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Kim JE, Park SJ, Yu MH, Lee SP. Effect of Ganoderma applanatum Mycelium Extract on the Inhibition of Adipogenesis in 3T3-L1 Adipocytes. J Med Food 2014; 17:1086-94. [DOI: 10.1089/jmf.2013.3036] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Ji-Eun Kim
- Department of Food Science and Technology, Keimyung University, Daegu, Korea
| | - Sung-Jin Park
- Department of Food Science and Technology, Keimyung University, Daegu, Korea
| | - Mi-Hee Yu
- Department of Food Science and Technology, Keimyung University, Daegu, Korea
| | - Sam-Pin Lee
- Department of Food Science and Technology, Keimyung University, Daegu, Korea
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Zhang GH, Lu JX, Chen Y, Zhao YQ, Guo PH, Yang JT, Zang RX. Comparison of the adipogenesis in intramuscular and subcutaneous adipocytes from Bamei and Landrace pigs. Biochem Cell Biol 2014; 92:259-67. [DOI: 10.1139/bcb-2014-0019] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Fat deposition is a complex process involving proliferation, differentiation, and lipogenesis of adipocytes. Bamei and Landrace are considered to represent fat- and lean-type pig breeds. Subcutaneous (SC) and intramuscular (IM) pre-adipocytes were cultured to compare the proliferation and lipogenesis in these breeds. The differentiated adipocytes were exposed to glucose or insulin to evaluate their effects on lipogenesis and lipogenic gene expression. Pre-adipocytes proliferated dramatically faster in SC vs. IM cells, and in Bamei vs. Landrace breeds. Lipogenesis and lipogenic gene expression had a greater increase in Bamei than in Landrace, and in SC vs. IM in the process of differentiation. Glucose markedly promoted lipogenesis and lipogenic gene expression in differentiated adipocytes. The stimulation of high-glucose levels on lipogenesis and ChREBP and lipogenic gene expression was higher in SC than IM adipocytes, and in Bamei vs. Landrace. Insulin largely increased SREBP-1c expression, however it modestly stimulated lipogenesis and lipogenic gene expression, and there was no difference between cell populationsor between breeds. These data demonstrated that regional and varietal differences obviously existed in the development of porcine adipocytes. The proliferation and differentiation capacity of pre-adipocytes, and the adipocyte lipogenesis stimulated by glucose, are stronger in Bamei than Landrace, and in SC vs. IM adipocytes independent of breed.
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Affiliation(s)
- Guo Hua Zhang
- College of Life Science and Engineering, Northwest University for Nationalities, 1 Xibei xin cun, Lanzhou 730030/Gansu Engineering Research Center for Animal Cell, Lanzhou 730030, China
| | - Jian Xiong Lu
- College of Life Science and Engineering, Northwest University for Nationalities, 1 Xibei xin cun, Lanzhou 730030/Gansu Engineering Research Center for Animal Cell, Lanzhou 730030, China
| | - Yan Chen
- College of Life Science and Engineering, Northwest University for Nationalities, 1 Xibei xin cun, Lanzhou 730030/Gansu Engineering Research Center for Animal Cell, Lanzhou 730030, China
| | - Yong Qing Zhao
- College of Life Science and Engineering, Northwest University for Nationalities, 1 Xibei xin cun, Lanzhou 730030/Gansu Engineering Research Center for Animal Cell, Lanzhou 730030, China
| | - Peng Hui Guo
- College of Life Science and Engineering, Northwest University for Nationalities, 1 Xibei xin cun, Lanzhou 730030/Gansu Engineering Research Center for Animal Cell, Lanzhou 730030, China
| | - Ju Tian Yang
- College of Life Science and Engineering, Northwest University for Nationalities, 1 Xibei xin cun, Lanzhou 730030/Gansu Engineering Research Center for Animal Cell, Lanzhou 730030, China
| | - Rong Xin Zang
- College of Life Science and Engineering, Northwest University for Nationalities, 1 Xibei xin cun, Lanzhou 730030/Gansu Engineering Research Center for Animal Cell, Lanzhou 730030, China
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Ardiyanti A, Abe T, Tameoka N, Kobayashi E, Shoji N, Ohtani Y, Suzuki K, Roh SG, Katoh K. Effects of growth hormone gene polymorphism on lipogenic gene expression levels in diaphragm tissues of Japanese black heifers. ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES 2014; 25:1055-62. [PMID: 25049663 PMCID: PMC4093005 DOI: 10.5713/ajas.2012.12029] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 05/01/2012] [Accepted: 04/04/2012] [Indexed: 11/27/2022]
Abstract
Two SNPs, i.e. L127V and T172M, of bovine growth hormone (GH) causing the presence of GH gene haplotypes A, B, and C was previously shown to alter intramuscular fatty acid (FA) composition in Japanese Black (JB) heifers. To determine the SNP effect on somatotropic hormone concentration and lipogenesis, we measured plasma GH, insulin, and insulin-like growth factor-1 (IGF-1) concentrations. We also measured mRNA levels of fatty acid synthase (FASN), stearoyl-coA desaturase (SCD), and sterol regulatory element binding proteins-1 (SREBP-1) and FA composition in diaphragm tissues. Heifers with genotype CC had the lowest plasma insulin concentration and FASN and SCD mRNA levels among genotypes. FASN mRNA levels in haplotype A tended to positively correlate with saturated FA (SFA) content and negatively correlated with C18:2 and unsaturated FA (USFA) contents. SCD mRNA levels in haplotype A positively correlated with monounsaturated FA (MUFA) contents and negatively correlated with C18:0 content. They also tended to positively correlate with C16:1, C18:1, and USFA contents and USFA/SFA ratio and negatively correlate with SFA content. Taken together, GH gene polymorphism affects the lipogenic genes expression levels and their relationships with fatty acid compositions in diaphragm tissues of JB heifers at 31 months of age.
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Affiliation(s)
| | - Tsuyoshi Abe
- National Livestock Breeding Center, Fukushima 961-8511, Japan
| | - Nanae Tameoka
- National Livestock Breeding Center, Fukushima 961-8511, Japan
| | - Eiji Kobayashi
- National Livestock Breeding Center, Fukushima 961-8511, Japan
| | - Noriaki Shoji
- Yamagata General Agricultural Research Center, Shinjo 996-0041, Japan
| | | | - Keiichi Suzuki
- Department of Animal Breeding and Genetics, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan
| | - Sang-Gun Roh
- National Livestock Breeding Center, Fukushima 961-8511, Japan
| | - Kazuo Katoh
- National Livestock Breeding Center, Fukushima 961-8511, Japan
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MORISHITA S, MOCHIZUKI K, GODA T. Bindings of ChREBP and SREBP1, and Histone Acetylation around the Rat Liver Fatty Acid Synthase Gene Are Associated with Induction of the Gene during the Suckling-Weaning Transition. J Nutr Sci Vitaminol (Tokyo) 2014; 60:94-100. [DOI: 10.3177/jnsv.60.94] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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55
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Kim KB, Jang SH. Anti-obesity effect of EGCG and glucosamine-6-phosphate through decreased expression of genes related to adipogenesis and cell cycle arrest in 3T3-L1 adipocytes. ACTA ACUST UNITED AC 2014. [DOI: 10.4163/jnh.2014.47.1.1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Kkot Byeol Kim
- Medical Research Institute, Seoul Medical Center, Seoul 131-865, Korea
| | - Seong hee Jang
- Department of Pediatrics, Seoul Medical Center, Seoul 131-865, Korea
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Chen YC, Zeng XY, He Y, Liu H, Wang B, Zhou H, Chen JW, Liu PQ, Gu LQ, Ye JM, Huang ZS. Rutaecarpine analogues reduce lipid accumulation in adipocytes via inhibiting adipogenesis/lipogenesis with AMPK activation and UPR suppression. ACS Chem Biol 2013; 8:2301-11. [PMID: 23962138 DOI: 10.1021/cb4003893] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Obesity is characterized by expansion of adipose tissue, which results from an increase in adipocyte number (adipogenesis) and adipocyte size (lipogenesis). A reversal of these processes has been suggested to be a potential antiobetic therapy. Rutaecarpine (Rut) and its novel analogues (R17 and R18) were identified to exert potent effect in reducing lipid accumulation during adipocyte differentiation in 3T3-L1 adipocytes with little cytotoxicity. All three compounds reduced lipid accumulation in a dose-dependent manner, while R17 and R18 exhibited much more potent inhibitory effects compared to that of Rut. Further studies showed that R17 suppressed both adipogenesis and lipogenesis during all stages of adipocyte differentiation as indicated by the reduced protein and mRNA levels of key regulators of adipogenesis/lipogenesis, including PPARγ, C/EBPα, SREBP-1c, ACC, FAS, and SCD-1. We next examined the effect of R17 on the UPR pathway and the results showed that the UPR markers (PERK, eIF2α, IRE1α, and spliced XBP1 mRNA) were all significantly reduced by R17. Further studies revealed that R17 persistently activated AMPK during differentiation, suggesting that the AMPK may be an upstream mechanism for the effect of R17 on adipogenesis and lipogenesis via the adipogenic/lipogenic markers and the UPR pathway. Finally, studies in fast/refeeding mice demonstrated that R17 administration was able to reduce epididymal fat mass and the levels of plasma TG and FFA in vivo. Our results suggest that rutaecarpine analogues may have therapeutic potential for obesity and related metabolic disorders. The mechanism involves the suppression of adipogenic/lipogenic proteins and the suppression of the UPR pathway possibly via the AMPK.
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Affiliation(s)
- Ying-Chun Chen
- School of Pharmaceutical Sciences and Institute of Medicinal Chemistry, Sun Yat-sen University, Guangzhou, China
| | - Xiao-Yi Zeng
- Molecular Pharmacology for Diabetes Group, Health Innovations Research Institute and School of Health Sciences, RMIT University, Melbourne, Victoria, Australia
| | - Yan He
- School of Pharmaceutical Sciences and Institute of Medicinal Chemistry, Sun Yat-sen University, Guangzhou, China
| | - Hong Liu
- School of Pharmaceutical Sciences and Institute of Medicinal Chemistry, Sun Yat-sen University, Guangzhou, China
| | - Bin Wang
- School of Pharmaceutical Sciences and Institute of Medicinal Chemistry, Sun Yat-sen University, Guangzhou, China
| | - Han Zhou
- School of Pharmaceutical Sciences and Institute of Medicinal Chemistry, Sun Yat-sen University, Guangzhou, China
| | - Jian-Wen Chen
- School of Pharmaceutical Sciences and Institute of Medicinal Chemistry, Sun Yat-sen University, Guangzhou, China
| | - Pei-Qing Liu
- School of Pharmaceutical Sciences and Institute of Medicinal Chemistry, Sun Yat-sen University, Guangzhou, China
| | - Lian-Quan Gu
- School of Pharmaceutical Sciences and Institute of Medicinal Chemistry, Sun Yat-sen University, Guangzhou, China
| | - Ji-Ming Ye
- Molecular Pharmacology for Diabetes Group, Health Innovations Research Institute and School of Health Sciences, RMIT University, Melbourne, Victoria, Australia
| | - Zhi-Shu Huang
- School of Pharmaceutical Sciences and Institute of Medicinal Chemistry, Sun Yat-sen University, Guangzhou, China
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The Korean Mistletoe (Viscum album coloratum) Extract Has an Antiobesity Effect and Protects against Hepatic Steatosis in Mice with High-Fat Diet-Induced Obesity. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:168207. [PMID: 23935653 PMCID: PMC3725881 DOI: 10.1155/2013/168207] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 04/14/2013] [Indexed: 01/07/2023]
Abstract
This study investigates the inhibitory effects of Korean mistletoe extract (KME) on adipogenic factors in 3T3-L1 cells and obesity and nonalcoholic fatty liver disease (NAFLD) in mice fed a high-fat diet. Male C57Bl/6 mice fed a high-fat diet were treated with KME (3 g/kg/day) for 15 weeks for the antiobesity and NAFLD experiments. Body weight and daily food intake were measured regularly during the experimental period. The epididymal pad was measured and liver histology was observed. The effects of KME on thermogenesis and endurance capacity were measured. The effects of KME on adipogenic factors were examined in 3T3-L1 cells. Body and epididymal fat pad weights were reduced in KME-treated mice, and histological examination showed an amelioration of fatty liver in KME-treated mice, without an effect on food consumption. KME potently induces mitochondrial activity by activating thermogenesis and improving endurance capacity. KME also inhibited adipogenic factors in vitro. These results demonstrate the inhibitory effects of KME on obesity and NAFLD in mice fed a high-fat diet. The effects appear to be mediated through an enhanced mitochondrial activity. Therefore, KME may be an effective therapeutic candidate for treating obesity and fatty liver caused by a high-fat diet.
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Høstmark AT, Lunde MSH, Haug A. Increased serum triglycerides and reduced HDL cholesterol in male rats after intake of ammonium chloride for 3 weeks. Lipids Health Dis 2013; 12:92. [PMID: 23800210 PMCID: PMC3699398 DOI: 10.1186/1476-511x-12-92] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 06/10/2013] [Indexed: 11/23/2022] Open
Abstract
Background Previous data suggested that intake of sodas and other acid beverages might be associated with increased levels of serum triglycerides, lowered HDL cholesterol, and increased formation of mono unsaturated fatty acids, which are the preferred ones for triglyceride synthesis. The present work is an extension of these studies. Methods Thirty male rats were divided into 3 groups. All groups were given the same food, but various beverages: water (W), ammonium chloride, 200 mmol/L (AC), or sodium bicarbonate, 200 mmol/L (SB). Serum triglycerides, HDL cholesterol, and the fatty acid distribution in total serum lipids were determined. Delta9-desaturase in serum lipids was estimated by the ratio of palmitoleic to palmitic acid, and by the oleic/stearic acid ratio. Correlation and ANOVA were used to study associations and group differences. Results After 3 weeks, the AC group had higher triglyceride concentration and higher Delta9 desaturase indexes, but lower serum HDL and body weight as compared with the SB and W groups. In each of the groups, the oleic acid/stearic acid ratio correlated positively with serum triglycerides; in the pooled group the correlation coefficient was r = 0.963, p<0.01. Conclusions Rats ingesting ammonium chloride as compared with sodium bicarbonate responded with increased desaturase indexes, increased serum triglycerides, and lowered HDL cholesterol concentration, thereby possibly contributing to explain the increased triglyceride concentration previously observed in subjects with a frequent intake of acid beverages, such as sodas containing carbonic acid, citric acid, and phosphoric acid.
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Zhu HJ, Ding HH, Deng JY, Pan H, Wang LJ, Li NS, Wang XQ, Shi YF, Gong FY. Inhibition of preadipocyte differentiation and adipogenesis by zinc-α2-glycoprotein treatment in 3T3-L1 cells. J Diabetes Investig 2013; 4:252-60. [PMID: 24843663 PMCID: PMC4015661 DOI: 10.1111/jdi.12046] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 10/29/2012] [Accepted: 11/27/2012] [Indexed: 12/19/2022] Open
Abstract
Aims/Introduction Zinc‐α2‐glycoprotein (ZAG) is associated with the loss of adipose tissue in cancer cachexia, and has recently been proposed to be a candidate factor in the regulation of bodyweight. The aim of the study was to investigate the effects of ZAG on the proliferation and differentiation of 3T3‐L1 preadipocytes. Materials and Methods 3‐(4,5‐Dimethylthiazol‐2‐yl) 2,5‐diphenyl tetrazolium bromide (MTT) spectrophotometry, Oil Red O staining, intracellular triglyceride assays, real‐time quantitative reverse transcription polymerase chain reaction and transient transfection methods were used to explore the action of ZAG. Results Ectopic ZAG expression significantly stimulates 3T3‐L1 cells proliferation in a dose‐ and time‐dependent manner. The maximum influence of ZAG on proliferation was 1.43‐fold higher than what was observed in control cells. This effect was observed 144 h after transfection with 0.16 μg of murine ZAG (mZAG) plasmid (P < 0.001). The intracellular lipids content in mZAG over‐expressing cells were decreased as much as 37% when compared with the control cells after differentiation (P < 0.05, P < 0.01). The messenger ribonucleic acid levels of peroxisome proliferators‐activated receptor‐γ (PPARγ), CCAAT enhancer‐binding protein‐α (C/EBPα) and the critical lipogenic gene, fatty acid synthase (FAS), are also downregulated by up to 50% in fully differentiated ZAG‐treated adipocytes. ZAG suppresses FAS messenger ribonucleic acid expression by reducing FAS promoter activity. Conclusions Zinc‐α2‐glycoprotein stimulates the proliferation and inhibits the differentiation of 3T3‐L1 murine preadipocytes. The inhibitory action of ZAG on cell differentiation might be a result of the attenuation of the expression of PPARγ, C/EBPα and the lipogenic‐specific enzyme FAS by reducing FAS promoter activity.
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Affiliation(s)
- Hui-Juan Zhu
- Department of Endocrinology Key Laboratory of Endocrinology of Ministry of Health Peking Union Medical College Hospital Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China
| | - Hui-Hua Ding
- Department of Endocrinology Key Laboratory of Endocrinology of Ministry of Health Peking Union Medical College Hospital Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China ; Department of Rheumatology Renji Hospital, School of Medicine Shanghai Jiao Tong University Shanghai China
| | - Jie-Ying Deng
- Department of Endocrinology Key Laboratory of Endocrinology of Ministry of Health Peking Union Medical College Hospital Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China
| | - Hui Pan
- Department of Endocrinology Key Laboratory of Endocrinology of Ministry of Health Peking Union Medical College Hospital Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China
| | - Lin-Jie Wang
- Department of Endocrinology Key Laboratory of Endocrinology of Ministry of Health Peking Union Medical College Hospital Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China
| | - Nai-Shi Li
- Department of Endocrinology Key Laboratory of Endocrinology of Ministry of Health Peking Union Medical College Hospital Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China
| | - Xiang-Qing Wang
- Department of Endocrinology Key Laboratory of Endocrinology of Ministry of Health Peking Union Medical College Hospital Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China
| | - Yi-Fan Shi
- Department of Endocrinology Key Laboratory of Endocrinology of Ministry of Health Peking Union Medical College Hospital Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China
| | - Feng-Ying Gong
- Department of Endocrinology Key Laboratory of Endocrinology of Ministry of Health Peking Union Medical College Hospital Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China
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Wang Y, Wong RHF, Tang T, Hudak CS, Yang D, Duncan RE, Sul HS. Phosphorylation and recruitment of BAF60c in chromatin remodeling for lipogenesis in response to insulin. Mol Cell 2012; 49:283-97. [PMID: 23219531 DOI: 10.1016/j.molcel.2012.10.028] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Revised: 08/19/2012] [Accepted: 10/25/2012] [Indexed: 12/17/2022]
Abstract
Fatty acid and triglyceride synthesis is induced in response to feeding and insulin. This lipogenic induction involves coordinate transcriptional activation of lipogenic enzymes, including fatty acid synthase and glycerol-3-phosphate acyltransferase. We recently reported the importance of USF-1 phosphorylation and subsequent acetylation in insulin-induced lipogenic gene activation. Here, we show that Brg1/Brm-associated factor (BAF) 60c is a specific chromatin remodeling component for lipogenic gene transcription in liver. In response to insulin, BAF60c is phosphorylated at S247 by atypical PKCζ/λ, which causes translocation of BAF60c to the nucleus and allows a direct interaction of BAF60c with USF-1 that is phosphorylated by DNA-PK and acetylated by P/CAF. Thus, BAF60c is recruited to form the lipoBAF complex to remodel chromatin structure and to activate lipogenic genes. Consequently, BAF60c promotes lipogenesis in vivo and increases triglyceride levels, demonstrating its role in metabolic adaption to activate the lipogenic program in response to feeding and insulin.
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Affiliation(s)
- Yuhui Wang
- Department of Nutritional Science and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA
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Agassandian M, Mallampalli RK. Surfactant phospholipid metabolism. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:612-25. [PMID: 23026158 DOI: 10.1016/j.bbalip.2012.09.010] [Citation(s) in RCA: 153] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Revised: 09/07/2012] [Accepted: 09/16/2012] [Indexed: 12/16/2022]
Abstract
Pulmonary surfactant is essential for life and is composed of a complex lipoprotein-like mixture that lines the inner surface of the lung to prevent alveolar collapse at the end of expiration. The molecular composition of surfactant depends on highly integrated and regulated processes involving its biosynthesis, remodeling, degradation, and intracellular trafficking. Despite its multicomponent composition, the study of surfactant phospholipid metabolism has focused on two predominant components, disaturated phosphatidylcholine that confers surface-tension lowering activities, and phosphatidylglycerol, recently implicated in innate immune defense. Future studies providing a better understanding of the molecular control and physiological relevance of minor surfactant lipid components are needed. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.
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Affiliation(s)
- Marianna Agassandian
- Department of Medicine, Acute Lung Injury Center of Excellence, the University of Pittsburgh, Pittsburgh, PA 15213, USA
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Do MT, Kim HG, Choi JH, Khanal T, Park BH, Tran TP, Hwang YP, Na M, Jeong HG. Phillyrin attenuates high glucose-induced lipid accumulation in human HepG2 hepatocytes through the activation of LKB1/AMP-activated protein kinase-dependent signalling. Food Chem 2012; 136:415-25. [PMID: 23122079 DOI: 10.1016/j.foodchem.2012.09.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 08/28/2012] [Accepted: 09/05/2012] [Indexed: 12/31/2022]
Abstract
Phillyrin, an active constituent found in many medicinal plants and certain functional foods, has anti-obesity activity in vivo. The aim of our study was to provide new data on the molecular mechanism(s) underlying the role of phillyrin in the prevention of high glucose-induced lipid accumulation in human HepG2 hepatocytes. We found that phillyrin suppressed high glucose-induced lipid accumulation in HepG2 cells. Phillyrin strongly inhibited high glucose-induced fatty acid synthase (FAS) expression by modulating sterol regulatory element-binding protein-1c (SREBP-1c) activation. Moreover, use of the pharmacological AMP-activated protein kinase (AMPK) inhibitor compound C revealed that AMPK is essential for suppressing SREBP-1c expression in phillyrin-treated cells. Finally, we found that liver kinase B1 (LKB1) phosphorylation is required for the phillyrin-enhanced activation of AMPK in HepG2 hepatocytes. These results indicate that phillyrin prevents lipid accumulation in HepG2 cells by blocking the expression of SREBP-1c and FAS through LKB1/AMPK activation, suggesting that phillyrin is a novel AMPK activator with a role in the prevention and treatment of obesity.
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Affiliation(s)
- Minh Truong Do
- Department of Toxicology, College of Pharmacy, Chungnam National University, Daejeon 305-764, South Korea
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Mennigen JA, Panserat S, Larquier M, Plagnes-Juan E, Medale F, Seiliez I, Skiba-Cassy S. Postprandial regulation of hepatic microRNAs predicted to target the insulin pathway in rainbow trout. PLoS One 2012; 7:e38604. [PMID: 22701681 PMCID: PMC3368902 DOI: 10.1371/journal.pone.0038604] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 05/11/2012] [Indexed: 01/22/2023] Open
Abstract
Rainbow trout are carnivorous fish and poor metabolizers of carbohydrates, which established this species as a model organism to study the comparative physiology of insulin. Following the recent characterisation of key roles of several miRNAs in the insulin action on hepatic intermediary metabolism in mammalian models, we investigated the hypothesis that hepatic miRNA expression is postprandially regulated in the rainbow trout and temporally coordinated in the context of insulin-mediated regulation of metabolic gene expression in the liver. To address this hypothesis, we used a time-course experiment in which rainbow trout were fed a commercial diet after short-term fasting. We investigated hepatic miRNA expression, activation of the insulin pathway, and insulin regulated metabolic target genes at several time points. Several miRNAs which negatively regulate hepatic insulin signaling in mammalian model organisms were transiently increased 4 h after the meal, consistent with a potential role in acute postprandial negative feed-back regulation of the insulin pathway and attenuation of gluconeogenic gene expression. We equally observed a transient increase in omy- miRNA-33 and omy-miRNA-122b 4 h after feeding, whose homologues have potent lipogenic roles in the liver of mammalian model systems. A concurrent increase in the activity of the hepatic insulin signaling pathway and the expression of lipogenic genes (srebp1c, fas, acly) was equally observed, while lipolytic gene expression (cpt1a and cpt1b) decreased significantly 4 h after the meal. This suggests lipogenic roles of omy-miRNA-33 and omy-miRNA-122b may be conserved between rainbow trout and mammals and that these miRNAs may furthermore contribute to acute postprandial regulation of de novo hepatic lipid synthesis in rainbow trout. These findings provide a framework for future research of miRNA regulation of hepatic metabolism in trout and will help to further elucidate the metabolic phenotype of rainbow trout.
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Affiliation(s)
- Jan A. Mennigen
- UMR1067 Nutrition, Métabolisme, Aquaculture, Institut National de la Recherche Agronomique, Saint-Pée-sur-Nivelle, Pyrénées-Atlantiques, France
| | - Stéphane Panserat
- UMR1067 Nutrition, Métabolisme, Aquaculture, Institut National de la Recherche Agronomique, Saint-Pée-sur-Nivelle, Pyrénées-Atlantiques, France
| | - Mélanie Larquier
- UMR1067 Nutrition, Métabolisme, Aquaculture, Institut National de la Recherche Agronomique, Saint-Pée-sur-Nivelle, Pyrénées-Atlantiques, France
| | - Elisabeth Plagnes-Juan
- UMR1067 Nutrition, Métabolisme, Aquaculture, Institut National de la Recherche Agronomique, Saint-Pée-sur-Nivelle, Pyrénées-Atlantiques, France
| | - Françoise Medale
- UMR1067 Nutrition, Métabolisme, Aquaculture, Institut National de la Recherche Agronomique, Saint-Pée-sur-Nivelle, Pyrénées-Atlantiques, France
| | - Iban Seiliez
- UMR1067 Nutrition, Métabolisme, Aquaculture, Institut National de la Recherche Agronomique, Saint-Pée-sur-Nivelle, Pyrénées-Atlantiques, France
| | - Sandrine Skiba-Cassy
- UMR1067 Nutrition, Métabolisme, Aquaculture, Institut National de la Recherche Agronomique, Saint-Pée-sur-Nivelle, Pyrénées-Atlantiques, France
- * E-mail:
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Wu T, Sun L, ZhuGe F, Guo X, Zhao Z, Tang R, Chen Q, Chen L, Kato H, Fu Z. Differential roles of breakfast and supper in rats of a daily three-meal schedule upon circadian regulation and physiology. Chronobiol Int 2012; 28:890-903. [PMID: 22080734 DOI: 10.3109/07420528.2011.622599] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The timing of meals has been suggested to play an important role in circadian regulation and metabolic health. Three meals a day is a well-established human feeding habit, which in today's lifestyle may or may not be followed. The aim of this study was to test whether the absence of breakfast or supper significantly affects the circadian system and physiological function. The authors developed a rat model for their daily three meals study, whereby animals were divided into three groups (three meals, TM; no first meal, NF; no last meal, NL) all fed with the same amount of food every day. Rats in the NF group displayed significantly decreased levels of plasma triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and glucose in the activity phase, accompanied by delayed circadian phases of hepatic peripheral clock and downstream metabolic genes. Rats in the NL group showed lower concentration of plasma TC, HDL-C, and glucose in the rest phase, plus reduced adipose tissue accumulation and body weight gain. Real-time polymerase chain reaction (PCR) analysis indicated an attenuated rhythm in the food-entraining pathway, including down-regulated expression of the clock genes Per2, Bmal1, and Rev-erbα, which may further contribute to the delayed and decreased expression of FAS in lipogenesis in this group. Our findings are consistent with the conclusion that the daily first meal determines the circadian phasing of peripheral clocks, such as in the liver, whereas the daily last meal tightly couples to lipid metabolism and adipose tissue accumulation, which suggests differential physiological effects and function of the respective meal timings.
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Affiliation(s)
- Tao Wu
- College of Biological and Environmental Engineering , Zhejiang University of Technology, Hangzhou, China
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65
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Jensen-Urstad APL, Semenkovich CF. Fatty acid synthase and liver triglyceride metabolism: housekeeper or messenger? Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:747-53. [PMID: 22009142 DOI: 10.1016/j.bbalip.2011.09.017] [Citation(s) in RCA: 243] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 09/26/2011] [Accepted: 09/27/2011] [Indexed: 01/14/2023]
Abstract
Fatty acid synthase (FAS) catalyzes the de novo synthesis of fatty acids. In the liver, FAS has long been categorized as a housekeeping protein, producing fat for storage of energy when nutrients are present in excess. Most previous studies of FAS regulation have focused on the control of gene expression. However, recent findings suggest that hepatic FAS may also be involved in signaling processes that include activation of peroxisome proliferator-activated receptor α (PPARα). Moreover, reports of rapid alterations in FAS activity as well as findings of post-translational modifications of the FAS protein support the notion that dynamic events in addition to transcription impact FAS regulation. These results indicate that FAS enzyme activity can impact liver physiology through signaling as well as energy storage and that its regulation may be complex. This article is part of a Special Issue entitled Triglyceride Metabolism and Disease.
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Affiliation(s)
- Anne P L Jensen-Urstad
- Division of Endocrinology, Metabolism & Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
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66
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Cruz-Garcia L, Sánchez-Gurmaches J, Gutiérrez J, Navarro I. Regulation of LXR by fatty acids, insulin, growth hormone and tumor necrosis factor-α in rainbow trout myocytes. Comp Biochem Physiol A Mol Integr Physiol 2011; 160:125-36. [DOI: 10.1016/j.cbpa.2011.05.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Revised: 05/15/2011] [Accepted: 05/17/2011] [Indexed: 01/27/2023]
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67
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Liver X Receptor: an oxysterol sensor and a major player in the control of lipogenesis. Chem Phys Lipids 2011; 164:500-14. [PMID: 21693109 DOI: 10.1016/j.chemphyslip.2011.06.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 06/04/2011] [Accepted: 06/06/2011] [Indexed: 01/12/2023]
Abstract
De novo fatty acid biosynthesis is also called lipogenesis. It is a metabolic pathway that provides the cells with fatty acids required for major cellular processes such as energy storage, membrane structures and lipid signaling. In this article we will review the role of the Liver X Receptors (LXRs), nuclear receptors that sense oxysterols, in the transcriptional regulation of genes involved in lipogenesis.
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68
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Kong CS, Lee JI, Kim JA, Seo Y. In vitro evaluation on the antiobesity effect of lignans from the flower buds of Magnolia denudata. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2011; 59:5665-5670. [PMID: 21462973 DOI: 10.1021/jf200230s] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In the present study, an attempt has been made to isolate antiobesity components from crude extracts of the flower buds of Magnolia denudata by CH(2)Cl(2) and MeOH solvents. The crude extracts were partitioned into n-hexane, 85% aqueous MeOH, n-butanol, and water fractions. Their antiobesity effects were evaluated by measuring the effect on adipogenic differentiation using 3T3-L1 cells. Among the fractions, n-hexane and 85% aqueous MeOH fractions effectively reduced the lipid accumulation and the regulation of the adipogenic transcription factor. Both n-hexane and 85% aqueous MeOH fractions were further separated by diverse chromatographic methods to give four lignans (A-D). In comparative analysis, the presence of the lignans during adipogenic differentiation reduced the absorbance values of eluted Oil Red O solution in the order of potency C > D > B > A. Moreover, C and D effectively downregulated SREBP1, PPARγ, and C/EBPα.
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Affiliation(s)
- Chang-Suk Kong
- Department of Food and Nutrition, College of Medical and Life Science, Silla University, Busan, Republic of Korea
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69
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Wong RHF, Sul HS. Insulin signaling in fatty acid and fat synthesis: a transcriptional perspective. Curr Opin Pharmacol 2011; 10:684-91. [PMID: 20817607 DOI: 10.1016/j.coph.2010.08.004] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2010] [Revised: 08/05/2010] [Accepted: 08/09/2010] [Indexed: 02/04/2023]
Abstract
Transcription of enzymes involved in FA and TAG synthesis is coordinately induced in lipogenic tissues by feeding and insulin treatment. The three major transcription factors involved are USF, SREBP-1c, and LXRα. New insights into the insulin-signaling pathway(s) that control(s) lipogenic gene transcription via these factors have recently been revealed. Dephosphorylation/activation of DNA-PK by PP1 causes phosphorylation of USF that in turn recruits P/CAF to be acetylated for transcriptional activation. SREBP-1c can be induced by mTORC1, bifurcating lipogenesis from AKT-activated gluconeogenesis. LXRα may serve as a glucose sensor and, along with ChREBP, may activate lipogenic genes in the fed state. Dysregulation of FA and TAG metabolism often contributes to metabolic diseases such as obesity, diabetes, and cardiovascular diseases. Transcription factors and signaling molecules involved in transcriptional activation of FA and TAG synthesis represent attractive targets for the prevention and treatment of metabolic diseases.
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Affiliation(s)
- Roger H F Wong
- Department of Nutritional Science and Toxicology, and Comparative Biochemistry Program, University of California, Berkeley, CA 94720, USA
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70
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Kong X, Shen Y, Jiang N, Fei X, Mi J. Emerging roles of DNA-PK besides DNA repair. Cell Signal 2011; 23:1273-80. [PMID: 21514376 DOI: 10.1016/j.cellsig.2011.04.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2010] [Revised: 03/13/2011] [Accepted: 04/04/2011] [Indexed: 10/24/2022]
Abstract
The DNA-dependent protein kinase (DNA-PK) is a DNA-activated serine/threonine protein kinase, and abundantly expressed in almost all mammalian cells. The roles of DNA-PK in DNA-damage repair pathways, including non-homologous end-joining (NHEJ) repair and homologous recombinant (HR) repair, have been studied intensively. However, the high levels of DNA-PK in human cells are somewhat paradoxical in that it does not impart any increased ability to repair DNA damage. If DNA-PK essentially exceeds the demand for DNA damage repair, why do human cells universally express such high levels of this huge complex? DNA-PK has been recently reported to be involved in metabolic gene regulation in response to feeding/insulin stimulation; our studies have also suggested a role of DNA-PK in the regulation of the homeostasis of cell proliferation. These novel findings expand our horizons about the importance of DNA-PK.
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Affiliation(s)
- Xianming Kong
- Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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71
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Poupeau A, Postic C. Cross-regulation of hepatic glucose metabolism via ChREBP and nuclear receptors. Biochim Biophys Acta Mol Basis Dis 2011; 1812:995-1006. [PMID: 21453770 DOI: 10.1016/j.bbadis.2011.03.015] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 03/21/2011] [Accepted: 03/22/2011] [Indexed: 01/17/2023]
Abstract
There is a worldwide epidemic of obesity and type 2 diabetes, two major public health concerns associated with alterations in both insulin and glucose signaling pathways. Glucose is not only an energy source but also controls the expression of key genes involved in energetic metabolism, through the glucose-signaling transcription factor, Carbohydrate Responsive Element Binding Protein (ChREBP). ChREBP has emerged as a central regulator of de novo fatty acid synthesis (lipogenesis) in response to glucose under both physiological and physiopathological conditions. Glucose activates ChREBP by regulating its entry from the cytosol to the nucleus, thereby promoting its binding to carbohydrate responsive element (ChoRE) in the promoter regions of glycolytic (L-PK) and lipogenic genes (ACC and FAS). We have previously reported that the inhibition of ChREBP in liver of obese ob/ob mice improves the metabolic alterations linked to obesity, fatty liver and insulin-resistance. Therefore, regulating ChREBP activity could be an attractive target for lipid-lowering therapies in obesity and diabetes. However, before this is possible, a better understanding of the mechanism(s) regulating its activity is needed. In this review, we summarize recent findings on the role and regulation of ChREBP and particularly emphasize on the cross-regulations that may exist between key nuclear receptors (LXR, TR, HNF4α) and ChREBP for the control of hepatic glucose metabolism. These novel molecular cross-talks may open the way to new pharmacological opportunities. This article is part of a Special Issue entitled: Translating nuclear receptors from health to disease.
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72
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Pepper MP, Vatamaniuk MZ, Yan X, Roneker CA, Lei XG. Impacts of dietary selenium deficiency on metabolic phenotypes of diet-restricted GPX1-overexpressing mice. Antioxid Redox Signal 2011; 14:383-90. [PMID: 20578960 PMCID: PMC3026648 DOI: 10.1089/ars.2010.3295] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We previously reported a spontaneous development of type 2 diabetes-like phenotypes in glutathione peroxidase-1 (GPX1)-overexpressing (OE) mice. Diet restriction of these mice rescued all their phenotypes, except for hyperinsulinemia and hypersecretion of insulin. This study was to determine whether dietary Se deficiency eliminated these two primary effects of GPX1 overproduction. Forty-seven male OE and wild-type (WT) mice were fed an Se-adequate (0.4 mg Se/kg) or deficient (<0.02 mg Se/kg) diet at 2 to 3 g (full-fed = 5 g) per day from 4 to 12 weeks of age. Although dietary Se deficiency did not rescue the primary phenotypes of the diet-restricted OE mice, it exerted a strong effect (p < 0.05) on mRNA or protein levels (or both) of 14 molecules involved in islet insulin synthesis and secretion and hepatic lipogenesis. Dietary Se deficiency exhibited a hypoinsulinemic trend in OE mice and a strong hypolipidemic effect (p < 0.05) in the liver of WT mice. Hepatic lipogenesis was attenuated in OE compared with WT mice. In conclusion, diet restriction might be too overwhelming to allow a demonstration of a dietary Se-depletion effect on the OE phenotypes. Full-fed animals could offer a better chance to illustrate such effects and the underlying mechanisms.
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Affiliation(s)
- Matthew P Pepper
- Department of Animal Science, Cornell University, Ithaca, New York 14853, USA
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73
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Kim SK, Kong CS. Anti-adipogenic effect of dioxinodehydroeckol via AMPK activation in 3T3-L1 adipocytes. Chem Biol Interact 2010; 186:24-9. [PMID: 20385110 DOI: 10.1016/j.cbi.2010.04.003] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Revised: 03/30/2010] [Accepted: 04/02/2010] [Indexed: 11/16/2022]
Abstract
Dioxinodehydroeckol (DHE) isolated from Ecklonia cava, has previously been investigated for its inhibition of the differentiation of 3T3-L1 preadipocytes into adipocytes. Levels of lipid accumulation were measured, along with changes in the expression of genes and proteins associated with adipogenesis and lipolysis. Confluent 3T3-L1 preadipocytes in medium with or without different concentrations of DHE for 7 days were differentiated into adipocytes. Lipid accumulation was quantified by measuring direct triglyceride contents and Oil-Red O staining. The expression of genes and proteins associated with adipogenesis and lipolysis was measured using RT-PCR, quantitative real-time RT-PCR and Western blotting analysis. It was found that the presence of DHE significantly reduced lipid accumulation and down-regulated the expression of peroxisome proliferator-activated receptor-gamma (PPARgamma), sterol regulatory element-binding protein 1 (SREBP1) and CCAAT/enhancer-binding proteins (C/EBPalpha) in a dose-dependent manner. Moreover, DHE suppressed regulation of the adipocyte-specific gene promoters such as fatty acid binding protein (FABP4), fatty acid transport protein (FATP1), fatty acid synthase (FAS), lipoprotein lipase (LPL), acyl-CoA synthetase 1 (ACS1), leptin, perilipin and HSL compared to control adipocytes. The specific mechanism mediating the effects of DHE was confirmed by activation of phosphorylated AMP-activated protein kinase (pAMPK). Therefore, these results suggest that DHE exerts anti-adipogenic effect on adipocyte differentiation through the activation and modulation of the AMPK signaling pathway.
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Affiliation(s)
- Se-Kwon Kim
- Marine Bioprocess Research Center, Pukyong National University, Busan, Republic of Korea.
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74
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Kong CS, Kim JA, Ahn BN, Vo TS, Yoon NY, Kim SK. 1-(3',5'-dihydroxyphenoxy)-7-(2'',4'',6-trihydroxyphenoxy)-2,4,9-trihydroxydibenzo-1,4-dioxin inhibits adipocyte differentiation of 3T3-L1 fibroblasts. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2010; 12:299-307. [PMID: 19680725 DOI: 10.1007/s10126-009-9224-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Accepted: 07/14/2009] [Indexed: 05/28/2023]
Abstract
In this study, we isolated the phloroglucinol derivative, 1-(3',5'-dihydroxyphenoxy)-7-(2'',4'',6-trihydroxyphenoxy)-2,4,9-trihydroxydibenzo-1,4-dioxin (1), from Ecklonia cava and evaluated its potential inhibition on adipocyte differentiation in 3T3-L1 cells. Lipid accumulation along with the expression of several genes associated with adipogenesis and lipolysis was examined at the end of differentiation. Lipid accumulation level was examined by measuring triglyceride content and Oil-Red O staining. The expression levels of several genes and proteins were examined using reverse-transcription polymerase chain reaction (RT-PCR), real-time RT-PCR, and Western blot analysis. Compound 1 significantly reduced lipid accumulation and downregulated peroxisome proliferator-activated receptor-gamma, sterol regulatory element-binding protein 1c, and CCAAT/enhancer-binding proteins alpha in a dose-dependent manner. Moreover, the presence of compound 1 induced downregulation of adipogenic target genes such as fatty acid binding protein 4, fatty acid transport protein 1, fatty acid synthase, acyl-CoA synthetase 1, lipoprotein lipase, and leptin. According to the lipolytic response, compound 1 downregulated perilipin and hormone-sensitive lipase while upregulating tumor necrosis factor alpha. Therefore, these results suggest that compound 1 might decrease lipid accumulation during adipocyte differentiation by modulating adipogenesis and lipogenesis. Furthermore, compound 1 could be developed as a functional agent effective in improving obesity.
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Affiliation(s)
- Chang-Suk Kong
- Marine Bioprocess Research Center, Pukyong National University, Busan, 608-737, South Korea
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75
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Jackel-Cram C, Qiao L, Xiang Z, Brownlie R, Zhou Y, Babiuk L, Liu Q. Hepatitis C virus genotype-3a core protein enhances sterol regulatory element-binding protein-1 activity through the phosphoinositide 3-kinase-Akt-2 pathway. J Gen Virol 2010; 91:1388-95. [PMID: 20130133 DOI: 10.1099/vir.0.017418-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Hepatitis C virus genotype-3a (HCV-3a) is directly linked to the development of steatosis. We previously showed that, through sterol regulatory element binding protein-1 (SREBP-1), HCV-3a core protein upregulates the promoter activity of fatty acid synthase, a major enzyme involved in de novo lipid synthesis. In this study, we investigated whether HCV-3a core can activate SREBP-1 and studied the role of phosphoinositide 3-kinase (PI3K)-Akt-2 pathway in modulating SREBP-1 activity by HCV-3a core. To determine whether HCV-3a core could activate SREBP-1, the level of mature SREBP-1 was analysed by Western blotting. Our results showed that the level of mature SREBP-1 was enhanced by HCV-3a core protein after transient expression and in the chimeric HCV-3a core/1b replicon cells in comparison to controls. To investigate the role of the PI3K-Akt-2 pathway in SREBP-1 activation by HCV-3a core, PI3K and Akt-2 activity was inhibited by using the chemical inhibitor LY294002, a dominant-negative Akt-2 plasmid, or knockdown of Akt-2 by small hairpin RNA. Our results showed that inhibition of PI3K and Akt-2 was associated with reduced SREBP-1 activation by HCV-3a core. These results indicate a role for PI3K and Akt-2 in increasing SREBP-1 activity by HCV-3a core protein and provide a mechanism of steatosis caused by HCV.
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Affiliation(s)
- Candice Jackel-Cram
- Vaccine and Infectious Disease Organization, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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76
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Hong JH, Hwang EY, Kim HJ, Jeong YJ, Lee IS. Artemisia capillaris inhibits lipid accumulation in 3T3-L1 adipocytes and obesity in C57BL/6J mice fed a high fat diet. J Med Food 2009; 12:736-45. [PMID: 19735172 DOI: 10.1089/jmf.2008.1240] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The purpose of the current study was to determine the effect of the Artemisia capillaris ethyl acetate (ACE) fraction on diet-induced obesity and to elucidate the underlying mechanism. The ACE fraction treatment decreased the leptin level and fat accumulation in cultured 3T3-L1 adipocytes through the free fatty acids released in the medium. The ACE fraction significantly suppressed the expression of peroxisome proliferator-activated receptor-gamma in cultured 3T3-L1 adipocytes. To determine the effect of the ACE fraction on C57BL/6J male mice, the mice were separated into six groups: normal control (N), N plus 0.1 g/kg body weight ACE (NB), high fat control group (HF), HF plus 0.05 g/kg of body weight ACE (HFA), HF plus 0.1 g/kg of body weight ACE (HFB), and HF plus 0.03 g/kg of body weight rosiglitazone (RG) groups. We speculate that the HFB group exhibits a lipid-lowering effect via increased mitochondrial beta-oxidation, of which the rate-limiting enzyme is carnitine palmitoyl transferase I, the activity of which was significantly increased. Also, the activity of fatty acid synthase, a key enzyme of fatty acid synthesis, was markedly suppressed (19%) in the HFB group, as compared to the HF group, and glycerol-3-phosphate dehydrogenase activity, which is very useful in studying adipogenic differentiation in vitro, was markedly suppressed (30%) in the HFB group compared with the HF group. Furthermore, the HFB group showed lowered hepatic lipid droplet accumulation and adipose tissue weight and size. We suggest that 0.1 g of the ACE fraction/kg of body weight may exert an anti-obesity effect in C57BL/6J mice by enhancing lipid metabolism.
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Affiliation(s)
- Jung-Hee Hong
- The Center for Traditional Microorganism Resources Center, Keimyung University, Daegu, Republic of Korea
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77
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Anti-obesity effect of sulfated glucosamine by AMPK signal pathway in 3T3-L1 adipocytes. Food Chem Toxicol 2009; 47:2401-6. [DOI: 10.1016/j.fct.2009.06.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2009] [Revised: 05/14/2009] [Accepted: 06/04/2009] [Indexed: 11/18/2022]
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78
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Wong RHF, Sul HS. DNA-PK: relaying the insulin signal to USF in lipogenesis. Cell Cycle 2009; 8:1977-8. [PMID: 19550139 DOI: 10.4161/cc.8.13.8941] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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79
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Kong CS, Kim JA, Eom TK, Kim SK. Phosphorylated glucosamine inhibits adipogenesis in 3T3-L1 adipocytes. J Nutr Biochem 2009; 21:438-43. [PMID: 19427183 DOI: 10.1016/j.jnutbio.2009.01.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Revised: 01/19/2009] [Accepted: 01/28/2009] [Indexed: 12/20/2022]
Abstract
Phosphorylated glucosamine (glucosamine-6-phosphate, PGlc) was synthesized using methanesulfonic acid, phosphorus pentoxide (P(2)O(5)), NH(2)NH(2) and DMF. Its inhibitory effect on lipid accumulation in cultured 3T3-L1 adipocytes was investigated by measuring triglyceride contents and Oil Red O staining. In order to understand the mechanism by which lipid accumulation in adipocytes is decreased by PGlc, we examined the expression levels of several genes and proteins associated with adipogenesis and lipolysis using reverse transcription polymerase chain reaction, real-time polymerase chain reaction and Western blot analysis. Treatment with PGlc significantly reduced lipid accumulation during adipocyte differentiation and induced down-regulation of peroxisome proliferator-activated receptor-gamma, sterol regulatory element binding protein 1 and CCAAT/enhancer binding protein-alpha in a dose-dependent manner. Moreover, treatment with PGlc during adipocyte differentiation induced significant up-regulation of preadipocyte factor 1 mRNA and down-regulation of such adipocyte-specific gene promoters as adipocyte fatty acid binding protein, fatty acid synthase, lipoprotein lipase and leptin. According to the lipolytic response, PGlc up-regulated hormone-sensitive lipase mRNA expression and suppressed the expression levels of tumor necrosis factor-alpha mRNA compared with fully differentiated adipose tissue. These results suggest that the inhibitory effect of PGlc on adipocyte differentiation might be mediated through the down-regulation of adipogenic transcription factors, such as peroxisome proliferator-activated receptor-gamma, sterol regulatory element binding protein 1 and CCAAT/enhancer binding protein-alpha, which are related to the downstream adipocyte-specific gene promoters.
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Affiliation(s)
- Chang-Suk Kong
- Marine Bioprocess Research Center, Pukyong National University, Busan, South Korea
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80
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Wong RHF, Chang I, Hudak CSS, Hyun S, Kwan HY, Sul HS. A role of DNA-PK for the metabolic gene regulation in response to insulin. Cell 2009; 136:1056-72. [PMID: 19303849 DOI: 10.1016/j.cell.2008.12.040] [Citation(s) in RCA: 201] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Revised: 07/25/2008] [Accepted: 12/19/2008] [Indexed: 10/21/2022]
Abstract
Fatty acid synthase (FAS) is a central enzyme in lipogenesis and transcriptionally activated in response to feeding and insulin signaling. The transcription factor USF is required for the activation of FAS transcription, and we show here that USF phosphorylation by DNA-PK, which is dephosphorylated by PP1 in response to feeding, triggers a switch-like mechanism. Under fasting conditions, USF-1 is deacetylated by HDAC9, causing promoter inactivation. In contrast, feeding induces the recruitment of DNA-PK to USF-1 and its phosphorylation, which then allows recruitment of P/CAF, resulting in USF-1 acetylation and FAS promoter activation. DNA break/repair components associated with USF induce transient DNA breaks during FAS activation. In DNA-PK-deficient SCID mice, feeding-induced USF-1 phosphorylation/acetylation, DNA breaks, and FAS activation leading to lipogenesis are impaired, resulting in decreased triglyceride levels. Our study demonstrates that a kinase central to the DNA damage response mediates metabolic gene activation.
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Affiliation(s)
- Roger H F Wong
- Department of Nutritional Science and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA
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81
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Functional analysis of rat liver citrate carrier promoter: differential responsiveness to polyunsaturated fatty acids. Biochem J 2009; 417:561-71. [PMID: 18795892 DOI: 10.1042/bj20081082] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
CiC (citrate carrier), a mitochondrial membrane protein, plays an important metabolic role by transporting acetyl-CoA into the cytosol for fatty acid and cholesterol synthesis. Several studies showed that CiC activity and expression is regulated by dietary fatty acids. In the present study we report data on the structural and functional characterization of the 5'-flanking region of the rat Cic gene. By transient transfection assays in H4IIE rat hepatoma cells, a PUFA (polyunsaturated fatty acids) response region has been identified within the CiC promoter. A cluster of putative binding sites for several transcription factors, composed of a NF-Y (nuclear factor-Y) site, an E-box-like site, a SRE1 (sterol regulatory element 1)-like site and four Sp1 (stimulatory protein 1) sites, was localized in the promoter region. Luciferase reporter gene and gel mobility shift assays indicated that a functional E-box-like, essential to the basal CiC promoter activity, confers responsiveness to activation by SREBP (SRE-binding protein)-1c. This study provides evidence for SREBP-1c as a principal target for PUFA regulation of CiC transcription. In H4IIE cells, overexpression of nSREBP (nuclear SREBP)-1c over-rides arachidonic acid (C(20:4, n-6)) suppression, but does not prevent the repression by docosahexaenoic acid (C(22:6, n-3)). ChIP (chromatin immunoprecipitation) assays in H4IIE cells showed that docosahexaenoic acid affects the binding of NF-Y, Sp1 and SREBP-1 to the PUFA response region of CiC promoter, whereas arachidonic acid alters only the binding of SREBP-1. Our data show that PUFA inhibition of hepatic Cic gene transcription is mediated not only by the nuclear level of SREBP-1c, but also might involve a reduction in Sp1 and NF-Y DNA binding, suggesting differential mechanisms in the Cic gene regulation by different PUFA.
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82
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Zou Y, Du H, Yin M, Zhang L, Mao L, Xiao N, Ren G, Zhang C, Pan J. Effects of high dietary fat and cholesterol on expression of PPAR alpha, LXR alpha, and their responsive genes in the liver of apoE and LDLR double deficient mice. Mol Cell Biochem 2008; 323:195-205. [PMID: 19067122 DOI: 10.1007/s11010-008-9982-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Accepted: 11/28/2008] [Indexed: 11/28/2022]
Abstract
The significance of transcription factors PPAR alpha, LXR alpha, and their responsive/target genes for the pathogenesis of atherosclerosis in apolipoprotein E and low-density lipoprotein receptor double deficient (AL) mice fed with high fat and cholesterol (HF) diet were studied. C57BL/6J wild-type (WT) mice were used as control to the AL mice. Plasma lipid metabolites and morphological atherosclerotic lesions in aortic wall were determined. Semi- and real-time quantitative RT-PCR were used to measure gene expression patterns between AL mice and the controls, which were fed with HF or normal chow diet. The results showed that in AL mice fed with HF diet, plasma lipid levels, hepatic lipid accumulation, and atherogenesis together with upregulated PPAR alpha, LXR alpha, and their target genes, i.e., FAT, SCD1, FAS, Angptl3, and apoB100 significantly increased in a 12-week long feeding period. In contrast, apoAI, apoAIV, apoF, LPL, and SR-BI were decreased compared to chow-fed group. In WT mice, PPAR alpha, LXR alpha, FAS, Angpt13, CPT1, apoF, ACOX1, LPL, and SR-BI were increased with HF treatment, while apoAI and apoAIV were decreased markedly. The different changes of lipid metabolism-related genes between AL and WT mice, fed with HF diet or chow diet indicated that the mechanisms of dietary effects on gene mutant mice are different from those of intact WT mice. Since lipid metabolic system defected genetically in AL mice, we suggest that the changes of PPAR alpha, LXR alpha, and their target genes aggravated lipid metabolic disorder in the liver and further accelerated the development of atherosclerosis on a stress of HF diet feeding in AL mice.
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Affiliation(s)
- Yanyan Zou
- The Key Laboratory of Animal Resistant Biology of Shandong, College of Life Sciences, Shandong Normal University, Jinan, 250014, People's Republic of China
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83
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Choi WI, Jeon BN, Park H, Yoo JY, Kim YS, Koh DI, Kim MH, Kim YR, Lee CE, Kim KS, Osborne TF, Hur MW. Proto-oncogene FBI-1 (Pokemon) and SREBP-1 synergistically activate transcription of fatty-acid synthase gene (FASN). J Biol Chem 2008; 283:29341-54. [PMID: 18682402 PMCID: PMC2662021 DOI: 10.1074/jbc.m802477200] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2008] [Revised: 07/28/2008] [Indexed: 01/25/2023] Open
Abstract
FBI-1 (Pokemon/ZBTB7A) is a proto-oncogenic transcription factor of the BTB/POZ (bric-à-brac, tramtrack, and broad complex and pox virus zinc finger) domain family. Recent evidence suggested that FBI-1 might be involved in adipogenic gene expression. Coincidentally, expression of FBI-1 and fatty-acid synthase (FASN) genes are often increased in cancer and immortalized cells. Both FBI-1 and FASN are important in cancer cell proliferation. SREBP-1 is a major regulator of many adipogenic genes, and FBI-1 and SREBP-1 (sterol-responsive element (SRE)-binding protein 1) interact with each other directly via their DNA binding domains. FBI-1 enhanced the transcriptional activation of SREBP-1 on responsive promoters, pGL2-6x(SRE)-Luc and FASN gene. FBI-1 and SREBP-1 synergistically activate transcription of the FASN gene by acting on the proximal GC-box and SRE/E-box. FBI-1, Sp1, and SREBP-1 can bind to all three SRE, GC-box, and SRE/E-box. Binding competition among the three transcription factors on the GC-box and SRE/E-box appears important in the transcription regulation. FBI-1 is apparently changing the binding pattern of Sp1 and SREBP-1 on the two elements in the presence of induced SREBP-1 and drives more Sp1 binding to the proximal promoter with less of an effect on SREBP-1 binding. The changes induced by FBI-1 appear critical in the synergistic transcription activation. The molecular mechanism revealed provides insight into how proto-oncogene FBI-1 may attack the cellular regulatory mechanism of FASN gene expression to provide more phospholipid membrane components needed for rapid cancer cell proliferation.
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Affiliation(s)
- Won-Il Choi
- Department of Biochemistry and Molecular Biology, Brain Korea 21 Project for Medical Science, Institute of Genetic Science, Yonsei University School of Medicine, 134, ShinChon-Dong, SeoDaeMoon-Ku, Seoul 120-752, Korea
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84
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Oem JK, Jackel-Cram C, Li YP, Zhou Y, Zhong J, Shimano H, Babiuk LA, Liu Q. Activation of sterol regulatory element-binding protein 1c and fatty acid synthase transcription by hepatitis C virus non-structural protein 2. J Gen Virol 2008; 89:1225-1230. [PMID: 18420801 DOI: 10.1099/vir.0.83491-0] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Transcriptional factor sterol regulatory element-binding protein 1c (SREBP-1c) activates the transcription of lipogenic genes, including fatty acid synthase (FAS). Hepatitis C virus (HCV) infection is often associated with lipid accumulation within the liver, known as steatosis in the clinic. The molecular mechanisms of HCV-associated steatosis are not well characterized. Here, we showed that HCV non-structural protein 2 (NS2) activated SREBP-1c transcription in human hepatic Huh-7 cells as measured by using a human SREBP-1c promoter-luciferase reporter plasmid. We further showed that sterol regulatory element (SRE) and liver X receptor element (LXRE) in the SREBP-1c promoter were involved in SREBP-1c activation by HCV NS2. Furthermore, expression of HCV NS2 resulted in the upregulation of FAS transcription. We also showed that FAS upregulation by HCV NS2 was SREBP-1-dependent since deleting the SRE sequence in a FAS promoter and expressing a dominant-negative SREBP-1 abrogated FAS promoter upregulation by HCV NS2. Taken together, our results suggest that HCV NS2 can upregulate the transcription of SREBP-1c and FAS, and thus is probably a contributing factor for HCV-associated steatosis.
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Affiliation(s)
- Jae-Ku Oem
- Vaccine and Infectious Disease Organization (VIDO), University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E3, Canada
| | - Candice Jackel-Cram
- Vaccine and Infectious Disease Organization (VIDO), University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E3, Canada
| | - Yi-Ping Li
- Vaccine and Infectious Disease Organization (VIDO), University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E3, Canada
| | - Yan Zhou
- Vaccine and Infectious Disease Organization (VIDO), University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E3, Canada
| | - Jin Zhong
- Institut Pasteur of Shanghai, Shanghai, PR China
| | | | - Lorne A Babiuk
- University of Alberta, Edmonton, Alberta, Canada.,Vaccine and Infectious Disease Organization (VIDO), University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E3, Canada
| | - Qiang Liu
- Vaccine and Infectious Disease Organization (VIDO), University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E3, Canada
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85
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Retinoic acid-mediated transcription and maturation of SREBP-1c regulates fatty acid synthase via cis-elements responsible for nutritional regulation. Biochem Soc Trans 2008; 35:1211-4. [PMID: 17956315 DOI: 10.1042/bst0351211] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A region of the rat FAS (fatty acid synthase) promoter has been defined as being responsible for RA (retinoic acid) responsiveness. The defined promoter region is devoid of canonical RA-response elements but contains cis-elements binding generalized and specific transcription factors that mediate the dietary response of FAS. Our results are consistent with SREBP-1c (sterol-regulatory-element-binding protein 1c) binding in this region, thus bringing about the RA responsiveness of the rat FAS proximal promoter.
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86
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Tiwari R, Singh V, Barthwal M. Macrophages: An elusive yet emerging therapeutic target of atherosclerosis. Med Res Rev 2008; 28:483-544. [DOI: 10.1002/med.20118] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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87
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88
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Roder K, Zhang L, Schweizer M. SREBP-1c mediates the retinoid-dependent increase in fatty acid synthase promoter activity in HepG2. FEBS Lett 2007; 581:2715-20. [PMID: 17531980 DOI: 10.1016/j.febslet.2007.05.022] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Revised: 04/27/2007] [Accepted: 05/09/2007] [Indexed: 01/28/2023]
Abstract
Treatment of HepG2 with all-trans retinoic acid (RA) induces expression of fatty acid synthase (FAS) mRNA and protein. Transfections show that the FAS promoter positively responds to retinoid X receptor (RXR) but not to RA receptor (RAR) agonists. Since RXR alone is capable of mediating the RA response of FAS, the existence of a classical RA-responsive element in the FAS promoter may be ruled out. Binding sites for NF-Y and SREBP-1 proved to be essential for the RA response. Exposure to all-trans RA increased mRNA and protein levels of SREBP-1, a transcriptional activator for FAS. Overexpression of a dominant-negative form of SREBP-1c diminished the RA-dependent increase in promoter activity. These data demonstrate that RXR ligands can stimulate the expression of a lipogenic gene solely by inducing transcription and cleavage of membrane-bound SREBP-1c.
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Affiliation(s)
- Karim Roder
- School of Life Sciences, Heriot-Watt University, Edinburgh, UK
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89
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Sekiya M, Yahagi N, Matsuzaka T, Takeuchi Y, Nakagawa Y, Takahashi H, Okazaki H, Iizuka Y, Ohashi K, Gotoda T, Ishibashi S, Nagai R, Yamazaki T, Kadowaki T, Yamada N, Osuga JI, Shimano H. SREBP-1-independent regulation of lipogenic gene expression in adipocytes. J Lipid Res 2007; 48:1581-91. [PMID: 17456898 DOI: 10.1194/jlr.m700033-jlr200] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Sterol regulatory element-binding protein (SREBP)-1c is now well established as a key transcription factor for the regulation of lipogenic enzyme genes such as FAS in hepatocytes. Meanwhile, the mechanisms of lipogenic gene regulation in adipocytes remain unclear. Here, we demonstrate that those in adipocytes are independent of SREBP-1c. In adipocytes, unlike in hepatocytes, the stimulation of SREBP-1c expression by liver X receptor agonist does not accompany lipogenic gene upregulation, although nuclear SREBP-1c protein is concomitantly increased, indicating that the activation process of SREBP-1c by the cleavage system is intact in adipocytes. Supportively, transcriptional activity of the mature form of SREBP-1c for the FAS promoter was negligible when measured by reporter analysis. As an underlying mechanism, accessibility of SREBP-1c to the functional elements was involved, because chromatin immunoprecipitation assays revealed that SREBP-1c does not bind to the functional SRE/E-box site on the FAS promoter in adipocytes. Moreover, genetic disruption of SREBP-1 did not cause any changes in lipogenic gene expression in adipose tissue. In summary, in adipocytes, unlike in hepatocytes, increments in nuclear SREBP-1c are not accompanied by transactivation of lipogenic genes; thus, SREBP-1c is not committed to the regulation of lipogenesis.
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Affiliation(s)
- Motohiro Sekiya
- Department of Internal Medicine, Graduate School of Medicine, University of Tokyo, Tokyo 113-8655, Japan
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90
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Teran-Garcia M, Adamson A, Yu G, Rufo C, Suchankova G, Dreesen T, Tekle M, Clarke S, Gettys T. Polyunsaturated fatty acid suppression of fatty acid synthase (FASN): evidence for dietary modulation of NF-Y binding to the Fasn promoter by SREBP-1c. Biochem J 2007; 402:591-600. [PMID: 17313375 PMCID: PMC1863568 DOI: 10.1042/bj20061722] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Dietary PUFAs (polyunsaturated fatty acids) co-ordinately suppress transcription of a group of hepatic genes encoding glycolytic and lipogenic enzymes. Suppression of Fasn (fatty acid synthase) transcription involves two PUFA-responsive regions, but the majority of PUFA sensitivity maps to a region within the proximal promoter containing binding sites for NF-Y (nuclear factor-Y), Sp1 (stimulatory protein 1), SREBP (sterol-regulatory-elementbinding protein), and USF (upstream stimulatory factor). Promoter activation assays indicate that altered NF-Y is the key component in regulation of Fasn promoter activity by PUFA. Using electrophoretic mobility-shift assay and chromatin immunoprecipitation analysis, we demonstrate for the first time that PUFAs decrease in vivo binding of NF-Y and SREBP-1c to the proximal promoter of the hepatic Fasn gene and the promoters of three additional genes, spot 14, stearoyl-CoA desaturase and farnesyl diphosphate synthase that are also down-regulated by PUFA. The comparable 50% decrease in NF-Y and SREBP-1c binding to the promoters of the respective PUFA-sensitive genes occurred despite no change in nuclear NF-Y content and a 4-fold decrease in SREBP-1c. Together, these findings support a mechanism whereby PUFA reciprocally regulates the binding of NF-Y and SREBP-1c to a subset of genes which share similar contiguous arrangements of sterol regulatory elements and NF-Y response elements within their promoters. PUFA-dependent regulation of SREBP-1c and NF-Y binding to this unique configuration of response elements may represent a nutrient-sensitive motif through which PUFA selectively and co-ordinately targets subsets of hepatic genes involved in lipid metabolism.
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Affiliation(s)
- Margarita Teran-Garcia
- *Department of Adipocyte Signalling, Pennington Biomedical Research Center, Baton Rouge, LA 70808, U.S.A
| | - Aaron W. Adamson
- *Department of Adipocyte Signalling, Pennington Biomedical Research Center, Baton Rouge, LA 70808, U.S.A
| | - Gang Yu
- *Department of Adipocyte Signalling, Pennington Biomedical Research Center, Baton Rouge, LA 70808, U.S.A
| | - Caterina Rufo
- †Catedra de Inmunologia, Facultad de Quimica, Universidad de la Republica, Instituto de Higiene, Montevideo, Uruguay
| | | | | | - Michael Tekle
- *Department of Adipocyte Signalling, Pennington Biomedical Research Center, Baton Rouge, LA 70808, U.S.A
| | | | - Thomas W. Gettys
- *Department of Adipocyte Signalling, Pennington Biomedical Research Center, Baton Rouge, LA 70808, U.S.A
- To whom correspondence should be addressed (email )
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91
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Beyea MM, Heslop CL, Sawyez CG, Edwards JY, Markle JG, Hegele RA, Huff MW. Selective Up-regulation of LXR-regulated Genes ABCA1, ABCG1, and APOE in Macrophages through Increased Endogenous Synthesis of 24(S),25-Epoxycholesterol. J Biol Chem 2007; 282:5207-16. [PMID: 17186944 DOI: 10.1074/jbc.m611063200] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Liver X receptor (LXR) activation represents a mechanism to prevent macrophage foam cell formation. Previously, we demonstrated that partial inhibition of oxidosqualene:lanosterol cyclase (OSC) stimulated synthesis of the LXR agonist 24(S),25-epoxycholesterol (24(S),25-epoxy) and enhanced ABCA1-mediated cholesterol efflux. In contrast to a synthetic, nonsteroidal LXR activator, TO-901317, triglyceride accumulation was not observed. In the present study, we determined whether endogenous 24(S),25-epoxy synthesis selectively enhanced expression of macrophage LXR-regulated cholesterol efflux genes but not genes that regulate fatty acid metabolism. THP-1 human macrophages incubated with the OSC inhibitor (OSCi) RO0714565 (15 nM) significantly reduced cholesterol synthesis and maximized synthesis of 24(S),25-epoxy. Endogenous 24(S),25-epoxy increased ABCA1, ABCG1, and APOE mRNA abundance and consequently increased cholesterol efflux to apoAI. In contrast, OSCi had no effect on LXR-regulated genes LPL (lipoprotein lipase) and FAS (fatty acid synthase). TO-901317 (>or=10 nM) significantly enhanced expression of all genes examined. OSCi and TO-901317 increased the mRNA and precursor form of SREBP-1c, a major regulator of fatty acid and triglyceride synthesis. However, conversion of the precursor to the active form (nSREBP-1c) was blocked by OSCi-induced 24(S),25-epoxy but not by TO-901317 (>or=10 nm), which instead markedly increased nSREBP-1c. Disruption of nSREBP-1c formation by 24(S),25-epoxy accounted for diminished FAS and LPL expression. In summary, endogenous synthesis of 24(S),25-epoxy selectively up-regulates expression of macrophage LXR-regulated cholesterol efflux genes without stimulating genes linked to fatty acid and triglyceride synthesis.
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Affiliation(s)
- Michael M Beyea
- Robarts Research Institute Vascular Biology Group, Department of Biochemistry, University of Western, London, Ontario, Canada
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92
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Griffin MJ, Wong RHF, Pandya N, Sul HS. Direct interaction between USF and SREBP-1c mediates synergistic activation of the fatty-acid synthase promoter. J Biol Chem 2006; 282:5453-67. [PMID: 17197698 DOI: 10.1074/jbc.m610566200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
To understand the molecular mechanisms underlying transcriptional activation of fatty-acid synthase (FAS), we examined the relationship between upstream stimulatory factor (USF) and SREBP-1c, two transcription factors that we have shown previously to be critical for FAS induction by feeding/insulin. Here, by using a combination of tandem affinity purification and coimmunoprecipitation, we demonstrate, for the first time, that USF and SREBP-1 interact in vitro and in vivo. Glutathione S-transferase pulldown experiments with various USF and sterol regulatory element-binding protein (SREBP) deletion constructs indicate that the basic helix-loop-helix domain of USF interacts directly with the basic helix-loop-helix and an N-terminal region of SREBP-1c. Furthermore, cotransfection of USF and SREBP-1c with an FAS promoter-luciferase reporter construct in Drosophila SL2 cells results in highly synergistic activation of the FAS promoter. We also show similar cooperative activation of the mitochondrial glycerol-3-phosphate acyltransferase promoter by USF and SREBP-1c. Chromatin immunoprecipitation analysis of mouse liver demonstrates that USF binds constitutively to the mitochondrial glycerol 3-phosphate acyltransferase promoter during fasting/refeeding in vivo, whereas binding of SREBP-1 is observed only during refeeding, in a manner identical to that of the FAS promoter. In addition, we show that the synergy we have observed depends on the activation domains of both proteins and that mutated USF or SREBP lacking the N-terminal activation domain could inhibit the transactivation of the other. Closely positioned E-boxes and sterol regulatory elements found in the promoters of several lipogenic genes suggest a common mechanism of induction by feeding/insulin.
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Affiliation(s)
- Michael J Griffin
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, California 94720, USA
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93
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Zhang YL, Hernandez-Ono A, Siri P, Weisberg S, Conlon D, Graham MJ, Crooke RM, Huang LS, Ginsberg HN. Aberrant hepatic expression of PPARgamma2 stimulates hepatic lipogenesis in a mouse model of obesity, insulin resistance, dyslipidemia, and hepatic steatosis. J Biol Chem 2006; 281:37603-15. [PMID: 16971390 DOI: 10.1074/jbc.m604709200] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin-resistant apoB/BATless mice have hypertriglyceridemia because of increased assembly and secretion of very low density apolipoprotein B (apoB) and triglycerides compared with mice expressing only apoB (Siri, P., Candela, N., Ko, C., Zhang, Y., Eusufzai, S., Ginsberg, H. N., and Huang, L. S. (2001) J. Biol. Chem. 276, 46064-46072). Despite increased very low density lipoprotein secretion, apoB/BATless mice have fatty livers. We found that hepatic mRNA levels of key lipogenic enzymes, acetyl-CoA carboxylase, fatty-acid synthase, and stearoyl-CoA desaturase-1 were increased in apoB/BATless mice compared with levels in apoB mice, suggesting increased lipogenesis in apoB/BATless mice. This was confirmed by determining incorporation of tritiated water into fatty acids. Neither the hepatic mRNA of the lipogenic transcription factor, SREBP-1c (sterol-response element-binding protein 1c), nor the nuclear levels of the mature form of SREBP-1 protein were elevated in apoB/BATless mice. By contrast, hepatic levels of peroxisomal proliferator-activated receptor 2 (PPARgamma2) mRNA and protein were specifically increased in apoB/BATless mice, as were hepatic mRNA levels of two targets of PPARgamma, CD36 and aP2. Treatment of apoB/BATless mice for 4 weeks with intraperitoneal injections of a PPARgamma antisense oligonucleotide resulted in dramatic reductions of both PPARgamma1 and PPARgamma2 mRNA, PPARgamma2 protein, and mRNA levels of fatty-acid synthase and acetyl-CoA carboxylase. These changes were associated with decreased hepatic de novo lipogenesis and hepatic triglyceride concentrations. We conclude that hepatic steatosis in apoB/BATless mice is associated with elevated rates of hepatic lipogenesis that are linked directly to increased hepatic expression of PPARgamma2. The mechanism whereby hepatic Ppargamma2 gene expression is increased and how PPARgamma2 stimulates lipogenesis is under investigation.
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Affiliation(s)
- Yuan-Li Zhang
- Department of Medicine, College of Physicians and Surgeons of Columbia University, New York, New York 10032, USA
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94
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Chang Y, Edeen K, Lu X, De Leon M, Mason RJ. Keratinocyte growth factor induces lipogenesis in alveolar type II cells through a sterol regulatory element binding protein-1c-dependent pathway. Am J Respir Cell Mol Biol 2006; 35:268-74. [PMID: 16601238 PMCID: PMC2643261 DOI: 10.1165/rcmb.2006-0037oc] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Keratinocyte growth factor (KGF) stimulates fatty acid and phospholipid synthesis in alveolar type II cells in vitro. KGF stimulates lipogenic enzymes, including fatty acid synthase and stearyl-CoA desaturase-1, and transcription factors involved in lipogenesis, such as sterol regulatory element binding protein (SREBP)-1c and CCAAT/enhancer binding protein (C/EBP)alpha and C/EBPdelta. To define the role of SREBP-1c on the induction of lipogenic genes and lipogenesis by KGF in primary cultures of rat type II cells, we used adenoviral vectors to alter levels of SREBP-1c. Overexpression of a dominant-negative form of SREBP-1 decreased lipogenesis and decreased the induction of fatty acid synthase and stearyl coenzyme A desaturase-1 by KGF. Conversely, adenovirus-mediated overexpression of a constitutively active form of SREBP-1c mimicked the effect of KGF on lipogenic enzymes and lipogenesis. These data indicate that SREBP-1c is required for the stimulation of lipogenesis by KGF in the alveolar type II cells and is a key regulator of lung lipid metabolism and that expression of SREBP-1c is sufficient to induce lipogenesis in rat type II cells.
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Affiliation(s)
- Yongsheng Chang
- National Jewish Medical and Research Center, 1400 Jackson Street, Denver, CO 80206, USA
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95
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Ahn IS, Do MS, Kim SO, Jung HS, Kim YI, Kim HJ, Park KY. Antiobesity Effect ofKochujang(Korean Fermented Red Pepper Paste) Extract in 3T3-L1 Adipocytes. J Med Food 2006; 9:15-21. [PMID: 16579723 DOI: 10.1089/jmf.2006.9.15] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Kochujang (Korean fermented red pepper paste) is a mixture of fermented soybeans, wheat, and red pepper powder. Kochujang has been reported to reduce body fat gain and lipid levels of adipose tissues and serum in rats. We studied the inhibitory effect of Kochujang on lipid accumulation and investigated the molecular mechanism of the action in 3T3-L1 adipocytes by measuring the expression levels of adipocyte-specific genes by real-time reverse transcription-polymerase chain reaction. When 3T3-L1 adipocytes were treated with Kochujang extract (KE), the sizes of adipocytes and leptin secretion were decreased. Hormone-sensitive lipase (HSL) was transcriptionally up-regulated at 4 hours, and glycerol secretion was increased at both 4 hours and 24 hours. Moreover, mRNA expression levels of both sterol regulatory element-binding protein 1-c (SREBP-1c) and peroxisome proliferator-activated receptor-gamma (PPAR-gamma), which are critical transcription factors for adipogenesis, were markedly down-regulated. Tumor necrosis factor-alpha (TNF-alpha) is reported to impair pre-adipocyte differentiation and induce lipolysis and apoptosis. KE treatment of 3T3-L1 adipocytes decreased TNF-alpha mRNA levels, but had no apparent affect on apoptosis. Taken together, our study shows that Kochujang decreased lipid accumulation in 3T3-L1 adipocytes by inhibiting adipogenesis through down-regulation of SREBP-1c and PPAR-gamma and by stimulation of lipolysis due to increased HSL activity. TNF-alpha might not be involved in the reduction of lipid accumulation by KE.
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Affiliation(s)
- In-Sook Ahn
- Department of Food Science and Nutrition, Pusan National University, Busan, Korea
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96
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Gregori C, Guillet-Deniau I, Girard J, Decaux JF, Pichard AL. Insulin regulation of glucokinase gene expression: evidence against a role for sterol regulatory element binding protein 1 in primary hepatocytes. FEBS Lett 2005; 580:410-4. [PMID: 16380121 DOI: 10.1016/j.febslet.2005.12.032] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2005] [Revised: 12/09/2005] [Accepted: 12/09/2005] [Indexed: 11/21/2022]
Abstract
Liver key genes for carbohydrate and lipid homeostasis are regulated by insulin and glucose. The sterol regulatory-element binding protein-1c (SREBP-1c) has emerged as a mediator of insulin effects on gene transcription, particularly on glucokinase (GK). In this paper, we show that despite stimulation of GK promoter transcription by overexpression of mature SREBP-1c, insulin induced GK transcription at least 4h ahead of accumulation of mature SREBP-1c in the nucleus. Importantly, the knockdown of SREBP-1 mRNA using a RNA-interference technique reduced the level of nuclear SREBP-1 protein, diminished fatty acid synthase mRNA level, but did not affect GK and L-pyruvate kinase mRNA levels. We concluded that SREBP-1 is unlikely to be the mediator of the early insulin effect on GK gene transcription.
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Affiliation(s)
- Claudine Gregori
- Département d'Endocrinologie, Institut Cochin, Institut National de la santé et de la Recherche Médicale (INSERM) U567, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche 8104, Université René Descartes, 75014 Paris, France
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97
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Alo PL, Galati GM, Sebastiani V, Ricci F, Visca P, Mariani L, Romagnoli F, Lombardi G, Tondo UDI. Fatty acid synthase expression in Paget's disease of the vulva. Int J Gynecol Pathol 2005; 24:404-8. [PMID: 16175090 DOI: 10.1097/01.pgp.0000170065.53813.81] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We explored the immunohistochemical expression of fatty acid synthase (FAS) in Paget's disease of the vulva (PDV) and its association with clinico-pathological features. FAS is a recently discovered molecule involved in energy supply of normal cells. FAS is also overexpressed in neoplastic tissues because of their increased necessity of energy. Specimens from 20 patients with PDV were immunohistochemically evaluated; increased FAS expression was observed in 7 of 8 patients with invasive PDV (87%), in 3 of 4 patients with microinvasive PDV (75%), and in 1 of 8 patients with noninvasive PDV (12%). Statistical analysis revealed that increased FAS expression was associated with invasive PDV (p = 0.04). To our knowledge, this association of FAS in PDV is the first to be reported in literature. These observations reveal that FAS is a reliable marker of aggressiveness in PDV. The knowledge of FAS statistical association in invasive PDV is an important finding that may stratify these patients in different prognostic groups and determine therapeutic approaches for patient care.
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Affiliation(s)
- Piero L Alo
- Department of Experimental Pathology and Medicine, University of Rome La Sapienza, Rome, Italy.
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98
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Chang Y, Wang J, Lu X, Thewke DP, Mason RJ. KGF induces lipogenic genes through a PI3K and JNK/SREBP-1 pathway in H292 cells. J Lipid Res 2005; 46:2624-35. [PMID: 16162944 DOI: 10.1194/jlr.m500154-jlr200] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lipid synthesis is required for cell growth and is subject to pharmacologic regulation. Keratinocyte growth factor (KGF) stimulates proliferation and lipogenesis in H292 cells, a pulmonary epithelial cancer cell line, but the signaling pathways are not known. KGF stimulated the expression of the transcription factors sterol-regulatory element binding protein-1 (SREBP-1), CCAAT/enhancer binding protein alpha (C/EBPalpha), and C/EBPdelta and two key enzymes involved in lipogenesis, FAS and stearoyl coenzyme A desaturase-1 (SCD-1). We found that KGF induced rapid activation of Akt, p70 S6K, JNK, and extracellular signal-regulated (ERK). Induction of SREBP-1, SCD-1, and FAS by KGF was inhibited by the JNK inhibitor SP600125 and the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 but not by the ERK inhibitor PD98059. Using FAS and SCD-1-luciferase promoter constructs, we observed that KGF stimulated the transcription of these promoters and that exogenous cholesterol inhibited the induction. Mutation of the SREBP-1 binding site in the SCD-1 promoter abolished the effect of KGF on SCD-1 transcription. In addition, overexpression of active SREBP-1 directly stimulated SCD-1 and FAS. Conversely, adenovirus-mediated overexpression of a dominant negative form of SREBP-1 inhibited the KGF effect on FAS and SCD-1 expression. In summary, we conclude that KGF requires both PI3K and JNK signaling pathways to induce SREBP-1, which in turn induces SCD-1 and FAS expression in H292 cells.
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Affiliation(s)
- Yongsheng Chang
- Department of Medicine, National Jewish Medical and Research Center, Denver, CO 80206, USA
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99
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Sandberg MB, Fridriksson J, Madsen L, Rishi V, Vinson C, Holmsen H, Berge RK, Mandrup S. Glucose-induced lipogenesis in pancreatic beta-cells is dependent on SREBP-1. Mol Cell Endocrinol 2005; 240:94-106. [PMID: 16002205 DOI: 10.1016/j.mce.2005.05.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2005] [Revised: 05/13/2005] [Accepted: 05/18/2005] [Indexed: 01/22/2023]
Abstract
High concentrations of glucose induce de novo fatty acid synthesis in pancreatic beta-cells and chronic exposure of elevated glucose and fatty acids synergize to induce accumulation of triglycerides, a phenomenon termed glucolipotoxicity. Here we investigate the role of sterol-regulatory element binding proteins in glucose-induced lipogenesis in the pancreatic beta-cell line INS-1E. We show that glucose induces SREBP-1c expression and SREBP-1 activity independent of insulin secretion and signaling. Using adenoviral expression of SREBP-1c and a SREBP-mutant we show that lipogenic gene expression, de novo fatty acid synthesis and lipid accumulation are induced primarily through sterol-regulatory elements (SREs) and not E-Boxes. Adenoviral expression of a dominant negative SREBP compromises glucose induction of some lipogenic genes and significantly reduces glucose-induction of de novo fatty acid synthesis. Thus, we demonstrate for the first time that SREBP activity is necessary for full glucose induction of de novo fatty acid synthesis in pancreatic beta-cells.
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Affiliation(s)
- Maria B Sandberg
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense
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100
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Abstract
Growth hormone (GH) diminishes adipose tissue mass in vivo and decreases expression and activity of fatty acid synthase (FAS) in adipocytes. GH and prolactin (PRL) are potent activators of STAT5 and exert adipogenic and antiadipogenic effects in adipocytes. In this study, we demonstrate that GH and PRL decrease the mRNA and protein levels of FAS in 3T3-L1 adipocytes. We present evidence that indicates that FAS is repressed at the level of transcription. In addition, PRL responsiveness was shown to exist between -1,594 and -700 of the rat FAS promoter. Moreover, responsiveness to PRL was abolished with mutation of a site at position -908 to -893, which we have shown to bind STAT5A in a PRL-dependent manner. Taken together, these data strongly suggest that PRL directly represses expression of FAS in adipocytes through STAT5A binding to the -908 to -893 site. Furthermore, our results indicate that STAT5A has an antilipogenic function in adipocytes and may contribute to the regulation of energy balance.
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Affiliation(s)
- Jessica C Hogan
- Louisiana State University, Department of Biological Sciences, 202 Life Sciences Bldg., Baton Rouge, LA 70803, USA
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