- Effects of Alpha-lipoic Acid on SREBP-1c Expression in HepG2 Cells.
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Tae Sung Yun, Ae Kyung Min, Nam Kyung Kim, Mi Kyung Kim, Ho Chan Cho, Hye Soon Kim, Jae Seok Hwang, Seong Yeol Ryu, Keun Gyu Park, In Kyu Lee
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J Korean Endocr Soc. 2008;23(1):27-34. Published online February 1, 2008
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DOI: https://doi.org/10.3803/jkes.2008.23.1.27
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 Abstract
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- BACKGROUND
Non-alcoholic fatty liver disease is common in patients with insulin resistance. Sterol regulatory element binding protein-1c (SREBP-1c) is a member of a family of transcription factors that have been recognized as key regulators for lipid accumulation in the liver that activate enzymes involved in the fatty acid biosynthetic pathway. This study was designed to evaluate whether alpha-lipoic acid (ALA) inhibits insulin-stimulated SREBP-1c expression. METHODS: We investigated the effects of ALA on insulin-stimulated SREBP-1c expression in a human hepatoma cell line (HepG2 cells) using Northern and Western blot analysis. We also examined the effect of ALA on the promoter activity of the SREBP-1c gene to examine whether ALA can affect SREBP-1c expression at the transcriptional level. To discern the mechanism by which ALA inhibits SREBP-1c expression, we examined the role of AMP-activated protein kinase (AMPK). RESULTS: Insulin increased the expression of SREBP-1c mRNA and protein in HepG2 cells in a dose depended manner. Co-treatment with ALA inhibited the insulin increased SREBP-1c expression in a dose-dependent manner. ALA also inhibited insulin-stimulated activation of the SREBP-1c promoter activity, indicating that ALA inhibited SREBP-1c expression at the transcriptional level. ALA increased phosphorylation of AMPK in HepG2 cells. Inhibition of the AMPK activity by compound C markedly reversed the inhibitory effects of ALA for insulin-stimulated SREBP-1c expression. These results suggest that ALA-induced suppression of SREBP-1c expression is at least in part mediated via AMPK activation. CONCLUSION: The present study suggests that ALA has an inhibitory effect on insulin-stimulated SREBP-1c expression. Therefore, further studies on the effects of ALA on hepatic steatosis in an animal model need to be performed.
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Citations
Citations to this article as recorded by  - Effects of an aqueous extract of purple sweet potato on nonalcoholic fatty liver in high fat/cholesterol-fed mice
You Jin Lee, Yoon Kyoung Yang, You Jin Kim, Oran Kwon
Journal of Nutrition and Health.2015; 48(1): 1. CrossRef - Effects of an aqueous extract of purple sweet potato on nonalcoholic fatty liver in high fat/cholesterol-fed mice
You Jin Lee, Yoon Kyoung Yang, You Jin Kim, Oran Kwon
Journal of Nutrition and Health.2015; 48(1): 1. CrossRef
- Association of Polymorphism in beta3-Adrenergic Receptor Gene with Fat Distribution.
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Tae Sung Yun, Yong Deuk Kim, Hye Soon Kim, Mi Jung Kim, Young Sung Suh, Jung Hyeok Kwon, Jin Soo Choi, Jung Guk Kim, Sung Woo Ha, Bo Wan Kim, Kyu Chang Won, Hyong Woo Lee, Ho Sang Shon, Ji Hyun Lee, Hyun Dae Yoon, Won Ho Kim, Young Gil Yun, In Kyu Lee
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J Korean Endocr Soc. 2003;18(2):184-192. Published online April 1, 2003
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Abstract
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- BACKGROUND
Reasons for obesity include environmental factors and, more largely so, genetic factors. There have been many studies on these genetic factors. So far, genes related to obesity such as Leptin, Uncoupling Protein(UCP), Peroxisome proliferator activated receptor-gamma(PPAR-gamma), and Beta3-adrener-gic receptor(beta3-AR) gene have been discovered. Among these, beta3-AR is expressed in visceral adipose tissue and is thought to contribute to the regulation of resting metabolic rate and lipolysis. The missense mutation of beta3-AR gene, resulting in replacement of tryptophan by arginine at position 64(Trp64Arg), is associated with decreased resting metabolic rate and weightgain. We performed this study to determine if Trp64Arg polymorphism of beta3-AR gene is associatedwith obesity in Koreans. METHOD: We investigated the relationship between the beta3-AR gene mutation and body mass index (BMI), waist circumference, hip circumference, waist to hip ratio(WHR), area of subcutaneous fat, area of visceral fat, visceral to subcutaneous fat ratio(VSR), and lipid profile. 198 subjects were included in this study of which 97 were of normal weight and 101 were obese. Anthropometric data was obtained from physical examination and medical records. RESULT: In the cases of beta3-AR gene mutation of the obese group, the ratio of Trp/Arg and Arg/Arg are 43% and 5%, respectively, which were higher than the normal group(36%, 1%), although a statistical significant was not found. There was significant difference in the are of subcutaneous fat. Normal group(Trp/Trp) measured at 213.9+/-109.6cm2 versus 244.0+/-127.7cm2 (Trp/Arg) and 323.9+/-189.9cm2(Arg/Arg) for the mutation groups. Circumference of waist, circumference of hip, WHR, area of visceral fat, and VSR were higher in the mutation groups than in normal subject, but not significantly different. CONCLUSION: These results suggest that a genetic mutation in the beta3-AR gene can affect body fat composition, and is associated with obesity in Korean adults.
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