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1.
Cancer Biomark ; 17(1): 41-7, 2016 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-27314291

RESUMO

Salidroside has been reported to exhibit anticancer properties. This study aimed to investigate the effects of salidroside on renal cell carcinoma growth. Cell viability and proliferation was assessed by Cell Counting Kit-8 and colony formation assays in A498 and 786-0 cells. The effects of salidroside on in vivo tumor growth were also assessed in a mouse xenograft model of renal cell carcinoma. Flow cytometry was used to analyze cell cycle and apoptosis and protein levels were determined by western blotting. Salidroside reduced cell viability and colony formation in both cell lines in a concentration- and time-dependent manner. Tumor growth was also suppressed in the mouse model. Furthermore, salidroside induced significant G1 phase cell cycle arrest and induced apoptosis in both A498 and 786-0 cells. Higher concentrations of salidroside reduced the levels of phosphorylated signal transducer and activator of transcription 3 (STAT3) and Janus kinase 2 (JAK2). These results suggested that salidroside produced potent anticancer properties in renal cell carcinoma by modulating JAK2/STAT3 signaling. Administration of salidroside to patients with renal cell carcinoma might provide a promising therapeutic strategy for this malignancy.


Assuntos
Carcinoma de Células Renais/metabolismo , Glucosídeos/farmacologia , Janus Quinase 2/metabolismo , Neoplasias Renais/metabolismo , Fenóis/farmacologia , Fator de Transcrição STAT3/metabolismo , Transdução de Sinais/efeitos dos fármacos , Animais , Apoptose/efeitos dos fármacos , Carcinoma de Células Renais/tratamento farmacológico , Carcinoma de Células Renais/patologia , Caspase 3/metabolismo , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Modelos Animais de Doenças , Humanos , Neoplasias Renais/tratamento farmacológico , Neoplasias Renais/patologia , Masculino , Camundongos , Ensaios Antitumorais Modelo de Xenoenxerto
2.
Arch Anim Nutr ; 70(4): 249-62, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27216553

RESUMO

The contradiction between high susceptibility of early weaned piglets to enteric pathogens and rigid restriction of antibiotic use in the diet is still prominent in the livestock production industry. To address this issue, the study was designed to replace dietary antibiotics partly or completely by an immunostimulant, namely heat-killed Mycobacterium phlei (M. phlei). Piglets (n = 192) were randomly assigned to one of the four groups: (1) basal diet (Group A), (2) basal diet + a mixture of antibiotics (80 mg/kg diet, Group B), (3) basal diet + a mixture of antibiotics (same as in Group B, but 40 mg/kg diet) + heat-killed M. phlei (1.5 g/kg diet) (Group C) and (4) basal diet + heat-killed M. phlei (3 g/kg diet) (Group D). All piglets received the respective diets from days 21 to 51 of age and were weaned at the age of 28 d. Compared with the Control (Group A), in all other groups the average daily gain, average daily feed intake, small intestinal villus height:crypt depth ratio and protein levels of occludin and ZO-1 in the jejunal mucosa were increased. A decreased incidence of diarrhoea in conjunction with an increased sIgA concentration in the intestinal mucosa and serum IL-12 and IFN-γ concentrations was found in groups supplemented with heat-killed M. phlei (Groups C and D), but not in Group B. Groups C and D also showed decreased IL-2 concentrations in the intestinal mucosa with lower TLR4 and phosphor-IκB protein levels. The antioxidant capacity was reinforced in Groups C and D, as evidenced by the reduction in malondialdehyde and enhanced activities of antioxidant enzymes in serum. These data indicate that heat-killed M. phlei is a promising alternative to antibiotic use for early weaned piglets via induction of protective immune responses.


Assuntos
Adjuvantes Imunológicos/administração & dosagem , Dieta/veterinária , Imunidade Inata/efeitos dos fármacos , Imunidade nas Mucosas/efeitos dos fármacos , Mycobacterium phlei/química , Sus scrofa/fisiologia , Ração Animal/análise , Animais , Antioxidantes/metabolismo , Suplementos Nutricionais/análise , Relação Dose-Resposta Imunológica , Metabolismo Energético , Temperatura Alta , Imunomodulação , Intestino Delgado/anatomia & histologia , Intestino Delgado/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Distribuição Aleatória , Sus scrofa/crescimento & desenvolvimento , Sus scrofa/imunologia , Desmame
3.
Ying Yong Sheng Tai Xue Bao ; 26(1): 113-21, 2015 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-25985661

RESUMO

In order to investigate the effects of different irrigation and fertilization on soil microbial properties of summer maize field, we used ZN99 with high nitrogen use efficiency as the test material. The experiment adopted the split plot design which included two irrigation levels (526 mm and 263 mm) as the main plots, three fertilizer types (U, M, UM) and two fertilizer levels (N 100 kg . hm-2 and 200 kg . hm-2) as the subplots. The results showed that the irrigation level affected the regulating effects of fertilizer on soil microbial biomass (carbon and nitrogen) and microbial di- versity. The organic fertilizer application must be under the sufficient irrigation level to increase the soil MBC (14.3%-33.6%), MBN (1.8-2.3 times) and abundance significantly. A moderate rate of irrigation, higher rates of organic fertilizer application or organic manure combined with inorganic fertilizer could increase the nitrogen-fixation species and quantity of Firmicutes, γ-Proteobacteria and α-Proteobacteria in the soil. Under the same N level, there was no significant difference of grain yield between organic manure and inorganic fertilizer treatments. Considering sustainable production, proper organic manure application with moderate irrigation could increase the quantity of the soil microbial biomass and microbial diversity, and improve the capacity of soil to supply water and nutrients.


Assuntos
Irrigação Agrícola , Agricultura/métodos , Fertilizantes , Microbiologia do Solo , Zea mays , Biomassa , Carbono , Esterco , Nitrogênio , Fixação de Nitrogênio , Solo , Água
4.
Zhonghua Nan Ke Xue ; 20(1): 23-9, 2014 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-24527533

RESUMO

OBJECTIVE: To investigate the expressions of Cx26, Cx32 and Cx43 in prostate cancer (PCa) and benign prostatic hyperplasia (BPH) and their roles in the development and progression of PCa in order to provide some novel evidence for the diagnosis and treatment of PCa. METHODS: We determined the expressions of Cx26, Cx32 and Cx43 in the paraffin samples from 31 cases of PCa and 23 cases of BPH by SABC immunohistochemical staining, and analyzed the relationship of their expressions with the clinical and pathological parameters of PCa and BPH using the semiquantitative method. RESULTS: The positive expressions of Cx26 in BPH and PCa were 82.6% and 74.2%, respectively (chi2 = 0.541, P > 0.05), those of Cx32 were 78.3% and 61.3% (chi2 = 1.763, P > 0.05), and those of Cx43 were 87.0% and 38.7% (chi2 = 12.730, P < 0.01). The staining intensities of Cx26 and Cx43 were negatively correlated with the malignant phenotype of PCa (rCx26 = -0.476, P < 0.01; rCx43 = -0.484, P < 0.01), but not the expression of Cx32 (r = -0.242, P > 0.05). The three Cxs exhibited no correlation with the age and serum PSA level of the patients (P > 0.05), nor among their expressions (P > 0.05). CONCLUSION: Cx26, Cx32 and Cx43 are expressed in different degrees in BPH and PCa tissues. Cx43 plays a role in the occurrence and progression of PCa, and may serve as a new marker of PCa besides PSA as well as a new target in the biotherapy of PCa. Cx26 may be partially involved in the progression of PCa, but its mechanisms need to be further studied.


Assuntos
Conexina 43/metabolismo , Conexinas/metabolismo , Próstata/metabolismo , Neoplasias da Próstata/metabolismo , Idoso , Idoso de 80 Anos ou mais , Conexina 26 , Humanos , Masculino
5.
Chin Med J (Engl) ; 126(10): 1890-4, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23673105

RESUMO

BACKGROUND: Chronic kidney disease (CDK) is a worldwide health problem, but there is currently no effective treatment that can completely cure this disease. Recently, studies with mesenchymal stem cells (MSCs) on treating various renal diseases have shown breakthroughs. This study is to observe the homing features of MSCs transplanted via kidney artery and effects on renal fibrosis in a reversible unilateral ureteral obstruction (R-UUO) model. METHODS: Thirty-six Balb/c mice were divided into UUO group, UUO-MSC group, and sham group randomly, with 12 mice in each group. The MSCs had been infected by a lentiviral vector to express stably the luciferase reporter gene and green fluorescence protein genes (Luc-GFP-MSC). Homing of MSCs was tracked using in vivo imaging system (IVIS) 1, 3, 14, and 28 days after transplantation. Imaging results were verified by detecting GFP expression in frozen section under a fluorescence microscope. E-cadherin, α-SMA, TGF-ß1, and TNF-α mRNA expression in all groups at 1 and 4 weeks after transplantation were analyzed by quantitative PCR. RESULTS: Transplanted Luc-GFP-MSCs showed increased Luciferase expression 3 days after transplantation. The expression decreased from 7 days, weakened thereafter and could not be detected 14 days after transplantation. Quantitative PCR results showed that all gene expressions in UUO group and UUO-MSC group at 1 week had no statistical difference, while at 4 weeks, except TGF-ß expression (P > 0.05), the expression of E-cadherin, α-SMA, and TNF-α in the above two groups have statistical difference (P < 0.01). CONCLUSION: IVIS enables fast, noninvasive, and intuitive tracking of MSC homing in vivo. MSCs can be taken home to kidney tissues of the diseased side in R-UUO model, and renal interstitial fibrosis can be improved as well.


Assuntos
Fibrose/patologia , Nefropatias/patologia , Transplante de Células-Tronco Mesenquimais/métodos , Obstrução Ureteral/terapia , Animais , Células Cultivadas , Fibrose/terapia , Nefropatias/terapia , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/fisiologia , Camundongos , Camundongos Endogâmicos BALB C , Reação em Cadeia da Polimerase em Tempo Real
6.
Cell Metab ; 11(5): 402-11, 2010 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-20444420

RESUMO

Mitochondrial fatty acid oxidation provides an important energy source for cellular metabolism, and decreased mitochondrial fatty acid oxidation has been implicated in the pathogenesis of type 2 diabetes. Paradoxically, mice with an inherited deficiency of the mitochondrial fatty acid oxidation enzyme, very long-chain acyl-CoA dehydrogenase (VLCAD), were protected from high-fat diet-induced obesity and liver and muscle insulin resistance. This was associated with reduced intracellular diacylglycerol content and decreased activity of liver protein kinase Cvarepsilon and muscle protein kinase Ctheta. The increased insulin sensitivity in the VLCAD(-/-) mice were protected from diet-induced obesity and insulin resistance due to chronic activation of AMPK and PPARalpha, resulting in increased fatty acid oxidation and decreased intramyocellular and hepatocellular diacylglycerol content.


Assuntos
Acil-CoA Desidrogenase de Cadeia Longa/metabolismo , Resistência à Insulina , Obesidade/etiologia , Acil-CoA Desidrogenase de Cadeia Longa/deficiência , Acil-CoA Desidrogenase de Cadeia Longa/genética , Animais , Gorduras na Dieta/farmacologia , Diglicerídeos/metabolismo , Humanos , Insulina/metabolismo , Isoenzimas/metabolismo , Fígado/enzimologia , Fígado/metabolismo , Masculino , Camundongos , Camundongos Knockout , Mitocôndrias/enzimologia , PPAR alfa/metabolismo , Proteína Quinase C/metabolismo , Proteína Quinase C-épsilon/metabolismo , Proteína Quinase C-theta , Proteínas Quinases/metabolismo
7.
Proc Natl Acad Sci U S A ; 105(50): 19926-31, 2008 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-19066218

RESUMO

Peroxisome proliferator-activated receptor-gamma coactivator (PGC)-1alpha has been shown to play critical roles in regulating mitochondria biogenesis, respiration, and muscle oxidative phenotype. Furthermore, reductions in the expression of PGC-1alpha in muscle have been implicated in the pathogenesis of type 2 diabetes. To determine the effect of increased muscle-specific PGC-1alpha expression on muscle mitochondrial function and glucose and lipid metabolism in vivo, we examined body composition, energy balance, and liver and muscle insulin sensitivity by hyperinsulinemic-euglycemic clamp studies and muscle energetics by using (31)P magnetic resonance spectroscopy in transgenic mice. Increased expression of PGC-1alpha in muscle resulted in a 2.4-fold increase in mitochondrial density, which was associated with an approximately 60% increase in the unidirectional rate of ATP synthesis. Surprisingly, there was no effect of increased muscle PGC-1alpha expression on whole-body energy expenditure, and PGC-1alpha transgenic mice were more prone to fat-induced insulin resistance because of decreased insulin-stimulated muscle glucose uptake. The reduced insulin-stimulated muscle glucose uptake could most likely be attributed to a relative increase in fatty acid delivery/triglyceride reesterfication, as reflected by increased expression of CD36, acyl-CoA:diacylglycerol acyltransferase1, and mitochondrial acyl-CoA:glycerol-sn-3-phosphate acyltransferase, that may have exceeded mitochondrial fatty acid oxidation, resulting in increased intracellular lipid accumulation and an increase in the membrane to cytosol diacylglycerol content. This, in turn, caused activation of PKC, decreased insulin signaling at the level of insulin receptor substrate-1 (IRS-1) tyrosine phosphorylation, and skeletal muscle insulin resistance.


Assuntos
Glucose/metabolismo , Mitocôndrias Musculares/metabolismo , Músculo Esquelético/metabolismo , Transativadores/biossíntese , Animais , Dieta , Metabolismo Energético , Gorduras/administração & dosagem , Gorduras/metabolismo , Ácidos Graxos/metabolismo , Expressão Gênica , Insulina/farmacologia , Resistência à Insulina , Camundongos , Camundongos Transgênicos , Mitocôndrias Musculares/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/ultraestrutura , Oxirredução , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Fatores de Transcrição
8.
Acta Crystallogr Sect E Struct Rep Online ; 65(Pt 1): m48-9, 2008 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-21581519

RESUMO

The hydro-thermal reaction of Ni(2)(OH)(2)CO(3) with 2,2'-bipyridine and 2-indolyl-formic acid in CH(3)OH/H(2)O at 423 K for 7 d produced the novel Ni(II) complex [Ni(C(9)H(6)NO(2))(C(10)H(8)N(2))(2)(H(2)O)](C(9)H(6)NO(2))·2H(2)O. The asymmetric unit of the title compound consists of a monovalent [Ni(L)(bpy)(2)(H(2)O)](+) cation (bpy is 2,2'-bipyridine and L is 1H-indole-2-carboxyl-ate), an L anion and two solvent water mol-ecules. In the [Ni(L)(bpy)(2)(H(2)O)](+) cations, the Ni atom coordinates to four N atoms from the two bpy ligands and two O atoms, one from a L anion and the other from a water mol-ecule to complete an significantly distorted NiN(4)O(2) octa-hedron. The coordinated and solvate water mol-ecules form an extensive series of O-H⋯O hydrogen bonds. N-H⋯O and C-H⋯O hydrogen bonds are also present and the mol-ecules are inter-linked, forming a three-dimensional network.

9.
Proc Natl Acad Sci U S A ; 104(42): 16480-5, 2007 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-17923673

RESUMO

Acetyl-CoA carboxylase 2 (ACC)2 is a key regulator of mitochondrial fat oxidation. To examine the impact of ACC2 deletion on whole-body energy metabolism, we measured changes in substrate oxidation and total energy expenditure in Acc2(-/-) and WT control mice fed either regular or high-fat diets. To determine insulin action in vivo, we also measured whole-body insulin-stimulated liver and muscle glucose metabolism during a hyperinsulinemic-euglycemic clamp in Acc2(-/-) and WT control mice fed a high-fat diet. Contrary to previous studies that have suggested that increased fat oxidation might result in lower glucose oxidation, both fat and carbohydrate oxidation were simultaneously increased in Acc2(-/-) mice. This increase in both fat and carbohydrate oxidation resulted in an increase in total energy expenditure, reductions in fat and lean body mass and prevention from diet-induced obesity. Furthermore, Acc2(-/-) mice were protected from fat-induced peripheral and hepatic insulin resistance. These improvements in insulin-stimulated glucose metabolism were associated with reduced diacylglycerol content in muscle and liver, decreased PKC activity in muscle and PKCepsilon activity in liver, and increased insulin-stimulated Akt2 activity in these tissues. Taken together with previous work demonstrating that Acc2(-/-) mice have a normal lifespan, these data suggest that Acc2 inhibition is a viable therapeutic option for the treatment of obesity and type 2 diabetes.


Assuntos
Acetil-CoA Carboxilase/genética , Tecido Adiposo/enzimologia , Resistência à Insulina/genética , Insulina/farmacologia , Animais , Citocinas/metabolismo , Metabolismo Energético/genética , Glucose/metabolismo , Isoenzimas/metabolismo , Fígado/enzimologia , Camundongos , Camundongos Knockout , Músculo Esquelético/enzimologia , Oxirredução , Proteína Quinase C/metabolismo , Proteína Quinase C-épsilon/metabolismo , Proteína Quinase C-theta
10.
Proc Natl Acad Sci U S A ; 104(43): 17075-80, 2007 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-17940018

RESUMO

Alterations in mitochondrial function have been implicated in the pathogenesis of insulin resistance and type 2 diabetes. However, it is unclear whether the reduced mitochondrial function is a primary or acquired defect in this process. To determine whether primary defects in mitochondrial beta-oxidation can cause insulin resistance, we studied mice with a deficiency of long-chain acyl-CoA dehydrogenase (LCAD), a key enzyme in mitochondrial fatty acid oxidation. Here, we show that LCAD knockout mice develop hepatic steatosis, which is associated with hepatic insulin resistance, as reflected by reduced insulin suppression of hepatic glucose production during a hyperinsulinemic-euglycemic clamp. The defects in insulin action were associated with an approximately 40% reduction in insulin-stimulated insulin receptor substrate-2-associated phosphatidylinositol 3-kinase activity and an approximately 50% decrease in Akt2 activation. These changes were associated with increased PKCepsilon activity and an aberrant 4-fold increase in diacylglycerol content after insulin stimulation. The increase in diacylglycerol concentration was found to be caused by de novo synthesis of diacylglycerol from medium-chain acyl-CoA after insulin stimulation. These data demonstrate that primary defects in mitochondrial fatty acid oxidation capacity can lead to diacylglycerol accumulation, PKCepsilon activation, and hepatic insulin resistance.


Assuntos
Acil-CoA Desidrogenase de Cadeia Longa/deficiência , Fígado Gorduroso/enzimologia , Resistência à Insulina/fisiologia , Fígado/enzimologia , Fígado/patologia , Mitocôndrias/enzimologia , Mitocôndrias/patologia , Acil Coenzima A/metabolismo , Animais , Calorimetria , Isótopos de Carbono , Diglicerídeos/biossíntese , Metabolismo Energético/efeitos dos fármacos , Fígado Gorduroso/patologia , Regulação da Expressão Gênica/efeitos dos fármacos , Glucose/metabolismo , Homeostase/efeitos dos fármacos , Insulina/farmacologia , Fígado/metabolismo , Camundongos , Mitocôndrias/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismo , Oxirredução/efeitos dos fármacos , Proteína Quinase C-épsilon/metabolismo , Transdução de Sinais/efeitos dos fármacos , Triglicerídeos/biossíntese
11.
J Clin Invest ; 117(7): 1995-2003, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17571165

RESUMO

Insulin resistance is a major factor in the pathogenesis of type 2 diabetes and is strongly associated with obesity. Increased concentrations of intracellular fatty acid metabolites have been postulated to interfere with insulin signaling by activation of a serine kinase cascade involving PKCtheta in skeletal muscle. Uncoupling protein 3 (UCP3) has been postulated to dissipate the mitochondrial proton gradient and cause metabolic inefficiency. We therefore hypothesized that overexpression of UCP3 in skeletal muscle might protect against fat-induced insulin resistance in muscle by conversion of intramyocellular fat into thermal energy. Wild-type mice fed a high-fat diet were markedly insulin resistant, a result of defects in insulin-stimulated glucose uptake in skeletal muscle and hepatic insulin resistance. Insulin resistance in these tissues was associated with reduced insulin-stimulated insulin receptor substrate 1- (IRS-1-) and IRS-2-associated PI3K activity in muscle and liver, respectively. In contrast, UCP3-overexpressing mice were completely protected against fat-induced defects in insulin signaling and action in these tissues. Furthermore, these changes were associated with a lower membrane-to-cytosolic ratio of diacylglycerol and reduced PKCtheta activity in whole-body fat-matched UCP3 transgenic mice. These results suggest that increasing mitochondrial uncoupling in skeletal muscle may be an excellent therapeutic target for type 2 diabetes mellitus.


Assuntos
Regulação da Expressão Gênica , Resistência à Insulina , Canais Iônicos/metabolismo , Metabolismo dos Lipídeos , Proteínas Mitocondriais/metabolismo , Músculo Esquelético/metabolismo , Proteínas Quinases Ativadas por AMP , Envelhecimento/fisiologia , Animais , Ativação Enzimática , Hormônios/sangue , Humanos , Insulina/sangue , Canais Iônicos/genética , Isoenzimas/metabolismo , Masculino , Camundongos , Camundongos Transgênicos , Proteínas Mitocondriais/genética , Complexos Multienzimáticos/metabolismo , Proteína Quinase C/metabolismo , Proteína Quinase C-theta , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteína Desacopladora 3 , Ganho de Peso
12.
J Biol Chem ; 282(31): 22678-88, 2007 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-17526931

RESUMO

Nonalcoholic fatty liver disease (NAFLD) is a major contributing factor to hepatic insulin resistance in type 2 diabetes. Diacylglycerol acyltransferase (Dgat), of which there are two isoforms (Dgat1 and Dgat2), catalyzes the final step in triglyceride synthesis. We evaluated the metabolic impact of pharmacological reduction of DGAT1 and -2 expression in liver and fat using antisense oligonucleotides (ASOs) in rats with diet-induced NAFLD. Dgat1 and Dgat2 ASO treatment selectively reduced DGAT1 and DGAT2 mRNA levels in liver and fat, but only Dgat2 ASO treatment significantly reduced hepatic lipids (diacylglycerol and triglyceride but not long chain acyl CoAs) and improved hepatic insulin sensitivity. Because Dgat catalyzes triglyceride synthesis from diacylglycerol, and because we have hypothesized that diacylglycerol accumulation triggers fat-induced hepatic insulin resistance through protein kinase C epsilon activation, we next sought to understand the paradoxical reduction in diacylglycerol in Dgat2 ASO-treated rats. Within 3 days of starting Dgat2 ASO therapy in high fat-fed rats, plasma fatty acids increased, whereas hepatic lysophosphatidic acid and diacylglycerol levels were similar to those of control rats. These changes were associated with reduced expression of lipogenic genes (SREBP1c, ACC1, SCD1, and mtGPAT) and increased expression of oxidative/thermogenic genes (CPT1 and UCP2). Taken together, these data suggest that knocking down Dgat2 protects against fat-induced hepatic insulin resistance by paradoxically lowering hepatic diacylglycerol content and protein kinase C epsilon activation through decreased SREBP1c-mediated lipogenesis and increased hepatic fatty acid oxidation.


Assuntos
Diacilglicerol O-Aciltransferase/fisiologia , Fígado Gorduroso/patologia , Resistência à Insulina , Oligonucleotídeos Antissenso/química , Animais , Diacilglicerol O-Aciltransferase/metabolismo , Dieta , Ácidos Graxos/metabolismo , Fígado Gorduroso/terapia , Hepatócitos/metabolismo , Fígado/metabolismo , Masculino , Oxigênio/metabolismo , Ratos , Ratos Sprague-Dawley , Triglicerídeos/metabolismo
13.
J Biol Chem ; 282(20): 14807-15, 2007 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-17389595

RESUMO

Fatty liver is commonly associated with insulin resistance and type 2 diabetes, but it is unclear whether triacylglycerol accumulation or an excess flux of lipid intermediates in the pathway of triacyglycerol synthesis are sufficient to cause insulin resistance in the absence of genetic or diet-induced obesity. To determine whether increased glycerolipid flux can, by itself, cause hepatic insulin resistance, we used an adenoviral construct to overexpress glycerol-sn-3-phosphate acyltransferase-1 (Ad-GPAT1), the committed step in de novo triacylglycerol synthesis. After 5-7 days, food intake, body weight, and fat pad weight did not differ between Ad-GPAT1 and Ad-enhanced green fluorescent protein control rats, but the chow-fed Ad-GPAT1 rats developed fatty liver, hyperlipidemia, and insulin resistance. Liver was the predominant site of insulin resistance; Ad-GPAT1 rats had 2.5-fold higher hepatic glucose output than controls during a hyperinsulinemic-euglycemic clamp. Hepatic diacylglycerol and lysophosphatidate were elevated in Ad-GPAT1 rats, suggesting a role for these lipid metabolites in the development of hepatic insulin resistance, and hepatic protein kinase Cepsilon was activated, providing a potential mechanism for insulin resistance. Ad-GPAT1-treated rats had 50% lower hepatic NF-kappaB activity and no difference in expression of tumor necrosis factor-alpha and interleukin-beta, consistent with hepatic insulin resistance in the absence of increased hepatic inflammation. Glycogen synthesis and uptake of 2-deoxyglucose were reduced in skeletal muscle, suggesting mild peripheral insulin resistance associated with a higher content of skeletal muscle triacylglycerol. These results indicate that increased flux through the pathway of hepatic de novo triacylglycerol synthesis can cause hepatic and systemic insulin resistance in the absence of obesity or a lipogenic diet.


Assuntos
Glicerol-3-Fosfato O-Aciltransferase/biossíntese , Resistência à Insulina , Metabolismo dos Lipídeos , Fígado/enzimologia , Adenoviridae , Animais , Desoxiglucose/metabolismo , Fígado Gorduroso/enzimologia , Fígado Gorduroso/genética , Fígado Gorduroso/patologia , Expressão Gênica , Glicerol-3-Fosfato O-Aciltransferase/genética , Glicogênio/metabolismo , Hiperlipidemias/enzimologia , Hiperlipidemias/genética , Hiperlipidemias/patologia , Resistência à Insulina/genética , Interleucina-1beta/biossíntese , Metabolismo dos Lipídeos/genética , Fígado/patologia , Masculino , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , NF-kappa B/biossíntese , Proteína Quinase C-épsilon/metabolismo , Ratos , Ratos Wistar , Transdução Genética , Triglicerídeos/biossíntese , Fator de Necrose Tumoral alfa/biossíntese
14.
Cell Metab ; 5(2): 151-6, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17276357

RESUMO

Recent studies have demonstrated a strong relationship between aging-associated reductions in mitochondrial function, dysregulated intracellular lipid metabolism, and insulin resistance. Given the important role of the AMP-activated protein kinase (AMPK) in the regulation of fat oxidation and mitochondrial biogenesis, we examined AMPK activity in young and old rats and found that acute stimulation of AMPK-alpha(2) activity by 5'-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR) and exercise was blunted in skeletal muscle of old rats. Furthermore, mitochondrial biogenesis in response to chronic activation of AMPK with beta-guanidinopropionic acid (beta-GPA) feeding was also diminished in old rats. These results suggest that aging-associated reductions in AMPK activity may be an important contributing factor in the reduced mitochondrial function and dysregulated intracellular lipid metabolism associated with aging.


Assuntos
Envelhecimento , Mitocôndrias/enzimologia , Complexos Multienzimáticos/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Quinases Ativadas por AMP , Aminoimidazol Carboxamida/análogos & derivados , Aminoimidazol Carboxamida/farmacologia , Animais , Guanidinas/administração & dosagem , Guanidinas/farmacologia , Masculino , Mitocôndrias/efeitos dos fármacos , Condicionamento Físico Animal , Propionatos/administração & dosagem , Propionatos/farmacologia , Ratos , Ratos Endogâmicos F344 , Ribonucleotídeos/farmacologia
15.
J Clin Invest ; 117(3): 739-45, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17318260

RESUMO

Nonalcoholic fatty liver disease is strongly associated with hepatic insulin resistance and type 2 diabetes mellitus, but the molecular signals linking hepatic fat accumulation to hepatic insulin resistance are unknown. Three days of high-fat feeding in rats results specifically in hepatic steatosis and hepatic insulin resistance. In this setting, PKCepsilon, but not other isoforms of PKC, is activated. To determine whether PKCepsilon plays a causal role in the pathogenesis of hepatic insulin resistance, we treated rats with an antisense oligonucleotide against PKCepsilon and subjected them to 3 days of high-fat feeding. Knocking down PKCepsilon expression protects rats from fat-induced hepatic insulin resistance and reverses fat-induced defects in hepatic insulin signaling. Furthermore, we show that PKCepsilon associates with the insulin receptor in vivo and impairs insulin receptor kinase activity both in vivo and in vitro. These data support the hypothesis that PKCepsilon plays a critical role in mediating fat-induced hepatic insulin resistance and represents a novel therapeutic target for type 2 diabetes.


Assuntos
Fígado Gorduroso/enzimologia , Resistência à Insulina , Insulina/metabolismo , Proteína Quinase C-épsilon/fisiologia , Animais , Insulina/sangue , Resistência à Insulina/genética , Metabolismo dos Lipídeos , Masculino , Oligonucleotídeos Antissenso/farmacologia , Proteína Quinase C-épsilon/antagonistas & inibidores , Proteína Quinase C-épsilon/genética , Ratos , Ratos Sprague-Dawley , Receptor de Insulina/agonistas , Transdução de Sinais
16.
J Clin Invest ; 116(3): 817-24, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16485039

RESUMO

Hepatic steatosis is a core feature of the metabolic syndrome and type 2 diabetes and leads to hepatic insulin resistance. Malonyl-CoA, generated by acetyl-CoA carboxylases 1 and 2 (Acc1 and Acc2), is a key regulator of both mitochondrial fatty acid oxidation and fat synthesis. We used a diet-induced rat model of nonalcoholic fatty liver disease (NAFLD) and hepatic insulin resistance to explore the impact of suppressing Acc1, Acc2, or both Acc1 and Acc2 on hepatic lipid levels and insulin sensitivity. While suppression of Acc1 or Acc2 expression with antisense oligonucleotides (ASOs) increased fat oxidation in rat hepatocytes, suppression of both enzymes with a single ASO was significantly more effective in promoting fat oxidation. Suppression of Acc1 also inhibited lipogenesis whereas Acc2 reduction had no effect on lipogenesis. In rats with NAFLD, suppression of both enzymes with a single ASO was required to significantly reduce hepatic malonyl-CoA levels in vivo, lower hepatic lipids (long-chain acyl-CoAs, diacylglycerol, and triglycerides), and improve hepatic insulin sensitivity. Plasma ketones were significantly elevated compared with controls in the fed state but not in the fasting state, indicating that lowering Acc1 and -2 expression increases hepatic fat oxidation specifically in the fed state. These studies suggest that pharmacological inhibition of Acc1 and -2 may be a novel approach in the treatment of NAFLD and hepatic insulin resistance.


Assuntos
Acetil-CoA Carboxilase/antagonistas & inibidores , Dieta , Inibidores Enzimáticos/uso terapêutico , Fígado Gorduroso/tratamento farmacológico , Fígado Gorduroso/enzimologia , Resistência à Insulina/fisiologia , Oligonucleotídeos Antissenso/uso terapêutico , Acetil-CoA Carboxilase/genética , Animais , Ácidos Graxos/metabolismo , Hepatócitos/metabolismo , Ratos , Transdução de Sinais/fisiologia , Triglicerídeos/biossíntese
17.
Cell Metab ; 2(1): 55-65, 2005 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16054099

RESUMO

In order to investigate the role of mitochondrial acyl-CoA:glycerol-sn-3-phosphate acyltransferase 1 (mtGPAT1) in the pathogenesis of hepatic steatosis and hepatic insulin resistance, we examined whole-body insulin action in awake mtGPAT1 knockout (mtGPAT1(-/-)) and wild-type (wt) mice after regular control diet or three weeks of high-fat feeding. In contrast to high-fat-fed wt mice, mtGPAT1(-/-) mice displayed markedly lower hepatic triacylglycerol and diacylglycerol concentrations and were protected from hepatic insulin resistance possibly due to a lower diacylglycerol-mediated PKC activation. Hepatic acyl-CoA has previously been implicated in the pathogenesis of insulin resistance. Surprisingly, compared to wt mice, mtGPAT1(-/-) mice exhibited increased hepatic insulin sensitivity despite an almost 2-fold elevation in hepatic acyl-CoA content. These data suggest that mtGPAT1 might serve as a novel target for treatment of hepatic steatosis and hepatic insulin resistance and that long chain acyl-CoA's do not mediate fat-induced hepatic insulin resistance in this model.


Assuntos
Fígado Gorduroso/enzimologia , Fígado Gorduroso/prevenção & controle , Glicerol-3-Fosfato O-Aciltransferase/deficiência , Resistência à Insulina/genética , Fígado/enzimologia , Mitocôndrias/enzimologia , Proteínas Quinases Ativadas por AMP , Acetilcoenzima A/metabolismo , Acetil-CoA Carboxilase/metabolismo , Animais , Gorduras na Dieta/administração & dosagem , Gorduras na Dieta/farmacologia , Diglicerídeos/metabolismo , Jejum , Fígado Gorduroso/genética , Teste de Tolerância a Glucose , Glicerol-3-Fosfato O-Aciltransferase/genética , Glicerol-3-Fosfato O-Aciltransferase/metabolismo , Fígado/citologia , Fígado/metabolismo , Fígado/patologia , Lisofosfolipídeos/metabolismo , Masculino , Malonil Coenzima A/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mitocôndrias/genética , Complexos Multienzimáticos/metabolismo , Fenótipo , Proteínas Serina-Treonina Quinases/metabolismo , Triglicerídeos/metabolismo
18.
Diabetes ; 54(6): 1657-63, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15919786

RESUMO

Insulin resistance plays a major role in the development of type 2 diabetes and may be causally associated with increased intracellular fat content. Transgenic mice with adipocyte-specific overexpression of FOXC2 (forkhead transcription factor) have been generated and shown to be protected against diet-induced obesity and glucose intolerance. To understand the underlying mechanism, we examined the effects of chronic high-fat feeding on tissue-specific insulin action and glucose metabolism in the FOXC2 transgenic (Tg) mice. Whole-body fat mass were significantly reduced in the FOXC2 Tg mice fed normal diet or high-fat diet compared with the wild-type mice. Diet-induced insulin resistance in skeletal muscle of the wild-type mice was associated with defects in insulin signaling and significant increases in intramuscular fatty acyl CoA levels. In contrast, FOXC2 Tg mice were completely protected from diet-induced insulin resistance and intramuscular accumulation of fatty acyl CoA. High-fat feeding also blunted insulin-mediated suppression of hepatic glucose production in the wild-type mice, whereas FOXC2 Tg mice were protected from diet-induced hepatic insulin resistance. These findings demonstrate an important role of adipocyte-expressed FOXC2 on whole-body glucose metabolism and further suggest FOXC2 as a novel therapeutic target for the treatment of insulin resistance and type 2 diabetes.


Assuntos
Acil Coenzima A/metabolismo , Adipócitos/metabolismo , Proteínas de Ligação a DNA/fisiologia , Gorduras na Dieta/metabolismo , Resistência à Insulina , Músculo Esquelético/metabolismo , Fatores de Transcrição/fisiologia , Animais , Proteínas de Ligação a DNA/biossíntese , Proteínas de Ligação a DNA/genética , Fatores de Transcrição Forkhead , Expressão Gênica , Insulina/metabolismo , Masculino , Camundongos , Camundongos Transgênicos , Transdução de Sinais , Fatores de Transcrição/biossíntese , Fatores de Transcrição/genética
19.
Mol Cell ; 16(2): 257-67, 2004 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-15494312

RESUMO

Activation of the hepatocyte growth factor (HGF) receptor in epithelial cells results in lamellipodia protrusion, spreading, migration, and tubule formation. We have previously reported that these morphogenic effects are dependent on MAPK activation at focal adhesions. In the present study we demonstrate that activated ERK phosphorylates paxillin on serine 83 and that mutation of this site eliminates HGF-stimulated increased association of paxillin and FAK in subconfluent cells. Failure to activate FAK at focal adhesions results in a loss of FAK-PI 3-kinase association and the marked reduction of Rac activation after HGF stimulation. Expression of paxillin mutants that disrupt ERK association or phosphorylation inhibits HGF-induced cell spreading, migration, and tubulogenesis. These data demonstrate that the paxillin-MAPK complex serves as a central regulator of HGF-stimulated FAK and Rac activation in the vicinity of focal adhesions, thus promoting the rapid focal adhesion turnover and lamellipodia extension that are required for migratory and tubulogenic responses.


Assuntos
Proteínas do Citoesqueleto/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Fosfoproteínas/metabolismo , Proteínas Tirosina Quinases/metabolismo , Proteínas rac de Ligação ao GTP/metabolismo , Animais , Epitélio/metabolismo , Quinase 1 de Adesão Focal , Proteína-Tirosina Quinases de Adesão Focal , Fator de Crescimento de Hepatócito/metabolismo , Túbulos Renais Coletores/metabolismo , Camundongos , Paxilina , Fosforilação , Serina/metabolismo , Transdução de Sinais
20.
J Clin Invest ; 114(6): 823-7, 2004 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-15372106

RESUMO

Insulin resistance plays a primary role in the development of type 2 diabetes and may be related to alterations in fat metabolism. Recent studies have suggested that local accumulation of fat metabolites inside skeletal muscle may activate a serine kinase cascade involving protein kinase C-theta (PKC-theta), leading to defects in insulin signaling and glucose transport in skeletal muscle. To test this hypothesis, we examined whether mice with inactivation of PKC-theta are protected from fat-induced insulin resistance in skeletal muscle. Skeletal muscle and hepatic insulin action as assessed during hyperinsulinemic-euglycemic clamps did not differ between WT and PKC-theta KO mice following saline infusion. A 5-hour lipid infusion decreased insulin-stimulated skeletal muscle glucose uptake in the WT mice that was associated with 40-50% decreases in insulin-stimulated tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1) and IRS-1-associated PI3K activity. In contrast, PKC-theta inactivation prevented fat-induced defects in insulin signaling and glucose transport in skeletal muscle. In conclusion, our findings demonstrate that PKC-theta is a crucial component mediating fat-induced insulin resistance in skeletal muscle and suggest that PKC-theta is a potential therapeutic target for the treatment of type 2 diabetes.


Assuntos
Tecido Adiposo/fisiologia , Resistência à Insulina/genética , Isoenzimas/deficiência , Isoenzimas/genética , Proteína Quinase C/deficiência , Proteína Quinase C/genética , Animais , Glicemia/metabolismo , Diabetes Mellitus Tipo 2/terapia , Ácidos Graxos não Esterificados/sangue , Infusões Intravenosas , Insulina/sangue , Insulina/fisiologia , Proteínas Substratos do Receptor de Insulina , Isoenzimas/uso terapêutico , Lipídeos/administração & dosagem , Lipídeos/farmacologia , Camundongos , Camundongos Knockout , Músculo Esquelético/fisiologia , Fosfoproteínas/metabolismo , Fosforilação , Proteína Quinase C/uso terapêutico , Proteína Quinase C-theta , Transdução de Sinais/genética , Transdução de Sinais/fisiologia
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