Lipid Metabolism In HepG2 Cells Research Articles

Nutritional Evaluation of Almond Protein-Whey Protein Double System and Its Effect on Lipid Metabolism in HepG2 Cells

Almond protein (AP) and whey protein (WP) as single animal and plant proteins have certain limitations in nutrition, but the AP-WP dual protein can play a role in nutritional complementarity, and have a certain regulatory effect on lipid metabolism. This study investigated the amino acid composition of AP-WP system and its effect on FFA induced lipid metabolism in HepG2 cells. Results showed that, using the FAO/WHO model and whole egg protein model as reference values for essential amino acid content, the optimal mixing ratio of AP-WP was determined to be 3:5. The amino acid ratio coefficient scores under this ratio were 74.20 and 81.57 for the two models respectively. Additionally, this ratio of AP-WP showed the best antioxidant activity. The FT-IR spectroscopy indicated that there is interaction between AP and WP. The study found that AP-WP improved oxidative stress and lipid accumulation in HepG2 cells by reducing ROS and TG levels. Western blot analysis showed that AP-WP inhibits the expression of SREBP-1, FAS, and ACC, regulating lipid metabolism in HepG2 cells and leading to a certain lipid-lowering effect. The combination of almond protein and whey protein can improve the nutritional value of food and give full play to the physiological regulation of different proteins to promote human health. The research aims to lay the theoretical foundation for the application of double-protein system in the fields of nutritional food processing and lipid metabolism regulation.

Environmental monobutyl phthalate exposure promotes liver cancer via reprogrammed cholesterol metabolism and activation of the IRE1α-XBP1s pathway.

Humans are widely exposed to phthalates, a major chemical plasticizer that accumulates in the liver. However, little is known about the impact of chronic phthalate exposure on liver cancer development. In this study, we applied a long-term cell culture model by treating the liver cancer cell HepG2 and normal hepatocyte L02 to environmental dosage of monobutyl phthalate (MBP), the main metabolite of phthalates. Interestingly, we found that long-term MBP exposure significantly accelerated the growth of HepG2 cells in vitro and in vivo, but barely altered the function of L02 cells. MBP exposure triggered reprogramming of lipid metabolism in HepG2 cells, where cholesterol accumulation subsequently activated the IRE1α-XBP1s axis of the unfolded protein response. As a result, the XBP1s-regulated gene sets and pathways contributed to the increased aggressiveness of HepG2 cells. In addition, we also showed that MBP-induced cholesterol accumulation fostered an immunosuppressive microenvironment by promoting tumor-associated macrophage polarization toward the M2 type. Together, these results suggest that environmental phthalates exposure may facilitate liver cancer progression, and alerts phthalates exposure to patients who already harbor liver tumors.

Extracts of tropical green seaweed Caulerpa lentillifera reduce hepatic lipid accumulation by modulating lipid metabolism molecules in HepG2 cells

Seaweed has attracted attention as a bioactive source for preventing different chronic diseases, including liver injury and non-alcoholic fatty liver disease, the leading cause of liver-related mortality. Caulerpa lentillifera is characterized as tropical edible seaweed, currently being investigated for health benefits of its extracts and bioactive substances. This study examined the effects of C. lentillifera extract in ethyl acetate fraction (CLEA) on controlling lipid accumulation and lipid metabolism in HepG2 cells induced with oleic acid through the in vitro hepatic steatosis model. Gas chromatography-mass spectrometry (GC-MS) analysis indicated that CLEA contained diverse organic compounds, including hydrocarbons, amino acids, and carboxylic acids. Docked conformation of dl-2-phenyltryptophane and benzoic acid, two major bioactive CLEA components, showed high affinity binding to SIRT1 and AMPK as target molecules of lipid metabolism. CLEA reduced lipid accumulation and intracellular triglyceride levels in HepG2 cells stimulated with oleic acid. The effect of CLEA on regulating expression of lipid metabolism-related molecules was investigated by qPCR and immunoblotting. CLEA promoted expression of the SIRT1 gene in oleic acid-treated HepG2 cells. CLEA also reduced expression levels of SREBF1, FAS, and ACC genes, which might be related to activation of AMPK signaling in lipid-accumulated HepG2 cells. These findings suggest that CLEA contains bioactive compounds potentially reducing triglyceride accumulation in lipid-accumulated HepG2 hepatocytes by controlling lipid metabolism molecules.

Sesamin ameliorates lipotoxicity and lipid accumulation through the activation of the estrogen receptor alpha signaling pathway

Nonalcoholic fatty liver disease (NAFLD) has been linked to fat accumulation in the liver and lipid metabolism imbalance. Sesamin, a lignan commonly found in sesame seed oil, possesses antioxidant, anti-inflammatory, and anticancer properties. However, the precise mechanisms by which sesamin prevents hepatic steatosis are not well understood. This study aimed to explore the molecular mechanisms by which sesamin may improve lipid metabolism dysregulation. A in vitro hepatic steatosis model was established by exposing HepG2 cells to palmitate sodium. The results showed that sesamin effectively mitigated lipotoxicity and reduced reactive oxygen species production. Additionally, sesamin suppressed lipid accumulation by regulating key factors involved in lipogenesis and lipolysis, such as fatty acid synthase (FASN), sterol regulatory element–binding protein 1c (SREBP-1c), forkhead box protein O-1, and adipose triglyceride lipase. Molecular docking results indicated that sesamin could bind to estrogen receptor α (ERα) and reduce FASN and SREBP-1c expression via the Ca2+/calmodulin-dependent protein kinase kinase β (CaMKKβ)/AMP-activated protein kinase (AMPK) signaling pathway. Sesamin attenuated palmitate-induced lipotoxicity and regulated hepatic lipid metabolism in HepG2 cells by activating the ERα/CaMKKβ/AMPK signaling pathway. These findings suggest that sesamin can improve lipid metabolism disorders and is a promising candidate for treating hepatic steatosis.

Barley β-glucan inhibits digestion of soybean oil in vitro and lipid-lowering effects of digested products in cell co-culture model

The effect of barley β-glucan on soybean oil digestion characteristics before and after fermentation was studied in an in vitro–simulated gastrointestinal digestion model. The addition of barley β-glucan made the system more unstable, the particle size increased significantly, and confocal laser imaging showed that it was easier to form agglomerates. The addition of barley β-glucan increased the proportion of unsaturated fatty acids in digestion products, and reduced digestibility of soybean oil. In a co-culture model of Caco-2/HT29 and HepG2 cells, the effects of digestive products of soybean oil and barley β-glucan before and after fermentation on lipid metabolism in HepG2 cells were investigated. The results showed that adding only soybean oil digestion products significantly increased triglycerides (TG) content and lipid accumulation in basolateral HepG2 cells. When fermented barley β-glucan was added, lipid deposition was significantly decreased, and the lipid-lowering activity was better than that of unfermented barley β-glucan.

NDRG2 inhibits tumorigenesis of hepatocellular carcinoma by regulating metabolism of phospholipids and triglyceride: a metabonomic analysis

To explore the role of the tumor suppressor gene NDRG2 in regulating lipid metabolism in hepatoma cells. We analyzed the differential expression of NDRG2 gene between hepatocellular carcinoma tissues (n=809) and normal liver tissues (n=379) based on data from TNMplot database, and investigated the correlation between NDRG2 mRNA expression and the overall survival of the patients with hepatocellular carcinoma using THPA database, which was also used for analysis of NDRG2 expression levels in tumor cell lines for screening hepatoma cell lines. Human hepatoma cell line HepG2 was infected with a lentivirus containing NDRG2 cDNA, and the expression level of NDRG2 in the infected cells was detected using qPCR and Western blotting. Lipid metabolomics analysis was performed to analyze the regulatory effect of NDRG2 overexpression on lipid metabolism in HepG2 cells, and ELISA and Oil Red O staining were used to examine the changes in contents of phospholipids and triglyceride in NDRG2-overexpressing HepG2 cells. Analysis of the TNMplot database showed that NDRG2 expression level was significantly lower in hepatocellular carcinoma tissues than in normal liver tissues (P < 0.001). Analysis of THPA database showed that the patients with high NDRG2 mRNA levels had a longer survival time than those with low NDRG2 mRNA levels, and NDRG2 expression level was the highest in HepG2 cell line among the tumor cell lines. Metabolomics analysis showed that in HepG2 cells, NDRG2 overexpression led to changes in the contents of phospholipids, and among them lecithin PC, phosphatidyl glycerol PG, phosphatidyl ethanolamine PE, sphinophosphatidyl serine SM, and ceramide Cer exhibited significant changes. The results of ELISA and Oil Red O staining demonstrated that NDRG2 overexpression obviously reduced the contents of multiple phospholipids and significantly lowered the contents of triglyceride in HepG2 cells. NDRG2 regulates tumorigenesis of hepatocellular carcinoma by modulating the metabolism of phospholipids and triglyceride.

RF32 | PSUN44 CARF Regulates Non-Alcoholic Fatty Liver Diseases (NAFLD) by Controlling ER Stress and Lipogenesis in Hepatic Cells.

Abstract Background Sedentary lifestyles and changes in diet are fueling the worldwide epidemic of obesity and the prevalence of NAFLD and insulin resistance (IR). It has been predicted that NAFLD and its more advanced form, nonalcoholic steatohepatitis (NASH) will be the next epidemic in chronic liver diseases, and NAFLD/NASH will soon replace viral hepatitis as the primary cause of end-stage liver failure and transplantation. NAFLD is a significant risk factor for IR and cardiovascular diseases, and it highlights the importance of finding a way to control the epidemic. CARF is a multifunctional stress-responsive gene and was found to be reduced in response to metabolic stress in the fatty liver of diet-induced obesity mice (DIO). We also showed that CARF expression was down-regulated in palmitate (PA)-treated HepG2 cells. In this study, we aim to understand the consequences of the reduced expression of CARF on the development of NAFLD. Methods We performed RNA seq, RT-PCR and western blotting (WB) to evaluate the effect of CARF knockdown on lipid metabolism in HepG2 cells. Differentially expressed genes were analyzed by gene sort enrichment analysis (GSEA) and Ingenuity Pathway Analysis (IPA) to identify the metabolic pathways affected by CARF depletion. Apoptosis was assessed by TUNEL assay. To induce ER stress, HepG2 cells were treated with thapsigargin and evaluated its effect on CARF. Results By performing Sh-RNA mediated CARF knockdown, RNA-seq analysis, RT-PCR, western blotting (WB), we were able to show that ER-stress and de-novo lipogenesis pathways were significantly affected in HepG2 cells. We showed that GRP78, CHOP, PERK, ERN1a, genes associated with ER-stress were upregulated in CARF-depleted HepG2 cells. Additionally, thapsigargin-induced ER stress was found to reduce the expression of CARF along with the increased expression of ER stress marker genes. We also showed that overexpression of CARF mitigated the thapsigargin-induced ER stress suggesting that CARF protects against ER stress in HepG2 cells. In addition, the genes associated with triglyceride biosynthesis GPAT3, GPAM were significantly upregulated, indicating that lipogenesis was triggered by silencing of CARF in HepG2 cells. BODIPY staining and TG assay confirmed that silencing of CARF enhanced triglyceride biosynthesis in HepG2 cells. Furthermore, we showed that the expression of antioxidant genes GPX2, GPX3, and TXRND3 decreased, resulting in enhanced oxidative stress and higher apoptosis in CARF depleted cells. Conclusion We identified novel roles of CARF regulating cellular ER-Stress, lipid metabolism, and oxidative stress, and its impairment in response to metabolic stress could lead to the development of NAFLD in obese patients with metabolic abnormalities. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m., Monday, June 13, 2022 12:42 p.m. - 12:47 p.m.

Effect of Cudrania tricuspidata Water Extract on TNF-α-Induced Endoplasmic Reticulum Stress and Changes in Insulin Signaling and Lipid Metabolism in HepG2 Cells

Effect of <i>Cudrania tricuspidata </i>Water Extract on TNF-α-Induced Endoplasmic Reticulum Stress and Changes in Insulin Signaling and Lipid Metabolism in HepG2 Cells

Effects of Amino Acids Supplementation on Lipid and Glucose Metabolism in HepG2 Cells.

Non-alcoholic fatty liver disease and type 2 diabetes are representing symptoms of metabolic syndrome, which is often accompanied with hepatic fat accumulation and insulin resistance. Since liver is the major site of glucose and lipid metabolism, this study aimed to understand the effects of SCAAs and BCAAs supplementations on glucose and lipid metabolism in HepG2 cells. These cells were pretreated with SAMe, betaine, taurine, and BCAA for 24 h, followed by treatments of a high concentration of glucose (50 mM) or palmitic acid (PA, 0.5 mM) for 48 h to simulate high-glucose and high-fat environments. Pretreatment of BCAA and SCAAs inhibited the fat accumulation. At the transcriptional level, glucose and PA treatment led to significant increase of mRNA gluconeogenic enzyme. The mRNA expression level of GLUT2 was decreased by 20% in the SAMe-treated group and inhibited glucose synthesis by reducing the level of gluconeogenic enzyme. After SAMe or BCAA pretreatment, the mRNA expression of lipogenic enzymes was decreased. The PPAR-γ expression was increased after BCAA pretreatment, but SAMe not only downregulated the expression of PPAR-γ, but also inhibited the expression of ChREBP approximately 20% and SREBP-1c decreased by about 15%. Taken together, the effect of SAMe on glucose and lipid metabolism is significant especially on inhibiting hepatic lipogenesis and gluconeogenesis under the metabolic syndrome environment.

Copy Number Analyses Identified a Novel Gene: APOBEC3A Related to Lipid Metabolism in the Pathogenesis of Preeclampsia.

BackgroundPreeclampsia is a heterogeneous and complex disease with its pathogenesis mechanism not fully elucidated. A certain subset of patients with preeclampsia exhibit disturbances in lipid metabolism before clinical symptoms. Moreover, there is a tendency for preeclampsia to run in families. Whether genetic factors play a role in abnormal lipid metabolism during the incidence of preeclampsia has not been well investigated.MethodsPreeclampsia patients (n = 110) and healthy age- and gravidity-matched pregnant women (n = 110) were enrolled in this study. Peripheral blood specimens were used for genomic analysis (n = 10/group) or laboratory validation (n = 100/group). We retrospectively obtained the baseline clinical characteristics of 68 preeclampsia patients and 107 controls in early pregnancy (12–14 gestational weeks). Correlation analyses between differential genes and baseline lipid profiles were performed to identify candidate genes. In vitro and in vivo gain-of-function models were constructed with lentivirus and adeno-associated virus systems, respectively, to investigate the role of candidate genes in regulating lipid metabolism and the development of preeclampsia.ResultsWe observed that preeclampsia patients exhibited significantly elevated plasma TC (P = 0.037) and TG (P < 0.001) levels and increased body mass index (P = 0.006) before the disease onset. Within the region of 27 differential copy number variations, six genes potentially connected with lipid metabolism were identified. The aberrant copies of APOBEC3A, APOBEC3A_B, BTNL3, and LMF1 between preeclampsia patients and controls were verified by quantitative polymerase chain reaction. Especially, APOBEC3A showed a significant positive correlation with TC (P < 0.001) and LDL (P = 0.048) in early pregnancy. Then, our in vitro data revealed that overexpression of APOBEC3A disrupted lipid metabolism in HepG2 cells and affected both cholesterol and fatty acid metabolisms. Finally, in vivo study in a hepatic-specific overexpressed APOBEC3A mouse model revealed abnormal parameters related to lipid metabolism. Pregnant mice of the same model at the end of pregnancy showed changes related to preeclampsia-like symptoms, such as increases in sFlt-1 levels and sFlt-1/PLGF ratios in the placenta and decreases in fetal weight.ConclusionOur findings established a new link between genetics and lipid metabolism in the pathogenesis of preeclampsia and could contribute to a better understanding of the molecular mechanisms of preeclampsia.

The effect of black seed (Nigella sativa) extract on lipid metabolism in HepG2 cells

Black seed extract stimulates apolipoprotein A-I (apo A-I) gene expression in hepatocytes and intestinal cells in part by elevating peroxisome proliferator-activated receptor α (PPARα) and retinoid X receptor α (RXRα) levels. To explore potential ramifications of these observations, we examined the effects of black seed extract on hepatocyte lipid content and expression of key transcriptional regulators of fatty acid β-oxidation and lipogenesis in HepG2 cells. PPARα, peroxisome proliferator-activated receptor γ (PPARγ), RXRα, thyroid hormone receptor β (TRβ), sterol-responsive element binding protein 1 (SREBP1), and sterol-responsive element binding protein 2 (SREBP2) levels were measured in black seed extract treated liver-derived HepG2 cells. Black seed extract treatment increased PPARα and RXRα expression and decreased intracellular neutral lipid content. Black seed extract treatment increased TRβ expression and activity, and PPARα activity. In contrast, PPARγ, SREBP1 and SREBP2 levels were decreased in black seed extract treated cells. Black seed extract treatment also increased acyl-CoA synthetase long chain family member 5 (ACSL5), peroxisomal acyl-CoA oxidase 1 (ACOX1), and carnitine palmitoyl transferase 1A (CPT-1A) expression, three PPARα-dependent rate-limiting genes that facilitate fatty acid oxidation, similar to fenofibrate. PPARα knockdown reversed the effects of fenofibrate and blackseed on ACSL5, ACOX1, and CPT-1A expression. In conclusion, black seed extract-mediated lipid lowering in HepG2 cells is associated with increased expression of fatty acid oxidation enzymes and PPARα and reduced lipogenic signaling. Thus black seed extract may be potentially beneficial in metabolic diseases such as diabetes, cardiovascular disease, and metabolic syndrome.

Garcinia Biflavonoid 1 Improves Lipid Metabolism in HepG2 Cells via Regulating PPARα.

Garcinia biflavonoid 1 (GB1) is one of the active chemical components of Garcinia kola and is reported to be capable of reducing the intracellular lipid deposition, which is the most significant characteristic of non-alcoholic fatty liver disease. However, its bioactive mechanism remains elusive. In the current study, the lipid deposition was induced in HepG2 cells by exposure to oleic acid and palmitic acid (OA&PA), then the effect of GB1 on lipid metabolism and oxidative stress and the role of regulating PPARα in these cells was investigated. We found that GB1 could ameliorate the lipid deposition by reducing triglycerides (TGs) and upregulate the expression of PPARα and SIRT6, suppressing the cell apoptosis by reducing the oxidative stress and the inflammatory factors of ROS, IL10, and TNFα. The mechanism study showed that GB1 had bioactivity in a PPARα-dependent manner based on its failing to improve the lipid deposition and oxidative stress in PPARα-deficient cells. The result revealed that GB1 had significant bioactivity on improving the lipid metabolism, and its potential primary action mechanism suggested that GB1 could be a potential candidate for management of non-alcoholic fatty liver disease.

A Network Pharmacology Study on the Active Components and Targets of the Radix Ginseng and Radix Bupleuri Herb Pair for Treating Nonalcoholic Fatty Liver Disease.

Objective To explore the potential active components and corresponding target herb pairs of Radix Ginseng (Renshen) and Radix Bupleuri (Chaihu) in the treatment of nonalcoholic fatty liver disease (NAFLD) through network pharmacology and in vitro experiments. Methods The active components and potential targets of the herb pair of Renshen and Chaihu were screened through a network database system, and Venn analysis was performed with the obtained NAFLD targets. The intersecting targets were analysed for gene ontology (GO) functions and Kyoto Encyclopedia of Genes and Genome (KEGG) pathways, and a protein-protein interaction (PPI) network was generated. Cytoscape software was used to construct active component-target networks of the Renshen and Chaihu herb pair. Free fatty acids were added to the HepG2 cell line to create high-fat models that were treated with different concentrations of stigmasterol. The effect of stigmasterol on the lipid metabolism in HepG2 cells and PPARγ-knockdown cells was determined by oil red O staining, Nile red staining, and TG level. PPARγ and UCP-1 mRNA, and protein expression levels were detected by qRT-PCR and Western blot analyses, respectively. Results Twenty active components obtained from the Renshen and Chaihu herb pair were identified. The herb pair active component-target network showed that both Renshen and Chaihu contained stigmasterol and kaempferol as active components. The PPI network comprised 63 protein nodes. GO enrichment analysis and KEGG pathway enrichment analysis showed that the targets were mainly involved in lipid metabolism. Eight core targets were identified: AKT1, PPARG, MAPK3, TNF, TP53, SIRT1, STAT3, and PPARA. In vitro experiments demonstrated that stigmasterol reduced lipid accumulation and TG levels in HepG2 cells, and the mechanism may have been related to the activation of the PPARγ-UCP-1 signalling pathway. Conclusion This study preliminarily illustrated the potential components and corresponding core targets of the Renshen and Chaihu herb pair in treating NAFLD. The effect of stigmasterol on the PPARγ-UCP-1 signalling pathway in enhancing lipid metabolism may represent one of the mechanisms of the Renshen and Chaihu herb pair in the treatment of NAFLD. The results provide new evidence and research insights to reveal the roles of Renshen and Chaihu in the management of NAFLD.

Adipose tissue plays a major role in retinoic acid-mediated metabolic homoeostasis

ABSTRACT Retinoic acid (RA), a bioactive metabolite of vitamin A, has shown therapeutic effects in liver disease, and its effect in improving non-alcoholic fatty liver disease (NAFLD) is associated with the inhibition of adipogenesis in the white adipose tissue (WAT) and fatty acid oxidation induction in the liver. However, the major target organ of RA is unknown. We performed chronic administration of RA in high-fat diet (HFD)-induced NAFLD mice. Further, hepatic and adipose cells were used to study the direct effect of RA on lipid metabolism. In addition, qRT-PCR was performed to examine differential gene expression in mouse adipose tissue. RA administration ameliorated NAFLD in HFD-induced obese mice and increased mouse energy expenditure. Although RA had therapeutic effects on liver histology and lipid accumulation, it did not directly affect lipid metabolism in HepG2 cells. In contrast, RA reduced the weight of several adipose tissues and improved lipid accumulation in OP9 cells. In addition, RA upregulated genes responsible for fatty acid oxidation and thermogenesis in three different WATs. Our work suggests that the liver may not be the main target organ of RA during NAFLD treatment. WAT browning induced by RA may be the primary contributor towards the amelioration of NAFLD in HFD-induced obese mice.

Peptides released from bovine α-lactalbumin by simulated digestion alleviated free fatty acids-induced lipid accumulation in HepG2 cells

• Peptides from α-LA decreased lipid accumulation in HepG2 cells. • The peptides of P2 (GINY) and P8 (DQW) acted as PPARα ligands. • P2 and P8 up-regulated genes expression of fatty acid β-oxidation in HepG2 cells. • P2 and P8 down-regulated genes expression of lipogenesis in HepG2 cells. Our previous study showed that α-lactalbumin (α-LA) has a regulatory effect on lipid metabolism in obese mice. In this study, we performed simulated gastrointestinal digestion of α-LA to investigate the effect of peptides on lipid metabolism in HepG2 cells. The results showed that α-LA hydrolysate attenuated lipid accumulation and enhanced PPARα levels in HepG2 cells. Then, peptides from the hydrolysate were isolated and purified, and four PPARα-activating peptides (P2 (GINY), P8 (DQW), P13 (DQWL), P14 (LFQ)) were screened by molecular docking. Interestingly, P2 and P8 effectively improved intracellular TG and PPARα levels than P13 and P14. Furthermore, P2 and P8 acted as PPARα ligands to activate the PPARα signalling pathway, upregulate the expression of β-oxidation-related genes (PPARα, CPT-1a, ACOX1) and downregulate the expression of lipogenesis-related genes (ACC1, SCD-1, FASN), thereby improving lipid metabolism and reducing oxidative stress damage. Hence, α-LA shows promise as a functional food to ameliorate obesity.

Chemerin causes lipid metabolic imbalance and induces passive lipid accumulation in human hepatoma cell line via the receptor GPR1

AimsChemerin is abundant in patients with high body mass index and metabolic syndrome possibly due to its activation in adipogenesis and glucose intolerance. It has reported that sera chemerin is positively associated with fatty liver with little known underlying mechanisms. Our aim is to study the role of chemerin in hepatic lipid metabolism. Main methodsOil Red O staining and TG quantitative assay were used to detect intracellular lipid accumulation. PCR, QPCR and western blot were applied to measure lipid metabolism-related genes, CMKLR1, GPR1 and inflammation marker genes. Luciferase reporter assay was employed to uncover the down-regulation of proximate promoter activities of CMKLR1 and GPR1 by SREBP1c. Antibody neutralization assay was used to address the effects of chemerin on hepatic lipid synthesis. Key findingsOver-expression of chemerin led to passive lipid accumulation, in human hepatoma cell line HepG2. The disable form of chemerin (chemerin 21–158) and active chemerin (chemerin 21–157) performed strongly effects on lipid metabolism in HepG2 cells. Heterologous expression of CMKLR1 or G-protein coupled receptor1 (GPR1) played similar roles in hepatocyte lipid metabolism as chemerin. Chemerin exerted its effects on lipid metabolism via GPR1 in HepG2 cells. Furthermore, free fatty acids and high concentration insulin inhibited chemerin expression. Consistently, the key lipogenic transcription factor Sterol regulatory element binding protein 1c suppressed chemerin mRNA expression and proximate promoter activities of CMKLR1 and GPR1. SignificanceIt implied the existence of negative feed-back regulation and further confirmed the involvement of chemerin in hepatic lipid metabolism.

Effect of statins on lipid metabolism-related microRNA expression in HepG2 cells.

Statins are potent cholesterol-lowering drugs that prevent cardiovascular events. microRNAs (miRNAs) modulate the expression of genes involved in metabolic pathways and cardiovascular functions post-transcriptionally. This study explored the effects of statins on the expression of miRNAs and their target genes involved in lipid metabolism in HepG2 cells. HepG2 cells were treated with atorvastatin or simvastatin (0.1-10µM) for 24h. The expression of 84 miRNAs and nine target genes, selected by in silico studies, was measured by qPCR Array and TaqMan-qPCR, respectively. Five miRNAs were upregulated (miR-129, miR-143, miR-205, miR-381 and miR-495) and two downregulated (miR-29b and miR-33a) in atorvastatin-treated HepG2 cells. Simvastatin also downregulated miR-33a expression. Both statins upregulated LDLR, HMGCR, LRP1, and ABCG1, and downregulated FDFT1 and ABCB1, whereas only atorvastatin increased SCAP mRNA levels. In silico analysis of miRNA-mRNA interactions revealed a single network with six miRNAs modulating genes involved in lipogenesis and lipid metabolism. The statin-dysregulated miRNAs were predicted to target genes involved in cellular development and differentiation, regulation of metabolic process and expression of genes involved in inflammation, and lipid metabolism disorders contributing to metabolic and liver diseases. Atorvastatin-mediated miR-129, miR-143, miR-205, miR-381, and miR-495 upregulation, and miR-29b, and miR-33a downregulation, modulate the expression of target genes involved in lipogenesis and lipid metabolism. Thus, statins may prevent hepatic lipid accumulation and ameliorate dyslipidemia.

Effects of epoxy stearic acid on lipid metabolism in HepG2 cells.

In the present study, effects of cis-9,10-epoxystearic acid (ESA) generated by the thermal oxidation of oleic acid on HepG2 cells, including intracellular lipid accumulation, fatty acid composition, and lipid metabolism, were investigated. Our results revealed that ESA increased the number and size of cellular lipid droplets. Intracellular triacylglycerol and total cholesterol content demonstrated that ESA induced lipid accumulation in HepG2 cells in a dose- and time-dependent manner. Results of fatty acid composition further indicated that ESA could lead to intracellular lipid accumulation. Our results also revealed that ESA may suppress the fatty acid oxidation in peroxisomes and mitochondria, including PPARα, Cpt1α, and Acox1, whereas the expression of genes involved in lipid synthesis, including Srebp-1c and Scd1, was enhanced. These findings provide critical information on the effects of ESA on HepG2 cells, particularly lipid accumulation and metabolism, which is important for evaluating the biosafety of the oxidative product of oleic acid. PRACTICAL APPLICATION: The administration of cis-9,10-epoxystearic acid to HepG2 cells could lead to disorder of lipid metabolism of cells by enhancing the intracellular lipid content, as well as suppressing the fatty acid oxidation in peroxisomes and mitochondria. These findings could provide information for the evaluation of the biosafety of the oxidative product of oleic acid.

Berberine Improves Glucose and Lipid Metabolism in HepG2 Cells Through AMPKα1 Activation.

AimThis study is designed to investigate whether or not AMP-activated protein kinase α1 (AMPKα1) is required for natural product berberine (BBR) to improve glucose and lipid metabolism in HepG2 cells.MethodsAMPKα1 knocked-out (KO, AMPKα1-/-) cells were obtained by co-transfection of the CRISPR/Cas9 KO and HDR (homology-directed repair) plasmid into HepG2 cells, as well as subsequent screen with puromycin. The expression levels of target proteins or mRNAs were determined by western blot or real-time RT-PCR, respectively. Cellular AMPK activity, glucose consumption, lactate release, glucose production, and lipid accumulation were determined by kits.ResultsThe results showed that the AMPKα1 gene was successfully KO in HepG2 cells. In AMPKα1-/- cells, the protein expression of AMPKα1 and phosphorylated-AMPKα1 (p-AMPKα1) disappeared, the level of total AMPKα declined to about 45–50% of wild type (p < 0.01), while p-AMPKα level and AMPK activity were reduced to less than 10% of wild type (p < 0.001). BBR increased p-AMPKα1, p-AMPKα, AMPK activity, and stimulated glucose consumption, lactate release, inhibited glucose production in wild type HepG2 cells (p < 0.05 or p < 0.01). BBR also reduced intracellular lipid accumulation and suppressed the expression of lipogenic genes in oleic acid (OA) treated wild type HepG2 cells (p < 0.05 or p < 0.01). In AMPKα1-/- HepG2 cells, the stimulating effects of BBR on p-AMPKα1, p-AMPKα, AMPK activity, and its improving effects on glucose and lipid metabolism were completely abolished.ConclusionOur study proves that AMPKα1 plays a critical role for BBR to improve glucose and lipid metabolism in HepG2 cells. Our results will provide new information to further understand the molecular mechanisms of BBR.

P2X7 receptor-targeted regulation by tetrahydroxystilbene glucoside in alcoholic hepatosteatosis: A new strategy towards macrophage-hepatocyte crosstalk.

Regulating macrophage-hepatocyte crosstalk through P2X7 receptors has led to new pharmacological strategies to reverse alcoholic hepatosteatosis. We investigated how tetrahydroxystilbene glucoside (2354glu), isolated from Polygonum multiflorum, modulates macrophage-hepatocyte crosstalk during alcoholic hepatosteatosis. A model of alcoholic hepatosteatosis was established by giving ethanol intragastrically to C57BL/6 mice. HepG2 cells were incubated in conditioned medium from LPS+ATP-activated THP-1 human macrophages with silenced or overexpressed P2X7 receptors. THP-1 macrophages or mouse peritoneal macrophages were pretreated with 2354glu for 1 hr prior to LPS+ATP stimulation. Western blots, RT-PCR and immunohistochemical analysis were used, along with over-expression and silencing of P2X7 receptors. Knockdown or overexpression of P2X7 receptors in THP-1 macrophages affected release of mature IL-1β and, subsequently, modulated lipid metabolism in HepG2 cells via the LKB-AMPK pathway. 2354glu ameliorated alcoholic hepatosteatosis in mice by regulating LKB1-AMPK-SREBP1 pathway and its target genes. Suppression of P2X7 receptor activation by 2354glu inhibited IL-1β release and reduced macrophage and neutrophil infiltration. In macrophages stimulated with LPS+ATP, expression of P2X7 receptors, caspase-1 and NF-κB, release of IL-1β, calcium influx and PI uptake were reduced by 2354glu. SIRT1-LKB1-AMPK-SREBP1 axis-mediated lipid accumulation in HepG2 cells was reduced when they were cultured with conditioned media from LPS+ATP-activated THP-1 macrophages pretreated with 2354glu. Modulation of P2X7 receptors in macrophages regulated lipid accumulation in hepatocytes during alcoholic hepatosteatosis. 2354glu might be a promising candidate that targets P2X7 receptors in macrophages interacting with hepatocytes during alcoholic hepatosteatosis.