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Araki M, Nakagawa Y, Saito H, Yamada Y, Han SI, Mizunoe Y, Ohno H, Miyamoto T, Sekiya M, Matsuzaka T, Sone H, Shimano H. Hepatocyte- or macrophage-specific SREBP-1a deficiency in mice exacerbates methionine- and choline-deficient diet-induced nonalcoholic fatty liver disease. Am J Physiol Gastrointest Liver Physiol 2022; 323:G627-G639. [PMID: 36283088 DOI: 10.1152/ajpgi.00090.2022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Sterol regulatory element-binding proteins (SREBPs) are master transcription factors for lipid synthesis, and SREBP-1 is important for fatty acid and triglyceride synthesis. SREBP-1 has two isoforms, SREBP-1a and SREBP-1c, which are splicing variants transcribed from the Srebf1 gene. Although SREBP-1a exhibits stronger transcriptional activity than SREBP-1c, hepatic SREBP-1c is considered more physiologically important. We generated SREBP-1a flox mice using the CRISPR/Cas9 system and hepatocyte- and macrophage-specific SREBP-1a knockout (KO) mice (LKO, liver-knockout; and mΦKO, macrophage-knockout). There were no significant differences among all the mouse genotypes upon feeding with a normal diet. However, feeding with a methionine- and choline-deficient (MCD) diet resulted in exacerbated liver injury in both KO mice. In LKO mice, fatty liver was unexpectedly exacerbated, leading to macrophage infiltration and inflammation. In contrast, in mΦKO mice, the fatty liver state was similar to that in flox mice, but the polarity of the macrophages in the liver was transformed into a proinflammatory M1 subtype, resulting in the exacerbation of inflammation. Taken together, we found that SREBP-1a does not contribute to hepatic lipogenesis, but in either hepatocytes or macrophages distinctly controls the onset of pathological conditions in MCD diet-induced hepatitis.NEW & NOTEWORTHY Hepatocyte- and macrophage-specific SREBP-1a knockout mice were generated for the first time. This study reveals that SREBP-1a does not contribute to hepatic lipogenesis, but in either hepatocytes or macrophages distinctly controls the onset of pathological conditions in methionine- and choline-deficient diet-induced hepatitis.
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Affiliation(s)
- Masaya Araki
- Department of Endocrinology and Metabolism, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Yoshimi Nakagawa
- Department of Endocrinology and Metabolism, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan.,Division of Complex Biosystem Research, Department of Research and Development, Institute of Natural Medicine, University of Toyama, Toyama, Japan.,Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, Tsukuba, Japan
| | - Hodaka Saito
- Division of Complex Biosystem Research, Department of Research and Development, Institute of Natural Medicine, University of Toyama, Toyama, Japan
| | - Yasunari Yamada
- Division of Complex Biosystem Research, Department of Research and Development, Institute of Natural Medicine, University of Toyama, Toyama, Japan
| | - Song-Iee Han
- Department of Endocrinology and Metabolism, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan.,International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Japan
| | - Yuhei Mizunoe
- Department of Endocrinology and Metabolism, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Hiroshi Ohno
- Department of Endocrinology and Metabolism, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Takafumi Miyamoto
- Department of Endocrinology and Metabolism, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Motohiro Sekiya
- Department of Endocrinology and Metabolism, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Takashi Matsuzaka
- Department of Endocrinology and Metabolism, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan.,Transborder Medical Research Center (TMRC), University of Tsukuba, Tsukuba, Japan
| | - Hirohito Sone
- Department of Hematology, Endocrinology and Metabolism, Faculty of Medicine, Niigata University, Niigata, Japan
| | - Hitoshi Shimano
- Department of Endocrinology and Metabolism, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan.,Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, Tsukuba, Japan.,International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Japan.,Japan Agency for Medical Research and Development-Core Research for Evolutional Science and Technology (AMED-CREST), Tokyo, Japan
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2
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The impact of endotrophin on the progression of chronic liver disease. Exp Mol Med 2020; 52:1766-1776. [PMID: 33110211 PMCID: PMC8080612 DOI: 10.1038/s12276-020-00520-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 08/26/2020] [Accepted: 09/07/2020] [Indexed: 01/28/2023] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease and can lead to multiple complications, including non-alcoholic steatohepatitis (NASH), cirrhosis, and hepatocellular carcinoma. The fibrotic liver is characterized by the pathological accumulation of extracellular matrix (ECM) proteins. Type VI collagen alpha3 (Col6a3) is a biomarker of hepatic fibrosis, and its cleaved form, endotrophin (ETP), plays a critical role in adipose tissue dysfunction, insulin resistance, and breast cancer development. Here, we studied the effects of the Col6a3-derived peptide ETP on the progression of chronic liver diseases, such as NASH and liver cancer. We used a doxycycline (Dox)-inducible liver-specific ETP-overexpressing mouse model on a NAFLD-prone (liver-specific SREBP1a transgenic) background. For this, we evaluated the consequences of local ETP expression in the liver and its effect on hepatic inflammation, fibrosis, and insulin resistance. Accumulation of ETP in the liver induced hepatic inflammation and the development of fibrosis with associated insulin resistance. Surprisingly, ETP overexpression also led to the emergence of liver cancer within 10 months in the SREBP1a transgenic background. Our data revealed that ETP can act as a “second hit” during the progression of NAFLD and can play an important role in the development of NASH and hepatocellular carcinoma (HCC). These observations firmly link elevated levels of ETP to chronic liver disease. Localized buildup in the liver of a collagen-derived cleavage fragment plays a critical role in accelerating the development of tissue scarring and liver cancer in mice. Using a transgenic mouse model of fatty liver disease, a team led by Philipp Scherer from the University of Texas Southwestern Medical Center, Dallas, USA, and Jiyoung Park of Ulsan National Institute of Science and Technology, South Korea, showed that liver-specific accumulation of a collagen fragment known as endotrophin leads to activation of inflammatory and fibrotic pathways. The mice subsequently develop metabolic dysfunction, insulin resistance and, with time, cancerous nodules in the liver. The findings suggest that endotrophin accumulation, when it occurs in liver tissue that already contains large depositions of fat, can overwhelm normal liver physiology and accelerate organ damage.
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3
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Ohno H, Matsuzaka T, Tang N, Sharma R, Motomura K, Shimura T, Satoh A, Han SI, Takeuchi Y, Aita Y, Iwasaki H, Yatoh S, Suzuki H, Sekiya M, Nakagawa Y, Sone H, Yahagi N, Yamada N, Higami Y, Shimano H. Transgenic Mice Overexpressing SREBP-1a in Male ob/ob Mice Exhibit Lipodystrophy and Exacerbate Insulin Resistance. Endocrinology 2018; 159:2308-2323. [PMID: 29668871 DOI: 10.1210/en.2017-03179] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 03/13/2018] [Indexed: 12/14/2022]
Abstract
Sterol regulatory element-binding protein (SREBP)-1a is a key transcription factor that activates the expression of genes involved in the synthesis of fatty acids, triglycerides (TGs), and cholesterol. Transgenic mice that overexpress the nuclear form of SREBP-1a under the control of the phosphoenolpyruvate carboxykinase promoter (Tg-1a) were previously shown to display a lipodystrophic phenotype characterized by enlarged and fatty livers, diminished peripheral white adipose tissue (WAT), and insulin resistance. In the current study, we crossed these Tg-1a mice with genetically obese (ob/ob) mice (Tg-1a;ob/ob) and examined change in fat distribution between liver and adipose tissues in severe obesity and mechanism underlying the lipodystrophic phenotype in mice with Tg-1a. Tg-1a;ob/ob mice developed more severe steatohepatitis but had reduced WAT mass and body weight compared with ob/ob mice. The reduction of WAT mass in Tg-1a and Tg-1a;ob/ob mice was accompanied by enhanced lipogenesis and lipid uptake in the liver, reduced plasma lipid levels, impaired adipocyte differentiation, reduced food intake, enhanced energy expenditure, and extended macrophage infiltration and fibrosis in WAT. Despite the improved glucose tolerance, Tg-1a;ob/ob mice showed severe peripheral insulin resistance. Adenoviral hepatic expression of SREBP-1a mimicked these phenotypes. The "fat steal"-like lipodystrophy phenotype of the Tg-1a;ob/ob model demonstrates that hepatic SREBP-1a activation has a strong impact on the partition of TG accumulation, resulting in adipose-tissue remodeling by inflammation and fibrosis and insulin resistance.
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Affiliation(s)
- Hiroshi Ohno
- Department of Internal Medicine (Endocrinology and Metabolism), Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Takashi Matsuzaka
- Department of Internal Medicine (Endocrinology and Metabolism), Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
- Division of Energy Metabolism Research, Transborder Medical Research Center, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Nie Tang
- Department of Internal Medicine (Endocrinology and Metabolism), Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Rahul Sharma
- Department of Internal Medicine (Endocrinology and Metabolism), Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Kaori Motomura
- Department of Internal Medicine (Endocrinology and Metabolism), Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Takuya Shimura
- Department of Internal Medicine (Endocrinology and Metabolism), Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Aoi Satoh
- Department of Internal Medicine (Endocrinology and Metabolism), Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Song-Iee Han
- Department of Internal Medicine (Endocrinology and Metabolism), Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Yoshinori Takeuchi
- Department of Internal Medicine (Endocrinology and Metabolism), Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Yuichi Aita
- Department of Internal Medicine (Endocrinology and Metabolism), Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Hitoshi Iwasaki
- Department of Internal Medicine (Endocrinology and Metabolism), Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Shigeru Yatoh
- Department of Internal Medicine (Endocrinology and Metabolism), Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Hiroaki Suzuki
- Department of Internal Medicine (Endocrinology and Metabolism), Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Motohiro Sekiya
- Department of Internal Medicine (Endocrinology and Metabolism), Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Yoshimi Nakagawa
- International Institute for Integrative Sleep Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Hirohito Sone
- Department of Internal Medicine, Faculty of Medicine, Niigata University, Niigata, Japan
| | - Naoya Yahagi
- Department of Internal Medicine (Endocrinology and Metabolism), Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Nobuhiro Yamada
- Department of Internal Medicine (Endocrinology and Metabolism), Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Yoshikazu Higami
- Laboratory of Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda, Chiba, Japan
| | - Hitoshi Shimano
- Department of Internal Medicine (Endocrinology and Metabolism), Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
- International Institute for Integrative Sleep Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
- Life Science Center of Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba, Ibaraki, Japan
- AMED-CREST, Japan Agency for Medical Research and Development, Chiyoda-ku, Tokyo, Japan
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4
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Engelking LJ, Cantoria MJ, Xu Y, Liang G. Developmental and extrahepatic physiological functions of SREBP pathway genes in mice. Semin Cell Dev Biol 2017; 81:98-109. [PMID: 28736205 DOI: 10.1016/j.semcdb.2017.07.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 07/07/2017] [Indexed: 12/17/2022]
Abstract
Sterol regulatory element-binding proteins (SREBPs), master transcriptional regulators of cholesterol and fatty acid synthesis, have been found to contribute to a diverse array of cellular processes. In this review, we focus on genetically engineered mice in which the activities of six components of the SREBP gene pathway, namely SREBP-1, SREBP-2, Scap, Insig-1, Insig-2, or Site-1 protease have been altered through gene knockout or transgenic approaches. In addition to the expected impacts on lipid metabolism, manipulation of these genes in mice is found to affect a wide array of developmental and physiologic processes ranging from interferon signaling in macrophages to synaptic transmission in the brain. The findings reviewed herein provide a blueprint to guide future studies defining the complex interactions between lipid biology and the physiologic processes of many distinct organ systems.
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Affiliation(s)
- Luke J Engelking
- Departments of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA.
| | - Mary Jo Cantoria
- Departments of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Yanchao Xu
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Guosheng Liang
- Departments of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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5
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Lee D, Son HG, Jung Y, Lee SJV. The role of dietary carbohydrates in organismal aging. Cell Mol Life Sci 2017; 74:1793-1803. [PMID: 27942749 PMCID: PMC11107617 DOI: 10.1007/s00018-016-2432-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Revised: 11/21/2016] [Accepted: 12/05/2016] [Indexed: 12/22/2022]
Abstract
Carbohydrates are essential nutrients that are used as a primary source of energy. Carbohydrate utilization should be properly controlled, as abnormal regulation of carbohydrate metabolism is associated with diseases, such as diabetes, cardiovascular diseases, and stroke. These metabolic syndromes have become a serious problem in developed countries, and there is an increased need for research examining the influence of carbohydrates on animal physiology. Diets enriched in glucose, a major carbohydrate, are also associated with accelerated aging in several model organisms, including yeast and Caenorhabditis elegans (C. elegans). Genetic factors that mediate the effects of high glucose diets on aging have been identified during the last decade, mostly through the use of C. elegans. In this review, we describe studies that determine the effects of carbohydrate-enriched diets on aging by focusing on the mechanisms through which evolutionarily conserved pathways mediate the lifespan-altering effects of glucose in C. elegans. These include the insulin/insulin-like growth factor-1, sterol-regulatory element-binding protein, and AMP-activated protein kinase signaling pathways. We also discuss the effects of various carbohydrates and carbohydrate-derived metabolites on aging in model organisms and cultured mammalian cells. Finally, we discuss how dietary carbohydrates influence health and aging in humans.
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Affiliation(s)
- Dongyeop Lee
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Gyeongbuk, South Korea
| | - Heehwa G Son
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Gyeongbuk, South Korea
| | - Yoonji Jung
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Gyeongbuk, South Korea
| | - Seung-Jae V Lee
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Gyeongbuk, South Korea.
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang, 37673, Gyeongbuk, South Korea.
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6
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Mendelson MM, Marioni RE, Joehanes R, Liu C, Hedman ÅK, Aslibekyan S, Demerath EW, Guan W, Zhi D, Yao C, Huan T, Willinger C, Chen B, Courchesne P, Multhaup M, Irvin MR, Cohain A, Schadt EE, Grove ML, Bressler J, North K, Sundström J, Gustafsson S, Shah S, McRae AF, Harris SE, Gibson J, Redmond P, Corley J, Murphy L, Starr JM, Kleinbrink E, Lipovich L, Visscher PM, Wray NR, Krauss RM, Fallin D, Feinberg A, Absher DM, Fornage M, Pankow JS, Lind L, Fox C, Ingelsson E, Arnett DK, Boerwinkle E, Liang L, Levy D, Deary IJ. Association of Body Mass Index with DNA Methylation and Gene Expression in Blood Cells and Relations to Cardiometabolic Disease: A Mendelian Randomization Approach. PLoS Med 2017; 14:e1002215. [PMID: 28095459 PMCID: PMC5240936 DOI: 10.1371/journal.pmed.1002215] [Citation(s) in RCA: 195] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Accepted: 12/08/2016] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND The link between DNA methylation, obesity, and adiposity-related diseases in the general population remains uncertain. METHODS AND FINDINGS We conducted an association study of body mass index (BMI) and differential methylation for over 400,000 CpGs assayed by microarray in whole-blood-derived DNA from 3,743 participants in the Framingham Heart Study and the Lothian Birth Cohorts, with independent replication in three external cohorts of 4,055 participants. We examined variations in whole blood gene expression and conducted Mendelian randomization analyses to investigate the functional and clinical relevance of the findings. We identified novel and previously reported BMI-related differential methylation at 83 CpGs that replicated across cohorts; BMI-related differential methylation was associated with concurrent changes in the expression of genes in lipid metabolism pathways. Genetic instrumental variable analysis of alterations in methylation at one of the 83 replicated CpGs, cg11024682 (intronic to sterol regulatory element binding transcription factor 1 [SREBF1]), demonstrated links to BMI, adiposity-related traits, and coronary artery disease. Independent genetic instruments for expression of SREBF1 supported the findings linking methylation to adiposity and cardiometabolic disease. Methylation at a substantial proportion (16 of 83) of the identified loci was found to be secondary to differences in BMI. However, the cross-sectional nature of the data limits definitive causal determination. CONCLUSIONS We present robust associations of BMI with differential DNA methylation at numerous loci in blood cells. BMI-related DNA methylation and gene expression provide mechanistic insights into the relationship between DNA methylation, obesity, and adiposity-related diseases.
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Affiliation(s)
- Michael M. Mendelson
- Framingham Heart Study, Framingham, Massachusetts, United States of America
- Boston University School of Medicine, Boston, Massachusetts, United States of America
- Department of Cardiology, Boston Children’s Hospital, Boston, Massachusetts, United States of America
- Population Sciences Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Riccardo E. Marioni
- Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, United Kingdom
- Medical Genetics Section, Centre for Genomic and Experimental Medicine, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland, Australia
| | - Roby Joehanes
- Framingham Heart Study, Framingham, Massachusetts, United States of America
- Population Sciences Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- Hebrew SeniorLife, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Chunyu Liu
- Framingham Heart Study, Framingham, Massachusetts, United States of America
- Population Sciences Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- Department of Biostatistics, Boston University, Boston, Massachusetts, United States of America
| | - Åsa K. Hedman
- Molecular Epidemiology and Science for Life Laboratory, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Stella Aslibekyan
- Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Ellen W. Demerath
- Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Weihua Guan
- Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Degui Zhi
- Department of Biostatistics, School of Public Health, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Chen Yao
- Framingham Heart Study, Framingham, Massachusetts, United States of America
- Population Sciences Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Tianxiao Huan
- Framingham Heart Study, Framingham, Massachusetts, United States of America
- Population Sciences Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Christine Willinger
- Framingham Heart Study, Framingham, Massachusetts, United States of America
- Population Sciences Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Brian Chen
- Population Sciences Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Paul Courchesne
- Framingham Heart Study, Framingham, Massachusetts, United States of America
- Population Sciences Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Michael Multhaup
- Center for Epigenetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Marguerite R. Irvin
- Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Ariella Cohain
- Icahn Institute for Genomics and Multiscale Biology and Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Eric E. Schadt
- Icahn Institute for Genomics and Multiscale Biology and Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Megan L. Grove
- Human Genetics Center, School of Public Health, University of Texas Health Science Center at Houston, Houston, Texas, United States of America
| | - Jan Bressler
- Human Genetics Center, School of Public Health, University of Texas Health Science Center at Houston, Houston, Texas, United States of America
| | - Kari North
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Johan Sundström
- Cardiovascular Epidemiology, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Stefan Gustafsson
- Molecular Epidemiology and Science for Life Laboratory, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Sonia Shah
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland, Australia
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland, Australia
| | - Allan F. McRae
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland, Australia
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland, Australia
| | - Sarah E. Harris
- Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, United Kingdom
- Medical Genetics Section, Centre for Genomic and Experimental Medicine, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Jude Gibson
- Wellcome Trust Clinical Research Facility, Western General Hospital, University of Edinburgh, Edinburgh, United Kingdom
| | - Paul Redmond
- Department of Psychology, University of Edinburgh, Edinburgh, United Kingdom
| | - Janie Corley
- Department of Psychology, University of Edinburgh, Edinburgh, United Kingdom
| | - Lee Murphy
- Wellcome Trust Clinical Research Facility, Western General Hospital, University of Edinburgh, Edinburgh, United Kingdom
| | - John M. Starr
- Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, United Kingdom
- Alzheimer Scotland Dementia Research Centre, University of Edinburgh, Edinburgh, United Kingdom
| | - Erica Kleinbrink
- Center for Molecular Medicine and Genetics and Department of Neurology, Wayne State University, Detroit, Michigan, United States of America
| | - Leonard Lipovich
- Center for Molecular Medicine and Genetics and Department of Neurology, Wayne State University, Detroit, Michigan, United States of America
| | - Peter M. Visscher
- Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, United Kingdom
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland, Australia
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland, Australia
| | - Naomi R. Wray
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland, Australia
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland, Australia
| | - Ronald M. Krauss
- Children’s Hospital Oakland Research Institute, Oakland, California, United States of America
| | - Daniele Fallin
- Center for Epigenetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Andrew Feinberg
- Center for Epigenetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Devin M. Absher
- HudsonAlpha Institute for Biotechnology, Huntsville, Alabama, United States of America
| | - Myriam Fornage
- Human Genetics Center, School of Public Health, University of Texas Health Science Center at Houston, Houston, Texas, United States of America
- Brown Foundation Institute of Molecular Medicine, University of Texas, Houston, Texas, United States of America
| | - James S. Pankow
- Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Lars Lind
- Cardiovascular Epidemiology, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Caroline Fox
- Framingham Heart Study, Framingham, Massachusetts, United States of America
- Population Sciences Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Erik Ingelsson
- Molecular Epidemiology and Science for Life Laboratory, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
- Department of Medicine, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, California, United States of America
| | - Donna K. Arnett
- College of Public Health, University of Kentucky, Lexington, Kentucky, United States of America
| | - Eric Boerwinkle
- Human Genetics Center, School of Public Health, University of Texas Health Science Center at Houston, Houston, Texas, United States of America
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, United States of America
| | - Liming Liang
- Departments of Epidemiology and Biostatistics, School of Public Health, Harvard University, Boston, Massachusetts, United States of America
| | - Daniel Levy
- Framingham Heart Study, Framingham, Massachusetts, United States of America
- Population Sciences Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
| | - Ian J. Deary
- Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, United Kingdom
- Department of Psychology, University of Edinburgh, Edinburgh, United Kingdom
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7
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Pi M, Kapoor K, Ye R, Nishimoto SK, Smith JC, Baudry J, Quarles LD. Evidence for Osteocalcin Binding and Activation of GPRC6A in β-Cells. Endocrinology 2016; 157:1866-80. [PMID: 27007074 PMCID: PMC4870875 DOI: 10.1210/en.2015-2010] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The possibility that G protein-coupled receptor family C member A (GPRC6A) is the osteocalcin (Ocn)-sensing G protein-coupled receptor that directly regulates pancreatic β-cell functions is controversial. In the current study, we found that Ocn and an Ocn-derived C-terminal hexapeptide directly activate GPRC6A-dependent ERK signaling in vitro. Computational models probe the structural basis of Ocn binding to GPRC6A and predict that the C-terminal hexapeptide docks to the extracellular side of the transmembrane domain of GPRC6A. Consistent with the modeling, mutations in the computationally identified binding pocket of GPRC6A reduced Ocn and C-terminal hexapeptide activation of this receptor. In addition, selective deletion of Gprc6a in β-cells (Gprc6a(β)(-cell-cko)) by crossing Gprc6a(flox/flox) mice with Ins2-Cre mice resulted in reduced pancreatic weight, islet number, insulin protein content, and insulin message expression. Both islet size and β-cell proliferation were reduced in Gprc6a(β)(-cell-cko) compared with control mice. Gprc6a(β)(-cell-cko) exhibited abnormal glucose tolerance, but normal insulin sensitivity. Islets isolated from Gprc6a(β)(-cell-cko) mice showed reduced insulin simulation index in response to Ocn. These data establish the structural basis for Ocn direct activation of GPRC6A and confirm a role for GPRC6A in regulating β-cell proliferation and insulin secretion.
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Affiliation(s)
- Min Pi
- Departments of Medicine (M.P., R.Y., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.K.N.), University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S.), University of Tennessee, Knoxville, Tennessee 37996
| | - Karan Kapoor
- Departments of Medicine (M.P., R.Y., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.K.N.), University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S.), University of Tennessee, Knoxville, Tennessee 37996
| | - Ruisong Ye
- Departments of Medicine (M.P., R.Y., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.K.N.), University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S.), University of Tennessee, Knoxville, Tennessee 37996
| | - Satoru Kenneth Nishimoto
- Departments of Medicine (M.P., R.Y., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.K.N.), University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S.), University of Tennessee, Knoxville, Tennessee 37996
| | - Jeremy C Smith
- Departments of Medicine (M.P., R.Y., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.K.N.), University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S.), University of Tennessee, Knoxville, Tennessee 37996
| | - Jerome Baudry
- Departments of Medicine (M.P., R.Y., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.K.N.), University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S.), University of Tennessee, Knoxville, Tennessee 37996
| | - Leigh Darryl Quarles
- Departments of Medicine (M.P., R.Y., L.D.Q.) and Microbiology, Immunology and Biochemistry (S.K.N.), University of Tennessee Health Science Center, Memphis, Tennessee 38163; University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics (K.K., J.C.S., J.B.), Oak Ridge, Tennessee 37830; and Department of Biochemistry and Cellular and Molecular Biology (J.C.S.), University of Tennessee, Knoxville, Tennessee 37996
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8
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Lee D, Jeong DE, Son HG, Yamaoka Y, Kim H, Seo K, Khan AA, Roh TY, Moon DW, Lee Y, Lee SJV. SREBP and MDT-15 protect C. elegans from glucose-induced accelerated aging by preventing accumulation of saturated fat. Genes Dev 2015; 29:2490-503. [PMID: 26637528 PMCID: PMC4691952 DOI: 10.1101/gad.266304.115] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 11/05/2015] [Indexed: 11/25/2022]
Abstract
Glucose-rich diets shorten the life spans of various organisms. However, the metabolic processes involved in this phenomenon remain unknown. Here, we show that sterol regulatory element-binding protein (SREBP) and mediator-15 (MDT-15) prevent the life-shortening effects of a glucose-rich diet by regulating fat-converting processes in Caenorhabditis elegans. Up-regulation of the SREBP/MDT-15 transcription factor complex was necessary and sufficient for alleviating the life-shortening effect of a glucose-rich diet. Glucose feeding induced key enzymes that convert saturated fatty acids (SFAs) to unsaturated fatty acids (UFAs), which are regulated by SREBP and MDT-15. Furthermore, SREBP/MDT-15 reduced the levels of SFAs and moderated glucose toxicity on life span. Our study may help to develop strategies against elevated blood glucose and free fatty acids, which cause glucolipotoxicity in diabetic patients.
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Affiliation(s)
- Dongyeop Lee
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea
| | - Dae-Eun Jeong
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea
| | - Heehwa G Son
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea
| | - Yasuyo Yamaoka
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea
| | - Hyunmin Kim
- Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, South Korea
| | - Keunhee Seo
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea
| | - Abdul Aziz Khan
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea
| | - Tae-Young Roh
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea; Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea
| | - Dae Won Moon
- Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, South Korea
| | - Youngsook Lee
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea; Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea
| | - Seung-Jae V Lee
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea; Information Technology Convergence Engineering, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea; School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea
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9
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Imajo K, Yoneda M, Kessoku T, Ogawa Y, Maeda S, Sumida Y, Hyogo H, Eguchi Y, Wada K, Nakajima A. Rodent models of nonalcoholic fatty liver disease/nonalcoholic steatohepatitis. Int J Mol Sci 2013; 14:21833-57. [PMID: 24192824 PMCID: PMC3856038 DOI: 10.3390/ijms141121833] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 10/14/2013] [Accepted: 10/21/2013] [Indexed: 02/06/2023] Open
Abstract
Research in nonalcoholic fatty liver disease (NAFLD), including nonalcoholic steatohepatitis (NASH), has been limited by the availability of suitable models for this disease. A number of rodent models have been described in which the relevant liver pathology develops in an appropriate metabolic context. These models are promising tools for researchers investigating one of the key issues of NASH: not so much why steatosis occurs, but what causes the transition from simple steatosis to the inflammatory, progressive fibrosing condition of steatohepatitis. The different rodent models can be classified into two large groups. The first includes models in which the disease is acquired after dietary or pharmacological manipulation, and the second, genetically modified models in which liver disease develops spontaneously. To date, no single rodent model has encompassed the full spectrum of human disease progression, but individual models can imitate particular characteristics of human disease. Therefore, it is important that researchers choose the appropriate rodent models. The purpose of the present review is to discuss the metabolic abnormalities present in the currently available rodent models of NAFLD, summarizing the strengths and weaknesses of the established models and the key findings that have furthered our understanding of the disease's pathogenesis.
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Affiliation(s)
- Kento Imajo
- Department of Gastroenterology, Yokohama City University Graduate School of Medicine, 3-9 Fuku-ura, Yokohama 236-0004, Japan; E-Mails: (K.I.); (M.Y.); (T.K.); (Y.O.); (S.M.)
| | - Masato Yoneda
- Department of Gastroenterology, Yokohama City University Graduate School of Medicine, 3-9 Fuku-ura, Yokohama 236-0004, Japan; E-Mails: (K.I.); (M.Y.); (T.K.); (Y.O.); (S.M.)
| | - Takaomi Kessoku
- Department of Gastroenterology, Yokohama City University Graduate School of Medicine, 3-9 Fuku-ura, Yokohama 236-0004, Japan; E-Mails: (K.I.); (M.Y.); (T.K.); (Y.O.); (S.M.)
| | - Yuji Ogawa
- Department of Gastroenterology, Yokohama City University Graduate School of Medicine, 3-9 Fuku-ura, Yokohama 236-0004, Japan; E-Mails: (K.I.); (M.Y.); (T.K.); (Y.O.); (S.M.)
| | - Shin Maeda
- Department of Gastroenterology, Yokohama City University Graduate School of Medicine, 3-9 Fuku-ura, Yokohama 236-0004, Japan; E-Mails: (K.I.); (M.Y.); (T.K.); (Y.O.); (S.M.)
| | - Yoshio Sumida
- Department of Gastroenterology and Hepatology, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto 602-8566, Japan; E-Mail:
| | - Hideyuki Hyogo
- Department of Medicine and Molecular Science, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima 734-8551, Japan; E-Mail:
| | - Yuichiro Eguchi
- Department of Internal Medicine, Saga Medical School, Saga University, Saga 849-8501, Japan; E-Mail:
| | - Koichiro Wada
- Department of Pharmacology, Osaka University Graduate School of Dentistry, 1-8 Yamada-oka, Suita 565-0871, Japan; E-Mail:
| | - Atsushi Nakajima
- Department of Gastroenterology, Yokohama City University Graduate School of Medicine, 3-9 Fuku-ura, Yokohama 236-0004, Japan; E-Mails: (K.I.); (M.Y.); (T.K.); (Y.O.); (S.M.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +81-45-787-2640; Fax: +81-45-784-3546
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10
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Moon HS, Dalamaga M, Kim SY, Polyzos SA, Hamnvik OP, Magkos F, Paruthi J, Mantzoros CS. Leptin's role in lipodystrophic and nonlipodystrophic insulin-resistant and diabetic individuals. Endocr Rev 2013; 34:377-412. [PMID: 23475416 PMCID: PMC3660716 DOI: 10.1210/er.2012-1053] [Citation(s) in RCA: 187] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Leptin is an adipocyte-secreted hormone that has been proposed to regulate energy homeostasis as well as metabolic, reproductive, neuroendocrine, and immune functions. In the context of open-label uncontrolled studies, leptin administration has demonstrated insulin-sensitizing effects in patients with congenital lipodystrophy associated with relative leptin deficiency. Leptin administration has also been shown to decrease central fat mass and improve insulin sensitivity and fasting insulin and glucose levels in HIV-infected patients with highly active antiretroviral therapy (HAART)-induced lipodystrophy, insulin resistance, and leptin deficiency. On the contrary, the effects of leptin treatment in leptin-replete or hyperleptinemic obese individuals with glucose intolerance and diabetes mellitus have been minimal or null, presumably due to leptin tolerance or resistance that impairs leptin action. Similarly, experimental evidence suggests a null or a possibly adverse role of leptin treatment in nonlipodystrophic patients with nonalcoholic fatty liver disease. In this review, we present a description of leptin biology and signaling; we summarize leptin's contribution to glucose metabolism in animals and humans in vitro, ex vivo, and in vivo; and we provide insights into the emerging clinical applications and therapeutic uses of leptin in humans with lipodystrophy and/or diabetes.
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Affiliation(s)
- Hyun-Seuk Moon
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
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Lacaria M, Saha P, Potocki L, Bi W, Yan J, Girirajan S, Burns B, Elsea S, Walz K, Chan L, Lupski JR, Gu W. A duplication CNV that conveys traits reciprocal to metabolic syndrome and protects against diet-induced obesity in mice and men. PLoS Genet 2012; 8:e1002713. [PMID: 22654670 PMCID: PMC3359973 DOI: 10.1371/journal.pgen.1002713] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 03/28/2012] [Indexed: 11/19/2022] Open
Abstract
The functional contribution of CNV to human biology and disease pathophysiology has undergone limited exploration. Recent observations in humans indicate a tentative link between CNV and weight regulation. Smith-Magenis syndrome (SMS), manifesting obesity and hypercholesterolemia, results from a deletion CNV at 17p11.2, but is sometimes due to haploinsufficiency of a single gene, RAI1. The reciprocal duplication in 17p11.2 causes Potocki-Lupski syndrome (PTLS). We previously constructed mouse strains with a deletion, Df(11)17, or duplication, Dp(11)17, of the mouse genomic interval syntenic to the SMS/PTLS region. We demonstrate that Dp(11)17 is obesity-opposing; it conveys a highly penetrant, strain-independent phenotype of reduced weight, leaner body composition, lower TC/LDL, and increased insulin sensitivity that is not due to alteration in food intake or activity level. When fed with a high-fat diet, Dp(11)17/+ mice display much less weight gain and metabolic change than WT mice, demonstrating that the Dp(11)17 CNV protects against metabolic syndrome. Reciprocally, Df(11)17/+ mice with the deletion CNV have increased weight, higher fat content, decreased HDL, and reduced insulin sensitivity, manifesting a bona fide metabolic syndrome. These observations in the deficiency animal model are supported by human data from 76 SMS subjects. Further, studies on knockout/transgenic mice showed that the metabolic consequences of Dp(11)17 and Df(11)17 CNVs are not only due to dosage alterations of Rai1, the predominant dosage-sensitive gene for SMS and likely also PTLS. Our experiments in chromosome-engineered mouse CNV models for human genomic disorders demonstrate that a CNV can be causative for weight/metabolic phenotypes. Furthermore, we explored the biology underlying the contribution of CNV to the physiology of weight control and energy metabolism. The high penetrance, strain independence, and resistance to dietary influences associated with the CNVs in this study are features distinct from most SNP–associated metabolic traits and further highlight the potential importance of CNV in the etiology of both obesity and MetS as well as in the protection from these traits. Genetic factors play a large role in obesity. However, despite recent technical progress in the search for genetic variants, the identities of causative and contributory genetic factors remain largely unknown. Whereas nucleotide sequence variation has been studied extensively with respect to its potential contribution to obesity, copy number variations (CNV), in which genes exist in abnormal numbers of copies mostly due to duplication or deletion, have only more recently been observed to be associated with human obesity. In this report, we utilize chromosome engineered mouse strains harboring a deletion or duplication CNV to address the potential functional impact of CNVs on weight control and metabolism. We show that the duplication CNV leads to lower body weight; it is also metabolically advantageous and protects from diet-induced obesity and metabolic syndrome (MetS). The deletion CNV causes a “mirror” phenotype with increased body weight and MetS–like phenotypes. Importantly, these effects manifest regardless of the genetic background and do not appear to be attributable to any single gene. These findings demonstrate experimentally that CNV can be causative for weight and metabolic phenotypes and highlight the potential relevance and importance of CNV in the etiology of obesity/MetS and the protection from these traits.
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Affiliation(s)
- Melanie Lacaria
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Pradip Saha
- Diabetes and Endocrinology Research Center, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Medicine, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Lorraine Potocki
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Texas Children's Hospital, Houston, Texas, United States of America
| | - Weimin Bi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Jiong Yan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Santhosh Girirajan
- Department of Molecular and Human Genetics, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Brooke Burns
- Department of Pediatrics, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Sarah Elsea
- Department of Molecular and Human Genetics, Virginia Commonwealth University, Richmond, Virginia, United States of America
- Department of Pediatrics, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Katherina Walz
- Department of Human Genetics, University of Miami, Miami, Florida, United States of America
| | - Lawrence Chan
- Diabetes and Endocrinology Research Center, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Medicine, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - James R. Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Texas Children's Hospital, Houston, Texas, United States of America
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
| | - Wenli Gu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
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12
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Whittaker R, Loy PA, Sisman E, Suyama E, Aza-Blanc P, Ingermanson RS, Price JH, McDonough PM. Identification of MicroRNAs that control lipid droplet formation and growth in hepatocytes via high-content screening. ACTA ACUST UNITED AC 2010; 15:798-805. [PMID: 20639500 DOI: 10.1177/1087057110374991] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Hepatic lipid droplets (LDs) are associated with metabolic syndrome, type 2 diabetes, hepatitis C, and both alcoholic and nonalcoholic fatty liver disease. MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression at the level of translation. Approximately 1000 different miRNA species are encoded within the human genome, and many are differentially expressed by healthy and diseased liver. However, few studies have investigated the role of miRNAs in regulating LD expression. Accordingly, a high-content assay (HCA) was performed in which human hepatocytes (Huh-7 cells) were transiently transfected with 327 unique human miRNAs; the cells were then fixed, labeled for nuclei and lipid droplets, and imaged with an automated digital microscopy workstation. LD expression was analyzed on a cell-by-cell basis, using automated image analysis. Eleven miRNAs were identified that altered LDs. MiR-181d was the most efficacious inhibitor, decreasing LDs by about 60%. miRNA-181d was also confirmed to reduce cellular triglycerides and cholesterol ester via biochemical assays. Furthermore, a series of proteins was identified via miRNA target analysis, and siRNAs directed against many of these proteins also modified LDs. Thus, HCA-based screening identified novel miRNA and protein regulators of LDs and cholesterol metabolism that may be relevant to hepatic diseases arising from obesity and alcohol abuse.
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13
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Tilg H, Moschen AR. Inflammatory mechanisms in the regulation of insulin resistance. Mol Med 2008; 14:222-31. [PMID: 18235842 DOI: 10.2119/2007-00119.tilg] [Citation(s) in RCA: 490] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2007] [Accepted: 01/18/2008] [Indexed: 12/18/2022] Open
Abstract
Insulin resistance (IR) plays a key role in the pathophysiology of obesity-related diseases such as type 2 diabetes and nonalcoholic fatty liver disease. It has been demonstrated that IR is associated with a state of chronic low-grade inflammation, and several mediators released from various cell types, including immune cells and adipocytes, have been identified as being involved in the development of IR. Among those are several pro-inflammatory cytokines such as tumor necrosis factor-alpha(TNF-alpha), interleukin (IL)-1, IL-6, and various adipocytokines. Furthermore, several transcription factors and kinases such as c-Jun N-terminal kinase (JNK) and inhibitor of kappa B kinase-beta (IKKbeta), a kinase located proximal of nuclear factor-kappaB (NF-kappaB), participate in this process. Hepatocyte-specific overexpression of NF-kappaB is associated with IR and can mimic all features of fatty liver disease. Whereas the evidence for an important role of many pro-inflammatory pathways in IR in in vitro and animal studies is overwhelming, data from interventional studies in humans to prove this concept are still minor. As a complex network of inflammatory cytokines, adipocytokines, transcription factors, receptor molecules, and acute-phase reactants are involved in the development of IR, new therapeutic approaches in IR-related diseases will be based on a better understanding of their complex interactions.
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Affiliation(s)
- Herbert Tilg
- Department of Gastroenterology and Hepatology, Innsbruck Medical University, Innsbruck, Austria.
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14
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Tilg H, Moschen AR. Inflammatory mechanisms in the regulation of insulin resistance. MOLECULAR MEDICINE (CAMBRIDGE, MASS.) 2008. [PMID: 18235842 DOI: 10.2119/2007-00119] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Insulin resistance (IR) plays a key role in the pathophysiology of obesity-related diseases such as type 2 diabetes and nonalcoholic fatty liver disease. It has been demonstrated that IR is associated with a state of chronic low-grade inflammation, and several mediators released from various cell types, including immune cells and adipocytes, have been identified as being involved in the development of IR. Among those are several pro-inflammatory cytokines such as tumor necrosis factor-alpha(TNF-alpha), interleukin (IL)-1, IL-6, and various adipocytokines. Furthermore, several transcription factors and kinases such as c-Jun N-terminal kinase (JNK) and inhibitor of kappa B kinase-beta (IKKbeta), a kinase located proximal of nuclear factor-kappaB (NF-kappaB), participate in this process. Hepatocyte-specific overexpression of NF-kappaB is associated with IR and can mimic all features of fatty liver disease. Whereas the evidence for an important role of many pro-inflammatory pathways in IR in in vitro and animal studies is overwhelming, data from interventional studies in humans to prove this concept are still minor. As a complex network of inflammatory cytokines, adipocytokines, transcription factors, receptor molecules, and acute-phase reactants are involved in the development of IR, new therapeutic approaches in IR-related diseases will be based on a better understanding of their complex interactions.
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Affiliation(s)
- Herbert Tilg
- Department of Gastroenterology and Hepatology, Innsbruck Medical University, Innsbruck, Austria.
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15
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Xia Y, Wan X, Duan Q, He S, Wang X. Inhibition of protein kinase B by palmitate in the insulin signaling of HepG2 cells and the preventive effect of arachidonic acid on insulin resistance. ACTA ACUST UNITED AC 2007; 1:200-6. [PMID: 24557677 DOI: 10.1007/s11684-007-0038-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2006] [Accepted: 02/28/2007] [Indexed: 11/27/2022]
Abstract
Elevated plasma levels of free fatty acids (FFAs) may contribute to insulin resistance (IR) that is characteristic of type 2 diabetes mellitus. In this study, we investigated the effects of two fatty acids, palmitate (PA) and arachidonic acid (AA) on glycogenesis under insulin signaling in HepG2cells, a transformed hepatic carcinoma cell line. In the presence of 200 μmol of palmitate, insulin (10(-7) mol/L) stimulation of glycogenesis was inhibited, as evidenced by increased glucose in the medium and decreased intracellular glycogen. Wortmannin (WM), a specific inhibitor of PI3K, dramatically decreased the amount of intracellular glycogen in cells without PA incubation. However, glycogen in PA treated cells was not significantly changed by WM, indicating that PA may also act on PI3K. Interestingly, AA restored the effects of WM inhibition on glycogenesis in PA cells. Western blot analysis demonstrated that PA in the absence of WM increased phosphorylated glycogen synthase (inactive form of GS) and decreased phosphorylated protein kinase B (active form of PKB), causing a reduction of intracellular glycogen. AA, however, reversed the effects of PA on GS and PKB. Furthermore, inhibition of protein kinase C (PKC) by a specific inhibitor chelerythrine chloride (CC) abolished the inhibitory effect of PA on glycogen synthesis by decreasing phosphorylated GS and increasing phosphorylated PKB. However, the effect of CC in the presence of PA disappeared when AA was also present.Our results suggest that there is a disruption of the insulin signaling pathway between PKB and GS when the cells were exposed to PA, contributing to IR. PA may also interrupt the PKC signaling pathway. In contrast, AA could rescue glycogenesis impaired by PA.
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Affiliation(s)
- Yanzhi Xia
- Department of Medical Biology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
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16
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Sakurai M, Takamura T, Ota T, Ando H, Akahori H, Kaji K, Sasaki M, Nakanuma Y, Miura K, Kaneko S. Liver steatosis, but not fibrosis, is associated with insulin resistance in nonalcoholic fatty liver disease. J Gastroenterol 2007; 42:312-7. [PMID: 17464461 DOI: 10.1007/s00535-006-1948-] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2006] [Accepted: 12/19/2006] [Indexed: 02/07/2023]
Abstract
BACKGROUND To address the hypothesis that liver steatosis causes systemic insulin resistance, we sought to determine the liver histological feature that most strongly contributes to insulin resistance in patients with nonalcoholic fatty liver disease (NAFLD). METHODS Liver biopsy specimens were obtained from 131 patients with clinically suspected NAFLD. The stage, grade of nonalcoholic steatohepatitis (NASH), and level of steatosis were scored and analyzed in relation to the homeostasis model assessment of insulin resistance (HOMA-IR) and the metabolic clearance rate (MCR), measured using the glucose clamp method. RESULTS In the univariate analysis, the degree of hepatic steatosis (r = 0.458, P < 0.001), stage (r = 0.360, P < 0.001), and grade (r = 0.349, P < 0.01) of NASH were significantly correlated with the HOMA-IR. Multiple regression analysis adjusting for age, sex, body mass index, and each histological score showed that steatosis was significantly and independently associated with HOMA-IR (coefficient = 1.42, P < 0.001), but not with the stage (coefficient = 0.33, P = 0.307) or grade (coefficient = 0.67, P = 0.134) of NASH. Similar independent relationships were observed between steatosis and MCR, but the relationship was weaker (coefficient = -0.98, P = 0.076). CONCLUSIONS Steatosis of the liver, but not the stage or the grade of NASH, is associated with insulin resistance in patients with NAFLD.
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Affiliation(s)
- Masaru Sakurai
- Department of Disease Control and Homeostacis, Kanazawa University Graduate School of Medical Science, 13-1 Takara-machi, Kanazawa, Ishikawa, 920-8641, Japan
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Metón I, Egea M, Anemaet IG, Fernández F, Baanante IV. Sterol regulatory element binding protein-1a transactivates 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase gene promoter. Endocrinology 2006; 147:3446-56. [PMID: 16614080 DOI: 10.1210/en.2005-1506] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
6-Phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB) catalyzes the synthesis and degradation of fructose-2,6-bisphosphate, a key modulator of glycolysis-gluconeogenesis. To gain insight into the molecular mechanism behind hormonal and nutritional regulation of PFKFB expression, we have cloned and characterized the proximal promoter region of the liver isoform of PFKFB (PFKFB1) from gilthead sea bream (Sparus aurata). Transient transfection of HepG2 cells with deleted gene promoter constructs and electrophoretic mobility shift assays allowed us to identify a sterol regulatory element (SRE) to which SRE binding protein-1a (SREBP-1a) binds and transactivates PFKFB1 gene transcription. Mutating the SRE box abolished SREBP-1a binding and transactivation. The in vivo binding of SREBP-1a to the SRE box in the S. aurata PFKFB1 promoter was confirmed by chromatin immunoprecipitation assays. There is a great deal of evidence for a postprandial rise of PFKB1 mRNA levels in fish and rats. Consistently, starved-to-fed transition and treatment with glucose or insulin increased SREBP-1 immunodetectable levels, SREBP-1 association to PFKFB1 promoter, and PFKFB1 mRNA levels in the piscine liver. Our findings demonstrate involvement of SREBP-1a in the transcriptional activation of PFKFB1, and we conclude that SREBP-1a may exert a key role mediating postprandial activation of PFKFB1 transcription.
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Affiliation(s)
- Isidoro Metón
- Departament de Bioquímica i Biologia Molecular, Facultat de Farmàcia, Universitat de Barcelona, Diagonal 643, 08028 Barcelona, Spain
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Avramoglu RK, Basciano H, Adeli K. Lipid and lipoprotein dysregulation in insulin resistant states. Clin Chim Acta 2006; 368:1-19. [PMID: 16480697 DOI: 10.1016/j.cca.2005.12.026] [Citation(s) in RCA: 186] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2005] [Revised: 12/15/2005] [Accepted: 12/20/2005] [Indexed: 12/30/2022]
Abstract
Insulin resistant states are commonly associated with an atherogenic dyslipidemia that contributes to significantly higher risk of atherosclerosis and cardiovascular disease. Indeed, disorders of carbohydrate and lipid metabolism co-exist in the majority of subjects with the "metabolic syndrome" and form the basis for the definition and diagnosis of this complex syndrome. The most fundamental defect in these patients is resistance to cellular actions of insulin, particularly resistance to insulin-stimulated glucose uptake. Insulin insensitivity appears to cause hyperinsulinemia, enhanced hepatic gluconeogenesis and glucose output, reduced suppression of lipolysis in adipose tissue leading to a high free fatty acid flux, and increased hepatic very low density lipoprotein (VLDL) secretion causing hypertriglyceridemia and reduced plasma levels of high density lipoprotein (HDL) cholesterol. Although the link between insulin resistance and dysregulation of lipoprotein metabolism is well established, a significant gap of knowledge exists regarding the underlying cellular and molecular mechanisms. Emerging evidence suggests that insulin resistance and its associated metabolic dyslipidemia result from perturbations in key molecules of the insulin signaling pathway, including overexpression of key phosphatases, downregulation and/or activation of key protein kinase cascades, leading to a state of mixed hepatic insulin resistance and sensitivity. These signaling changes in turn cause an increased expression of sterol regulatory element binding protein (SREBP) 1c, induction of de novo lipogensis and higher activity of microsomal triglyceride transfer protein (MTP), which together with high exogenous free fatty acid (FFA) flux collectively stimulate the hepatic production of apolipoprotein B (apoB)-containing VLDL particles. VLDL overproduction underlies the high triglyceride/low HDL-cholesterol lipid profile commonly observed in insulin resistant subjects.
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Affiliation(s)
- Rita Kohen Avramoglu
- Clinical Biochemistry Division, Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada M5G 1X8
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