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2.
Mol Cell Proteomics ; 21(3): 100207, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35093608

RESUMO

Obesity leads to the development of nonalcoholic fatty liver disease (NAFLD) and associated alterations to the plasma proteome. To elucidate the underlying changes associated with obesity, we performed liquid chromatography-tandem mass spectrometry in the liver and plasma of obese leptin-deficient ob/ob mice and integrated these data with publicly available transcriptomic and proteomic datasets of obesity and metabolic diseases in preclinical and clinical cohorts. We quantified 7173 and 555 proteins in the liver and plasma proteomes, respectively. The abundance of proteins related to fatty acid metabolism were increased, alongside peroxisomal proliferation in ob/ob liver. Putatively secreted proteins and the secretory machinery were also dysregulated in the liver, which was mirrored by a substantial alteration of the plasma proteome. Greater than 50% of the plasma proteins were differentially regulated, including NAFLD biomarkers, lipoproteins, the 20S proteasome, and the complement and coagulation cascades of the immune system. Integration of the liver and plasma proteomes identified proteins that were concomitantly regulated in the liver and plasma in obesity, suggesting that the systemic abundance of these plasma proteins is regulated by secretion from the liver. Many of these proteins are systemically regulated during type 2 diabetes and/or NAFLD in humans, indicating the clinical importance of liver-plasma cross talk and the relevance of our investigations in ob/ob mice. Together, these analyses yield a comprehensive insight into obesity and provide an extensive resource for obesity research in a prevailing model organism.


Assuntos
Diabetes Mellitus Tipo 2 , Hepatopatia Gordurosa não Alcoólica , Animais , Diabetes Mellitus Tipo 2/metabolismo , Fígado/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Obesos , Hepatopatia Gordurosa não Alcoólica/metabolismo , Proteômica
3.
Cell ; 132(3): 375-86, 2008 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-18267070

RESUMO

Type 2 (non-insulin-dependent) diabetes mellitus is a progressive metabolic disorder arising from genetic and environmental factors that impair beta cell function and insulin action in peripheral tissues. We identified reduced diacylglycerol kinase delta (DGKdelta) expression and DGK activity in skeletal muscle from type 2 diabetic patients. In diabetic animals, reduced DGKdelta protein and DGK kinase activity were restored upon correction of glycemia. DGKdelta haploinsufficiency increased diacylglycerol content, reduced peripheral insulin sensitivity, insulin signaling, and glucose transport, and led to age-dependent obesity. Metabolic flexibility, evident by the transition between lipid and carbohydrate utilization during fasted and fed conditions, was impaired in DGKdelta haploinsufficient mice. We reveal a previously unrecognized role for DGKdelta in contributing to hyperglycemia-induced peripheral insulin resistance and thereby exacerbating the severity of type 2 diabetes. DGKdelta deficiency causes peripheral insulin resistance and metabolic inflexibility. These defects in glucose and energy homeostasis contribute to mild obesity later in life.


Assuntos
Diabetes Mellitus Tipo 2/genética , Diacilglicerol Quinase/metabolismo , Regulação para Baixo , Resistência à Insulina , Adulto , Envelhecimento , Animais , Diacilglicerol Quinase/genética , Diglicerídeos/metabolismo , Metabolismo Energético , Perfilação da Expressão Gênica , Glucose/metabolismo , Humanos , Hiperglicemia/metabolismo , Metabolismo dos Lipídeos , Masculino , Camundongos , Músculo Esquelético/metabolismo , Obesidade , Proteína Quinase C/metabolismo , Ratos , Ratos Wistar , Transdução de Sinais
4.
Am J Physiol Cell Physiol ; 321(5): C770-C778, 2021 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-34495765

RESUMO

Skeletal muscle is an endocrine organ secreting exercise-induced factors (exerkines), which play a pivotal role in interorgan cross talk. Using mass spectrometry (MS)-based proteomics, we characterized the secretome and identified thymosin ß4 (TMSB4X) as the most upregulated secreted protein in the media of contracting C2C12 myotubes. TMSB4X was also acutely increased in the plasma of exercising humans irrespective of the insulin resistance condition or exercise mode. Treatment of mice with TMSB4X did not ameliorate the metabolic disruptions associated with diet induced-obesity, nor did it enhance muscle regeneration in vivo. However, TMSB4X increased osteoblast proliferation and neurite outgrowth, consistent with its WADA classification as a prohibited growth factor. Therefore, we report TMSB4X as a human exerkine with a potential role in cellular cross talk.


Assuntos
Proliferação de Células/efeitos dos fármacos , Contração Muscular , Fibras Musculares Esqueléticas/metabolismo , Músculo Esquelético/metabolismo , Crescimento Neuronal/efeitos dos fármacos , Osteoblastos/efeitos dos fármacos , Timosina/metabolismo , Timosina/farmacologia , Animais , Estudos de Casos e Controles , Linhagem Celular Tumoral , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/fisiopatologia , Modelos Animais de Doenças , Humanos , Resistência à Insulina , Masculino , Camundongos Endogâmicos C57BL , Músculo Esquelético/patologia , Músculo Esquelético/fisiopatologia , Doenças Musculares/metabolismo , Doenças Musculares/patologia , Doenças Musculares/fisiopatologia , Osteoblastos/patologia , Resistência Física , Proteômica , Transdução de Sinais , Espectrometria de Massas em Tandem
5.
Proc Natl Acad Sci U S A ; 115(9): E2048-E2057, 2018 02 27.
Artigo em Inglês | MEDLINE | ID: mdl-29440408

RESUMO

A single nucleotide substitution in the third intron of insulin-like growth factor 2 (IGF2) is associated with increased muscle mass and reduced subcutaneous fat in domestic pigs. This mutation disrupts the binding of the ZBED6 transcription factor and leads to a threefold up-regulation of IGF2 expression in pig skeletal muscle. Here, we investigated the biological significance of ZBED6-IGF2 interaction in the growth of placental mammals using two mouse models, ZBED6 knock-out (Zbed6-/-) and Igf2 knock-in mice that carry the pig IGF2 mutation. These transgenic mice exhibit markedly higher serum IGF2 concentrations, higher growth rate, increased lean mass, and larger heart, kidney, and liver; no significant changes were observed for white adipose tissues. The changes in body and lean mass were most pronounced in female mice. The phenotypic changes were concomitant with a remarkable up-regulation of Igf2 expression in adult tissues. Transcriptome analysis of skeletal muscle identified differential expression of genes belonging to the extracellular region category. Expression analysis using fetal muscles indicated a minor role of ZBED6 in regulating Igf2 expression prenatally. Furthermore, transcriptome analysis of the adult skeletal muscle revealed that this elevated expression of Igf2 was derived from the P1 and P2 promoters. The results revealed very similar phenotypic effects in the Zbed6 knock-out mouse and in the Igf2 knock-in mouse, showing that the effect of ZBED6 on growth of muscle and internal organs is mediated through the binding site in the Igf2 gene. The results explain why this ZBED6 binding site is extremely well conserved among placental mammals.


Assuntos
Fator de Crescimento Insulin-Like II/fisiologia , Músculo Esquelético/crescimento & desenvolvimento , Proteínas Repressoras/genética , Proteínas Repressoras/fisiologia , Alelos , Animais , Sítios de Ligação , Sequência Conservada , Ilhas de CpG , Elementos de DNA Transponíveis , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Fenótipo , Regiões Promotoras Genéticas , Análise de Sequência de RNA , Transcriptoma , Regulação para Cima
6.
FASEB J ; 33(9): 10551-10562, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31225998

RESUMO

During exercise, skeletal muscles release cytokines, peptides, and metabolites that exert autocrine, paracrine, or endocrine effects on glucose homeostasis. In this study, we investigated the effects of secreted protein acidic and rich in cysteine (SPARC), an exercise-responsive myokine, on glucose metabolism in human and mouse skeletal muscle. SPARC-knockout mice showed impaired systemic metabolism and reduced phosphorylation of AMPK and protein kinase B in skeletal muscle. Treatment of SPARC-knockout mice with recombinant SPARC improved glucose tolerance and concomitantly activated AMPK in skeletal muscle. These effects were dependent on AMPK-γ3 because SPARC treatment enhanced skeletal muscle glucose uptake in wild-type mice but not in AMPK-γ3-knockout mice. SPARC strongly interacted with the voltage-dependent calcium channel, and inhibition of calcium-dependent signaling prevented SPARC-induced AMPK phosphorylation in human and mouse myotubes. Finally, chronic SPARC treatment improved systemic glucose tolerance and AMPK signaling in skeletal muscle of high-fat diet-induced obese mice, highlighting the efficacy of SPARC treatment in the management of metabolic diseases. Thus, our findings suggest that SPARC treatment mimics the effects of exercise on glucose tolerance by enhancing AMPK-dependent glucose uptake in skeletal muscle.-Aoi, W., Hirano, N., Lassiter, D. G., Björnholm, M., Chibalin, A. V., Sakuma, K., Tanimura, Y., Mizushima, K., Takagi, T., Naito, Y., Zierath, J. R., Krook, A. Secreted protein acidic and rich in cysteine (SPARC) improves glucose tolerance via AMP-activated protein kinase activation.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Intolerância à Glucose/prevenção & controle , Glucose/metabolismo , Músculo Esquelético/patologia , Obesidade/prevenção & controle , Osteonectina/fisiologia , Proteínas Quinases Ativadas por AMP/genética , Animais , Dieta Hiperlipídica/efeitos adversos , Feminino , Intolerância à Glucose/metabolismo , Intolerância à Glucose/patologia , Homeostase , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Músculo Esquelético/metabolismo , Obesidade/etiologia , Obesidade/metabolismo , Fosforilação , Transdução de Sinais
7.
Diabetologia ; 62(2): 233-237, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30426166

RESUMO

AIMS/HYPOTHESIS: Exercise is recommended for the treatment and prevention of type 2 diabetes. However, the most effective time of day to achieve beneficial effects on health remains unknown. We aimed to determine whether exercise training at two distinct times of day would have differing effects on 24 h blood glucose levels in men with type 2 diabetes. METHODS: Eleven men with type 2 diabetes underwent a randomised crossover trial. Inclusion criteria were 45-68 years of age and BMI between 23 and 33 kg/m2. Exclusion criteria were insulin treatment and presence of another systemic illness. Researchers were not blinded to the group assignment. The trial involved 2 weeks of either morning or afternoon high-intensity interval training (HIIT) (three sessions/week), followed by a 2 week wash-out period and a subsequent period of the opposite training regimen. Continuous glucose monitor (CGM)-based data were obtained. RESULTS: Morning HIIT increased CGM-based glucose concentration (6.9 ± 0.4 mmol/l; mean ± SEM for the exercise days during week 1) compared with either the pre-training period (6.4 ± 0.3 mmol/l) or afternoon HIIT (6.2 ± 0.3 mmol/l for the exercise days during week 1). Conversely, afternoon HIIT reduced the CGM-based glucose concentration compared with either the pre-training period or morning HIIT. Afternoon HIIT was associated with elevated thyroid-stimulating hormone (TSH; 1.9 ± 0.2 mU/l) and reduced T4 (15.8 ± 0.7 pmol/l) concentrations compared with pre-training (1.4 ± 0.2 mU/l for TSH; 16.8 ± 0.6 pmol/l for T4). TSH was also elevated after morning HIIT (1.7 ± 0.2 mU/l), whereas T4 concentrations were unaltered. CONCLUSIONS/INTERPRETATION: Afternoon HIIT was more efficacious than morning HIIT at improving blood glucose in men with type 2 diabetes. Strikingly, morning HIIT had an acute, deleterious effect, increasing blood glucose. However, studies of longer training regimens are warranted to establish the persistence of this adverse effect. Our data highlight the importance of optimising the timing of exercise when prescribing it as treatment for type 2 diabetes.


Assuntos
Glicemia , Diabetes Mellitus Tipo 2/sangue , Exercício Físico/fisiologia , Estudos Cross-Over , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Tempo , Resultado do Tratamento
8.
Proteomics ; 18(5-6): e1700375, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29350465

RESUMO

Skeletal muscle insulin resistance, an early metabolic defect in the pathogenesis of type 2 diabetes (T2D), may be a cause or consequence of altered protein expression profiles. Proteomics technology offers enormous promise to investigate molecular mechanisms underlying pathologies, however, the analysis of skeletal muscle is challenging. Using state-of-the-art multienzyme digestion and filter-aided sample preparation (MED-FASP) and a mass spectrometry (MS)-based workflow, we performed a global proteomics analysis of skeletal muscle from leptin-deficient, obese, insulin resistant (ob/ob) and lean mice in mere two fractions in a short time (8 h per sample). We identified more than 6000 proteins with 118 proteins differentially regulated in obesity. This included protein kinases, phosphatases, and secreted and fiber type associated proteins. Enzymes involved in lipid metabolism in skeletal muscle from ob/ob mice were increased, providing evidence against reduced fatty acid oxidation in lipid-induced insulin resistance. Mitochondrial and peroxisomal proteins, as well as components of pyruvate and lactate metabolism, were increased. Finally, the skeletal muscle proteome from ob/ob mice displayed a shift toward the "slow fiber type." This detailed characterization of an obese rodent model of T2D demonstrates an efficient workflow for skeletal muscle proteomics, which may easily be adapted to other complex tissues.


Assuntos
Resistência à Insulina , Leptina/fisiologia , Fibras Musculares Esqueléticas/química , Músculo Esquelético/metabolismo , Proteoma/análise , Magreza , Animais , Masculino , Camundongos , Camundongos Obesos , Fibras Musculares Esqueléticas/metabolismo
9.
J Lipid Res ; 59(2): 273-282, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29233919

RESUMO

Conversion of diacylglycerol to phosphatidic acid is mediated by diacylglycerol kinases (DGKs), with DGKα specifically linked to adaptive immune responses. We determined the role of DGKα in obesity and inflammatory responses to a high-fat diet (HFD). DGKα KO and WT littermates were either a) chow-fed, b) HFD-fed for 12 weeks (Long-Term HFD), or c) HFD-fed for 3 days (Acute HFD). Body weight/composition, oxygen consumption, food intake, and glucose tolerance was unaltered between chow-fed DGKα KO and WT mice. Insulin concentration during the intraperitoneal glucose tolerance (IPGT) test was elevated in chow-fed DGKα KO mice, suggesting mild insulin resistance. Insulin concentration during the IPGT test was reduced in Long-Term HFD-fed DGKα KO mice, suggesting a mild enhancement in insulin sensitivity. Acute HFD increased hormone sensitive lipase protein abundance and altered expression of interleukin 1ß mRNA, an inflammatory marker in perigonadal adipose tissue of DGKα KO mice. In conclusion, DGKα ablation is associated with mild alterations in insulin sensitivity. However, DGKα is dispensable for whole body insulin-mediated glucose uptake, hepatic glucose production, and energy homeostasis. Our results suggest DGKα aids in modulating the early immune response of adipose tissue following an acute exposure to HFD, possibly through modulation of acute T-cell action.


Assuntos
Tecido Adiposo/metabolismo , Diacilglicerol Quinase/deficiência , Dieta Hiperlipídica/efeitos adversos , Inflamação/metabolismo , Animais , Biomarcadores/metabolismo , Diacilglicerol Quinase/metabolismo , Modelos Animais de Doenças , Feminino , Glucose/metabolismo , Homeostase , Camundongos , Camundongos Knockout
10.
J Lipid Res ; 58(5): 907-915, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28246337

RESUMO

Diacylglycerol kinases (DGKs) catalyze the phosphorylation and conversion of diacylglycerol (DAG) into phosphatidic acid. DGK isozymes have unique primary structures, expression patterns, subcellular localizations, regulatory mechanisms, and DAG preferences. DGKε has a hydrophobic segment that promotes its attachment to membranes and shows substrate specificity for DAG with an arachidonoyl acyl chain in the sn-2 position of the substrate. We determined the role of DGKε in the regulation of energy and glucose homeostasis in relation to diet-induced insulin resistance and obesity using DGKε-KO and wild-type mice. Lipidomic analysis revealed elevated unsaturated and saturated DAG species in skeletal muscle of DGKε KO mice, which was paradoxically associated with increased glucose tolerance. Although skeletal muscle insulin sensitivity was unaltered, whole-body respiratory exchange ratio was reduced, and abundance of mitochondrial markers was increased, indicating a greater reliance on fat oxidation and intracellular lipid metabolism in DGKε KO mice. Thus, the increased intracellular lipids in skeletal muscle from DGKε KO mice may undergo rapid turnover because of increased mitochondrial function and lipid oxidation, rather than storage, which in turn may preserve insulin sensitivity. In conclusion, DGKε plays a role in glucose and energy homeostasis by modulating lipid metabolism in skeletal muscle.


Assuntos
Diacilglicerol Quinase/deficiência , Glucose/metabolismo , Metabolismo dos Lipídeos , Animais , Composição Corporal , Diacilglicerol Quinase/genética , Metabolismo Energético , Técnicas de Inativação de Genes , Teste de Tolerância a Glucose , Homeostase , Fígado/metabolismo , Masculino , Camundongos , Camundongos Obesos , Mitocôndrias/enzimologia , Mitocôndrias/metabolismo , Músculo Esquelético/citologia , Músculo Esquelético/metabolismo , Oxirredução
11.
J Lipid Res ; 58(12): 2324-2333, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-29066466

RESUMO

Diacylglycerol kinases (DGKs) regulate the balance between diacylglycerol (DAG) and phosphatidic acid. DGKζ is highly abundant in skeletal muscle and induces fiber hypertrophy. We hypothesized that DGKζ influences functional and metabolic adaptations in skeletal muscle and whole-body fuel utilization. DAG content was increased in skeletal muscle and adipose tissue, but unaltered in liver of DGKζ KO mice. Linear growth, body weight, fat mass, and lean mass were reduced in DGKζ KO versus wild-type mice. Conversely, male DGKζ KO and wild-type mice displayed a similar robust increase in plantaris weight after functional overload, suggesting that DGKζ is dispensable for muscle hypertrophy. Although glucose tolerance was similar, insulin levels were reduced in high-fat diet (HFD)-fed DGKζ KO versus wild-type mice. Submaximal insulin-stimulated glucose transport and p-Akt Ser473 were increased, suggesting enhanced skeletal muscle insulin sensitivity. Energy homeostasis was altered in DGKζ KO mice, as evidenced by an elevated respiratory exchange ratio, independent of altered physical activity or food intake. In conclusion, DGKζ deficiency increases tissue DAG content and leads to modest growth retardation, reduced adiposity, and protection against insulin resistance. DGKζ plays a role in the control of growth and metabolic processes, further highlighting specialized functions of DGK isoforms in type 2 diabetes pathophysiology.


Assuntos
Diacilglicerol Quinase/genética , Metabolismo Energético/genética , Glucose/metabolismo , Resistência à Insulina/genética , Insulina/metabolismo , Animais , Transporte Biológico , Diacilglicerol Quinase/deficiência , Dieta Hiperlipídica , Diglicerídeos/metabolismo , Expressão Gênica , Homeostase/genética , Fígado/metabolismo , Masculino , Camundongos , Camundongos Knockout , Músculo Esquelético , Obesidade/etiologia , Obesidade/genética , Obesidade/metabolismo , Obesidade/patologia
12.
Am J Physiol Endocrinol Metab ; 310(6): E461-72, 2016 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-26758685

RESUMO

Mechanisms regulating skeletal muscle growth involve a balance between the activity of serine/threonine protein kinases, including the mammalian target of rapamycin (mTOR) and 5'-AMP-activated protein kinase (AMPK). The contribution of different AMPK subunits to the regulation of cell growth size remains inadequately characterized. Using AMPKγ3 mutant-overexpressing transgenic Tg-Prkag3(225Q) and AMPKγ3-knockout (Prkag3(-/-)) mice, we investigated the requirement for the AMPKγ3 isoform in functional overload-induced muscle hypertrophy. Although the genetic disruption of the γ3 isoform did not impair muscle growth, control sham-operated AMPKγ3-transgenic mice displayed heavier plantaris muscles in response to overload hypertrophy and underwent smaller mass gain and lower Igf1 expression compared with wild-type littermates. The mTOR signaling pathway was upregulated with functional overload but unchanged between genetically modified animals and wild-type littermates. Differences in AMPK-related signaling pathways between transgenic, knockout, and wild-type mice did not impact muscle hypertrophy. Glycogen content was increased following overload in wild-type mice. In conclusion, our functional, transcriptional, and signaling data provide evidence against the involvement of the AMPKγ3 isoform in the regulation of skeletal muscle hypertrophy. Thus, the AMPKγ3 isoform is dispensable for functional overload-induced muscle growth. Mechanical loading can override signaling pathways that act as negative effectors of mTOR signaling and consequently promote skeletal muscle hypertrophy.


Assuntos
Proteínas Quinases Ativadas por AMP/genética , Fator de Crescimento Insulin-Like I/metabolismo , Músculo Esquelético/crescimento & desenvolvimento , Serina-Treonina Quinases TOR/metabolismo , Animais , Hipertrofia/genética , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Músculo Esquelético/metabolismo , Tamanho do Órgão , Transdução de Sinais
13.
Am J Physiol Endocrinol Metab ; 309(7): E679-90, 2015 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-26306597

RESUMO

AMP-activated protein kinase (AMPK) is a major sensor of energy homeostasis and stimulates ATP-generating processes such as lipid oxidation and glycolysis in peripheral tissues. The heterotrimeric enzyme consists of a catalytic α-subunit, a ß-subunit that is important for enzyme activity, and a noncatalytic γ-subunit that binds AMP and activates the AMPK complex. We generated a skeletal muscle Cre-inducible transgenic mouse model expressing a mutant γ1-subunit (AMPKγ1(H151R)), resulting in chronic AMPK activation. The expression of the predominant AMPKγ3 isoform in skeletal muscle was reduced in extensor digitorum longus (EDL) muscle (81-83%) of AMPKγ1(H151R) transgenic mice, whereas the abundance and phosphorylation of the AMPK target acetyl-CoA carboxylase was increased in tibialis anterior muscle. Glycogen content was increased 10-fold in gastrocnemius muscle. Whole body carbohydrate oxidation was increased by 11%, and whereas glucose tolerance was unaffected, insulin sensitivity was increased in AMPKγ1(H151R) transgenic mice. Furthermore, perigonadal white adipose tissue mass and serum leptin were reduced in female AMPKγ1(H151R) transgenic mice by 38 and 51% respectively. Conversely, in male AMPKγ1(H151R) transgenic mice, food intake was increased (14%), but body weight and body composition were unaltered, presumably because of increased energy expenditure. In conclusion, transgenic activation of skeletal muscle AMPKγ1 in this model plays an important sex-specific role in skeletal muscle metabolism and whole body energy homeostasis.


Assuntos
Proteínas Quinases Ativadas por AMP/genética , Metabolismo Energético/genética , Resistência à Insulina/genética , Músculo Esquelético/enzimologia , Proteínas Quinases Ativadas por AMP/metabolismo , Substituição de Aminoácidos , Animais , Arginina/genética , Feminino , Histidina/genética , Homeostase/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Mutação de Sentido Incorreto , Transfecção , Regulação para Cima/genética
14.
Metabolism ; 158: 155939, 2024 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-38843995

RESUMO

BACKGROUND AND AIM: Diacylglycerol kinase (DGK) isoforms catalyze an enzymatic reaction that removes diacylglycerol (DAG) and thereby terminates protein kinase C signaling by converting DAG to phosphatidic acid. DGKδ (type II isozyme) downregulation causes insulin resistance, metabolic inflexibility, and obesity. Here we determined whether DGKδ overexpression prevents these metabolic impairments. METHODS: We generated a transgenic mouse model overexpressing human DGKδ2 under the myosin light chain promoter (DGKδ TG). We performed deep metabolic phenotyping of DGKδ TG mice and wild-type littermates fed chow or high-fat diet (HFD). Mice were also provided free access to running wheels to examine the effects of DGKδ overexpression on exercise-induced metabolic outcomes. RESULTS: DGKδ TG mice were leaner than wild-type littermates, with improved glucose tolerance and increased skeletal muscle glycogen content. DGKδ TG mice were protected against HFD-induced glucose intolerance and obesity. DGKδ TG mice had reduced epididymal fat and enhanced lipolysis. Strikingly, DGKδ overexpression recapitulated the beneficial effects of exercise on metabolic outcomes. DGKδ overexpression and exercise had a synergistic effect on body weight reduction. Microarray analysis of skeletal muscle revealed common gene ontology signatures of exercise and DGKδ overexpression that were related to lipid storage, extracellular matrix, and glycerophospholipids biosynthesis pathways. CONCLUSION: Overexpression of DGKδ induces adaptive changes in both skeletal muscle and adipose tissue, resulting in protection against HFD-induced obesity. DGKδ overexpression recapitulates exercise-induced adaptations on energy homeostasis and skeletal muscle gene expression profiles.

15.
J Biol Chem ; 287(28): 23451-63, 2012 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-22610379

RESUMO

Contraction stimulates Na(+),K(+)-ATPase and AMP-activated protein kinase (AMPK) activity in skeletal muscle. Whether AMPK activation affects Na(+),K(+)-ATPase activity in skeletal muscle remains to be determined. Short term stimulation of rat L6 myotubes with the AMPK activator 5-aminoimidazole-4-carboxamide-1-ß-d-ribofuranoside (AICAR), activates AMPK and promotes translocation of the Na(+),K(+)-ATPase α(1)-subunit to the plasma membrane and increases Na(+),K(+)-ATPase activity as assessed by ouabain-sensitive (86)Rb(+) uptake. Cyanide-induced artificial anoxia, as well as a direct AMPK activator (A-769662) also increase AMPK phosphorylation and Na(+),K(+)-ATPase activity. Thus, different stimuli that target AMPK concomitantly increase Na(+),K(+)-ATPase activity. The effect of AICAR on Na(+),K(+)-ATPase in L6 myotubes was attenuated by Compound C, an AMPK inhibitor, as well as siRNA-mediated AMPK silencing. The effects of AICAR on Na(+),K(+)-ATPase were completely abolished in cultured primary mouse muscle cells lacking AMPK α-subunits. AMPK stimulation leads to Na(+),K(+)-ATPase α(1)-subunit dephosphorylation at Ser(18), which may prevent endocytosis of the sodium pump. AICAR stimulation leads to methylation and dephosphorylation of the catalytic subunit of the protein phosphatase (PP) 2A in L6 myotubes. Moreover, AICAR-triggered dephosphorylation of the Na(+),K(+)-ATPase was prevented in L6 myotubes deficient in PP2A-specific protein phosphatase methylesterase-1 (PME-1), indicating a role for the PP2A·PME-1 complex in AMPK-mediated regulation of Na(+),K(+)-ATPase. Thus contrary to the common paradigm, we report AMPK-dependent activation of an energy-consuming ion pumping process. This activation may be a potential mechanism by which exercise and metabolic stress activate the sodium pump in skeletal muscle.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Fibras Musculares Esqueléticas/enzimologia , Músculo Esquelético/enzimologia , ATPase Trocadora de Sódio-Potássio/metabolismo , Proteínas Quinases Ativadas por AMP/genética , Aminoimidazol Carboxamida/análogos & derivados , Aminoimidazol Carboxamida/farmacologia , Animais , Compostos de Bifenilo , Western Blotting , Hidrolases de Éster Carboxílico/metabolismo , Hipóxia Celular , Células Cultivadas , Ativação Enzimática/efeitos dos fármacos , Metilação/efeitos dos fármacos , Camundongos , Camundongos Knockout , Fibras Musculares Esqueléticas/citologia , Músculo Esquelético/citologia , Fosforilação/efeitos dos fármacos , Proteína Quinase C/metabolismo , Subunidades Proteicas/genética , Subunidades Proteicas/metabolismo , Pironas/farmacologia , Interferência de RNA , Ratos , Ribonucleotídeos/farmacologia , Tiofenos/farmacologia
16.
iScience ; 26(3): 106251, 2023 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-36915683

RESUMO

Habitual exercise alters the intestinal microbiota composition, which may mediate its systemic benefits. We examined whether transplanting fecal microbiota from trained mice improved skeletal muscle metabolism in high-fat diet (HFD)-fed mice. Fecal samples from sedentary and exercise-trained mice were gavage-fed to germ-free mice. After receiving fecal samples from trained donor mice for 1 week, recipient mice had elevated levels of AMP-activated protein kinase (AMPK) and insulin growth factor-1 in skeletal muscle. In plasma, bile acid (BA) deconjugation was found to be promoted in recipients transplanted with feces from trained donor mice; free-form BAs also induced more AMPK signaling and glucose uptake than tauro-conjugated BAs. The transplantation of exercise-acclimated fecal microbiota improved glucose tolerance after 8 weeks of HFD administration. Intestinal microbiota may mediate exercise-induced metabolic improvements in mice by modifying circulating BAs. Our findings provide insights into the prevention and treatment of metabolic diseases.

17.
Am J Physiol Endocrinol Metab ; 303(4): E524-33, 2012 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-22693207

RESUMO

The Rab-GTPase-activating protein TBC1D1 has emerged as a novel candidate involved in metabolic regulation. Our aim was to determine whether TBC1D1 is involved in insulin as well as energy-sensing signals controlling skeletal muscle metabolism. TBC1D1-deficient congenic B6.SJL-Nob1.10 (Nob1.10(SJL)) and wild-type littermates were studied. Glucose and insulin tolerance, glucose utilization, hepatic glucose production, and tissue-specific insulin-mediated glucose uptake were determined. The effect of insulin, AICAR, or contraction on glucose transport was studied in isolated skeletal muscle. Glucose and insulin tolerance tests were normal in TBC1D1-deficient Nob1.10(SJL) mice, yet the 4-h-fasted insulin concentration was increased. Insulin-stimulated peripheral glucose utilization during a euglycemic hyperinsulinemic clamp was similar between genotypes, whereas the suppression of hepatic glucose production was increased in TBC1D1-deficient mice. In isolated extensor digitorum longus (EDL) but not soleus muscle, glucose transport in response to insulin, AICAR, or contraction was impaired by TBC1D1 deficiency. The reduction in glucose transport in EDL muscle from TBC1D1-deficient Nob1.10(SJL) mice may be explained partly by a 50% reduction in GLUT4 protein, since proximal signaling at the level of Akt, AMPK, and acetyl-CoA carboxylase (ACC) was unaltered. Paradoxically, in vivo insulin-stimulated 2-deoxyglucose uptake was increased in EDL and tibialis anterior muscle from TBC1D1-deficient mice. In conclusion, TBC1D1 plays a role in regulation of glucose metabolism in skeletal muscle. Moreover, functional TBC1D1 is required for AICAR- or contraction-induced metabolic responses, implicating a role in energy-sensing signals.


Assuntos
Proteínas Ativadoras de GTPase/metabolismo , Glucose/metabolismo , Músculo Esquelético/metabolismo , Proteínas Nucleares/metabolismo , Aminoimidazol Carboxamida/análogos & derivados , Aminoimidazol Carboxamida/farmacologia , Animais , Transporte Biológico/efeitos dos fármacos , Desoxiglucose/metabolismo , Jejum/sangue , Jejum/metabolismo , Gluconeogênese/efeitos dos fármacos , Gluconeogênese/fisiologia , Teste de Tolerância a Glucose , Transportador de Glucose Tipo 4/análise , Hipoglicemiantes/farmacologia , Insulina/sangue , Insulina/farmacologia , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Camundongos , Contração Muscular/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Proteínas Nucleares/genética , Ribonucleotídeos/farmacologia , Transdução de Sinais/efeitos dos fármacos
18.
Diabetes ; 71(4): 624-636, 2022 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-35040927

RESUMO

Dysregulation of skeletal muscle metabolism influences whole-body insulin sensitivity and glucose homeostasis. We hypothesized that type 2 diabetes-associated alterations in the plasma metabolome directly contribute to skeletal muscle immunometabolism and the subsequent development of insulin resistance. To this end, we analyzed the plasma and skeletal muscle metabolite profile and identified glutamine as a key amino acid that correlates inversely with BMI and insulin resistance index (HOMA-IR) in men with normal glucose tolerance or type 2 diabetes. Using an in vitro model of human myotubes and an in vivo model of diet-induced obesity and insulin resistance in male mice, we provide evidence that glutamine levels directly influence the inflammatory response of skeletal muscle and regulate the expression of the adaptor protein GRB10, an inhibitor of insulin signaling. Moreover, we demonstrate that a systemic increase in glutamine levels in a mouse model of obesity improves insulin sensitivity and restores glucose homeostasis. We conclude that glutamine supplementation may represent a potential therapeutic strategy to prevent or delay the onset of insulin resistance in obesity by reducing inflammatory markers and promoting skeletal muscle insulin sensitivity.


Assuntos
Diabetes Mellitus Tipo 2 , Resistência à Insulina , Animais , Diabetes Mellitus Tipo 2/metabolismo , Glucose/metabolismo , Glutamina/metabolismo , Humanos , Insulina/metabolismo , Resistência à Insulina/fisiologia , Masculino , Camundongos , Músculo Esquelético/metabolismo , Obesidade/metabolismo
19.
Sci Adv ; 7(11)2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33712458

RESUMO

Increased levels of apolipoprotein CIII (apoCIII), a key regulator of lipid metabolism, result in obesity-related metabolic derangements. We investigated mechanistically whether lowering or preventing high-fat diet (HFD)-induced increase in apoCIII protects against the detrimental metabolic consequences. Mice, first fed HFD for 10 weeks and thereafter also given an antisense (ASO) to lower apoCIII, already showed reduced levels of apoCIII and metabolic improvements after 4 weeks, despite maintained obesity. Prolonged ASO treatment reversed the metabolic phenotype due to increased lipase activity and receptor-mediated hepatic uptake of lipids. Fatty acids were transferred to the ketogenic pathway, and ketones were used in brown adipose tissue (BAT). This resulted in no fat accumulation and preserved morphology and function of liver and BAT. If ASO treatment started simultaneously with the HFD, mice remained lean and metabolically healthy. Thus, lowering apoCIII protects against and reverses the HFD-induced metabolic phenotype by promoting physiological insulin sensitivity.


Assuntos
Dieta Hiperlipídica , Doenças Metabólicas , Tecido Adiposo Marrom/metabolismo , Animais , Apolipoproteína C-III/metabolismo , Dieta Hiperlipídica/efeitos adversos , Doenças Metabólicas/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Obesidade/etiologia , Obesidade/metabolismo , Obesidade/prevenção & controle
20.
J Clin Invest ; 117(5): 1354-60, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17415414

RESUMO

The adipose-derived hormone, leptin, acts via its receptor (LRb) to convey the status of body energy stores to the brain, decreasing feeding and potentiating neuroendocrine energy expenditure. The failure of high levels of leptin in most obese individuals to promote weight loss defines a state of diminished responsiveness to increased leptin, termed leptin resistance. Leptin stimulates the phosphorylation of several tyrosine residues on LRb to mediate leptin action. We homologously replaced LRb in mice with a receptor with a mutation in one of these sites (Tyr985) in order to examine its role in leptin action and signal attenuation in vivo. Mice homozygous for this mutation are neuroendocrinologically normal, but females demonstrate decreased feeding, decreased expression of orexigenic neuropeptides, protection from high-fat diet-induced obesity, and increased leptin sensitivity in a sex-biased manner. Thus, leptin activates autoinhibitory signals via LRb Tyr985 to attenuate the anti-adiposity effects of leptin, especially in females, potentially contributing to leptin insensitivity in obesity.


Assuntos
Sistema Endócrino/fisiologia , Receptores de Superfície Celular/deficiência , Receptores de Superfície Celular/fisiologia , Transdução de Sinais/genética , Magreza/genética , Magreza/metabolismo , Substituição de Aminoácidos/genética , Animais , Feminino , Leptina/antagonistas & inibidores , Leptina/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Obesidade/genética , Obesidade/metabolismo , Obesidade/fisiopatologia , Receptores de Superfície Celular/antagonistas & inibidores , Receptores de Superfície Celular/genética , Receptores para Leptina , Sensibilidade e Especificidade , Fatores Sexuais , Magreza/fisiopatologia , Tirosina/genética
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