4-Hydroxycinnamic acid attenuates neuronal cell death by inducing expression of plasma membrane redox enzymes and improving mitochondrial functions

Many approaches to neurodegenerative diseases that focus on amyloid-βclearance and gene therapy have not been successful.Some therapeutic applications focus on enhancing neuronal cell survival during the pathogenesis of neurodegenerative diseases,including mitochondrial dysfunction.Plasma membrane(PM)redox enzymes are crucial in maintaining cellular physiology and redox homeostasis in response to mitochondrial dysfunction.Neurohormetic phytochemicals are known to induce the expression of detoxifying enzymes under stress conditions.In this study,mechanisms of neuroprotective effects of 4-hydroxycinnamic acid(HCA)were examined by analyzing cell survival,levels of abnormal proteins,and mitochondrial functions in two different neuronal cells.HCA protected two neuronal cells exhibited high expression of PM redox enzymes and the consequent increase in the NAD^(+)/NADH ratio.Cells cultured with HCA showed delayed apoptosis and decreased oxidative/nitrative damage accompanied by decreased ROS production in the mitochondria.HCA increased the mitochondrial complexes I and II activities and ATP production.Also,HCA increased mitochondrial fusion and decreased mitochondrial fission.Overall,HCA maintains redox homeostasis and energy metabolism under oxidative/metabolic stress conditions.These findings suggest that HCA could be a promising therapeutic approach for neurodegenerative diseases.

Effect of Mitochondrial Function of Ovarian Granulosa Cells on In Vitro Fertilization and Embryo Transfer Outcomes in Obese Polycystic Ovary Syndrome Patients

Objective:To investigate the effect of abnormal ovarian granulosa cell metabolism on in vitro fertilization and embryo transfer(IVF-ET)outcomes in obese polycystic ovary syndrome(PCOS)patients.Methods:Patients with PCOS who met the study criteria were screened according to the inclusion criteria.A total of 32 patients with obese PCOS were recruited into the study group,and 39 patients with non-obese PCOS were recruited into the control group.The general data(age,body mass index,and years of infertility),insulin resistance index(HOMA-IR),follicle-stimulating hormone(FSH),luteinizing hormone(LH),granulosa cell mitochondrial function,and IVF-ET outcome of patients in the study group and control group were retrospectively analyzed.Results:The differences in age and years of infertility between the study group and the control group were insignificant(P>0.05),and the body mass index(BMI)of the study group and control group was 30.5±1.24 kg/m2 and 22.3±1.12 kg/m2,respectively,in which the difference was statistically significant(P<0.05);the HOMA-IR of the study group was significantly higher than that of the control group(P<0.05);the reactive oxygen species(ROS)in the study group was significantly higher than that in the control group(P<0.05),and the ATP content in the study group was significantly lower than that in the control group(P<0.05);comparing the FSH and LH levels between the two groups,the difference was not statistically significant(P>0.05);the rate of IVF-ET failure was significantly higher in the study group than in the control group.Conclusion:PCOS is a complex endocrine disorder,and obesity is one of the independent risk factors for the development of PCOS.

Regulation of mitochondrial function and endoplasmic reticulum stress by nitric oxide in pluripotent stem cells

Mitochondrial dysfunction and endoplasmic reticulum stress(ERS) are global processes that are interrelated and regulated by several stress factors. Nitric oxide(NO) is a multifunctional biomolecule with many varieties of physiological and pathological functions, such as the regulation of cytochrome c inhibition and activation of the immune response, ERS and DNA damage; these actions are dose-dependent. It has been reported that in embryonic stem cells, NO has a dual role, controlling differentiation, survival and pluripotency, but the molecular mechanisms by which it modulates these functions are not yet known. Low levels of NO maintain pluripotency and induce mitochondrial biogenesis. It is well established that NO disrupts the mitochondrial respiratory chain and causes changes in mitochondrial Ca^(2+) flux that induce ERS. Thus, at high concentrations, NO becomes a potential differentiation agent due to the relationship between ERS and the unfolded protein response in many differentiated cell lines. Nevertheless, many studies have demonstratedthe need for physiological levels of NO for a proper ERS response. In this review, we stress the importance of the relationships between NO levels, ERS and mitochondrial dysfunction that control stem cell fate as a new approach to possible cell therapy strategies.

Effects of dietary tributyrin on intestinal mucosa development,mitochondrial function and AMPK-mTOR pathway in weaned pigs

Background:The objective of this experiment was to investigate the influence of dietary tributyrin on intestinal mucosa development,oxidative stress,mitochondrial function and AMPK-mTOR signaling pathway.Methods:Seventy-two pigs were divided into two treatments and received either a basal diet or the same diet supplemented with 750 mg/kg tributyrin.Each treatment has six replicates of six pigs.After 14 days,6 pigs from each treatment were selected and the jejunal samples were collected.Results:Results showed that supplemental tributyrin increased(P<0.05)villus height and villus height:crypt depth of weaned pigs.Pigs fed tributyrin had greater(P<0.05)RNA/DNA and protein/DNA ratios than pigs on the control group.The mRNA levels of sodium glucose transport protein-1 and glucose transporter-2 in the jejunum were upregulated(P<0.05)in pigs fed the tributyrin diet.Dietary tributyrin supplementation lowered(P<0.05)the malondialdehyde and hydrogen peroxide(H2O2)content in jejunum,enhanced(P<0.05)the mitochondrial function,as demonstrated by decreased(P<0.05)reactive oxygen species level and increased(P<0.05)mitochondrial membrane potential.Furthermore,tributyrin increased(P<0.05)mitochondrial DNA content and the mRNA abundance of genes related to mitochondrial functions,including peroxisomal proliferator-activated receptor-γcoactivator-1α,mitochondrial transcription factor A,nuclear respiratory factor-1 in the jejunum.Supplementation with tributyrin elevated(P<0.05)the phosphorylation level of AMPK and inhibited(P<0.05)the phosphorylation level of mTOR in jejunum compared with the control group.Conclusions:These findings suggest that dietary supplementation with tributyrin promotes intestinal mucosa growth,extenuates oxidative stress,improves mitochondrial function and modulates the AMPK-mTOR signal pathway of weaned pigs.

REAL-TIME MONITORING OF MITOCHONDRIAL FUNCTION AND CEREBRAL BLOOD FLOW FOLLOWING FOCAL ISCHEMIA IN RATS

Focal ischemia due to reduction of cerebral blood flow(CBF),creates 2 zones of damage:the core area,which suffers severe damage,and penumbra area,which surrounds the core and suffers intermediate levels of injury.Objectives:A novel method is introduced,which evaluates mitochondrial function in the core and in the penumbra,during focal cerebral ischemia.Methods:Wistar rats underwent focal cerebral ischemia by middle cerebral artery occlusion(MCAO)for 60 minutes,followed by 60 minutes of reperfusion.Mitochondrial function was assessed by a unique Multi-Site—Multi-Parametric(MSMP)monitoring system,which measures mitochondrial NADH using fluorometric technique,and CBF using Laser Doppler Flowmetry(LDF).Results:At the onset of occlusion,CBF dropped and NADH increased significantly only in the right hemisphere.CBF levels were significantly lower and NADH significantly higher in the core than in the penumbra.After reperfusion,CBF and NADH recovered correspondingly to the intensity of ischemia.Conclusion:Application of the MSMP system can add significant information for the understanding of the cerebral metabolic state under ischemic conditions,with an emphasis on mitochondrial function.

SLP-2: a potential new target for improving mitochondrial function in Parkinson's disease

Parkinson＇s disease （PD） is a progressive neurodegenerative disease, which is generally considered a multifactorial disorder that arises owing to a combination of genes and environmental factors. While most cases are idiopathic, in about 10% of the patients a genetic cause can be detected, ascribable to mutations in more than a dozen genes. PD is characterized clinically by tremor, rigidity, reduced mo- tor activity （bradykinesia）, and postural instability and pathological- ly by loss of dopaminergic （DA） neurons in the substantia nigra pars compacta, loss of DA innervation in the striatum, and the presence of a-synuclein positive aggregates in the form of Lewy bodies. The symptomatic treatment of PD with levodopa, which aims at replac- ing dopamine, remains the gold standard, and no neuroprotective or disease-modifying therapy is available. During treatment, the disease continues to progress, and long-term use of levodopa has import- ant limitations including motor complications termed dyskinesias. Therefore, a pharmacological therapy able to prevent or halt the neu- rodegenerative process is urgently required.

Mitochondrial dysfunction and programmed cell death in osteosarcoma

Osteosarcoma is the most prevalent primarymalignant bone tumor,primarily affecting adolescents aged 15–25 years.It is characterized by a high recurrence rate,poor prognosis,and lack of important biomarkers.Significant mitochondrial dysfunction in osteosarcoma cells has been widely reported by recent studies.Dysfunctional mitochondria occupy an important position in cellularmetabolic reprogramming,immune microenvironment regulation,and programmed cell death.Therefore,targeting mitochondrial dysfunction may represent a new mechanism to overcome therapeutic barriers in the treatment of osteosarcoma and provides crucial target molecules for further development of targeted therapies and immunotherapies.The present article summarizes the recent reports of mitochondrial dysfunction in osteosarcoma and links it to various programmed cell death mechanisms,aiming to provide the basis for further clinical practice.

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(Adipo R)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.

Sirtuin 3 regulation:a target to alleviateβ-hydroxybutyric acid-induced mitochondrial dysfunction in bovine granulosa cells

Background During the transition period,the insufficient dry matter intake and a sharply increased in energy consumption to produce large quantities of milk,high yielding cows would enter a negative energy balance(NEB)that causes an increase in ketone bodies(KBs)and decrease in reproduction efficiency.The excess concentrations of circulating KBs,represented byβ-hydroxybutyric acid(BHBA),could lead to oxidative damage,which potentially cause injury to follicular granulosa cells(fGCs)and delayed follicular development.Sirtuin 3(Sirt3)regulates mitochondria reactive oxygen species(mitoROS)homeostasis in a beneficial manner;however,the molecular mechanisms underlying its involvement in the BHBA-induced injury of fGCs is poorly understood.The aim of this study was to explore the protection effects and underlying mechanisms of Sirt3 against BHBA overload-induced damage of fGCs.Results Our findings demonstrated that 2.4 mmol/L of BHBA stress increased the levels of mitoROS in bovine fGCs.Further investigations identified the subsequent mitochondrial dysfunction,including an increased abnormal rate of mitochondrial architecture,mitochondrial permeability transition pore(MPTP)opening,reductions in mitochondrial membrane potential(MMP)and Ca^(2+)release;these dysfunctions then triggered the caspase cascade reaction of apoptosis in fGCs.Notably,the overexpression of Sirt3 prior to treatment enhanced mitochondrial autophagy by increasing the expression levels of Beclin-1,thus preventing BHBA-induced mitochondrial oxidative stress and mitochondrial dysfunction in fGCs.Furthermore,our data suggested that the AMPK-mTOR-Beclin-1 pathway may be involved in the protective mechanism of Sirt3 against cellular injury triggered by BHBA stimulation.Conclusions These findings indicate that Sirt3 protects fGCs from BHBA-triggered injury by enhancing autophagy,attenuating oxidative stress and mitochondrial damage.This study provides new strategies to mitigate the fGCs injury caused by excessive BHBA stress in dairy cows with ketosis.

YBX1 inhibits mitochondrial-mediated apoptosis in ischemic heart through the PI3K/AKT signaling pathway

Background:Myocardial infarction(MI)is associated with higher morbidity and mortality in the world,especially in cold weather.YBX1 is an RNA-binding protein that is required for pathological growth of cardiomyocyte by regulating cell growth and protein synthesis.But YBX1,as an individual RNA-binding protein,regulates cardiomyocytes through signaling cascades during myocardial infarction remain largely unexplored.Methods:In vivo,the mouse MI model was induced by ligating the left anterior descending coronary artery(LAD),and randomly divided into sham operation group,MI group,MI+YBX1 knockdown/overexpression group and MI+negative control(NC)group.The protective effect of YBX1 was verified by echocardiography and triphenyltetrazolium chloride staining.In vitro,mitochondrial-dependent apoptosis was investigated by using CCK8,TUNEL staining,reactive oxygen species(ROS)staining and JC-1 staining in hypoxic neonatal mouse cardiomyocytes(NMCMs).Results:YBX1 expression of cardiomyocytes was downregulated in a mouse model and a cellular model on the ischemic condition.Compared to mice induced by MI,YBX1 overexpression mediated by adeno-associated virus serotype 9(AAV9)vector reduced the infarcted size and improved cardiac function.Knockdown of endogenous YBX1 by shRNA partially aggravated ischemia-induced cardiac dysfunction.In hypoxic cardiomyocytes,YBX1 overexpression decreased lactic dehydrogenase(LDH)release,increased cell viability,and inhibited apoptosis by affecting the expression of apoptosis related proteins,while knockdown of endogenous YBX1 by siRNA had the opposite effect.Overexpression of YBX1 restored mitochondrial dysfunction in hypoxic NMCMs by increasing mitochondrial membrane potential and ATP content and decreasing ROS.In hypoxic NMCMs,YBX1 overexpression increased the expression of phosphorylated phosphatidylinositol 3 kinase(PI3K)/AKT,and the anti-apoptosis effect of YBX1 was eliminated t by LY294002,PI3K/AKT inhibitor.Conclusion:YBX1 protected the heart from ischemic damage by inhibiting the mitochondrial-dependent apoptosis through PI3K/AKT pathway.It is anticipated that YBX1 may serve as a novel therapeutic target for MI.

Adipsin inhibits Irak2 mitochondrial translocation and improves fatty acid β-oxidation to alleviate diabetic cardiomyopathy

Background Diabetic cardiomyopathy (DCM) causes the myocardium to rely on fatty acid β-oxidation for energy. The accumulation of intracellular lipids and fatty acids in the myocardium usually results in lipotoxicity, which impairs myocardial function. Adipsin may play an important protective role in the pathogenesis of DCM. The aim of this study is to investigate the regulatory effect of Adipsin on DCM lipotoxicity and its molecular mechanism.MethodsA high-fat diet (HFD)-induced type 2 diabetes mellitus model was constructed in mice with adipose tissue-specific overexpression of Adipsin (Adipsin-Tg). Liquid chromatography-tandem mass spectrometry (LC–MS/MS), glutathione-S-transferase (GST) pull-down technique, Co-immunoprecipitation (Co-IP) and immunofluorescence colocalization analyses were used to investigate the molecules which can directly interact with Adipsin. The immunocolloidal gold method was also used to detect the interaction between Adipsin and its downstream modulator.ResultsThe expression of Adipsin was significantly downregulated in the HFD-induced DCM model (P < 0.05). Adipose tissue-specific overexpression of Adipsin significantly improved cardiac function and alleviated cardiac remodeling in DCM (P < 0.05). Adipsin overexpression also alleviated mitochondrial oxidative phosphorylation function in diabetic stress (P < 0.05). LC–MS/MS analysis, GST pull-down technique and Co-IP studies revealed that interleukin-1 receptor-associated kinase-like 2 (Irak2) was a downstream regulator of Adipsin. Immunofluorescence analysis also revealed that Adipsin was co-localized with Irak2 in cardiomyocytes. Immunocolloidal gold electron microscopy and Western blotting analysis indicated that Adipsin inhibited the mitochondrial translocation of Irak2 in DCM, thus dampening the interaction between Irak2 and prohibitin (Phb)-optic atrophy protein 1 (Opa1) on mitochondria and improving the structural integrity and function of mitochondria (P < 0.05). Interestingly, in the presence of Irak2 knockdown, Adipsin overexpression did not further alleviate myocardial mitochondrial destruction and cardiac dysfunction, suggesting a downstream role of Irak2 in Adipsin-induced responses (P < 0.05). Consistent with these findings, overexpression of Adipsin after Irak2 knockdown did not further reduce the accumulation of lipids and their metabolites in the cardiac myocardium, nor did it enhance the oxidation capacity of cardiomyocytes expose to palmitate (PA) (P < 0.05). These results indicated that Irak2 may be a downstream regulator of Adipsin.ConclusionsAdipsin improves fatty acid β-oxidation and alleviates mitochondrial injury in DCM. The mechanism is related to Irak2 interaction and inhibition of Irak2 mitochondrial translocation.

Punicalagin prevents obesity-related cardiac dysfunction through promoting DNA demethylation in mice

The aim of this study was to investigate whether punicalagin(PU)could prevent obesity-related cardiac dysfunction by promoting DNA demethy lation,and to explore its possible mechanism.C57BL/6J mice were fed with standard diet,high-fat diet(HFD),HFD supplemented with resveratrol,low-dose PU(LPU)and high-dose PU(HPU)for 8 weeks.Compared with HFD group,body weight was significantly lower in PU treatment groups,number of cardionwocytes and the protein level of myosin heavy chain 7B were significantly higher in PU treatment groups.Levels of 5-hydroxymethylcytosine and 5-formylcytosine were significantly lower in HFD group than in other groups.Compared with the HFD group,the protein level of ten-eleven translocation enzyme(TET)2 was significantly higher in PU treatment groups,p-AMP-activated protein kinase(AMPK)was significantly higher in LPU group.Levels of total antioxidant capacity and the protein levels of complexesⅡ/Ⅲ/Ⅴ,oxoglutarate dehydrogenase,succinate dehydrogenase B and fumarate hdrolase were significantly lower in HFD group than PU treatment group.The ratio of(succinic acid+fumaric acid)/a-ketoglutarate was significantly higher in HFD group than other groups.In conclusion,PU up-regulated TETs enzyme activities and TET2 protein stability through alleviating mitochondrial dysfunction and activating AMPK,so as to promote DNA demethylation,thus preventing obesity-related cardiac dysfunction.

Hypoglycemic activity of puerarin through modulation of oxidative stress and mitochondrial function via AMPK

Hyperglycemia is the dominant phenotype of diabetes and the main contributor of diabetic complications. Puerarin is widely used in cardiovascular diseases and diabetic vascular complications. However, little is known about its direct effects on diabetes. The aim of our study is to investigate its antidiabetic effect in vivo and in vitro, and explore the underlying mechanism. We used type I diabetic mice induced by streptozotocin to observe the effects of puerarin on glucose metabolism. In addition, oxidative stress and hepatic mitochondrial respiratory activity were evaluated in type I diabetic mice. In vitro, glucose consumption in Hep G2 cells was assayed along with the q PCR detection of glucogenesis genes expression. Moreover, ATP production was examined and phosphorylation of AMPK was determined using Western blot. Finally, the molecular docking was performed to predict the potential interaction of puerarin with AMPK utilizing program Lib Dock of Discovery Studio 2018 software. The results showed that puerarin improved Hep G2 glucose consumption and upregulated the glucogenesis related genes expression. Also, puerarin lowered fasting and fed blood glucose with improvement of glucose tolerance in type I diabetic mice. Further mechanism investigation showed that puerarin suppressed oxidative stress and improved hepatic mitochondrial respiratory function with enhancing ATP production and activating phosphorylation of AMPK. Docking study showed that puerarin interacted with AMPK activate site and enhancing phosphorylation. Taken together, these findings indicated that puerarin exhibited the hypoglycemic effect through attenuating oxidative stress and improving mitochondrial function via AMPK regulation, which may serve as a potential therapeutic option for diabetes treatment.

Glutamine in suppression of lipopolysaccharide-induced piglet intestinal inflammation:The crosstalk between AMPK activation and mitochondrial function

The study was conducted to investigate the regulatory mechanism of glutamine(Gln)on intestinal inflammation in an Escherichia coli lipopolysaccharide(E.coli LPS)-induced in vivo and in vitro models.Piglets(n=8)weaned at 21 d of age were fed a basal diet(control and LPS groups)or 1%Gln diet(Gln t LPS group)ad libitum for 4 weeks.On d 22,24,26 and 28,piglets in the LPS and Gln t LPS groups were intraperitoneally injected with E.coli LPS.Intestinal porcine epithelial cells(IPEC-J2)(n=6)induced by LPS were used to assess related mechanisms and compound C was used to inhibit adenosine 50-monophosphate-activated protein kinase(AMPK)activity.Our current results showed that compared with the LPS treatment,the Gln t LPS treatment had better growth performance and greater villus height(P<0.05),and the Gln t LPS treatment reduced the rate of diarrhea by 6.4%(P<0.05);the Gln t LPS treatment decreased serum tumor necrosis factor(TNF-ɑ),interleukin-6(IL-6),Kt,cortisol and insulin levels,whereas increased(P<0.05)serum immunoglobulin M and epidermal growth factor levels;the Gln t LPS treatment increased(P<0.05)the expression of aquaporins and AMPK pathwayassociated targets in the jejunum and ileum of piglets,whereas decreased the expression of ion transporters(P<0.05).The in vitro results showed that 4 mmol/L Gln administration could inhibit(P<0.05)cell apoptosis and interleukin-1b(IL-1b),IL-6 and TNF-ɑsecretion in LPS-induced IPEC-J2 cells,promote(P<0.05)mitochondrial respiratory metabolism and increase(P<0.05)the number of mitochondria and mitochondrial membrane potential.The activity of AMPK was elevated by 70%to 300%in Gln-treated IPEC-J2 cells under LPS challenge or normal conditions.Our results indicate that pre-administration of Gln to piglets suppresses intestinal inflammation by modulating the crosstalk between AMPK activation and mitochondrial function.

Metformin alleviates cholestasis-associated nephropathy through regulating oxidative stress and mitochondrial function

Background and aim:Cholestasis-associated renal injury or cholemic nephropathy(CN)is a serious clinical problem.Previous studies mentioned that oxidative stress and mitochondrial impairment play a role in CN.There is no specific pharmacological intervention for CN.Metformin is an anti-diabetic drug administered for decades.On the other hand,novel pharmacological properties have emerged for this drug.The effect of metformin on oxidative stress parameters has been well-recognized in different experimental models.It has also been found that metformin positively affected mitochondrial function.The current study aimed to evaluate the effects of metformin in an animal model of CN.Methods:Rats underwent bile duct ligation(BDL)and were treated with metformin(250 and 500 mg/kg)for 14 consecutive days.Two weeks after the BDL operations,urine,serum,and kidney samples were collected and analyzed.Results:Markers of oxidative stress,including reactive oxygen species(ROS)formation,lipid peroxida-tion,protein carbonylation,depleted antioxidant capacity,and decreased glutathione(GSH)levels were detected in BDL animals.Moreover,mitochondrial indices,including adenosine triphosphate(ATP)level,dehydrogenase activity,mitochondrial membrane potential,and mitochondrial permeability,were impaired in the kidney of cholestatic rats.Renal histopathological alterations in cholestatic animals included tubular degeneration and interstitial inflammation,cast formation,and fibrosis.It was found that metformin significantly alleviated oxidative stress and improved mitochondrial indices in the kidney of cholestatic rats.Tissue histopathological alterations were also mitigated in metformin-treated groups.Conclusions:Metformin could be a candidate for managing CN.The nephroprotective role of metformin is primarily associated with its effects on oxidative stress parameters and mitochondrial function.

Value of dynamic 31p magnetic resonance spectroscopy technique in in vivo assessment of the skeletal muscle mitochondrial function in type 2 diabetes

Background Phosphorous magnetic resonance spectroscopy （31p-MRS） has been successfully applied to study intracellular membrane compounds and high-energy phosphate metabolism.This study aimed to evaluate the capability of dynamic 31p-MRS for assessing energy metabolism and mitochondrial function in skeletal muscle from type 2 diabetic patients.Methods Dynamic 31p-MRS was performed on 22 patients with type 2 diabetes and 26 healthy volunteers.Spectra were acquired from quadriceps muscle while subjects were in a state of rest,at exercise and during recovery.The peak areas of inorganic phosphate （Pi）,phosphocreatine （PCr）,and adenosine triphosphate （ATP） were measured.The concentration of adenosine diphosphate （ADP） and the intracellular pH value were calculated from the biochemistry reaction equilibrium.The time constant and recovery rates of Pi,PCr,and ADP were analyzed using exponential curve fitting.Results As compared to healthy controls,type 2 diabetes patients had significantly lower skeletal muscle concentrations of Pi,PCr and β-ATP,and higher levels of ADP and Pi/PCr.During exercise,diabetics experienced a significant Pi peak increase and PCr peak decrease,and once the exercise was completed both Pi and PCr peaks returned to resting levels.Quantitatively,the mean recovery rates of Pi and PCr in diabetes patients were （10.74±1.26） mmol/s and （4.74±2.36） mmol/s,respectively,which was significantly higher than in controls.Conclusions Non-invasive quantitative 31P-MRS is able to detect energy metabolism inefficiency and mitochondrial function impairment in skeletal muscle of type 2 diabetics.

Knockdown of insulin-like growth factor 2 gene disrupts mitochondrial functions in the liver

Even though insulin-like growth factor 2(IGF2)has been reported to be overexpressed in nonalcoholic fatty liver disease(NAFLD),its role in the progression of NAFLD and the potential mechanism remain largely unclear.Using in vitro models,we found that IGF2 was the key overexpressed gene in steatosis,suggesting a possible association between IGF2 and NAFLD.Interestingly,loss-of-function experiments revealed that inhibition of IGF2 protein impaired mitochondrial biogenesis and respiration.It additionally disrupted the expression changes of mitochondrial fusion and fission-related proteins necessary in maintaining mitochondrial homeostasis.Consistently,IGF2 knockdown reduced the mitochondrial membrane potential and increased the production of reactive oxygen species.Mechanistically,IGF2 regulates mitochondrial functions by modulating the expression of SIRT1 and its downstream gene PGCla.This research opens a new frontier on the role of IGF2 in energy metabolism,which potentially participates in the development of NAFLD.As such,IGF2 is a potential therapeutic target against NAFLD.

Maternal zinc alleviates tert-butyl hydroperoxide-induced mitochondrial oxidative stress on embryonic development involving the activation of Nrf2/PGC-1αpathway

Background Mitochondrial dysfunction induced by excessive mitochondrial reactive oxygen species(ROS)damages embryonic development and leads to growth arrest.Objective The purpose of this study is to elucidate whether maternal zinc(Zn)exert protective effect on oxidative stress targeting mitochondrial function using an avian model.Result In ovo injected tert-butyl hydroperoxide(BHP)increases(P<0.05)hepatic mitochondrial ROS,malondialdehyde(MDA)and 8-hydroxy-2-deoxyguanosine(8-OHdG),and decreases(P<0.05)mitochondrial membrane potential(MMP),mitochondrial DNA(mtDNA)copy number and adenosine triphosphate(ATP)content,contributing to mitochondrial dysfunction.In vivo and in vitro studies revealed that Zn addition enhances(P<0.05)ATP synthesis and metallothionein 4(MT4)content and expression as well as alleviates(P<0.05)the BHP-induced mitochondrial ROS generation,oxidative damage and dysfunction,exerting a protective effect on mitochondrial function by enhancing antioxidant capacity and upregulating the mRNA and protein expressions of Nrf2 and PGC-1α.Conclusions The present study provides a new way to protect offspring against oxidative damage by maternal Zn supplementation through the process of targeting mitochondria involving the activation of Nrf2/PGC-1αsignaling.

Abnormal mitochondrial function impairs calcium influx in diabetic mouse pancreatic beta cells

Background Abnormal insulin secretion of pancreatic beta cells is now regarded as the more primary defect than the insulin function in the etiology of type 2 diabetes.Previous studies found impaired mitochondrial function and impaired Ca2＋ influx in beta cells in diabetic patients and animal models,suggesting a role for these processes in proper insulin secretion.The aim of this study was to investigate the detailed relationship of mitochondrial function,Ca2＋ influx,and defective insulin secretion.Methods We investigated mitochondrial function and morphology in pancreatic beta cell of diabetic KK-Ay mice and C57BL/6J mice.Two types of Ca2＋ channel activities,L-type and store-operated Ca2＋ （SOC）,were evaluated using whole-cell patch-clamp recording.The glucose induced Ca2＋ influx was measured by a non-invasive micro-test technique （NMT）.Results Mitochondria in KK-Ay mice pancreatic beta cells were swollen with disordered cristae,and mitochondrial function decreased compared with C57BL/6J mice.Ca2＋ channel activity was increased and glucose induced Ca2＋ influx was impaired,but could be recovered by genipin.Conclusion Defective mitochondrial function in diabetic mice pancreatic beta cells is a key cause of abnormal insulin secretion by altering Ca2＋ influx,but not via Ca2＋ channel activity.

Shenmai Injection attenuated doxorubicin-induced cardiac dysfunction via maintaining mitochondrial homeostasis

OBJECTIVE Shenmai Injection(SMI)is widely used in the treatment of cardiovascular diseases,such as heart failure and myocardial ischemia.In clinic,SMI showed protective effects on doxorubicin(Dox)-induced cardiac toxicity.In current study,we investigate the mitochondrial protective mechanisms of SMI on Dox-induced myocardial injury.METHODS C57BL/6 mice were divided into four groups:①control group;②Dox injury group;③SMI+Dox group and dexrazoxane(DRZ)+Dox group.Dex was a positive control.Myocardial injury was evaluated by echocardiography,HE and TUNEL staining,myocardial markers measurement.H9C2 cardiomyocytes pretreatment with SMI for 24 h were exposed to Dox.Cell viability and apoptosis were measured by CCK8,Hoechst33342 staining,and Annexin V/PI staining.MitoSOX,mitochondrial membrane potential,and mitochondrial respiratory function were measured to evaluate mito⁃chondrial function.RESULTS SMI decreased mortality rate of Dox-injected mice,serum CK and CK-MB levels in vivo.SMI significantly prevented Dox-induced cardiac dysfunction and apoptosis and increased expression level of PI3K,p-Akt,and p-GSK-3β.Moreover,SMI significantly inhibited Dox-induced apoptosis,mitochondrial ROS production,and reduction of mitochondrial membrane potential in H9C2 cells.Mechanismly,the cardio-protective effect of SMI was suppressed by PI3K inhibitor LY294002.CONCLUSION SMI prevents Dox-induced cardiotoxicity and mitochondrial damage through activation of PI3K/Akt signaling pathway.