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1.
Life Sci ; 248: 117474, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32112869

RESUMO

BACKGROUND/OBJECTIVES: Nicotinamide N-methyltransferase (NNMT) is a novel regulator of energy homeostasis in adipocytes. NNMT expression in adipose tissue is increased in obesity and diabetes. Knockdown of NNMT prevents mice from developing diet-induced obesity, which is closely linked to insulin resistance. An early sign of systemic insulin resistance is reduced expression of glucose transporter 4 (GLUT4) selectively in adipose tissue. Adipose tissue-specific knockout and overexpression of GLUT4 cause reciprocal changes in NNMT expression. The aim of the current study was to elucidate the mechanism that regulates NNMT expression in adipocytes. METHODS: 3T3-L1 adipocytes were cultured in media with varying glucose concentrations or activators and inhibitors of intracellular pathways. NNMT mRNA and protein levels were measured with quantitative polymerase chain reaction and Western blotting. RESULTS: Glucose deprivation of 3T3-L1 adipocytes induced a 2-fold increase in NNMT mRNA and protein expression. This effect was mimicked by inhibition of glucose transport with phloretin, and by inhibition of glycolysis with the phosphoglucose isomerase inhibitor 2-deoxyglucose. Conversely, inhibition of the pentose phosphate pathway did not affect NNMT expression. Pharmacological activation of the cellular energy sensor AMP-activated protein kinase (AMPK) and inhibition of the mammalian target of rapamycin (mTOR) pathway caused an increase in NNMT levels that was similar to the effect of glucose deprivation. Activation of mTOR with MHY1485 prevented the effect of glucose deprivation on NNMT expression. Furthermore, upregulation of NNMT levels depended on functional autophagy and protein translation. CONCLUSION: Glucose availability regulates NNMT expression via an mTOR-dependent mechanism.


Assuntos
Adipócitos/efeitos dos fármacos , Transportador de Glucose Tipo 4/genética , Glucose/farmacologia , Nicotinamida N-Metiltransferase/genética , Serina-Treonina Quinases TOR/genética , Células 3T3-L1 , Proteínas Quinases Ativadas por AMP/genética , Proteínas Quinases Ativadas por AMP/metabolismo , Adipócitos/citologia , Adipócitos/metabolismo , Animais , Autofagia/efeitos dos fármacos , Autofagia/genética , Transporte Biológico/efeitos dos fármacos , Diferenciação Celular , Desoxiglucose/farmacologia , Metabolismo Energético/genética , Regulação da Expressão Gênica , Glucose/metabolismo , Transportador de Glucose Tipo 4/antagonistas & inibidores , Transportador de Glucose Tipo 4/metabolismo , Glucose-6-Fosfato Isomerase/antagonistas & inibidores , Glucose-6-Fosfato Isomerase/genética , Glucose-6-Fosfato Isomerase/metabolismo , Homeostase/genética , Camundongos , Morfolinas/farmacologia , Nicotinamida N-Metiltransferase/antagonistas & inibidores , Nicotinamida N-Metiltransferase/metabolismo , Via de Pentose Fosfato/efeitos dos fármacos , Via de Pentose Fosfato/genética , Floretina/farmacologia , Biossíntese de Proteínas , RNA Mensageiro/antagonistas & inibidores , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Serina-Treonina Quinases TOR/metabolismo , Triazinas/farmacologia
2.
Gene ; 735: 144404, 2020 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-32018013

RESUMO

Glucose uptake in adipocytes is crucial for regulating systemic metabolism. Long noncoding RNAs (lncRNAs), defined as being transcripts with lengths exceeding 200 nucleotides that are not translated, are recently identified regulators of cellular functions. Previously, we have shown that an lncRNA, "down-regulated expression by hepatitis B virus X" (dreh), is involved in glucose transport in skeletal muscle cells. Here, we aimed to examine the involvement of dreh in glucose transport in 3T3-L1 adipocytes. Expression analysis showed that dreh was expressed in 3T3-L1 fibroblasts and adipocytes. Knockdown of dreh expression using its specific siRNAs lowered the glucose concentration of the medium and facilitated [3H]-2-deoxyglucose transport in adipocytes. Additionally, dreh silencing enhanced the protein expression of glucose transporter (GLUT4) in the plasma membrane of adipocytes. Treatment with siRNA against vimentin attenuated the glucose-lowering effect of dreh depletion. These results suggest that the repression of dreh facilitates glucose transport via increased GLUT4 expression in the plasma membrane through the involvement of vimentin in 3T3-L1 adipocytes. In conclusion, dreh is the first observed lncRNA that regulates glucose transport in adipocytes and could serve as a novel therapeutic target for diabetes by modulating adipocyte function. Considering the new function of dreh, we propose that dreh be renamed "down-regulated expression-related hexose/glucose transport enhancer."


Assuntos
Adipócitos/metabolismo , Transportador de Glucose Tipo 4/metabolismo , Glucose/metabolismo , RNA Longo não Codificante/genética , Vimentina/metabolismo , Animais , Linhagem Celular , Fibroblastos/metabolismo , Camundongos , RNA Longo não Codificante/metabolismo
3.
Nat Commun ; 11(1): 575, 2020 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-31996678

RESUMO

mTORC2 phosphorylates AKT in a hydrophobic motif site that is a biomarker of insulin sensitivity. In brown adipocytes, mTORC2 regulates glucose and lipid metabolism, however the mechanism has been unclear because downstream AKT signaling appears unaffected by mTORC2 loss. Here, by applying immunoblotting, targeted phosphoproteomics and metabolite profiling, we identify ATP-citrate lyase (ACLY) as a distinctly mTORC2-sensitive AKT substrate in brown preadipocytes. mTORC2 appears dispensable for most other AKT actions examined, indicating a previously unappreciated selectivity in mTORC2-AKT signaling. Rescue experiments suggest brown preadipocytes require the mTORC2/AKT/ACLY pathway to induce PPAR-gamma and establish the epigenetic landscape during differentiation. Evidence in mature brown adipocytes also suggests mTORC2 acts through ACLY to increase carbohydrate response element binding protein (ChREBP) activity, histone acetylation, and gluco-lipogenic gene expression. Substrate utilization studies additionally implicate mTORC2 in promoting acetyl-CoA synthesis from acetate through acetyl-CoA synthetase 2 (ACSS2). These data suggest that a principal mTORC2 action is controlling nuclear-cytoplasmic acetyl-CoA synthesis.


Assuntos
ATP Citrato (pro-S)-Liase/metabolismo , Adipócitos Marrons/metabolismo , Lipogênese/fisiologia , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Acetato-CoA Ligase/metabolismo , Animais , Proteínas de Transporte , Epigênese Genética , Ácido Graxo Sintases , Edição de Genes , Expressão Gênica , Transportador de Glucose Tipo 4/genética , Transportador de Glucose Tipo 4/metabolismo , Células HEK293 , Histonas/metabolismo , Humanos , Lipogênese/genética , Camundongos , Camundongos Endogâmicos C57BL , PPAR gama/metabolismo , Fosforilação , Proteômica , Elementos de Resposta
4.
J Clin Endocrinol Metab ; 105(3)2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31606738

RESUMO

CONTEXT: Oncostatin M (OSM) plays a key role in inflammation, but its regulation and function during obesity is not fully understood. OBJECTIVE: The aim of this study was to evaluate the relationship of OSM with the inflammatory state that leads to impaired glucose homeostasis in obesity. We also assessed whether OSM immunoneutralization could revert metabolic disturbances caused by a high-fat diet (HFD) in mice. DESIGN: 28 patients with severe obesity were included and stratified into two groups: (1) glucose levels <100 mg/dL and (2) glucose levels >100 mg/dL. White adipose tissue was obtained to examine OSM gene expression. Human adipocytes were used to evaluate the effect of OSM in the inflammatory response, and HFD-fed C57BL/6J mice were injected with anti-OSM antibody to evaluate its effects. RESULTS: OSM expression was elevated in subcutaneous and visceral fat from patients with obesity and hyperglycemia, and correlated with Glut4 mRNA levels, serum insulin, homeostatic model assessment of insulin resistance, and inflammatory markers. OSM inhibited adipogenesis and induced inflammation in human adipocytes. Finally, OSM receptor knockout mice had increased Glut4 mRNA levels in adipose tissue, and OSM immunoneutralization resulted in a reduction of glucose levels and Ccl2 expression in adipose tissue from HFD-fed mice. CONCLUSIONS: OSM contributes to the inflammatory state during obesity and may be involved in the development of insulin resistance.


Assuntos
Glucose/metabolismo , Homeostase , Obesidade/metabolismo , Oncostatina M/fisiologia , Adipócitos/citologia , Adulto , Animais , Feminino , Transportador de Glucose Tipo 4/genética , Humanos , Resistência à Insulina , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Pessoa de Meia-Idade , Receptores de Oncostatina M/fisiologia
5.
J Endod ; 46(1): 81-88, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31767340

RESUMO

INTRODUCTION: Pulp capping materials allow healing of injured pulp with a layer of reparative dentin. Glucose is needed to cure the injured area. Glucose is transported by glucose transporter (Glut) 2 and Glut4, which are transmembrane proteins that act as gatekeepers. We hypothesized that the transport of glucose via Glut2/Glut4 might contribute to the production of a dentin bridge during wound healing. Therefore, we explored Glut2 and Glut4 expression during reparative dentinogenesis after mineral trioxide aggregate capping. METHODS: The upper left first molar of 8-week-old Wistar rats underwent pulpotomy with mineral trioxide aggregate. At 1, 3, 5, 7, and 14 days after treatment, localization and colocalization of Glut2, Glut4, nestin (odontoblast marker), and antiendothelial cell antigen 1 (RECA-1; endothelial cell marker) were analyzed with immunohistochemical staining. Messenger RNA expression levels of Slc2a2 (encoding Glut2), Slc2a4 (encoding Glut4), Igf-1r (encoding insulinlike growth factor 1 receptor), and nestin were analyzed in the extracted teeth using real-time polymerase chain reaction. RESULTS: Glut2 and Glut4 were localized within odontoblasts and endothelial cells in normal control teeth. Three days after pulpotomy, Glut2- and Glut4-positive cells were detected; 7 days after pulpotomy, immunoreactivity for Glut2 and Glut4 was confined to newly differentiated odontoblastlike cells arranged beneath reparative dentin. Messenger RNA expression levels of Slc2a2 and Slc2a4 were significantly up-regulated after pulpotomy. CONCLUSIONS: Glut2 and Glut4 regulate glucose transport during wound healing beneath the injured area. This may contribute to the development of new vital pulp therapy for patients with deep caries.


Assuntos
Transportador de Glucose Tipo 2 , Transportador de Glucose Tipo 4 , Glucose , Pulpotomia , Cicatrização , Compostos de Alumínio , Animais , Compostos de Cálcio , Polpa Dentária , Capeamento da Polpa Dentária , Combinação de Medicamentos , Células Endoteliais , Glucose/metabolismo , Transportador de Glucose Tipo 2/fisiologia , Transportador de Glucose Tipo 4/fisiologia , Humanos , Dente Molar , Óxidos , Ratos , Ratos Wistar , Silicatos
6.
Toxicol Lett ; 318: 1-11, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31618665

RESUMO

Triptolide (TP), a principal bioactive component extracted from traditional Chinese medicine Tripterygium wilfordii Hook. F. (TWHF), has attracted wide attention of its therapeutic effects on inflammation and autoimmune diseases. However, the therapeutic application of TP is hindered by severe cardiomyocyte toxicity and narrow therapeutic window. We previously identified that the p53 was an indispensable contributor in TP-induced myocardial injury. p53 has an inhibitory effect on IKKß-NF-κB pathway that regulates glucose transporters (GLUT) expression. Based on these evidences, we speculate that p53 mediates TP-disturbed glucose uptake by blocking IKKß-NF-κB signaling. This study focused on the effect of TP on cardiac glucose uptake and the role of p53 in glucose metabolism in cardiomyocytes, and p53 -/- mice. TP treatment depressed glucose consumption and ATP production resulting in myocardial damage. Incubation with ATP (5 mM) remarkably decreased the cellular damage. Immunoblotting and immunofluorescence identified that TP suppressed glucose uptake by restricting IKKß-NF-κB signaling activation, GLUT1 and GLUT4 expression. p53 inhibition alleviated the cell damage and the compromise of glucose uptake. Mechanistically, p53 antagonist PFTα abolished TP-induced the inhibition of IKKß, IκBα phosphorylation, p65 nuclear translocation, and GLUT1, GLUT4 expression. Consistently, in acute heart injury models, p53 deficiency upregulated IKKß-NF-κB activation and GLUT1, GLUT4 protein levels which was also indicated as amelioration of heart histological injury after 1.2 mg kg-1 TP administration. The present findings indicate that TP-induced p53 overactivation suppresses glucose uptake by inhibiting IKKß-NF-κB pathway and downregulating NF-κB-dependent GLUT1 and GLUT4 expression.


Assuntos
Diterpenos/toxicidade , Glucose/metabolismo , Cardiopatias/induzido quimicamente , Quinase I-kappa B/metabolismo , Miócitos Cardíacos/efeitos dos fármacos , NF-kappa B/metabolismo , Fenantrenos/toxicidade , Proteína Supressora de Tumor p53/metabolismo , Animais , Apoptose/efeitos dos fármacos , Cardiotoxicidade , Linhagem Celular , Metabolismo Energético/efeitos dos fármacos , Compostos de Epóxi/toxicidade , Transportador de Glucose Tipo 1/genética , Transportador de Glucose Tipo 1/metabolismo , Transportador de Glucose Tipo 4/genética , Transportador de Glucose Tipo 4/metabolismo , Cardiopatias/genética , Cardiopatias/metabolismo , Cardiopatias/patologia , Camundongos Knockout , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , Ratos Sprague-Dawley , Transdução de Sinais/efeitos dos fármacos , Proteína Supressora de Tumor p53/deficiência , Proteína Supressora de Tumor p53/genética
7.
Food Funct ; 10(11): 7216-7226, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31612177

RESUMO

Offspring of dams exposed to excess folic acid during the perigestational period have been shown by us to be predisposed to metabolic dysfunction revealed by hyperglycemia, glucose intolerance, increased insulin and decreased adiponectin in late adulthood. This work aims to characterize adipocyte phenotype and expression profile of genes in the regulation of lipid and glucose metabolism in visceral adipose tissue and in skeletal muscle. From mating until weaning, a recommended dose of folic acid for pregnancy (C, 2 mg of folic acid per kg of diet) or a high folic acid dose (HFA, 40 mg of folic acid per kg of diet) was administered to Sprague-Dawley females. At 10 months of age progeny were divided into groups fed the standard chow (C/STD and HFA/STD) and groups fed the standard chow plus drinking water with 10% fructose (C/FRU and HFA/FRU), as an additional metabolic challenge. Adipocyte morphology and quantification of key genes involved in lipid and glucose metabolism were studied in visceral adipose tissue and skeletal muscle of 13 months old offspring. HFA exposure led to an enlargement of visceral adipose cells most likely mediated by an upregulation of lipoprotein lipase, and it tended to downregulate Glut4 in visceral adipose tissue and skeletal muscle. Fructose exposure in a background of perigestational excess folic acid, but not in controls, induced an upregulation of lipogenesis pathway genes and it decreased jejunal expression of the proton-coupled folate transporter (Pcft1). In addition, fructose exposure led to a downregulation of jejunal Sglt1 in control animals. Our data suggest that high folic acid exposure during the perigestational period caused morphologic and genic alterations related to insulin resistant states indicating that this intervention may act as an effective programmer of long-term metabolic dysfunction.


Assuntos
Suplementos Nutricionais/efeitos adversos , Ácido Fólico/efeitos adversos , Doenças Metabólicas/etiologia , Efeitos Tardios da Exposição Pré-Natal/etiologia , Animais , Suplementos Nutricionais/análise , Feminino , Ácido Fólico/administração & dosagem , Transportador de Glucose Tipo 4/genética , Transportador de Glucose Tipo 4/metabolismo , Resistência à Insulina , Gordura Intra-Abdominal/metabolismo , Masculino , Fenômenos Fisiológicos da Nutrição Materna , Doenças Metabólicas/genética , Doenças Metabólicas/metabolismo , Músculo Esquelético/metabolismo , Gravidez , Efeitos Tardios da Exposição Pré-Natal/genética , Efeitos Tardios da Exposição Pré-Natal/metabolismo , Transportador de Folato Acoplado a Próton/genética , Transportador de Folato Acoplado a Próton/metabolismo , Ratos , Ratos Sprague-Dawley
8.
Life Sci ; 239: 116897, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31644894

RESUMO

AIMS: Lansoprazole (LPZ) is one of the most commonly prescribed drugs for treatment of acid-related diseases, and it is increasingly recognized for its potential application as an anti-diabetic therapy. Although LPZ target tissues remain poorly understood, possible sites of action include adipose tissue. In this study, we assessed effects of LPZ on adipocyte differentiation and function by using 3T3-L1 preadipocytes and HFD-induced obesity mice as an in vitro and in vivo model, respectively. MAIN METHODS: Oil red O staining and intracellular triacylglycerol content were used to determine lipid accumulation. Glucose uptake was performed to measure mature adipocyte function. Expression of adipocyte genes was determined by qRT-PCR and immunoblotting. KEY FINDINGS: LPZ has dual effects on differentiation of 3T3-L1 cells. At low concentrations, LPZ enhanced adipocyte differentiation via induction of PPARγ and C/EBPα, two master adipogenic transcription factors, as well as lipogenic proteins, ACC1 and FASN. Increasing of adipocyte number subsequently increased basal and insulin-stimulated glucose uptake, and expression of Glut4 mRNA. Conversely, high concentrations of LPZ strongly inhibited differentiation and expression of PPARγ and C/EBPα, and maintained expression of preadipocytes markers, ß-catenin and Pref-1. Inhibition of adipogenesis by LPZ reduced mature adipocyte number, Glut4 mRNA expression and insulin-stimulated glucose uptake. In addition, treatment with LPZ at 200 mg/kg significantly reduced body weight gain and total fat mass in HFD-induced obese mice. SIGNIFICANCE: These results indicate that effects of LPZ on adipocyte differentiation are dependent on concentration and are correlated with PPARγ and C/EBPα.


Assuntos
Adipócitos/efeitos dos fármacos , Adipócitos/metabolismo , Lansoprazol/metabolismo , Células 3T3-L1 , Adipócitos/fisiologia , Adipogenia/efeitos dos fármacos , Animais , Proteína alfa Estimuladora de Ligação a CCAAT/metabolismo , Diferenciação Celular/efeitos dos fármacos , Dieta Hiperlipídica , Transportador de Glucose Tipo 4/metabolismo , Insulina/metabolismo , Lansoprazol/farmacologia , Metabolismo dos Lipídeos/efeitos dos fármacos , Lipogênese , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Obesidade/metabolismo , PPAR gama/metabolismo , Triglicerídeos/metabolismo
9.
Nat Commun ; 10(1): 4623, 2019 10 11.
Artigo em Inglês | MEDLINE | ID: mdl-31604916

RESUMO

Reactive oxygen species (ROS) act as intracellular compartmentalized second messengers, mediating metabolic stress-adaptation. In skeletal muscle fibers, ROS have been suggested to stimulate glucose transporter 4 (GLUT4)-dependent glucose transport during artificially evoked contraction ex vivo, but whether myocellular ROS production is stimulated by in vivo exercise to control metabolism is unclear. Here, we combined exercise in humans and mice with fluorescent dyes, genetically-encoded biosensors, and NADPH oxidase 2 (NOX2) loss-of-function models to demonstrate that NOX2 is the main source of cytosolic ROS during moderate-intensity exercise in skeletal muscle. Furthermore, two NOX2 loss-of-function mouse models lacking either p47phox or Rac1 presented striking phenotypic similarities, including greatly reduced exercise-stimulated glucose uptake and GLUT4 translocation. These findings indicate that NOX2 is a major myocellular ROS source, regulating glucose transport capacity during moderate-intensity exercise.


Assuntos
Citosol/metabolismo , Glucose/metabolismo , Músculo Esquelético/metabolismo , NADPH Oxidase 2/metabolismo , Esforço Físico , Espécies Reativas de Oxigênio/metabolismo , Adulto , Animais , Ergometria , Transportador de Glucose Tipo 4/metabolismo , Humanos , Masculino , Camundongos , Músculo Esquelético/citologia , Oxirredução , Fosforilação , Condicionamento Físico Animal , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo
10.
Life Sci ; 236: 116906, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31614147

RESUMO

AIMS: The anti-hyperglycemic action of metformin on skeletal muscles is presently unclear. Long noncoding RNAs (lncRNAs) are implicated in multiple cellular functions. This study aims to explore the role of lncRNAs in the glucometabolic action of metformin on skeletal muscle cells. MAIN METHODS: Metformin accumulation was assessed using [14C]-metformin. A lncRNA array was used to investigate metformin-regulated lncRNAs in C2C12 skeletal muscle cells. Knockdown studies were applied to evaluate the function of lncRNA Dreh. A colorimetric assay was used for the measurement of medium glucose concentration; glucose transport was assessed using [3H]-2-deoxyglucose; real-time PCR was used for RNA expression analysis, and western blotting was used to assess protein expression in myotubes. A Dreh overexpression plasmid was transfected into the cells. KEY FINDINGS: Metformin accumulated in C2C12 myotubes. Metformin reduced medium glucose concentration and repressed lncRNA Dreh expression in the myotubes. Knockdown of Dreh in the myotubes resulted in reduced glucose concentration in the culture medium, increased glucose transport, and increased levels of GLUT4 protein in the plasma membrane. Overexpression of Dreh attenuated the glucose-lowering effect of metformin in myotubes. SIGNIFICANCE: The glucoregulatory actions of metformin are mediated in part by a lncRNA, Dreh, in the skeletal muscle cells. Dreh is a novel regulator for glucose transport and could be a therapeutic target for diabetes.


Assuntos
Glucose/metabolismo , Hipoglicemiantes/farmacologia , Metformina/farmacologia , Fibras Musculares Esqueléticas/metabolismo , Músculo Esquelético/metabolismo , RNA Longo não Codificante/genética , Animais , Transporte Biológico , Linhagem Celular , Regulação da Expressão Gênica , Transportador de Glucose Tipo 4/genética , Transportador de Glucose Tipo 4/metabolismo , Camundongos , Fibras Musculares Esqueléticas/citologia , Fibras Musculares Esqueléticas/efeitos dos fármacos , Músculo Esquelético/citologia , Músculo Esquelético/efeitos dos fármacos
11.
Int J Mol Med ; 44(3): 1161-1171, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31524229

RESUMO

The present study investigated whether glucagon like peptide­1 (GLP­1) improves glucose uptake through glucose transporter type 4 (GLUT4), mediated by the activation of sirtuin 1 (SIRT1), in skeletal muscle cells with palmitate induced­insulin resistance. The levels of glucose uptake, GLUT4, protein kinase A (PKA), and cyclic adenosine monophosphate (cAMP) were determined in human skeletal muscle myotubes (HSMMs) exposed to palmitate and GLP­1. Then, to determine whether PKA/cAMP were downstream signals of GLP­1, a PKA inhibitor was used. To determine whether SIRT­1 contributes to GLP­1 action in HSMMs with palmitate­induced insulin resistance, the levels of peroxisome proliferator­activated receptor γ coactivator 1α (PGC1α) deacetylation and SIRT­1 activity were assessed using a SIRT1 inhibitor and small interfering RNA (siRNA). The phosphorylation levels of protein kinase B (Akt) and insulin receptor substrate 1 (IRS­1) as insulin signaling pathways, were assessed in GLP­1­treated HSMMs exposed to palmitate. The influence of SIRT1 on the GLP­1­induced activation of insulin signaling pathway was determined using a SIRT1 inhibitor. GLP­1 restored the palmitate­induced reductions in the levels of glucose uptake, GLUT4 mRNA, GLUT4 promoter activity, and GLUT4 protein in HSMMs. PKA and cAMP, as GLP­1 downstream signals, played a role in this process. GLP­1 increased the deacetylation levels of PGC1α, and stimulated SIRT1 in HSMMs. Moreover, the SIRT1 inhibitor and siRNA of SIRT1 suppressed the effect of GLP­1 on GLUT4 expression in HSMMs exposed to palmitate. The SIRT1 inhibitor also prevented the GLP­1­induced phosphorylation of IRS­1 and Akt in palmitate­treated HSMMs. The present findings suggest that in palmitate­induced insulin­resistant HSMM, GLP­1 activates SIRT1 through the PKA/cAMP pathway, which in turn enhances glucose uptake through GLUT4 and the insulin signaling pathway.


Assuntos
Peptídeo 1 Semelhante ao Glucagon/farmacologia , Resistência à Insulina , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismo , Ácido Palmítico/farmacologia , Sirtuína 1/metabolismo , Acetilação , Ativação Enzimática , Transportador de Glucose Tipo 4/genética , Transportador de Glucose Tipo 4/metabolismo , Humanos , Modelos Biológicos , Fosforilação , Proteínas Recombinantes/farmacologia , Transdução de Sinais/efeitos dos fármacos
12.
Int J Mol Sci ; 20(19)2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31557807

RESUMO

EPA, an omega-3 polyunsaturated fatty acid, exerts beneficial effects on human health. However, the molecular mechanisms underlying EPA function are poorly understood. The object was to illuminate molecular mechanism underlying EPA's role. Here, 1H-NMR-based metabolic analysis showed enhanced branched-chain amino acids (BCAAs) and lactate following EPA treatment in skeletal muscle cells. EPA regulated mitochondrial oxygen consumption rate. Furthermore, EPA induced calcium/calmodulin-dependent protein kinase kinase (CaMKK) through the generation of intracellular calcium. This induced the phosphorylation of AMP-activated protein kinase (AMPK) and p38 mitogen-activated protein kinase (p38 MAPK) that led to glucose uptake, and the translocation of glucose transporter type 4 (GLUT4) in muscles. In conclusion, EPA exerts benign effects on glucose through the activation of AMPK-p38 MAPK signaling pathways in skeletal muscles.


Assuntos
Ácido Eicosapentaenoico/farmacologia , Glucose/metabolismo , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Redes e Vias Metabólicas/efeitos dos fármacos , Monofosfato de Adenosina/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Cálcio/metabolismo , Metabolismo dos Carboidratos/efeitos dos fármacos , Regulação da Expressão Gênica , Transportador de Glucose Tipo 4/genética , Transportador de Glucose Tipo 4/metabolismo , Camundongos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismo , Mioblastos/efeitos dos fármacos , Mioblastos/metabolismo , Consumo de Oxigênio/efeitos dos fármacos
13.
Life Sci ; 236: 116836, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31493479

RESUMO

AIMS: The present experiment was conceptualised to explore the therapeutic response of tetramethylpyrazine (TMP), a major active constituent of Ligusticum chuanxiong, a Chinese traditional medicinal plant, in high-fat diet (HFD)-streptozotocin (STZ)-induced diabetes in rats and to identify the possible mechanism of action. MAIN METHODS: Dose-reliant effect of oral treatment of TMP (100, 150 and 200 mg/kg/day) for 28 days was evaluated by calculating the alteration in body weight, level of fasting blood glucose (FBG), plasma insulin, homeostasis model assessment (HOMA), serum lipids, oral glucose & intraperitoneal insulin tolerance and glycosylated haemoglobin in HFD-STZ-induced type-2 diabetic (T2D) rats and underlying molecular mechanisms of TMP was also studied. KEY FINDINGS: TMP treatment prominently reduced the level of FBG, glycosylated haemoglobin and revived body weight gain and level of serum insulin dose-dependently in diabetic rats. TMP treatment considerably improved insulin resistance, as observed in oral glucose tolerance and insulin tolerance tests. Moreover, dose-dependent reduction in the level of pro-inflammatory cytokines, C-reactive protein (CRP) and interleukin-6 (IL-6) was observed and their level was found to be significantly reduced in highest dose TMP (200 mg/kg) treated diabetic rats, pointing towards TMP mediated recovery of insulin signalling and a decrease in insulin resistance. The expressions of p-PI3K-p85/p-Akt/GLUT-4 were also significantly up-regulated by TMP (200 mg/kg), suggesting the connection of the PI3K/Akt signal pathway in the anti-hyperglycemic action of TMP. SIGNIFICANCE: These findings suggest that TMP may be used as a potential agent for type-2 diabetes treatment.


Assuntos
Diabetes Mellitus Experimental/prevenção & controle , Diabetes Mellitus Tipo 2/prevenção & controle , Regulação da Expressão Gênica/efeitos dos fármacos , Transportador de Glucose Tipo 4/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Pirazinas/farmacologia , Animais , Glicemia , Diabetes Mellitus Experimental/etiologia , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/patologia , Diabetes Mellitus Tipo 2/etiologia , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patologia , Dieta Hiperlipídica/efeitos adversos , Modelos Animais de Doenças , Transportador de Glucose Tipo 4/genética , Masculino , Fosfatidilinositol 3-Quinases/genética , Proteínas Proto-Oncogênicas c-akt/genética , Ratos , Ratos Wistar , Transdução de Sinais , Vasodilatadores/farmacologia
14.
J Biol Regul Homeost Agents ; 33(5): 1327-1335, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31487982

RESUMO

The glucose transporter 4 (GLUT4) translocation is a vital link of insulin-induced glucose uptake in adipose tissue and skeletal muscle. It is an important topic in anti-diabetic research to explore novel agents to facilitate the role of insulin. The aim of this study was to verify the hypothesis that neuropeptide galanin may enhance insulin-induced GLUT4 translocation to increase glucose uptake in adipose tissue of type 2 diabetic models. Insulin and/or galanin were injected respectively or cooperatively into type 2 diabetic rats once a day for fifteen days. The results showed that administration of galanin significantly enhanced insulin-induced GLUT4 and vesicle-associated membrane protein 2 (VAMP2) translocation, Akt phosphorylation and glucose uptake, but not GLUT4 mRNA and protein expression levels in adipose cells. The beneficial roles of galanin on insulin-induced events may be blocked by MK-2206, an Akt inhibitor, indicating that the Akt phosphorylation is essential for promoting impact of galanin on the insulin-induced events. These results suggest that galanin may benefit insulin-induced GLUT4 and VAMP2 translocation, and subsequent glucose uptake via the activated Akt-VAMP2-GLUT4 pathway in adipose cells. These findings deepen our understanding of the anti-diabetic effect of galanin and its mechanism.


Assuntos
Adipócitos/metabolismo , Diabetes Mellitus Experimental/tratamento farmacológico , Galanina/farmacologia , Transportador de Glucose Tipo 4/metabolismo , Insulina/farmacologia , Animais , Diabetes Mellitus Experimental/metabolismo , Glucose/metabolismo , Transporte Proteico , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ratos , Proteína 2 Associada à Membrana da Vesícula/metabolismo
15.
Life Sci ; 234: 116734, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31394126

RESUMO

AIMS: Acute myocardial insulin resistance is an independent risk factor for patients who undergo cardiac surgery with cardiopulmonary bypass (CPB). However, the underlying mechanism of insulin resistance during CPB has not been fully investigated. MATERIALS AND METHODS: To explore the role of myocardial insulin resistance on the cardiac function and its underlying mechanism, CPB operation and pharmacological intervention were applied in mini pigs, and myocardial insulin signaling, glucose uptake, ATP production and cardiac function were examined. KEY FINDINGS: Our data showed that CPB elicited not only hyperglycemia and hyperinsulinemia, but also inactivated Akt, and impaired the transposition of membrane glucose transporter-4 (GLUT-4), reduced glucose uptake and ATP production in the myocardium as well, which in turn was accompanied with cardiac dysfunction. Meanwhile, linear correlations were established among reduced myocardial glucose uptake, ATP production, and depressed cardiac systolic or diastolic function. Reactivation of Akt by SC79, an Akt agonist, partially alleviated myocardial insulin resistance and restored post CPB cardiac function via augmenting myocardial glucose uptake and ATP production. SIGNIFICANCE: These findings revealed that acute myocardial insulin resistance due to inactivation of Akt played a key role in cardiac dysfunction post CPB via suppressing glucose metabolism related energy supply.


Assuntos
Ponte Cardiopulmonar/efeitos adversos , Resistência à Insulina , Insulina/metabolismo , Miocárdio/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Glucose/metabolismo , Transportador de Glucose Tipo 4/metabolismo , Coração/fisiopatologia , Masculino , Miocárdio/patologia , Suínos , Porco Miniatura
16.
Nutrients ; 11(8)2019 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-31394876

RESUMO

Oleacein is one of the most abundant polyphenolic compounds of olive oil, which has been shown to play a protective role against several metabolic abnormalities, including dyslipidemia, insulin resistance, and glucose intolerance. Herein, we investigated the effects of oleacein on certain markers of adipogenesis and insulin-resistance in vitro, in 3T3-L1 adipocytes, and in vivo in high-fat diet (HFD)-fed mice. During the differentiation process of 3T3-L1 preadipocytes into adipocytes, oleacein strongly inhibited lipid accumulation, and decreased protein levels of peroxisome proliferator-activated receptor gamma (PPARγ) and fatty acid synthase (FAS), while increasing Adiponectin levels. In vivo, treatment with oleacein of C57BL/6JOlaHsd mice fed with HFD for 5 and 13 weeks prevented the increase in adipocyte size and reduced the inflammatory infiltration of macrophages and lymphocytes in adipose tissue. These effects were accompanied by changes in the expression of adipose tissue-specific regulatory elements such as PPARγ, FAS, sterol regulatory element-binding transcription factor-1 (SREBP-1), and Adiponectin, while the expression of insulin-sensitive muscle/fat glucose transporter Glut-4 was restored in HFD-fed mice treated with oleacein. Collectively, our findings indicate that protection against HFD-induced adiposity by oleacein in mice is mediated by the modulation of regulators of adipogenesis. Protection against HFD-induced obesity is effective in improving peripheral insulin sensitivity.


Assuntos
Adiposidade/efeitos dos fármacos , Aldeídos/farmacologia , Dieta Hiperlipídica , Resistência à Insulina , Fenóis/farmacologia , Células 3T3-L1 , Adipogenia/efeitos dos fármacos , Tecido Adiposo/química , Tecido Adiposo/efeitos dos fármacos , Animais , Fármacos Antiobesidade/farmacologia , Biomarcadores/análise , Transportador de Glucose Tipo 4/análise , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Obesidade/prevenção & controle
17.
Biomed Res Int ; 2019: 3719643, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31467885

RESUMO

Background: The clinical anti-inflammatory drug dexamethasone (DEX) can cause many side effects such as muscle atrophy for long-term use. Muscle atrophy induced by DEX may be caused by decrease of glucose consumption. Panax ginseng C.A. Meyer was previously considered to be an antiatrophic agent for glucocorticoid- (GC-) treated therapies. As one of the main components, it remains unclear whether ginseng total protein (GP) facilitates recovery from muscle atrophy induced by DEX. Methods: In this study, GP was extracted and purified with Sephadex-G50. C2C12 myoblasts was induced with 2% horse serum to differentiate into C2C12 myotubes. Cell viability was analyzed by the MTT assay, and Ca2+ concentration was analyzed by a flow cytometer. The release of lactic dehydrogenase (LDH) and the glucose consumption were analyzed by spectrophotometry. The phosphorylation of AMP-activated protein kinase (AMPK), phosphoinositide 3-kinase (PI3K), and protein kinase B (Akt) and the expression of glucose transporter 4 (GLUT4) were analyzed by Western blotting. The phosphorylation of AS160 was quantified by Immunofluorescence staining. Results: We found that GP increased cell viability and increased myotube diameter in high-dose DEX-treated C2C12 myotubes for 24 h, but this activity was not found in the enzymatic hydrolyzed GP group. GP reduced muscle atrophy by decreasing the expression of key proteins such as muscle RING-finger protein-1 and muscle atrophy F-box, reducing the Ca2+ concentration, and decreasing the release of LDH in DEX-injured C2C12 myotubes. Moreover, GP improved glucose consumption and increased the phosphorylation of AMPK, PI3K, Akt, and AS160 and the expression of GLUT4 in DEX-treated C2C12 myotubes. Conclusion: The results of this study suggest that GP has effects on recovering DEX-induced muscle atrophy and cell injury, which may improve glucose consumption via the AMPK and PI3K/Akt pathways in high-dose DEX-treated C2C12 myotubes. This study provides in vitro mechanistic insights into the recovery of muscle atrophy with GP treatment.


Assuntos
Glucose/metabolismo , Atrofia Muscular/tratamento farmacológico , Panax/química , Extratos Vegetais/farmacologia , Animais , Dexametasona/toxicidade , Expressão Gênica/efeitos dos fármacos , Transportador de Glucose Tipo 4 , Humanos , Camundongos , Fibras Musculares Esqueléticas/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/patologia , Atrofia Muscular/induzido quimicamente , Atrofia Muscular/patologia , Mioblastos/efeitos dos fármacos , Mioblastos/patologia , Fosforilação/efeitos dos fármacos , Extratos Vegetais/química
18.
Biomed Pharmacother ; 118: 109297, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31404771

RESUMO

Our study was conducted to investigate the effects of the fruits of Lycium chinense Mill. (Lycii Fructus, LF) and its bioactive compound, betaine, on muscle differentiation and mitochondrial biogenesis in C2C12 cells. LF extract and betaine was analyzed by high-performance liquid chromatography (HPLC). The expression of myosin heavy chain (MyHC) and peroxisome proliferator-activated receptor gamma coactivator1-alpha (PGC-1α), sirtuin-1(Sirt-1), nuclear respiratory factor-1 (NRF-1), transcription factor A, mitochondrial (TFAM) and the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC), were determined in cellular or mitochondrial levels by quantitative polymerase chain reaction (qPCR) or Western blot, respectively. The glucose levels and total ATP contents were measured by the glucose consumption in a culture medium, cellular glucose uptake and ATP assays. LF extract at 4 mg/ml and betaine at 2 and 5 mM significantly increased the expression of MyHC in C2C12 myotubes, compared with non-treated cells. LF extract and betaine significantly increased the expression of PGC-1α, Sirt-1, NRF-1 and TFAM mRNA and protein in the myotubes, as well as phosphorylation of AMPK and ACC. Furthermore, LF extract and betaine significantly increased the mitochondrial protein contents, as the TFAM and NRF-1 expressions were increased. LF extract and betaine also significantly increased the glucose uptake and ATP contents in the myotubes. The LF extract contained 3.18% betaine was quantitated by HPLC. LF extract and betaine enhanced muscle differentiation and energy metabolism through the up-regulation of mitochondrial biogenesis-regulating factors, suggesting that LF extract and betaine can help to prevent the dysfunction of skeletal muscle.


Assuntos
Betaína/farmacologia , Diferenciação Celular/efeitos dos fármacos , Frutas/química , Lycium/química , Mitocôndrias/metabolismo , Músculo Esquelético/citologia , Biogênese de Organelas , Extratos Vegetais/farmacologia , Proteínas Quinases Ativadas por AMP/metabolismo , Animais , Linhagem Celular , Metabolismo Energético/efeitos dos fármacos , Glucose/metabolismo , Transportador de Glucose Tipo 4/metabolismo , Camundongos , Mitocôndrias/efeitos dos fármacos , Proteínas Mitocondriais/metabolismo , Fibras Musculares Esqueléticas/citologia , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fosforilação/efeitos dos fármacos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Transdução de Sinais/efeitos dos fármacos
19.
Cells ; 8(7)2019 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-31266232

RESUMO

BACKGROUND: The zinc transporter Zip7 modulates zinc flux and controls cell signaling molecules associated with glucose metabolism in skeletal muscle. The present study evaluated the role of Zip7 in cell signaling pathways involved in insulin-resistant skeletal muscle and mice fed a high-fat diet. METHODS: Insulin-resistant skeletal muscle cells were prepared by treatment with an inhibitor of the insulin receptor, HNMPA-(AM)3 or palmitate, and Zip7 was analyzed along with pAkt, pTyrosine and Glut4. Similarly, mice fed normal chow (NC) or a high-fat diet (HFD) were also analyzed for protein expression of Glut4 and Zip7. An overexpression system for Zip7 was utilized to determine the action of this zinc transporter on several genes implicated in insulin signaling and glucose control. RESULTS: We identified that Zip7 is upregulated by glucose in normal skeletal muscle cells and downregulated in insulin-resistant skeletal muscle. We also observed (as expected) a decrease in pAkt and Glut4 in the insulin-resistant skeletal muscle cells. The overexpression of Zip7 in skeletal muscle cells led to the modulation of key genes involved in the insulin signaling axis and glucose metabolism including Akt3, Dok2, Fos, Hras, Kras, Nos2, Pck2, and Pparg. In an in vivo mouse model, we identified a reduction in Glut4 and Zip7 in the skeletal muscle of mice fed a HFD compared to NC controls. CONCLUSIONS: These data suggest that Zip7 plays a role in skeletal muscle insulin signaling and is downregulated in an insulin-resistant, and HFD state. Understanding the molecular mechanisms of Zip7 action will provide novel opportunities to target this transporter therapeutically for the treatment of insulin resistance and type 2 diabetes.


Assuntos
Proteínas de Transporte de Cátions/metabolismo , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Resistência à Insulina , Fibras Musculares Esqueléticas/patologia , Animais , Linhagem Celular , Diabetes Mellitus Experimental/etiologia , Diabetes Mellitus Experimental/patologia , Diabetes Mellitus Tipo 2/etiologia , Diabetes Mellitus Tipo 2/patologia , Dieta Hiperlipídica/efeitos adversos , Regulação para Baixo , Glucose/metabolismo , Transportador de Glucose Tipo 4/metabolismo , Insulina/metabolismo , Camundongos , Transdução de Sinais
20.
J Anim Sci ; 97(9): 3907-3919, 2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31294448

RESUMO

The objective of this present study was to determine the effects of phytase dosing on growth performance, mineral digestibility, phytate breakdown, and the level of glucose transporter type 4 (GLUT4) in muscle plasma membranes of weanling pigs. A total of 160 barrows were used in a randomized completely block design and assigned to 4 treatments for a 7-wk study. Depending on the feeding phase, diets differed in dietary calcium (Ca) and phosphorus (P) levels (positive control [PC]: 8 to 6.8g/kg Ca; 7.3 to 6.3 g/kg P; negative control [NC]: 5.5 to 5.2 g/kg Ca; 5.4 to 4.7 g/kg P). NC diets were supplemented with phytase at 0 (NC); 500 (NC + 500 FTU); or 2,000 FTU/kg (NC + 2,000 FTU) phytase units/kg. Blood was collected after fasting (day 48) or feeding (day 49) for measurement of plasma inositol concentrations. On day 49, 2 pigs per pen were euthanized, and duodenal and ileal digesta samples were collected to determine inositol phosphates (InsP6-2) concentrations. High phytase supplementation increased BW on days 21, 35, and 49 (P < 0.05). Over the entire feeding period, ADG, ADFI, and feed efficiency were increased by NC + 2,000 FTU compared with the other treatments (P < 0.05). Postprandial plasma inositol concentration was increased in NC + 2,000 (P < 0.01), but there was only a tendency (P = 0.06) of a higher fasting plasma inositol concentration in this group. Inositol concentrations in the portal vein plasma (day 49) were not different among treatments. Duodenal digesta InsP5 and InsP6 concentrations were similar in PC and NC, but higher in these 2 treatments (P < 0.05) than those supplemented with phytase. Phytase supplementation decreased InsP6-4, resulting in increased InsP3-2 and myo-inositol concentrations. Similar effects were found in ileal contents. Compared with NC, phytase supplementation resulted in greater cumulative InsP6-2 disappearance (93.6% vs. 72.8% vs. 25.0%, for NC + 2,000 FTU, NC + 500 FTU and NC, respectively, P < 0.01) till the distal ileum. Longissimus dorsi muscle plasma membrane GLUT4 concentration was increased by NC + 2,000 FTU (P < 0.01) compared with NC. In summary, high phytase supplementation increased growth performance of nursery pigs. The higher myo-inositol release from phytate could contribute to the increased expression of GLUT4 in muscle plasma membranes. Further investigation is needed to determine whether this is associated with enhanced cellular glucose uptake and utilization.


Assuntos
6-Fitase/administração & dosagem , Suplementos Nutricionais/análise , Transportador de Glucose Tipo 4/metabolismo , Inositol/sangue , Ácido Fítico/metabolismo , Suínos/crescimento & desenvolvimento , Ração Animal/análise , Animais , Cálcio na Dieta/metabolismo , Membrana Celular/metabolismo , Dieta/veterinária , Íleo/metabolismo , Fosfatos de Inositol/metabolismo , Masculino , Músculos/metabolismo , Fósforo na Dieta/metabolismo , Suínos/fisiologia
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