RESUMO
Purpose in life is critical to positive development among youth, especially those purposes that focus on an aspect of the world beyond the self. However, existing instruments have not adequately assessed beyond-the-self purpose. The Claremont Purpose Scale addresses the purpose construct, measuring the goal orientation, personal meaningfulness, and beyond-the-self focus among youth in the United States. We developed a version of the scale for use in the Chinese context among youth. In our two-part study, Study 1 developed the preliminary scale, and Study 2 evaluated its validity and reliability. The results indicated this scale is valuable for the assessment of the purpose of Chinese youth, has theoretical and practical implications for the measurement of beyond-the-self purpose, and can contribute to Chinese youth purpose research and future cross-cultural studies.
Assuntos
Comparação Transcultural , População do Leste Asiático , Humanos , Adolescente , Psicometria , Reprodutibilidade dos Testes , Povo Asiático , Inquéritos e Questionários , ChinaRESUMO
Insulin resistance is a major risk factor for many diseases. However, its underlying mechanism remains unclear in part because it is triggered by a complex relationship between multiple factors, including genes and the environment. Here, we used metabolomics combined with computational methods to identify factors that classified insulin resistance across individual mice derived from three different mouse strains fed two different diets. Three inbred ILSXISS strains were fed high-fat or chow diets and subjected to metabolic phenotyping and metabolomics analysis of skeletal muscle. There was significant metabolic heterogeneity between strains, diets, and individual animals. Distinct metabolites were changed with insulin resistance, diet, and between strains. Computational analysis revealed 113 metabolites that were correlated with metabolic phenotypes. Using these 113 metabolites, combined with machine learning to segregate mice based on insulin sensitivity, we identified C22:1-CoA, C2-carnitine, and C16-ceramide as the best classifiers. Strikingly, when these three metabolites were combined into one signature, they classified mice based on insulin sensitivity more accurately than each metabolite on its own or other published metabolic signatures. Furthermore, C22:1-CoA was 2.3-fold higher in insulin-resistant mice and correlated significantly with insulin resistance. We have identified a metabolomic signature composed of three functionally unrelated metabolites that accurately predicts whole-body insulin sensitivity across three mouse strains. These data indicate the power of simultaneous analysis of individual, genetic, and environmental variance in mice for identifying novel factors that accurately predict metabolic phenotypes like whole-body insulin sensitivity.
Assuntos
Biologia Computacional/métodos , Dieta , Resistência à Insulina/fisiologia , Metaboloma , Metabolômica/métodos , Animais , Masculino , Camundongos , Camundongos EndogâmicosRESUMO
The present study investigated the efficacy of the hepatoprotective drug matrine (Mtr) for its new application for hepatosteatosis and associated disorders in glucose homeostasis. The study was performed in two nutritional models of hepatosteatosis in mice with various abnormal glucose homeostasis: (1) high-fructose diet (HFru) induced hepatosteatosis and glucose intolerance from hepatic, and (2) hepatosteatosis and hyperglycemia induced by high-fat (HF) diet in combination with low doses of streptozotocin (STZ). Administration of Mtr (100 mg/kg every day in diet for 4 weeks) abolished HFru-induced hepatosteatosis and glucose intolerance. These effects were associated with the inhibition of HFru-stimulated de novo lipogenesis (DNL) without altering hepatic fatty acid oxidation. Further investigation revealed that HFru-induced endoplasmic reticulum (ER) stress was inhibited, whereas heat-shock protein 72 (an inducible chaperon protein) was increased by Mtr. In a type 2 diabetic model induced by HF-STZ, Mtr reduced hepatosteatosis and improved attenuated hyperglycemia. The hepatoprotective drug Mtr may be repurposed for the treatment of hepatosteatosis and associated disorders in glucose homeostasis. The inhibition of ER stress associated DNL and fatty acid influx appears to play an important role in these metabolic effects.
Assuntos
Alcaloides/uso terapêutico , Reposicionamento de Medicamentos , Fígado Gorduroso/tratamento farmacológico , Intolerância à Glucose/tratamento farmacológico , Substâncias Protetoras/uso terapêutico , Quinolizinas/uso terapêutico , Adiposidade/efeitos dos fármacos , Animais , Peso Corporal/efeitos dos fármacos , Dieta Hiperlipídica/efeitos adversos , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Ácidos Graxos/metabolismo , Frutose/efeitos adversos , Frutose/metabolismo , Proteínas de Choque Térmico HSP72/metabolismo , Homeostase/efeitos dos fármacos , Lipogênese/efeitos dos fármacos , Fígado/fisiopatologia , Camundongos Endogâmicos C57BL , Triglicerídeos/metabolismo , MatrinasRESUMO
The accumulation of unfolded proteins within the endoplasmic reticulum (ER) causes ER stress and activation of unfolded protein response (UPR). This response can trigger ER-associated degradation and autophagy, which clear unfolded proteins and restore protein homeostasis. Recently, it has become clear that ubiquitination plays an important role in the regulation of autophagy. In the present study, we investigated how the E3 ubiquitin ligase neural precursor cell-expressed, developmentally down-regulated protein 4-2 (Nedd4-2) interacts with ER stress and autophagy. In mice, we found that an increase in the expression of Nedd4-2, which was concomitant with the activation of the UPR and autophagy, was caused by a prolonged high-fructose and high-fat diet that induces ER stress in the liver. Pharmacologic induction of ER stress also led to an increase in Nedd4-2 expression in cultured cells, which was coincident with UPR and autophagy activation. The inhibition of inositol-requiring enzyme 1 significantly suppressed Nedd4-2 expression. Moreover, increased Nedd4-2 expression in vivo was closely associated with the activation of inositol-requiring enzyme 1 and increased expression of the spliced form of X-box binding protein 1. Furthermore, knockdown of Nedd4-2 in cultured cells suppressed both basal autophagy and ER stress-induced autophagy, whereas overexpression of Nedd4-2-induced autophagy. Taken together, our findings provide evidence that Nedd4-2 is up-regulated in response to ER stress by the spliced form of X-box binding protein 1 and that this is important in the induction of an appropriate autophagic response.-Wang, H. Sun, R.-Q., Camera, D., Zeng, X.-Y., Jo, E., Chan, S. M. H., Herbert, T. P., Molero, J. C., Ye, J.-M. Endoplasmic reticulum stress up-regulates Nedd4-2 to induce autophagy.
Assuntos
Autofagia/fisiologia , Retículo Endoplasmático/fisiologia , Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Regulação da Expressão Gênica/fisiologia , Ubiquitina-Proteína Ligases/metabolismo , Regulação para Cima/fisiologia , Animais , Complexos Endossomais de Distribuição Requeridos para Transporte/genética , Fibroblastos/metabolismo , Células HEK293 , Células HeLa , Humanos , Fígado/metabolismo , Masculino , Camundongos , Ubiquitina-Proteína Ligases Nedd4 , Ubiquitina-Proteína Ligases/genética , Proteína 1 de Ligação a X-Box/genética , Proteína 1 de Ligação a X-Box/metabolismoRESUMO
The unfolded protein response (UPR) pathways have been implicated in the development of hepatic insulin resistance during high fructose (HFru) feeding. The present study investigated their roles in initiating impaired insulin signaling transduction in the liver induced by HFru feeding in mice. HFru feeding resulted in hepatic steatosis, increased de novo lipogenesis and activation of two arms of the UPR pathways (IRE1/XBP1 and PERK/eIF2α) in similar patterns from 3days to 8weeks. In order to identify the earliest trigger of impaired insulin signaling in the liver, we fed mice a HFru diet for one day and revealed that only the IRE1 branch was activated (by 2-fold) and insulin-mediated Akt phosphorylation was blunted (~25%) in the liver. There were significant increases in phosphorylation of JNK (~50%) and IRS at serine site (~50%), protein content of ACC and FAS (up to 2.5-fold) and triglyceride level (2-fold) in liver (but not in muscle or fat). Blocking IRE1 activity abolished increases in JNK activity, IRS serine phosphorylation and protected insulin-stimulated Akt phosphorylation without altering hepatic steatosis or PKCε activity, a key link between lipids and insulin resistance. Our findings together suggest that activation of IRE1-JNK pathway is a key linker of impaired hepatic insulin signaling transduction induced by HFru feeding.
Assuntos
Frutose/administração & dosagem , Frutose/metabolismo , Insulina/metabolismo , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Proteínas de Membrana/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Transdução de Sinais/fisiologia , Triglicerídeos/metabolismo , Animais , Resistência à Insulina , Masculino , Proteínas de Membrana/genética , Camundongos , Camundongos Endogâmicos C57BL , Proteínas Serina-Treonina Quinases/genética , Resposta a Proteínas não DobradasRESUMO
Hepatic steatosis is often associated with insulin resistance as a hallmark of the metabolic syndrome in the liver. The present study investigated the effects of PPARα activation induced by fenofibrate (FB) on the relationship of insulin resistance and hepatic steatosis in mice fed a high-fat (HF) diet, which increases lipid influx into the liver. Mice were fed HF diet to induce insulin resistance and hepatic steatosis with or without FB. FB activated PPARα and ameliorated HF diet-induced glucose intolerance and hepatic insulin resistance without altering either hepatic steatosis or inflammation signaling (JNK or IKK). Interestingly, FB treatment simultaneously increased fatty acid (FA) synthesis (50%) and oxidation (66%, both p<0.01) into intermediate lipid metabolites, suggesting a FA oxidation-synthesis cycling in operation. Associated with these effects, diacylglycerols (DAGs) were sequestered within the lipid droplet/ER compartment, thus reducing their deposition in the cellular membrane, which is known to impair insulin signal transduction. These findings suggest that the reduction in membrane DAGs (rather than total hepatic steatosis) may be critical for the protection by fenofibrate-induced PPARα activation against hepatic insulin resistance induced by dietary fat.
Assuntos
Diglicerídeos/metabolismo , Retículo Endoplasmático/metabolismo , Fígado Gorduroso/metabolismo , Fenofibrato/farmacologia , Hipolipemiantes/farmacologia , Insulina/metabolismo , Gotículas Lipídicas/metabolismo , Animais , Dieta Hiperlipídica/efeitos adversos , Retículo Endoplasmático/efeitos dos fármacos , Fígado Gorduroso/etiologia , Gotículas Lipídicas/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Fígado/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , PPAR alfa/metabolismo , Transdução de SinaisRESUMO
Glycogen is a vital highly branched polymer of glucose that is essential for blood glucose homeostasis. In this article, the structure of liver glycogen from mice is investigated with respect to size distributions, degradation kinetics, and branching structure, complemented by a comparison of normal and diabetic liver glycogen. This is done to screen for differences that may result from disease. Glycogen α-particle (diameter â¼ 150 nm) and ß-particle (diameter â¼ 25 nm) size distributions are reported, along with in vitro γ-amylase degradation experiments, and a small angle X-ray scattering analysis of mouse ß-particles. Type 2 diabetic liver glycogen upon extraction was found to be present as large loosely bound, aggregates, not present in normal livers. Liver glycogen was found to aggregate in vitro over a period of 20 h, and particle size is shown to be related to rate of glucose release, allowing a structure-function relationship to be inferred for the tissue specific distribution of particle types. Application of branching theories to small angle X-ray scattering data for mouse ß-particles revealed these particles to be randomly branched polymers, not fractal polymers. Together, this article shows that type 2 diabetic liver glycogen is present as large aggregates in mice, which may contribute to the inflexibility of interconversion between glucose and glycogen in type 2 diabetes, and further that glycogen particles are randomly branched with a size that is related to the rate of glucose release.
Assuntos
Diabetes Mellitus Tipo 2/metabolismo , Glucose/metabolismo , Glicogênio/química , Fígado/metabolismo , Animais , Glicogênio/metabolismo , CamundongosRESUMO
OBJECTIVES: To meet the demand for personalized treatment, effective stratification of patients with metastatic nasopharyngeal carcinoma (mNPC) is essential. Hence, our study aimed to establish an M1 subdivision for prognostic prediction and treatment planning in patients with mNPC. MATERIALS AND METHODS: This study included 1239 patients with mNPC from three medical centers divided into the synchronous mNPC cohort (smNPC, n = 556) to establish an M1 stage subdivision and the metachronous mNPC cohort (mmNPC, n = 683) to validate this subdivision. The primary endpoint was overall survival. Univariate and multivariate Cox analyses identified covariates for the decision-tree model, proposing an M1 subdivision. Model performance was evaluated using time-dependent receiver operating characteristic curves, Harrell's concordance index, calibration plots, and decision curve analyses. RESULTS: The proposed M1 subdivisions were M1a (≤5 metastatic lesions), M1b (>5 metastatic lesions + absent liver metastases), and M1c (>5 metastatic lesions + existing liver metastases) with median OS of 34, 22, and 13 months, respectively (p < 0.001). This M1 subdivision demonstrated superior discrimination (C-index = 0.698; 3-year AUC = 0.707) and clinical utility over those of existing staging systems. Calibration curves exhibited satisfactory agreement between predictions and actual observations. Internal and mmNPC cohort validation confirmed the robustness. Survival benefits from local metastatic treatment were observed in M1a, while immunotherapy improved survival in patients with M1b and M1c disease. CONCLUSION: This novel M1 staging strategy provides a refined approach for prognostic prediction and treatment planning in patients with mNPC, emphasizing the potential benefits of local and immunotherapeutic interventions based on individualized risk stratification.
Assuntos
Árvores de Decisões , Carcinoma Nasofaríngeo , Humanos , Masculino , Feminino , Pessoa de Meia-Idade , Carcinoma Nasofaríngeo/patologia , Carcinoma Nasofaríngeo/mortalidade , Carcinoma Nasofaríngeo/terapia , Estudos Retrospectivos , Adulto , Estadiamento de Neoplasias , Neoplasias Nasofaríngeas/patologia , Neoplasias Nasofaríngeas/terapia , Neoplasias Nasofaríngeas/mortalidade , Prognóstico , IdosoRESUMO
OBJECTIVE: We investigated the efficacy of metastatic lesion radiotherapy (MLRT) in patients with metastatic nasopharyngeal carcinoma (mNPC). MATERIALS AND METHODS: Patients with mNPC from three institutions were included in this study. Propensity score matching (PSM) was employed to ensure comparability between patient groups. Overall survival (OS) rates were assessed using the Kaplan-Meier method and compared using the log-rank test. Prognostic factors were identified using univariate and multivariate Cox hazard analyses. Subgroup analyses were conducted to assess the effects of MLRT on specific patient populations. RESULTS: We analyzed data from 1157 patients with mNPC. Patients who received MLRT had significantly better OS than those who did not, both in the original (28 vs. 21 months) and PSM cohorts (26 vs. 23 months). MLRT was identified as an independent favorable predictor of OS in multivariate analyses, with hazard ratios of 0.67. The subgroup analysis results indicated that radiotherapy effectively treated liver, lung, and bone metastatic lesions, particularly in patients with a limited tumor burden. Higher total radiation doses of MLRT (biologically effective dose (BED) ≥ 56 Gy) were associated with improved OS, while neither radiation technique nor dose fractionation independently influenced prognosis. CONCLUSIONS: MLRT offers survival advantages to patients diagnosed with mNPC. Patients with limited metastatic burden derive the most benefit from MLRT, and the recommended regimen for MLRT is a minimum BED of 56 Gy for optimal outcomes.
Assuntos
Carcinoma , Carcinoma Nasofaríngeo , Neoplasias Nasofaríngeas , Humanos , Masculino , Feminino , Estudos Retrospectivos , Pessoa de Meia-Idade , Neoplasias Nasofaríngeas/radioterapia , Neoplasias Nasofaríngeas/patologia , Neoplasias Nasofaríngeas/mortalidade , Carcinoma Nasofaríngeo/radioterapia , Carcinoma Nasofaríngeo/patologia , Carcinoma Nasofaríngeo/mortalidade , Carcinoma/radioterapia , Carcinoma/secundário , Carcinoma/mortalidade , Adulto , Idoso , Pontuação de Propensão , Prognóstico , Taxa de Sobrevida , Neoplasias Ósseas/secundário , Neoplasias Ósseas/radioterapia , Neoplasias Ósseas/mortalidade , Neoplasias Pulmonares/radioterapia , Neoplasias Pulmonares/patologia , Neoplasias Pulmonares/mortalidade , Resultado do Tratamento , Neoplasias Hepáticas/secundário , Neoplasias Hepáticas/radioterapia , Neoplasias Hepáticas/mortalidadeRESUMO
Albiflorin (AF) is a small molecule (MW 481) isolated from Paeoniae radix, a plant used as a remedy for various conditions with pathogenesis shared by metabolic diseases. Reported here is our characterization of its therapeutic profiles in three mouse models with distinctive pathological features of metabolic syndrome (MetS). Our results firstly showed that AF alleviated high fat (HF) induced obesity and associated glucose intolerance, suggesting its therapeutic efficacy for MetS. In the type 2 diabetes (T2D) model induced by a combination of HF and low doses of streptozotocin, AF lowered hyperglycaemia and improved insulin-stimulated glucose disposal. In the non-alcoholic steatohepatitis-like model resulting from a HF and high cholesterol (HF-HC) diet, AF reversed the increased liver triglyceride and cholesterol, plasma aspartate aminotransferase, and liver TNFα mRNA levels. Consistent with its effect in promoting glucose disposal in HF-fed mice, AF stimulated glucose uptake and GLUT4 translocation to the plasma membrane in L6 myotubes. However, these effects were unlikely to be associated with activation of insulin, AMPK, ER, or cellular stress signalling cascades. Further studies revealed that AF increased the whole-body energy expenditure and physical activity. Taken together, our findings indicate that AF exerts a therapeutic potential for MetS and related diseases possibly by promoting physical activity associated whole-body energy expenditure and glucose uptake in muscle. These effects are possibly mediated by a new mechanism distinct from other therapeutics derived from Chinese medicine.
RESUMO
Research into cellular metabolism has become more high-throughput, with typical cell-culture experiments being performed in multiwell plates (microplates). This format presents a challenge when trying to collect gaseous products, such as carbon dioxide (CO2), which requires a sealed environment and a vessel separate from the biological sample. To address this limitation, we developed a gas trapping protocol using perforated plastic lids in sealed cell-culture multiwell plates. We used this trap design to measure CO2 production from glucose and fatty acid metabolism, as well as hydrogen sulfide production from cysteine-treated cells. Our data clearly show that this gas trap can be applied to liquid and solid gas-collection media and can be used to study gaseous product generation by both adherent cells and cells in suspension. Since our gas traps can be adapted to multiwell plates of various sizes, they present a convenient, cost-effective solution that can accommodate the trend toward high-throughput measurements in metabolic research.
Assuntos
Adipócitos/metabolismo , Dióxido de Carbono/metabolismo , Técnicas de Cultura de Células/instrumentação , Sulfeto de Hidrogênio/metabolismo , Células 3T3-L1 , Animais , Técnicas de Cultura de Células/economia , Técnicas de Cultura de Células/métodos , Cisteína/metabolismo , Desenho de Equipamento , Ácidos Graxos/metabolismo , Glucose/metabolismo , Metabolômica/economia , Metabolômica/instrumentação , Metabolômica/métodos , CamundongosRESUMO
BACKGROUND: Recent studies have concluded that the carbohydrate content and glycemic index (GI) of individual foods do not predict the glycemic and insulinemic effects of mixed meals. We hypothesized that these conclusions may be unwarranted because of methodologic considerations. OBJECTIVE: The aim was to ascertain whether the GI and carbohydrate content of individual foods influence glucose and insulin responses elicited by realistic mixed meals in normal subjects. DESIGN: With the use of a crossover design, we determined the glucose and insulin responses of 6 test meals in 16 subjects in Sydney and the glucose responses of 8 test meals in 10 subjects in Toronto and then the results were pooled. The 14 different test meals varied in energy (220-450 kcal), protein (0-18 g), fat (0-18 g), and available carbohydrate (16-79 g) content and in GI (35-100; values were rounded). RESULTS: The glucose and insulin responses of the Sydney test meals varied over a 3-fold range (P < 0.001), and the glucose responses of the Toronto test meals varied over a 2.4-fold range (P < 0.001). The glucose responses were not related to the fat or protein content of the test meal. Carbohydrate content (P = 0.002) and GI (P = 0.022) alone were related to glucose responses; together they accounted for 88% of the variation in the glycemic response (P < 0.0001). The insulin response was significantly related to the glucose response (r = 0.94, P = 0.005). CONCLUSIONS: When properly applied in realistic settings, GI is a significant determinant of the glycemic effect of mixed meals in normal subjects. For mixed meals within the broad range of nutrient composition that we tested, carbohydrate content and GI together explained approximately 90% of the variation in the mean glycemic response, with protein and fat having negligible effects.
Assuntos
Carboidratos da Dieta/farmacologia , Índice Glicêmico/efeitos dos fármacos , Insulina/sangue , Adulto , Área Sob a Curva , Austrália , Estudos Transversais , Carboidratos da Dieta/administração & dosagem , Carboidratos da Dieta/análise , Ingestão de Energia , Feminino , Análise de Alimentos , Humanos , Masculino , OntárioRESUMO
Despite major investment by pharmaceutical companies in conventional drug discovery pipelines, development of new drugs has failed to keep up with the increasing incidence of many diseases, including type 2 diabetes (T2D). Drug repurposing, where existing drugs are applied to a new indication, is gaining momentum as a successful approach to overcome the bottlenecks commonly encountered with conventional approaches. Repurposing takes advantage of available information on the molecular pharmacology of clinical agents to drastically shorten drug development timelines. This review discusses recent advances in the discovery of new antidiabetic agents using repurposing strategies.
Assuntos
Diabetes Mellitus Tipo 2/tratamento farmacológico , Reposicionamento de Medicamentos/métodos , Hipoglicemiantes/uso terapêutico , Animais , Diabetes Mellitus Tipo 2/epidemiologia , Epidemias , Humanos , Hipoglicemiantes/farmacologiaRESUMO
The present study investigated the role of dietary cholesterol and fat in the development of nonalcoholic fatty liver disease, a common liver disease in metabolic disorders. Mice were fed a diet of regular chow (CH), chow supplemented with 0.2% w/w cholesterol (CHC), high fat (HF, 45kcal%) or HF with cholesterol (HFC) for 17weeks. While both HF and HFC groups displayed hepatic steatosis and metabolic syndrome, only HFC group developed the phenotype of liver injury, as indicated by an increase in plasma level of alanine transaminase (ALT, by 50-80%). There were ~2-fold increases in mRNA expression of tumor necrosis factor α, interleukin 1ß and monocyte chemotactic protein 1 in the liver of HFC-fed mice (vs. HF) but no endoplasmic reticulum stress or oxidative stress was observed. Furthermore, cholesterol suppressed HF-induced increase of peroxisome proliferator-activated receptor γ coactivator 1α and mitochondrial transcription factor A expression and blunted fatty acid oxidation. Interestingly, after switching HFC to HF diet for 5weeks, the increases in plasma ALT and liver inflammatory markers were abolished but the blunted of mitochondrial function remained. These findings suggest that cholesterol plays a critical role in the conversion of a simple fatty liver toward nonalcoholic steatohepatitis possibly by activation of inflammatory pathways together with retarded mitochondrial function.
Assuntos
Colesterol na Dieta , Dieta Hiperlipídica , Mitocôndrias Hepáticas/fisiologia , Hepatopatia Gordurosa não Alcoólica/fisiopatologia , Animais , Camundongos , OxirreduçãoRESUMO
High-carbohydrate (mainly fructose) consumption is a major dietary factor for hepatic insulin resistance, involving endoplasmic reticulum (ER) stress and lipid accumulation. Because autophagy has been implicated in ER stress, the present study investigated the role of autophagy in high-fructose (HFru) diet-induced hepatic ER stress and insulin resistance in male C57BL/6J mice. The results show that chronic HFru feeding induced glucose intolerance and impaired insulin signaling transduction in the liver, associated with ER stress and the accumulation of lipids. Intriguingly, hepatic autophagy was suppressed as a result of activation of mammalian target of rapamycin. The suppressed autophagy was detected within 6 hours after HFru feeding along with activation of both inositol-requiring enzyme 1 and protein kinase RNA-like endoplasmic reticulum kinase pathways. These events occurred prior to lipid accumulation or lipogenesis and were sufficient to blunt insulin signaling transduction with activation of c-Jun N-terminal kinase/inhibitory-κB kinase and serine phosphorylation of insulin receptor substrate 1. The stimulation of autophagy attenuated ER stress- and c-Jun N-terminal kinase/inhibitory-κB kinase-associated impairment in insulin signaling transduction in a mammalian target of rapamycin -independent manner. Taken together, our data suggest that restoration of autophagy functions disrupted by fructose is able to alleviate ER stress and improve insulin signaling transduction.
Assuntos
Autofagia , Retículo Endoplasmático/fisiologia , Frutose/toxicidade , Insulina/metabolismo , Fígado/fisiologia , Estresse Fisiológico/fisiologia , Animais , Carboidratos da Dieta/toxicidade , Intolerância à Glucose , Lipogênese , Fígado/efeitos dos fármacos , MAP Quinase Quinase 4 , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Músculo Esquelético , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Serina-Treonina Quinases TOR/genética , Serina-Treonina Quinases TOR/metabolismoRESUMO
BACKGROUND AND PURPOSE: Matrine is a small molecule drug used in humans for the treatment of chronic viral infections and tumours in the liver with little adverse effects. The present study investigated its therapeutic efficacy for insulin resistance and hepatic steatosis in high-fat-fed mice. EXPERIMENTAL APPROACH: C57BL/J6 mice were fed a chow or high-fat diet for 10 weeks and then treated with matrine or metformin for 4 weeks. The effects on lipid metabolism and glucose tolerance were evaluated. KEY RESULTS: Our results first showed that matrine reduced glucose intolerance and plasma insulin level, hepatic triglyceride content and adiposity in high-fat-fed mice without affecting caloric intake. This reduction in hepatosteatosis was attributed to suppressed lipid synthesis and increased fatty acid oxidation. In contrast to metformin, matrine neither suppressed mitochondrial respiration nor activated AMPK in the liver. A computational docking simulation revealed HSP90, a negative regulator of HSP72, as a potential binding target of matrine. Consistent with the simulation results, matrine, but not metformin, increased the hepatic protein level of HSP72 and this effect was inversely correlated with both liver triglyceride level and glucose intolerance. CONCLUSIONS AND IMPLICATIONS: Taken together, these results indicate that matrine may be used for the treatment of type 2 diabetes and hepatic steatosis, and the molecular action of this hepatoprotective drug involves the activation of HSP72 in the liver.
Assuntos
Alcaloides/administração & dosagem , Sistemas de Liberação de Medicamentos/tendências , Fígado Gorduroso/tratamento farmacológico , Intolerância à Glucose/tratamento farmacológico , Proteínas de Choque Térmico HSP72/agonistas , Quinolizinas/administração & dosagem , Alcaloides/metabolismo , Animais , Dieta Hiperlipídica/efeitos adversos , Fígado Gorduroso/etiologia , Fígado Gorduroso/metabolismo , Intolerância à Glucose/metabolismo , Proteínas de Choque Térmico HSP72/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Quinolizinas/metabolismo , MatrinasRESUMO
Our recent study (referred as Study 1) showed that the triterpenoid oleanolic acid (OA) was able to produce a sustained correction of hyperglycemia beyond treatment period in type 2 diabetes (T2D) mice with liver as a responsible site. To follow up the previous observations, the present study (referred as Study 2) investigated the possible role of acetylation of FoxO1 and associated events in this therapeutic memory by characterizing the pathways regulating the acetylation status during and post-OA treatments. OA treatment (100 mg/kg/day for 4 weeks, during OA treatment) reduced hyperglycemia in T2D mice by â¼87% and this effect was largely (â¼70%) maintained even 4 weeks after the cessation of OA administration (post-OA treatment). During OA treatment, the acetylation and phosphorylation of FoxO1 were markedly increased (1.5 to 2.5-fold) while G6Pase expression was suppressed by â¼80%. Consistent with this, OA treatment reversed pyruvate intolerance in high-fat fed mice. Histone acetyltransferase 1 (HAT1) content was increased (>50%) and histone deacetylases (HDACs) 4 and 5 (not HDAC1) were reduced by 30-50%. The OA-induced changes in FoxO1, G6Pase, HAT1 and HDACs persisted during the post-OA treatment period when the increased phosphorylation of AMPK, SIRT1 content and reduced liver triglyceride had subsided. These results confirmed the ability of OA to control hyperglycemia far beyond treatment period in T2D mice. Most importantly, in the present study we demonstrated acetylation of FoxO1 in the liver is involved in OA-induced memory for the control of hyperglycemia. Our novel findings suggest that acetylation of the key regulatory proteins of hepatic gluconeogenesis is a plausible mechanism by the triterpenoid to achieve a sustained glycemic control for T2D.
Assuntos
Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/metabolismo , Fatores de Transcrição Forkhead/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Ácido Oleanólico/uso terapêutico , Proteínas Quinases Ativadas por AMP/metabolismo , Acetilação/efeitos dos fármacos , Animais , Glicemia/efeitos dos fármacos , Proteína Forkhead Box O1 , Fatores de Transcrição Forkhead/genética , Histona Acetiltransferases/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fosforilação/efeitos dos fármacos , Sirtuína 1/metabolismoRESUMO
Neonatal obesity predisposes individuals to obesity throughout life. In rats, neonatal overfeeding also leads to early accelerated weight gain that persists into adulthood. The phenotype is associated with dysfunction in a number of systems including paraventricular nucleus of the hypothalamus (PVN) responses to psychological and immune stressors. However, in many cases weight gain in neonatally overfed rats stabilizes in early adulthood so the animal does not become more obese as it ages. Here we examined if neonatal overfeeding by suckling rats in small litters predisposes them to exacerbated metabolic and central inflammatory disturbances if they are also given a high fat diet in later life. In adulthood we gave the rats normal chow, 3 days, or 3 weeks high fat diet (45% kcal from fat) and measured peripheral indices of metabolic disturbance. We also investigated hypothalamic microglial changes, as an index of central inflammation, as well as PVN responses to lipopolysaccharide (LPS). Surprisingly, neonatal overfeeding did not predispose rats to the metabolic effects of a high fat diet. Weight changes and glucose metabolism were unaffected by the early life experience. However, short term (3 day) high fat diet was associated with more microglia in the hypothalamus and a markedly exacerbated PVN response to LPS in control rats; effects not seen in the neonatally overfed. Our findings indicate neonatally overfed animals are not more susceptible to the adverse metabolic effects of a short-term high fat diet but may be less able to respond to the central effects.
RESUMO
Endoplasmic reticulum (ER) stress is suggested to cause hepatic insulin resistance by increasing de novo lipogenesis (DNL) and directly interfering with insulin signaling through the activation of the c-Jun N-terminal kinase (JNK) and IκB kinase (IKK) pathway. The current study interrogated these two proposed mechanisms in a mouse model of hepatic insulin resistance induced by a high fructose (HFru) diet with the treatment of fenofibrate (FB) 100 mg/kg/day, a peroxisome proliferator-activated receptor α (PPARα) agonist known to reduce lipid accumulation while maintaining elevated DNL in the liver. FB administration completely corrected HFru-induced glucose intolerance, hepatic steatosis, and the impaired hepatic insulin signaling (pAkt and pGSK3ß). Of note, both the IRE1/XBP1 and PERK/eIF2α arms of unfolded protein response (UPR) signaling were activated. While retaining the elevated DNL (indicated by the upregulation of SREBP1c, ACC, FAS, and SCD1 and [3H]H2O incorporation into lipids), FB treatment markedly increased fatty acid oxidation (indicated by induction of ACOX1, p-ACC, ß-HAD activity, and [14C]palmitate oxidation) and eliminated the accumulation of diacylglycerols (DAGs), which is known to have an impact on insulin signaling. Despite the marked activation of UPR signaling, neither JNK nor IKK appeared to be activated. These findings suggest that lipid accumulation (mainly DAGs), rather than the activation of JNK or IKK, is pivotal for ER stress to cause hepatic insulin resistance. Therefore, by reducing the accumulation of deleterious lipids, activation of PPARα can ameliorate hepatic insulin resistance against increased ER stress.
Assuntos
Fígado Gorduroso/metabolismo , Frutose/farmacologia , Resistência à Insulina/fisiologia , Fígado/metabolismo , PPAR alfa/metabolismo , Animais , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Ácidos Graxos/metabolismo , Fígado Gorduroso/tratamento farmacológico , Fenofibrato/uso terapêutico , Fígado/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Obesity is characterized by expansion of adipose tissue, which results from an increase in adipocyte number (adipogenesis) and adipocyte size (lipogenesis). A reversal of these processes has been suggested to be a potential antiobetic therapy. Rutaecarpine (Rut) and its novel analogues (R17 and R18) were identified to exert potent effect in reducing lipid accumulation during adipocyte differentiation in 3T3-L1 adipocytes with little cytotoxicity. All three compounds reduced lipid accumulation in a dose-dependent manner, while R17 and R18 exhibited much more potent inhibitory effects compared to that of Rut. Further studies showed that R17 suppressed both adipogenesis and lipogenesis during all stages of adipocyte differentiation as indicated by the reduced protein and mRNA levels of key regulators of adipogenesis/lipogenesis, including PPARγ, C/EBPα, SREBP-1c, ACC, FAS, and SCD-1. We next examined the effect of R17 on the UPR pathway and the results showed that the UPR markers (PERK, eIF2α, IRE1α, and spliced XBP1 mRNA) were all significantly reduced by R17. Further studies revealed that R17 persistently activated AMPK during differentiation, suggesting that the AMPK may be an upstream mechanism for the effect of R17 on adipogenesis and lipogenesis via the adipogenic/lipogenic markers and the UPR pathway. Finally, studies in fast/refeeding mice demonstrated that R17 administration was able to reduce epididymal fat mass and the levels of plasma TG and FFA in vivo. Our results suggest that rutaecarpine analogues may have therapeutic potential for obesity and related metabolic disorders. The mechanism involves the suppression of adipogenic/lipogenic proteins and the suppression of the UPR pathway possibly via the AMPK.