Diet Based on Pereskia aculeata Miller Flour Increases Muscle Volume and Modulates the Expression of Myokines in Mice Subjected to Resistance Training.

The study aimed to evaluate the effects of Pereskia aculeata Miller (ora-pro-nobis [OPN]) flour on body and biochemical parameters, thermogenic activity, and molecular expression of markers in the muscle tissue of mice subjected to resistance training (RT). Twelve mice were randomly assigned to two groups (n=6 animals/group): G1: control (Control) fed a standard diet + RT and G2: experimental (OPN) fed a diet based on OPN flour + RT. The RT consisted of a 6-week program using a vertical ladder combined with a fixed weight attached to the animal. Several parameters were measured, including assessment of body composition, biochemical markers, thermogenic activity, and molecular (mRNA expression of interleukin (IL)-6, fibronectin type III domain-containing protein 5 (FNDC5), peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), nuclear respiratory factor 1 (NRF1), and mitochondrial transcription factor A (TFAM). The OPN group exhibited a decrease in body weight and visceral adiposity, higher energy expenditure, and lipid oxidation rate. In addition, it was observed an increase in muscle volume and in mRNA expression levels of IL-6, FNDC5, PGC-1α, and TFAM. These findings suggest that OPN flour could be a nutritional option to enhance performance in RT.

Effects of gallic acid and physical training on liver damage, force, and anxiety in obese mice: Hepatic modulation of Sestrin 2 (SESN2) and PGC-α expression.

Obesity and overweight are multifactorial diseases affecting more than one-third of the world's population. Physical inactivity contributes to a positive energy balance and the onset of obesity. Exercise combined with a balanced diet is an effective non-pharmacological strategy to improve obesity-related disorders. Gallic acid (GA), is a natural endogenous polyphenol found in a variety of fruits, vegetables, and wines, with beneficial effects on energetic homeostasis. The present study aims to investigate the effects of exercise training on obese mice supplemented with GA. Animal experimentation was performed with male Swiss mice divided into five groups: ST (standard control), HFD (obese control), HFD + GA (GA supplement), HFD + Trained (training), and HFD + GA + Trained (GA and training). The groups are treated for eight weeks with 200 mg/kg/body weight of the feed compound and, if applicable, physical training. The main findings of the present study show that GA supplementation improves liver fat, body weight, adiposity, and plasma insulin levels. In addition, animals treated with the GA and a physical training program demonstrate reduced levels of anxiety. Gene expression analyses show that Sesn2 is activated via PGC-1α independent of the GATOR2 protein, which is activated by GA in the context of physical activity. These data are corroborated by molecular docking analysis, demonstrating the interaction of GA with GATOR2. The present study contributes to understanding the metabolic effects of GA and physical training and demonstrates a new hepatic mechanism of action via Sestrin 2 and PGC-1α.

Perilipin Isoforms and PGC-1α Are Regulated Differentially in Rat Heart during Pregnancy-Induced Physiological Cardiac Hypertrophy.

Background and Objectives: Perilipins 1-5 (PLIN) are lipid droplet-associated proteins that participate in regulating lipid storage and metabolism, and the PLIN5 isoform is known to form a nuclear complex with peroxisome proliferator-activated receptor-gamma coactivator 1-alpha (PGC-1α) to regulate lipid metabolism gene expression. However, the changes in PLIN isoforms' expression in response to pregnancy-induced cardiac hypertrophy are not thoroughly studied. The aim of this study was to quantify the mRNA expression of PLIN isoforms and PGC-1α along with total triacylglycerol (TAG) and cholesterol levels during late pregnancy and the postpartum period in the rat left ventricle. Materials and Methods: Female Sprague-Dawley rats were divided into three groups: non-pregnant, late pregnancy, and postpartum. The mRNA and protein levels were evaluated using quantitative RT-PCR and Western blotting, respectively. TAG and total cholesterol content were evaluated using commercial colorimetric methods. Results: The expression of mRNAs for PLIN1, 2, and 5 increased during pregnancy and the postpartum period. PGC-1α mRNA and protein expression increased during pregnancy and the postpartum period. Moreover, TAG and total cholesterol increased during pregnancy and returned to basal levels after pregnancy. Conclusions: Our results demonstrate that pregnancy upregulates differentially the expression of PLIN isoforms along with PGC-1α, suggesting that together they might be involved in the regulation of the lipid metabolic shift induced by pregnancy.

Lactate modulates cardiac gene expression in mice during acute physical exercise.

The aim of the present study was to verify the role of lactate as a signaling molecule in cardiac tissue under physiological conditions. C57BL6/J male mice were submitted to acute running bouts on a treadmill at different exercise intensities (30, 60, and 90% of maximal speed - Smax) under the effect of two doses (0.5 and 5 mM) of α-cyano-4-hydroxycynnamate (CINN), a blocker of lactate transporters. Cardiac lactate levels, activity of the enzymes of glycolytic [hexokinase (HK) and lactate dehydrogenase (LDH)] and oxidative metabolism [citrate synthase (CS)], and expression of genes also related to metabolism [LDH, nuclear factor erythroid 2-related factor 2 (NRF-2), cytochrome oxidase IV (COX-IV), and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α)] were evaluated. Elevated cardiac lactate levels were observed after high intensity running at 90% of Smax, which were parallel to increased activity of the HK and CS enzymes and mRNA levels of PGC-1α and COX-IV. No changes were observed in cardiac lactate levels in mice running at lower exercise intensities. Interestingly, prior intraperitoneal administration (15 min) of CINN (0.5 mM) significantly reduced cardiac lactate concentration, activities of HK and CS, and mRNA levels of PGC-1α and COX-IV in mice that ran at 90% of Smax. In addition, cardiac lactate levels were significantly correlated to both PGC-1α and COX-IV cardiac gene expression. The present study provides evidence that cardiac lactate levels are associated to gene transcription during an acute bout of high intensity running exercise.

Breastfeeding undernutrition changes iBAT-involved thermogenesis protein expression and leads to a lean phenotype in adult rat offspring.

Nutritional insults early in life have been associated with metabolic diseases in adulthood. We aimed to evaluate the effects of maternal food restriction during the suckling period on metabolism and interscapular brown adipose tissue (iBAT) thermogenically involved proteins in adult rat offspring. Wistar rats underwent food restriction by 50% during the first two-thirds of lactation (FR50 group). Control rats were fed ad libitum throughout lactation (CONT group). At birth, the litter size was adjusted to eight pups, and weaning was performed at 22 days old. Body weight and food and water intake were assessed every two days. High- (HCD, 4,589 cal) and normal-caloric diet (NCD, 3,860 cal) preferences, as well as food intake during the dark part of the cycle, were assessed. At 100 days old, the rats were euthanized, and blood and tissues were removed for further analyses. Adult FR50 rats, although hyperphagic and preferring to eat HCD (P<.001), were leaner (P<.001) than the CONT group. The FR50 rats, were normoglycemic (P=.962) and had hypertriglyceridemia (P<.01). In addition, the FR50 rats were dyslipidemic (P<.01), presenting with a high atherogenic risk by the Castelli indexes (P<.01), had a higher iBAT mass (P<.01), fewer ß3 adrenergic receptors (ß3-AR, P<.05) and higher iBAT expression of uncoupled protein 1 (UCP1, P<.05) and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α, P<.001) than the CONT rats. In conclusion, maternal food restriction during early breastfeeding programs rat offspring to have a lean phenotype, despite hyperphagia, and increased iBAT UCP1 and PGC-1α protein expression.

Placental Insulin/IGF-1 Signaling, PGC-1α, and Inflammatory Pathways Are Associated With Metabolic Outcomes at 4-6 Years of Age: The ECHO Healthy Start Cohort.

An adverse intrauterine environment is associated with the future risk of obesity and type 2 diabetes. Changes in placental function may underpin the intrauterine origins of adult disease, but longitudinal studies linking placental function with childhood outcomes are rare. Here, we determined the abundance and phosphorylation of protein intermediates involved in insulin signaling, inflammation, cortisol metabolism, protein glycosylation, and mitochondrial biogenesis in placental villus samples from healthy mothers from the Healthy Start cohort. Using MANOVA, we tested the association between placental proteins and offspring adiposity (fat mass percentage) at birth (n = 109) and infancy (4-6 months, n = 104), and adiposity, skinfold thickness, triglycerides, and insulin in children (4-6 years, n = 66). Placental IGF-1 receptor protein was positively associated with serum triglycerides in children. GSK3ß phosphorylation at serine 9, a readout of insulin and growth factor signaling, and the ratio of phosphorylated to total JNK2 were both positively associated with midthigh skinfold thickness in children. Moreover, peroxisome proliferator-activated receptor γ coactivator (PGC)-1α abundance was positively associated with insulin in children. In conclusion, placental insulin/IGF-1 signaling, PGC-1α, and inflammation pathways were positively associated with metabolic outcomes in 4- to 6-year-old children, identifying a novel link between placental function and long-term metabolic outcomes.

PPARGC1A Gene Promoter Methylation as a Biomarker of Insulin Secretion and Sensitivity in Response to Glucose Challenges.

Methylation in CpG sites of the PPARGC1A gene (encoding PGC1-α) has been associated with adiposity, insulin secretion/sensitivity indexes and type 2 diabetes. We assessed the association between the methylation profile of the PPARGC1A gene promoter gene in leukocytes with insulin secretion/sensitivity indexes in normoglycemic women. A standard oral glucose tolerance test (OGTT) and an abbreviated version of the intravenous glucose tolerance test (IVGTT) were carried out in n = 57 Chilean nondiabetic women with measurements of plasma glucose, insulin, and C-peptide. Bisulfite-treated DNA from leukocytes was evaluated for methylation levels in six CpG sites of the proximal promoter of the PPARGC1A gene by pyrosequencing (positions -816, -783, -652, -617, -521 and -515). A strong correlation between the DNA methylation percentage of different CpG sites of the PPARGC1A promoter in leukocytes was found, suggesting an integrated epigenetic control of this region. We found a positive association between the methylation levels of the CpG site -783 with the insulin sensitivity Matsuda composite index (rho = 0.31; p = 0.02) derived from the OGTT. The CpG hypomethylation in the promoter position -783 of the PPARGC1A gene in leukocytes may represent a biomarker of reduced insulin sensitivity after the ingestion of glucose.

Effects of short-term high-intensity interval and continuous exercise training on body composition and cardiac function in obese sarcopenic rats.

AIM: We investigated the effects of high-intensity interval and continuous short-term exercise on body composition and cardiac function after myocardial ischemia-reperfusion injury (IRI) in obese rats. METHODS: Rats fed with a standard chow diet (SC) or high-fat diet (HFD) for 20 weeks underwent systolic blood pressure (SBP), glycemia and dual-energy X-ray absorptiometry analyses. Then, animals fed with HFD were subdivided into three groups: sedentary (HFD-SED); moderate-intensity continuous training (HFD-MICT); and high-intensity interval training (HFD-HIIT). Exercised groups underwent four isocaloric aerobic exercise sessions, in which HFD-MICT maintained the intensity continuously and HFD-HIIT alternated it. After exercise sessions, all groups underwent global IRI and myocardial infarct size (IS) was determined histologically. Fat and muscle mass were weighted, and protein levels involved in muscle metabolism were assessed in skeletal muscle. RESULTS: HFD-fed versus SC-fed rats reduced lean body mass by 31% (P < 0.001), while SBP, glycemia and body fat percentage were increased by 10% (P = 0.04), 30% (P = 0.006) and 54% (P < 0.001); respectively. HFD-induced muscle atrophy was restored in exercised groups, as only HFD-SED presented lower gastrocnemius (32%; P = 0.001) and quadriceps mass (62%; P < 0.001) than SC. PGC1-α expression was 2.7-fold higher in HFD-HIIT versus HFD-SED (P = 0.04), whereas HFD-HIIT and HFD-MICT exhibited 1.7-fold increase in p-mTORSer2481 levels compared to HFD-SED (P = 0.04). Although no difference was detected among groups for IS (P = 0.30), only HFD-HIIT preserved left-ventricle developed pressure after IRI (+0.7 mmHg; P = 0.9). SIGNIFICANCE: Short-term exercise, continuous or HIIT, restored HFD-induced muscle atrophy and increased mTOR expression, but only HIIT maintained myocardial contractility following IRI in obese animals.

Epidemiology and pathophysiology of the association between NAFLD and metabolically healthy or metabolically unhealthy obesity.

The prevalence of nonalcoholic fatty liver disease (NAFLD) is continuing to rise in many countries, paralleling the epidemic of obesity worldwide. In the last years, the concept of metabolically healthy obesity [MHO, generally defined as obesity without metabolic syndrome (MetS)] has raised considerable scientific interest. MHO is a complex phenotype with risks intermediate between metabolically healthy individuals with normal-weight (NWMH) and patients who are obese and metabolically unhealthy (MUO, i.e. obesity with MetS). In this review we aimed to examine the association and pathophysiological link of NAFLD with MHO and MUO. Compared to NWMH individuals, patients with obesity, regardless of the presence of MetS features, are at higher risk of all-cause mortality and cardiovascular events. Moreover, MHO patients have a greater risk of NAFLD development and progression compared to NWMH individuals. However, this risk is generally lower than that of MUO patients, suggesting a stronger adverse effect of coexisting MetS disorders than obesity per se on the severity of NAFLD. Nevertheless, since MHO is a dynamic state (with a significant proportion of MHO subjects progressing to MUO over time) and NAFLD itself may predict the transition from MHO to MUO, we believe that any effort should be made to identify NAFLD in all obese individuals, although they appear to be "metabolically healthy". Future research is needed to better understand the role of NAFLD and other pathogenic factors potentially involved in the transition from MHO to MUO and to elucidate how this transition may affect the presence and severity of NAFLD.

PPARGC1A promoter DNA-methylation level and glucose metabolism in Ecuadorian women with Turner syndrome.

OBJECTIVES: Reduced gene expression of PPARGC1A in subjects with insulin resistance (IR) has been reported. Insulin resistance occurs early on the course of Turner syndrome (TS). The main objective of this study was to evaluate the relationship between PPARGC1A promoter DNA methylation status in lymphocytes and insulin sensitivity and secretion in Ecuadorian females with TS. METHODS: We examined a cohort of 34 Ecuadorian patients with TS along with a sex-, age- and BMI-matched reference group. All subjects received a standard 75 g oral glucose tolerance test. Insulin resistance and secretion indices were calculated. The PPARGC1A methylated DNA/unmethylated DNA ratio and mitochondrial content (mtDNA/nDNA ratio) were further determined. RESULTS: Notably, the PPARGC1A DNA methylation level was significantly higher in TS subjects than the reference group and correlated with IR indices. Conversely, mitochondrial content was significantly lower in the study group than healthy controls and negatively correlated with the PPARGC1A methylated DNA/unmethylated DNA ratio in TS individuals. PPARGC1A promoter DNA methylation status contributed to 20% of the total variability in Homeostasis Model Assessment for Insulin Resistance (HOMA-IR) independently of BMI or age in TS subjects. CONCLUSIONS: Our collective findings suggest that expression of PPARGC1A and lower mitochondrial number affect the metabolic phenotype in TS subjects.

Influence of pre-pregnancy body mass index (p-BMI) and gestational weight gain (GWG) on DNA methylation and protein expression of obesogenic genes in umbilical vein.

Understanding the regulatory mechanisms that affect obesogenic genes expression in newborns is essential for early prevention efforts, but they remain unclear. Our study aimed to explore whether the maternal p-BMI and GWG were associated with regulatory single-locus DNA methylation in selected obesogenic genes. For this purpose, DNA methylation was assayed by Methylation-Sensitive High Resolution Melting (MS-HRM) technique and Sanger allele-bisulfite sequencing in fifty samples of umbilical vein to evaluate glucosamine-6-phosphate deaminase 2 (GNPDA2), peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC1α), and leptin receptor (LEPR) genes. Correlations between DNA methylation levels and indicators of maternal nutritional status were carried out. Western blotting was used to evaluate protein expression in extracts of the same samples. Results indicated that GNPDA2 and PGC1α genes have the same level of DNA methylation in all samples; however, a differential DNA methylation of LEPR gene promoter was found, correlating it with GWG and this correlation is unaffected by maternal age or unhealthy habits. Furthermore, leptin receptor (Lep-Rb) was upregulated in samples that showed the lowest levels of DNA methylation. This study highlights the association between poor GWG and adjustments on obesogenic genes expression in newborn tissues with potential consequences for development of obesity in the future.

TGF-ß1 downregulation in the hypothalamus of obese mice through acute exercise.

Obesity and aging lead to abnormal transforming growth factor-ß1 (TGF-ß1) signaling in the hypothalamus, triggering the imbalance on glucose metabolism and energy homeostasis. Here, we determine the effect of acute exercise on TGF-ß1 expression in the hypothalamus of two models of obesity in mice. The bioinformatics analysis was performed to evaluate the correlation between hypothalamic Tgf-ß1 messenger RNA (mRNA) and genes related to thermogenesis in the brown adipose tissue (BAT) by using a large panel of isogenic BXD mice. Thereafter, leptin-deficient (ob/ob) mice and obese C57BL/6 mice fed on a high-fat diet (HFD) were submitted to the acute exercise protocol. Transcriptomic analysis by using BXD mouse reference population database revealed that hypothalamic Tgf-ß1 mRNA is negatively correlated with genes related to thermogenesis in brown adipose tissue of BXD mice, such as peroxisome proliferator-activated receptor gamma coactivator and is positively correlated with respiratory exchange ratio. In agreement with these results, leptin-deficient (ob/ob) and HFD-fed mice displayed high levels of Tgf-ß1 mRNA in the hypothalamus and reduction of Pgc1α mRNA in BAT. Interestingly, an acute exercise session reduced TGF-ß1 expression in the hypothalamus, increased Pgc1α mRNA in the BAT and reduced food consumption in obese mice. Our results demonstrated that acute physical exercise suppressed hypothalamic TGF-ß1 expression, increasing Pgc1α mRNA in BAT in obese mice.

Strength training and aerobic exercise alter mitochondrial parameters in brown adipose tissue and equally reduce body adiposity in aged rats.

With aging, there is a reduction in mitochondrial activity, and several changes occur in the body composition, including increased adiposity. The dysfunction of mitochondrial activity causes changes and adaptations in tissue catabolic characteristics. Among them, we can mention brown adipose tissue (BAT). BAT's main function is lipid oxidation for heat production, hence playing a role in adaptive thermogenesis induced by environmental factors such as exercise. It is known that exercise causes a series of metabolic changes, including loss body fat; however, there is still no consensus in the academic community about whether both strength and aerobic exercise equally reduces adiposity. Therefore, this study aimed to evaluate the effects of strength training and aerobic exercise regimes on adiposity, proteins regulating mitochondrial activity, and respiratory complexes in BAT of old rats. The rats were divided in two control groups: young control (YC; N = 5), and old control (OC; N = 5), and two exercise groups: strength training (OST; N = 5), and aerobic treadmill training (OAT; N = 5). Rats were subjected to an 8-week exercise regime, and their body composition parameters were evaluated (total body weight, adiposity index, and BAT weight). In addition, mitochondrial biogenesis proteins (PGC-1α, SIRT1, and pAMPK) and respiratory chain activity (complexes I, II/III, III, and IV) were evaluated. Results showed that OST and OAT exercise protocols significantly increased the mitochondrial regulatory molecules and respiratory chain activity, while body fat percentage and adiposity index significantly decreased. Taken together, both OST and OAT exercise increased BAT weight, activity of respiratory complexes, and regulatory proteins in BAT and equally reduced body adiposity.

Fish Oil Protects Wild Type and Uncoupling Protein 1-Deficient Mice from Obesity and Glucose Intolerance by Increasing Energy Expenditure.

SCOPE: The mechanisms and involvement of uncoupling protein 1 (UCP1) in the protection from obesity and insulin resistance induced by intake of a high-fat diet rich in omega-3 (n-3) fatty acids are investigated. METHODS AND RESULTS: C57BL/6J mice are fed either a low-fat (control group) or one of two isocaloric high-fat diets containing either lard (HFD) or fish oil (HFN3) as fat source and evaluated for body weight, adiposity, energy expenditure, glucose homeostasis, and inguinal white and interscapular brown adipose tissue (iWAT and iBAT, respectively) gene expression, lipidome, and mitochondrial bioenergetics. HFN3 intake protected from obesity, glucose and insulin intolerances, and hyperinsulinemia. This is associated with increased energy expenditure, iWAT UCP1 expression, and incorporation of n-3 eicosapentaenoic and docosahexaenoic fatty acids in iWAT and iBAT triacylglycerol. Importantly, HFN3 is equally effective in reducing body weight gain, adiposity, and glucose intolerance and increasing energy expenditure in wild-type and UCP1-deficient mice without recruiting other thermogenic processes in iWAT and iBAT, such as mitochondrial uncoupling and SERCA-mediated calcium and creatine-driven substrate cyclings. CONCLUSION: Intake of a high-fat diet rich in omega-3 fatty acids protects both wild-type and UCP1-deficient mice from obesity and insulin resistance by increasing energy expenditure through unknown mechanisms.

Decreased PGC1- α levels and increased apoptotic protein signaling are associated with the maladaptive cardiac hypertrophy in hyperthyroidism.

Hyperthyroidism can lead to the activation of proteins which are associated with inflammation, apoptosis, hypertrophy, and heart failure. This study aimed to explore the inflammatory and apoptotic proteins involved in the hyperthyroidism-induced cardiac hypertrophy establishment. Male Wistar rats were divided into control and hyperthyroid (12 mg/L L-thyroxine, in drinking water for 28 days) groups. The expression of inflammatory and apoptotic signaling proteins was quantified in the left ventricle by Western blot. Hyperthyroidism was confirmed by evaluation of T3 and T4 levels, as well as cardiac hypertrophy development. There was no change in the expression of HSP70, HIF1-α, TNF-α, MyD88, p-NFκB, NFκB, p-p38, and p38. Reduced expression of p53 and PGC1-α was associated with increased TLR4 and decreased IL-10 expression. Decreased Bcl-2 expression and increased Bax/Bcl-2 ratio were also observed. The results suggest that reduced PGC1-α and IL-10, and elevated TLR4 proteins expression could be involved with the diminished mitochondrial biogenesis and anti-inflammatory response, as well as cell death signaling, in the establishment of hyperthyroidism-induced maladaptive cardiac hypertrophy.

Genetic susceptibility to pre diabetes mellitus and related association with obesity and physical fitness components in Mexican-Mestizos.

Pre diabetes mellitus (pre-DM) is considered an early-reversible condition that can progress to Type 2 diabetes mellitus (T2DM) which is the main cause of death for adult Mexican population. Gene variants influencing fasting glucose levels may constitute helpful tool for prevention purposes in pre-DM condition. Physically active Mexican-Mestizo adults (n=565) were genotyped for 6 single nucleotide polymorphisms (SNPs) (ADIPOQ rs2241766, ACSL1 rs9997745, LIPC rs1800588, PPARA rs1800206, PPARG rs1801282 and PPARGC1A rs8192678) related to lipid and carbohydrate metabolism. Fasting glucose was measured and values classified as pre-DM (≥100mg/dL) or normal fasting glucose. Logistic models were used to test associations between pre-DM condition and SNPs, and interaction with Body Mass Index (BMI) and physical fitness components. The A allele of ASCL1 rs9997745 conferred increased risk (OR=3.39, p=0.001) of pre-DM which is modulated by BMI. The A allele of the PPARGC1A rs8192678 showed significant SNP*BMI (OR=1.10, p=0.008) interaction effect for pre-DM risk, meaning that obese subjects showed higher pre-DM risk but normal weight subjects showed lower risk. The effect increased with age and was attenuated by higher cardiorespiratory values. We found that both ACSL1 rs9997745 and PPARGC1A rs8192678 are associated with pre-DM, and that BMI significantly modified their association.

Deficient mitochondrial biogenesis in IL-2 activated NK cells correlates with impaired PGC1-α upregulation in elderly humans.

Immunosenescence has been described as age-associated changes in the immune function which are thought to be responsible for the increased morbidity with age. Human Natural Killer (NK) cells are a specialized heterogeneous subpopulation of lymphocytes involved in immune defense against tumor and microbial diseases. Interestingly, aging-related NK cell dysfunction is associated with features of aging such as tumor incidence, reduced vaccination efficacy, and short survival due to infection. It is known that NK cell effector functions are critically dependent on cytokines and metabolic activity. Our aim was to determine whether there is a difference in purified human NK cell function in response to high concentration of IL-2 between young and elder donors. Here, we report that the stimulation of human NK cells with IL-2 (2000 U/mL) enhance NK cell cytotoxic activity from both young and elderly donors. However, while NK cells from young people responded to IL-2 signaling by increasing mitochondrial mass and mitochondrial membrane potential, no increase in these mitochondrial functional parameters was seen in purified NK cells from elderly subjects. Moreover, as purified NK cells from the young exhibited an almost three-fold increase in PGC-1α expression after IL-2 (2000 U/mL) stimulation, PGC-1α expression was inhibited in purified NK cells from elders. Furthermore, this response upon PGC-1α expression after IL-2 stimulation promoted an increase in ROS production in NK cells from elderly humans, while no increase in ROS production was observed in NK cells of young donors. Our data show that IL-2 stimulates NK cell effector function through a signaling pathway which involves a PGC-1α-dependent mitochondrial function in young NK cells, however it seems that NK cells from older donors exhibit an altered IL-2 signaling which affects mitochondrial function associated with an increased production of ROS which could represent a feature of NK cell senescence.

A20 deubiquitinase controls PGC-1α expression in the adipose tissue.

BACKGROUND: Peroxisome proliferator-activated receptor γ coactivator- 1alpha (PGC-1α) plays an important role in whole body metabolism and, particularly in glucose homeostasis. Its expression is highly regulated and, small variations in tissue levels can have a major impact in a number of physiological and pathological conditions. Recent studies have shown that the ubiquitin/proteasome system plays a role in the control of PGC-1α degradation. METHODS: Here we evaluated the interaction of PGC-1α with the protein A20, which plays a dual-role in the control of the ubiquitin/proteasome system acting as a deubiquitinase and as an E3 ligase. We employed immunoprecipitation, quantitative real-time PCR and immunofluorescence staining to evaluate PGC-1α, A20, PPARγ and ubiquitin in the adipose tissue of humans and mice. RESULTS: In distinct sites of the adipose tissue, A20 binds to PGC-1α. At least in the subcutaneous fat of humans and mice the levels of PGC-1α decrease during obesity, while its physical association with A20 increases. The inhibition of A20 leads to a reduction of PGC-1α and PPARγ expression, suggesting that A20 acts as a protective factor against PGC-1α disposal. CONCLUSION: We provide evidence that mechanisms regulating PGC-1α ubiquitination are potentially involved in the control of the function of this transcriptional co-activator.

Role of NCoR1 in mitochondrial function and energy metabolism.

Mitochondrial number and shape are constantly changing in response to increased energy demands. The ability to synchronize mitochondrial pathways to respond to energy fluctuations within the cell is a central aspect of mammalian homeostasis. This dynamic process depends on the coordinated activation of transcriptional complexes to promote the expression of genes encoding for mitochondrial proteins. Recent evidence has shown that the nuclear corepressor NCoR1 is an essential metabolic switch which acts on oxidative metabolism signaling. Here, we provide an overview of the emerging role of NCoR1 in the transcriptional control of energy metabolism. The identification and characterization of NCoR1 as a central, evolutionary conserved player in mitochondrial function have revealed a novel layer of metabolic control. Defining the precise mechanisms by which NCoR1 acts on energy homeostasis will ultimately contribute towards the development of novel therapies for the treatment of metabolic diseases such as obesity and type 2 diabetes.

Metabolic studies of a patient harbouring a novel S487L mutation in the catalytic subunit of AMPK.

AMP-activated protein kinase (AMPK) regulates many different metabolic pathways in eukaryote cells including mitochondria biogenesis and energy homeostasis. Here we identify a patient with hypotonia, weakness, delayed milestones and neurological impairment since birth harbouring a novel homozygous mutation in the AMPK catalytic α-subunit 1, encoded by the PRKAA1 gene. The homozygous mutation p.S487L in isoform 1 present in the patient is in a cryptic residue for AMPK activity. In the present study, we performed the characterization of mitochondrial respiratory properties of the patient, in comparison to healthy controls, through the culture of skin fibroblasts in order to understand some of the cellular consequences of the PRKAA1 mutation. In these assays, mitochondrial respiratory complex I showed lower activity, which was followed by a decrement in the mtDNA copy number, which is a probable consequence of the lower expression of PGC-1α and PRKAA1 itself as measured in our quantitative PCRs experiments. Confirming the effect of the patient mutation in respiration, transfection of patient fibroblasts with wild type PRKAA1 partially restore complex I level. The preliminary clinic evaluations of the patient suggested a metabolic defect related to the mitochondrial respiratory function, therefore treatment with CoQ10 supplementation dose started four years ago and a clear improvement in motor skills and strength has been achieved with this treatment.