptional coregulators, peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1) alpha and beta, are inducible master regulators of mitochondrial biogenesis and metabolism. Studies in rodents and in humans have shown that expression and activity of PGC-1 coactivators is downregulated in the failing heart. Surprisingly, we found that adult mice with cardiac-specific deletion of the PGC-1alpha/beta genes exhibit relatively normal cardiac function despite a significant reduction in mitochondrial state 3 respiration, suggesting the existence of a compensatory energy metabolic pathway. Unbiased transcriptional profiling demonstrated upregulation of the orphan nuclear receptor NR4A1 (Nur77) and the related nuclear receptor NR4A3 (Nor1) in PGC-1 null hearts, consistent with an adaptive response to energetic stress. We found that expression of NR4A1 family members is induced in heart by a variety of physiological stress stimuli. In addition, activation of beta-adrenergic signaling with isoproterenol led to rapid and dramatic induction in the expression of all NR4A members in the mouse heart. To identify cardiac NR4A1 targets, total RNA-seq was performed in neonatal rat ventricular myocytes (NRVMs) overexpressing NR4A1. NR4A1 expression of genes involved in glucose uptake/utilization pathways and high energy phosphate transfer including Slc2a4 (Glut4), Eno3 (enolase 3), and Ckmt2 (mitochondrial creatinine kinase). Consistent with the transcriptomic changes, NR4A1 increased myocyte 2-deoxylglucose uptake and oxygen consumption rates (OCR) in these cells. Interestingly, the RNA-seq data also revealed that NR4A1 overexpression downregulated many cardiac pathologic hypertrophic markers such as ANF and BNP. NR4A1 overexpression also significantly inhibited phenylephrine-induced NRVM hypertrophy. Finally, NR4A1 knockout mice exhibit exuberant cardiac hypertrophy following chronic isoproterenol administration. Taken together, these data suggest NR4A1 serves as a stress-induced transcription factor that regulates fuel metabolism and cardiac remodeling. The long-term goal of this project is to determine if activation of this pathway holds therapeutic benefit in acute heart failure.

Dual effects of fibroblast growth factor 21 on hepatic energy metabolism.

The aim of this study was to investigate the mechanisms by which fibroblast growth factor 21 (FGF21) affects hepatic integration of carbohydrate and fat metabolism in Siberian hamsters, a natural model of adiposity. Twelve aged matched adult male Siberian hamsters maintained in their long-day fat state since birth were randomly assigned to one of two treatment groups and were continuously infused with either vehicle (saline; n=6) or recombinant human FGF21 protein (1 mg/kg per day; n=6) for 14 days. FGF21 administration caused a 40% suppression (P<0.05) of hepatic pyruvate dehydrogenase complex (PDC), the rate-limiting step in glucose oxidation, a 34% decrease (P<0.05) in hepatic acetylcarnitine accumulation, an index of reduced PDC flux, a 35% increase (P<0.05) in long-chain acylcarnitine content (an index of flux through β-oxidation) and a 47% reduction (P<0.05) in hepatic lipid content. These effects were underpinned by increased protein abundance of PD kinase-4 (PDK4, a negative regulator of PDC), the phosphorylated (inhibited) form of acetyl-CoA carboxylase (ACC, a negative regulator of delivery of fatty acids into the mitochondria) and the transcriptional co-regulators of energy metabolism peroxisome proliferator activated receptor gamma co-activator alpha (PGC1α) and sirtuin-1. These findings provide novel mechanistic basis to support the notion that FGF21 exerts profound metabolic benefits in the liver by modulating nutrient flux through both carbohydrate (mediated by a PDK4-mediated suppression of PDC activity) and fat (mediated by deactivation of ACC) metabolism, and therefore may be an attractive target for protection from increased hepatic lipid content and insulin resistance that frequently accompany obesity and diabetes.

Erythropoietin enhances mitochondrial biogenesis in cardiomyocytes exposed to chronic hypoxia through Akt/eNOS signalling pathway

In the paper by Qin et al. (2014), there were errors in Figure 1. The correct figure is reproduced here. Effects of silencing endothelial nitric oxide synthase (eNOS) gene with shRNA plasmid (A) H9c2 cardiomyocytes were successfully transfected with shRNA plasmid of eNOS, which presented with green fluorescence (200x, fluorescence microscope). (B) Comparison of mtDNA copy number between the cells treated only with 20 U/mL recombinant human erythropoietin (rhEPO) (EPO control) and those treated with 20 U/mL rhEPO and shRNA plamid (EPOþshRNA), based on the cytochrome c/b-actin ratio. (C) Comparison of peroxisome profilerator activated receptor gamma coactivator alpha (PGC-1a) mRNA expression, normalized by ribosomal protein L10A (RPL10A) mRNA. (D) Comparison of the expression and phosphorylation of endothelial nitric oxide synthase (eNOS). p-eNOS: phosphorylated eNOS. #P < 0.05 versus cells treated only with 20 U/mL rhEPO.

Erythropoietin enhances mitochondrial biogenesis in cardiomyocytes exposed to chronic hypoxia through Akt/eNOS signalling pathway

Adaptation of cardiomyocytes to chronic hypoxia in cyanotic patients remains unclear. Mitochondrial biogenesis is enhanced in myocardium from cyanotic patients, which is possibly an adaptive response. Erythropoietin (EPO) in blood and its receptor (EPOR) on cardiomyocytes are upregulated by chronic hypoxia, suggesting that EPO-EPOR interaction is increased, which is inferred to positively regulate mitochondrial biogenesis through protein kinase B (Akt)/endothelial nitric oxide synthase (eNOS) signalling pathway. H9c2 cardiomyocytes were exposed to hypoxia (1% O(2)) for 1 week and treated with different doses of recombinant human erythropoietin (rhEPO). Mitochondrial number, mitochondrial DNA (mtDNA) copy number and peroxisome proliferator activated receptor gamma coactivator alpha (PGC-1α) mRNA expression increased in a dose-dependent manner induced by rhEPO. Akt and eNOS were significantly phosphorylated by rhEPO. Both blocking Akt with Wortmannin and silencing eNOS expression with shRNA plasmid decreased the mtDNA copy number and PGC-1α mRNA expression induced by rhEPO. Blocking Akt was associated with the decreased phosphorylation of Akt and eNOS. RNA interference led to a reduction in the total and phosphorylated proteins of eNOS. Thus EPO enhances mitochondrial biogenesis in cardiomyocytes exposed to chronic hypoxia, at least partly through Akt/eNOS signalling, which might be an adaptive mechanism of cardiomyocytes associated with the increased EPO-EPOR interaction in patients with cyanotic congenital heart disease (CCHD).

Effects of Quercetin and EGCG on Mitochondrial Biogenesis and Immunity

To test the influence of 1000 mg of quercetin (Q) with or without 120 mg of epigallocatechin 3-gallate (EGCG), 400 mg of isoquercetin, and 400 mg of eicosapentaenoic acid and docosahexaenoic acid (Q-EGCG) on exercise performance, muscle mitochondrial biogenesis, and changes in measures of immunity and inflammation before and after a 3-d period of heavy exertion. Trained cyclists (N = 39) were randomized to placebo (P), Q, or Q-EGCG and ingested supplements in a double-blinded fashion for 2 wk before, during, and 1 wk after a 3-d period in which subjects cycled for 3 h x d(-1) at approximately 57% Wmax. Blood, saliva, and muscle biopsy samples were collected before and after 2 wk of supplementation and immediately after the exercise bout on the third day. Blood and saliva samples were also collected 14 h after exercise. Two-week supplementation resulted in a significant increase in plasma quercetin for Q and Q-EGCG and granulocyte oxidative burst activity (GOBA) in Q-EGCG. Immediately after the third exercise bout, significant decreases for C-reactive protein (CRP), and plasma interleukin 6 (IL-6) and interleukin 10 (IL-10) were measured in Q-EGCG compared with P. Granulocyte colony-stimulating factor and CRP were reduced in Q-EGCG 14 h after exercise. No group differences were measured in muscle messenger RNA expression for peroxisome proliferator-activated receptor gamma coactivator alpha, citrate synthase, or cytochrome c. Two-week supplementation with Q-EGCG was effective in augmenting GOBA andin countering inflammation after 3 d of heavy exertion in trained cyclists.