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.
54 citations
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.
37 citations
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.
25 citations
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.
17 citations
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.
11 citations
References
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TL;DR: It is indicated that GTE are beneficial for improving endurance capacity and the hypothesis that the stimulation of fatty acid use is a promising strategy for improving Endurance capacity is supported.
Abstract: Green tea contains a high level of polyphenolic compounds known as catechins. We investigated the effects of green tea extract (GTE), which is rich in catechins, on endurance capacity, energy metabolism, and fat oxidation in BALB/c mice over a 10-wk period. Swimming times to exhaustion for mice fed 0.2-0.5% (wt/wt) GTE were prolonged by 8-24%. The effects were dose dependent and accompanied by lower respiratory quotients and higher rates of fat oxidation as determined by indirect calorimetry. In addition, feeding with GTE increased the level of beta-oxidation activity in skeletal muscle. Plasma lactate concentrations in mice fed GTE were significantly decreased after exercise, concomitant with increases in free fatty acid concentrations in plasma, suggesting an increased lipid use as an energy source in GTE-fed mice. Epigallocatechin gallate (EGCG), a major component of tea catechins, also enhanced endurance capacity, suggesting that the endurance-improving effects of GTE were mediated, at least in part, by EGCG. The beta-oxidation activity and the level of fatty acid translocase/CD36 mRNA in the muscle was higher in GTE-fed mice compared with control mice. These results indicate that GTE are beneficial for improving endurance capacity and support the hypothesis that the stimulation of fatty acid use is a promising strategy for improving endurance capacity.
202 citations
TL;DR: Prohibitin's evolutionary conservation and ubiquitous expression indicate that it is a fundamentally important gene; and current data suggest a functional role in such dissimilar processes as development, senescence, and tumor suppression.
201 citations
TL;DR: How the activation of AMPK by naturally occurring compounds could help to prevent the development of numerous diseases is discussed and the potential mechanism underlying these effects will also be addressed.
198 citations
"Proteomic analysis of the inhibitor..." refers background in this paper
...Activation of AMPK can induce ATP generation through glycolysis and β-oxidation, and suppress fatty acid and cholesterol syntheses, and gluconeogenesis [24]....
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TL;DR: The molecular mechanisms underlying the attenuating effect of (−)‐epigallocatechin‐3‐gallate (EGCG) on proliferation and lipid accumulation of 3T3‐L1 cells are investigated with a focus on the duration of EGCG treatment.
Abstract: MOON, HYUN-SEUK, CHUNG-SOO CHUNG, HONGGU LEE, TAE-GYU KIM, YUN-JAIE CHOI, AND CHONG-SU CHO. Inhibitory effect of ()epigallocatechin-3-gallate on lipid accumulation of 3T3-L1 cells. Obesity. 2007;15:2571–2582. Objective: The objective of this study was to investigate the molecular mechanisms underlying the attenuating effect of ()-epigallocatechin-3-gallate (EGCG) on proliferation and lipid accumulation of 3T3-L1 cells, with a focus on the duration of EGCG treatment. Research Methods and Procedures: Cell viability was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium assay and diamidino-2-phenylindole staining. The anti-adipogenic effect of EGCG on 3T3-L1 cells was analyzed by glycerol-3-phosphate dehydrogenase activity and Oil red O staining. Western blot analysis was used to detect adenosine monophosphate-activated protein kinase (AMPK) activation and phosphorylation of its substrate, acetyl-CoA carboxylase (ACC), and expression of insulin (INS) receptor, INS receptor substrate-1 (IRS-1), and adipocyte marker proteins. Results: Exposure to EGCG during the early period of adipogenesis (7 days) was sufficient to prevent lipid accumulation. During this period, EGCG greatly decreased expression of the adipocyte marker proteins peroxisome proliferator-activated receptor 2 (PPAR2) and liver X receptor (LXR)-. Furthermore, EGCG significantly induced generation of reactive oxygen species (ROS), which led to AMPK activation, and these effects were eliminated by N-acetylcysteine (NAC) treatment. Also, EGCG increased the tyrosine phosphorylation of INS receptor and INS-1 with increasing incubation time. In contrast, EGCG treatment did not alter glycerol release in the presence or absence of 2,5-dideoxyadenosine (DDA), indicating that EGCG had no effect on lipolysis. Discussion: Our data demonstrate that EGCG decreased cell viability and inhibited differentiation of 3T3-L1 cells in a manner dependent on the duration of treatment. Also, we showed that inhibition of adipocyte differentiation by EGCG was associated with decreased glycerol-3-phosphate dehydrogenase (GPDH) activity accompanied by a strong inhibition of PPAR2-induced transcriptional activity. Furthermore, the inhibition of adipocyte differentiation by EGCG involved generation of ROS and activation of AMPK.
198 citations
"Proteomic analysis of the inhibitor..." refers background in this paper
...EGCG significantly induced generation of ROS and reduced glutathione (GSH) in cells [21-23]....
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...Previous studies suggest that the inhibitory action of EGCG on lipid accumulation is mediated via the AMPactivated protein kinase (AMPK) pathway [21-23]....
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...However, these effects could be eliminated by ROS scavenger, N-acetylcysteine, treatment [22,23,28]....
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TL;DR: The data indicate that EGCG inhibits FAS activity as efficiently as presently known synthetic inhibitors and selectively causes apoptosis in LNCaP cells but not in nontumoral fibroblasts, which establishes EGCGs as a potent natural inhibitor of FAS in intact cells and strengthens the molecular basis for the use of E GCG as a chemopreventive and therapeutic antineoplastic agent.
Abstract: Chemical inhibitors of fatty acid synthase (FAS) inhibit growth and induce apoptosis in several cancer cell lines in vitro and in tumor xenografts in vivo. Recently the green tea component epigallocatechin-3-gallate (EGCG) was shown to act as a natural inhibitor of FAS in chicken liver extracts. Here we investigated whether EGCG inhibits FAS activity in cultured prostate cancer cells and how this inhibition affects endogenous lipid synthesis, cell proliferation and cell viability. The high levels of FAS activity in LNCaP cells were dose-dependently inhibited by EGCG and this inhibition was paralleled by decreased endogenous lipid synthesis, inhibition of cell growth and induction of apoptosis. In contrast, epicatechin (EC), another closely related green tea polyphenolic compound, which does not inhibit FAS, had no effect on LNCaP cell growth or viability. Treatment of nonmalignant cells with low levels of FAS activity (fibroblasts) with EGCG led to a decrease in growth rate but not to induction of apoptosis. These data indicate that EGCG inhibits FAS activity as efficiently as presently known synthetic inhibitors and selectively causes apoptosis in LNCaP cells but not in nontumoral fibroblasts. These findings establish EGCG as a potent natural inhibitor of FAS in intact cells and strengthen the molecular basis for the use of EGCG as a chemopreventive and therapeutic antineoplastic agent.
196 citations
"Proteomic analysis of the inhibitor..." refers background in this paper
...Moreover, EGCG treatment down-regulated several genes related to fatty acid synthesis and storage in the liver and white adipose tissue, including acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), malic enzyme (ME), glucose-6-phosphate dehydrogenase (G6PDH), glycerol-3 -phosphate dehydrogenase (G3PDH), and stearoyl-CoA desaturase-1 (SCD1) [12-15]....
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