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1.
    
Clinical trials have shown that angiotensin II receptor blockers reduce the new onset of diabetes in hypertensives; however, the underlying mechanisms remain unknown. We investigated the effects of telmisartan on peroxisome proliferator activated receptor γ (PPAR‐δ) and the adenosine monophosphate (AMP)‐activated protein kinase (AMPK) pathway in cultured myotubes, as well as on the running endurance of wild‐type and PPAR‐δ‐deficient mice. Administration of telmisartan up‐regulated levels of PPAR‐δ and phospho‐AMPKα in cultured myotubes. However, PPAR‐δ gene deficiency completely abolished the telmisartan effect on phospho‐AMPKαin vitro. Chronic administration of telmisartan remarkably prevented weight gain, enhanced running endurance and post‐exercise oxygen consumption, and increased slow‐twitch skeletal muscle fibres in wild‐type mice, but these effects were absent in PPAR‐δ‐deficient mice. The mechanism is involved in PPAR‐δ‐mediated stimulation of the AMPK pathway. Compared to the control mice, phospho‐AMPKα level in skeletal muscle was up‐regulated in mice treated with telmisartan. In contrast, phospho‐AMPKα expression in skeletal muscle was unchanged in PPAR‐δ‐deficient mice treated with telmisartan. These findings highlight the ability of telmisartan to improve skeletal muscle function, and they implicate PPAR‐δ as a potential therapeutic target for the prevention of type 2 diabetes.  相似文献   

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Objective: Preclinical evaluation of DRF 2655, a peroxisome proliferator‐activated receptor alpha (PPARα) and PPARγ agonist, as a body‐weight lowering, hypolipidemic and euglycemic agent. Research Methods and Procedures: DRF 2655 was studied in different genetic, normal, and hyperlipidemic animal models. HEK 293 cells were used to conduct the reporter‐based transactivation of PPARα and PPARγ. To understand the biochemical mechanism of lipid‐, body‐weight‐, and glucose‐lowering effects, activities of key β‐oxidation and lipid catabolism enzymes and gluconeogenic enzymes were studied in db/db mice treated with DRF 2655. 3T3L1 cells were used for adipogenesis study, and HepG2 cells were used to study the effect of DRF 2655 on total cholesterol and triglyceride synthesis using [14C]acetate and [3H]glycerol. Results: DRF 2655 showed concentration‐dependent transactivation of PPARα and PPARγ. In the 3T3L1 cell‐differentiation study, DRF 2655 and rosiglitazone showed 369% and 471% increases, respectively, in triglyceride accumulation. DRF 2655 showed body‐weight lowering and euglycemic and hypolipidemic effects in various animal models. db/db mice treated with DRF 2655 showed 5‐ and 3.6‐fold inhibition in phosphoenolpyruvate carboxykinase and glucose 6‐phosphatase activity and 651% and 77% increases in the β‐oxidation enzymes carnitine palmitoyltransferase and carnitine acetyltransferase, respectively. HepG2 cells treated with DRF 2655 showed significant reduction in lipid synthesis. Discussion: DRF 2655 showed excellent euglycemic and hypolipidemic activities in different animal models. An exciting finding is its body‐weight lowering effect in these models, which might be mediated by the induction of target enzymes involved in hepatic lipid catabolism through PPARα activation.  相似文献   

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Mesenchymal stem cells (MSCs) provide us an excellent cellular model to uncover the molecular mechanisms underlying adipogenic differentiation of adult stem cells. PPARγ had been considered as an important molecular marker of cells undergoing adipogenic differentiation. Here, we demonstrated that expression and phosphorylation of PPARγ could be found in bone marrow–derived MSCs cultured in expansion medium without any adipogenic additives (dexamethasone, IBMX, insulin or indomethacin). Then, PPARγ was dephosphorylated in MSCs during the process of adipogenic differentiation. We then found that inhibition of MEK activation by specific inhibitor (PD98059) counteracted the PPARγ expression and phosphorylation. However, expression and phosphorylation of PPARγ did not present in MSCs cultured in medium with lower serum concentration. When these MSCs differentiated into adipocytes, no phosphorylation could be detected to accompany the expression of PPARγ. Moreover, exposure of MSCs to higher concentration of serum induced stronger PPARγ expression, and subsequently enhanced their adipogenesis. These data suggested that activation of the MEK/ERK signalling pathway by high serum concentration promoted PPARγ expression and phosphorylation, and subsequently enhanced adipogenic differentiation of MSCs.  相似文献   

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Yet unidentified variants within the peroxisome proliferator‐activated receptor γ (PPARγ) 2 promoter may explain the inconsistent reports on associations between variants in the coding region and obesity or diabetes. Thus, we examined the putative PPARγ2 promoter (?3371 to +43 bp) for variants in 83 subjects with obesity or type 2 diabetes. We identified eight variants, seven of which were novel, including ?792A>G, ?816C>T, ?882T>C, ?1505G>A, ?1881C>T, ?1884T>A, ?2604T>C, and ?2953A>G. The variants ?816C>T, ?1505G>A, ?1881C>T, and ?2604T>C were in total linkage disequilibrium, and there was a high degree of linkage disequilibrium between several of the novel variants and Pro12Ala. The novel variants were, together with Pro12Ala and 1431C>T, examined for relationships with obesity among 234 men with early‐onset obesity with a BMI at age ～20 years of 33.2 ± 2.5 kg/m2 and 323 nonobese men with a BMI of 21.7 ± 2.5 kg/m2, who were also reexamined after ～29 years. The prevalence of the identified variants was not significantly different between the two groups, and the variants did not affect changes in BMI over time. In conclusion, the identified novel variants in the PPARγ2 promoter region do not explain the reported discrepancies in the association of previously identified variants with obesity and type 2 diabetes.  相似文献   

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It has been recently reported that CD38 was highly expressed in adipose tissues from obese people and CD38‐deficient mice were resistant to high‐fat diet (HFD)‐induced obesity. However, the role of CD38 in the regulation of adipogenesis and lipogenesis is unknown. In this study, to explore the roles of CD38 in adipogenesis and lipogenesis in vivo and in vitro, obesity models were generated with male CD38?/? and WT mice fed with HFD. The adipocyte differentiations were induced with MEFs from WT and CD38?/? mice, 3T3‐L1 and C3H10T1/2 cells in vitro. The lipid accumulations and the alternations of CD38 and the genes involved in adipogenesis and lipogenesis were determined with the adipose tissues from the HFD‐fed mice or the MEFs, 3T3‐L1 and C3H10T1/2 cells during induction of adipocyte differentiation. The results showed that CD38?/? male mice were significantly resistant to HFD‐induced obesity. CD38 expressions in adipocytes were significantly increased in WT mice fed with HFD, and the similar results were obtained from WT MEFs, 3T3‐L1 and C3H10T1/2 during induction of adipocyte differentiation. The expressions of PPARγ, AP2 and C/EBPα were markedly attenuated in adipocytes from HFD‐fed CD38?/? mice and CD38?/? MEFs at late stage of adipocyte differentiation. Moreover, the expressions of SREBP1 and FASN were also significantly decreased in CD38?/? MEFs. Finally, the CD38 deficiency‐mediated activations of Sirt1 signalling were up‐regulated or down‐regulated by resveratrol and nicotinamide, respectively. These results suggest that CD38 deficiency impairs adipogenesis and lipogenesis through activating Sirt1/PPARγ‐FASN signalling pathway during the development of obesity.  相似文献   

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Microglia‐mediated neuroinflammation plays a dual role in various brain diseases due to distinct microglial phenotypes, including deleterious M1 and neuroprotective M2. There is growing evidence that the peroxisome proliferator‐activated receptor γ (PPARγ) agonist rosiglitazone prevents lipopolysaccharide (LPS)‐induced microglial activation. Here, we observed that antagonizing PPARγ promoted LPS‐stimulated changes in polarization from the M1 to the M2 phenotype in primary microglia. PPARγ antagonist T0070907 increased the expression of M2 markers, including CD206, IL‐4, IGF‐1, TGF‐β1, TGF‐β2, TGF‐β3, G‐CSF, and GM‐CSF, and reduced the expression of M1 markers, such as CD86, Cox‐2, iNOS, IL‐1β, IL‐6, TNF‐α, IFN‐γ, and CCL2, thereby inhibiting NFκB–IKKβ activation. Moreover, antagonizing PPARγ promoted microglial autophagy, as indicated by the downregulation of P62 and the upregulation of Beclin1, Atg5, and LC3‐II/LC3‐I, thereby enhancing the formation of autophagosomes and their degradation by lysosomes in microglia. Furthermore, we found that an increase in LKB1–STRAD–MO25 complex formation enhances autophagy. The LKB1 inhibitor radicicol or knocking down LKB1 prevented autophagy improvement and the M1‐to‐M2 phenotype shift by T0070907. Simultaneously, we found that knocking down PPARγ in BV2 microglial cells also activated LKB1–AMPK signaling and inhibited NFκB–IKKβ activation, which are similar to the effects of antagonizing PPARγ. Taken together, our findings demonstrate that antagonizing PPARγ promotes the M1‐to‐M2 phenotypic shift in LPS‐induced microglia, which might be due to improved autophagy via the activation of the LKB1–AMPK signaling pathway.  相似文献   

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Ulcerative colitis (UC) is a chronic gastrointestinal disorder interfering with life quality. A total of 60 male Wistar rats were divided into four equal groups: Control (group I), hesperidin only (group II), UC untreated (group III), and UC treated with hesperidin (group IV). Hesperidin had modulatory effects on UC pathogenesis, which might be through alleviating colonic sphingosine phosphate phosphatase 2 messenger RNA expression and sphingosine kinase‐1 levels, thus suppressing the subsequent downstream inflammatory and apoptotic cascades represented by decreased macrophage inflammatory protein‐1α and enhancement of B‐cell lymphoma 2 immunohistochemistry expression. Also, it improved mitochondrial biogenesis by increasing the peroxisome proliferator‐activated receptor‐gamma‐coactivator 1‐α level. It successfully restored redox potential as evidenced by marked alleviations of the nitric oxide and peroxynitrite levels, increasing total antioxidant capacity, and activating the superoxide dismutase enzyme. Also, hesperidin alleviated the UC disease activity index and improved the histopathological picture. These findings may offer a new therapeutic strategy for UC treatment.  相似文献   

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Short‐chain acyl‐CoA dehydrogenase (SCAD), a key enzyme of fatty acid β‐oxidation, plays an important role in cardiac hypertrophy. However, its effect on the cardiomyocyte apoptosis remains unknown. We aimed to determine the role of SCAD in tert‐butyl hydroperoxide (tBHP)‐induced cardiomyocyte apoptosis. The mRNA and protein expression of SCAD were significantly down‐regulated in the cardiomyocyte apoptosis model. Inhibition of SCAD with siRNA‐1186 significantly decreased SCAD expression, enzyme activity and ATP content, but obviously increased the content of free fatty acids. Meanwhile, SCAD siRNA treatment triggered the same apoptosis as cardiomyocytes treated with tBHP, such as the increase in cell apoptotic rate, the activation of caspase3 and the decrease in the Bcl‐2/Bax ratio, which showed that SCAD may play an important role in primary cardiomyocyte apoptosis. The changes of phosphonate AMP‐activated protein kinase α (p‐AMPKα) and Peroxisome proliferator‐activated receptor α (PPARα) in cardiomyocyte apoptosis were consistent with that of SCAD. Furthermore, PPARα activator fenofibrate and AMPKα activator AICAR treatment significantly increased the expression of SCAD and inhibited cardiomyocyte apoptosis. In conclusion, for the first time our findings directly demonstrated that SCAD may be as a new target to prevent cardiomyocyte apoptosis through the AMPK/PPARα/SCAD signal pathways.  相似文献   

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Conflicting results have been reported regarding whether the PPARgamma2 Pro12Ala polymorphism plays a role in the risk of type 2 diabetes (T2D), suggesting genetic heterogeneity. To investigate this issue, a meta-analysis of 41 published and 2 unpublished studies (a total of 42,910 subjects) was conducted. Ala12 carriers had a 19% T2D risk reduction, but this association was highly heterogeneous (p = 0.005). A great proportion (48%) of heterogeneity was explained by the controls' BMI, with risk reduction being greater when BMI was lower. Risk reduction of Ala12 carriers in Asia (35%) was higher than in Europe (15%, p = 0.02) and tended to be higher than in North America (18%, p = 0.10). Difference between Asians and Europeans was no longer significant (p = 0.15) after adjusting for the controls' BMI. Studies from Europe were still heterogeneous (p = 0.02) with risk reduction in Ala12 carriers being progressively smaller (test for trend in the odds ratios, p = 0.02) from Northern (26% reduction, p < 0.0001) to Central (10%, p = 0.04) and Southern (0%, p = 0.94) Europe. In conclusion, in our meta-analysis, the reduced risk of T2D in Ala12 carriers is not homogeneous. It is greater in Asia than in Europe and, among Europeans, it is higher in Northern Europe, barely significant in Central Europe, and nonexistent in Southern Europe.  相似文献   

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Rosiglitazone (RSG) has a variety of actions on both insulin sensitization and anti‐atherogenic effects. The molecular effect of RSG on monocyte/macrophage function in terms of de novo synthesis of adiponectin is not fully understood. Here, we examined the regulation of adiponectin expression in human monocytes/macrophages by RSG and its function on monocyte adhesion during initiation of atherosclerosis. Adiponectin expression in monocytes and macrophages was studied by RT‐PCR, quantitative real‐time PCR, Western blot, and immunocytochemistry. Signal transduction and adhesion molecules were studied in order to describe the function of de novo synthesized adiponectin in monocyte adhesion. Adiponectin was expressed and upregulated during monocyte differentiation. The expression of adiponectin was enhanced, albeit at a much lesser degree, by a peroxisome proliferator‐activated receptor gamma (PPARγ) agonist RSG, which was similar to what was found in adipocytes. Monocyte adhesion was remarkably reduced when the cells were treated with RSG for 12 h. This inhibitory effect of RSG was abolished by specific anti‐adiponectin antibodies but not by non‐immune immunoglobulin G in a serum‐free condition. Adiponectin‐induced suppression on monocyte adhesion was inhibited by a selective AMP‐activated protein kinase (AMPK) inhibitor compound C. The reduced expression and/or function of adhesion molecule integrins may underlie the mechanism contributing to reduced monocyte adhesion upon AMPK activation. Our data suggest that the inhibitory effect of RSG on monocyte adhesion might be at least in part through de novo adiponectin expression and activation of an AMPK‐dependent pathway, which might play an important role in atherogenesis. J. Cell. Biochem. 110: 1410–1419, 2010. © 2010 Wiley‐Liss, Inc.  相似文献   

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Accumulating evidence reveals that hormone leptin, mainly produced by adipocyte, plays a unique role in promotion of liver fibrosis. Hepatic stellate cell (HSC) activation is a key step in liver fibrosis and peroxisome‐proliferator activated receptor γ (PPARγ) exerts a crucial role in inhibition of HSC activation. Our previous researches demonstrated that leptin reduced PPARγ1 (a major subtype of PPARγ in HSCs) expression through GATA binding protein 2 (GATA2) binding to a site around ?2323 in PPARγ1 promoter. The present researches aimed to examine the effect of GATA3 on leptin‐induced inhibition of PPARγ1 and elucidate the relationship between GATA3 and GATA2. Gene expressions were analysed by real‐time PCR, western blot, luciferase assay and immunostaining. C57BL/6J ob/ob mouse model of thioacetamide‐induced liver injury was used in vivo. Results demonstrate that leptin significantly induces GATA3 expression in HSCs by multiple signalling pathways including NADPH oxidase pathway. There exist crosstalks between NADPH oxidase pathway and the other pathways. GATA3 can bind to GATA2‐binding site in PPARγ1 promoter and interacts with GATA2, contributing to leptin inhibition of PPARγ1 expression in HSCs. These data demonstrated novel molecular events for leptin inhibition of PPARγ1 expression in HSCs and thus might have potential implications for clarifying the detailed mechanisms underlying liver fibrosis in diseases in which circulating leptin levels are elevated such as non‐alcoholic steatohepatitis in obese patients.  相似文献   

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Obesity is directly associated with cancer, cardiovascular injury, hypertension, and type 2 diabetes. To date, Yamamoto identified that hot water extracts of edible Chrysanthemum (EC) induced cell size reduction, up‐regulation of adiponectin expression, and glucose absorption inhibition in 3T3‐L1 cells during adipocyte differentiation. Furthermore, EC showed antidiabetic effects such as improvement in insulin resistance and the down‐regulation of the blood glucose level and liver lipid content in type 2 diabetes model mice. In this study, we attempted to identify the antidiabetic components in EC. The methanol fraction from EC that showed relatively strong biological activity was purified by chromatography to obtain acacetin‐7‐O‐glucoside, apigenin‐7‐O‐glucoside, kaempferol‐7‐O‐glucoside, and naringenin‐7‐O‐glucoside. Among the isolated compounds and their aglycones, naringenin (NA) and naringenin‐7‐O‐glucoside (NAG) up‐regulated the intracellular accumulation of lipid and adiponectin‐secretion and down‐regulated the diameter of 3T3‐L1 cells during adipocyte differentiation. Because the PPARγ antagonist BADGE and PI3K/Akt inhibitors wortmannin and LY29004 inhibited the intracellular lipid accumulation by NA and NAG associated with adipogenesis, it was considered that NA and NAG showed the above‐mentioned activities via the activation of PPARγ as well as phosphorylation of the PI3K/Akt pathway.  相似文献   

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Human tau‐protein kinase I (TPK‐I; also known as glycogen synthase kinase‐3β, GSK‐3β) is a serine/threonine protein kinase. Full‐length TPK‐I/GSK‐3β was expressed in Escherichia coli as a fusion protein with a 6×His tag at the C‐terminus and was crystallized using the hanging‐drop vapour‐diffusion method. Prismatic crystals of ­dimensions 0.4 × 0.2 × 0.1 mm were obtained using 12–15%(w/v) polyethylene glycol 6000 as a precipitant at 278 K. The crystals belong to the orthorhombic space group P212121, with unit‐cell parameters a = 82.9, b = 86.1, c = 178.1 Å measured at 100 K, diffract to 2.3 Å resolution and seem to contain two enzyme molecules per asymmetric unit.  相似文献   

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