5-Aza-2'-deoxycytidine-mediated DNA hypomethylation with and without concurrent insulin resistance suppresses myotube mitochondrial capacity.

Type 2 diabetes is characterized by elevated blood glucose and reduced insulin sensitivity in target tissues. Moreover, reduced mitochondrial metabolism and expressional profile of genes governing mitochondrial metabolism (such as peroxisome proliferator-activated receptor gamma coactivator 1-alpha [PGC-1α]) are also reduced during insulin resistance. Epigenetic regulation via DNA methylation of genes including PGC-1α may contribute to diminished mitochondrial capacity, while hypomethylation of PGC-1α (such as that invoked by exercise) has been associated with increased PGC-1α expression and favorable metabolic outcomes. The purpose of the present report is to characterize the effects of DNA hypomethylation on myotube metabolism and expression of several related metabolic targets. C2C12 myotubes were treated with 5-Aza-2'-deoxycytidine (5-Aza) for either 24 or 72 h both with and without hyperinsulinemic-induced insulin resistance. Mitochondrial and glycolytic metabolism were measured via oxygen consumption and extracellular acidification rate, respectively. Metabolic gene and protein expression were assessed via quantitative real time polymerase chain reaction and western blot analysis, respectively. Though expression of PGC-1α and other related targets remained unaltered, insulin resistance and 5-Aza treatment significantly reduced mitochondrial metabolism. Similarly, peak glycolytic metabolism was diminished by 5-Aza-treated cells, while basal glycolytic metabolism was unaltered. 5-Aza also reduced the expression of branched-chain amino acid (BCAA) catabolic components, however BCAA utilization was enhanced during insulin resistance with 5-Aza treatment. Together the present work provides proof-of-concept evidence of the potential role of DNA methylation in the regulation of mitochondrial metabolism and the potential interactions with insulin resistance in a model of skeletal muscle.

Fenofibrate mildly stimulates browning-associated expression in white adipose tissues of young but not old male rats.

The aim of this study was to examine the effects of the hypolipemic drug fenofibrate (FF) and aging on the expression of factors/enzymes involved in brown adipose tissue (BAT) function and browning of white adipose tissue epididymal (eWAT) and subcutaneous (sWAT) depots. Young-adult and old male Wistar rats were fed standard chow (control) or supplemented with 0.1% or 0.5% FF for 30 days. Tissue samples were analysed for gene expression and protein content, and stained with Oil Red O or hematoxylin and eosin. In BAT of young rats, 0.5% FF increased only Cbp/p300 interacting transactivator with Glu/Asp rich carboxy-terminal domain 1 (CITED1) protein content and Fgf21 and Gpr109A mRNA expression. The expression of oxidative metabolism related genes (Pgc1α, Cpt1b, Mcad) decreased after 0.5% FF. In BAT of old rats, FF did not affect UCP1 and CITED1 content and had little effect on gene expression. Oil Red O staining of BAT revealed no changes in lipid droplet area upon treatment in either age group. In eWAT of young rats, 0.1FF elevated UCP1 protein content and Ucp1, Pgc-1α, and Mcad expression, whereas 0.5% FF increased PPARα content and Pgc-1α, Cpt1b, Mcad, and Gpr109A levels. In eWAT of old rats, only 0.1FF increased Pgc1α and Mcad expression. In both age groups median cell area of eWAT adipocytes was reduced after 0.5% FF. In sWAT Ucp1 gene expression was very low and UCP1 protein was undetectable. FF upregulated Ucp1, Cited1, Eva1, and Cpt1b expression in sWAT of young rats, with diminished effects in old rats. In both age groups 0.5% FF increased Fgf21 expression in sWAT. Median cell area of sWAT adipocytes decreased only in young rats treated with 0.5% FF. Our results reveal that fenofibrate differentially affects gene expression in BAT, with diminished effects in old compared to young rats. In WAT of young rats FF modestly stimulates the expression of factors/enzymes involved in lipid oxidative metabolism and browning. Aging reduces both these effects. Gpr109A may present a novel gene target upregulated by FF in BAT and eWAT.

Influence of chrysin on D-galactose induced-aging in mice: Up regulation of AMP kinase/liver kinase B1/peroxisome proliferator-activated receptor-γ coactivator 1-α signaling pathway.

Adenosine monophosphate kinase/liver kinase B1/peroxisome proliferator-activated receptor-γ coactivator 1-α (AMPK/LKB1/PGC1α) pathway has a vital role in regulating age-related diseases. It controls neurogenesis, cell proliferation, axon outgrowth, and cellular energy homeostasis. AMPK pathway also regulates mitochondrial synthesis. The current study evaluated the effect of chrysin on D-galactose (D-gal) induced-aging, neuron degeneration, mitochondrial dysfunction, oxidative stress, and neuroinflammation in mice. The mice were allocated randomly into four groups (10 each group): Group 1: normal control group, Group 2: D-gal group, Groups 3 and 4: chrysin (125 and 250 mg/kg, respectively). Groups 2-4 were injected with D-gal (200 mg/kg/day; s.c) for 8 weeks to induce aging. Groups 3 and 4 were orally gavaged every day concurrent with D-gal. At the end of experiment, behavioral, brain biochemical and histopathological changes were monitored. Chrysin administration elevated discrimination ratio in object recognition, Y Maze percentage alternation, locomotor activity and brain contents of AMPK, LKB1, PGC1α, NAD (P)H quinone oxidoreductase 1 (NQO1), heme oxygenase 1 (HO-1), nerve growth factor (NGF) (neurotrophin-3; NT-3), and seretonin as well as reduced brain contents of tumor necrosis factor-alpha (TNF-α), nuclear factor kappa B (NF-κB), advanced glycation end products (AGEs) and glial fibrillary acidic protein (GFAP) compared to D-gal-treated mice. Chrysin also alleviated cerebral cortex and white matter neurons degeneration. Chrysin protects against neurodegeneration, improves mitochondrial autophagy and biogenesis as well as activates antioxidant genes expression. In addition, chrysin ameliorates neuroinflammation and stimulates the release of NGF and serotonin neurotransmitter. So, chrysin has a neuroprotective effect in D-gal induced-aging in mice.

Swimming in cold water upregulates genes involved in thermogenesis and the browning of white adipose tissues.

The purpose of this study was to investigate whether there is an interacting effect of six weeks of swimming in cold water on the gene expression of browning markers in adipose tissue in rodents. Twenty male Wistar rats were randomly divided into four groups: Control (C, 25 °C), Cold Exposure (CE, 4 °C), Swimming in tepid Water (STW, 30 °C), and Swimming in Cold Water (SCW, 15 °C). The swimming included 2-3 min intervals, 1 min rest, until exhaustion, three days a week for six weeks, with 3 to 6% of bodyweight overload. Rats from CE were exposed to cold for 2 h per day, five days per week. After the experimental protocol, interscapular brown (BAT) and inguinal subcutaneous white (WAT) fat tissues were excised, weighed, and processed for beiging and mitochondrial biogenesis markers gene expression. The experimental protocols resulted in an apparent increase in the number of brown adipocytes (per mm2) in the adipose deposits compared to the C group; substantial changes were observed in the SCW group. Compared to other groups, cold exposure alone increased significantly serum norepinephrine, and also ß2-adrenergic receptor expression was upregulated in the adipocytes compared to the C group. The STW group increased the expression of peroxisome proliferator-activated receptor-γ (PPAR-γ) coactivator-1 alpha (PGC-1α), ß2-adrenergic receptor, and CCAAT/enhancer-binding proteins-α(c/EBP-α) in WAT in comparison with the C group(p < 0.05). In both adipocytes, the SCW intervention significantly upregulated the expression of PGC-1α, PPAR-γ, and c/EBP-α genes in comparison with the C and CE groups. In addition, the expression of TFAM and UCP1 was upregulated substantially in the SCW group compared to other groups. Our data demonstrate that swim training and cold exposure present additive effects in the expression of genes involved in the beiging process and mitochondrial biogenesis markers in BAT and WAT. In addition, it seems that the upregulation of these genes is related to the activation of ß2-adrenergic receptors.

UBIAD1 effectively alleviated myocardial ischemia reperfusion injury by activating SIRT1/PGC1α.

BACKGROUND AND OBJECTIVES: Myocardial ischemia-reperfusion injury (MIRI) threatens global health and lowers people's sense of happiness. Till now, the mechanism of MIRI has not been well-understood. Therefore, this study was designed to explore the role of UBIAD1 in MIRI as well as its detailed reaction mechanism. METHODS: The mRNA and protein expressions of UBIAD1 before or after transfection were measured using RT-qPCR and western blot. Western blot was also adopted to measure the expressions of signaling pathway-, mitochondrial damage- and apoptosis-related proteins. Moreover, mitochondrial membrane potential and ATP level were verified by JC-1 immunofluorescence and ATP kits, respectively. With the application of CCK-8, LDH and CK-MB assays, the cell viability, LDH and CK-MB levels were evaluated, respectively. In addition, the cell apoptosis was detected using TUNEL. Finally, the expressions of ROS, SOD, MDA and CAT were measured using DCFH-DA, SOD, MDA and CAT assays, respectively. RESULTS: In the present study, we found that UBIAD1 was downregulated in hypoxia-reoxygenation (H/R) -induced H9C2 cells and its upregulation could activate SIRT1/PGC1α signaling pathway. It was also found that UBIAD1 regulated mitochondrial membrane potential and ATP level via activating SIRT1/PGC1α signaling pathway. In addition, the injury of H/R-induced H9C2 cells could be relieved by UBIAD1 through the activation of SIRT1/PGC1α signaling pathway. Moreover, UBIAD1 exhibited inhibitory effects on apoptosis and oxidative stress of H/R-induced H9C2 cells through activating SIRT1/PGC1α signaling pathway. CONCLUSION: To sum up, UBIAD1 could alleviate apoptosis, oxidative stress and H9C2 cell injury by activating SIRT1/PGC1α, which laid experimental foundation for the clinical treatment of MIRI.

Effects of long-term resveratrol treatment in hypothalamic astrocyte cultures from aged rats.

Aging is intrinsically related to metabolic changes and characterized by the accumulation of oxidative and inflammatory damage, as well as alterations in gene expression and activity of several signaling pathways, which in turn impact on homeostatic responses of the body. Hypothalamus is a brain region most related to these responses, and increasing evidence has highlighted a critical role of astrocytes in hypothalamic homeostatic functions, particularly during aging process. The purpose of this study was to investigate the in vitro effects of a chronic treatment with resveratrol (1 µM during 15 days, which was replaced once every 3 days), a recognized anti-inflammatory and antioxidant molecule, in primary hypothalamic astrocyte cultures obtained from aged rats (24 months old). We observed that aging process changes metabolic, oxidative, inflammatory, and senescence parameters, as well as glial markers, while long-term resveratrol treatment prevented these effects. In addition, resveratrol upregulated key signaling pathways associated with cellular homeostasis, including adenosine receptors, nuclear factor erythroid-derived 2-like 2 (Nrf2), heme oxygenase 1 (HO-1), sirtuin 1 (SIRT1), proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), and phosphoinositide 3-kinase (PI3K). Our data corroborate the glioprotective effect of resveratrol in aged hypothalamic astrocytes, reinforcing the beneficial role of resveratrol in the aging process.

Effect of caffeine on mitochondrial biogenesis in the skeletal muscle - A narrative review.

Caffeine is one of the most widely used substances as recreational drug for performance-enhancement in sport, underpinned by a strong evidence base. Although the effects of caffeine are widely investigated within the scope of performance physiology, the molecular effects of caffeine within skeletal muscle remain unclear. Evidence from in vitro and in vivo models suggest that caffeine regulates the glucose metabolism in the skeletal muscle. Moreover, caffeine seems to stimulate CaMKII, PPARδ/ß, AMPK and PGC1α, classical markers of exercise-adaptations, including mitochondrial biogenesis and mitochondrial content. This review summarizes evidence to suggest caffeine-effects within skeletal muscle fibers, focusing on the putative role of caffeine on mitochondrial biogenesis to explore whether caffeine supplementation might be a strategy to enhance mitochondrial biogenesis.

Isolongifolene alleviates liver ischemia/reperfusion injury by regulating AMPK-PGC1α signaling pathway-mediated inflammation, apoptosis, and oxidative stress.

Isolongifolene (ISO) has antioxidant, anti-inflammatory, anticancer, and neuroprotective effects; however, it is unclear whether ISO has a protective effects against liver ischemia/reperfusion (I/R) injury. In this study, a mouse liver I/R injury model and a mouse AML12 cell Hypoxia reoxygenation (H/R) model were established after pretreatment with different concentrations of ISO. Serum transaminase levels, necrotic liver area, cell viability, inflammation response, oxidative stress, and apoptosis were used to evaluate the effect of ISO on liver I/R or cell H/R injury. Western blotting was used to detect Bax, Bcl-2, C-Caspase3, AMPK, P-AMPK, and PGC1α protein expression levels. The AMPK inhibitor, compound C, was used to inhibit the AMPK expression. The results showed that ISO reduced serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, liver necrosis, inflammatory factors IL-1ß, IL-6, MCP-1, and TNF-α expression, MPO+ inflammatory cell infiltration, MDA content, TUNEL-positive cell number, cell apoptosis rate, and the expression of pro-apoptotic proteins Bax and C-Caspase3, while increasing cell viability, SOD and GSH activity, and the expression of anti-apoptotic protein Bcl-2. Moreover, Western blotting results showed that ISO could increase the protein expression of P-AMPK and PGC1α. Following the addition of compound C, the protective effect of ISO was significantly weakened. Therefore, our results suggest that ISO alleviates liver I/R injury by regulating AMPK-PGC1α signaling pathway-mediated anti-inflammatory, and antioxidant and anti-apoptotic effects.

Saponins from Panax japonicus alleviate adipose tissue fibrosis and metabolic dysfunction in high-fat-diet-induced obese mice.

INTRODUCTION: Adipose tissue fibrosis is a typical feature of adipose tissue dysfunction in obese individuals, which is closely related to metabolic diseases. OBJECTIVE: To explore the effect and mechanism of Saponins from Panax japonicus (SPJ) on adipose tissue fibrosis in obese mice induced by high fat diet (HFD). MATERIALS AND METHODS: We established a HFD induced obese mice model. Then the obese mice were treated with 90 mg/kg SPJ by oral gavage for 10 weeks. The levels of adipose tissue fibrosis and molecules related to signalling pathways were measured. Then the effects of SPJ on TGFß1-induced fibrosis in 3T3-L1 differentiated adipocytes were evaluated. RESULTS: SPJ reduced body weight, fat accumulation, and improved glucose and lipid metabolism in obese mice. SPJ decreased collagen deposition and expressions of fibrotic genes in epididymal white adipose tissue (eWAT) of obese mice. SPJ decreased the levels of TGFß1 protein and pSmad2, and increased the expression of PPARγ and PGC1α, thus alleviating oxidative stress in eWAT. Consistently, SPJ inhibited TGFß1-induced fibrosis in 3T3-L1 differentiated adipocytes. CONCLUSIONS: SPJ may alleviate adipose tissue fibrosis and improve obesity by inhibiting TGFß1/Smad2 and activating PPARγ/PGC1α pathway. SPJ is expected to become an efficient medicine for treatment of obesity.

Chronic nitrate administration increases the expression the genes involved in the browning of white adipose tissue in female rats.

Nitrate, a nitric oxide (NO) donor, has antiobesity effect in female rats. This study hypothesized that the antiobesity effect of nitrate in female rats is due to the browning of white adipose tissue (WAT). Female Wistar rats (aged 8 months) were divided into two groups (n = 10/group): the control group received tap water and the nitrate group received water containing 100 mg/L of sodium nitrate for 9 months. At months 0, 3, 6, and 9, obesity indices were measured. At month 9, gonadal adipose tissue was used to measure messenger RNA (mRNA) and protein levels of peroxisome proliferator-activated receptor-γ (PPAR-γ), PPAR-γ coactivator 1-α (PGC1-α), uncoupling protein 1 (UCP1), and adipocyte density and area. After the 9-month intervention, nitrate-treated rats had lower body weight, body mass index, thoracic circumference, and abdominal circumference by 6.4% (p = .012), 9.1% (p = .029), 6.0% (p = .056), and 5.7% (p = .098), respectively. In addition, nitrate-treated rats had higher PPAR-γ (mRNA: 1.78-fold, p = .016 and protein: 19%, p = .076), PGC1-α (mRNA: 1.69-fold, p = .012 and protein: 68%, p = .001), and UCP1 (mRNA: 2.50-fold, p = .001 and protein: 81%, p = .001) in gonadal adipose tissue. Nitrate also reduced adipocyte area by 35% (p = .054) and increased adipocyte density by 31% (p = .086). In conclusion, antiobesity effect of nitrate in female rats is associated with increased browning of gonadal adipose tissue as indicated by higher expression of PPAR-γ, PGC1-α, and UCP1 and reduced adipocyte area and increased adipocyte density.

Calcitriol potentially alters HeLa cell viability via inhibition of autophagy.

Objective: This study was conducted to evaluate the effect of Calcitriol on cellular death in HeLa cells via autophagy and turn over due to mitochondria homeostasis. Methods: HeLa cell lines were grown in 24-well plates and treated with Calcitriol at varying doses (0.013 µM-0.325 µM) for varying time periods (2, 6, 12, and 18 h). Cell proteins were extracted with scrapers and lysed using RIPA buffer. Western blots were performed for proteins involved with autophagy (Lc3, p62), signaling (mTOR, PI3K, HIF1α), mitochondria (PGC1α, COX4, and Tom 20), and apoptosis (Caspase 3, Caspase 9, and PARP). Protein carbonyl levels were determined by measuring the indirect ROS level. An inhibition study using L-mimosine was performed to analyze the significance of HIF1α. Results: Calcitriol treatment induced cytotoxicity in a dose- and time-dependent manner and caused growth arrest in HeLa cells. The PI3K-AKT-mTOR pathway was activated, leading to inhibition of autophagy and alterations in mitochondria biogenesis homeostasis. Treatment with Calcitriol produced protein carbonyl levels similar to those in the cisplatin-treated and control groups. Increased ROS levels may cause toxicity and induce cell death specifically in cancer cells but not in normal cells. The inhibition of HIF1α partially rescued the HeLa cells from the toxic effects of Calcitriol treatment. Conclusion: We suggest that Calcitriol may shut down mitochondrial homeostasis in HeLa cells by inducing the PI3K-AKT-mTOR pathway and inhibiting autophagy, which leads to cell death.

PGC1α overexpression preserves muscle mass and function in cisplatin-induced cachexia.

BACKGROUND: Chemotherapy induces a cachectic-like phenotype, accompanied by skeletal muscle wasting, weakness and mitochondrial dysfunction. Peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC1α), a regulator of mitochondrial biogenesis, is often reduced in cachectic skeletal muscle. Overexpression of PGC1α has yielded mixed beneficial results in cancer cachexia, yet investigations using such approach in a chemotherapy setting are limited. Utilizing transgenic mice, we assessed whether overexpression of PGC1α could combat the skeletal muscle consequences of cisplatin. METHODS: Young (2 month) and old (18 month) wild-type (WT) and PGC1α transgenic male and female mice (Tg) were injected with cisplatin (C; 2.5 mg/kg) for 2 weeks, while control animals received saline (n = 5-9/group). Animals were assessed for muscle mass and force, motor unit connectivity, and expression of mitochondrial proteins. RESULTS: Young WT + C mice displayed reduced gastrocnemius mass (male: -16%, P < 0.0001; female: -11%, P < 0.001), muscle force (-6%, P < 0.05, both sexes), and motor unit number estimation (MUNE; male: -53%, P < 0.01; female: -51%, P < 0.01). Old WT + C male and female mice exhibited gastrocnemius wasting (male: -22%, P < 0.05; female: -27%, P < 0.05), muscle weakness (male: -20%, P < 0.0001; female: -17%, P < 0.01), and loss of MUNE (male: -82%, P < 0.01; female: -62%, P < 0.05), suggesting exacerbated cachexia compared with younger animals. Overexpression of PGC1α had mild protective effects on muscle mass in young Tg + C male only (gastrocnemius: +10%, P < 0.05); however, force and MUNE were unchanged in both young Tg + C male and female, suggesting preservation of neuromuscular function. In older male, protective effects associated with PGC1α overexpression were heighted with Tg + C demonstrating preserved muscle mass (gastrocnemius: +34%, P < 0.001), muscle force (+13%, P < 0.01), and MUNE (+3-fold, P < 0.05). Similarly, old female Tg + C did not exhibit muscle wasting or reductions in MUNE, and had preserved muscle force (+11%, P < 0.05) compared with female WT + C. Follow-up molecular analysis demonstrated that aged WT animals were more susceptible to cisplatin-induced loss of mitochondrial proteins, including PGC1α, OPA1, cytochrome-C, and Cox IV. CONCLUSIONS: In our study, the negative effects of cisplatin were heighted in aged animals, whereas overexpression of PGC1α was sufficient to combat the neuromuscular dysfunction caused by cisplatin, especially in older animals. Hence, our observations indicate that aged animals may be more susceptible to develop chemotherapy side toxicities and that mitochondria-targeted strategies may serve as a tool to prevent chemotherapy-induced muscle wasting and weakness.

Sirtuin 1 alleviates microglia-induced inflammation by modulating the PGC-1α/Nrf2 pathway after traumatic brain injury in male rats.

Microglial activation and the subsequent inflammatory response play important roles in the central nervous system after traumatic brain injury (TBI). Activation of the PGC-1α pathway is responsible for microglial activation after TBI. Our previous study demonstrated that SIRT1 alleviates neuroinflammation-induced apoptosis after TBI, and activation of the PGC-1α/Nrf2 pathway extenuates TBI-induced neuronal apoptosis. However, no study has investigated whether SIRT1 can affect the PGC-1α/Nrf2 pathway to induce microglial excitation and the subsequent neuroinflammatory response. Microglial activation and the levels of pro-inflammatory factors, namely, tumor necrosis factor (TNF-α), interleukin-1ß (IL-1ß), and interleukin-6 (IL-6) were assessed to evaluate the neuroinflammatory response after TBI. To examine the effects of SIRT1, immunohistochemical staining and western blot analysis were used to observe the nuclear translocation and secretion of PGC-1α, as well as the activation of the PGC-1α/Nrf2 pathway. Treatment with the SIRT1 inhibitor sirtinol promoted microglial activation and pro-inflammatory factor expression (TNF-α, IL-6, and IL-1ß) and inhibited PGC-1α and Nrf2 nuclear translocation and secretion after TBI, while treatment with the SIRT1 activator A3 had the opposite effects. The results of this study suggest that microglial activation, the subsequent neuroinflammatory response, and the PGC-1α/Nrf2 pathway play essential roles in secondary injury after TBI. These results indicate that SIRT1 protects neurons after TBI by inhibiting microglial activation and the subsequent inflammatory response, possibly by activating the PGC-1α/Nrf2 pathway.

Peroxisome Proliferator-activated Receptor Gamma Coactivator-1 Alpha: A Double-edged Sword in Prostate Cancer.

Peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC- 1α/PPARGC1A) is a pivotal transcriptional coactivator involved in the regulation of mitochondrial metabolism, including biogenesis and oxidative metabolism. PGC-1α is finely regulated by AMPactivated protein kinases (AMPKs), the role of which in tumors remains controversial to date. In recent years, a growing amount of research on PGC-1α and tumor metabolism has emphasized its importance in a variety of tumors, including prostate cancer (PCA). Compelling evidence has shown that PGC-1α may play dual roles in promoting and inhibiting tumor development under certain conditions. Therefore, a better understanding of the critical role of PGC-1α in PCA pathogenesis will provide new insights into targeting PGC-1α for the treatment of this disease. In this review, we highlight the procancer and anticancer effects of PGC-1α in PCA and aim to provide a theoretical basis for targeting AMPK/PGC-1α to inhibit the development of PCA. In addition, our recent findings provide a candidate drug target and theoretical basis for targeting PGC-1α to regulate lipid metabolism in PCA.

DHA alleviates diet-induced skeletal muscle fiber remodeling via FTO/m6A/DDIT4/PGC1α signaling.

BACKGROUND: Obesity leads to a decline in the exercise capacity of skeletal muscle, thereby reducing mobility and promoting obesity-associated health risks. Dietary intervention has been shown to be an important measure to regulate skeletal muscle function, and previous studies have demonstrated the beneficial effects of docosahexaenoic acid (DHA; 22:6 ω-3) on skeletal muscle function. At the molecular level, DHA and its metabolites were shown to be extensively involved in regulating epigenetic modifications, including DNA methylation, histone modifications, and small non-coding microRNAs. However, whether and how epigenetic modification of mRNA such as N6-methyladenosine (m6A) mediates DHA regulation of skeletal muscle function remains unknown. Here, we analyze the regulatory effect of DHA on skeletal muscle function and explore the involvement of m6A mRNA modifications in mediating such regulation. RESULTS: DHA supplement prevented HFD-induced decline in exercise capacity and conversion of muscle fiber types from slow to fast in mice. DHA-treated myoblasts display increased mitochondrial biogenesis, while slow muscle fiber formation was promoted through DHA-induced expression of PGC1α. Further analysis of the associated molecular mechanism revealed that DHA enhanced expression of the fat mass and obesity-associated gene (FTO), leading to reduced m6A levels of DNA damage-induced transcript 4 (Ddit4). Ddit4 mRNA with lower m6A marks could not be recognized and bound by the cytoplasmic m6A reader YTH domain family 2 (YTHDF2), thereby blocking the decay of Ddit4 mRNA. Accumulated Ddit4 mRNA levels accelerated its protein translation, and the consequential increased DDIT4 protein abundance promoted the expression of PGC1α, which finally elevated mitochondria biogenesis and slow muscle fiber formation. CONCLUSIONS: DHA promotes mitochondrial biogenesis and skeletal muscle fiber remodeling via FTO/m6A/DDIT4/PGC1α signaling, protecting against obesity-induced decline in skeletal muscle function.

Carnitine, apelin and resveratrol regulate mitochondrial quality control (QC) related proteins and ameliorate acute kidney injury: role of hydrogen peroxide.

Mitochondrial impairment is recognised as a prominent feature in kidney diseases. Therefore, we investigated whether the effects of resveratrol, L-carnitine, and apelin in the acute kidney injury model were associated with modulation of mitochondrial quality control (QC) related proteins, intra-renal renin-angiotensin (RAS) activity, adenosine triphosphate (ATP) and Na+-K+ ATPase gene expression. Rats were randomly assigned to 7 groups: Distilled water injected control group, DMSO injected control group, distilled water injected lipopolysaccharide (LPS) group, DMSO injected LPS group, resveratrol injected LPS group, L-carnitine injected LPS group and apelin 13 injected LPS group. We observed that resveratrol, L-carnitine, and apelin treatments altered mitochondrial (QC) related protein levels (Pink1, Parkin, BNIP-3, Drp1, and PGC1α), decreased intra-renal RAS parameters, increased ATP level and upregulated Na+-K+ ATPase gene expression in renal tissue. Our results provide new insight into the role of mitochondrial quality control and how different antioxidants exert beneficial effects on acute kidney injury.

Berberine Protects against Neurological Impairments and Blood-Brain Barrier Injury in Mouse Model of Intracerebral Hemorrhage.

BACKGROUND: Elevation of AMP-activated protein kinase (AMPK)/peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α) signaling can suppress intracerebral hemorrhage (ICH)-induced neurological impairments. As an isoquinoline alkaloid, Berberine exerts neuroprotective effects in neurological disease models with activated AMPK/PGC1α signaling. AIM: We aim to study the effect of Berberine on ICH-induced brain injury and explore the potential molecular mechanism. METHODS: ICH model was established in mice through intracerebral injection of autologous whole blood, followed by treatment with Berberine. Neurological impairments were assessed by the modified neurological severity score and behavioral assays. Brain edema and blood-brain barrier (BBB) integrity were assessed by water content in the brain, amount of extravasated Evans blue, and BBB tight junction components. Neuroinflammatory responses were assessed by inflammatory cytokine levels. AMPK/PGC1α signaling was examined by AMPK mRNA expression and phosphorylated AMPK and PGC1α protein levels. RESULTS: Berberine (200 mg/kg) attenuated ICH-induced neurological deficits, motor and cognitive impairment, and BBB disruption. Berberine also suppressed ICH-induced inflammatory responses indicated by reduced production of inflammatory cytokines. Finally, Berberine drastically elevated AMPK/PGC1α signaling in the hemisphere of ICH mice. CONCLUSION: Our findings suggest that Berberine plays an important neuroprotective role against ICH-induced neurological impairments and BBB injury, probably by inhibition of inflammation and activation of AMPK/PGC1α signaling.

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.

Peroxisome proliferator-activated receptor gamma coactivator-1α/HSF1 axis effectively alleviates lipopolysaccharide-induced acute lung injury via suppressing oxidative stress and inflammatory response.

Acute lung injury (ALI) interferes with lung function by causing pulmonary inflammation and oxidative stress. Suppressing intracellular reactive oxygen species (ROS) may block intracellular inflammation. Thus, the purpose of the current study was to investigate the roles of peroxisome proliferator-activated receptor gamma coactivator-1α (PGC1α)/HSF1 axis in an lipopolysaccharide (LPS)-induced ALI murine model and in RAW264.7 macrophages. In the LPS-administrated mouse model, the addition of PGC1α obviously ameliorated secretion of pro-inflammatory mediators tumor necrosis factor-α and Interleukin 6 as well as MCP-1 expression triggered by LPS stimulation, accompanied with reduced infiltration of inflammatory cells. Meanwhile, introduction of PGC1α strongly diminished the expression of cyclooxygenase-2 and inducible nitric oxide synthase as well as their products PGE2 and NO. In addition, administering PGC1α also dramatically alleviated LPS-triggered oxidative stress, as reflected by a reduction of ROS production, and also reduced malondialdehyde and O 2 content, concomitant with enhancement of superoxide dismutase, catalase, and glutathione peroxidase. Similarly, PGC1α effectively ameliorated LPS-induced inflammation response and oxidative stress, as exemplified by reduced pro-inflammatory cytokines and ROS production in LPS-induced RAW264.7 macrophages. Interestingly, PGC1α modulated the expression of HSF1 and the transcriptional activity of X-linked inhibitor of apoptosis (XIAP)-associated factor 1, whereas silencing of HSF1 abolished these effects. More importantly, deletion of HSF1 impeded the anti-inflammatory and anti-oxidant effects of PGC1α in LPS-induced macrophages. Taken together, PGC1α/HSF1 axis have an anti-oxidant and anti-inflammatory effects, indicating that PGC1α/HSF1 may protect against LPS-induced ALI, and thus may be a promising therapy to treat ALI.

N­terminal truncated peroxisome proliferator­activated receptor­Î³ coactivator­1α alleviates phenylephrine­induced mitochondrial dysfunction and decreases lipid droplet accumulation in neonatal rat cardiomyocytes.

N­terminal truncated peroxisome proliferator­activated receptor­Î³ coactivator­1α (NT­PGC­1α) is an alternative splice variant of PGC­1α. NT­PGC­1α exhibits stronger anti­obesity effects in adipose tissue than PGC­1α; however, NT­PGC­1α has not yet been investigated in neonatal rat cardiomyocytes (NRCMs). The present study aimed to investigate the role of NT­PGC­1α in mitochondrial fatty acid metabolism and its possible regulatory mechanism in NRCMs. NRCMs were exposed to phenylephrine (PE) or angiotensin II (Ang II) to induce cardiac hypertrophy. Following this, NRCMs were infected with adenovirus expressing NT­PGC­1α, and adenosine 5'­triphsophate (ATP) levels, reactive oxygen species (ROS) generation and mitochondrial membrane potential were subsequently detected. In addition, western blotting, lipid droplet staining and oxygen consumption assays were performed to examine the function of NT­PGC­1α in fatty acid metabolism. NT­PGC­1α was demonstrated to be primarily expressed in the cytoplasm, which differed from full­length PGC­1α, which was predominantly expressed in the nucleus. NT­PGC­1α overexpression alleviated mitochondrial function impairment, including ATP generation, ROS production and mitochondrial membrane potential integrity. Furthermore, NT­PGC­1α overexpression alleviated the PE­induced suppression of fatty acid metabolism­associated protein expression, increased extracellular oxygen consumption and decreased lipid droplet accumulation in NRCMs. Taken together, the present study demonstrated that NT­PGC­1α alleviated PE­induced mitochondrial impairment and decreased lipid droplet accumulation in NRCMs, indicating that NT­PGC­1α may have ameliorated mitochondrial energy defects in NRCMs, and may be considered as a potential target for the treatment of heart failure.