scholarly journals A High-Fat Diet Attenuates Amp-Activated Protein Kinase α1 in Adipocytes to Induce Exosome Shedding and Nonalcoholic Fatty Liver Development in Vivo

Diabetes ◽  
2020 ◽  
pp. db200146
Author(s):  
Chenghui Yan ◽  
Xiaoxiang Tian ◽  
Jiayin Li ◽  
Dan Liu ◽  
Ding Ye ◽  
...  
2020 ◽  
Author(s):  
Ada Admin ◽  
Chenghui Yan ◽  
Xiaoxiang Tian ◽  
Jiayin Li ◽  
Dan Liu ◽  
...  

Exosomes are important for intercellular communication, but the role of exosomes in the communication between adipose tissue (<a>AT</a>) and the liver remains unknown. The aim of this study is to determine the contribution of AT-derived exosomes in nonalcoholic fatty liver disease (<a>NAFLD</a>). Exosome components, liver fat content, and liver function were monitored in AT in mice fed a <a>high-fat diet </a>(<a>HFD</a>) or treated with metformin- or GW4869 and with AMP-activated protein kinase (AMPKα1)<i> </i>floxed<i> (Prkaα1</i><sup>fl/fl</sup>/WT), <a><i>Prkaα1</i><sup>-/-</sup></a>, liver tissue-specific <i>Prkaα1</i><sup>-/-</sup>, or AT-specific <i>Prkaα1</i><sup>-/-</sup> modification. In cultured adipocytes and white adipose tissue (WAT), the absence of <a><i>AMPKα1</i></a> increased exosome release and exosomal proteins by elevating <a>tumor susceptibility gene 101 (<i>TSG101</i></a>)-mediated exosome biogenesis. In adipocytes treated with palmitic acid, TSG101 facilitated scavenger receptor class B (CD36) sorting into exosomes. CD36-containing exosomes were then endocytosed by hepatocytes to induce lipid accumulation and inflammation. Consistently, an HFD induced more severe lipid accumulation and cell death in <a><i>Prkaα1</i><sup>-/-</sup> </a>and adipose tissue-specific <i>Prkaα1</i><sup>-/-</sup> mice than in WT and liver-specific <i>Prkaα1</i><sup>-/-</sup> mice. AMPK activation by metformin reduced adipocyte-mediated exosome release and mitigated fatty liver development in WT and liver specific <i>Prkaα1</i><sup>-/-</sup> mice. Moreover, administration of the exosome inhibitor GW4869 blocked exosome secretion and alleviated HFD-induced fatty livers in <i>Prkaα1</i><sup>-/-</sup> and adipocyte-specific <i>Prkaα1</i><sup>-/-</sup> mice. We conclude that HFD-mediated AMPKα1 inhibition promotes NAFLD by increasing numbers of AT C<a>D36</a>-containing exosomes.


2020 ◽  
Author(s):  
Ada Admin ◽  
Chenghui Yan ◽  
Xiaoxiang Tian ◽  
Jiayin Li ◽  
Dan Liu ◽  
...  

Exosomes are important for intercellular communication, but the role of exosomes in the communication between adipose tissue (<a>AT</a>) and the liver remains unknown. The aim of this study is to determine the contribution of AT-derived exosomes in nonalcoholic fatty liver disease (<a>NAFLD</a>). Exosome components, liver fat content, and liver function were monitored in AT in mice fed a <a>high-fat diet </a>(<a>HFD</a>) or treated with metformin- or GW4869 and with AMP-activated protein kinase (AMPKα1)<i> </i>floxed<i> (Prkaα1</i><sup>fl/fl</sup>/WT), <a><i>Prkaα1</i><sup>-/-</sup></a>, liver tissue-specific <i>Prkaα1</i><sup>-/-</sup>, or AT-specific <i>Prkaα1</i><sup>-/-</sup> modification. In cultured adipocytes and white adipose tissue (WAT), the absence of <a><i>AMPKα1</i></a> increased exosome release and exosomal proteins by elevating <a>tumor susceptibility gene 101 (<i>TSG101</i></a>)-mediated exosome biogenesis. In adipocytes treated with palmitic acid, TSG101 facilitated scavenger receptor class B (CD36) sorting into exosomes. CD36-containing exosomes were then endocytosed by hepatocytes to induce lipid accumulation and inflammation. Consistently, an HFD induced more severe lipid accumulation and cell death in <a><i>Prkaα1</i><sup>-/-</sup> </a>and adipose tissue-specific <i>Prkaα1</i><sup>-/-</sup> mice than in WT and liver-specific <i>Prkaα1</i><sup>-/-</sup> mice. AMPK activation by metformin reduced adipocyte-mediated exosome release and mitigated fatty liver development in WT and liver specific <i>Prkaα1</i><sup>-/-</sup> mice. Moreover, administration of the exosome inhibitor GW4869 blocked exosome secretion and alleviated HFD-induced fatty livers in <i>Prkaα1</i><sup>-/-</sup> and adipocyte-specific <i>Prkaα1</i><sup>-/-</sup> mice. We conclude that HFD-mediated AMPKα1 inhibition promotes NAFLD by increasing numbers of AT C<a>D36</a>-containing exosomes.


2016 ◽  
Vol 44 (03) ◽  
pp. 551-564 ◽  
Author(s):  
Mingxing Yang ◽  
Xiumin Li ◽  
Xin Zeng ◽  
Zhimin Ou ◽  
Mei Xue ◽  
...  

Nonalcoholic fatty liver disease (NAFLD) is a common metabolic disorder characterized by the accumulation of excess fat in the liver. Rheum palmatumL. (RP) decoctions have been reported to ameliorate NAFLD. The aim of the present study was to investigate the effects and underlying mechanisms of RP in fatty liver disease induced by a high-fat diet (HFD) in rats. Low and high doses of aqueous RP extraction were orally administered to HFD-fed rats for six weeks. Body weight, tissue weight, glucose tolerance, insulin tolerance, hepatic morphology, and liver triglyceride (TG) content were assessed. The effects of RP on the expressions of lipogenic and lipolysis genes were measured by quantitative real-time PCR. The phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) was determined by Western blotting. Treatment with low-dose RP significantly reduced liver weight, liver TG content, and improved glucose tolerance in HFD-fed rats. Consistently, RP attenuated excess fat accumulation and downregulated the expression of lipogenic genes in the liver. Further, an increased phosphorylation of AMPK and ACC was observed. These findings suggest that low-dose RP alleviates hepatosteatosis, at least in part, by stimulating AMPK activity.


2018 ◽  
Vol 9 (4) ◽  
pp. 2043-2050 ◽  
Author(s):  
Fenglin Zhang ◽  
Wei Ai ◽  
Xiaoquan Hu ◽  
Yingying Meng ◽  
Cong Yuan ◽  
...  

In vivo and in vitro studies show that phytol stimulates the browning of mice iWAT and formation of brown-like adipocytes in the differentiated 3T3-L1 through the activation of the AMPKα signaling pathway.


2017 ◽  
Vol 117 (5) ◽  
pp. 645-661 ◽  
Author(s):  
Jyoti Gautam ◽  
Vikram Khedgikar ◽  
Priyanka Kushwaha ◽  
Dharmendra Choudhary ◽  
Geet Kumar Nagar ◽  
...  

AbstractBalance between adipocyte and osteoblast differentiation is the key link of disease progression in obesity and osteoporosis. We have previously reported that formononetin (FNT), an isoflavone extracted from Butea monosperma, stimulates osteoblast formation and protects against postmenopausal bone loss. The inverse relationship between osteoblasts and adipocytes prompted us to analyse the effect of FNT on adipogenesis and in vivo bone loss, triggered by high-fat diet (HFD)-induced obesity. The anti-obesity effect and mechanism of action of FNT was determined in 3T3-L1 cells and HFD-induced obese male mice. Our findings show that FNT suppresses the adipogenic differentiation of 3T3-L1 fibroblasts, through down-regulation of key adipogenic markers such as PPARγ, CCAAT/enhancer-binding protein alpha (C/EBPα) and sterol regulatory element-binding protein (SREBP) and inhibits intracellular TAG accumulation. Increased intracellular reactive oxygen species levels and AMP-activated protein kinase (AMPK) activation accompanied by stabilisation of β-catenin were attributed to the anti-adipogenic action of FNT. In vivo, 12 weeks of FNT treatment inhibited the development of obesity in mice by attenuating HFD-induced body weight gain and visceral fat accumulation. The anti-obesity effect of FNT results from increased energy expenditure. FNT also protects against HFD-induced dyslipidaemia and rescues deterioration of trabecular bone volume by increasing bone formation and decreasing bone resorbtion caused by HFD. FNT’s rescuing action against obesity-induced osteoporosis commenced at the level of progenitors, as bone marrow progenitor cells, obtained from the HFD mice group supplemented with FNT, showed increased osteogenic and decreased adipogenic potentials. Our findings suggest that FNT inhibits adipogenesis through AMPK/β-catenin signal transduction pathways and protects against HFD-induced obesity and bone loss.


2014 ◽  
Vol 37 (9) ◽  
pp. 1169-1176 ◽  
Author(s):  
You-Jin Choi ◽  
Hyo-Ryung Suh ◽  
Yujin Yoon ◽  
Kyung-Jin Lee ◽  
Dong Gwang Kim ◽  
...  

2015 ◽  
Vol 35 (6) ◽  
pp. 2349-2359 ◽  
Author(s):  
Youli Xi ◽  
Miaozong Wu ◽  
Hongxia Li ◽  
Siqi Dong ◽  
Erfei Luo ◽  
...  

Background/Aims: Obesity-associated fatty liver disease affects millions of individuals. This study aimed to evaluate the therapeutic effects of baicalin to treat obesity and fatty liver in high fat diet-induced obese mice, and to study the potential molecular mechanisms. Methods: High fat diet-induced obese animals were treated with different doses of baicalin (100, 200 and 400 mg/kg/d). Whole body, fat pad and liver were weighed. Hyperlipidemia, liver steatosis, liver function, and hepatic Ca2+/CaM-dependent protein kinase kinase β (CaMKKβ) / AMP-activated protein kinase (AMPK) / acetyl-CoA carboxylase (ACC) were further evaluated. Results: Baicalin significantly decreased liver, epididymal fat and body weights in high fat diet-fed mice, which were associated with decreased serum levels of triglycerides, total cholesterol, LDL, alanine transaminase and aspartate transaminase, but increased serum HDL level. Pathological analysis revealed baicalin dose-dependently decreased the degree of hepatic steatosis, with predominantly diminished macrovesicular steatosis at lower dose but both macrovesicular and microvesicular steatoses at higher dose of baicalin. Baicalin dose-dependently inhibited hepatic CaMKKβ/AMPK/ACC pathway. Conclusion: These data suggest that baicalin up to 400 mg/kg/d is safe and able to decrease the degree of obesity and fatty liver diseases. Hepatic CaMKKβ/AMPK/ACC pathway may mediate the therapeutic effects of baicalin in high fat diet animal model.


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