Proteomic analysis of the inhibitory effect of epigallocatechin gallate on lipid accumulation in human HepG2 cells
TL;DR: The proteomic analysis hypothesized that EGCG reduced cellular lipid accumulation in FFA-induced HepG2 cells through the activation of AMP-activated protein kinase (AMPK) resulting from the generation of reactive oxygen species (ROS).
Abstract: Background
(−)-Epigallocatechin-3-gallate (EGCG), the most abundant catechin found in green tea, effectively reduces body weight and tissue and blood lipid accumulation. To explore the mechanism by which EGCG inhibits cellular lipid accumulation in free fatty acid (FFA) induced HepG2 cell culture, we investigated the proteome change of FFA-induced HepG2 cells exposed to EGCG using two-dimensional gel electrophoresis and mass spectrometry.
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TL;DR: The objectives of this paper are to review and discuss the currently known targets, signaling pathways and roles of EGCG that interfere with NAFLD pathogenesis, then providing additional experimental evidence and the foundation for the further studies and clinical applications of E GCG in the prevention and treatment ofNAFLD.
Abstract: Nonalcoholic fatty liver disease (NAFLD) is a major health issue throughout the world. However, no validated treatments for NAFLD are currently available. In-depth studies have demonstrated the efficacy of (-)-epigallocatechin-3-gallate (EGCG), a main bioactive chemical extracted from green tea, in treating NAFLD. EGCG exhibits multi-pronged preventive and therapeutic activities, including promoting lipid and glucose metabolism, anti-lipid peroxidation and anti-inflammation activities, anti-fibrosis, and anti-NAFLD related tumor, thus contributing to the mitigation of NAFLD occurrence and progression. The objectives of this paper are to review and discuss the currently known targets, signaling pathways and roles of EGCG that interfere with NAFLD pathogenesis, then providing additional experimental evidence and the foundation for the further studies and clinical applications of EGCG in the prevention and treatment of NAFLD.
40 citations
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TL;DR: Alkaloid and polyphenol are promising candidates for metabolic diseases to ameliorate lipid metabolism abnormalities to improve or even curing lipid metabolism-related diseases.
Abstract: Once the balance between lipid anabolism and catabolism is broken, metabolic disorder will occur in the organism and finally lead to metabolic diseases, such as nonalcoholic fatty liver disease (NAFLD), obesity and cancer. No established therapeutic regimens for treating NAFLD and obesity exist yet. Many natural compounds are extracted from botany, fungi and marine organisms. Importantly, natural compounds are major sources of innovative medicine. In this review, we first elucidate the important roles of lipid metabolism in NAFLD, obesity and cancer. Next, we summarize the action mechanisms of natural compounds including alkaloid, polyphenol targeting lipid metabolism. Therefore, manipulating lipid metabolism to reduce fatty acid availability may be the starting point for improving or even curing lipid metabolism-related diseases. Alkaloid and polyphenol are promising candidates for metabolic diseases to ameliorate lipid metabolism abnormalities.
19 citations
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TL;DR: The effects of ChrSd supplementation in a HF diet on weight gain, insulin resistance, and progression of hepatic steatosis in DIO mice were associated with modulation of hepatics genes related to oxidative stress, inflammation, ceramide synthesis, and lipid and cholesterol metabolism.
Abstract: To identify differentially expressed hepatic genes contributing to the improvement of high-fat (HF) diet-induced hepatic steatosis and insulin resistance following supplementation of partially defatted flavonoid-rich Chardonnay grape seed flour (ChrSd), diet-induced obese (DIO) mice were fed HF diets containing either ChrSd or microcrystalline cellulose (MCC, control) for 5 weeks. The 2-h insulin area under the curve was significantly lowered by ChrSd, indicating that ChrSd improved insulin sensitivity. ChrSd intake also significantly reduced body weight gain, liver and adipose tissue weight, hepatic lipid content, and plasma low-density lipoprotein (LDL)-cholesterol, despite a significant increase in food intake. Exon microarray analysis of hepatic gene expression revealed down-regulation of genes related to triglyceride and ceramide synthesis, immune response, oxidative stress, and inflammation and upregulation of genes related to fatty acid oxidation, cholesterol, and bile acid synthesis. In conclusion, the effects of ChrSd supplementation in a HF diet on weight gain, insulin resistance, and progression of hepatic steatosis in DIO mice were associated with modulation of hepatic genes related to oxidative stress, inflammation, ceramide synthesis, and lipid and cholesterol metabolism.
18 citations
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TL;DR: It is demonstrated that the extract of S. reticulata has therapeutic effects on obesity and metabolic disorders by enhancing lipogenesis genes and suppressing lipolysis genes through the activation of AMPKα in adipocytes.
Abstract: Salacia reticulata Wight (S. reticulata) is a herbal medicine used for treatment of early diabetes in Ayurvedic medicine. In previous reports, the extract of S. reticulata showed preventive effects on obesity and various metabolic disorders and a suppressive effect on differentiation in premature adipocytes. The aim of this research was to elucidate the therapeutic efficacy of the extract of S. reticulata on obesity and various metabolic disorders in 12-week-old TSOD mice with obesity and metabolic disorders and in mature 3T3-L1 adipocytes. In TSOD mice, S. reticulata therapy produced a reduction in body weight and mesenteric fat accumulation, an improvement in abnormal glucose metabolism, and an increase in adiponectin level in plasma. In addition, the mRNA expressions of hormone-sensitive lipase (HSL) and adiponectin were increased in mesenteric fat. In in vitro experiments, S. reticulata therapy produced suppression of intracellular triacylglycerol accumulation and enhancement of glycerol release into the medium in mature 3T3-L1 cells. The mRNA expressions of lipogenesis factor (peroxisome proliferator-activated receptor γ, lipoprotein lipase, CD36, and fatty acid binding protein 4) were down-regulated, while the expressions of lipolysis factor (adipose tissue triacylglycerol lipase and HSL) and adiponectin were up-regulated. Moreover, the extract of S. reticulata enhanced the expression of total AMP-activated protein kinase α (AMPKα) and phosphorylated AMPKα in mature adipocytes. These findings demonstrate that the extract of S. reticulata has therapeutic effects on obesity and metabolic disorders by enhancing lipogenesis genes and suppressing lipolysis genes through the activation of AMPKα in adipocytes.
12 citations
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TL;DR: The C. longa extract is suggested to have the anti-adipogenesis potential on inhibiting the synthesis of triglycerides and cholesterol and lipid droplet formation in HepG2 cell as anti-obesity parameters better than curcumin.
Abstract: Background: Adipocytes accumulate triacylglycerol when excessive food consumption. Adipocyte dysfunction plays an important role in the obesity development. People with a body weight 40 % heavier than the average body weight population at risk of death two times greater than the average body weight. The use of anti-obesity drugs have many side effects, so it is necessary to find the anti-obesity drug with low toxicity. This ex vivo study was conducted to determine the activity of C. longa L. extract in inhibiting triglycerides and cholesterol synthesis and lipid droplet formation on HepG2 cells compared to curcumin. Methods: Anti-obesity activity includes reduced formation of lipid droplet in HepG2 cells can be observed using oil red O staining method. The measurement of triglyceride level was performed according to Randox protocol using Randox TR 210 assay kit. Lipolytic activity by measuring cholesterol levels was performed based on Randox CH 200 kits. Results: This study suggested that the extract of C. longa L. and curcumin have potential anti-obesity compounds. C. longa L. extract have higher activity in inhibiting triglycerides and cholesterol synthesis compared to curcumin with inhibition activities 70.43% and 66.38% respectively in the highest concentration. Conclusion: The C. longa extract posses the anti-adipogenesis potential on inhibiting the synthesis of triglycerides and cholesterol and lipid droplet formation in HepG2 cell as anti-obesity parameters better than curcumin.
8 citations
References
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TL;DR: It is concluded that NAFLD, in the presence of normoglycemia and normal or moderately increased body weight, is characterized by clinical and laboratory data similar to those found in diabetes and obesity.
Abstract: Insulin sensitivity (euglycemic clamp, insulin infusion rate: 40 mU m(-2) min(-1)) was studied in 30 subjects with biopsy-proven nonalcoholic fatty liver disease (NAFLD), normal glucose tolerance, and a BMI <30 kg/m(2) Of those 30 subjects, 9 had pure fatty liver and 21 had evidence of steatohepatitis In addition, 10 patients with type 2 diabetes under good metabolic control and 10 healthy subjects were studied Most NAFLD patients had central fat accumulation, increased triglycerides and uric acid, and low HDL cholesterol, irrespective of BMI Glucose disposal during the clamp was reduced by nearly 50% in NAFLD patients, as well as in patients with normal body weight, to an extent similar to that of the type 2 diabetic patients Basal free fatty acids were increased, whereas insulin-mediated suppression of lipolysis was less effective (-69% in NAFLD vs -84% in control subjects; P = 0003) Postabsorptive hepatic glucose production (HGP), measured by [6,6-(2)H(2)]glucose, was normal In response to insulin infusion, HGP decreased by only 63% of basal in NAFLD vs 84% in control subjects (P = 0002) Compared with type 2 diabetic patients, NAFLD patients were characterized by lower basal HGP, but with similarly reduced insulin-mediated suppression of HGP There was laboratory evidence of iron overload in many NAFLD patients, but clinical, histological, and biochemical data (including insulin sensitivity) were not correlated with iron status Four subjects were heterozygous for mutation His63Asp of the HFE gene of familiar hemochromatosis We concluded that NAFLD, in the presence of normoglycemia and normal or moderately increased body weight, is characterized by clinical and laboratory data similar to those found in diabetes and obesity NAFLD may be considered an additional feature of the metabolic syndrome, with specific hepatic insulin resistance
2,258 citations
"Proteomic analysis of the inhibitor..." refers background in this paper
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TL;DR: A modified Neuhoff's colloidal Coomassie Blue G‐250 stain is reported, dubbed “blue silver” on account of its considerably higher sensitivity, approaching the one of conventional silver staining, and its full compatibility with mass spectrometry of eluted polypeptide chains is confirmed.
Abstract: A modified Neuhoff's colloidal Coomassie Blue G-250 stain is reported, dubbed "blue silver" on account of its considerably higher sensitivity, approaching the one of conventional silver staining. The main modifications, as compared to Neuhoff's protocol, were: a 20% increment in dye concentration (from 0.1% up to 0.12%) and a much higher level of phosphoric acid in the recipe (from 2% up to 10%). The "blue silver" exhibits a much faster dye uptake (80% during the first hour of coloration, vs. none with a commercial preparation from Sigma). Even at equilibrium (24 h staining), the "blue silver" exhibits a much higher sensitivity than all other recipes, approaching (but lower than) the one of the classical silver stain. Measurements of stain sensitivity after sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of bovine serum albumin (BSA) gave a detection limit (signal-to-noise ratio > 3) of 1 ng in a single zone. The somewhat lower sensitivity of "blue silver" as compared to classical silvering protocols in the presence of aldehydes is amply compensated for by its full compatibility with mass spectrometry of eluted polypeptide chains, after a two-dimensional map analysis, thus confirming that no dye is covalently bound (or permanently modifies) to any residue in the proteinaceous material. It is believed that the higher level of phosphoric acid in the recipe, thus its lower final pH, helps in protonating the last dissociated residues of Asp and Glu in the polypeptide coils, thus greatly favoring ionic anchoring of dye molecules to the protein moiety. Such a binding, though, must be followed by considerable hydrophobic association with the aromatic and hydrophobic residues along the polypeptide backbone.
1,753 citations
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TL;DR: This review examines the structural basis for 14-3- 3-ligand interactions, proposed functions of 14-1-3 in various signaling pathways, and emerging views of mechanisms that regulate 14-2-3 actions.
Abstract: The 14-3-3 proteins are a family of conserved regulatory molecules expressed in all eukaryotic cells. A striking feature of the 14-3-3 proteins is their ability to bind a multitude of functionally diverse signaling proteins, including kinases, phosphatases, and transmembrane receptors. This plethora of interacting proteins allows 14-3-3 to play important roles in a wide range of vital regulatory processes, such as mitogenic signal transduction, apoptotic cell death, and cell cycle control. In this review, we examine the structural basis for 14-3-3-ligand interactions, proposed functions of 14-3-3 in various signaling pathways, and emerging views of mechanisms that regulate 14-3-3 actions.
1,470 citations
"Proteomic analysis of the inhibitor..." refers background in this paper
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TL;DR: Skeletal muscle of trained endurance athletes is markedly insulin sensitive and has a high oxidative capacity, despite having an elevated lipid content, according to quantitative image analysis of Oil Red O staining.
Abstract: We examined the hypothesis that an excess accumulation of intramuscular lipid (IMCL) is associated with insulin resistance and that this may be mediated by the oxidative capacity of muscle. Nine sedentary lean (L) and 11 obese (O) subjects, 8 obese subjects with type 2 diabetes mellitus (D), and 9 lean, exercise-trained (T) subjects volunteered for this study. Insulin sensitivity (M) determined during a hyperinsulinemic (40 mU x m(-2)min(-1)) euglycemic clamp was greater (P < 0.01) in L and T, compared with O and D (9.45 +/- 0.59 and 10.26 +/- 0.78 vs. 5.51 +/- 0.61 and 1.15 +/- 0.83 mg x min(-1)kg fat free mass(-1), respectively). IMCL in percutaneous vastus lateralis biopsy specimens by quantitative image analysis of Oil Red O staining was approximately 2-fold higher in D than in L (3.04 +/- 0.39 vs. 1.40 +/- 0.28% area as lipid; P < 0.01). IMCL was also higher in T (2.36 +/- 0.37), compared with L (P < 0.01). The oxidative capacity of muscle determined with succinate dehydrogenase staining of muscle fibers was higher in T, compared with L, O, and D (50.0 +/- 4.4, 36.1 +/- 4.4, 29.7 +/- 3.8, and 33.4 +/- 4.7 optical density units, respectively; P < 0.01). IMCL was negatively associated with M (r = -0.57, P < 0.05) when endurance-trained subjects were excluded from the analysis, and this association was independent of body mass index. However, the relationship between IMCL and M was not significant when trained individuals were included. There was a positive association between the oxidative capacity and M among nondiabetics (r = 0.37, P < 0.05). In summary, skeletal muscle of trained endurance athletes is markedly insulin sensitive and has a high oxidative capacity, despite having an elevated lipid content. In conclusion, the capacity for lipid oxidation may be an important mediator of the association between excess muscle lipid accumulation and insulin resistance.
1,023 citations
"Proteomic analysis of the inhibitor..." refers background in this paper
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TL;DR: A fast and simple method to quantitate the extent of adipose conversion by staining the accumulated lipid with Oil red O and determining the amount of extracted dye at 510 nm is reported.
Abstract: Cultured 3T3-F442A cells differentiate into adipocytes and accumulate lipid droplets in the cytoplasm. When fat cells are stained with Oil red O, the degree of staining seems to be proportional to the extent of cell differentiation. We report here a fast and simple method to quantitate the extent of adipose conversion by staining the accumulated lipid with Oil red O and determining the amount of extracted dye at 510 nm. The results show that Oil red O specifically stains triglycerides and cholesteryl oleate but no other lipids. This technique is a valuable tool for processing large numbers of cell cultures or samples in which adipose differentiation and/or accumulated triglycerides is to be quantitated.
874 citations