scholarly journals Honokiol attenuates lipotoxicity in hepatocytes via activating SIRT3-AMPK mediated lipophagy

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Jingxin Liu ◽  
Tian Zhang ◽  
Jianzhong Zhu ◽  
Shuangchen Ruan ◽  
Rongsong Li ◽  
...  
Keyword(s):  
Lipid Accumulation ◽  
Energy Homeostasis ◽  
Liver Steatosis ◽  
Nile Red ◽  
Acid Mixture ◽  
Amino Acid Residues ◽  
Alcoholic Fatty Liver ◽  
Compound C ◽  
Chain Acyl ◽  
Intracellular Lipid Accumulation

Abstract Background Non-alcoholic fatty liver disease (NAFLD) is characterized by ectopic accumulation of triglycerides in the liver. Emerging evidence has demonstrated that lipophagy regulates lipid mobilization and energy homeostasis in the liver. Sirtuin 3 (SIRT3), a mitochondrial NAD+-dependent deacetylase, modulates the activities of several substrates involving in autophagy and energy metabolism. Honokiol (HK) is a natural lignan from the plants of Magnolia genus that exhibits potent liver protective property. Methods AML12 was challenged with 500 μM palmitic acid and 250 μM oleic acid mixture solution to induce lipotoxicity. C57BL/6J mice were fed with a choline-deficient high fat diet (CDHFD) to generate liver steatosis. The expression of autophagy-related and AMP-activated protein kinase (AMPK) pathway proteins was evaluated by Western blotting and immunofluorescence staining. Intracellular lipid accumulation was validated by Nile red staining. Molecular docking analysis was performed on AutoDock 4.2. Results HK (5 and 10 μM) was found to attenuate lipid accumulation through promoting SIRT3-AMPK-mediated autophagy, mainly on lipid droplets. HK had hydrophobic interaction with amino acid residues (PHE294, GLU323 and VAL324) and NAD+. Moreover, HK improved mitochondrial function to enhance lipolysis, through decreasing the acetylated long-chain acyl-CoA dehydrogenase level. In CDHFD-fed mice, HK (2.5 and 10 mg/Kg) treatment obviously prevented lipid accumulation in the liver. And co-treatment of the AMPK inhibitor, Compound C, almost abolished the above changes. Conclusions These results suggest that HK could ameliorate lipotoxicity in hepatocytes by activating SIRT3-AMPK-lipophagy axis, which might be a potential therapeutic agent against NAFLD.

scholarly journals Honokiol Attenuates Lipotoxicity in Hepatocytes via Activating SIRT3-AMPK Mediated Lipophagy

2021 ◽  
Author(s):  
Zhang Tian ◽  
Jingxin Liu ◽  
Jianzhong Zhu ◽  
Rongsong Li ◽  
Ligen Lin
Keyword(s):  
Lipid Accumulation ◽  
Energy Homeostasis ◽  
Nile Red ◽  
Acid Mixture ◽  
Amino Acid Residues ◽  
Alcoholic Fatty Liver ◽  
Docking Analysis ◽  
Chain Acyl ◽  
Intracellular Lipid Accumulation ◽  
Amp Activated Protein Kinase

Abstract Background: Non-alcoholic fatty liver disease (NAFLD) is characterized by ectopic accumulation of triglycerides in the liver. Emerging evidence has demonstrated that lipophagy regulates lipid mobilization and energy homeostasis in liver. Sirtuin 3 (SIRT3), a mitochondrial NAD+-dependent deacetylase, modulates the activities of several substrates involving in autophagy and energy metabolism. Honokiol (HK) is a natural lignan from the plants of Magnolia genus that exhibits potent liver protective property. Methods: AML12 was challenged with 500 μM palmitic acid and 250 μM oleic acid mixture solution to induce lipotoxicity. The expression of autophagy-related and AMP-activated protein kinase (AMPK) pathway proteins was evaluated by Western blotting and immunofluorescence staining. Intracellular lipid accumulation was validated by Nile red staining. Molecular docking analysis was performed on AutoDock 4.2.Results: HK (5 and 10 μM) was found to attenuate lipid accumulation through promoting SIRT3-AMPK-mediated autophagy, mainly on lipid droplets. HK had hydrophobic interaction with amino acid residues (PHE294, GLU323 and VAL324) and NAD+. Moreover, HK improved mitochondrial function to enhance lipolysis, through decreasing the acetylated long-chain acyl-CoA dehydrogenase level. Conclusions: These results suggest that HK could ameliorate lipotoxicity in hepatocytes by activating SIRT3-AMPK-lipophagy axis, which might be a potential therapeutic agent against NAFLD.

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 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.

Acute Elevated Resistin Exacerbates Mitochondrial Damage and Aggravates Liver Steatosis Through AMPK/PGC-1α Signaling Pathway in Male NAFLD Mice

2020 ◽  
Author(s):  
Fengyun Wen ◽  
Zhuoyan Shi ◽  
Xiaoping Liu ◽  
Yuguang Tan ◽  
Lan Wei ◽  
...  
Keyword(s):  
Lipid Accumulation ◽  
Hepg2 Cells ◽  
Liver Lipid ◽  
Liver Steatosis ◽  
Mitochondrial Morphology ◽  
Mitochondrial Content ◽  
Alcoholic Fatty Liver ◽  
Related Development ◽  
Liver Lipid Metabolism

AbstractResistin was identified as a link between obesity and insulin resistance and is associated with many diseases in mice. Deciphering the related development and molecular mechanism is necessary for the treatment of these diseases. Previous studies have revealed that increased resistin levels are correlated with lipid accumulation and play a role in non-alcoholic fatty liver disease (NAFLD) development. However, the exact mechanisms underlying these processes remain unclear. To further clarify whether acute elevated resistin level exacerbated liver steatosis, a high-fat diet-induced NAFLD animal model was used and treated with or without resistin for 6 days. We discovered that resistin altered mitochondrial morphology, decreased mitochondrial content, and increased lipid accumulation in HFD mice. qRT-PCR and western blot analysis showed that acute elevated resistin significantly altered the gene expression of mitochondrial biogenesis and liver lipid metabolism molecules in HFD mice. Consequently, in vitro experiments verified that resistin reduced the mitochondrial content, impaired the mitochondrial function and increased the lipid accumulation of palmitate-treated HepG2 cells. Additionally, we demonstrated that resistin upregulated proinflammatory factors, which confirmed that resistin promoted the development of inflammation in NAFLD mice and palmitate-treated HepG2 cells. Signaling-transduction analysis demonstrated that acute elevated resistin aggravated liver steatosis through AMPK/PGC-1α pathway in male mice. This reveals a novel pathway through which lipogenesis is induced by resistin and suggests that maintaining mitochondrial homeostasis may be key to treatments for preventing resistin-induced NAFLD aggravation.

scholarly journals Naringenin Attenuates Non-Alcoholic Fatty Liver Disease by Enhancing Energy Expenditure and Regulating Autophagy via AMPK

2021 ◽  
Vol 12 ◽  
Author(s):  
Ying Yang ◽  
Yue Wu ◽  
Jie Zou ◽  
Yu-Hao Wang ◽  
Meng-Xia Xu ◽  
...  
Keyword(s):  
Western Blotting ◽  
Lipid Accumulation ◽  
C2c12 Myotubes ◽  
Autophagic Flux ◽  
Atp Content ◽  
Alcoholic Fatty Liver ◽  
Compound C ◽  
Oil Red O Staining ◽  
Alcoholic Fatty Liver Disease ◽  
Oil Red O

Background: The prevalence of non-alcoholic fatty liver disease (NAFLD) keeps growing recently.Purpose: To investigate the effects and mechanisms of naringenin (NAR) on NAFLD.Methods: High-fat diet (HFD)-induced NAFLD rats were orally administered with NAR at 10, 30, and 90 mg/kg for 2 weeks. The serum level of triglyceride (TG), total cholesterol (TC), glutamic-oxaloacetic transaminase (AST), and glutamic-pyruvic transaminase (ALT) was measured. The hepatic histology was detected by H&E and oil red O staining. L02 and Huh-7 cells were induced by sodium oleate to establish a NAFLD cell model. The effects of NAR on lipid accumulation were detected by oil red O staining. The glucose uptake and ATP content of 3T3-L1 adipocytes and C2C12 myotubes were measured. The expression of proteins of the AMPK signaling pathway in 3T3-L1 adipocytes and C2C12 myotubes was assessed by Western blotting. The mitochondrial biogenesis of 3T3-L1 adipocytes and C2C12 myotubes was measured by mitotracker orange staining and Western blotting. The biomarkers of autophagy were detected by Western blotting and immunofluorescence. The binding of NAR to AMPKγ1 was analyzed by molecular docking. Chloroquine and compound C were employed to block autophagic flux and AMPK, respectively.Results: NAR alleviated HFD-induced NAFLD in rats at 10, 30, and 90 mg/kg. NAR attenuated lipid accumulation in L02 and Huh-7 cells at 0.7, 2.2, 6.7, and 20 μM. NAR increased glucose uptake, decreased the ATP content, activated the CaMKKβ/AMPK/ACC pathway, and enhanced the mitochondrial biogenesis in 3T3-L1 adipocytes and C2C12 myotubes. NAR increased autophagy and promoted the initiation of autophagic flux in 3T3-L1 preadipocytes and C2C12 myoblasts, while it inhibited autophagy in NAFLD rats, 3T3-L1 adipocytes, and C2C12 myotubes. Molecular docking showed that NAR binds to AMPKγ1. Compound C blocked effects of NAR on lipid accumulation and autophagy in L02 cells.Conclusion: NAR alleviates NAFLD by increasing energy expenditure and regulating autophagy via activating AMPK directly and indirectly. The direct binding of NAR and AMPKγ1 needs further validation.

scholarly journals Dissecting lipid accumulation of microalgae Nannochloropsis oculata using fluorescent image analysis

2019 ◽  
Vol 2 (5) ◽  
pp. 5-11
Author(s):  
Tu Cam Trinh ◽  
Huong Thanh Tran ◽  
Viet Trang Bui
Keyword(s):  
Cell Suspension ◽  
Cell Density ◽  
Lipid Accumulation ◽  
Lipid Droplets ◽  
Nile Red ◽  
Nannochloropsis Oculata ◽  
Cell Diameter ◽  
Intracellular Lipid ◽  
Processing Program ◽  
Intracellular Lipid Accumulation

Cell suspension of Nannochloropsis oculata was cultured in a modified f/2 medium to study the changes of lipid content during phases of growth. The growth of cell suspension was determined by measuring the cell density and diameter under light microscope. To observe and evaluate the accumulation of lipid droplets in microalgae cells, lipid droplets were stained with Nile Red fluorescent dye then examined under fluorescence microscope and the obtained images were analyzed using Fiji ImageJ, an image processing program. The cell density increased quickly at the first 6 days of culture while cell diameter reached the highest value at the 8th day and 20th day of culture. The presence of lipid droplets in the cells could be observed from the 20th day of culture. The size of lipid droplets was gradually increased after 60 days. Treatment of depleted nitrogen for 4 days resulted an increase in the accumulation of lipid. The intracellular lipid accumulation during phases of growth of the cell suspension under nitrogen-depleted conditions was also discussed.

scholarly journals Posidonia oceanica (L.) Delile Extract Reduces Lipid Accumulation through Autophagy Activation in HepG2 Cells

2021 ◽  
Vol 14 (10) ◽  
pp. 969
Author(s):  
Marzia Vasarri ◽  
Emanuela Barletta ◽  
Donatella Degl’Innocenti
Keyword(s):  
Lipid Accumulation ◽  
Hepg2 Cells ◽  
Posidonia Oceanica ◽  
Intracellular Lipid ◽  
Alcoholic Fatty Liver ◽  
Ribosomal Protein S6 ◽  
Intracellular Lipid Accumulation ◽  
Human Hepatoma Hepg2 Cells ◽  
Lipid Reduction ◽  
The Relationship

Posidonia oceanica (L.) Delile is a marine plant traditionally used as an herbal medicine for various health disorders. P. oceanica leaf extract (POE) has been shown to be a phytocomplex with cell-safe bioactivities, including the ability to trigger autophagy. Autophagy is a key pathway to counteract non-alcoholic fatty liver disease (NAFLD) by controlling the breakdown of lipid droplets in the liver. The aim of this study was to explore the ability of POE to trigger autophagy and reduce lipid accumulation in human hepatoma (HepG2) cells and then verify the possible link between the effect of POE on lipid reduction and autophagy activation. Expression levels of autophagy markers were monitored by the Western blot technique in POE-treated HepG2 cells, whereas the extent of lipid accumulation in HepG2 cells was assessed by Oil red O staining. Chloroquine (CQ), an autophagy inhibitor, was used to study the relationship between POE-induced autophagy and intracellular lipid accumulation. POE was found to stimulate an autophagy flux over time in HepG2 cells by lowering the phosphorylation state of ribosomal protein S6, increasing Beclin-1 and LC3-II levels, and decreasing p62 levels. By blocking autophagy with CQ, the effect of POE on intracellular lipid accumulation was clearly reversed, suggesting that the POE phytocomplex may reduce lipid accumulation in HepG2 cells by activating the autophagic process. This work indicates that P. oceanica may be considered as a promising molecule supplier to discover new natural approaches for the management of NAFLD.

Resveratrol ameliorates lipid accumulation in HepG2 cells, associated with down-regulation of lipin1 expression

2016 ◽  
Vol 94 (2) ◽  
pp. 185-189 ◽  
Author(s):  
Li Ying Tang ◽  
Yi Chen ◽  
Bei Bei Rui ◽  
Cheng Mu Hu
Keyword(s):  
Oleic Acid ◽  
Lipid Accumulation ◽  
Hepg2 Cells ◽  
Regulatory Element ◽  
Control Group ◽  
Down Regulation ◽  
Alcoholic Fatty Liver ◽  
Compound C ◽  
Element Binding Protein ◽  
Amp Activated Protein Kinase

The pathogenesis of alcoholic fatty liver (AFL) disease is associated with the excessive accumulation of lipids in hepatocytes as well as oxidative stress. Resveratrol (RES), a dietary polyphenol found in red wine and grapes, has been shown to protect against AFL disease. However, the precise mechanisms that lead to this protective effect remain elusive. In this study, we used HepG2 cells to investigate the effects of RES on lipid metabolism and the mechanisms underlying these effects. HepG2 cells were cultured with oleic acid and alcohol for 48 h to induce excessive lipid accumulation. Oil red O staining showed that administration of oleic acid and alcohol induced more lipid accumulation than was observed in the control group, and that RES (15, 45, or 135 μmol/L) treatment reduced intracellular lipid droplets. RES treatment also significantly attenuated hepatic steatosis and lowered levels of intracellular triglycerides (TG). Western blot analysis showed that RES enhanced the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) and down-regulated the expression of sterol regulatory element-binding protein 1c (SREBP-1c) and lipin1. However, compound C, an AMPK inhibitor, reversed these effects of RES. In conclusion, RES reduced lipid accumulation and protected HepG2 cells. This effect may be associated with the down-regulation of SREBP-1c and lipin1 expression, increased levels of phosphorylated AMPK and ACC, and the activation of AMPK–lipin1 signaling.

Therapeutic Effect of Metformin and Vitamin E Versus Prescriptive Diet in Obese Adolescents with Fatty Liver

2011 ◽  
Vol 81 (6) ◽  
pp. 398-406 ◽  
Author(s):  
Akcam ◽  
Boyaci ◽  
Pirgon ◽  
Kaya ◽  
Uysal ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Vitamin E ◽  
Fatty Liver ◽  
Liver Steatosis ◽  
Tnf Alpha ◽  
Dietary Advice ◽  
Model Assessment ◽  
Fasting Insulin ◽  
Alcoholic Fatty Liver ◽  
Obese Adolescents

Objective: The aim of the study was to determine whether metformin or vitamin E treatment for six months is effective in reducing body weight, blood pressure, and also ameliorating insulin resistance, adiponectin, and tumor necrosis factor (TNF)-alpha in obese adolescents with non-alcoholic fatty liver disease (NAFLD). Methods: Sixty-seven obese adolescents with liver steatosis (age range, 9 - 17 years) were included in the study. The metformin group received an 850-mg dose of metformin daily and the vitamin E group received 400 U vitamin E /daily, in capsule form for 6 months, plus an individually tailored diet, exercise, and behavioral therapy. Results: After 6 months later, there was a significant decline in body mass index, and fasting insulin and homeostatic model assessment (HOMA) values in all three groups. Moreover, in comparingson of changes in HOMA among the groups, the metformin- treated group showed significantly improved metabolic control and insulin sensitivity (HOMA) at the end of the study. There were no significant differences for changes of adiponectin, TNF-alpha, in all three groups after 6 months study. Conclusion: These data suggest that metformin treatment is more effective than dietary advice and vitamin E treatment in reducing insulin resistance, and also in ameliorating metabolic parameters such as fasting insulin and lipid levels, in obese adolescents having NAFLD.

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