Synergistic activation of AMPK by AdipoR1/2 agonist and inhibitor of EDPs-EBP interaction recover NAFLD through enhancing mitochondrial function in mice

Nonalcoholic fatty liver disease (NAFLD), especially nonalcoholic steatohepatitis (NASH), is a common hepatic manifestation of metabolic syndrome. However, there are no effective therapy to treat this devastating disease. Accumulating evidence suggests that the generation of elastin-derived peptides (EDPs) and the inhibition of adiponectin receptors (AdipoR)1/2 plays essential roles in hepatic lipid metabolism and liver fibrosis. We recently reported that the AdipoR1/2 dual agonist JT003 significantly degraded the extracellular matrix (ECM) and ameliorated liver fibrosis. However, the degradation of the ECM lead to the generation of EDPs, which could further alter liver homeostasis negatively. Thus, in this study, we successfully combined AdipoR1/2 agonist JT003 with V14, which acted as an inhibitor of EDPs-EBP interaction to overcome the defect of ECM degradation. We found that combination of JT003 and V14 possessed excellent synergistic benefits on ameliorating NASH and liver fibrosis than either alone since they compensate the shortage of each other. These effects are induced by the enhancement of the mitochondrial antioxidant capacity, mitophagy, and mitochondrial biogenesis via AMPK pathway. Furthermore, specific suppression of AMPK could block the effects of the combination of JT003 and V14 on reduced oxidative stress, increased mitophagy and mitochondrial biogenesis. These positive results suggested that this administration of combination of AdipoR1/2 dual agonist and inhibitor of EDPs-EBP interaction can be recommended alternatively for an effective and promising therapeutic strategy for the treatment of NAFLD and NASH related fibrosis.

Honokiol alleviated neurodegeneration by reducing oxidative stress and improving mitochondrial function in mutant SOD1 cellular and mouse models of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease affecting both upper and lower motor neurons (MNs) with large unmet medical needs. Multiple pathological mechanisms are considered to contribute to the progression of ALS, including neuronal oxidative stress and mitochondrial dysfunction. Honokiol (HNK) has been reported to exert therapeutic effects in several neurologic disease models including ischemia stroke, Alzheimer's disease and Parkinson's disease. Here we found that honokiol also exhibited protective effects in ALS disease models both in vitro and in vivo. Honokiol improved the viability of NSC-34 motor neuron-like cells that expressed the mutant G93A SOD1 proteins (SOD1-G93A cells for short). Mechanistical studies revealed that honokiol alleviated cellular oxidative stress by enhancing glutathione (GSH) synthesis and activating the nuclear factor erythroid 2-related factor 2 (NRF2)-antioxidant response element (ARE) pathway. Also, honokiol improved both mitochondrial function and morphology via fine-tuning mitochondrial dynamics in SOD1-G93A cells. Importantly, honokiol extended the lifespan of the SOD1-G93A transgenic mice and improved the motor function. The improvement of antioxidant capacity and mitochondrial function was further confirmed in the spinal cord and gastrocnemius muscle in mice. Overall, honokiol showed promising preclinical potential as a multiple target drug for ALS treatment.

Rutin Promotes Browning of 3T3-L1 Preadipocytes and Its Mechanism / 中国实验方剂学杂志

ObjectiveTo investigate the effect of rutin on the browning of 3T3-L1 preadipocytes and the mechanism. MethodCell counting kit-8 （CCK-8） assay was used to detect the effect of different concentration of rutin （3.125， 6.25， 12.5， 25， 50， 100， 200 μmol·L-1） on 3T3-L1 cell activity， and Western blot to examine the effect of rutin （12.5， 25， 50 μmol·L-1） on the expression of thermogenesis-associated proteins uncoupling protein 1 （UCP1）， PR domain containing 16 （PRDM16） and peroxisome proliferator-activated receptor γ coactivator-1α （PGC-1α） in adipocytes. After the optimal concentration of rutin was determined， the effect of rutin on lipid droplet formation in adipocytes was observed based on oil red O staining， and the expression of nuclear respiratory factor 1 （NRF1）， nuclear respiratory factor 2 （NRF2） and mitochondrial transcription factor A （TFAM）， which were the landmark proteins of mitochondrial biosynthesis， was detected by Western blot. ResultCompared with the blank group， 200 μmol·L-1 rutin inhibited 3T3-L1 cell activity （P<0.01）. Compared with the blank group， at the concentration of 12.5， 25， 50 μmol·L-1 rutin significantly promoted the expression of thermogenesis-associated proteins （UCP1， PRDM16， and PGC-1α） （P<0.01）， which was determined as the optimal concentration. Compared with the blank group， 50 μmol·L-1 rutin significantly increased the immunofluorescence intensity of mitochondrial UCP1 protein in 3T3-L1 cells （P<0.01） and the expression of the markers of mitochondrial biosynthesis （NRF1， NRF2， and TFAM） （P<0.01）. In addition， 50 μmol·L-1 rutin significantly inhibited lipid droplet formation of 3T3-L1 adipocytes （P<0.01）. ConclusionRutin inhibited lipid droplet deposition in 3T3-L1 adipocytes and increased the expression of thermogenesis-related proteins （UCP1， PRDM16， and PGC-1α） and markers of mitochondrial biosynthesis （NRF1， NRF2， and TFAM）， thereby inducing the browning of 3T3-L1 adipocytes. This lays a basis for the development of drugs that safely regulate the browning of white cells.

Pathologically Elevated-Cyclic Stretch Suppressed Vascular Smooth Muscle Cell Mitochondrial Biogenesis by Down-regulating PGC1α Expression / 医用生物力学

Objective To investigate the effect of pathologically elevated-cyclic stretch induced by hypertension on mitochondrial biogenesis of vascular smooth muscle cells (VSMCs), and the role of PGC1α in this process. Methods The Flexcell-5000T stretch loading system in vitro was applied to VSMCs with a frequency of 1. 25 Hz and an amplitude of 5% or 15% to simulate the mechanical environment under normal physiological or hypertensive pathological conditions respectively. Western blotting and qPCR were used to detect the expression of PGC1α, citrate synthase and mitochondrial DNA (mtDNA) copy number in VSMCs under normal physiological or hypertensive pathological conditions. VSMCs were treated with PGC1α specific activator ZLN005 to promote PGC1α expression or specific interfering fragment siRNA to inhibit PGC1α expression in order to detect the effect on citrate synthase and mtDNA copy number. Results Compared with 5% physiological cyclic stretch, 15% pathologically elevated-cyclic stretch significantly suppressed the expression of PGC1α, citrate synthase and mtDNA copy number in VSMCs. Compared with control group, the protein expression of PGC1α was significantly decreased and increased respectively. When VSMCs transfected with PGC1α siRNA or incubated PGC1α activator ZLN005, the expression of citrate synthase and mtDNA copy number were also significantly down regulated and up-regulated in VSMCs accordingly. Under physiological cyclic stretch conditions, the protein level of PGC1α was significantly down-regulated by PGC1α siRNA, which also significantly down-regulated citrate synthase expression and mtDNA copy number. The protein expression of PGC1α was significantly up-regulated by ZLN005, which also enhanced the expression of citrate synthase and mtDNA copy number. Conclusions The pathological cyclic stretch induced by hypertension significantly down-regulated the expression of citrate synthase and mtDNA copy number via suppressing the expression of PGC1α, resulting in mitochondrial dysfunction of VSMCs. PGC1α may be a potential therapeutic target molecule to alleviate the progression of hypertension.

Research progress on the role of chondrocyte mitochondrial homeostasis imbalance in the pathogenesis of osteoarthritis / 中国修复重建外科杂志

OBJECTIVE@#To summarize the role of chondrocyte mitochondrial homeostasis imbalance in the pathogenesis of osteoarthritis (OA) and analyze its application prospects.@*METHODS@#The recent literature at home and abroad was reviewed to summarize the mechanism of mitochondrial homeostasis imbalance, the relationship between mitochondrial homeostasis imbalance and the pathogenesis of OA, and the application prospect in the treatment of OA.@*RESULTS@#Recent studies have shown that mitochondrial homeostasis imbalance, which is caused by abnormal mitochondrial biogenesis, the imbalance of mitochondrial redox, the imbalance of mitochondrial dynamics, and damaged mitochondrial autophagy of chondrocytes, plays an important role in the pathogenesis of OA. Abnormal mitochondrial biogenesis can accelerate the catabolic reaction of OA chondrocytes and aggravate cartilage damage. The imbalance of mitochondrial redox can lead to the accumulation of reactive oxygen species (ROS), inhibit the synthesis of extracellular matrix, induce ferroptosis and eventually leads to cartilage degradation. The imbalance of mitochondrial dynamics can lead to mitochondrial DNA mutation, decreased adenosine triphosphate production, ROS accumulation, and accelerated apoptosis of chondrocytes. When mitochondrial autophagy is damaged, dysfunctional mitochondria cannot be cleared in time, leading to ROS accumulation, which leads to chondrocyte apoptosis. It has been found that substances such as puerarin, safflower yellow, and astaxanthin can inhibit the development of OA by regulating mitochondrial homeostasis, which proves the potential to be used in the treatment of OA.@*CONCLUSION@#The mitochondrial homeostasis imbalance in chondrocytes is one of the most important pathogeneses of OA, and further exploration of the mechanisms of mitochondrial homeostasis imbalance is of great significance for the prevention and treatment of OA.

Isoliquiritigenin alleviates energy metabolism imbalance in type 2 diabetic mice / 药学学报

Isoliquiritigenin (ISL) is a flavonoid compound isolated from licorice. It possesses excellent antioxidant and anti-diabetic activities. This study aims to investigate the molecular mechanism underlying the alleviatory effect of ISL on energy metabolism imbalance caused by type 2 diabetes mellitus (T2DM). 8-week-old male C57BL/6J mice were used in in vivo experiments. The high-fat-high-glucose diet combined with intraperitoneal injection of streptozotocin was applied to establish T2DM animal model. All animal experiments were performed in accordance with the Institutional Guidelines of Laboratory Animal Administration issued by the Committee of Ethics at Beijing University of Chinese Medicine. HepG2 cells were used in in vitro experiments. Enzyme-linked immunosorbent assay (ELISA) and real-time quantitative polymerase chain reaction (RT-qPCR) were used to examine the protein and mRNA levels of mitochondrial function-related targets. The levels of reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) in HepG2 cells were measured by the flow cytometry. Additionally, the molecular docking of ISL and key target proteins was analyzed. It was found that ISL significantly inhibited the activity of mitochondrial respiratory chain complex I and increased the protein levels of uncoupling protein 2 (UCP2) in the livers of mice and HepG2 cells. It also obviously decreased the ROS levels and increased the MMP levels in cultured HepG2 cells. In addition, ISL promoted mitochondrial biogenesis by activating proliferator-activated receptor gamma co-activator 1α (PGC-1α) and enhanced mitophagy by upregulating Parkin. It also improved mitochondrial fusion by increasing the mRNA and protein levels of mitofusin 2 (MFN2). In conclusion, ISL alleviates energy metabolism imbalance caused by T2DM through suppression of excessive mitochondrial oxidative phosphorylation and promotion of mitochondrial biogenesis, mitophagy, and fusion.

Hepatic mitochondria in diet-induced obese mice (stereology and molecular analysis) / Mitocondrias hepáticas en ratones obesos inducidos por la dieta (estereología y análisis molecular)

SUMMARY: The world population is going through an obesity epidemic that has severe consequences for the health system. This study focused on studying hepatic mitochondria in obese animals induced by a high-fat (HF) diet and used the model-based stereology in electron micrographs for the quantitative study. Besides, the gene expressions of molecular markers of mitochondrial biogenesis carnitine palmitoyltransferase 1a (Cpt 1α), mitochondrial transcription factor a (Tfam), uncoupling protein 3 (Ucp 3), and nuclear respiratory factor 1 (Nrf 1) were analyzed. The HF diet caused a weight gain of +1820 % comparing the control group (C) with the HF group (from 0.32±0.31 g to 5.5±0.39 g, P<0.001). The HF group showed fat droplets in the hepatocyte cytoplasm (steatosis) and less dense and large mitochondria in transmission electron microscopy. The mitochondria size (cross-section) did not show a significant difference between the groups C and HF. However, the mitochondria numerical density per area was 30 % less, the mitochondrial surface density (outer membrane) was 20 % less, and the mitochondrial volume density was 22 % less in the HF group than the C group. The gene expressions of molecular markers of mitochondrial biogenesis Cpt 1α, Tfam, Ucp 3, and Nrf 1 decreased in the HF group compared to the C group. The quantitative results match perfectly with the molecular ones of mitochondrial biogenesis markers. In the future, it will be crucial to verify if and how these data recover with the reduction of obesity, which would be of significant interest given the current obesity epidemic that affects the world population.

RESUMEN: La población mundial atraviesa una epidemia de obesidad que tiene graves consecuencias para el sistema de salud. Este estudio se centró en el análisis de las mitocondrias hepáticas en animales obesos inducidos por una dieta alta en grasas (HF) y utilizó la estereología basada en modelos en micrografías electrónicas para el estudio cuantitativo. Además, se analizaron las expresiones génicas de los marcadores moleculares de la biogénesis mitocondrial carnitina palmitoiltransferasa 1a (Cpt 1α), factor de transcripción mitocondrial a (Tfam), proteína desacoplante 3 (Ucp 3) y factor respiratorio nuclear 1 (Nrf 1). La dieta HF provocó un aumento de peso de +1820 % comparando el grupo de control (C) con el grupo HF (de 0,32 ± 0,31 g a 5,5 ± 0,39 g, P <0,001). El grupo HF mostró gotas de grasa en el citoplasma de los hepatocitos (esteatosis) y mitocondrias menos densas y grandes en la microscopía electrónica de transmisión. El tamaño de las mitocondrias (sección transversal) no mostró una diferencia significativa entre los grupos C y HF. Sin embargo, la densidad numérica de mitocondrias por área fue 30% menor, la densidad de superficie mitocondrial (membrana externa) fue 20 % menor y la densidad de volumen mitocondrial fue 22 % menor en el grupo HF que en el grupo C. Las expresiones génicas de los marcadores moleculares de la biogénesis mitocondrial Cpt 1α, Tfam, Ucp 3 y Nrf 1 disminuyeron en el grupo HF en comparación con el grupo C. Los resultados cuantitativos coinciden perfectamente con los moleculares de los marcadores de biogénesis mitocondrial. En el futuro, será crucial verificar si estos datos se recuperan y cómo se recuperan con la reducción de la obesidad, lo que sería de gran interés dada la actual epidemia de obesidad que afecta a la población mundial.

A novel supplement with yeast β-glucan, prebiotic, minerals and Silybum marianum synergistically modulates metabolic and inflammatory pathways and improves steatosis in obese mice / 中西医结合学报

OBJECTIVE@#To evaluate the synergic effects of a novel oral supplement formulation, containing prebiotics, yeast β-glucans, minerals and silymarin (Silybum marianum), on lipid and glycidic metabolism, inflammatory and mitochondrial proteins of the liver, in control and high-fat diet-induced obese mice.@*METHODS@#After an acclimation period, 32 male C57BL/6 mice were divided into the following groups: nonfat diet (NFD) vehicle, NFD supplemented, high-fat diet (HFD) vehicle and HFD supplemented. The vehicle and experimental formulation were administered orally by gavage once a day during the last four weeks of the diet (28 consecutive days). We then evaluated energy homeostasis, inflammation, and mitochondrial protein expression in these groups of mice.@*RESULTS@#After four weeks of supplementation, study groups experienced reduced glycemia, dyslipidemia, fat, and hepatic fibrosis levels. Additionally, proliferator-activated receptor-α, AMP-activated protein kinase-1α, peroxisome proliferator-activated receptor γ co-activator-1α, and mitochondrial transcription factor A expression levels were augmented; however, levels of inhibitor of nuclear factor-κB kinase subunit α and p65 nuclear factor-κB expression, and oxidative markers were reduced. Notably, the cortisol/C-reactive protein ratio, a well-characterized marker of the hypothalamic-pituitary-adrenal axis immune interface status, was found to be modulated by the supplement.@*CONCLUSION@#We discovered that the novel supplement was able to modify different antioxidant, metabolic and inflammatory pathways, improving the energy homeostasis and inflammatory status, and consequently alleviated hepatic steatosis.

Syringic acid improves oxidative stress and mitochondrial biogenesis in the liver of streptozotocin-induced diabetic rats

Objective: To determine the effects of syringic acid on hepatic damage in diabetic rats.Methods: Diabetes was induced by streptozotocin. Diabetic rats were given syringic acid at doses of 25, 50 and 100 mg/kg by oral gavage for 6 weeks. Syringic acid effects on the liver were evaluated by examination of plasma biochemical parameters, and pathological study. In addition, biomarkers of lipid peroxidation and antioxidant status of liver tissues were assessed. Real time-PCR was performed to investigate the mRNA expression levels of mitochondrial biogenesis indices in different groups. Results: Syringic acid significantly attenuated the increase in most of plasma biochemical parameters in diabetic rats. Moreover, syringic acid treatment increased the catalase activity while it reduced the superoxide dismutase activity and hepatic malondialdehyde level in diabetic rats. There was no difference between the glutathione content of the treated and untreated groups. These findings were supported by alleviation of histopathological damages in the syringic acid-treated groups compared to the untreated diabetic group. Syringic acid also significantly up-regulated the hepatic mRNA expression of PGC-1α, NRF-1, and NRF-2 and increased the mtDNA/nDNA ratio in diabetic rats. Conclusions: Syringic acid can be considered as a suitable candidate against hepatic complications since it can reduce oxidative damages in diabetic cases. Furthermore, it has the potential of targeting hepatic mitochondria in diabetes.

The effects of resveratrol on mitochondrial biogenesis dysfunction induced by fluoride in human neuroblastoma SH-SY5Y cells / 中华劳动卫生职业病杂志

Objective@#To explore the role of mitochondrial biogenesis and the neuroprotective mechanism of resveratrol in fluoride neurotoxicity.@*Methods@#SH-SY5Y cells in exponential phase were treated with different concentrations (20, 40, 60 mg/L) of sodium fluoride (NaF) for 24 h. Co-treatment with 60 mg/L NaF, 20 μmol/L resveratrol (RSV) was administrated in the resveratrol intervene trial. Western blotting was used to determine the expression levels of mitochondrial biogenesis key regulating factor of peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α) , nuclear respiratory factor 1 (NRF1) and mitochondrial transcription factor A (TFAM) in SH-SY5Y cells. The mRNA levels of PGC-1α, NRF1 and TFAM were determined by Quantitative Real-time PCR in SH-SY5Y cells, as well as the relative mitochondrial DNA (mtDNA) contents and mRNA expression of mitochondrial respiratory chain complexes subunit CO1 and ATP8. Flow cytometry was used to determine mitochondrial membrane potential in SH-SY5Y cells.@*Results@#Both the protein and mRNA levels of PGC-1α, NRF1 and TFAM were decresed after 60 mg/L NaF treatment in SH-SY5Y cells (P<0.05) . The relative mtDNA contents and mRNA expression of complexes subunit CO1 and ATP8 were also significantly decreased compared with control (P<0.05) . Mitochondrial membrane potential were also significantly decreased after 60 mg/L NaF treatment in SH-SY5Y cells (P<0.05) . Compared with 60 mg/L NaF group, the protein and mRNA levels of PGC-1α, NRF1 and TFAM in 20 μmol/L RSV+60 mg/L NaF group were significantly increased (P<0.05) . The relative mtDNA contents, mitochondrial membrane potential and mRNA levels of complexes subunit CO1 and ATP8 in 20 μmol/L RSV+60 mg/L NaF group were also significantly higher than that in 60 mg/L NaF group (P<0.05) .@*Conclusion@#Resveratrol may alleviate the fluoride-induced mitochondrial biogenesis dysfunction in SH-SY5Y cells.

Fibroblast growth factor receptor-1 is essential for regulation of mitochondrial biogenesis via control of microRNA let-7b / 中华内分泌代谢杂志

Objective To explore the role of fibroblast growth factor receptor ( FGFR ) 1 in endothelial homeostasis via an induction of microRNA let-7s, with effects on AcSDKP(N-acetyl-seryl-aspartyl-lysyl-proline) and associated mitochondrial biogenesis. Methods Blocking FGFR1 signaling pathway, Western blot and immunofluorescence staining were used to measure mitochondrial fusion ( mitofusin-2, MFN2;optic atrophy protein 1, OPA1 ) and fission ( dynamin-related protein-1, DRP1 ) proteins and mitochondrial biogenesis by MitoTraker Green. Also real-time quantitative PCR(qPCR) was performed to test microRNA let-7' expression. Results FGFR1 signaling pathway was critical for AcSDKP maintaining mitochondrial biogenesis through induction of microRNA let-7b. In endothelial cells, the AcSDKP restored the triple[TGF-β2, interleukin (IL)-1β, tumor necrosis factor (TNF)-α]-suppressed microRNA let-7b-5p expression and associated with mitochondrial biogenesis. Such effect of AcSDKP was lost in either fibroblast growth factor receptor substrate 2 (FRS2) siRNA or neutralizing FGFR1 treated-cells. Similarly, AcSDKP lost its effect on mitochondrial biogenesis in microRNA let-7b-5p inhibitor-treated-cells. In addition, microRNA let-7b-5p mimic reversed the FRS2 siRNA-suppressed mitochondrial biogenesis in endothelial cells. Conclusion These findings demonstrated that FGFR1 is critical for maintaining mitochondrial biogenesis through control of microRNA let-7b-5p in endothelial cells.

The influence of aerobic exercise on the structure, function and expression of energy metabolism-related molecules in skeletal muscle of aged rats / 中华老年医学杂志

Objective To examine the effects of aerobic exercise on muscle morphology,oxidation resistance,energy metabolism,mitochondrial biogenesis-related signal transduction pathway molecules,and energy metabolism-related enzyme proteins expression in aged rats and to explore the molecular mechanisms of skeletal muscle aging and aerobic exercise intervention.Methods Male Sprague Dawley rats were divided into a normal group,a model group,and an exercise group,with the latter two groups receiving a subcutaneous injection of 10％ D-galactose(0.1 mg · g-1 · d-1)for 10 weeks.Then aerobic and anaerobic exercise capacity of each group were tested by treadmill;the cross-sectional area of rats' gastrocnemius was examined via light microscopy;levels of serum superoxide dismutase(SOD) activity and malondialdehyde(MDA) were determined by spectrophotometry;serumβ Galase levels were tested by enzyme-linked immunosorbent assay (ELISA);levels of adenosine triphosphate (ATP),adenosine diphosphate (ADP) and adenosine monophosphate (AMP) in gastrocnemius tissue were measured by high performance liquid chromatography(HPLC) ultraviolet detection;expression levels of mitochondrial biosynthesis-related signal transduction molecules(such as p38MAPK,CaMK Ⅱ,PGC-1α,MEF2C,COXⅣ and ATPase) were tested by real-time RT-PCR.Results Compared with the normal group,the model group's cross-sectional area of muscle fibers,serum SOD activity,ATP content,and EC values all markedly decreased,while serum MDA,β Galase,AMP content in skeletal muscle significantly increased(all P ＜0.05).Levels of mRNA expression of CaMK Ⅱ,MEF2C,ATPascβ,COXIV,and PCG-1 alpha in model rats notably decreased(all P＜0.05),whereas mRNA expression levels of P38MAPK significantly increased(P＜0.05).Compared with the model group,aerobic exercise increased the cross-sectional area of muscle fibers(P＜0.01)and serum SOD activity (P ＜ 0.05),reduced serum MDA content (P ＜ 0.01),clearly increased CaMK Ⅱ and ATPaseβ％ mRNA expression(both P ＜ 0.01),and reduced the expression of P38MAPK mRNA (P ＜ 0.01).Conclusions Aerobic exercise can improve the activity of SOD,reduce the accumulation of oxygen free radicals,resist oxidation damage,correct the abnormal activity of P38MAPK,and promote the expression of mitochondrial biosynthesis-related signal molecules,such as CaMK Ⅱ,PCG-1 alpha,and MEF2C,thus boosting the expression and activity of energy metabolism enzyme protein COX Ⅳ,ATPase,promoting energy metabolism,improving the production of ATP,and slowing down the ageing process of the body and skeletal muscle.

Comparison of endoplasmic reticulum stress and mitochondrial biogenesis responses after 12 weeks of treadmill running and ladder climbing exercises in the cardiac muscle of middle-aged obese rats

The purpose of the present study was to compare the influence of aerobic exercise (AE) lasting 12 weeks to that of resistance exercise (RE) of the same duration on endoplasmic reticulum (ER) stress and mitochondrial biogenesis in the cardiac muscle of middle-aged obese rats. Obesity was induced in thirty 50-week-old male Sprague Dawley rats over 6 weeks by administration of a high-fat diet. The rats were then subjected to treadmill-running (AE) and ladder-climbing (RE) exercises 3 times per week for 12 weeks. Rats in the AE group showed significantly lower increases in body weight and intraperitoneal fat than those in the sedentary control (SC) group (P<0.05). The 12-week exercise regimes resulted in a significant increase in expression of mitochondrial biogenesis markers and levels of peroxisome proliferator-activated receptor gamma coactivator 1α in the cardiac muscle (P<0.05). Phosphorylation of PKR-like ER kinase, an ER stress marker, decreased significantly (P<0.05) after the exercise training. Although a trend for decreased C/EBP homologous protein (CHOP) expression was observed in both exercise groups, only the AE group had a statistically significant decrease (P<0.05). Levels of GRP78, an ER stress marker that protects cardiac muscle, did not significantly differ among the groups. Although only the AE group decreased body weight and fat mass, the two exercise regimes had similar effects on cardiac muscle with the exception of CHOP. Therefore, we suggest that both AE, which results in weight loss, and high-intensity RE, though not accompanied by weight loss, protect obese cardiac muscle effectively.

The effect of HMGB1 on mitochondrial biogenesis in anoxia environment / 医学研究生学报

Objective High mobility group box-1 protein ( HMGB1) plays an essential role in regulating energy metabolism of tumor cells via affecting mitochondrial autophagy .The aim of this study was to explore the effect of HMGB 1 on mitochondrial biogene-sis and cell energy metabolism in anoxia environment . Methods HepG2 cells were divided into normoxia control group ( cells were cultured in a culture box containing 5%CO2) , hypoxia control group ( cells were cultured in a culture box containing 1%O2+5%CO2+94%N2 ) , hypoxia HMGB1 siRNA group ( cells were cultured in a culture box containing 1% O2+5% CO2+94% N2 after transfected with HMGB1 siRNA) and hypoxia NC siRNA group ( cells were cultured in a culture box containing 1%O2+5%CO2+94%N2 after trans-fected with negative control siRNA ) .MTS assay was carried out to measure cell proliferation rate .The alterations of mitochondrial bio-genesis associated proteins were detected by RT-PCR and western blot.Mitochondrial density and morphology were determined by transmission electron microscopy (TEM).The ATP content in whole cell extracts was determined with a colorimetric ATP detection kit . Results Compared with the hypoxia control and hypoxia NC siR-NA group, the proliferationof hypoxia HMGB1 siRNA group was significantly inhibited, especially in 48 h and 72 h(P<0.05).Com-pared with hypoxia control group and hypoxia NC siRNA group , the expression of PGC 1α, NRF1and TFAM in hypoxia HMGB1 siRNA group were decreased significantly ( P<0.05) .Western blot results showed that , compared with normoxia control group , the expressions of PGC1α(0.494±0.210 vs 0.090±0.020), NRF1(1.080±0.470 vs 0.581±0.190)and TFAM(1.585±0.340 vs 0.792±0.350) protein in hypoxia 24 h group were increased obviously ( P<0.05) .Compared with hypoxia control group and hypoxia NC siRNA group , the expres-sions of PGC 1α, NRF1 and TFAM protein in hypoxia HMGB1 siRNA group were significantly decreased (P<0.05).Compared with hypoxia control group , the content of ATP in the HMGB 1 siRNA hypoxia group was significantly decreased , and hypoxia 12 h and 24 h were the most obvious ( P<0.05) . Conclusion HMGB1 could maintain cell energy metabolism by regulating mitochondrial biogene-sis so that cells could continue to proliferate in adverse anoxia environment .

Effects of dietary leucine supplementation on the hepatic mitochondrial biogenesis and energy metabolism in normal birth weight and intrauterine growth-retarded weanling piglets

BACKGROUND/OBJECTIVES: The study was conducted to evaluate the effects of dietary leucine supplementation on mitochondrial biogenesis and energy metabolism in the liver of normal birth weight (NBW) and intrauterine growth-retarded (IUGR) weanling piglets. MATERIALS/METHODS: A total of sixteen pairs of NBW and IUGR piglets from sixteen sows were selected according to their birth weight. At postnatal day 14, all piglets were weaned and fed either a control diet or a leucine-supplemented diet for 21 d. Thereafter, a 2 × 2 factorial experimental design was used. Each treatment consisted of eight replications with one piglet per replication. RESULTS: Compared with NBW piglets, IUGR piglets had a decreased (P < 0.05) hepatic adenosine triphosphate (ATP) content. Also, IUGR piglets exhibited reductions (P < 0.05) in the activities of hepatic mitochondrial pyruvate dehydrogenase (PDH), citrate synthase (CS), α-ketoglutarate dehydrogenase (α-KGDH), malate dehydrogenase (MDH), and complexes I and V, along with decreases (P < 0.05) in the concentration of mitochondrial DNA (mtDNA) and the protein expression of hepatic peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α). Dietary leucine supplementation increased (P < 0.05) the content of ATP, and the activities of CS, α-KGDH, MDH, and complex V in the liver of piglets. Furthermore, compared to those fed a control diet, piglets given a leucine-supplemented diet exhibited increases (P < 0.05) in the mtDNA content and in the mRNA expressions of sirtuin 1, PGC-1α, nuclear respiratory factor 1, mitochondrial transcription factor A, and ATP synthase, H+ transporting, mitochondrial F1 complex, β polypeptide in liver. CONCLUSIONS: Dietary leucine supplementation may exert beneficial effects on mitochondrial biogenesis and energy metabolism in NBW and IUGR weanling piglets.

Effects of intermittent ladder-climbing exercise training on mitochondrial biogenesis and endoplasmic reticulum stress of the cardiac muscle in obese middle-aged rats

The aim of this study is to investigate the effects of intermittent ladder-climbing exercise training on mitochondrial biogenesis and ER stress of the cardiac muscle in high fat diet-induced obese middle-aged rats. We induced obesity over 6 weeks of period in 40 male Sprague-Dawley rats around 50 weeks old, and were randomly divided into four experimental groups: chow, HFD, exercise+HFD, and exercise+chow. The exercising groups underwent high-intensity intermittent training using a ladder-climbing and weight exercise 3 days/week for a total of 8 weeks. High-fat diet and concurrent exercise resulted in no significant reduction in body weight but caused a significant reduction in visceral fat weight (p<0.05). Expression of PPARδ increased in the exercise groups and was significantly increased in the high-fat diet+exercise group (p<0.05). Among the ER stress-related proteins, the expression levels of p-PERK and CHOP, related to cardiac muscle damage, were significantly higher in the cardiac muscle of the high-fat diet group (p<0.05), and were significantly reduced by intermittent ladder-climbing exercise training (p<0.05). Specifically, this reduction was greater when the rats underwent exercise after switching back to the chow diet with a reduced caloric intake. Collectively, these results suggest that the combination of intermittent ladder-climbing exercise training and a reduced caloric intake can decrease the levels of ER stress-related proteins that contribute to cardiac muscle damage in obesity and aging. However, additional validation is required to understand the effects of these changes on mitochondrial biogenesis during exercise.

Ethanol Modulates Mitochondrial Production of AC16 Cardiomyocytes by Interfering with PGC-1αExpression / 中国医科大学学报

Objective To investigate the expression of peroxisome proliferator?activated receptorγcoactivator?1α(PGC?1α),nuclear respiratory factor 1(NRF?1),mitochondrial transcription factor A(TFAM)and mitochondrial structural and functional alterations under different concentra?tions of ethanol. Methods MTT assay was used to determine the survival rate of AC16 cells under different concentrations of ethanol,and the ap?propriate concentration of ethanol used for subsequent experiments was selected. Mitochondrial membrane potential of AC 16 cells was measured by flow cytometry using fluorescent probe JC?1. The ultrastructural changes of different groups of cells was observed under the electron microscope. The expressions of PGC?1αand its target proteins NRF?1 and TFAM were detected by real?time PCR and Western blotting. Results The number of mitochondrion,mitochondrial membrane potential,and the expressions of PGC?1α,NRF?1,and TFAM were increased in low?concentration eth?anol group(50 mmol/L). While in high?concentration ethanol group(200 mmol/L),they were all decreased,some mitochondria were larger than normal size;the cristae in some mitochondria were disordered,and some mitochondria had no cristae,appearing as circular or elongated vesicles. Conclusion The effect of ethanol on cardiovascular disease is mainly by regulating the expressions of PGC?1αand its downstream proteins NRF?1 and TFAM,which are the key factors in regulating mitochondrial biogenesis.

Research progress of mitochondrial biogenesis and cerebral ischemia/reperfusion injury / 中国病理生理杂志

Mitochondria are important intracellular energy supply organelles .As semi-autonomous organelles , the mitochondrial biogenesis , damage and clearance were the dynamic processes , which are dual-regulated by mitochondrial genes and nuclear genes , and maintain mitochondrial homeostasis according to the needs of the cells for energy .Recent studies provide evidence that the disorder of mitochondrial biogenesis in the neurons participates in the pathological process after cerebral ischemia/reperfusion, resulting in metabolic disturbance and cell apoptosis .This paper reviews the research progress of mitochondrion and cerebral ischemia/reperfusion injury .

The role of eNOS on the regulatory effects of EPO on mitochondrial biogenesis in cardiomyocytes exposed to chronic hypoxia / 重庆医学

Objective To explore the role of endothelial nitric oxide synthase(eNOS) in the regulatory effects of erythropoie‐tin (EPO) on mitochondiral biogenesis in cardiomyocytes exposed to chronic hypoxia .Methods H9c2 cardiomyocytes were cultured in the environment of hypoxia for 1 week(94% N2 ,5% O2 ) ,establishing the chronic hypoxic cardiomyocyte model .All the cells were divided into 3 groups :HC(chronic hypoxic control) ,HE[treated with chronic hypoxia and 20 U/mL recombinant human EPO (rhEPO) ]and HR(cells transfected with eNOS shRNA plasmid and treated with 20 U/mL rhEPO and chronic hypoxia) .Fluores‐cent probe was used to detect the changes of mitochondial number .Mitochondial DNA (mtDNA) relative express level was assayed by RT‐PCR .The expression and phosphorylation of eNOS protein were analyzed with Western blot .Results rhEPO significantly increased the phosphorylation of eNOS and elavated the mitochondialt number and mtDNA (P< 0 .05) .shRNA interference on eNOS significantly blocked all the above changes induced by rhEPO (P<0 .05) .Conclusion Phosphory lation of eNOS is the im‐portant signalling pathway for the enhanced mitochondrial biogenesis in cardiomyocytes exposed to chronic hypoxia by EPO .

Influence of caloric restriction and exercise on mitochondrial quality control in skeletal muscle / 体力科学

Mitochondria play a central role in energy production but also are the main cellular source of reactive oxygen species (ROS). It is widely believed that aging is related to the accumulation of oxidative molecular damage due to ROS. Aging also induces a decrease in muscle function. Recent studies indicate that caloric restriction and physical exercise suppress the decrease in muscle function though the maintaining quality of mitochondria. This review provides the current understanding of the influence of caloric restriction and exercise on mitochondrial quality control in skeletal muscle.