scholarly journals Sterol O-acyltransferase 2 chaperoned by apolipoprotein J facilitates hepatic lipid accumulation following viral and nutrient stresses

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Hung-Yu Sun ◽  
Tzu-Ying Chen ◽  
Yu-Ching Tan ◽  
Chun-Hsiang Wang ◽  
Kung-Chia Young
Keyword(s):  
Cholesteryl Ester ◽  
Lipid Accumulation ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Alcoholic Fatty Liver ◽  
Hepatic Lipid ◽  
Hepatic Lipid Accumulation ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Regions ◽  
Apolipoprotein J

AbstractThe risks of non-alcoholic fatty liver disease (NAFLD) include obese and non-obese stresses such as chronic hepatitis C virus (HCV) infection, but the regulatory determinants remain obscure. Apolipoprotein J (ApoJ) served as an ER-Golgi contact-site chaperone near lipid droplet (LD), facilitating HCV virion production. We hypothesized an interplay between hepatic ApoJ, cholesterol esterification and lipid deposit in response to NAFLD inducers. Exposures of HCV or free-fatty acids exhibited excess LDs along with increased ApoJ expression, whereas ApoJ silencing alleviated hepatic lipid accumulation. Both stresses could concomitantly disperse Golgi, induce closer ApoJ and sterol O-acyltransferase 2 (SOAT2) contacts via the N-terminal intrinsically disordered regions, and increase cholesteryl-ester. Furthermore, serum ApoJ correlated positively with cholesterol and low-density lipoprotein levels in normal glycaemic HCV patients, NAFLD patients and in mice with steatosis. Taken together, hepatic ApoJ might activate SOAT2 to supply cholesteryl-ester for lipid loads, thus providing a therapeutic target of stress-induced steatosis.

scholarly journals Inhibition of Extracellular Cathepsin D Reduces Hepatic Lipid Accumulation and Leads to Mild Changes in Inflammationin NASH Mice

2021 ◽  
Vol 12 ◽  
Author(s):  
Tulasi Yadati ◽  
Tom Houben ◽  
Albert Bitorina ◽  
Yvonne Oligschlaeger ◽  
Marion J. Gijbels ◽  
...  
Keyword(s):  
Lipid Accumulation ◽  
Cathepsin D ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Label Free ◽  
Sprague Dawley ◽  
Knock Out ◽  
Hepatic Lipid ◽  
Metabolic Inflammation ◽  
Hepatic Lipid Accumulation

Background & AimsThe lysosomal enzyme, cathepsin D (CTSD) has been implicated in the pathogenesis of non-alcoholic steatohepatitis (NASH), a disease characterised by hepatic steatosis and inflammation. We have previously demonstrated that specific inhibition of the extracellular CTSD leads to improved metabolic features in Sprague-Dawley rats with steatosis. However, the individual roles of extracellular and intracellular CTSD in NASH are not yet known. In the current study, we evaluated the underlying mechanisms of extracellular and intracellular CTSD fractions in NASH-related metabolic inflammation using specific small-molecule inhibitors.MethodsLow-density lipoprotein receptor knock out (Ldlr-/-) mice were fed a high-fat, high cholesterol (HFC) diet for ten weeks to induce NASH. Further, to investigate the effects of CTSD inhibition, mice were injected either with an intracellular (GA-12) or extracellular (CTD-002) CTSD inhibitor or vehicle control at doses of 50 mg/kg body weight subcutaneously once in two days for ten weeks.ResultsLdlr-/- mice treated with extracellular CTSD inhibitor showed reduced hepatic lipid accumulation and an associated increase in faecal bile acid levels as compared to intracellular CTSD inhibitor-treated mice. Furthermore, in contrast to intracellular CTSD inhibition, extracellular CTSD inhibition switched the systemic immune status of the mice to an anti-inflammatory profile. In line, label-free mass spectrometry-based proteomics revealed that extra- and intracellular CTSD fractions modulate proteins belonging to distinct metabolic pathways.ConclusionWe have provided clinically translatable evidence that extracellular CTSD inhibition shows some beneficial metabolic and systemic inflammatory effects which are distinct from intracellular CTSD inhibition. Considering that intracellular CTSD inhibition is involved in essential physiological processes, specific inhibitors capable of blocking extracellular CTSD activity, can be promising and safe NASH drugs.

Dietary raffinose ameliorates hepatic lipid accumulation induced by cholic acid via modulation of enterohepatic bile acid circulation in rats

2021 ◽  
pp. 1-26
Author(s):  
Kenta Maegawa ◽  
Haruka Koyama ◽  
Satoru Fukiya ◽  
Atsushi Yokota ◽  
Koichiro Ueda ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Bile Acid ◽  
Cholic Acid ◽  
Lipid Accumulation ◽  
Enterohepatic Circulation ◽  
Control Diet ◽  
Hepatic Triglyceride ◽  
Alcoholic Fatty Liver ◽  
Hepatic Lipid ◽  
Hepatic Lipid Accumulation

Abstract Enterohepatic circulation of 12α-hydroxylated (12αOH) bile acid (BA) is enhanced depending on the energy intake in high-fat diet-fed rats. Such BA metabolism can be reproduced using a diet supplemented with cholic acid (CA), which also induces simple steatosis, without inflammation and fibrosis, accompanied by some other symptoms that are frequently observed in the condition of non-alcoholic fatty liver in rats. We investigated whether supplementation of the diet with raffinose (Raf) improves hepatic lipid accumulation induced by the CA-fed condition in rats. After acclimation to the AIN-93-based control diet, male Wistar rats were fed diets supplemented with a combination of Raf (30 g/kg diet) and/or CA (0.5 g/kg diet) for 4 weeks. Dietary Raf normalised hepatic triglyceride levels (two-way ANOVA P<0.001 for CA, P=0.02 for Raf, and P=0.004 for interaction) in the CA-supplemented diet-fed rats. Dietary Raf supplementation reduced hepatic 12αOH BA concentration (two-way ANOVA P<0.001 for CA, P=0.003 for Raf, and P=0.03 for interaction). The concentration of 12αOH BA was reduced in the aortic and portal plasma. Raf supplementation increased acetic acid concentration in the caecal contents (two-way ANOVA P=0.001 as a main effect). Multiple regression analysis revealed that concentrations of aortic 12αOH BA and caecal acetic acid could serve as predictors of hepatic triglyceride concentration (R2=0.55, P<0.001). However, Raf did not decrease the secondary 12αOH BA concentration in the caecal contents as well as the transaminase activity in the CA diet-fed rats. These results imply that dietary Raf normalises hepatic lipid accumulation via suppression of enterohepatic 12αOH BA circulation.

scholarly journals N-Acetyl Cysteine Targets Hepatic Lipid Accumulation to Curb Oxidative Stress and Inflammation in NAFLD: A Comprehensive Analysis of the Literature

Antioxidants ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1283
Author(s):  
Phiwayinkosi V. Dludla ◽  
Bongani B. Nkambule ◽  
Sithandiwe E. Mazibuko-Mbeje ◽  
Tawanda M. Nyambuya ◽  
Fabio Marcheggiani ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Lipid Accumulation ◽  
Randomized Clinical Trials ◽  
Therapeutic Potential ◽  
Therapeutic Effects ◽  
Metabolic Complications ◽  
Alcoholic Fatty Liver ◽  
Hepatic Lipid ◽  
Hepatic Lipid Accumulation ◽  
Acetyl Cysteine

Impaired adipose tissue function and insulin resistance remain instrumental in promoting hepatic lipid accumulation in conditions of metabolic syndrome. In fact, enhanced lipid accumulation together with oxidative stress and an abnormal inflammatory response underpin the development and severity of non-alcoholic fatty liver disease (NAFLD). There are currently no specific protective drugs against NAFLD, and effective interventions involving regular exercise and healthy diets have proved difficult to achieve and maintain. Alternatively, due to its antioxidant and anti-inflammatory properties, there has been growing interest in understanding the therapeutic effects of N-acetyl cysteine (NAC) against metabolic complications, including NAFLD. Here, reviewed evidence suggests that NAC blocks hepatic lipid accumulation in preclinical models of NAFLD. This is in part through the effective regulation of a fatty acid scavenger molecule (CD36) and transcriptional factors such as sterol regulatory element-binding protein (SREBP)-1c/-2 and peroxisome proliferator-activated receptor gamma (PPARγ). Importantly, NAC appears effective in improving liver function by reducing pro-inflammatory markers such as interleukin (IL)-6 IL-1β, tumour necrosis factor alpha (TNF-α) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). This was primarily through the attenuation of lipid peroxidation and enhancements in intracellular response antioxidants, particularly glutathione. Very few clinical studies support the beneficial effects of NAC against NAFLD-related complications, thus well-organized randomized clinical trials are still necessary to confirm its therapeutic potential.

scholarly journals Lipoprotein-heparin-fibronectin-denatured collagen complexes enhance cholesteryl ester accumulation in macrophages.

1984 ◽  
Vol 99 (4) ◽  
pp. 1266-1274 ◽  
Author(s):  
D J Falcone ◽  
N Mated ◽  
H Shio ◽  
C R Minick ◽  
S D Fowler
Keyword(s):  
Extracellular Matrix ◽  
Cholesteryl Ester ◽  
Lipid Accumulation ◽  
Low Density Lipoprotein ◽  
Atherosclerotic Lesion ◽  
Density Lipoprotein ◽  
Cholesteryl Oleate ◽  
Peritoneal Macrophages ◽  
Ldl Catabolism ◽  
Cellular Lipid Accumulation

The sequestration of low-density lipoprotein (LDL) by components of the vascular extracellular matrix has long been recognized as a contributing factor to lipid accumulation during atherogenesis. The effects, however, that components of the extracellular matrix might have on LDL catabolism by scavenger cells have been little investigated. For these purposes we have prepared insoluble complexes of LDL, heparin, fibronectin, and denatured collagen (gelatin) and examined their effects on lipid accumulation, LDL uptake and degradation, and cholesteryl ester synthesis in mouse peritoneal macrophages. The results of these experiments have demonstrated that the cholesteryl ester content of macrophages incubated with a particular suspension of LDL, heparin, fibronectin, and collagen complexes is four- to fivefold that of cells incubated with LDL alone. The uptake of complexes containing 125I-LDL is rapid; however, in contrast to either endocytosed 125I-LDL or 125I-acetyl LDL, the degradation of complex-derived LDL is impaired. In addition, the uptake of complex-derived LDL stimulates the incorporation of [14C]oleic acid into cholesteryl oleate, however, the stimulation was a small fraction of that observed in cells incubated with acetyl LDL. Ultrastructurally, macrophages incubated with LDL, heparin, fibronectin, and collagen complexes did not contain many lipid droplets, but rather their cytoplasm is filled with phagosomes containing material similar in appearance to LDL-matrix complexes. These results indicate that components of the extracellular matrix can alter the catabolism of LDL by scavenger cells, suggesting that they may play a role in cellular lipid accumulation in the atherosclerotic lesion.

scholarly journals Epigenetic Regulation of Peroxisome Proliferator-Activated Receptor Gamma Mediates High-Fat Diet-Induced Non-Alcoholic Fatty Liver Disease

Cells ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1355
Author(s):  
Tahar Hajri ◽  
Mohamed Zaiou ◽  
Thomas V. Fungwe ◽  
Khadija Ouguerram ◽  
Samuel Besong
Keyword(s):  
Epigenetic Regulation ◽  
Lipid Accumulation ◽  
High Fat Diet ◽  
Target Genes ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Alcoholic Fatty Liver ◽  
Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is highly prevalent in Western countries and has become a serious public health concern. Although Western-style dietary patterns, characterized by a high intake of saturated fat, is considered a risk factor for NAFLD, the molecular mechanisms leading to hepatic fat accumulation are still unclear. In this study, we assessed epigenetic regulation of peroxisome proliferator-activated receptor γ (PPARγ), modifications of gene expression, and lipid uptake in the liver of mice fed a high-fat diet (HFD), and in hepatocyte culture challenged with palmitic acid. Bisulfate pyrosequencing revealed that HFD reduced the level of cytosine methylation in the pparγ DNA promoter. This was associated with increased expression of the hepatic PPARγ, very low-density lipoprotein receptor (VLDLR) and cluster differentiating 36 (CD36), and enhanced uptake of fatty acids and very low-density lipoprotein, leading to excess hepatic lipid accumulation. Furthermore, palmitic acid overload engendered comparable modifications in hepatocytes, suggesting that dietary fatty acids contribute to the pathogenesis of NAFLD through epigenetic upregulation of PPARγ and its target genes. The significance of epigenetic regulation was further demonstrated in hepatocytes treated with DNA methylation inhibitor, showing marked upregulation of PPARγ and its target genes, leading to enhanced fatty acid uptake and storage. This study demonstrated that HFD-induction of pparγ DNA promoter demethylation increased the expression of PPARγ and its target genes, vldlr and cd36, leading to excess lipid accumulation, an important initiating mechanism by which HFD increased PPARγ and lipid accumulation. These findings provide strong evidence that modification of the pparγ promoter methylation is a crucial mechanism of regulation in NAFLD pathogenesis.

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