scholarly journals Empagliflozin Alleviates Hepatic Steatosis by Activating the AMPK-TET2-Autophagy Pathway in vivo and in vitro

2021 ◽  
Vol 11 ◽  
Author(s):  
Ting Li ◽  
Ting Fang ◽  
Linxin Xu ◽  
Xiangyang Liu ◽  
Xiaoyu Li ◽  
...  
Keyword(s):  
Hepatic Steatosis ◽  
Lipid Accumulation ◽  
Liver Steatosis ◽  
Fatty Degeneration ◽  
Hepatic Lipid Accumulation ◽  
Compound C ◽  
Hepatocyte Steatosis ◽  
Autophagy Pathway

Background: Metabolic associated fatty liver disease (MAFLD), characterized by hepatic lipid accumulation and fatty degeneration, is intertwined with obesity and type 2 diabetes mellitus (T2DM). Empagliflozin is a sodium-glucose cotransporter-2 inhibitor that effectively lowers blood glucose, but its effect on MAFLD and associated mechanisms are not fully understood.Methods: Eight-week-old db/db mice, an in vivo model, were administered empagliflozin or saline intragastrically. A hepatocyte steatosis model was established by inducing HL7702 cells with high glucose and palmitic acid and then treated with or without empagliflozin. The autophagy inhibitor (3-methyladenine, 3-MA) and AMP-activated protein kinase (AMPK) activator (AICAR)/inhibitor (Compound C) were used to determine the involvement of AMPK and autophagy in the regulation of lipid accumulation by empagliflozin. Ten-eleven translocation 2 (TET2) knockdown was achieved by siRNA transfection. Hepatic steatosis was evaluated by Oil Red O staining and triglyceride quantification. Immunohistochemistry, immunofluorescence, and western blot were performed to assess protein levels.Results: Empagliflozin alleviated liver steatosis in db/db mice and reduced triglyceride content and lipid accumulation in the hepatocyte steatosis model. Empagliflozin elevated autophagy, accompanied by an increase in p-AMPK and TET2. Both 3-MA and Compound C abolished the ability of empagliflozin to induce autophagy and reduce hepatic steatosis, while these effects could be recapitulated by AICAR treatment. TET2 knockdown resulted in autophagy inhibition and lipid accumulation despite empagliflozin treatment.Conclusion: Empagliflozin improves hepatic steatosis through the AMPK-TET2-autophagy pathway. The use of empagliflozin as a treatment for preventing and treating MAFLD in patients with T2DM warrants further study.

scholarly journals Liraglutide Alleviates Hepatic Steatosis by Activating the TFEB-Regulated Autophagy-Lysosomal Pathway

2020 ◽  
Vol 8 ◽  
Author(s):  
Yunyun Fang ◽  
Linlin Ji ◽  
Chaoyu Zhu ◽  
Yuanyuan Xiao ◽  
Jingjing Zhang ◽  
...  
Keyword(s):  
Hepatic Steatosis ◽  
Lipid Accumulation ◽  
Underlying Mechanism ◽  
Autophagic Flux ◽  
Alcoholic Fatty Liver ◽  
Lipid Degradation ◽  
Hepatic Lipid Accumulation ◽  
Lysosome Biogenesis

Liraglutide, a glucagon-like peptide-1 receptor agonist (GLP-1RA), has been demonstrated to alleviate non-alcoholic fatty liver disease (NAFLD). However, the underlying mechanism has not been fully elucidated. Increasing evidence suggests that autophagy is involved in the pathogenesis of hepatic steatosis. In this study, we examined whether liraglutide could alleviate hepatic steatosis through autophagy-dependent lipid degradation and investigated the underlying mechanisms. Herein, the effects of liraglutide on NAFLD were evaluated in a high-fat diet (HFD)-induced mouse model of NAFLD as well as in mouse primary and HepG2 hepatocytes exposed to palmitic acid (PA). The expression of the GLP-1 receptor (GLP-1R) was measured in vivo and in vitro. Oil red O staining was performed to detect lipid accumulation in hepatocytes. Electron microscopy was used to observe the morphology of autophagic vesicles and autolysosomes. Autophagic flux activity was measured by infecting HepG2 cells with mRFP-GFP-LC3 adenovirus. The roles of GLP-1R and transcription factor EB (TFEB) in autophagy-lysosomal activation were explored using small interfering RNA. Liraglutide treatment alleviated hepatic steatosis in vivo and in vitro. In models of hepatic steatosis, microtubule-associated protein 1B light chain-3-II (LC3-II) and SQSTM1/P62 levels were elevated in parallel to blockade of autophagic flux. Liraglutide treatment restored autophagic activity by improving lysosomal function. Furthermore, treatment with autophagy inhibitor chloroquine weakened liraglutide-induced autophagy activation and lipid degradation. TFEB has been identified as a key regulator of lysosome biogenesis and autophagy. The protein levels of nuclear TFEB and its downstream targets CTSB and LAMP1 were decreased in hepatocytes treated with PA, and these decreases were reversed by liraglutide treatment. Knockdown of TFEB expression compromised the effects of liraglutide on lysosome biogenesis and hepatic lipid accumulation. Mechanistically, GLP-1R expression was decreased in HFD mouse livers as well as PA-stimulated hepatocytes, and liraglutide treatment reversed the downregulation of GLP-1R expression in vivo and in vitro. Moreover, GLP-1R inhibition could mimic the effect of the TFEB downregulation-mediated decrease in lysosome biogenesis. Thus, our findings suggest that liraglutide attenuated hepatic steatosis via restoring autophagic flux, specifically the GLP-1R-TFEB-mediated autophagy-lysosomal pathway.

scholarly journals Dapagliflozin Alleviates Hepatic Steatosis by Restoring Autophagy via the AMPK-mTOR Pathway

2021 ◽  
Vol 12 ◽  
Author(s):  
Liuran Li ◽  
Qinghua Li ◽  
Wenbin Huang ◽  
Yibing Han ◽  
Huiting Tan ◽  
...  
Keyword(s):  
Hepatic Steatosis ◽  
Lipid Accumulation ◽  
Hepg2 Cells ◽  
Mtor Pathway ◽  
Hepatic Lipid ◽  
Hepatic Lipid Accumulation ◽  
Zdf Rats ◽  
Oxidation Enzyme

As a newly approved oral hypoglycaemic agent, the sodium-glucose cotransporter 2 (SGLT2) inhibitor dapagliflozin, which is derived from the natural product phlorizin can effectively reduce blood glucose. Recent clinical studies have found that dapagliflozin alleviates non-alcoholic fatty liver disease (NAFLD), but the specific mechanism remains to be explored. This study aimed to investigate the underlying mechanism of dapagliflozin in alleviating hepatocyte steatosis in vitro and in vivo. We fed the spontaneous type 2 diabetes mellitus rats with high-fat diets and cultured human normal liver LO2 cells and human hepatocellular carcinoma HepG2 cells with palmitic acid (PA) to induce hepatocellular steatosis. Dapagliflozin attenuated hepatic lipid accumulation both in vitro and in vivo. In Zucker diabetic fatty (ZDF) rats, dapagliflozin reduced hepatic lipid accumulation via promoting phosphorylation of acetyl-CoA carboxylase 1 (ACC1), and upregulating lipid β-oxidation enzyme acyl-CoA oxidase 1 (ACOX1). Furthermore, dapagliflozin increased the expression of the autophagy-related markers LC3B and Beclin1, in parallel with a drop in p62 level. Similar effects were observed in PA-stimulated LO2 cells and HepG2 cells. Dapagliflozin treatment could also significantly activated AMPK and reduced the phosphorylation of mTOR in ZDF rats and PA-stimulated LO2 cells and HepG2 cells. We demonstrated that dapagliflozin ameliorates hepatic steatosis by decreasing lipogenic enzyme, while inducing fatty acid oxidation enzyme and autophagy, which could be associated with AMPK activation. Moreover, our results indicate that dapagliflozin induces autophagy via the AMPK-mTOR pathway. These findings reveal a novel clinical application and functional mechanism of dapagliflozin in the treatment of NAFLD.

scholarly journals ERK-dependent mTOR pathway is involved in berberine-induced autophagy in hepatic steatosis

2016 ◽  
Vol 57 (4) ◽  
pp. 251-260 ◽  
Author(s):  
Qin He ◽  
Dan Mei ◽  
Sha Sha ◽  
Shanshan Fan ◽  
Lin Wang ◽  
...  
Keyword(s):  
Hepatic Steatosis ◽  
Lipid Accumulation ◽  
Mtor Pathway ◽  
Mice Model ◽  
Alcoholic Fatty Liver ◽  
Hepatic Lipid ◽  
Hepatic Lipid Accumulation ◽  
Positive Effects

Non-alcoholic fatty liver disease (NAFLD) is a burgeoning health problem and is considered as a hepatic manifestation of metabolic syndrome. Increasing evidence demonstrates that berberine (BBR), a natural plant alkaloid, is beneficial for obesity-associated NAFLD. However, the mechanisms about how BBR improves hepatic steatosis remain uncertain. Recently, some reports revealed that enhanced autophagy could decrease hepatic lipid accumulation. In this study, we first established a high-fed diet (HFD) mice model and oleate–palmitate-induced lipotoxicity hepatocytes to explore the association among BBR, autophagy and hepatic steatosis. Our data demonstrated that BBR had profound effects on improving hepatic lipid accumulation bothin vivoandin vitro, and led to high autophagy flux. The molecular alterations proceeding these changes were characterized by inhibition of the ERK/mTOR pathway. These findings suggest an important mechanism for the positive effects of BBR on hepatic steatosis, and may provide new evidence for the clinical use of BBR in NAFLD.

scholarly journals E3 ubiquitin ligase Grail promotes hepatic steatosis through Sirt1 inhibition

2021 ◽  
Vol 12 (4) ◽  
Author(s):  
Pei-Yao Liu ◽  
Cheng-Cheung Chen ◽  
Chia-Ying Chin ◽  
Te-Jung Liu ◽  
Wen-Chiuan Tsai ◽  
...  
Keyword(s):  
Hepatic Steatosis ◽  
Lipid Accumulation ◽  
Acid Synthesis ◽  
Sirtuin 1 ◽  
Nonalcoholic Fatty Liver ◽  
Expression Of Genes ◽  
Hepatic Fat ◽  
Underlying Mechanisms

AbstractIn obese adults, nonalcoholic fatty liver disease (NAFLD) is accompanied by multiple metabolic dysfunctions. Although upregulated hepatic fatty acid synthesis has been identified as a crucial mediator of NAFLD development, the underlying mechanisms are yet to be elucidated. In this study, we reported upregulated expression of gene related to anergy in lymphocytes (GRAIL) in the livers of humans and mice with hepatic steatosis. Grail ablation markedly alleviated the high-fat diet-induced hepatic fat accumulation and expression of genes related to the lipid metabolism, in vitro and in vivo. Conversely, overexpression of GRAIL exacerbated lipid accumulation and enhanced the expression of lipid metabolic genes in mice and liver cells. Our results demonstrated that Grail regulated the lipid accumulation in hepatic steatosis via interaction with sirtuin 1. Thus, Grail poses as a significant molecular regulator in the development of NAFLD.

scholarly journals Hepatic Lipid Accumulation Induced by a High-fat Diet Is Regulated by Nrf2 Through Multiple Pathways

2021 ◽  
Author(s):  
sheng Qiu ◽  
Zerong Liang ◽  
Qinan Wu ◽  
Miao Wang ◽  
Mengliu Yang ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Lipid Accumulation ◽  
High Fat Diet ◽  
Underlying Mechanism ◽  
Luciferase Assay ◽  
High Fat ◽  
Hepatic Lipid ◽  
Hepatic Lipid Accumulation

Abstract BackgroundNuclear factor erythroid 2-related factor 2 (Nrf2) is reportedly involved in hepatic lipid metabolism, but the results are contradictory and the underlying mechanism thus remains unclear. Herein we focused on elucidating the effects of Nrf2 on hepatic adipogenesis and on determining the possible underlying mechanism. We established a metabolic associated fatty liver disease (MAFLD) model in high fat diet (HFD) fed Nrf2 knockout (Nrf2 KO) mice; further, a cell model of lipid accumulation was established using mouse primary hepatocytes (MPHs) treated with free fatty acids (FAs). Using these models, we investigated the relationship between Nrf2 and autophagy and its role in the development of MAFLD.ResultsWe observed that Nrf2 expression levels were up-regulated in patients with MAFLD and diet-induced obese mice. Nrf2 deficiency led to hepatic lipid accumulation in vivo and in vitro, in addition to, promoting lipogenesis mainly by increasing SREBP-1 activity. Moreover, Nrf2 deficiency attenuated autophagic flux and inhibited the fusion of autophagosomes and lysosomes in vivo and in vitro. Weakened autophagy caused reduced lipolysis in the liver. Importantly, Chromatin immunoprecipitation-qPCR (ChIP-qPCR) and dual-luciferase assay results proved that Nrf2 bound to LAMP1 promoter and regulated its transcriptional activity. We accordingly report that Nrf2-LAMP1 interaction has an indispensable role in Nrf2-regulated hepatosteatosis. ConclusionsThese data collectively confirm that Nrf2 deficiency promotes hepatosteatosis by enhancing SREBP-1 activity and attenuating autophagy. To conclude, our data reveal a novel multi-pathway effect of Nrf2 on lipid metabolism in the liver, and we believe that multi-target intervention of Nrf2 signaling is a promising new strategy for the prevention and treatment of MAFLD.

scholarly journals The lncRNA Gm15622 stimulates SREBP-1c expression and hepatic lipid accumulation by sponging the miR-742-3p in mice

2020 ◽  
Vol 61 (7) ◽  
pp. 1052-1064 ◽  
Author(s):  
Minjuan Ma ◽  
Rui Duan ◽  
Lulu Shen ◽  
Mengting Liu ◽  
Yaya Ji ◽  
...  
Keyword(s):  
Lipid Accumulation ◽  
Lipid Deposition ◽  
In Vivo Models ◽  
Hepatic Lipid ◽  
Hepatic Lipid Accumulation ◽  
Regulatory Circuit ◽  
Murine Liver

Excessive lipid deposition is a hallmark of NAFLD. Although much has been learned about the enzymes and metabolites involved in NAFLD, few studies have focused on the role of long noncoding RNAs (lncRNAs) in hepatic lipid accumulation. Here, using in vitro and in vivo models of NAFLD, we found that the lncRNA Gm15622 is highly expressed in the liver of obese mice fed a HFD and in murine liver (AML-12) cells treated with free fatty acids. Investigating the molecular mechanism in the liver-enriched expression of Gm15622 and its effects on lipid accumulation in hepatocytes and on NAFLD pathogenesis, we found that Gm15622 acts as a sponge for the microRNA miR-742-3p. This sponging activity increased the expression of the transcriptional regulator SREBP-1c and promoted lipid accumulation in the liver of the HFD mice and AML-12 cells. Moreover, further results indicated that metformin suppresses Gm15622 and alleviates NAFLD-associated lipid deposition in mice. In conclusion, we have identified an lncRNA Gm15622/miR-742-3p/SREBP-1c regulatory circuit associated with NAFLD in mice, a finding that significantly advances our insight into how lipid metabolism and accumulation are altered in this metabolic disorder. Our results also suggest that Gm15622 may be a potential therapeutic target for managing NAFLD.

scholarly journals Metformin Ameliorates Ethanol-Induced Liver Triglyceride Accumulation by LKB1/AMPK/ACC Pathway

2021 ◽  
Author(s):  
Fotian Xie ◽  
Dongmei Wang ◽  
Kwok Fai So ◽  
Jia Xiao ◽  
Yi Lv
Keyword(s):  
Lipid Accumulation ◽  
Therapeutic Potential ◽  
Lipid Lowering ◽  
Liver Triglyceride ◽  
Hepatic Lipid Accumulation ◽  
Triglyceride Accumulation ◽  
Lipid Formation

Abstract Background: Hepatic lipid accumulation is one of the main pathological features of alcoholic liver disease. Metformin is an AMPK activator that has been shown to have lipid lowering effects. The purpose of this study was to investigate whether metformin had a beneficial effect on lipid accumulation in the pathogenesis of ALD.Methods: AML12 cells and male C57BL/6 mice were used to establish ALD models in vitro and in vivo, respectively. The effects of metformin on hepatocyte lipid accumulation and ALD progression in mice were detected. The role of LKB1/AMPK/ACC axis in metformin against ethanol-induced lipid accumulation was evaluated by siRNA and AAV-shRNA interference.Results: Metformin reduced the ethanol-induced lipid accumulation in AML12 cells through activating AMPK/ACC and SREBP1c and inhibiting PPARα. In addition, compared with control mice, metformin treatment inhibited ethanol-induced liver adipose accumulation and the increase of ALT and AST in serum. Interference with LKB1 attenuated the effect of metformin on ethanol-induced lipid accumulation both in vitro and in vivo.Conclusion: Metformin protects against lipid formation in ALD by activating LKB1/AMPK/ACC axis. Thus, metformin has therapeutic potential for the prevention of ALD.

scholarly journals Docosahexaenoic Acid Lessens Hepatic Lipid Accumulation and Inflammation via the AMP-Activated Protein Kinase and Endoplasmic Reticulum Stress Signaling Pathway in Grass Carp (Ctenopharyngodon Idella)

2021 ◽  
Author(s):  
Xiaocheng Huang ◽  
Jian Sun ◽  
Chenchen Bian ◽  
Shanghong Ji ◽  
Hong ji
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Kinase ◽  
Hepatic Steatosis ◽  
Grass Carp ◽  
Lipid Accumulation ◽  
Ctenopharyngodon Idella ◽  
Hepatic Inflammation ◽  
Amp Activated Protein Kinase

Abstract Background: The liver is the primary organ for frontline immune defense and lipid metabolism. Excessive lipid accumulation in the liver severely affects its metabolic homeostasis and causes metabolic diseases. Docosahexaenoic acid (DHA) is known for its beneficial effects on lipid metabolism and anti-inflammation, but its molecular mechanism remains unknown, especially in fish. In this study, we evaluated the protective effects of DHA on hepatic steatosis of grass carp (Ctenopharyngodon idella) in vivo and in vitro and mainly focused on lipogenesis and inflammation. Grass carp were fed with purified diets supplemented with 0%, 0.5% and 1% DHA for 8 weeks in vivo. Hepatocytes were treated with palmitic acid (PA) (200 μM) with or without DHA (50 or 100 μM) for 24 h in vitro. In addition, Compound C (CC, the inhibitor of AMP-activated protein kinase) was used to examine the mechanism of DHA on hepatic steatosis in vitro.Results: In this study, 1% DHA significantly decreased the liver triglyceride (TG), malondialdehyde (MDA), serum tumor necrosis factor α (TNFα) and nuclear factor kappa B (NFκB) contents. DHA (100 μM) effectively attenuated PA-induced lipid accumulation (P<0.05). Furthermore, DHA significantly inhibited endoplasmic reticulum (ER) stress and stimulated the expression of AMP-activated protein kinase (AMPK) and its downstream factors related to hepatic inflammation and lipogenesis in vivo and in vitro. However, the effects of DHA could be abrogated by CC in vitro.Conclusions: DHA exerted a protective effect on hepatic steatosis by inhibiting ER stress, improving antioxidant ability, relieving hepatic inflammation and inhibiting hepatic lipogenesis in an AMPK-dependent manner. Our findings give a theoretical foundation for further elucidation of the beneficial role of DHA in vertebrates.

scholarly journals Involvement of 5′-Activated Protein Kinase (AMPK) in the Effects of Resveratrol on Liver Steatosis

2018 ◽  
Vol 19 (11) ◽  
pp. 3473 ◽  
Author(s):  
Jenifer Trepiana ◽  
Iñaki Milton-Laskibar ◽  
Saioa Gómez-Zorita ◽  
Itziar Eseberri ◽  
Marcela González ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Hepatic Steatosis ◽  
Liver Steatosis ◽  
Therapeutic Tool ◽  
In Vivo Models ◽  
Chemical Products ◽  
Preventive Effects

This review focuses on the role of 5′-activated protein kinase (AMPK) in the effects of resveratrol (RSV) and some RSV derivatives on hepatic steatosis. In vitro studies, performed in different hepatic cell models, have demonstrated that RSV is effective in preventing liver TG accumulation by activating AMPK, due to its phosphorylation. These preventive effects have been confirmed in studies conducted in animal models, such as mice and rats, by administering the phenolic compound at the same time as the diet which induces TG accumulation in liver. The literature also includes studies focused on other type of models, such as animals showing alcohol-induced steatosis or even steatosis induced by administering chemical products. In addition to the preventive effects of RSV on hepatic steatosis, other studies have demonstrated that it can alleviate previously developed liver steatosis, thus its role as a therapeutic tool has been proposed. The implication of AMPK in the delipidating effects of RSV in in vivo models has also been demonstrated.

scholarly journals l-Carnitine counteracts in vitro fructose-induced hepatic steatosis through targeting oxidative stress markers

2019 ◽  
Vol 43 (4) ◽  
pp. 493-503 ◽  
Author(s):  
A. Montesano ◽  
P. Senesi ◽  
F. Vacante ◽  
G. Mollica ◽  
S. Benedini ◽  
...  
Keyword(s):  
Fatty Liver ◽  
Lipid Accumulation ◽  
Liver Diseases ◽  
Liver Steatosis ◽  
Ampk Activation ◽  
Nonalcoholic Fatty Liver ◽  
Oxidative Damages ◽  
Compound C ◽  
Human Hepatoma Hepg2 Cells

Abstract Purpose Nonalcoholic fatty liver disease (NAFLD) is defined by excessive lipid accumulation in the liver and involves an ample spectrum of liver diseases, ranging from simple uncomplicated steatosis to cirrhosis and hepatocellular carcinoma. Accumulating evidence demonstrates that high fructose intake enhances NAFLD development and progression promoting inhibition of mitochondrial β-oxidation of long-chain fatty acids and oxidative damages. l-Carnitine (LC), involved in β-oxidation, has been used to reduce obesity caused by high-fat diet, which is beneficial to ameliorating fatty liver diseases. Moreover, in the recent years, various studies have established LC anti-oxidative proprieties. The objective of this study was to elucidate primarily the underlying anti-oxidative mechanisms of LC in an in vitro model of fructose-induced liver steatosis. Methods Human hepatoma HepG2 cells were maintained in medium supplemented with LC (5 mM LC) with or without 5 mM fructose (F) for 48 h and 72 h. In control cells, LC or F was not added to medium. Fat deposition, anti-oxidative, and mitochondrial homeostasis were investigated. Results LC supplementation decreased the intracellular lipid deposition enhancing AMPK activation. However, compound C (AMPK inhibitor-10 μM), significantly abolished LC benefits in F condition. Moreover, LC, increasing PGC1 α expression, ameliorates mitochondrial damage-F induced. Above all, LC reduced ROS production and simultaneously increased protein content of antioxidant factors, SOD2 and Nrf2. Conclusion Our data seemed to show that LC attenuate fructose-mediated lipid accumulation through AMPK activation. Moreover, LC counteracts mitochondrial damages and reactive oxygen species production restoring antioxidant cellular machine. These findings provide new insights into LC role as an AMPK activator and anti-oxidative molecule in NAFLD.

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