T_3-induced liver AMP-activated protein kinase signaling:Redox dependency and upregulation of downstream targets

AIM: To investigate the redox dependency and promotion of downstream targets in thyroid hormone (T3)-induced AMP-activated protein kinase (AMPK) signaling as cellular energy sensor to limit metabolic stresses in the liver.

Gene expression profiles and phosphorylation patterns of AMP-activated protein kinase subunits in various mesenchymal cell types

Background Recent studies on bone have shown an endocrine role of the skeleton,which could be impaired in various human diseases,including osteoporosis,obesity,and diabetes-associated bone diseases.As a sensor and regulator of energy metabolism,AMP-activated protein kinase （AMPK） may also play an important role in the regulation of bone metabolism.The current study aimed to establish the expression profiles and phosphorylation patterns of AMPK subunits in several mesenchymal cell types.Methods Reverse transcription-polymerase chain reaction （PCR） for relative quantification,real-time PCR for absolute quantification,and Western blotting were used to investigate the gene expression profiles and phosphorylation patterns of AMPK subunits in several mesenchymal cell types,including primary human mesenchymal stem cells （hMSCs） and hFOB,Saos-2,C3H/10T1/2,MC3T3-E1,3T3-L1,and C2C12 cells.Results AMPKα1 and AMPKβ1 mRNAs were abundantly expressed in all cell types.AMPKY1 mRNA was abundantly expressed in C3H/10T1/2,MC3T3-E1,3T3-L1,and C2C12 but not detected in human-derived cell types.AMPKY2 mRNA was mildly expressed in all cell types.AMPKα1 protein was highly expressed in all cell types and AMPKα2 protein was highly expressed only in hFOB and Saos-2 cells.AMPKβ1 protein was abundantly expressed in all cell types except for Saos-2,in which AMPKβ2 protein overwhelmed AMPKβ1 expression.AMPKy1 and AMPKY2 proteins were expressed in C3H/10T1/2,MC3T3-E1,3T3-L1,and C2C12 cells and only AMPKY2 protein was expressed in hMSCs,hFOB and Saos2 cells.AMPKα was phosphorylated at Thr172 and Ser485 and AMPKβ1 was phosphorylated at Ser108 and Ser182 in all cell types with a specific pattern in each cell type.Conclusion The combination of AMPK α,β,and Y subunits and phosphorylation of AMPKα （Thr172 and Ser485） and AMPKβ1 （Ser108 and Ser182） showed a specific pattern in each cell type.

Regulation of AMP-activated protein kinase by natural and synthetic activators

The AMP-activated protein kinase(AMPK)is a sensor of cellular energy status that is almost universally expressed in eukaryotic cells.While it appears to have evolved in single-celled eukaryotes to regulate energy balance in a cell-autonomous manner,during the evolution of multicellular animals its role has become adapted so that it also regulates energy balance at the whole body level,by responding to hormones that act primarily on the hypothalamus.AMPK monitors energy balance at the cellular level by sensing the ratios of AMP/ATP and ADP/ATP,and recent structural analyses of the AMPK heterotrimer that have provided insight into the complex mechanisms for these effects will be discussed.Given the central importance of energy balance in diseases that are major causes of morbidity or death in humans,such as type 2 diabetes,cancer and inflammatory disorders,there has been a major drive to develop pharmacological activators of AMPK.Many such activators have been described,and the various mechanisms by which these activate AMPK will be discussed.A particularly large class of AMPK activators are natural products of plants derived from traditional herbal medicines.While the mechanism by which most of these activate AMPK has not yet been addressed,I will argue that many of them may be defensive compounds produced by plants to deter infection by pathogens or grazing by insects or herbivores,and that many of them will turn out to be inhibitors of mitochondrial function.

Cordycepin promotes browning of white adipose tissue through an AMP-activated protein kinase(AMPK)-dependent pathway

Obesity is a worldwide epidemic. Promoting browning of white adipose tissue(WAT)contributes to increased energy expenditure and hence counteracts obesity. Here we show that cordycepin(Cpn), a natural derivative of adenosine, increases energy expenditure, inhibits weight gain, improves metabolic profile and glucose tolerance, decreases WAT mass and adipocyte size, and enhances cold tolerance in normal and high-fat diet-fed mice. Cpn markedly increases the surface temperature around the inguinal WAT and turns the inguinal fat browner. Further investigations show that Cpn induces the development of brown-like adipocytes in inguinal and, to a less degree, epididymal WAT depots. Cpn also increases the expression of uncoupling protein 1(UCP1) and other thermogenic genes in WAT and3T3-L1 differentiated adipocytes, in which AMP-activated protein kinase(AMPK) plays an important role. Our results provide novel insights into the function of Cpn in regulating energy balance, and suggest a potential utility of Cpn in the treatment of obesity.

A potential strategy for treating atherosclerosis： improving endothelial function via AMP-activated protein kinase

Endothelial dysfunction is caused by many factors, such as dyslipidemia, endoplasmic reticulum(ER) stress, and inflammation.It has been demonstrated that endothelial dysfunction is the initial process of atherosclerosis. AMP-activated protein kinase(AMPK) is an important metabolic switch that plays a crucial role in lipid metabolism and inflammation. However, recent evidence indicates that AMPK could be a target for atherosclerosis by improving endothelial function. For instance, activation of AMPK inhibits the production of reactive oxygen species induced by mitochondrial dysfunction, ER stress, and NADPH oxidase. Moreover, activation of AMPK inhibits the production of pro-inflammatory factors induced by dyslipidemia and hyperglycemia and restrains production of perivascular adipose tissue-released adipokines. AMPK activation prevents endothelial dysfunction by increasing the bioavailability of nitric oxide. Therefore, we focused on the primary risk factors involved in endothelial dysfunction, and summarize the features of AMPK in the protection of endothelial function, by providing signaling pathways thought to be important in the pathological progress of risk factors.

Mixture of five herbal extracts ameliorates pioglitazone-induced aggravation of hepatic steatosis via activating the adiponectin receptor 2/AMP-activated protein kinase signal pathway in diabetic KKAy mice

OBJECTIVE: To assess the effect of a mixture of five herbal extracts(FT-5) on insulin resistance, glucose/lipid metabolism, hepatic steatosis, and to investigate whether the combination of FT-5 and pioglitazone would provide a robust effect on diabetes treatment, while may minimize undesirable side-effects of pioglitazone in diabetic Ay gene(KKAy)mice.METHODS: Seven-week-old KKAy mice were randomly divided into five groups: control(CON)group, FT-5(2.0 g/kg) group, pioglitazone(20 mg/kg)(PIO) group, pioglitazone(20 mg/kg) + FT-5(2.0 g/kg)(P + F) group. Age-matched C57 BL/6 J micewere used as the control group. After seven weeks of continuous intragastric administration of medication, the glucose metabolism, insulin sensitivity and lipid metabolism of KKAy mice were evaluated by assessing the fasting blood glucose(FBG), oral glucose tolerance test(OGTT), fasting serum insulin(FINS), insulin tolerance test(ITT), homeostasis model of assessment-insulin resistance index(HOMA-IR), total cholesterol(TC), total triglycerides(TG), and free fatty acids(FFA) in plasma and liver.Plasma and hepatic adiponectin were measured via enzyme-linked immunosorbent assays. Genes related to adipogenesis and lipolysis in white adipose tissues(WAT) and liver were examined by real-time polymerase chain reaction. Lipid metabolism-related protein expression in the liver of KKAy mice were detected by Western blotting.RESULTS: PIO treatment remarkably improved insulin resistance. However, it also showed substantial side effects. FT-5 group exhibited no significant decrease in serum glucose. However, it reduced fasting plasma TG levels and improved hepatic steatosis of KKAy mice. P + F group showed improved insulin resistance and similar body weight gain, as compared with control group. The m RNA expression of genes related to fatty acid oxidation was markedly up-regulated in the liver of P + F group.Pioglitazone administration markedly decreased the phosphorylation levels of AMPK, as compared with all other groups. Besides, even though plasma adiponectin increased in PIO, FT-5, P + F group, adipo R2 gene expression significantly decreased in the liver of PIO group.CONCLUSION: FT-5 decreased plasma TG and alleviated aggravating hepatic steatosis induced by pioglitazone in KKAy mice. FT-5's mechanism might be associated with its ability to activate the Adipo R2/AMPK pathway.

Ginsenoside Rb1 alleviates chronic intermittent hypoxia-induced diabetic cardiomyopathy in db/db mice by regulating the adenosine monophosphate-activated protein kinase/Nrf2/heme oxygenase-1 signaling pathway

OBJECTIVE:To examine the protective effect of ginsenoside Rb1(Rb1),the main component of Renshen(Radix Ginseng),on cardiomyopathy in db/db mice exposed to chronic intermittent hypoxia(CIH)and explore the potential underlying mechanism of Rb1 in treating diabetic cardiomyopathy(DCM).METHODS:The db/db mice were randomly separated into five groups:normal control group,model group,Rb120 mg/kg group,Rb140 mg/kg group,and glucagon-like peptide-1(GLP-1)group.Mice were exposed to aircondition or CIH for 8 weeks,and Rb1 and GLP-1 were administrated before CIH exposure every day.Oral glucose tolerance test(OGTT),intraperitoneal insulin tolerance test(IPITT),total cholesterol(TC),triglyceride(TG),and high-density lipoprotein cholesterol(HDL-C)were detected to evaluate glycolipid metabolism.The level of insulin was detected by a mouse enzyme-linked immunosorbent assay(ELISA).Cardiac function was detected by echocardiography,and myocardial pathology was observed by hematoxylin-eosin and Masson staining.The expression of collagenⅠand collagenⅢwas detected by immunohistochemistry.Adenosine monophosphate-activated protein kinase(AMPK)/Nrf2/heme oxygenase-1(HO-1)signaling pathway was detected by Western blot and immunofluorescence.RESULTS:Rb1 treatment could improve glucose tolerance and the level of cardiac function indexes,and inhibit the level of oxidative stress indexes and the expression of collagenⅠand collagenⅢ.Moreover,Rb1 treatment enhanced AMPK phosphorylation and increased Nrf2 and HO-1 expression.CONCLUSION:Rb1 treatment alleviated CIH-induced diabetic cardiomyopathy and glycolipid metabolism disorders in db/db mice by inhibiting oxidative stress and regulating the AMPK/Nrf2/HO-1 signaling pathway.

Cardiovascular and nonalcoholic fatty liver disease:Sharing common ground through SIRT1 pathways

As a non-communicable disease,cardiovascular disorders have become the lea-ding cause of death for men and women.Of additional concern is that cardio-vascular disease is linked to chronic comorbidity disorders that include nonal-coholic fatty liver disease(NAFLD).NAFLD,also termed metabolic-dysfunction-associated steatotic liver disease,is the greatest cause of liver disease throughout the world,increasing in prevalence concurrently with diabetes mellitus(DM),and can progress to nonalcoholic steatohepatitis that leads to cirrhosis and liver fi-brosis.Individuals with metabolic disorders,such as DM,are more than two times likely to experience cardiac disease,stroke,and liver disease that includes NAFLD when compared individuals without metabolic disorders.Interestingly,cardiovascular disorders and NAFLD share a common underlying cellular me-chanism for disease pathology,namely the silent mating type information regu-lation 2 homolog 1(SIRT1;Saccharomyces cerevisiae).SIRT1,a histone deacetylase,is linked to metabolic pathways through nicotinamide adenine dinucleotide and can offer cellular protection though multiple avenues,including trophic factors such as erythropoietin,stem cells,and AMP-activated protein kinase.Translating SIRT1 pathways into clinical care for cardiovascular and hepatic disease can offer significant hope for patients,but further insights into the complexity of SIRT1 pathways are necessary for effective treatment regimens.

Targeting AMPKa1 Gene in PC3 Cells by Triphenylmethanol Derivatives

Epidemiological studies indicate that treatment with metformin, an AMP-activated protein kinase (AMPK) activator, reduces the incidence of cancers. Activation of AMPK has also been reported to oppose tumor progression in diverse types of cancers and offers promising cancer therapy. Furthermore, AMPK is a primary regulator of energy metabolism and has also been implicated in cell cycle progression, angiogenesis, cell transformation, migration, and cancer. We have recently synthesized novel flavonoids, namely, triphenylmethanol derivatives (TPMs), but the effectiveness of the TPMs on the activity of AMPK remains unclear. We hypothesized that the novel TPMs would inhibit cancer cell proliferation through the activation of AMPK isoforms in cells. The effects of TPMs on prostate cells (PC-3) were investigated. Cells were exposed to TPMs for either 12 or 24 hr. at the respective doses of 0, 25, 50 100, and 200 µM based on the cell viability studies by the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a tetrazole) (MTT) assay. The results indicate that cells exposed to the respective doses of TPMs increased both phospho- and total-AMPKα1 in a dose- and time-dependent manner. The effects of the increases for the phospho- and total-AMPKα in cells were greater for the 24-hr than the 12-hr. incubation. Further studies are currently going on to elucidate the specificities of the said insults in increasing the phospho- and total-AMPKα activities and for the other respective isoforms.

Mechanisms mediating the effects of alcohol and HIV anti-retroviral agents on mTORC1,mTORC2 and protein synthesis in myocytes

Alcoholism and acquired immune deficiency syndrome are associated with severe muscle wasting.This impairment in nitrogen balance arises from increased protein degradation and a decreased rate of protein synthesis.The regulation of protein synthesis is a complex process involving alterations in the phosphorylation state and protein-protein interaction of various components of the translation machinery and mammalian target of rapamycin(mTOR) complexes.This review describes mechanisms that regulate protein synthesis in cultured C2C12 myocytes following exposure to either alcohol or human immunodeficiency virus antiretroviral drugs.Particular attention is given to the upstream regulators of mTOR complexes and the downstream targets which play an important role in translation.Gaining a better understanding of these molecular mechanisms could have important implications for preventing changes in lean body mass in patients with catabolic conditions or illnesses.

Bexarotene improves motor function after spinal cord injury in mice

Spinal cord injury is a challenge in orthopedics because it causes irreversible damage to the central nervous system.Therefore,early treatment to prevent lesion expansion is crucial for the management of patients with spinal cord injury.Bexarotene,a type of retinoid,exerts therapeutic effects on patients with cutaneous T-cell lymphoma and Parkinson's disease.Bexarotene has been proven to promote autophagy,but it has not been used in the treatment of spinal cord injury.To investigate the effects of bexarotene on spinal cord injury,we established a mouse model of T11–T12 spinal cord contusion and performed daily intraperitoneal injection of bexarotene for 5 consecutive days.We found that bexarotene effectively reduced the deposition of collagen and the number of pathological neurons in the injured spinal cord,increased the number of synapses of nerve cells,reduced oxidative stress,inhibited pyroptosis,promoted the recovery of motor function,and reduced death.Inhibition of autophagy with 3-methyladenine reversed the effects of bexarotene on spinal cord injury.Bexarotene enhanced the nuclear translocation of transcription factor E3,which further activated AMP-activated protein kinase-S-phase kinase-associated protein 2-coactivator-associated arginine methyltransferase 1 and AMP-activated protein kinase-mammalian target of rapamycin signaling pathways.Intravenous injection of transcription factor E3 sh RNA or intraperitoneal injection of compound C,an AMP-activated protein kinase blocker,inhibited the effects of bexarotene.These findings suggest that bexarotene regulates nuclear translocation of transcription factor E3 through the AMP-activated protein kinase-Sphase kinase-associated protein 2-coactivator-associated arginine methyltransferase 1 and AMP-activated protein kinase-mammalian target of rapamycin signal pathways,promotes autophagy,decreases reactive oxygen species level,inhibits pyroptosis,and improves motor function after spinal cord injury.

5'-Monophosphate-activated protein kinase (AMPK) improves autophagic activity in diabetes and diabetic complications

Diabetes mellitus(DM),an endocrine disorder,will be one of the leading causes of death world-wide in about two decades.Cellular injuries and disorders of energy metabolism are two key factors in the pathogenesis of diabetes,which also become the important causes for the process of diabetic complications.AMPK is a key enzyme in maintaining metabolic homeostasis and has been implicated in the activation of autophagy in distinct tissues.An increasing number of researchers have confirmed that autophagy is a potential factor to affect or induce diabetes and its complications nowadays,which could remove cytotoxic proteins and dysfunctional organelles.This review will summarize the regulation of autophagy and AMPK in diabetes and its complications,and explore how AMPK stimulates autophagy in different diabetic syndromes.A deeper understanding of the regulation and activity of AMPK in autophagy would enhance its development as a promising therapeutic target for diabetes treatment.

Effect of Yiqihuoxue prescription on myocardial energy metabolism after myocardial infarction via cross talk of liver kinase B1-depen-dent Notch1 and adenosine 5'-monophosphate-activated protein kinase

OBJECTIVE: To investigate the effect of Yiqihuoxue prescription(YQHX) from Traditional Chinese Medicine(TCM) on myocardial glucose and lipid metabolism after myocardial infarction via the cross talk between the liver kinase B1(LKB1)-dependent Notch1 and adenosine 5'-monophosphate(AMP)-activated protein kinase(AMPK). YQHX was prepared with substances with properties that benefit, to activate blood circulation based on the TCM theory.METHODS: Animal models of myocardial infarction were established by ligating Sprague Dawley rats' left anterior descending coronary arteries. The animals were randomly divided into a myocardial infarction(MI) group, a YQHX group, a perindopril group, a γ-secretase inhibitor, Notch signal inhibitor(DAPT) group, a DAPT+YQHX group and a sham group. The related drugs were administered on the second day after operation, and changes in the relevant indexes were examined on weeks 1 and 4.Changes in cardiac structure and function were examined by echocardiography. The glucose and free fatty acids(FFA) were examined by ELISA. The expression of Notch, LKB1 and AMPK m RNA was examined by a real-time fluorescence quantitative method. The expression of glucose transporter 4(GLUT4), and the expression of total acetyl-Co A carboxylase(ACC) and its phosphorylation were examined by western blotting.RESULTS: Compared with the sham group, the expression of Notch, LKB1 and AMPK m RNA in the MI group was lower. Compared with the MI group, the expression of these m RNAs in the YQHX and perindopril groups was higher, and their expression in the DAPT group was lower. At all time points, the protein expression of GLUT4 and p ACC decreased in the MI group. On week 1, the expression of p ACC protein was higher. In the DAPT group, the expression of p ACC protein decreased. Compared with the YQHX group, the expression of p ACC protein in the DAPT + YQHX group was lower. On week 4,compared with the MI group, the expression of GLUT4 protein in the YQHX group and the perindo-pril group was higher. The expression of GLUT4 protein in the DAPT group decreased. Compared with the YQHX group, the expression of GLUT4 protein in the DAPT+YQHX group was lower. There was no significant difference in the expression of ACC protein between the groups.CONCLUSION: YQHX promoted cross talk between the LKB1-dependent Notch1 and AMPK in myocardial tissue after myocardial infarction. Furthermore,it regulated the glucose and lipid metabolism of cardiomyocytes at different time points, thereby ameliorating the cardiac energy metabolism via different mechanisms and protecting the heart.

Efficacy of Sijunzi decoction(四君子汤) on limb weakness in spleen Qi deficiency model rats through adenosine monophosphate-activated protein kinase/unc-51 like autophagy activating kinase 1 signaling

OBJECTIVE:To investigate the efficacy of Sijunzi decoction(四君子汤)on limb weakness in a rat model of spleen Qi deficiency(SQD),and to study its effect on mitophagy in skeletal muscle through adenosine monophosphate-activated protein kinase(AMPK)/unc-51 like autophagy activating kinase 1(ULK1)signaling.METHODS:SQD model rats were produced by fasting combined with forced swimming method for15 d.After model assessment,rats were randomly divided into four groups of 10[low/middle/high(L/M/H)Sijunzi decoction dose groups and a normal saline(S)group].Limb holding power(HP)and body mass(BM)were measured after 2 weeks of treatment.Following euthanasia,quadriceps femoris were dissected and myofiber and mitochondrial morphology were observed by transmission electron microscopy(TEM).Mitochondrial membrane potential(MMP),adenosine triphosphatase(ATP)and reactive oxygen species(ROS)levels were determined using colorimetric methods,and immunoblot analysis of Microtubule-associated protein light chain 3(LC3)and Sequestosome 1(p62)was performed to monitor mitophagy and AMPK/ULK1 signaling.RESULTS:Compared with control(C)group rats,in the S group,HP was reduced,the myofiber Z line was disordered,mitochondria were scattered,and numerous vacuoles and mitophagy were observed.MMP and ATP levels were reduced,ROS levels were elevated,and LC3B expression,and p-AMPKα(Thr172)/AMPKα,p-ULK1(Ser555)/ULK1,and p-Raptor(Ser792)/Raptor ratios were increased,while p62 expression and p-mT OR(Ser2448)/mT OR and p-ULK1(Ser757)/ULK1 ratios were decreased.After treatment,compared with the S group,HP was improved in M and H groups but not in the L group.Mitophagy was reduced in M,H and L groups but the Z line was disordered and vacuolization remained in the L group.ATP levels were elevated in M,H and L groups,and MMPs were elevated in M and H groups but not in the L group.ROS levels were decreased in M,H and L groups,as were LC3B expression and p-Raptor(Ser792)/Raptor ratios,while p62 expression and p-mT OR(Ser2448)/mT OR and p-ULK1(Ser757)/ULK1 ratios were increased in M and H groups but not in the L group.p-AMPKα(Thr172)/AMPKαand p-ULK1(Ser555)/ULK1 ratios were decreased in M,H and L groups.CONCLUSIONS:Sijunzi decoction improved HP,possibly by inhibiting mitophagy via suppression of AMPK/ULK1 signaling.This restored mitochondrial morphology and improved oxidative phosphorylation,which contributed to recovery of limb weakness in SQD model rats.

Anti-hypertensive and endothelia protective effects of Fufang Qima capsule(复方芪麻胶囊) on primary hypertension via adiponectin/adenosine monophosphate activated protein kinase pathway

OBJECTIVE:To investigate the potential mechanism of the vascular remodeling effect and provide additional information about anti-hypertension activity of Fufang Qima capsule(复方芪麻胶囊,QM).METHODS:Spontaneous hypertensive rats(SHRs)were used to study the underlying mechanism of the anti-hypertension activity of QM.In this study,SHRs were randomly divided into 5 groups:model group,Telmisartan group(7.2 mg/kg,p.o.),and three QM groups(0.9298,1.8596,and 3.7192 g/kg,p.o.).Wistar Kyoto rats(WKY)were used as normal control group.Blood pressure(BP),aorta,perivascular adipose tissue(PVAT)histology were investigated to evaluate the effect of QM.Nitric oxide(NO)and endothelial nitric oxide synthase(eNOS)phosphorylation were measured.Adiponectin(APN)secretion,as well as APN signal pathway proteins including APN,adiponectin receptors(R1 and R2)and adenosine 5’-monophosphate-activated protein kinase(AMPK)were all analyzed.RESULTS:QM significantly reduced BP and ameliorated the vascular pathological change,i.e.intima media thicken and collagen fiber hyperplasia.Meanwhile,QM increased concentration of NO and the phosphorylation of eNOS in the aorta.The anti-hypertensive and endothelia-protective effect of QM could be attributed to activating APN/AMPK pathway by up-regulating the expression of APN in PVAT and APN Receptor 2,AMPKαand phosphorylated AMPKαin the aorta.CONCLUSION:The QM alleviation effect mechanism for primary hypertension was via modulating the APN/AMPK signal pathway.

二甲双胍抑制高糖状态下大鼠肾小球系膜细胞增殖作用机制的进一步研究

目的探讨二甲双胍抑制高糖状态下大鼠肾小球系膜细胞增殖的作用机制。方法体外培养大鼠肾小球系膜细胞(HBZY-1)分为2组,AICAR组分为正常对照(NC)组(葡萄糖浓度5.6 mmol/L)、高糖(HG)组(葡萄糖浓度30 mmol/L)、HG+AICAR组(葡萄糖浓度30 mmol/L+AICAR浓度2.0 mmol/L)、HG+AICAR+二甲双胍组(葡萄糖浓度30 mmol/L+AICAR浓度2.0 mmol/L+二甲双胍浓度200 mmol/L)4个亚组,Compound C组分为NC组、HG组、HG+Compound C组(葡萄糖浓度30 mmol/L+Compound C浓度0.5 mmol/L)、HG+Compound C+二甲双胍组(葡萄糖浓度30 mmol/L+Compound C浓度0.5 mmol/L+二甲双胍浓度200 mmol/L)4个亚组,作用时间均为24 h,MTT法检测各组HBZY-1细胞增殖的情况;如上分组,作用12 h,用Western blot法检测各组细胞内p-单磷酸腺苷激活的蛋白激酶(p-AMPK)和AMPK蛋白表达的变化。结果①与NC组相比,高糖刺激24 h后HBZY-1增殖明显(P均<0.01);与HG组相比,加AICAR干预后HBZY-1增殖明显抑制,加Compound C干预后系膜细胞进一步增殖,均有显著性差异(P均<0.01);与HG+AICAR组相比,加二甲双胍干预后HBZY-1增殖进一步抑制,有显著性差异(P<0.01);与HG+Compound C组相比,加二甲双胍干预后HBZY-1增殖明显抑制,有显著性差异(P<0.01);②与NC组相比,高糖刺激24 h后HBZY-1细胞内p-AMPK表达水平明显下降(P均<0.01);与HG组相比,加AICAR干预后p-AMPK表达水平明显升高,加Compound C干预后p-AMPK表达水平进一步下降,均有显著性差异(P均<0.01);与HG+AICAR组相比,加二甲双胍干预后HBZY-1细胞内p-AMPK表达水平进一步升高,有显著性差异(P<0.01);与HG+Compound C组相比,加二甲双胍干预后p-AMPK表达水平明显升高,有显著性差异(P<0.01)。结论二甲双胍可能通过增加肾小球系膜细胞内p-AMPK的表达水平来抑制HBZY-1的增殖。

腺苷酸活化蛋白激酶(AMPK)活性对动物宰后糖酵解的影响

动物宰后其骨骼肌的能量代谢是影响宰后肉品品质的重要因素之一。在动物宰后的糖酵解中,腺苷酸蛋白活化激酶(AMP-activated proteinkinase,AMPK)可以通过对糖酵解关键限速酶活性的控制进而对宰后的糖酵解和肉的品质产生影响。文中综述了AMPK结构、其活性变化及活性调控对宰后糖酵解进程的影响,并对通过AMPK活性的人工调控来改善肉质提出了展望。

Green tea polyphenols ameliorate non-alcoholic fatty liver disease through upregulating AMPK activation in high fat fed Zucker fatty rats

AIM To investigate protective effects and molecular mechanisms of green tea polyphenols(GTP) on nonalcoholic fatty liver disease(NAFLD) in Zucker fatty(ZF) rats.METHODS Male ZF rats were fed a high-fat diet(HFD) for 2 wk then treated with GTP(200 mg/kg) or saline(5 m L/kg) for 8 wk, with Zucker lean rat as their control. At the end of experiment, serum and liver tissue were collected for measurement of metabolic parameters, alanine aminotransferase(ALT) and aspartate aminotransferase(AST), inflammatory cytokines and hepatic triglyceride and liver histology. Immunoblotting was used to detect phosphorylation of AMP-activated protein kinase(AMPK) acetyl-Co A carboxylase(ACC), and sterol regulatory element-binding protein 1c(SREBP1c). RESULTS Genetically obese ZF rats on a HFD presented with metabolic features of hepatic pathological changes comparable to human with NAFLD. GTP intervention decreased weight gain(10.1%, P = 0.052) and significantly lowered visceral fat(31.0%, P < 0.01). Compared with ZF-controls, GTP treatment significantly reduced fasting serum insulin, glucose and lipids levels. Reduction in serum ALT and AST levels(both P < 0.01) were observed in GTP-treated ZF rats. GTP treatment also attenuated the elevated TNFα and IL-6 in the circulation. The increased hepatic TG accumulation and cytoplasmic lipid droplet were attenuated by GTP treatment, associated with significantly increased expression of AMPK-Thr172(P < 0.05) and phosphorylated ACC and SREBP1c(both P < 0.05), indicating diminished hepatic lipogenesis and triglycerides out flux from liver in GTP treated rats. CONCLUSION The protective effects of GTP against HFD-induced NAFLD in genetically obese ZF rats are positively correlated to reduction in hepatic lipogenesis through upregulating the AMPK pathway.

LB100 ameliorates nonalcoholic fatty liver disease via the AMPK/Sirt1 pathway

BACKGROUND It is well known that nonalcoholic fatty liver disease(NAFLD)is associated with insulin resistance(IR).LB100,a serine/threonine protein phosphatase 2A(PP2A)inhibitor,is closely related to IR.However,there is little data regarding its direct influence on NAFLD.AIM To elucidate the effect and underlying mechanism of LB100 in NAFLD.METHODS After 10 wk of high fat diet(HFD)feeding,male C57BL/6 mice were injected intraperitoneally with vehicle or LB100 for an additional 6 wk(three times a week).The L02 cell line was treated with LB100 and free fatty acids(FFAs)for 24 h.Hematoxylin and eosin and oil red O staining were performed for histological examination.Western blot analysis was used to detect the protein expression of Sirtuin 1(Sirt1),total and phosphorylated AMP-activated protein kinaseα(AMPKα),and the proteins involved in lipogenesis and fatty acid oxidation.The mRNA levels were determined by qPCR.Pharmacological inhibition of AMPK was performed to further examine the exact mechanism of LB100 in NAFLD.RESULTS LB100 significantly ameliorated HFD-induced obesity,hepatic lipid accumulation and hepatic injury in mice.In addition,LB100 significantly downregulated the protein levels of acetyl-CoA carboxylase,sterol regulatory element-binding protein 1 and its lipogenesis target genes,including stearoyl-CoA desaturase-1 and fatty acid synthase,and upregulated the levels of proteins involved in fatty acidβ-oxidation,such as peroxisome proliferator-activated receptorα(PPARα),peroxisome proliferator-activated receptor gamma coactivator-1α(PGC-1α),carnitine palmitoyltransferase 1α,acyl-CoA oxidase 1 and uncoupling protein 2,as well as the upstream mediators Sirt1 and AMPKαin the livers of HFD-fed mice.In vitro,LB100 alleviated FFA-induced lipid accumulation in L02 cells through the AMPK/Sirt1 signaling pathway.Further studies showed that the curative effect of LB100 on lipid accumulation was abolished by inhibiting AMPKαin L02 cells.CONCLUSION PP2A inhibition by LB100 significantly ameliorates hepatic steatosis by regulating hepatic lipogenesis and fatty acid oxidation via the AMPK/Sirt1 pathway.LB100 may be a potential therapeutic agent for NAFLD.

Fat cell-secreted adiponectin mediates physical exercise-induced hippocampal neurogenesis: an alternative anti-depressive treatment?

Psychological depression is drawing accumulating attention nowadays, due to the skyrocketing incidence worldwide and the enormous burdens it incurs. Physical exercise has been long recog- nized for its therapeutic effects on depressive disorders, although knowledge of the underlying mechanisms remains limited. Suppressed hippocampal neurogenesis in adult brains has been regarded, at least partly, contributive to depression, whereas physical exercise that restores neuro- genesis accordingly exerts the anti-depressive action. Several recent publications have suggested the potential role of adiponectin, a protein hormone secreted by peripheral mature adipocytes, in mediating physical exercise-triggered enhancement of hippocampal neurogenesis and alleviation of depression. Here, we briefly review these novel findings and discuss the possibility of counter- acting depression by modulating adiponectin signaling in the hippocampus with interventions including physical exercise and administration of pharmacological agents.