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Kaimala S, Lootah SS, Mehra N, Kumar CA, Marzooqi SA, Sampath P, Ansari SA, Emerald BS. The Long Non-Coding RNA Obesity-Related (Obr) Contributes To Lipid Metabolism Through Epigenetic Regulation. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2401939. [PMID: 38704700 PMCID: PMC11234455 DOI: 10.1002/advs.202401939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Indexed: 05/07/2024]
Abstract
Obesity is a multifactorial disease that is part of today's epidemic and also increases the risk of other metabolic diseases. Long noncoding RNAs (lncRNAs) provide one tier of regulatory mechanisms to maintain metabolic homeostasis. Although lncRNAs are a significant constituent of the mammalian genome, studies aimed at their metabolic significance, including obesity, are only beginning to be addressed. Here, a developmentally regulated lncRNA, termed as obesity related (Obr), whose expression in metabolically relevant tissues such as skeletal muscle, liver, and pancreas is altered in diet-induced obesity, is identified. The Clone 9 cell line and high-fat diet-induced obese Wistar rats are used as a model system to verify the function of Obr. By using stable expression and antisense oligonucleotide-mediated downregulation of the expression of Obr followed by different molecular biology experiments, its role in lipid metabolism is verified. It is shown that Obr associates with the cAMP response element-binding protein (Creb) and activates different transcription factors involved in lipid metabolism. Its association with the Creb histone acetyltransferase complex, which includes the cAMP response element-binding protein (CBP) and p300, positively regulates the transcription of genes involved in lipid metabolism. In addition, Obr is regulated by Pparγ in response to lipid accumulation.
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Affiliation(s)
- Suneesh Kaimala
- Department of Anatomy, College of Medicine and Health Sciences, UAE University, Al Ain, P.O. Box 15551, UAE
| | - Shareena Saeed Lootah
- Department of Anatomy, College of Medicine and Health Sciences, UAE University, Al Ain, P.O. Box 15551, UAE
| | - Neha Mehra
- Department of Anatomy, College of Medicine and Health Sciences, UAE University, Al Ain, P.O. Box 15551, UAE
| | - Challagandla Anil Kumar
- Department of Anatomy, College of Medicine and Health Sciences, UAE University, Al Ain, P.O. Box 15551, UAE
| | - Saeeda Al Marzooqi
- Department of Pathology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, Abu Dhabi, P.O. Box 15551, UAE
| | - Prabha Sampath
- A*STAR Skin Research Laboratory, Agency for Science Technology & Research (A*STAR), Singapore, 138648, Singapore
- Program in Cancer and Stem Cell Biology, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore
- Genome Institute of Singapore, Agency for Science Technology & Research (A*STAR), Singapore, 138672, Singapore
| | - Suraiya Anjum Ansari
- Department of Biochemistry and Molecular Biology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, Abu Dhabi, P.O. Box 15551, UAE
- Zayed Center for Health Sciences, United Arab Emirates University, Al Ain, Abu Dhabi, P.O. Box 15551, UAE
- ASPIRE Precision Medicine, Research Institute Abu Dhabi, Al Ain, Abu Dhabi, P.O. Box 15551, UAE
| | - Bright Starling Emerald
- Department of Anatomy, College of Medicine and Health Sciences, UAE University, Al Ain, P.O. Box 15551, UAE
- Zayed Center for Health Sciences, United Arab Emirates University, Al Ain, Abu Dhabi, P.O. Box 15551, UAE
- ASPIRE Precision Medicine, Research Institute Abu Dhabi, Al Ain, Abu Dhabi, P.O. Box 15551, UAE
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Liu C, Lin Y, Wang Y, Lin S, Zhou J, Tang H, Yi X, Ma Z, Xia T, Jiang B, Tian F, Ju Z, Liu B, Gu X, Yang Z, Wang W. HuR promotes triglyceride synthesis and intestinal fat absorption. Cell Rep 2024; 43:114238. [PMID: 38748875 DOI: 10.1016/j.celrep.2024.114238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Revised: 04/02/2024] [Accepted: 04/30/2024] [Indexed: 06/01/2024] Open
Abstract
Triacylglyceride (TAG) synthesis in the small intestine determines the absorption of dietary fat, but the underlying mechanisms remain to be further studied. Here, we report that the RNA-binding protein HuR (ELAVL1) promotes TAG synthesis in the small intestine. HuR associates with the 3' UTR of Dgat2 mRNA and intron 1 of Mgat2 pre-mRNA. Association of HuR with Dgat2 3' UTR stabilizes Dgat2 mRNA, while association of HuR with intron 1 of Mgat2 pre-mRNA promotes the processing of Mgat2 pre-mRNA. Intestinal epithelium-specific HuR knockout reduces the expression of DGAT2 and MGAT2, thereby reducing the dietary fat absorption through TAG synthesis and mitigating high-fat-diet (HFD)-induced non-alcoholic fatty liver disease (NAFLD) and obesity. Our findings highlight a critical role of HuR in promoting dietary fat absorption.
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Affiliation(s)
- Cihang Liu
- Department of Anesthesiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing 210008, China; Department of Biochemistry and Molecular Biology, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, School of Basic Medical Sciences, Peking University Health Science Center, 38 Xueyuan Road, Beijing 100191, China
| | - Yunping Lin
- Department of Biochemistry and Molecular Biology, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, School of Basic Medical Sciences, Peking University Health Science Center, 38 Xueyuan Road, Beijing 100191, China
| | - Ying Wang
- Department of Biochemistry and Molecular Biology, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, School of Basic Medical Sciences, Peking University Health Science Center, 38 Xueyuan Road, Beijing 100191, China
| | - Shuyong Lin
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Jing Zhou
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Hao Tang
- National Health Commission Key Laboratory of Cardiovascular Regenerative Medicine, Heart Center of Henan Provincial People's Hospital, Central China Fuwai Hospital of Zhengzhou University, Central China Fuwai Hospital and Central China Branch of National Center for Cardiovascular Diseases, Zhengzhou, Henan 450003, China
| | - Xia Yi
- Department of Biochemistry and Molecular Biology, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, School of Basic Medical Sciences, Peking University Health Science Center, 38 Xueyuan Road, Beijing 100191, China
| | - Zhengliang Ma
- Department of Anesthesiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing 210008, China
| | - Tianjiao Xia
- Medical School, Nanjing University, Nanjing 210093, China
| | - Bin Jiang
- Department of Biochemistry and Molecular Biology, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, School of Basic Medical Sciences, Peking University Health Science Center, 38 Xueyuan Road, Beijing 100191, China
| | - Feng Tian
- Department of Laboratory Animal Science, Peking University Health Science Center, 38 Xueyuan Road, Beijing 100191, China
| | - Zhenyu Ju
- Key Laboratory of Regenerative Medicine of Ministry of Education, Institute of Aging and Regenerative Medicine, Jinan University, Guangzhou 510632, China
| | - Baohua Liu
- Guangdong Key Laboratory of Genome Stability and Human Disease Prevention, Carson International Cancer Center, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Shenzhen University Health Science Center, Shenzhen 518060, China
| | - Xiaoping Gu
- Department of Anesthesiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing 210008, China.
| | - Zhongzhou Yang
- Medical School, Nanjing University, Nanjing 210093, China.
| | - Wengong Wang
- Department of Biochemistry and Molecular Biology, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, School of Basic Medical Sciences, Peking University Health Science Center, 38 Xueyuan Road, Beijing 100191, China; Center for Healthy Aging, Changzhi Medical College, Changzhi 046000, China; Liaoning Technology and Engineering Center for Tumor Immunology and Molecular Theranostics, Collaborative Innovation Center for Age-related Disease, Life Science Institute of Jinzhou Medical University, Jinzhou 121001, Liaoning, China.
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Chen CY, Li Y, Zeng N, He L, Zhang X, Tu T, Tang Q, Alba M, Mir S, Stiles EX, Hong H, Cadenas E, Stolz AA, Li G, Stiles BL. Inhibition of Estrogen-Related Receptor α Blocks Liver Steatosis and Steatohepatitis and Attenuates Triglyceride Biosynthesis. THE AMERICAN JOURNAL OF PATHOLOGY 2021; 191:1240-1254. [PMID: 33894178 PMCID: PMC8261472 DOI: 10.1016/j.ajpath.2021.04.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 03/08/2021] [Accepted: 04/12/2021] [Indexed: 01/02/2023]
Abstract
The estrogen-related receptor (ERR) family of orphan nuclear receptors are transcriptional activators for genes involved in mitochondrial bioenergetics and metabolism. The goal of this study was to explore the role of ERRα in lipid metabolism and the potential effect of inhibiting ERRα on the development of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH). In the current study, three experimental mouse models: high-fat diet, high-carbohydrate diet, and a genetic model of hepatic insulin resistance where the liver hyperinsulinemia signal is mimicked via hepatic deletion of Pten (phosphatase and tensin homolog deleted on chromosome 10), the negative regulator of the insulin/phosphatidylinositol 3-kinase signaling pathway, were used. A recently developed small-molecule inhibitor for ERRα was used to demonstrate that inhibiting ERRα blocked NAFLD development induced by either high-carbohydrate diet or high-fat diet feeding. ERRα inhibition also diminished lipid accumulation and attenuated NASH development in the Pten null mice. Glycerolipid synthesis was discovered as an additional mechanism for ERRα-regulated NAFLD/NASH development and glycerophosphate acyltransferase 4 was identified as a novel transcriptional target of ERRα. In summary, these results establish ERRα as a major transcriptional regulator of lipid biosynthesis in addition to its characterized primary function as a regulator for mitochondrial function. This study recognizes ERRα as a potential target for NAFLD/NASH treatment and elucidates novel signaling pathways regulated by ERRα.
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Affiliation(s)
- Chien-Yu Chen
- Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California
| | - Yang Li
- Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California
| | - Ni Zeng
- Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California
| | - Lina He
- Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California
| | - Xinwen Zhang
- Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California
| | - Taojian Tu
- Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California
| | - Qi Tang
- Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California
| | - Mario Alba
- Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California
| | - Sabrina Mir
- Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California
| | - Eileen X Stiles
- Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California
| | - Handan Hong
- Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California
| | - Enrique Cadenas
- Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California; Department of Biochemistry, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Andrew A Stolz
- Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Gang Li
- Faculty of Health Sciences, University of Macau, Macau
| | - Bangyan L Stiles
- Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California; Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, California.
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Jin W, Zhao Y, Zhai B, Li Y, Fan S, Yuan P, Sun G, Jiang R, Wang Y, Liu X, Tian Y, Kang X, Li G. Characteristics and expression profiles of circRNAs during abdominal adipose tissue development in Chinese Gushi chickens. PLoS One 2021; 16:e0249288. [PMID: 33857153 PMCID: PMC8049301 DOI: 10.1371/journal.pone.0249288] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Accepted: 03/15/2021] [Indexed: 12/14/2022] Open
Abstract
Circular RNAs (circRNAs) play important roles in adipogenesis. However, studies on circRNA expression profiles associated with the development of abdominal adipose tissue are lacking in chickens. In this study, 12 cDNA libraries were constructed from the abdominal adipose tissue of Chinese domestic Gushi chickens at 6, 14, 22, and 30 weeks. A total of 1,766 circRNAs were identified by Illumina HiSeq 2500 sequencing. These circRNAs were primarily distributed on chr1 through chr10 and sex chromosomes, and 84.95% of the circRNAs were from gene exons. Bioinformatic analysis showed that each circRNA has 35 miRNA binding sites on average, and 62.71% have internal ribosome entry site (IRES) elements. Meanwhile, these circRNAs were primarily concentrated in TPM < 0.1 and TPM > 60, and their numbers accounted for 18.90% and 80.51%, respectively, exhibiting specific expression patterns in chicken abdominal adipose tissue. In addition, 275 differentially expressed (DE) circRNAs were identified by comparison analysis. Functional enrichment analysis showed that the parental genes of DE circRNAs were primarily involved in biological processes and pathways related to lipid metabolism, such as regulation of fat cell differentiation, fatty acid homeostasis, and triglyceride homeostasis, as well as fatty acid biosynthesis, fatty acid metabolism, and glycerolipid metabolism. Furthermore, ceRNA regulatory networks related to abdominal adipose development were constructed. The results of this study indicated that circRNAs can regulate lipid metabolism, adipocyte proliferation and differentiation, and cell junctions during abdominal adipose tissue development in chickens through complex ceRNA networks between circRNAs, miRNAs, genes, and pathways. The results of this study may help to expand the number of known circRNAs in abdominal adipose tissue and provide a valuable resource for further research on the function of circRNAs in chicken abdominal adipose tissue.
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Affiliation(s)
- Wenjiao Jin
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, Henan Province, P.R. China
| | - Yinli Zhao
- College of Biological Engineering, Henan University of Technology, Zhengzhou, Henan Province, P.R. China
| | - Bin Zhai
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, Henan Province, P.R. China
| | - Yuanfang Li
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, Henan Province, P.R. China
| | - Shengxin Fan
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, Henan Province, P.R. China
| | - Pengtao Yuan
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, Henan Province, P.R. China
| | - Guirong Sun
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, Henan Province, P.R. China
| | - Ruirui Jiang
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, Henan Province, P.R. China
| | - Yanbin Wang
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, Henan Province, P.R. China
| | - Xiaojun Liu
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, Henan Province, P.R. China
| | - Yadong Tian
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, Henan Province, P.R. China
| | - Xiangtao Kang
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, Henan Province, P.R. China
| | - Guoxi Li
- College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, Henan Province, P.R. China
- * E-mail:
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5
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Xie G, Wang Y, Xu Q, Hu M, Zhu J, Bai W, Lin Y. Knockdown of adiponectin promotes the adipogenesis of goat intramuscular preadipocytes. Anim Biotechnol 2020; 33:408-416. [PMID: 32755436 DOI: 10.1080/10495398.2020.1800484] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Intramuscular fat (IMF) content determined by the intramuscular preadipocytes differentiation has a huge influence on the sensory quality traits of meats. It was reported that the adiponectin (ADIPOQ) gene could promote adipocytes differentiation, but the underlying molecular and functional characterization of the ADIPOQ for regulating goat IMF deposition remained unknown. Herein, the knockdown of ADIPOQ was mediated by siRNAs during goat intramuscular preadipocytes differentiation. Also, the qRT-PCR technique was performed to detect the mRNA levels of target genes in multiply experiment groups. These results showed that the ADIPOQ was expressed more than ∼400 folds in subcutaneous adipose tissue compared to that of heart tissue, and the mRNA level of ADIPOQ reached a peak at Hour 60 during the differentiation process, while at Hour 36 did ADIPOR1 and ADIPOR2. Moreover, the knockdown of ADIPOQ promoted the intramuscular preadipocytes differentiation and accelerated the lipid accumulation in the mature adipocytes with down-regulating the ADIPOR1 and preadipocyte factor 1 (Pref-1) mRNA levels and up-regulating the mRNA expression levels of the CAAT/enhancer-binding proteins (C/EBPs) and transcription factor peroxisomal proliferator-activated receptor γ (PPARγ), etc. Our study will provide a new opposite insight that the inhibition of ADIPOQ expression during intramuscular preadipocytes differentiation promotes goat IMF deposition.
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Affiliation(s)
- Guangjie Xie
- Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization, Ministry of Education, Chengdu, China.,Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization, Sichuan Province, Chengdu, China.,College of Life Science and Technique, Southwest Minzu University, Chengdu, China
| | - Yong Wang
- Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization, Ministry of Education, Chengdu, China.,Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization, Sichuan Province, Chengdu, China
| | - Qing Xu
- Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization, Ministry of Education, Chengdu, China.,Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization, Sichuan Province, Chengdu, China.,College of Life Science and Technique, Southwest Minzu University, Chengdu, China
| | - Meng Hu
- College of Life Science and Technique, Southwest Minzu University, Chengdu, China
| | - Jiangjiang Zhu
- Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization, Ministry of Education, Chengdu, China.,Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization, Sichuan Province, Chengdu, China
| | - Wenlin Bai
- College of Animal Science & Veterinary Medicine, Shenyang Agricultural University, Shenyang, China
| | - Yaqiu Lin
- Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization, Ministry of Education, Chengdu, China.,Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization, Sichuan Province, Chengdu, China.,College of Life Science and Technique, Southwest Minzu University, Chengdu, China
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Gentiopicroside isolated from Gentiana scabra Bge. inhibits adipogenesis in 3T3-L1 cells and reduces body weight in diet-induced obese mice. Bioorg Med Chem Lett 2019; 29:1699-1704. [PMID: 31130265 DOI: 10.1016/j.bmcl.2019.05.038] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 04/18/2019] [Accepted: 05/18/2019] [Indexed: 12/30/2022]
Abstract
Gentiopicroside is a major active component of the Gentiana scabra Bge., which is commonly used as herbal medicine for the treatment of inflammation in Asia. Gentiopicroside significantly down-regulated expression of key adipogenic transcription factors (PPARγ, C/EBPα, SREBP-1c) and dose-dependently inhibited the lipid uptake-related gene (LPL), fatty acid transport-related gene (FABP4) and triglyceride (TG) synthesis-related gene (DGAT2), as well as fatty acid synthesis-related genes (FAS, SCD1), which resulted in reduced intracellular lipid droplet accumulation and TG content in 3T3-L1 cells. Gentiopicroside also down-regulated expression of inflammatory cytokine genes (NFκB1, TNFα, IL6) compared with vehicle. Oral administration of gentiopicroside (50 mg/kg) in mice fed with high-fat diet for 12 weeks resulted in reduced body weight and visceral fat mass compared with the control group. Overall, the results of this study showed that gentiopicroside had positive anti-obesity effects by regulating the expression of adipogenesis/lipogenesis-related genes and inflammatory genes in 3T3-L1, and that it effectively reduced body weight and visceral fat mass in vivo.
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Lee J, Ridgway ND. Substrate channeling in the glycerol-3-phosphate pathway regulates the synthesis, storage and secretion of glycerolipids. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1865:158438. [PMID: 30959116 DOI: 10.1016/j.bbalip.2019.03.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 03/26/2019] [Accepted: 03/27/2019] [Indexed: 01/16/2023]
Abstract
The successive acylation of glycerol-3-phosphate (G3P) by glycerol-3-phosphate acyltransferases and acylglycerol-3-phosphate acyltransferases produces phosphatidic acid (PA), a precursor for CDP-diacylglycerol-dependent phospholipid synthesis. PA is further dephosphorylated by LIPINs to produce diacylglycerol (DG), a substrate for the synthesis of triglyceride (TG) by DG acyltransferases and a precursor for phospholipid synthesis via the CDP-choline and CDP-ethanolamine (Kennedy) pathways. The channeling of fatty acids into TG for storage in lipid droplets and secretion in lipoproteins or phospholipids for membrane biogenesis is dependent on isoform expression, activity and localization of G3P pathway enzymes, as well as dietary and hormonal and tissue-specific factors. Here, we review the mechanisms that control partitioning of substrates into lipid products of the G3P pathway.
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Affiliation(s)
- Jonghwa Lee
- Atlantic Research Center, Depts. of Pediatrics and Biochemistry & Molecular Biology, Dalhousie University, Halifax, NS, Canada
| | - Neale D Ridgway
- Atlantic Research Center, Depts. of Pediatrics and Biochemistry & Molecular Biology, Dalhousie University, Halifax, NS, Canada.
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Effect of lncRNA HOXA11-AS1 on adipocyte differentiation in human adipose-derived stem cells. Biochem Biophys Res Commun 2017; 495:1878-1884. [PMID: 29217197 DOI: 10.1016/j.bbrc.2017.12.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 12/01/2017] [Indexed: 01/03/2023]
Abstract
AIMS To determine the role of lncRNA HOXA11-AS1 on adipocyte differentiation. METHODS Human adipose-derived stem cells (hADSCs) were isolated from adipose tissues of patients and cultured in vitro, followed by knockdown of HOXA11-AS1. Then, adipocyte differentiation and expression of adipogenic-related genes (CEBP-α, DGAT2, CIDEC, and perilipin) were measured by RT-qPCR and Western blot. RESULTS We demonstrated that knockdown of HOXA11-AS1 inhibited adipocyte differentiation, leading to suppression of adipogenic-related gene (CEBP-α, DGAT2, CIDEC, and perilipin) transcription, as well as decreased lipid accumulation in hADSCs. In addition, lncRNA HOXA11-AS1 was highly expressed in obese patients and significantly increased during the process of adipocyte differentiation. CONCLUSION The results provide new insight into the molecular mechanism by which lncRNA HOXA11-AS1 is involved in adipogenesis and may have implications for the treatment of obesity and associated disorders.
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Wang H, Airola MV, Reue K. How lipid droplets "TAG" along: Glycerolipid synthetic enzymes and lipid storage. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:1131-1145. [PMID: 28642195 PMCID: PMC5688854 DOI: 10.1016/j.bbalip.2017.06.010] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 06/15/2017] [Accepted: 06/15/2017] [Indexed: 02/06/2023]
Abstract
Triacylglycerols (TAG) serve as the predominant form of energy storage in mammalian cells, and TAG synthesis influences conditions such as obesity, fatty liver, and insulin resistance. In most tissues, the glycerol 3-phosphate pathway enzymes are responsible for TAG synthesis, and the regulation and function of these enzymes is therefore important for metabolic homeostasis. Here we review the sites and regulation of glycerol-3-phosphate acyltransferase (GPAT), acylglycerol-3-phosphate acyltransferase (AGPAT), lipin phosphatidic acid phosphatase (PAP), and diacylglycerol acyltransferase (DGAT) enzyme action. We highlight the critical roles that these enzymes play in human health by reviewing Mendelian disorders that result from mutation in the corresponding genes. We also summarize the valuable insights that genetically engineered mouse models have provided into the cellular and physiological roles of GPATs, AGPATs, lipins and DGATs. Finally, we comment on the status and feasibility of therapeutic approaches to metabolic disease that target enzymes of the glycerol 3-phosphate pathway. This article is part of a Special Issue entitled: Recent Advances in Lipid Droplet Biology edited by Rosalind Coleman and Matthijs Hesselink.
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Affiliation(s)
- Huan Wang
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Michael V Airola
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, United States
| | - Karen Reue
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States; Molecular Biology Institute, University of California, Los Angeles, CA, United States.
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Engin A. Fat Cell and Fatty Acid Turnover in Obesity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 960:135-160. [PMID: 28585198 DOI: 10.1007/978-3-319-48382-5_6] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The ratio of free fatty acid (FFA) turnover decreases significantly with the expansion of white adipose tissue. Adipose tissue and dietary saturated fatty acid levels significantly correlate with an increase in fat cell size and number. Inhibition of adipose triglyceride lipase leads to an accumulation of triglyceride, whereas inhibition of hormone-sensitive lipase leads to the accumulation of diacylglycerol. The G0/G1 switch gene 2 increases lipid content in adipocytes and promotes adipocyte hypertrophy through the restriction of triglyceride turnover. Excess triacylglycerols (TAGs), sterols and sterol esters are surrounded by the phospholipid monolayer surface and form lipid droplets. Following the release of lipid droplets from endoplasmic reticulum, cytoplasmic lipid droplets increase their volume either by local TAG synthesis or by homotypic fusion. The number and the size of lipid droplet distribution is correlated with obesity. Obesity-associated adipocyte death exhibits feature of necrosis-like programmed cell death. NOD-like receptors family pyrin domain containing 3 (NLRP3) inflammasome-dependent caspase-1 activation in hypertrophic adipocytes induces obese adipocyte death by pyroptosis. Actually adipocyte death may be a prerequisite for the transition from hypertrophic to hyperplastic obesity. Major transcriptional factors, CCAAT/enhancer-binding proteins beta and delta, play a central role in the subsequent induction of critical regulators, peroxisome-proliferator-activated receptor gamma, CCAAT/enhancer-binding protein alpha and sterol regulatory element-binding protein 1, in the transcriptional control of adipogenesis in obesity.Collectively, in this chapter the concept of adipose tissue remodeling in response to adipocyte death or adipogenesis, and the complexity of lipid droplet interactions with the other cellular organelles are reviewed. Furthermore, in addition to lipid droplet growth, the functional link between the adipocyte-specific lipid droplet-associated protein and fatty acid turn-over is also debated.
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Affiliation(s)
- Atilla Engin
- Faculty of Medicine, Department of General Surgery, Gazi University, Besevler, Ankara, Turkey. .,, Mustafa Kemal Mah. 2137. Sok. 8/14, 06520, Cankaya, Ankara, Turkey.
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11
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Irshad Z, Dimitri F, Christian M, Zammit VA. Diacylglycerol acyltransferase 2 links glucose utilization to fatty acid oxidation in the brown adipocytes. J Lipid Res 2017; 58:15-30. [PMID: 27836993 PMCID: PMC5234708 DOI: 10.1194/jlr.m068197] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 10/18/2016] [Indexed: 01/03/2023] Open
Abstract
Brown adipose tissue uptake of glucose and fatty acids is very high during nonshivering thermogenesis. Adrenergic stimulation markedly increases glucose uptake, de novo lipogenesis, and FA oxidation simultaneously. The mechanism that enables this concerted response has hitherto been unknown. Here, we find that in primary brown adipocytes and brown adipocyte-derived cell line (IMBAT-1), acute inhibition and longer-term knockdown of DGAT2 links the increased de novo synthesis of fatty acids from glucose to a pool of TAG that is simultaneously hydrolyzed, providing FA for mitochondrial oxidation. DGAT1 does not contribute to this pathway, but uses exogenous FA and glycerol to synthesize a functionally distinct pool of TAG to which DGAT2 also contributes. The DGAT2-dependent channelling of 14C from glucose into TAG and CO2 was reproduced in β3-agonist-stimulated primary brown adipocytes. Knockdown of DGAT2 in IMBAT-1 affected the mRNA levels of UCP1 and genes important in FA activation and esterification. Therefore, in β3-agonist activated brown adipocytes, DGAT2 specifically enables channelling of de novo synthesized FA into a rapidly mobilized pool of TAG, which is simultaneously hydrolyzed to provide substrates for mitochondrial fatty acid oxidation.
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Affiliation(s)
- Zehra Irshad
- Translational and Experimental Medicine, Division of Biomedical Sciences, Warwick Medical School, CV4 7AL, United Kingdom
| | - Federica Dimitri
- Translational and Experimental Medicine, Division of Biomedical Sciences, Warwick Medical School, CV4 7AL, United Kingdom
| | - Mark Christian
- Translational and Experimental Medicine, Division of Biomedical Sciences, Warwick Medical School, CV4 7AL, United Kingdom
| | - Victor A Zammit
- Translational and Experimental Medicine, Division of Biomedical Sciences, Warwick Medical School, CV4 7AL, United Kingdom
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12
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Segerer G, Hadamek K, Zundler M, Fekete A, Seifried A, Mueller MJ, Koentgen F, Gessler M, Jeanclos E, Gohla A. An essential developmental function for murine phosphoglycolate phosphatase in safeguarding cell proliferation. Sci Rep 2016; 6:35160. [PMID: 27731369 PMCID: PMC5059750 DOI: 10.1038/srep35160] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 09/26/2016] [Indexed: 12/20/2022] Open
Abstract
Mammalian phosphoglycolate phosphatase (PGP) is thought to target phosphoglycolate, a 2-deoxyribose fragment derived from the repair of oxidative DNA lesions. However, the physiological role of this activity and the biological function of the DNA damage product phosphoglycolate is unknown. We now show that knockin replacement of murine Pgp with its phosphatase-inactive PgpD34N mutant is embryonically lethal due to intrauterine growth arrest and developmental delay in midgestation. PGP inactivation attenuated triosephosphate isomerase activity, increased triglyceride levels at the expense of the cellular phosphatidylcholine content, and inhibited cell proliferation. These effects were prevented under hypoxic conditions or by blocking phosphoglycolate release from damaged DNA. Thus, PGP is essential to sustain cell proliferation in the presence of oxygen. Collectively, our findings reveal a previously unknown mechanism coupling a DNA damage repair product to the control of intermediary metabolism and cell proliferation.
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Affiliation(s)
- Gabriela Segerer
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Strasse 9, D-97078 Würzburg, Germany.,Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Strasse 2, D-97080 Würzburg, Germany
| | - Kerstin Hadamek
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Strasse 9, D-97078 Würzburg, Germany.,Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Strasse 2, D-97080 Würzburg, Germany
| | - Matthias Zundler
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Strasse 9, D-97078 Würzburg, Germany.,Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Strasse 2, D-97080 Würzburg, Germany
| | - Agnes Fekete
- Institute of Pharmaceutical Biology, University of Würzburg, Julius-von-Sachs-Platz 2, D-97082 Würzburg, Germany
| | - Annegrit Seifried
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Strasse 9, D-97078 Würzburg, Germany.,Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Strasse 2, D-97080 Würzburg, Germany
| | - Martin J Mueller
- Institute of Pharmaceutical Biology, University of Würzburg, Julius-von-Sachs-Platz 2, D-97082 Würzburg, Germany
| | - Frank Koentgen
- Ozgene Pty Ltd, PO Box 1128, Bentley DC, WA 6983, Australia
| | - Manfred Gessler
- Theodor-Boveri-Institute/Biocenter, Developmental Biochemistry, Am Hubland, University of Würzburg, D-97074 Würzburg, Germany.,Comprehensive Cancer Center Mainfranken, University of Würzburg, Josef-Schneider-Strasse 6, D-97080 Würzburg, Germany
| | - Elisabeth Jeanclos
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Strasse 9, D-97078 Würzburg, Germany.,Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Strasse 2, D-97080 Würzburg, Germany
| | - Antje Gohla
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Strasse 9, D-97078 Würzburg, Germany.,Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Strasse 2, D-97080 Würzburg, Germany
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13
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Diacylglycerol acyltransferase-2 and monoacylglycerol acyltransferase-2 are ubiquitinated proteins that are degraded by the 26S proteasome. Biochem J 2016; 473:3621-3637. [DOI: 10.1042/bcj20160418] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 08/16/2016] [Indexed: 01/20/2023]
Abstract
Acyl-CoA:1,2-diacylglycerol acyltransferase (DGAT)-2 is one of the two DGAT enzymes that catalyzes the synthesis of triacylglycerol, which is an important form of stored energy for eukaryotic organisms. There is currently limited information available regarding how DGAT2 and triacylglycerol synthesis are regulated. Recent studies have indicated that DGAT2 can be regulated by changes in gene expression. How DGAT2 is regulated post-transcriptionally remains less clear. In this study, we demonstrated that DGAT2 is a very unstable protein and is rapidly degraded in an ubiquitin-dependent manner via the proteasome. Many of the 25 lysines present in DGAT2 appeared to be involved in promoting its degradation. However, the six C-terminal lysines were the most important in regulating stability. We also demonstrated that acyl-CoA:monoacylglycerol acyltransferase (MGAT)-2, an enzyme with extensive sequence homology to DGAT2 that catalyzes the synthesis of diacylglycerol, was also ubiquitinated. However, MGAT2 was found to be much more stable than DGAT2. Interestingly, when co-expressed, MGAT2 appeared to stabilize DGAT2. Finally, we found that both DGAT2 and MGAT2 are substrates of the endoplasmic reticulum-associated degradation pathway.
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14
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Shin E, Bae JS, Han JY, Lee J, Jeong YS, Lee HJ, Ahn YH, Cha JY. Hepatic DGAT2 gene expression is regulated by the synergistic action of ChREBP and SP1 in HepG2 cells. Anim Cells Syst (Seoul) 2016. [DOI: 10.1080/19768354.2015.1131738] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
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15
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Caffeic Acid Phenethyl Ester Regulates PPAR's Levels in Stem Cells-Derived Adipocytes. PPAR Res 2016; 2016:7359521. [PMID: 26904104 PMCID: PMC4745343 DOI: 10.1155/2016/7359521] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 12/30/2015] [Indexed: 01/20/2023] Open
Abstract
Hypertrophic obesity inhibits activation of peroxisome proliferators-activated receptor gamma (PPARγ), considered the key mediator of the fully differentiated and insulin sensitive adipocyte phenotype. We examined the effects of Caffeic Acid Phenethyl Ester (Cape), isolated from propolis, a honeybee hive product, on Adipose Stem Cells (ASCs) differentiation to the adipocyte lineage. Finally we tested the effects of Cape on insulin-resistant adipocytes. Quantification of Oil Red O-stained cells showed that lipid droplets decreased following Cape treatment as well as radical oxygen species formation. Additionally, exposure of ASC to high glucose levels decreased adiponectin and increased proinflammatory cytokines mRNA levels, which were reversed by Cape-mediated increase of insulin sensitivity. Cape treatment resulted in decreased triglycerides synthesis and increased beta-oxidation. Exposure of ASCs to Lipopolysaccharide (LPS) induced a reduction of PPARγ, an increase of IL-6 levels associated with a well-known stimulation of lipolysis; Cape partially attenuated the LPS-mediated effects. These observations reveal the main role of PPARγ in the adipocyte function and during ASC differentiation. As there is now substantial interest in functional food and nutraceutical products, the observed therapeutic value of Cape in insulin-resistance related diseases should be taken into consideration.
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16
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Popov VB, Jornayvaz FR, Akgul EO, Kanda S, Jurczak MJ, Zhang D, Abudukadier A, Majumdar SK, Guigni B, Petersen KF, Manchem VP, Bhanot S, Shulman GI, Samuel VT. Second-generation antisense oligonucleotides against β-catenin protect mice against diet-induced hepatic steatosis and hepatic and peripheral insulin resistance. FASEB J 2015; 30:1207-17. [PMID: 26644352 DOI: 10.1096/fj.15-271999] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 11/16/2015] [Indexed: 12/24/2022]
Abstract
Although mutations in the Wnt/β-catenin signaling pathway are linked with the metabolic syndrome and type 2 diabetes in humans, the mechanism is unclear. High-fat-fed male C57BL/6 mice were treated for 4 wk with a 2'-O-methoxyethyl chimeric antisense oligonucleotide (ASO) to decrease hepatic and adipose expression of β-catenin. β-Catenin mRNA decreased by ≈80% in the liver and by 70% in white adipose tissue relative to control ASO-treated mice. β-Catenin ASO improved hepatic insulin sensitivity and increased insulin-stimulated whole body glucose metabolism, as assessed during hyperinsulinemic-euglycemic clamp in awake mice. β-Catenin ASO altered hepatic lipid composition in high-fat-fed mice. There were reductions in hepatic triglyceride (44%, P < 0.05) and diacylglycerol content (60%, P < 0.01) but a 30% increase in ceramide content (P < 0.001). The altered lipid content was attributed to decreased expression of sn-1,2 diacylglycerol acyltransferase and mitochondrial acyl-CoA:glycerol-sn-3-phosphate acyltransferase and an increase in serine palmitoyl transferase. The decrease in cellular diacyglycerol was associated with a 33% decrease in PKCε activation (P < 0.05) and 64% increase in Akt2 phosphorylation (P < 0.05). In summary, Reducing β-catenin expression decreases expression of enzymes involved in hepatic fatty acid esterification, ameliorates hepatic steatosis and lipid-induced insulin resistance.
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Affiliation(s)
- Violeta B Popov
- *Department of Internal Medicine, Department of Cellular and Molecular Physiology, and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut, USA; West Haven Veterans Affairs Medical Center, West Haven, Connecticut, USA; and ISIS Pharmaceuticals, Carlsbad, California, USA
| | - Francois R Jornayvaz
- *Department of Internal Medicine, Department of Cellular and Molecular Physiology, and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut, USA; West Haven Veterans Affairs Medical Center, West Haven, Connecticut, USA; and ISIS Pharmaceuticals, Carlsbad, California, USA
| | - Emin O Akgul
- *Department of Internal Medicine, Department of Cellular and Molecular Physiology, and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut, USA; West Haven Veterans Affairs Medical Center, West Haven, Connecticut, USA; and ISIS Pharmaceuticals, Carlsbad, California, USA
| | - Shoichi Kanda
- *Department of Internal Medicine, Department of Cellular and Molecular Physiology, and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut, USA; West Haven Veterans Affairs Medical Center, West Haven, Connecticut, USA; and ISIS Pharmaceuticals, Carlsbad, California, USA
| | - Michael J Jurczak
- *Department of Internal Medicine, Department of Cellular and Molecular Physiology, and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut, USA; West Haven Veterans Affairs Medical Center, West Haven, Connecticut, USA; and ISIS Pharmaceuticals, Carlsbad, California, USA
| | - Dongyan Zhang
- *Department of Internal Medicine, Department of Cellular and Molecular Physiology, and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut, USA; West Haven Veterans Affairs Medical Center, West Haven, Connecticut, USA; and ISIS Pharmaceuticals, Carlsbad, California, USA
| | - Abulizi Abudukadier
- *Department of Internal Medicine, Department of Cellular and Molecular Physiology, and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut, USA; West Haven Veterans Affairs Medical Center, West Haven, Connecticut, USA; and ISIS Pharmaceuticals, Carlsbad, California, USA
| | - Sachin K Majumdar
- *Department of Internal Medicine, Department of Cellular and Molecular Physiology, and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut, USA; West Haven Veterans Affairs Medical Center, West Haven, Connecticut, USA; and ISIS Pharmaceuticals, Carlsbad, California, USA
| | - Blas Guigni
- *Department of Internal Medicine, Department of Cellular and Molecular Physiology, and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut, USA; West Haven Veterans Affairs Medical Center, West Haven, Connecticut, USA; and ISIS Pharmaceuticals, Carlsbad, California, USA
| | - Kitt Falk Petersen
- *Department of Internal Medicine, Department of Cellular and Molecular Physiology, and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut, USA; West Haven Veterans Affairs Medical Center, West Haven, Connecticut, USA; and ISIS Pharmaceuticals, Carlsbad, California, USA
| | - Vara Prasad Manchem
- *Department of Internal Medicine, Department of Cellular and Molecular Physiology, and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut, USA; West Haven Veterans Affairs Medical Center, West Haven, Connecticut, USA; and ISIS Pharmaceuticals, Carlsbad, California, USA
| | - Sanjay Bhanot
- *Department of Internal Medicine, Department of Cellular and Molecular Physiology, and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut, USA; West Haven Veterans Affairs Medical Center, West Haven, Connecticut, USA; and ISIS Pharmaceuticals, Carlsbad, California, USA
| | - Gerald I Shulman
- *Department of Internal Medicine, Department of Cellular and Molecular Physiology, and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut, USA; West Haven Veterans Affairs Medical Center, West Haven, Connecticut, USA; and ISIS Pharmaceuticals, Carlsbad, California, USA
| | - Varman T Samuel
- *Department of Internal Medicine, Department of Cellular and Molecular Physiology, and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut, USA; West Haven Veterans Affairs Medical Center, West Haven, Connecticut, USA; and ISIS Pharmaceuticals, Carlsbad, California, USA
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17
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Lyssimachou A, Santos JG, André A, Soares J, Lima D, Guimarães L, Almeida CMR, Teixeira C, Castro LFC, Santos MM. The Mammalian "Obesogen" Tributyltin Targets Hepatic Triglyceride Accumulation and the Transcriptional Regulation of Lipid Metabolism in the Liver and Brain of Zebrafish. PLoS One 2015; 10:e0143911. [PMID: 26633012 PMCID: PMC4669123 DOI: 10.1371/journal.pone.0143911] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 11/11/2015] [Indexed: 12/18/2022] Open
Abstract
Recent findings indicate that different Endocrine Disrupting Chemicals (EDCs) interfere with lipid metabolic pathways in mammals and promote fat accumulation, a previously unknown site of action for these compounds. The antifoulant and environmental pollutant tributyltin (TBT), which causes imposex in gastropod snails, induces an “obesogenic” phenotype in mammals, through the activation of the nuclear receptors retinoid X receptor (RXR) and peroxisome proliferator-activated receptor gamma (PPARγ). In teleosts, the effects of TBT on the lipid metabolism are poorly understood, particularly following exposure to low, environmental concentrations. In this context, the present work shows that exposure of zebrafish to 10 and 50 ng/L of TBT (as Sn) from pre-hatch to 9 months of age alters the body weight, condition factor, hepatosomatic index and hepatic triglycerides in a gender and dose related manner. Furthermore, TBT modulated the transcription of key lipid regulating factors and enzymes involved in adipogenesis, lipogenesis, glucocorticoid metabolism, growth and development in the brain and liver of exposed fish, revealing sexual dimorphic effects in the latter. Overall, the present study shows that the model mammalian obesogen TBT interferes with triglyceride accumulation and the transcriptional regulation of lipid metabolism in zebrafish and indentifies the brain lipogenic transcription profile of fish as a new target of this compound.
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Affiliation(s)
- Angeliki Lyssimachou
- CIMAR/CIIMAR-AL, Interdisciplinary Centre of Marine and Environmental Research, Rua dos Bragas 289, 4050–123, Porto, Portugal
- * E-mail: (AL); (LFCC); (MMS)
| | - Joana G. Santos
- CIMAR/CIIMAR-AL, Interdisciplinary Centre of Marine and Environmental Research, Rua dos Bragas 289, 4050–123, Porto, Portugal
| | - Ana André
- CIMAR/CIIMAR-AL, Interdisciplinary Centre of Marine and Environmental Research, Rua dos Bragas 289, 4050–123, Porto, Portugal
| | - Joana Soares
- CIMAR/CIIMAR-AL, Interdisciplinary Centre of Marine and Environmental Research, Rua dos Bragas 289, 4050–123, Porto, Portugal
| | - Daniela Lima
- CIMAR/CIIMAR-AL, Interdisciplinary Centre of Marine and Environmental Research, Rua dos Bragas 289, 4050–123, Porto, Portugal
| | - Laura Guimarães
- CIMAR/CIIMAR-AL, Interdisciplinary Centre of Marine and Environmental Research, Rua dos Bragas 289, 4050–123, Porto, Portugal
| | - C. Marisa R. Almeida
- CIMAR/CIIMAR-AL, Interdisciplinary Centre of Marine and Environmental Research, Rua dos Bragas 289, 4050–123, Porto, Portugal
| | - Catarina Teixeira
- CIMAR/CIIMAR-AL, Interdisciplinary Centre of Marine and Environmental Research, Rua dos Bragas 289, 4050–123, Porto, Portugal
| | - L. Filipe C. Castro
- CIMAR/CIIMAR-AL, Interdisciplinary Centre of Marine and Environmental Research, Rua dos Bragas 289, 4050–123, Porto, Portugal
- * E-mail: (AL); (LFCC); (MMS)
| | - Miguel M. Santos
- CIMAR/CIIMAR-AL, Interdisciplinary Centre of Marine and Environmental Research, Rua dos Bragas 289, 4050–123, Porto, Portugal
- FCUP–Department of Biology, Faculty of Sciences, University of Porto, Porto, Portugal
- * E-mail: (AL); (LFCC); (MMS)
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18
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Ganji SH, Kashyap ML, Kamanna VS. Niacin inhibits fat accumulation, oxidative stress, and inflammatory cytokine IL-8 in cultured hepatocytes: Impact on non-alcoholic fatty liver disease. Metabolism 2015; 64:982-90. [PMID: 26024755 DOI: 10.1016/j.metabol.2015.05.002] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 04/06/2015] [Accepted: 05/04/2015] [Indexed: 12/21/2022]
Abstract
OBJECTIVE Non-alcoholic fatty liver disease (NAFLD) is a common disorder characterized by excessive hepatic fat accumulation, production of reactive oxygen species (ROS), inflammation and potentially resulting in non-alcoholic steatohepatitis (NASH), cirrhosis and end-stage liver disease. Recently, we have shown that niacin significantly prevented hepatic steatosis and regressed pre-existing steatosis in high-fat fed rat model of NAFLD. To gain further insight into the cellular mechanisms, this study investigated the effect of niacin on human hepatocyte fat accumulation, ROS production, and inflammatory mediator IL-8 secretion. MATERIALS AND METHODS Human hepatoblastoma cell line HepG2 or human primary hepatocytes were first stimulated with palmitic acid followed by treatment with niacin or control for 24 h. RESULTS The data indicated that niacin (at 0.25 and 0.5 mmol/L doses) significantly inhibited palmitic acid-induced fat accumulation in human hepatocytes by 45-62%. This effect was associated with inhibition of diacylglycerol acyltransferase 2 (DGAT2) mRNA expression without affecting the mRNA expression of fatty acid synthase (FAS) and carnitine palmitoyltransferase 1 (CPT1). Niacin attenuated hepatocyte ROS production and it also inhibited NADPH oxidase activity. Niacin reduced palmitic acid-induced IL-8 levels. CONCLUSIONS These findings suggest that niacin, through inhibiting hepatocyte DGAT2 and NADPH oxidase activity, attenuates hepatic fat accumulation and ROS production respectively. Decreased ROS production, at least in part, may have contributed to the inhibition of pro-inflammatory IL-8 levels. These mechanistic studies may be useful for the clinical development of niacin and niacin-related compounds for the treatment of NAFLD/NASH and its complications.
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Affiliation(s)
- Shobha H Ganji
- Department of Veterans Affairs Healthcare System, Long Beach, CA; University of California, Irvine, CA
| | - Moti L Kashyap
- Department of Veterans Affairs Healthcare System, Long Beach, CA; University of California, Irvine, CA
| | - Vaijinath S Kamanna
- Department of Veterans Affairs Healthcare System, Long Beach, CA; University of California, Irvine, CA.
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19
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Choi YJ, Lee CH, Lee KY, Jung SH, Lee BH. Increased hepatic Fatty Acid uptake and esterification contribute to tetracycline-induced steatosis in mice. Toxicol Sci 2015; 145:273-82. [PMID: 25745068 DOI: 10.1093/toxsci/kfv049] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Tetracycline induces microvesicular steatosis, which has a poor long-term prognosis and a higher risk of steatohepatitis development compared with macrovesicular steatosis. Recent gene expression studies indicated that tetracycline treatment affects the expression of many genes associated with fatty acid transport and esterification. In this study, we investigated the role of fatty acid transport and esterification in tetracycline-induced steatosis. Intracellular lipid accumulation and the protein expression of fatty acid translocase (FAT or CD36) and diacylglycerol acyltransferase (DGAT) 2 were increased in both mouse liver and HepG2 cells treated with tetracycline at 50 mg/kg (intraperitoneal injection, i.p.) and 100 μM, respectively. Tetracycline increased the cellular uptake of boron-dipyrromethene-labeled C16 fatty acid, which was abolished by CD36 RNA interference. Oleate-induced cellular lipid accumulation was further enhanced by co-incubation with tetracycline. Tetracycline downregulated extracellular signal-regulated kinase (ERK) phosphorylation, which negatively regulated DGAT2 expression. U0126, a specific ERK inhibitor, also increased DGAT2 expression and cellular lipid accumulation. DGAT1 and 2 knock-down with specific small interfering (si)-RNA completely abrogated the steatogenic effect of tetracycline in HepG2 cells. Taken together, our data showed that tetracycline induces lipid accumulation by facilitating fatty acid transport and triglyceride esterification by upregulating CD36 and DGAT2, respectively.
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Affiliation(s)
- You-Jin Choi
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 151-742, Republic of Korea
| | - Chae-Hyeon Lee
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 151-742, Republic of Korea
| | - Kang-Yo Lee
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 151-742, Republic of Korea
| | - Seung-Hwan Jung
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 151-742, Republic of Korea
| | - Byung-Hoon Lee
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 151-742, Republic of Korea
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20
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Paland N, Gamliel-Lazarovich A, Coleman R, Fuhrman B. Urokinase-type plasminogen activator (uPA) stimulates triglyceride synthesis in Huh7 hepatoma cells via p38-dependent upregulation of DGAT2. Atherosclerosis 2014; 237:200-7. [PMID: 25244504 DOI: 10.1016/j.atherosclerosis.2014.09.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 08/28/2014] [Accepted: 09/01/2014] [Indexed: 01/22/2023]
Abstract
OBJECTIVE The liver is the central organ of fatty acid and triglyceride metabolism. Oxidation and synthesis of fatty acids and triglycerides is under the control of peroxisome-proliferator-activated receptors (PPAR) α. Impairment of these receptors' function contributes to the accumulation of triglycerides in the liver resulting in non-alcoholic fatty liver disease. Urokinase-type plasminogen activator (uPA) was shown to regulate gene expression in the liver involving PPARγ transcriptional activity. In this study we questioned whether uPA modulates triglyceride metabolism in the liver, and investigated the mechanisms involved in the observed processes. METHODS AND RESULTS Huh7 hepatoma cells were incubated with increasing concentrations of uPA for 24 h uPA dose-dependently increased the cellular triglyceride mass, and this effect resulted from increased de novo triglyceride synthesis mediated by the enzyme diglyceride acyltransferase 2 (DGAT2). Also, the amount of free fatty acids was highly up regulated by uPA through activation of the transcription factor SREBP-1. Chemical activation of PPARα further increased uPA-stimulated triglyceride synthesis, whereas inhibition of p38, an upstream activator of PPARα, completely abolished the stimulatory effect of uPA on both triglyceride synthesis and DGAT2 upregulation. The effect of uPA on triglyceride synthesis in Huh7 cells was mediated via binding to its receptor, the uPAR. In vivo studies in uPAR(-/-) mice demonstrated that no lipid droplets were observed in their livers compared to C57BL/6 mice and the triglyceride levels were significantly lower. CONCLUSION This study presents a new biological function of the uPA/uPAR system in the metabolism of triglycerides and might present a new target for an early therapeutic intervention for NAFLD.
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Affiliation(s)
- Nicole Paland
- The Lipid Research Laboratory, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | | | - Raymond Coleman
- Department of Anatomy and Cell Biology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Bianca Fuhrman
- The Lipid Research Laboratory, Technion Faculty of Medicine and Rambam Health Care Campus, Haifa 31096, Israel.
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21
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Choi K, Kim H, Kang H, Lee SY, Lee SJ, Back SH, Lee SH, Kim MS, Lee JE, Park JY, Kim J, Kim S, Song JH, Choi Y, Lee S, Lee HJ, Kim JH, Cho S. Regulation of diacylglycerol acyltransferase 2 protein stability by gp78-associated endoplasmic-reticulum-associated degradation. FEBS J 2014; 281:3048-60. [DOI: 10.1111/febs.12841] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 04/28/2014] [Accepted: 05/09/2014] [Indexed: 12/24/2022]
Affiliation(s)
- Kwangman Choi
- Targeted Medicine Research Center; Korea Research Institute of Bioscience and Biotechnology; Cheongwon Chungbuk Korea
| | - Hyeongki Kim
- Targeted Medicine Research Center; Korea Research Institute of Bioscience and Biotechnology; Cheongwon Chungbuk Korea
- Department of Biomolecular Science; University of Science and Technology; Daejeon Korea
| | - Hyunju Kang
- Targeted Medicine Research Center; Korea Research Institute of Bioscience and Biotechnology; Cheongwon Chungbuk Korea
| | - So-Young Lee
- International Cooperation Office; Ministry of Food and Drug Safety; Cheongwon Chungbuk Korea
| | - Sang Jun Lee
- Infection and Immunity Research Center; Korea Research Institute of Bioscience and Biotechnology; Daejeon Korea
| | - Sung Hoon Back
- School of Biological Sciences; University of Ulsan; Korea
| | - Seo Hyun Lee
- Cancer Cell and Molecular Biology Branch; Research Institute; National Cancer Center; Goyang Korea
| | - M. Sun Kim
- Cancer Cell and Molecular Biology Branch; Research Institute; National Cancer Center; Goyang Korea
| | - Jeong Eun Lee
- Cancer Cell and Molecular Biology Branch; Research Institute; National Cancer Center; Goyang Korea
| | - Ju Young Park
- Cancer Cell and Molecular Biology Branch; Research Institute; National Cancer Center; Goyang Korea
| | - Jiye Kim
- Targeted Medicine Research Center; Korea Research Institute of Bioscience and Biotechnology; Cheongwon Chungbuk Korea
| | - Sunhong Kim
- Targeted Medicine Research Center; Korea Research Institute of Bioscience and Biotechnology; Cheongwon Chungbuk Korea
| | - Jae-Hyung Song
- Targeted Medicine Research Center; Korea Research Institute of Bioscience and Biotechnology; Cheongwon Chungbuk Korea
| | - Yura Choi
- Targeted Medicine Research Center; Korea Research Institute of Bioscience and Biotechnology; Cheongwon Chungbuk Korea
| | - Suui Lee
- Targeted Medicine Research Center; Korea Research Institute of Bioscience and Biotechnology; Cheongwon Chungbuk Korea
| | - Hyun-Jun Lee
- Targeted Medicine Research Center; Korea Research Institute of Bioscience and Biotechnology; Cheongwon Chungbuk Korea
| | - Jong Heon Kim
- Cancer Cell and Molecular Biology Branch; Research Institute; National Cancer Center; Goyang Korea
- Department of System Cancer Science; Graduate School of Cancer Science and Policy; National Cancer Center; Goyang Korea
| | - Sungchan Cho
- Targeted Medicine Research Center; Korea Research Institute of Bioscience and Biotechnology; Cheongwon Chungbuk Korea
- Department of Biomolecular Science; University of Science and Technology; Daejeon Korea
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22
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Chen L, Cui J, Hou J, Long J, Li C, Liu L. A novel negative regulator of adipogenesis: microRNA-363. Stem Cells 2014; 32:510-20. [PMID: 24023010 DOI: 10.1002/stem.1549] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Revised: 05/03/2013] [Accepted: 08/05/2013] [Indexed: 02/05/2023]
Abstract
The differentiation of adipose tissue-derived stromal cells (ADSCs) into adipocytes involves a highly orchestrated series of events that includes cell lineage commitment, mitotic clonal expansion, growth arrest, and terminal differentiation. However, the molecular mechanisms controlling adipogenesis are not yet completely understood. In this study, we investigated whether microRNAs (miRNAs) play a role in adipocyte differentiation. Microarray analysis was performed to determine the miRNA expression profile during ADSC differentiation, and miR-363 was found to be one of the most significantly downregulated miRNAs. We show that the overexpression of miR-363 in ADSCs inhibited mitotic clonal expansion and terminal differentiation. Furthermore, ectopic introduction of miR-363 into ADSCs markedly reduced the levels of E2F3, a key transcription factor that regulates growth and proliferation during mitotic clonal expansion. Finally, using an EGFP/RFP reporter assay, we demonstrate that miR-363 can directly target the 3'UTR of E2F3. Taken together, these results suggest that miR-363 regulates the transition from mitotic clonal expansion to terminal differentiation during adipogenesis in ADSCs, at least in part, by targeting E2F3.
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Affiliation(s)
- Lin Chen
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, People's Republic of China; Department of Oral & Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, People's Republic of China
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23
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Moisá SJ, Shike DW, Faulkner DB, Meteer WT, Keisler D, Loor JJ. Central Role of the PPARγ Gene Network in Coordinating Beef Cattle Intramuscular Adipogenesis in Response to Weaning Age and Nutrition. GENE REGULATION AND SYSTEMS BIOLOGY 2014; 8:17-32. [PMID: 24516329 PMCID: PMC3894150 DOI: 10.4137/grsb.s11782] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 11/14/2013] [Accepted: 11/21/2013] [Indexed: 12/16/2022]
Abstract
Adipogenic/lipogenic transcriptional networks regulating intramuscular fat deposition (IMF) in response to weaning age and dietary starch level were studied. The longissimus muscle (LM) of beef steers on an early weaning (141 days age) plus high-starch diet (EWS) or a normal weaning (NW, 222 days age) plus starch creep-feed diet (CFS) was biopsied at 0 (EW), 25, 50, 96 (NW), 167, and 222 (pre-slaughter) days. Expression patterns of 35 target genes were studied. From NW through slaughter, all steers received the same high-starch diet. In EWS steers the expression of PPARG, other adipogenic (CEBPA, ZFP423) and lipogenic (THRSP, SREBF1, INSIG1) activators, and several enzymes (FASN, SCD, ELOVL6, PCK1, DGAT2) that participate in the process of IMF increased gradually to a peak between 96 and 167 days on treatment. Steers in NW did not achieve similar expression levels even by 222 days on treatment, suggesting a blunted response even when fed a high-starch diet after weaning. High-starch feeding at an early age (EWS) triggers precocious and sustained adipogenesis, resulting in greater marbling.
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Affiliation(s)
- Sonia J Moisá
- Mammalian NutriPhysioGenomics, Department of Animal Sciences, University of Illinois, Urbana, Illinois, USA
| | - Daniel W Shike
- Department of Animal Sciences, University of Illinois, Urbana, Illinois, USA
| | - Dan B Faulkner
- Department of Animal Science, University of Arizona, Tucson, Arizona, USA
| | - William T Meteer
- Department of Animal Sciences, University of Illinois, Urbana, Illinois, USA
| | - Duane Keisler
- Department of Animal Science, University of Missouri, Columbia, Missouri, USA
| | - Juan J Loor
- Mammalian NutriPhysioGenomics, Department of Animal Sciences, University of Illinois, Urbana, Illinois, USA. ; Department of Animal Sciences, University of Illinois, Urbana, Illinois, USA. ; Division of Nutritional Sciences, Illinois Informatics Institute, University of Illinois, Urbana, Illinois, USA
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24
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Esteves CL, Kelly V, Breton A, Taylor AI, West CC, Donadeu FX, Péault B, Seckl JR, Chapman KE. Proinflammatory cytokine induction of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) in human adipocytes is mediated by MEK, C/EBPβ, and NF-κB/RelA. J Clin Endocrinol Metab 2014; 99:E160-8. [PMID: 24243637 DOI: 10.1210/jc.2013-1708] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
CONTEXT Levels of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), which regenerates active glucocorticoids, are selectively elevated in adipose tissue in human obesity and metabolic syndrome, both conditions associated with chronic low-grade inflammation. 11β-HSD1 expression is induced by proinflammatory cytokines in a variety of cell types, including in human adipocytes differentiated in vitro. OBJECTIVE Our objective was to determine the mechanisms by which proinflammatory cytokines induce 11β-HSD1 in human adipocytes. RESULTS The proinflammatory cytokines IL-1α (10 ng/mL) and TNFα (20 ng/mL) increased 11β-HSD1 mRNA levels in human primary adipocyte fractions and Simpson-Golabi-Behmel syndrome (SGBS) adipocytes (P<.001). Inhibition of the MAPK/ERK kinase (MEK) attenuated CCAAT/enhancer binding protein (C/EBP) β phosphorylation at Thr235 and IL-1α/TNFα induction of 11β-HSD1 (P≤.007). The small interfering RNA-mediated knockdown of C/EBPβ and nuclear factor (NF)-κB/RelA or inhibition of NF-κB/RelA also attenuated cytokine induction of 11β-HSD1 (P≤.001). Moreover, induction of 11β-HSD1 by IL-1α in SGBS cells was associated with nuclear localization of C/EBPβ and NF-κB/RelA. Chromatin immunoprecipitation experiments showed C/EBPβ and NF-κB/RelA located to the 11β-HSD1 promoter in human adipose tissue. Treatment of adipocyte fractions or SGBS adipocytes with metformin or acetylsalicylic acid, which target C/EBPβ and NF-κB/RelA signaling, attenuated the IL-1α induction of 11β-HSD1 (P≤.002). CONCLUSIONS Increased proinflammatory signaling in inflamed adipose tissue may mediate elevated 11β-HSD1 expression at this site via MEK, C/EBPβ, and NF-κB/RelA. These molecules/signaling pathways are, therefore, potential targets for drugs, including metformin and acetylsalicylic acid, to prevent/decreased up-regulation of 11β-HSD1 in human obese/metabolic syndrome adipose tissue.
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Affiliation(s)
- Cristina L Esteves
- Endocrinology Unit, University/British Heart Foundation Centre for Cardiovascular Science (C.L.E., V.K., A.I.T., C.C.W., B.P., J.R.S., K.E.C.), Centre for Regenerative Medicine (C.C.W., B.P.), The University of Edinburgh, Edinburgh EH16 4TJ, United Kingdom; and Division of Developmental Biology (A.B., F.X.D.), The Roslin Institute, EH25 9RG, United Kingdom
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25
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Chapman K, Holmes M, Seckl J. 11β-hydroxysteroid dehydrogenases: intracellular gate-keepers of tissue glucocorticoid action. Physiol Rev 2013; 93:1139-206. [PMID: 23899562 DOI: 10.1152/physrev.00020.2012] [Citation(s) in RCA: 542] [Impact Index Per Article: 49.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Glucocorticoid action on target tissues is determined by the density of "nuclear" receptors and intracellular metabolism by the two isozymes of 11β-hydroxysteroid dehydrogenase (11β-HSD) which catalyze interconversion of active cortisol and corticosterone with inert cortisone and 11-dehydrocorticosterone. 11β-HSD type 1, a predominant reductase in most intact cells, catalyzes the regeneration of active glucocorticoids, thus amplifying cellular action. 11β-HSD1 is widely expressed in liver, adipose tissue, muscle, pancreatic islets, adult brain, inflammatory cells, and gonads. 11β-HSD1 is selectively elevated in adipose tissue in obesity where it contributes to metabolic complications. Similarly, 11β-HSD1 is elevated in the ageing brain where it exacerbates glucocorticoid-associated cognitive decline. Deficiency or selective inhibition of 11β-HSD1 improves multiple metabolic syndrome parameters in rodent models and human clinical trials and similarly improves cognitive function with ageing. The efficacy of inhibitors in human therapy remains unclear. 11β-HSD2 is a high-affinity dehydrogenase that inactivates glucocorticoids. In the distal nephron, 11β-HSD2 ensures that only aldosterone is an agonist at mineralocorticoid receptors (MR). 11β-HSD2 inhibition or genetic deficiency causes apparent mineralocorticoid excess and hypertension due to inappropriate glucocorticoid activation of renal MR. The placenta and fetus also highly express 11β-HSD2 which, by inactivating glucocorticoids, prevents premature maturation of fetal tissues and consequent developmental "programming." The role of 11β-HSD2 as a marker of programming is being explored. The 11β-HSDs thus illuminate the emerging biology of intracrine control, afford important insights into human pathogenesis, and offer new tissue-restricted therapeutic avenues.
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Affiliation(s)
- Karen Chapman
- Endocrinology Unit, Centre for Cardiovascular Science, The Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom
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26
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Chapman KE, Coutinho AE, Zhang Z, Kipari T, Savill JS, Seckl JR. Changing glucocorticoid action: 11β-hydroxysteroid dehydrogenase type 1 in acute and chronic inflammation. J Steroid Biochem Mol Biol 2013; 137:82-92. [PMID: 23435016 PMCID: PMC3925798 DOI: 10.1016/j.jsbmb.2013.02.002] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 01/22/2013] [Accepted: 02/04/2013] [Indexed: 12/18/2022]
Abstract
Since the discovery of cortisone in the 1940s and its early success in treatment of rheumatoid arthritis, glucocorticoids have remained the mainstay of anti-inflammatory therapies. However, cortisone itself is intrinsically inert. To be effective, it requires conversion to cortisol, the active glucocorticoid, by the enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). Despite the identification of 11β-HSD in liver in 1953 (which we now know to be 11β-HSD1), its physiological role has been little explored until recently. Over the past decade, however, it has become apparent that 11β-HSD1 plays an important role in shaping endogenous glucocorticoid action. Acute inflammation is more severe with 11β-HSD1-deficiency or inhibition, yet in some inflammatory settings such as obesity or diabetes, 11β-HSD1-deficiency/inhibition is beneficial, reducing inflammation. Current evidence suggests both beneficial and detrimental effects may result from 11β-HSD1 inhibition in chronic inflammatory disease. Here we review recent evidence pertaining to the role of 11β-HSD1 in inflammation. This article is part of a Special Issue entitled 'CSR 2013'.
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Affiliation(s)
- Karen E Chapman
- University/BHF Centre for Cardiovascular Sciences, The Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4TJ, UK.
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Chen L, Song J, Cui J, Hou J, Zheng X, Li C, Liu L. microRNAs regulate adipocyte differentiation. Cell Biol Int 2013; 37:533-46. [PMID: 23504919 DOI: 10.1002/cbin.10063] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Accepted: 01/22/2013] [Indexed: 02/05/2023]
Abstract
The number of adipocytes is relevant to the extent of differentiation from pluripotent stem cells into pre-adipocytes, whereas the size of adipocytes relates to the extent of differentiation from pre-adipocytes into mature fat cells and the accumulation of triglyceride. Investigation of the molecular regulatory mechanism of adipocyte differentiation is not only essential for understanding the physiological processes of adipogenesis, but it is also important for identifying new biomarkers and therapeutic targets for some metabolic diseases, such as obesity and diabetes. microRNAs (miRNAs) appear to play important roles in adipocyte differentiation. During adipogenesis, miRNAs can accelerate or inhibit adipocyte differentiation by acting on transcription factors, regulating signalling pathways related to adipogenesis, or blocking the mitotic clonal expansion stage, thus regulating adipocyte development. The regulatory role of some miRNAs varies in different species or different cells. In this review, the biological characteristics of miRNA and the adipocyte differentiation process are concisely discussed. Recent advances in our understanding of the role of miRNAs in adipocytes development or adipogenesis are discussed.
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Affiliation(s)
- Lin Chen
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China
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28
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Hepatic triacylglycerol synthesis and secretion: DGAT2 as the link between glycaemia and triglyceridaemia. Biochem J 2013; 451:1-12. [PMID: 23489367 DOI: 10.1042/bj20121689] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
lThe liver regulates both glycaemia and triglyceridaemia. Hyperglycaemia and hypertriglyceridaemia are both characteristic of (pre)diabetes. Recent observations on the specialised role of DGAT2 (diacylglycerol acyltransferase 2) in catalysing the de novo synthesis of triacylglycerols from newly synthesized fatty acids and nascent diacylglycerols identifies this enzyme as the link between the two. This places DGAT2 at the centre of carbohydrate-induced hypertriglyceridaemia and hepatic steatosis. This function is complemented, but not substituted for, by the ability of DGAT1 to rescue partial glycerides from complete hydrolysis. In peripheral tissues not normally considered to be lipogenic, synthesis of triacylglycerols may largely bypass DGAT2 except in hyperglycaemic/hyperinsulinaemic conditions, when induction of de novo fatty acid synthesis in these tissues may contribute towards increased triacylglycerol secretion (intestine) or insulin resistance (adipose tissue, and cardiac and skeletal muscle).
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29
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Yi F, Yang F, Liu X, Chen H, Ji T, Jiang L, Wang X, Yang Z, Zhang LH, Ding X, Liang Z, Du Q. RNA-seq identified a super-long intergenic transcript functioning in adipogenesis. RNA Biol 2013; 10:991-1001. [PMID: 23603976 PMCID: PMC4111738 DOI: 10.4161/rna.24644] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
RNA transcripts are generally classified into polyA-plus and polyA-minus subgroups due to the presence or absence of a polyA tail at the 3′ end. Even though a number of physiologically and pathologically important polyA-minus RNAs have been recently identified, a systematic analysis of the expression and function of these transcripts in adipogenesis is still elusive. To study the potential function of the polyA-minus RNAs in adipogenesis, a dynamic expressional profiling was performed in the induced differentiation of 3T3-L1 cells. In addition to identifying thousands of novel intergenic transcripts, differentiation-synchronized expression was characterized for many of them. Among these, several large intergenic transcripts were found to be upregulated by more than 19-fold during differentiation. Further study demonstrated a fat tissue-specific expression pattern for these regions and identified an adipogenesis-associated long non-coding RNA. Collectively, these lines of evidence contribute to the characterization of a super-long intergenic transcript functioning in adipogenesis.
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Affiliation(s)
- Fan Yi
- Laboratory of Nucleic Acid Technology and Laboratory of State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, School of Pharmaceutical Sciences, Peking University, Beijing, China
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30
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Shao HY, Hsu HY, Wu KS, Hee SW, Chuang LM, Yeh JI. Prolonged induction activates Cebpα independent adipogenesis in NIH/3T3 cells. PLoS One 2013; 8:e51459. [PMID: 23326314 PMCID: PMC3542373 DOI: 10.1371/journal.pone.0051459] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Accepted: 11/07/2012] [Indexed: 11/25/2022] Open
Abstract
Background 3T3-L1 cells are widely used to study adipogenesis and insulin response. Their adipogenic potential decreases with time in the culture. Expressing exogenous genes in 3T3-L1 cells can be challenging. This work tries to establish and characterize an alternative model of cultured adipocytes that is easier to work with than the 3T3-L1 cells. Methodology/Principal Findings Induced cells were identified as adipocytes based on the following three characteristics: (1) Accumulation of triglyceride droplets as demonstrated by oil red O stain. (2) Transport rate of 2-deoxyglucose increased after insulin stimulation. (3) Expression of fat specific genes such as Fabp4 (aP2), Slc2a4 (Glut4) and Pparg (PPARγ). Among the cell lines induced under different conditions in this study, only NIH/3T3 cells differentiated into adipocytes after prolonged incubation in 3T3-L1 induction medium containing 20% instead of 10% fetal bovine serum. Rosiglitazone added to the induction medium shortened the incubation period from 14 to 7 days. The PI3K/AKT pathway showed similar changes upon insulin stimulation in these two adipocytes. C/EBPα mRNA was barely detectable in NIH/3T3 adipocytes. NIH/3T3 adipocytes induced in the presence of rosiglitazone showed higher 2-deoxyglucose transport rate after insulin stimulation, expressed less Agt (angiotensinogen) and more PPARγ. Knockdown of C/EBPα using shRNA blocked 3T3-L1 but not NIH/3T3 cell differentiation. Mouse adipose tissues from various anatomical locations showed comparable levels of C/EBPα mRNA. Conclusions/Significance NIH/3T3 cells were capable of differentiating into adipocytes without genetic engineering. They were an adipocyte model that did not require the reciprocal activation between C/EBPα and PPARγ to differentiate. Future studies in the C/EBPα independent pathways leading to insulin responsiveness may reveal new targets to diabetes treatment.
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Affiliation(s)
- Hsiao-Yun Shao
- Graduate Institute of Molecular and Cell Biology, Tzu Chi University, Hualien, Taiwan
| | - Hsue-Yin Hsu
- Department and Graduate Institute of Life Sciences, Tzu Chi University, Hualien, Taiwan
| | - Kuan-Sju Wu
- Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan
| | - Siow-Wey Hee
- Institute of Molecular Medicine, National Taiwan University, Taipei, Taiwan
| | - Lee-Ming Chuang
- Institute of Molecular Medicine, National Taiwan University, Taipei, Taiwan
| | - Jih-I Yeh
- Graduate Institute of Molecular and Cell Biology, Tzu Chi University, Hualien, Taiwan
- Department of Family Medicine, Tzu Chi University, Hualien, Taiwan
- Department of Family Medicine, Buddhist Tzu Chi General Hospital, Hualien, Taiwan
- * E-mail:
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31
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Esteves CL, Kelly V, Bégay V, Lillico SG, Leutz A, Seckl JR, Chapman KE. Stable conditional expression and effect of C/ebpβ-LIP in adipocytes using the pSLIK system. J Mol Endocrinol 2013; 51:91-8. [PMID: 23620165 PMCID: PMC3672996 DOI: 10.1530/jme-13-0029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Murine 3T3-L1 adipocytes are widely used as a cellular model of obesity. However, whereas transfection of 3T3-L1 preadipocytes is straightforward, ectopic gene expression in mature 3T3-L1 adipocytes has proved challenging. Here, we used the pSLIK vector system to generate stable doxycycline-inducible expression of the liver-enriched inhibitor protein isoform of CCAAT/enhancer binding protein β (C/ebpβ (Cebpb)) (C/EBPβ-LIP) in fully differentiated 3T3-L1 adipocytes. Because overexpression of C/ebpβ-LIP impairs adipocyte differentiation, the C/ebpβ-LIP construct was first integrated in 3T3-L1 preadipocytes but expression was induced only when adipocytes were fully differentiated. Increased C/EBPβ-LIP in mature adipocytes down-regulated C/ebpβ target genes including 11β-hydroxysteroid dehydrogenase type 1, phosphoenolpyruvate carboxykinase and fatty acid binding protein 4 but had no effect on asparagine synthetase, demonstrating that transcriptional down-regulation by C/ebpβ-LIP in 3T3-L1 adipocytes is not a general effect. Importantly, these genes were modulated in a similar manner in adipose tissue of mice with genetically increased C/ebpβ-LIP levels. The use of the pSLIK system to conditionally express transgenes in 3T3-L1 cells could be a valuable tool to dissect adipocyte physiology.
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Affiliation(s)
- Cristina L Esteves
- Endocrinology Unit, Queen's Medical Research Institute, University/BHF Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, UK.
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Role of C/EBPβ-LAP and C/EBPβ-LIP in early adipogenic differentiation of human white adipose-derived progenitors and at later stages in immature adipocytes. Differentiation 2013; 85:20-31. [DOI: 10.1016/j.diff.2012.11.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 09/20/2012] [Accepted: 11/26/2012] [Indexed: 12/20/2022]
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The human lipodystrophy protein seipin is an ER membrane adaptor for the adipogenic PA phosphatase lipin 1. Mol Metab 2012; 2:38-46. [PMID: 24024128 DOI: 10.1016/j.molmet.2012.11.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Revised: 11/23/2012] [Accepted: 11/29/2012] [Indexed: 11/22/2022] Open
Abstract
Disruption of the gene BSCL2 causes a severe, generalised lipodystrophy, demonstrating the critical role of its protein product, seipin, in human adipose tissue development. Seipin is essential for adipocyte differentiation, whilst the study of seipin in non-adipose cells has suggested a role in lipid droplet formation. However, its precise molecular function remains poorly understood. Here we demonstrate that seipin can inducibly bind lipin 1, a phosphatidic acid (PA) phosphatase important for lipid synthesis and adipogenesis. Knockdown of seipin during early adipogenesis decreases the association of lipin 1 with membranes and increases the accumulation of its substrate PA. Conversely, PA levels are reduced in differentiating cells by overexpression of wild-type seipin but not by expression of a mutated seipin that is unable to bind lipin 1. Together our data identify lipin as the first example of a seipin-interacting protein and reveals a novel molecular function for seipin in developing adipocytes.
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Esteves CL, Kelly V, Bégay V, Man TY, Morton NM, Leutz A, Seckl JR, Chapman KE. Regulation of adipocyte 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) by CCAAT/enhancer-binding protein (C/EBP) β isoforms, LIP and LAP. PLoS One 2012; 7:e37953. [PMID: 22662254 PMCID: PMC3360670 DOI: 10.1371/journal.pone.0037953] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 04/30/2012] [Indexed: 12/11/2022] Open
Abstract
11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) catalyses intracellular regeneration of active glucocorticoids, notably in liver and adipose tissue. 11β-HSD1 is increased selectively in adipose tissue in human obesity, a change implicated in the pathogenesis of metabolic syndrome. With high fat (HF)-feeding, adipose tissue 11β-HSD1 is down-regulated in mice, plausibly to counteract metabolic disease. Transcription of 11β-HSD1 is directly regulated by members of the CCAAT/enhancer binding protein (C/EBP) family. Here we show that while total C/EBPβ in adipose tissue is unaltered by HF diet, the ratio of the C/EBPβ isoforms liver-enriched inhibitor protein (LIP) and liver-enriched activator protein (LAP) (C/EBPβ-LIP:LAP) is increased in subcutaneous adipose. This may cause changes in 11β-HSD1 expression since genetically modified C/EBPβ(+/L) mice, with increased C/EBPβ-LIP:LAP ratio, have decreased subcutaneous adipose 11β-HSD1 mRNA levels, whereas C/EBPβΔuORF mice, with decreased C/EBPβ-LIP:LAP ratio, show increased subcutaneous adipose 11β-HSD1. C/EBPβ-LIP:LAP ratio is regulated by endoplasmic reticulum (ER) stress and mTOR signalling, both of which are altered in obesity. In 3T3-L1 adipocytes, 11β-HSD1 mRNA levels were down-regulated following induction of ER stress by tunicamycin but were up-regulated following inhibition of mTOR by rapamycin. These data point to a central role for C/EBPβ and its processing to LIP and LAP in transcriptional regulation of 11β-HSD1 in adipose tissue. Down-regulation of 11β-HSD1 by increased C/EBPβ-LIP:LAP in adipocytes may be part of a nutrient-sensing mechanism counteracting nutritional stress generated by HF diet.
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Affiliation(s)
- Cristina L. Esteves
- Endocrinology Unit, University/BHF Centre for Cardiovascular Science, Queen’s Medical Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
| | - Val Kelly
- Endocrinology Unit, University/BHF Centre for Cardiovascular Science, Queen’s Medical Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
| | - Valérie Bégay
- Max Delbrüeck Center for Molecular Medicine, Berlin, Germany
| | - Tak Y. Man
- Endocrinology Unit, University/BHF Centre for Cardiovascular Science, Queen’s Medical Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
| | - Nicholas M. Morton
- Molecular Metabolism Group, University/BHF Centre for Cardiovascular Science, Queen’s Medical Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
| | - Achim Leutz
- Max Delbrüeck Center for Molecular Medicine, Berlin, Germany
| | - Jonathan R. Seckl
- Endocrinology Unit, University/BHF Centre for Cardiovascular Science, Queen’s Medical Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
| | - Karen E. Chapman
- Endocrinology Unit, University/BHF Centre for Cardiovascular Science, Queen’s Medical Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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Hollis A, Sperl B, Gräber M, Berg T. The Natural Product Betulinic Acid Inhibits C/EBP Family Transcription Factors. Chembiochem 2011; 13:302-7. [DOI: 10.1002/cbic.201100652] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Indexed: 12/19/2022]
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36
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Coleman RA, Mashek DG. Mammalian triacylglycerol metabolism: synthesis, lipolysis, and signaling. Chem Rev 2011; 111:6359-86. [PMID: 21627334 PMCID: PMC3181269 DOI: 10.1021/cr100404w] [Citation(s) in RCA: 205] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Rosalind A Coleman
- Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
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Santangelo C, Varì R, Scazzocchio B, Filesi C, D'Archivio M, Giovannini C, Masella R. CCAAT/enhancer-binding protein-β participates in oxidized LDL-enhanced proliferation in 3T3-L1 cells. Biochimie 2011; 93:1510-9. [PMID: 21621583 DOI: 10.1016/j.biochi.2011.05.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 05/10/2011] [Indexed: 01/10/2023]
Abstract
Increased circulating oxidized LDL (oxLDL) have been found in obese subjects. Obesity is characterized by an excess of fat mass resulting from an increase in adipocyte number and size. The generation of new adipocytes is a tightly controlled process where multiple factors acting in a signaling cascade follow a precise temporal expression pattern; oxLDL appear to have a role in the impairment of this process. The purpose of this study was to examine the effects of oxLDL on the mechanisms involved in the proliferative stage of the differentiation process in 3T3-L1 cells. After hormonal induction, 3T3-L1 cells undergo approximately two rounds of mitotic clonal expansion (MCE), a process required for adipogenesis. CCAAT/enhancer-binding protein β (C/EBPβ) is immediately expressed after induction, and plays a crucial role in MCE, but its expression must decrease to allow preadipocytes to mature into adipocytes. We found that, in the presence of stimuli to differentiate, oxLDL induced a higher proliferation rate in this cell line, associated with a sustained up-regulation of C/EBPβ, which remained activated inside the nucleus for several days. RNAi-mediated knockdown of C/EBPβ 24 h after oxLDL treatment counteracted the increase in proliferation rate. Both C/EBPβ expression and proliferation processes appear to be influenced by cAMP/protein kinase A (PKA) and extracellular signal-regulated kinases1/2 (ERK1/2) pathways. OxLDL treatment led to increased levels of cAMP, and to a strong, prolonged phosphorylation of ERK1/2 and C/EBPβ. The addition of cAMP and PKA inhibitors, SQ22536 and H-89, respectively, reduced proliferation only in oxLDL-treated cells, whereas the addition of ERK1/2 inhibitor U0126 blocked proliferation in both control and oxLDL-treated cells. C/EBPβ nuclear expression and DNA-binding activity were reduced by U0126, under all tested conditions. These findings show that the altered expression pattern of C/EBPβ is involved in the increase in the number of proliferating cells induced by oxLDL, in hormone-stimulated 3T3-L1 cells.
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Affiliation(s)
- Carmela Santangelo
- Department of Veterinary Public Health and Food Safety, Italian National Institute of Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
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Coutinho AE, Chapman KE. The anti-inflammatory and immunosuppressive effects of glucocorticoids, recent developments and mechanistic insights. Mol Cell Endocrinol 2011; 335:2-13. [PMID: 20398732 PMCID: PMC3047790 DOI: 10.1016/j.mce.2010.04.005] [Citation(s) in RCA: 1070] [Impact Index Per Article: 82.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 04/02/2010] [Accepted: 04/06/2010] [Indexed: 02/08/2023]
Abstract
Since the discovery of glucocorticoids in the 1940s and the recognition of their anti-inflammatory effects, they have been amongst the most widely used and effective treatments to control inflammatory and autoimmune diseases. However, their clinical efficacy is compromised by the metabolic effects of long-term treatment, which include osteoporosis, hypertension, dyslipidaemia and insulin resistance/type 2 diabetes mellitus. In recent years, a great deal of effort has been invested in identifying compounds that separate the beneficial anti-inflammatory effects from the adverse metabolic effects of glucocorticoids, with limited effect. It is clear that for these efforts to be effective, a greater understanding is required of the mechanisms by which glucocorticoids exert their anti-inflammatory and immunosuppressive actions. Recent research is shedding new light on some of these mechanisms and has produced some surprising new findings. Some of these recent developments are reviewed here.
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Affiliation(s)
| | - Karen E. Chapman
- Corresponding author. Tel.: +44 131 242 6736; fax: +44 131 242 6779.
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C/EBP alpha expression is associated with homeostasis of the gastric epithelium and with gastric carcinogenesis. J Transl Med 2010; 90:1132-9. [PMID: 20386538 DOI: 10.1038/labinvest.2010.79] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Transcription factors from the CCAAT/enhancer-binding protein (C/EBP) family are fundamental for the control of differentiation and proliferation of many adult tissues. C/EBP alpha has a crucial role in inducing terminal differentiation and is an established tumor suppressor gene in several cancer models. The objective of this study was to analyze the putative role of C/EBP alpha in gastric carcinoma (GC). We analyzed the expression of C/EBP alpha in normal and neoplastic gastric tissues, and assessed the role of C/EBP alpha on proliferation and differentiation of GC cells. In normal gastric mucosa, C/EBP alpha is expressed in the foveolar epithelium and co-localizes with the gastric differentiation marker trefoil factor 1 (TFF1). The expression of C/EBP alpha was found to be lost in 30% of GC cases. To evaluate the role of C/EBP alpha in cell proliferation and differentiation, we transfected GC cells with a full-length C/EBP alpha protein. We observed a significant decrease in proliferation in C/EBP alpha-transfected cells. This was accompanied by a decrease in Cyclin D1, an increase in P27 expression, and an increased expression of TFF1. Finally, we showed that inhibition of the Ras/MAPK pathway leads to increased C/EBP alpha and TFF1 expression, and decreased cell proliferation and cyclin D1 expression in GC cells. Our results suggest that C/EBP alpha (together with other members of the C/EBP family) has an active role in the control of differentiation and proliferation in normal gastric mucosa. In GC, loss of C/EBP alpha may be associated with the switch from a cellular differentiation to a cellular proliferation program, presumably as a consequence of Ras/MAPK pathway activation.
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40
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PAYNE VA, AU WS, LOWE CE, RAHMAN SM, FRIEDMAN JE, O’RAHILLY S, ROCHFORD JJ. C/EBP transcription factors regulate SREBP1c gene expression during adipogenesis. Biochem J 2009; 425:215-23. [PMID: 19811452 PMCID: PMC2913385 DOI: 10.1042/bj20091112] [Citation(s) in RCA: 140] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The transcription factor SREBP1c (sterol-regulatory-element-binding protein 1c) is highly expressed in adipose tissue and plays a central role in several aspects of adipocyte development including the induction of PPARgamma (peroxisome-proliferator-activated receptor gamma), the generation of an endogenous PPARgamma ligand and the expression of several genes critical for lipid biosynthesis. Despite its significance, the regulation of SREBP1c expression during adipogenesis is not well characterized. We have noted that in several models of adipogenesis, SREBP1c expression closely mimics that of known C/EBPbeta (CCAAT/enhancer-binding protein beta) targets. Inhibition of C/EBP activity during adipogenesis by expressing either the dominant-negative C/EBPbeta LIP (liver-enriched inhibitory protein) isoform, the co-repressor ETO (eight-twenty one/MTG8) or using siRNAs (small interfering RNAs) targeting either C/EBPbeta or C/EBPdelta significantly impaired early SREBP1c induction. Furthermore, ChIP (chromatin immunoprecipitation) assays identified specific sequences in the SREBP1c promoter to which C/EBPbeta and C/EBPdelta bind in intact cells, demonstrating that these factors may directly regulate SREBP1c expression. Using cells in which C/EBPalpha expression is inhibited using shRNA (short hairpin RNA) and ChIP assays we show that C/EBPalpha replaces C/EBPbeta and C/EBPdelta as a regulator of SREBP1c expression in maturing adipocytes. These results provide novel insight into the induction of SREBP1c expression during adipogenesis. Moreover, the findings of the present study identify an important additional mechanism via which the C/EBP transcription factors may control a network of gene expression regulating adipogenesis, lipogenesis and insulin sensitivity.
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Affiliation(s)
- Victoria A. PAYNE
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 0QQ, U.K
| | - Wo-Shing AU
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 0QQ, U.K
| | - Christopher E. LOWE
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 0QQ, U.K
| | - Shaikh M. RAHMAN
- Department of Pediatrics, University of Colorado Health Sciences Center, Denver, CO 80262, U.S.A
| | - Jacob E. FRIEDMAN
- Department of Pediatrics, University of Colorado Health Sciences Center, Denver, CO 80262, U.S.A
| | - Stephen O’RAHILLY
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 0QQ, U.K
| | - Justin J. ROCHFORD
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 0QQ, U.K
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Abstract
The storage of fatty acids and fatty alcohols in the form of neutral lipids such as triacylglycerol (TAG), cholesteryl ester (CE), and wax ester (WE) serves to provide reservoirs for membrane formation and maintenance, lipoprotein trafficking, lipid detoxification, evaporation barriers, and fuel in times of stress or nutrient deprivation. This ancient process likely originated in actinomycetes and has persisted in eukaryotes, albeit by different molecular mechanisms. A surfeit of neutral lipids is strongly, perhaps causally, related to several human diseases such as diabetes mellitus, obesity, atherosclerosis and nonalcoholic fatty liver disease. Therefore, understanding the metabolic pathways of neutral lipid synthesis and the roles of the enzymes involved may facilitate the development of new therapeutic interventions for these syndromes.
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Affiliation(s)
- Aaron R Turkish
- Department of Pediatrics, Columbia University Medical Center, 630 W. 168th St., New York, NY, USA.
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Prokesch A, Hackl H, Hakim-Weber R, Bornstein SR, Trajanoski Z. Novel insights into adipogenesis from omics data. Curr Med Chem 2009; 16:2952-64. [PMID: 19689276 PMCID: PMC2765082 DOI: 10.2174/092986709788803132] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2009] [Revised: 05/15/2009] [Accepted: 05/16/2009] [Indexed: 01/05/2023]
Abstract
Obesity, the excess accumulation of adipose tissue, is one of the most pressing health problems in both the Western world and in developing countries. Adipose tissue growth results from two processes: the increase in number of adipocytes (hyperplasia) that develop from precursor cells, and the growth of individual fat cells (hypertrophy) due to incorporation of triglycerides. Adipogenesis, the process of fat cell development, has been extensively studied using various cell and animal models. While these studies pointed out a number of key factors involved in adipogenesis, the list of molecular components is far from complete. The advance of high-throughput technologies has sparked many experimental studies aimed at the identification of novel molecular components regulating adipogenesis. This paper examines the results of recent studies on adipogenesis using high-throughput technologies. Specifically, it provides an overview of studies employing microarrays for gene expression profiling and studies using gel based and non-gel based proteomics as well as a chromatin immunoprecipitation followed by microarray analysis (ChIP-chip) or sequencing (ChIP-seq). Due to the maturity of the technology, the bulk of the available data was generated using microarrays. Therefore these data sets were not only reviewed but also underwent meta analysis. The review also shows that large-scale omics technologies in conjunction with sophisticated bioinformatics analyses can provide not only a list of novel players, but also a global view on biological processes and molecular networks. Finally, developing technologies and computational challenges associated with the data analyses are highlighted, and an outlook on the questions not previously addressed is provided.
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Affiliation(s)
- Andreas Prokesch
- Institute for Genomics and Bioinformatics, Graz University of Technology, Graz, Austria
| | - Hubert Hackl
- Institute for Genomics and Bioinformatics, Graz University of Technology, Graz, Austria
| | - Robab Hakim-Weber
- Department of Internal Medicine, Technical University Dresden, Dresden, Germany
| | - Stefan R Bornstein
- Department of Internal Medicine, Technical University Dresden, Dresden, Germany
| | - Zlatko Trajanoski
- Institute for Genomics and Bioinformatics, Graz University of Technology, Graz, Austria
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Yen CLE, Stone SJ, Koliwad S, Harris C, Farese RV. Thematic review series: glycerolipids. DGAT enzymes and triacylglycerol biosynthesis. J Lipid Res 2008; 49:2283-301. [PMID: 18757836 PMCID: PMC3837458 DOI: 10.1194/jlr.r800018-jlr200] [Citation(s) in RCA: 759] [Impact Index Per Article: 47.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Revised: 08/29/2008] [Indexed: 12/18/2022] Open
Abstract
Triacylglycerols (triglycerides) (TGs) are the major storage molecules of metabolic energy and FAs in most living organisms. Excessive accumulation of TGs, however, is associated with human diseases, such as obesity, diabetes mellitus, and steatohepatitis. The final and the only committed step in the biosynthesis of TGs is catalyzed by acyl-CoA:diacylglycerol acyltransferase (DGAT) enzymes. The genes encoding two DGAT enzymes, DGAT1 and DGAT2, were identified in the past decade, and the use of molecular tools, including mice deficient in either enzyme, has shed light on their functions. Although DGAT enzymes are involved in TG synthesis, they have distinct protein sequences and differ in their biochemical, cellular, and physiological functions. Both enzymes may be useful as therapeutic targets for diseases. Here we review the current knowledge of DGAT enzymes, focusing on new advances since the cloning of their genes, including possible roles in human health and diseases.
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Affiliation(s)
- Chi-Liang Eric Yen
- Department of Nutritional Sciences, University of Wisconsin, Madison, WI
53706
| | - Scot J. Stone
- Department of Biochemistry, University of Saskatchewan, Saskatoon,
Saskatchewan, Canada
| | - Suneil Koliwad
- Gladstone Institute of Cardiovascular Disease, University of California, San
Francisco, San Francisco, CA 94141
- Cardiovascular Research Institute, University of California, San
Francisco, San Francisco, CA 94141
- Department of Medicine, University of California, San Francisco,
San Francisco, CA 94141
| | - Charles Harris
- Gladstone Institute of Cardiovascular Disease, University of California, San
Francisco, San Francisco, CA 94141
- Cardiovascular Research Institute, University of California, San
Francisco, San Francisco, CA 94141
- Department of Medicine, University of California, San Francisco,
San Francisco, CA 94141
| | - Robert V. Farese
- Gladstone Institute of Cardiovascular Disease, University of California, San
Francisco, San Francisco, CA 94141
- Cardiovascular Research Institute, University of California, San
Francisco, San Francisco, CA 94141
- Department of Medicine, University of California, San Francisco,
San Francisco, CA 94141
- Department of Biochemistry and Biophysics, University of
California, San Francisco, San Francisco, CA 94141
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Payne VA, Grimsey N, Tuthill A, Virtue S, Gray SL, Dalla Nora E, Semple RK, O'Rahilly S, Rochford JJ. The human lipodystrophy gene BSCL2/seipin may be essential for normal adipocyte differentiation. Diabetes 2008; 57:2055-60. [PMID: 18458148 PMCID: PMC2494687 DOI: 10.2337/db08-0184] [Citation(s) in RCA: 160] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2008] [Accepted: 04/28/2008] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Berardinelli-Seip congenital lipodystrophy type 2 (BSCL2) is a recessive disorder featuring near complete absence of adipose tissue. Remarkably, although the causative gene, BSCL2, has been known for several years, its molecular function and its role in adipose tissue development have not been elucidated. Therefore, we examined whether BSCL2 is involved in the regulation of adipocyte differentiation and the mechanism whereby pathogenic mutations in BSCL2 cause lipodystrophy. RESEARCH DESIGN AND METHODS Following the characterization of BSCL2 expression in developing adipocytes, C3H10T1/2 mesenchymal stem cells were generated in which BSCL2 expression was knocked down using short hairpin RNA (shRNA). These cells were used to investigate whether BSCL2 is required for adipogenesis. BSCL2 constructs harboring pathogenic mutations known to cause lipodystrophy were also generated and characterized. RESULTS BSCL2 expression was strongly induced during adipocyte differentiation, and the induction of BSCL2 expression was essential for adipogenesis to occur. The initial induction of key adipogenic transcription factors, including peroxisome proliferator-activated receptor (PPAR)gamma and CAAT/enhancer-binding protein-alpha, was preserved in cells lacking BSCL2. However, the expression of these critical factors was not sustained, suggesting that the activity of PPARgamma was impaired. Moreover, expression of key genes mediating triglyceride synthesis, including AGPAT2, lipin 1, and DGAT2, was persistently reduced and lipid accumulation was inhibited. Analysis of pathogenic missense mutants of BSCL2 revealed that the amino acid substitution A212P causes aberrant targeting of BSCL2 within the cell, suggesting that subcellular localization of BSCL2 may be critical to its function. CONCLUSIONS This study demonstrates that BSCL2 is an essential, cell-autonomous regulator of adipogenesis.
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Affiliation(s)
- Victoria A Payne
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, UK
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van Beek EA, Bakker AH, Kruyt PM, Vink C, Saris WH, Franssen-van Hal NLW, Keijer J. Comparative expression analysis of isolated human adipocytes and the human adipose cell lines LiSa-2 and PAZ6. Int J Obes (Lond) 2008; 32:912-21. [PMID: 18283285 DOI: 10.1038/ijo.2008.10] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVE To obtain insight in the extent to which the human cell lines LiSa-2 and PAZ6 resemble isolated primary human adipocytes. DESIGN A combination of cDNA subtraction (representative difference analysis; RDA) and cDNA microarray analysis was used to select adipose specific genes to compare isolated (pre-)adipocytes with (un)differentiated LiSa-2 and PAZ6 cells. MEASUREMENTS RDA was performed on adipose tissue against lung tissue. A total of 1400 isolated genes were sequenced and cDNA microarray technology was used for further adipose related gene selection. 30 genes that were found to be enriched in adipose tissue were used to compare isolated human adipocytes and LiSa-2 and PAZ6 cells in the differentiated and undifferentiated states. RESULTS RDA and microarray analysis resulted in the identification of adipose enriched genes, but not in adipose specific genes. Of the 30 most differentially expressed genes, as expected, most were related to lipid metabolism. The second category consisted of methyltransferases, DNMT1, DNMT3a, RNMT and SHMT2, of which the expression was differentiation dependent and higher in differentiated adipocytes. Using the 30 adipose expressed genes, it was found that isolated adipocytes on one hand, and PAZ6 and LiSa-2 adipocytes on the other, differ primarily in lipid metabolism. Furthermore, LiSa-2 cells seem to be more similar to isolated adipocytes than PAZ6 cells. CONCLUSION The LiSa-2 cell line is a good model for differentiated adipocytes, although one should keep in mind that the lipid metabolism in these cells deviates from the in vivo situation Furthermore, our results imply that methylation may have an important function in terminal adipocyte differentiation.
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Affiliation(s)
- E A van Beek
- RIKILT-Institute of Food Safety, Wageningen UR, Wageningen, The Netherlands
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