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Hui ST, Parks BW, Org E, Norheim F, Che N, Pan C, Castellani LW, Charugundla S, Dirks DL, Psychogios N, Neuhaus I, Gerszten RE, Kirchgessner T, Gargalovic PS, Lusis AJ. The genetic architecture of NAFLD among inbred strains of mice. eLife 2015; 4:e05607. [PMID: 26067236 PMCID: PMC4493743 DOI: 10.7554/elife.05607] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 06/11/2015] [Indexed: 02/06/2023] Open
Abstract
To identify genetic and environmental factors contributing to the pathogenesis of non-alcoholic fatty liver disease, we examined liver steatosis and related clinical and molecular traits in more than 100 unique inbred mouse strains, which were fed a diet rich in fat and carbohydrates. A >30-fold variation in hepatic TG accumulation was observed among the strains. Genome-wide association studies revealed three loci associated with hepatic TG accumulation. Utilizing transcriptomic data from the liver and adipose tissue, we identified several high-confidence candidate genes for hepatic steatosis, including Gde1, a glycerophosphodiester phosphodiesterase not previously implicated in triglyceride metabolism. We confirmed the role of Gde1 by in vivo hepatic over-expression and shRNA knockdown studies. We hypothesize that Gde1 expression increases TG production by contributing to the production of glycerol-3-phosphate. Our multi-level data, including transcript levels, metabolite levels, and gut microbiota composition, provide a framework for understanding genetic and environmental interactions underlying hepatic steatosis.
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Affiliation(s)
- Simon T Hui
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Brian W Parks
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Elin Org
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Frode Norheim
- Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Nam Che
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Calvin Pan
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Lawrence W Castellani
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Sarada Charugundla
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Darwin L Dirks
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Nikolaos Psychogios
- Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, United States
| | - Isaac Neuhaus
- Department of Computational Genomics, Bristol-Myers Squibb, Princeton, United States
| | - Robert E Gerszten
- Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, United States
| | - Todd Kirchgessner
- Department of Cardiovascular Drug Discovery, Bristol-Myers Squibb, Princeton, United States
| | - Peter S Gargalovic
- Department of Computational Genomics, Bristol-Myers Squibb, Princeton, United States
| | - Aldons J Lusis
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
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2
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Domigan CK, Warren CM, Antanesian V, Happel K, Ziyad S, Lee S, Krall A, Duan L, Torres-Collado AX, Castellani LW, Elashoff D, Christofk HR, van der Bliek AM, Potente M, Iruela-Arispe ML. Autocrine VEGF maintains endothelial survival through regulation of metabolism and autophagy. J Cell Sci 2015; 128:2236-48. [PMID: 25956888 DOI: 10.1242/jcs.163774] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 04/30/2015] [Indexed: 12/12/2022] Open
Abstract
Autocrine VEGF is necessary for endothelial survival, although the cellular mechanisms supporting this function are unknown. Here, we show that--even after full differentiation and maturation--continuous expression of VEGF by endothelial cells is needed to sustain vascular integrity and cellular viability. Depletion of VEGF from the endothelium results in mitochondria fragmentation and suppression of glucose metabolism, leading to increased autophagy that contributes to cell death. Gene-expression profiling showed that endothelial VEGF contributes to the regulation of cell cycle and mitochondrial gene clusters, as well as several--but not all--targets of the transcription factor FOXO1. Indeed, VEGF-deficient endothelium in vitro and in vivo showed increased levels of FOXO1 protein in the nucleus and cytoplasm. Silencing of FOXO1 in VEGF-depleted cells reversed expression profiles of several of the gene clusters that were de-regulated in VEGF knockdown, and rescued both cell death and autophagy phenotypes. Our data suggest that endothelial VEGF maintains vascular homeostasis through regulation of FOXO1 levels, thereby ensuring physiological metabolism and endothelial cell survival.
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Affiliation(s)
- Courtney K Domigan
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90024, USA
| | - Carmen M Warren
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90024, USA
| | - Vaspour Antanesian
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90024, USA
| | - Katharina Happel
- Angiogenesis and Metabolism Laboratory, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Safiyyah Ziyad
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90024, USA
| | - Sunyoung Lee
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90024, USA
| | - Abigail Krall
- Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA 90024, USA
| | - Lewei Duan
- Department of Medicine Statistics Core, University of California, Los Angeles, Los Angeles, CA 90024, USA
| | - Antoni X Torres-Collado
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90024, USA
| | | | - David Elashoff
- Department of Medicine Statistics Core, University of California, Los Angeles, Los Angeles, CA 90024, USA
| | - Heather R Christofk
- Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA 90024, USA
| | - Alexander M van der Bliek
- Jonsson Comprehensive Cancer Center, University of California, Los Angeles, CA 90024, USA Biological Chemistry, University of California, Los Angeles, Los Angeles, CA 90024, USA
| | - Michael Potente
- Angiogenesis and Metabolism Laboratory, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - M Luisa Iruela-Arispe
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90024, USA Molecular Biology Institute, University of California, Los Angeles, CA 90024, USA Jonsson Comprehensive Cancer Center, University of California, Los Angeles, CA 90024, USA
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3
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Shih DM, Yu JM, Vergnes L, Dali-Youcef N, Champion MD, Devarajan A, Zhang P, Castellani LW, Brindley DN, Jamey C, Auwerx J, Reddy ST, Ford DA, Reue K, Lusis AJ. PON3 knockout mice are susceptible to obesity, gallstone formation, and atherosclerosis. FASEB J 2015; 29:1185-97. [PMID: 25477283 PMCID: PMC4396607 DOI: 10.1096/fj.14-260570] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 11/07/2014] [Indexed: 11/11/2022]
Abstract
We report the engineering and characterization of paraoxonase-3 knockout mice (Pon3KO). The mice were generally healthy but exhibited quantitative alterations in bile acid metabolism and a 37% increased body weight compared to the wild-type mice on a high fat diet. PON3 was enriched in the mitochondria-associated membrane fraction of hepatocytes. PON3 deficiency resulted in impaired mitochondrial respiration, increased mitochondrial superoxide levels, and increased hepatic expression of inflammatory genes. PON3 deficiency did not influence atherosclerosis development on an apolipoprotein E null hyperlipidemic background, but it did lead to a significant 60% increase in atherosclerotic lesion size in Pon3KO mice on the C57BL/6J background when fed a cholate-cholesterol diet. On the diet, the Pon3KO had significantly increased plasma intermediate-density lipoprotein/LDL cholesterol and bile acid levels. They also exhibited significantly elevated levels of hepatotoxicity markers in circulation, a 58% increase in gallstone weight, a 40% increase in hepatic cholesterol level, and increased mortality. Furthermore, Pon3KO mice exhibited decreased hepatic bile acid synthesis and decreased bile acid levels in the small intestine compared with wild-type mice. Our study suggests a role for PON3 in the metabolism of lipid and bile acid as well as protection against atherosclerosis, gallstone disease, and obesity.
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Affiliation(s)
- Diana M Shih
- *Division of Cardiology, Department of Medicine, Department of Microbiology, Immunology, and Molecular Genetics, Department of Human Genetics, Department of Molecular and Medical Pharmacology, and Department of Medicine and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California, USA; IGBMC, Illkirch and Hôpitaux Universitaires de Strasbourg, and **Laboratoire de Toxicologie, Universitaires de Strasbourg, Strasbourg, France; Department of Biochemistry and Molecular Biology, and Center for Cardiovascular Research, St. Louis University School of Medicine, St. Louis, Missouri, USA; University of Alberta, Edmonton, Alberta, Canada; and Laboratory for Integrative and Systems Physiology, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Janet M Yu
- *Division of Cardiology, Department of Medicine, Department of Microbiology, Immunology, and Molecular Genetics, Department of Human Genetics, Department of Molecular and Medical Pharmacology, and Department of Medicine and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California, USA; IGBMC, Illkirch and Hôpitaux Universitaires de Strasbourg, and **Laboratoire de Toxicologie, Universitaires de Strasbourg, Strasbourg, France; Department of Biochemistry and Molecular Biology, and Center for Cardiovascular Research, St. Louis University School of Medicine, St. Louis, Missouri, USA; University of Alberta, Edmonton, Alberta, Canada; and Laboratory for Integrative and Systems Physiology, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Laurent Vergnes
- *Division of Cardiology, Department of Medicine, Department of Microbiology, Immunology, and Molecular Genetics, Department of Human Genetics, Department of Molecular and Medical Pharmacology, and Department of Medicine and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California, USA; IGBMC, Illkirch and Hôpitaux Universitaires de Strasbourg, and **Laboratoire de Toxicologie, Universitaires de Strasbourg, Strasbourg, France; Department of Biochemistry and Molecular Biology, and Center for Cardiovascular Research, St. Louis University School of Medicine, St. Louis, Missouri, USA; University of Alberta, Edmonton, Alberta, Canada; and Laboratory for Integrative and Systems Physiology, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Nassim Dali-Youcef
- *Division of Cardiology, Department of Medicine, Department of Microbiology, Immunology, and Molecular Genetics, Department of Human Genetics, Department of Molecular and Medical Pharmacology, and Department of Medicine and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California, USA; IGBMC, Illkirch and Hôpitaux Universitaires de Strasbourg, and **Laboratoire de Toxicologie, Universitaires de Strasbourg, Strasbourg, France; Department of Biochemistry and Molecular Biology, and Center for Cardiovascular Research, St. Louis University School of Medicine, St. Louis, Missouri, USA; University of Alberta, Edmonton, Alberta, Canada; and Laboratory for Integrative and Systems Physiology, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Matthew D Champion
- *Division of Cardiology, Department of Medicine, Department of Microbiology, Immunology, and Molecular Genetics, Department of Human Genetics, Department of Molecular and Medical Pharmacology, and Department of Medicine and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California, USA; IGBMC, Illkirch and Hôpitaux Universitaires de Strasbourg, and **Laboratoire de Toxicologie, Universitaires de Strasbourg, Strasbourg, France; Department of Biochemistry and Molecular Biology, and Center for Cardiovascular Research, St. Louis University School of Medicine, St. Louis, Missouri, USA; University of Alberta, Edmonton, Alberta, Canada; and Laboratory for Integrative and Systems Physiology, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Asokan Devarajan
- *Division of Cardiology, Department of Medicine, Department of Microbiology, Immunology, and Molecular Genetics, Department of Human Genetics, Department of Molecular and Medical Pharmacology, and Department of Medicine and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California, USA; IGBMC, Illkirch and Hôpitaux Universitaires de Strasbourg, and **Laboratoire de Toxicologie, Universitaires de Strasbourg, Strasbourg, France; Department of Biochemistry and Molecular Biology, and Center for Cardiovascular Research, St. Louis University School of Medicine, St. Louis, Missouri, USA; University of Alberta, Edmonton, Alberta, Canada; and Laboratory for Integrative and Systems Physiology, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Peixiang Zhang
- *Division of Cardiology, Department of Medicine, Department of Microbiology, Immunology, and Molecular Genetics, Department of Human Genetics, Department of Molecular and Medical Pharmacology, and Department of Medicine and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California, USA; IGBMC, Illkirch and Hôpitaux Universitaires de Strasbourg, and **Laboratoire de Toxicologie, Universitaires de Strasbourg, Strasbourg, France; Department of Biochemistry and Molecular Biology, and Center for Cardiovascular Research, St. Louis University School of Medicine, St. Louis, Missouri, USA; University of Alberta, Edmonton, Alberta, Canada; and Laboratory for Integrative and Systems Physiology, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Lawrence W Castellani
- *Division of Cardiology, Department of Medicine, Department of Microbiology, Immunology, and Molecular Genetics, Department of Human Genetics, Department of Molecular and Medical Pharmacology, and Department of Medicine and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California, USA; IGBMC, Illkirch and Hôpitaux Universitaires de Strasbourg, and **Laboratoire de Toxicologie, Universitaires de Strasbourg, Strasbourg, France; Department of Biochemistry and Molecular Biology, and Center for Cardiovascular Research, St. Louis University School of Medicine, St. Louis, Missouri, USA; University of Alberta, Edmonton, Alberta, Canada; and Laboratory for Integrative and Systems Physiology, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - David N Brindley
- *Division of Cardiology, Department of Medicine, Department of Microbiology, Immunology, and Molecular Genetics, Department of Human Genetics, Department of Molecular and Medical Pharmacology, and Department of Medicine and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California, USA; IGBMC, Illkirch and Hôpitaux Universitaires de Strasbourg, and **Laboratoire de Toxicologie, Universitaires de Strasbourg, Strasbourg, France; Department of Biochemistry and Molecular Biology, and Center for Cardiovascular Research, St. Louis University School of Medicine, St. Louis, Missouri, USA; University of Alberta, Edmonton, Alberta, Canada; and Laboratory for Integrative and Systems Physiology, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Carole Jamey
- *Division of Cardiology, Department of Medicine, Department of Microbiology, Immunology, and Molecular Genetics, Department of Human Genetics, Department of Molecular and Medical Pharmacology, and Department of Medicine and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California, USA; IGBMC, Illkirch and Hôpitaux Universitaires de Strasbourg, and **Laboratoire de Toxicologie, Universitaires de Strasbourg, Strasbourg, France; Department of Biochemistry and Molecular Biology, and Center for Cardiovascular Research, St. Louis University School of Medicine, St. Louis, Missouri, USA; University of Alberta, Edmonton, Alberta, Canada; and Laboratory for Integrative and Systems Physiology, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Johan Auwerx
- *Division of Cardiology, Department of Medicine, Department of Microbiology, Immunology, and Molecular Genetics, Department of Human Genetics, Department of Molecular and Medical Pharmacology, and Department of Medicine and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California, USA; IGBMC, Illkirch and Hôpitaux Universitaires de Strasbourg, and **Laboratoire de Toxicologie, Universitaires de Strasbourg, Strasbourg, France; Department of Biochemistry and Molecular Biology, and Center for Cardiovascular Research, St. Louis University School of Medicine, St. Louis, Missouri, USA; University of Alberta, Edmonton, Alberta, Canada; and Laboratory for Integrative and Systems Physiology, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Srinivasa T Reddy
- *Division of Cardiology, Department of Medicine, Department of Microbiology, Immunology, and Molecular Genetics, Department of Human Genetics, Department of Molecular and Medical Pharmacology, and Department of Medicine and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California, USA; IGBMC, Illkirch and Hôpitaux Universitaires de Strasbourg, and **Laboratoire de Toxicologie, Universitaires de Strasbourg, Strasbourg, France; Department of Biochemistry and Molecular Biology, and Center for Cardiovascular Research, St. Louis University School of Medicine, St. Louis, Missouri, USA; University of Alberta, Edmonton, Alberta, Canada; and Laboratory for Integrative and Systems Physiology, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - David A Ford
- *Division of Cardiology, Department of Medicine, Department of Microbiology, Immunology, and Molecular Genetics, Department of Human Genetics, Department of Molecular and Medical Pharmacology, and Department of Medicine and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California, USA; IGBMC, Illkirch and Hôpitaux Universitaires de Strasbourg, and **Laboratoire de Toxicologie, Universitaires de Strasbourg, Strasbourg, France; Department of Biochemistry and Molecular Biology, and Center for Cardiovascular Research, St. Louis University School of Medicine, St. Louis, Missouri, USA; University of Alberta, Edmonton, Alberta, Canada; and Laboratory for Integrative and Systems Physiology, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Karen Reue
- *Division of Cardiology, Department of Medicine, Department of Microbiology, Immunology, and Molecular Genetics, Department of Human Genetics, Department of Molecular and Medical Pharmacology, and Department of Medicine and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California, USA; IGBMC, Illkirch and Hôpitaux Universitaires de Strasbourg, and **Laboratoire de Toxicologie, Universitaires de Strasbourg, Strasbourg, France; Department of Biochemistry and Molecular Biology, and Center for Cardiovascular Research, St. Louis University School of Medicine, St. Louis, Missouri, USA; University of Alberta, Edmonton, Alberta, Canada; and Laboratory for Integrative and Systems Physiology, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Aldons J Lusis
- *Division of Cardiology, Department of Medicine, Department of Microbiology, Immunology, and Molecular Genetics, Department of Human Genetics, Department of Molecular and Medical Pharmacology, and Department of Medicine and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California, USA; IGBMC, Illkirch and Hôpitaux Universitaires de Strasbourg, and **Laboratoire de Toxicologie, Universitaires de Strasbourg, Strasbourg, France; Department of Biochemistry and Molecular Biology, and Center for Cardiovascular Research, St. Louis University School of Medicine, St. Louis, Missouri, USA; University of Alberta, Edmonton, Alberta, Canada; and Laboratory for Integrative and Systems Physiology, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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4
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Parks BW, Sallam T, Mehrabian M, Psychogios N, Hui ST, Norheim F, Castellani LW, Rau CD, Pan C, Phun J, Zhou Z, Yang WP, Neuhaus I, Gargalovic PS, Kirchgessner TG, Graham M, Lee R, Tontonoz P, Gerszten RE, Hevener AL, Lusis AJ. Genetic architecture of insulin resistance in the mouse. Cell Metab 2015. [PMID: 25651185 DOI: 10.1016/j.cmet.2015.01.002.genetic] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/20/2023]
Abstract
Insulin resistance (IR) is a complex trait with multiple genetic and environmental components. Confounded by large differences between the sexes, environment, and disease pathology, the genetic basis of IR has been difficult to dissect. Here we examine IR and related traits in a diverse population of more than 100 unique male and female inbred mouse strains after feeding a diet rich in fat and refined carbohydrates. Our results show dramatic variation in IR among strains of mice and widespread differences between sexes that are dependent on genotype. We uncover more than 15 genome-wide significant loci and validate a gene, Agpat5, associated with IR. We also integrate plasma metabolite levels and global gene expression from liver and adipose tissue to identify metabolite quantitative trait loci (mQTL) and expression QTL (eQTL), respectively. Our results provide a resource for analysis of interactions between diet, sex, and genetic background in IR.
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Affiliation(s)
- Brian W Parks
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Tamer Sallam
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Margarete Mehrabian
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Nikolas Psychogios
- Cardiovascular Research Center and Cardiology Division, Harvard Medical School, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Simon T Hui
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Frode Norheim
- Department of Nutrition, Faculty of Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway
| | - Lawrence W Castellani
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Christoph D Rau
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Calvin Pan
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Jennifer Phun
- Division of Endocrinology, Diabetes and Hypertension, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Zhenqi Zhou
- Division of Endocrinology, Diabetes and Hypertension, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Wen-Pin Yang
- Department of Applied Genomics, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Isaac Neuhaus
- Department of Applied Genomics, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Peter S Gargalovic
- Department of Cardiovascular Drug Discovery, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Todd G Kirchgessner
- Department of Cardiovascular Drug Discovery, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Mark Graham
- Isis Pharmaceuticals, Carlsbad, CA 92008, USA
| | - Richard Lee
- Isis Pharmaceuticals, Carlsbad, CA 92008, USA
| | - Peter Tontonoz
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Howard Hughes Medical Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Robert E Gerszten
- Cardiovascular Research Center and Cardiology Division, Harvard Medical School, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Andrea L Hevener
- Division of Endocrinology, Diabetes and Hypertension, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Aldons J Lusis
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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5
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Okamoto R, Gery S, Gombart AF, Wang X, Castellani LW, Akagi T, Chen S, Arditi M, Ho Q, Lusis AJ, Li Q, Koeffler HP. Deficiency of CCAAT/enhancer binding protein-epsilon reduces atherosclerotic lesions in LDLR-/- mice. PLoS One 2014; 9:e85341. [PMID: 24489659 PMCID: PMC3904867 DOI: 10.1371/journal.pone.0085341] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 12/04/2013] [Indexed: 01/23/2023] Open
Abstract
The CCAAT/enhancer binding proteins (C/EBPs) are transcription factors involved in hematopoietic cell development and induction of several inflammatory mediators. C/EBPε is expressed only in myeloid cells including monocytes/macrophages. Atherosclerosis is an inflammatory disorder of the vascular wall and circulating immune cells such as monocytes/macrophages. Mice deficient in the low density lipoprotein (LDL) receptor (Ldlr−/−) fed on a high cholesterol diet (HCD) show elevated blood cholesterol levels and are widely used as models to study human atherosclerosis. In this study, we generated Ldlr and Cebpe double-knockout (llee) mice and compared their atherogenic phenotypes to Ldlr single deficient (llEE) mice after HCD. Macrophages from llee mice have reduced lipid uptake by foam cells and impaired phagokinetic motility in vitro compared to macrophages from llEE mice. Also, compared to llEE mice, llee mice have alterations of lipid metabolism, and reduced atheroma and obesity, particularly the males. Peritoneal macrophages of llee male mice have reduced mRNA expression of FABP4, a fatty acid binding protein implicated in atherosclerosis. Overall, our study suggests that the myeloid specific factor C/EBPε is involved in systemic lipid metabolism and that silencing of C/EBPε could decrease the development of atherosclerosis.
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Affiliation(s)
- Ryoko Okamoto
- Division of Hematology and Oncology, Cedars-Sinai Medical Center, University of California Los Angeles (UCLA) School of Medicine, Los Angeles, California, United States of America
| | - Sigal Gery
- Division of Hematology and Oncology, Cedars-Sinai Medical Center, University of California Los Angeles (UCLA) School of Medicine, Los Angeles, California, United States of America
- * E-mail:
| | - Adrian F. Gombart
- Division of Hematology and Oncology, Cedars-Sinai Medical Center, University of California Los Angeles (UCLA) School of Medicine, Los Angeles, California, United States of America
- Department of Biochemisty and Biophysics, Linus Pauling Institute, Oregon State University, Corvallis, Oregon, United States of America
| | - Xuping Wang
- Department of Human Genetics, Department of Medicine, and Department of Microbiology, Molecular Genetics, and Immunology, David Geffen School of Medicine at University of California Los Angeles (UCLA), Los Angeles, California, United States of America
| | - Lawrence W. Castellani
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine at University of California Los Angeles (UCLA), Los Angeles, California, United States of America
| | - Tadayuki Akagi
- Division of Hematology and Oncology, Cedars-Sinai Medical Center, University of California Los Angeles (UCLA) School of Medicine, Los Angeles, California, United States of America
| | - Shuang Chen
- Division of Pediatric Infectious Diseases and Immunology, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Moshe Arditi
- Division of Pediatric Infectious Diseases and Immunology, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Quoc Ho
- Division of Hematology and Oncology, Cedars-Sinai Medical Center, University of California Los Angeles (UCLA) School of Medicine, Los Angeles, California, United States of America
| | - Aldons J. Lusis
- Department of Human Genetics, Department of Medicine, and Department of Microbiology, Molecular Genetics, and Immunology, David Geffen School of Medicine at University of California Los Angeles (UCLA), Los Angeles, California, United States of America
| | - Quanlin Li
- Biostatistics and Bioinformatics Research Center, Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - H. Phillip Koeffler
- Division of Hematology and Oncology, Cedars-Sinai Medical Center, University of California Los Angeles (UCLA) School of Medicine, Los Angeles, California, United States of America
- Cancer Science Institute of Singapore and National Cancer Institute, National University of Singapore, Singapore, Singapore
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6
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Parks BW, Nam E, Org E, Kostem E, Norheim F, Hui ST, Pan C, Civelek M, Rau CD, Bennett BJ, Mehrabian M, Ursell LK, He A, Castellani LW, Zinker B, Kirby M, Drake TA, Drevon CA, Knight R, Gargalovic P, Kirchgessner T, Eskin E, Lusis AJ. Genetic control of obesity and gut microbiota composition in response to high-fat, high-sucrose diet in mice. Cell Metab 2013; 17:141-52. [PMID: 23312289 PMCID: PMC3545283 DOI: 10.1016/j.cmet.2012.12.007] [Citation(s) in RCA: 386] [Impact Index Per Article: 35.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 11/05/2012] [Accepted: 12/12/2012] [Indexed: 12/16/2022]
Abstract
Obesity is a highly heritable disease driven by complex interactions between genetic and environmental factors. Human genome-wide association studies (GWAS) have identified a number of loci contributing to obesity; however, a major limitation of these studies is the inability to assess environmental interactions common to obesity. Using a systems genetics approach, we measured obesity traits, global gene expression, and gut microbiota composition in response to a high-fat/high-sucrose (HF/HS) diet of more than 100 inbred strains of mice. Here we show that HF/HS feeding promotes robust, strain-specific changes in obesity that are not accounted for by food intake and provide evidence for a genetically determined set point for obesity. GWAS analysis identified 11 genome-wide significant loci associated with obesity traits, several of which overlap with loci identified in human studies. We also show strong relationships between genotype and gut microbiota plasticity during HF/HS feeding and identify gut microbial phylotypes associated with obesity.
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Affiliation(s)
- Brian W Parks
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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7
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Kim JB, Deluna A, Mungrue IN, Vu C, Pouldar D, Civelek M, Orozco L, Wu J, Wang X, Charugundla S, Castellani LW, Rusek M, Jakubowski H, Jakobowski H, Lusis AJ. Effect of 9p21.3 coronary artery disease locus neighboring genes on atherosclerosis in mice. Circulation 2012; 126:1896-906. [PMID: 22952318 DOI: 10.1161/circulationaha.111.064881] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
BACKGROUND The human 9p21.3 chromosome locus has been shown to be an independent risk factor for atherosclerosis in multiple large-scale genome-wide association studies, but the underlying mechanism remains unknown. We set out to investigate the potential role of the 9p21.3 locus neighboring genes, including Mtap, the 2 isoforms of Cdkn2a, p16Ink4a and p19Arf, and Cdkn2b, in atherosclerosis using knockout mice models. METHODS AND RESULTS Gene-targeted mice for neighboring genes, including Mtap, Cdkn2a, p19Arf, and Cdkn2b, were each bred to mice carrying the human APO*E3 Leiden transgene that sensitizes the mice for atherosclerotic lesions through elevated plasma cholesterol. We found that the mice heterozygous for Mtap developed larger lesions compared with wild-type mice (49623±21650 versus 18899±9604 μm(2) per section [mean±SD]; P=0.01), with morphology similar to that of wild-type mice. The Mtap heterozygous mice demonstrated changes in metabolic and methylation profiles and CD4(+) cell counts. The Cdkn2a knockout mice had smaller lesions compared with wild-type and heterozygous mice, and there were no significant differences in lesion size in p19Arf and Cdkn2b mutants compared with wild type. We observed extensive, tissue-specific compensatory regulation of the Cdkn2a and Cdkn2b genes among the various knockout mice, making the effects on atherosclerosis difficult to interpret. CONCLUSIONS Mtap plays a protective role against atherosclerosis, whereas Cdkn2a appears to be modestly proatherogenic. However, no relation was found between the 9p21 genotype and the transcription of 9p21 neighboring genes in primary human aortic vascular cells in vitro. There is extensive compensatory regulation in the highly conserved 9p21 orthologous region in mice.
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Affiliation(s)
- Juyong Brian Kim
- Division of Cardiology, Department of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1679, USA
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8
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Wiltshire SA, Diez E, Miao Q, Dubé MP, Gagné M, Paquette O, Lafrenière RG, Ndao M, Castellani LW, Skamene E, Vidal SM, Fortin A. Genetic control of high density lipoprotein-cholesterol in AcB/BcA recombinant congenic strains of mice. Physiol Genomics 2012; 44:843-52. [PMID: 22805347 DOI: 10.1152/physiolgenomics.00025.2012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Epidemiological studies show that high HDL-cholesterol (HDLc) decreases the risk of cardiovascular disease. To map genes controlling lipid metabolism, particularly HDLc levels, we screened the plasma lipids of 36 AcB/BcA RC mouse strains subjected to either a normal or a high-fat/cholesterol diet. Strains BcA68 and AcB65 showed deviant HDLc plasma levels compared with the parental A/J and C57BL/6J strains; they were thus selected to generate informative F2 crosses. Linkage analyses in the AcB65 strain identified a locus on chromosome 4 (Hdlq78) responsible for high post-high fat diet HDLc levels. This locus has been previously associated at genome-wide significance to two regions in the human genome. A second linkage analysis in strain BcA68 identified linkage in the vicinity of a gene cluster known to control HDLc levels. Sequence analysis of these candidates identified a de novo, loss-of-function mutation in the ApoA1 gene of BcA68 that prematurely truncates the ApoA1 protein. The possibility of dissecting the specific effects of this new ApoA1 deficiency in the context of isogenic controls makes the BcA68 mouse a valuable new tool.
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Affiliation(s)
- Sean A Wiltshire
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
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9
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Hong C, Bradley MN, Rong X, Wang X, Wagner A, Grijalva V, Castellani LW, Salazar J, Realegeno S, Boyadjian R, Fogelman AM, Van Lenten BJ, Reddy ST, Lusis AJ, Tangirala RK, Tontonoz P. LXRα is uniquely required for maximal reverse cholesterol transport and atheroprotection in ApoE-deficient mice. J Lipid Res 2012; 53:1126-33. [PMID: 22454476 PMCID: PMC3351819 DOI: 10.1194/jlr.m022061] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The liver X receptor (LXR) signaling pathway is an important modulator of
atherosclerosis, but the relative importance of the two LXRs in atheroprotection is
incompletely understood. We show here that LXRα, the dominant LXR isotype
expressed in liver, plays a particularly important role in whole-body sterol
homeostasis. In the context of the ApoE−/− background,
deletion of LXRα, but not LXRβ, led to prominent increases in
atherosclerosis and peripheral cholesterol accumulation. However, combined loss of
LXRα and LXRβ on the ApoE−/− background led to an
even more severe cholesterol accumulation phenotype compared to
LXRα−/−ApoE−/− mice,
indicating that LXRβ does contribute to reverse cholesterol transport (RCT) but
that this contribution is quantitatively less important than that of LXRα.
Unexpectedly, macrophages did not appear to underlie the differential phenotype of
LXRα−/−ApoE−/− and
LXRβ−/−ApoE−/− mice, as in
vitro assays revealed no difference in the efficiency of cholesterol efflux from
isolated macrophages. By contrast, in vivo assays of RCT using exogenously labeled
macrophages revealed a marked defect in fecal sterol efflux in
LXRα−/−ApoE−/− mice.
Mechanistically, this defect was linked to a specific requirement for
LXRα−/− in the expression of hepatic LXR target genes
involved in sterol transport and metabolism. These studies reveal a previously
unrecognized requirement for hepatic LXRα for optimal reverse cholesterol
transport in mice.
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Affiliation(s)
- Cynthia Hong
- Howard Hughes Medical Institute, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
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10
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Davis RC, van Nas A, Castellani LW, Zhao Y, Zhou Z, Wen P, Yu S, Qi H, Rosales M, Schadt EE, Broman KW, Péterfy M, Lusis AJ. Systems genetics of susceptibility to obesity-induced diabetes in mice. Physiol Genomics 2011; 44:1-13. [PMID: 22010005 DOI: 10.1152/physiolgenomics.00003.2011] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Inbred strains of mice are strikingly different in susceptibility to obesity-driven diabetes. For instance, deficiency in leptin receptor (db/db) leads to hyperphagia and obesity in both C57BL/6 and DBA/2 mice, but only on the DBA/2 background do the mice develop beta-cell loss leading to severe diabetes, while C57BL/6 mice are relatively resistant. To further investigate the genetic factors predisposing to diabetes, we have studied leptin receptor-deficient offspring of an F2 cross between C57BL/6J (db/+) males and DBA/2J females. The results show that the genetics of diabetes susceptibility are enormously complex and a number of quantitative trait loci (QTL) contributing to diabetes-related traits were identified, notably on chromosomes 4, 6, 7, 9, 10, 11, 12, and 19. The Chr. 4 locus is likely due to a disruption of the Zfp69 gene in C57BL/6J mice. To identify candidate genes and to model coexpression networks, we performed global expression array analysis in livers of the F2 mice. Expression QTL (eQTL) were identified and used to prioritize candidate genes at clinical trait QTL. In several cases, clusters of eQTLs colocalized with clinical trait QTLs, suggesting a common genetic basis. We constructed coexpression networks for both 5 and 12 wk old mice and identified several modules significantly associated with clinical traits. One module in 12 wk old mice was associated with several measures of hepatic fat content as well as with other lipid- and diabetes-related traits. These results add to the understanding of the complex genetic interactions contributing to obesity-induced diabetes.
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Affiliation(s)
- Richard C Davis
- Department of Medicine, University of California, Los Angeles, California 90095-1679, USA.
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11
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Langfelder P, Castellani LW, Zhou Z, Paul E, Davis R, Schadt EE, Lusis AJ, Horvath S, Mehrabian M. A systems genetic analysis of high density lipoprotein metabolism and network preservation across mouse models. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:435-47. [PMID: 21807117 DOI: 10.1016/j.bbalip.2011.07.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 07/14/2011] [Accepted: 07/15/2011] [Indexed: 01/22/2023]
Abstract
We report a systems genetic analysis of high density lipoprotein (HDL) levels in an F2 intercross between inbred strains CAST/EiJ and C57BL/6J. We previously showed that there are dramatic differences in HDL metabolism in a cross between these strains, and we now report co-expression network analysis of HDL that integrates global expression data from liver and adipose with relevant metabolic traits. Using data from a total of 293 F2 intercross mice, we constructed weighted gene co-expression networks and identified modules (subnetworks) associated with HDL and clinical traits. These were examined for genes implicated in HDL levels based on large human genome-wide associations studies (GWAS) and examined with respect to conservation between tissue and sexes in a total of 9 data sets. We identify genes that are consistently ranked high by association with HDL across the 9 data sets. We focus in particular on two genes, Wfdc2 and Hdac3, that are located in close proximity to HDL QTL peaks where causal testing indicates that they may affect HDL. Our results provide a rich resource for studies of complex metabolic interactions involving HDL. This article is part of a Special Issue entitled Advances in High Density Lipoprotein Formation and Metabolism: A Tribute to John F. Oram (1945-2010).
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Affiliation(s)
- Peter Langfelder
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Gonda (Goldschmied) Neuroscience and Genetics Research Center, 695 Charles E. Young Drive South, Box 708822, Los Angeles, CA 90095-7088, USA.
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12
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Barajas B, Che N, Yin F, Rowshanrad A, Orozco LD, Gong KW, Wang X, Castellani LW, Reue K, Lusis AJ, Araujo JA. NF-E2-related factor 2 promotes atherosclerosis by effects on plasma lipoproteins and cholesterol transport that overshadow antioxidant protection. Arterioscler Thromb Vasc Biol 2010; 31:58-66. [PMID: 20947826 DOI: 10.1161/atvbaha.110.210906] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To test the hypothesis that NF-E2-related factor 2 (Nrf2) expression plays an antiatherogenic role by its vascular antioxidant and anti-inflammatory properties. METHODS AND RESULTS Nrf2 is an important transcription factor that regulates the expression of phase 2 detoxifying enzymes and antioxidant genes. Its expression in vascular cells appears to be an important factor in the protection against vascular oxidative stress and inflammation. We developed Nrf2 heterozygous (HET) and homozygous knockout (KO) mice on an apolipoprotein (apo) E-null background by sequential breeding, resulting in Nrf2(-/-), apoE(-/-) (KO), Nrf2(-/+), apoE(-/-) (HET) and Nrf2(+/+), and apoE(-/-) wild-type littermates. KO mice exhibited decreased levels of antioxidant genes with evidence of increased reactive oxygen species generation compared with wild-type controls. Surprisingly, KO males exhibited 47% and 53% reductions in the degree of aortic atherosclerosis compared with HET or wild-type littermates, respectively. Decreased atherosclerosis in KO mice correlated with lower plasma total cholesterol in a sex-dependent manner. KO mice also had a decreased hepatic cholesterol content and a lower expression of lipogenic genes, suggesting that hepatic lipogenesis could be reduced. In addition, KO mice exhibited atherosclerotic plaques characterized by a lesser macrophage component and decreased foam cell formation in an in vitro lipid-loading assay. This was associated with a lower rate of cholesterol influx, mediated in part by decreased expression of the scavenger receptor CD36. CONCLUSIONS Nrf2 expression unexpectedly promotes atherosclerotic lesion formation in a sex-dependent manner, most likely by a combination of systemic metabolic and local vascular effects.
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Affiliation(s)
- Berenice Barajas
- Department of Medicine, University of California, Center for Health Sciences, Los Angeles, CA 90095, USA
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13
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Davis RC, Castellani LW, Hosseini M, Ben-Zeev O, Mao HZ, Weinstein MM, Jung DY, Jun JY, Kim JK, Lusis AJ, Péterfy M. Early hepatic insulin resistance precedes the onset of diabetes in obese C57BLKS-db/db mice. Diabetes 2010; 59:1616-25. [PMID: 20393148 PMCID: PMC2889760 DOI: 10.2337/db09-0878] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
OBJECTIVE To identify metabolic derangements contributing to diabetes susceptibility in the leptin receptor-deficient obese C57BLKS/J-db/db (BKS-db) mouse strain. RESEARCH DESIGN AND METHODS Young BKS-db mice were used to identify metabolic pathways contributing to the development of diabetes. Using the diabetes-resistant B6-db strain as a comparison, in vivo and in vitro approaches were applied to identify metabolic and molecular differences between the two strains. RESULTS Despite higher plasma insulin levels, BKS-db mice exhibit lower lipogenic gene expression, rate of lipogenesis, hepatic triglyceride and glycogen content, and impaired insulin suppression of gluconeogenic genes. Hepatic insulin receptor substrate (IRS)-1 and IRS-2 expression and insulin-stimulated Akt-phosphorylation are decreased in BKS-db primary hepatocytes. Hyperinsulinemic-euglycemic clamp studies indicate that in contrast to hepatic insulin resistance, skeletal muscle is more insulin sensitive in BKS-db than in B6-db mice. We also demonstrate that elevated plasma triglyceride levels in BKS-db mice are associated with reduced triglyceride clearance due to lower lipase activities. CONCLUSIONS Our study demonstrates the presence of metabolic derangements in BKS-db before the onset of beta-cell failure and identifies early hepatic insulin resistance as a component of the BKS-db phenotype. We propose that defects in hepatic insulin signaling contribute to the development of diabetes in the BKS-db mouse strain.
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Affiliation(s)
- Richard C. Davis
- Department of Medicine, University of California, Los Angeles, Los Angeles, California
| | | | - Maryam Hosseini
- Department of Medicine, University of California, Los Angeles, Los Angeles, California
- Lipid Research Laboratory, VA Greater Los Angeles Healthcare System, Los Angeles, California
- Medical Genetics Institute, Cedars-Sinai Medical Center, Los Angeles, California
| | - Osnat Ben-Zeev
- Department of Medicine, University of California, Los Angeles, Los Angeles, California
- Lipid Research Laboratory, VA Greater Los Angeles Healthcare System, Los Angeles, California
| | - Hui Z. Mao
- Lipid Research Laboratory, VA Greater Los Angeles Healthcare System, Los Angeles, California
- Medical Genetics Institute, Cedars-Sinai Medical Center, Los Angeles, California
| | - Michael M. Weinstein
- Department of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Dae Young Jung
- Program in Molecular Medicine, Division of Endocrinology, Metabolism and Diabetes, University of Massachusetts Medical School, Worcester, Massachusetts
- Department of Cellular and Molecular Physiology, Pennsylvania State University School of Medicine, Hershey, Pennsylvania
| | - John Y. Jun
- Department of Cellular and Molecular Physiology, Pennsylvania State University School of Medicine, Hershey, Pennsylvania
| | - Jason K. Kim
- Program in Molecular Medicine, Division of Endocrinology, Metabolism and Diabetes, University of Massachusetts Medical School, Worcester, Massachusetts
- Department of Cellular and Molecular Physiology, Pennsylvania State University School of Medicine, Hershey, Pennsylvania
- Department of Medicine, Division of Endocrinology, Metabolism and Diabetes, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Aldons J. Lusis
- Department of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Miklós Péterfy
- Department of Medicine, University of California, Los Angeles, Los Angeles, California
- Lipid Research Laboratory, VA Greater Los Angeles Healthcare System, Los Angeles, California
- Medical Genetics Institute, Cedars-Sinai Medical Center, Los Angeles, California
- Corresponding author: Miklos Peterfy,
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14
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Woo JMP, Lin Z, Navab M, Van Dyck C, Trejo-Lopez Y, Woo KMT, Li H, Castellani LW, Wang X, Iikuni N, Rullo OJ, Wu H, La Cava A, Fogelman AM, Lusis AJ, Tsao BP. Treatment with apolipoprotein A-1 mimetic peptide reduces lupus-like manifestations in a murine lupus model of accelerated atherosclerosis. Arthritis Res Ther 2010; 12:R93. [PMID: 20482780 PMCID: PMC2911877 DOI: 10.1186/ar3020] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Revised: 04/26/2010] [Accepted: 05/18/2010] [Indexed: 11/10/2022] Open
Abstract
Introduction The purpose of this study was to evaluate the effects of L-4F, an apolipoprotein A-1 mimetic peptide, alone or with pravastatin, in apoE-/-Fas-/-C57BL/6 mice that spontaneously develop immunoglobulin G (IgG) autoantibodies, glomerulonephritis, osteopenia, and atherosclerotic lesions on a normal chow diet. Methods Female mice, starting at eight to nine weeks of age, were treated for 27 weeks with 1) pravastatin, 2) L-4F, 3) L-4F plus pravastatin, or 4) vehicle control, followed by disease phenotype assessment. Results In preliminary studies, dysfunctional, proinflammatory high-density lipoproteins (piHDL) were decreased six hours after a single L-4F, but not scrambled L-4F, injection in eight- to nine-week old mice. After 35 weeks, L-4F-treated mice, in the absence/presence of pravastatin, had significantly smaller lymph nodes and glomerular tufts (PL, LP < 0.05), lower serum levels of IgG antibodies to double stranded DNA (dsDNA) (PL < 0.05) and oxidized phospholipids (oxPLs) (PL, LP < 0.005), and elevated total and vertebral bone mineral density (PL, LP < 0.01) compared to vehicle controls. Although all treatment groups presented larger aortic root lesions compared to vehicle controls, enlarged atheromas in combination treatment mice had significantly less infiltrated CD68+ macrophages (PLP < 0.01), significantly increased mean α-actin stained area (PLP < 0.05), and significantly lower levels of circulating markers for atherosclerosis progression, CCL19 (PL, LP < 0.0005) and VCAM-1 (PL < 0.0002). Conclusions L-4F treatment, alone or with pravastatin, significantly reduced IgG anti-dsDNA and IgG anti-oxPLs, proteinuria, glomerulonephritis, and osteopenia in a murine lupus model of accelerated atherosclerosis. Despite enlarged aortic lesions, increased smooth muscle content, decreased macrophage infiltration, and decreased pro-atherogenic chemokines in L-4F plus pravastatin treated mice suggest protective mechanisms not only on lupus-like disease, but also on potential plaque remodeling in a murine model of systemic lupus erythematosus (SLE) and accelerated atherosclerosis.
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Affiliation(s)
- Jennifer M P Woo
- Department of Medicine-Rheumatology, David Geffen School of Medicine, University of California, 1000 Veteran Avenue, Los Angeles, CA 90095, USA
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15
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Bennett BJ, Farber CR, Orozco L, Kang HM, Ghazalpour A, Siemers N, Neubauer M, Neuhaus I, Yordanova R, Guan B, Truong A, Yang WP, He A, Kayne P, Gargalovic P, Kirchgessner T, Pan C, Castellani LW, Kostem E, Furlotte N, Drake TA, Eskin E, Lusis AJ. A high-resolution association mapping panel for the dissection of complex traits in mice. Genome Res 2010; 20:281-90. [PMID: 20054062 DOI: 10.1101/gr.099234.109] [Citation(s) in RCA: 252] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Systems genetics relies on common genetic variants to elucidate biologic networks contributing to complex disease-related phenotypes. Mice are ideal model organisms for such approaches, but linkage analysis has been only modestly successful due to low mapping resolution. Association analysis in mice has the potential of much better resolution, but it is confounded by population structure and inadequate power to map traits that explain less than 10% of the variance, typical of mouse quantitative trait loci (QTL). We report a novel strategy for association mapping that combines classic inbred strains for mapping resolution and recombinant inbred strains for mapping power. Using a mixed model algorithm to correct for population structure, we validate the approach by mapping over 2500 cis-expression QTL with a resolution an order of magnitude narrower than traditional QTL analysis. We also report the fine mapping of metabolic traits such as plasma lipids. This resource, termed the Hybrid Mouse Diversity Panel, makes possible the integration of multiple data sets and should prove useful for systems-based approaches to complex traits and studies of gene-by-environment interactions.
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Affiliation(s)
- Brian J Bennett
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
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16
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Wu S, Mar-Heyming R, Dugum EZ, Kolaitis NA, Qi H, Pajukanta P, Castellani LW, Lusis AJ, Drake TA. Upstream transcription factor 1 influences plasma lipid and metabolic traits in mice. Hum Mol Genet 2009; 19:597-608. [PMID: 19995791 DOI: 10.1093/hmg/ddp526] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Upstream transcription factor 1 (USF1) has been associated with familial combined hyperlipidemia, the metabolic syndrome, and related conditions, but the mechanisms involved are unknown. In this study, we report validation of Usf1 as a causal gene of cholesterol homeostasis, insulin sensitivity and body composition in mouse models using several complementary approaches and identify associated pathways and gene expression network modules. Over-expression of human USF1 in both transgenic mice and mice with transient liver-specific over-expression influenced metabolic trait phenotypes, including obesity, total cholesterol level, LDL/VLDL cholesterol and glucose/insulin ratio. Additional analyses of trait and hepatic gene expression data from an F2 population derived from C57BL/6J and C3H/HeJ strains in which there is a naturally occurring variation in Usf1 expression supported a causal role for Usf1 for relevant metabolic traits. Gene network and pathway analyses of the liver gene expression signatures in the F2 population and the hepatic over-expression model suggested the involvement of Usf1 in immune responses and metabolism, including an Igfbp2-centered module. In all three mouse model settings, notable sex specificity was observed, consistent with human studies showing differences in association with USF1 gene polymorphisms between sexes.
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Affiliation(s)
- Sulin Wu
- Department of Human Genetics, David Geffen School of Medicine at University of California, Los Angeles, CA 90095, USA
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17
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Weinstein MM, Yin L, Tu Y, Wang X, Wu X, Castellani LW, Walzem RL, Lusis AJ, Fong LG, Beigneux AP, Young SG. Chylomicronemia elicits atherosclerosis in mice--brief report. Arterioscler Thromb Vasc Biol 2009; 30:20-3. [PMID: 19815815 DOI: 10.1161/atvbaha.109.196329] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE The risk of atherosclerosis in the setting of chylomicronemia has been a topic of debate. In this study, we examined susceptibility to atherosclerosis in Gpihbp1-deficient mice (Gpihbp1(-/-)), which manifest severe chylomicronemia as a result of defective lipolysis. METHODS AND RESULTS Gpihbp1(-/-) mice on a chow diet have plasma triglyceride and cholesterol levels of 2812+/-209 and 319+/-27 mg/dL, respectively. Even though nearly all of the lipids were contained in large lipoproteins (50 to 135 nm), the mice developed progressive aortic atherosclerosis. In other experiments, we found that both Gpihbp1-deficient "apo-B48-only" mice and Gpihbp1-deficient "apo-B100-only" mice manifest severe chylomicronemia. Thus, GPIHBP1 is required for the processing of both apo-B48- and apo-B100-containing lipoproteins. CONCLUSIONS Chylomicronemia causes atherosclerosis in mice. Also, we found that GPIHBP1 is required for the lipolytic processing of both apo-B48- and apo-B100-containing lipoproteins.
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18
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Tu P, Bhasin S, Hruz PW, Herbst KL, Castellani LW, Hua N, Hamilton JA, Guo W. Genetic disruption of myostatin reduces the development of proatherogenic dyslipidemia and atherogenic lesions in Ldlr null mice. Diabetes 2009; 58:1739-48. [PMID: 19509018 PMCID: PMC2712781 DOI: 10.2337/db09-0349] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVE Insulin-resistant states, such as obesity and type 2 diabetes, contribute substantially to accelerated atherogenesis. Null mutations of myostatin (Mstn) are associated with increased muscle mass and decreased fat mass. In this study, we determined whether Mstn disruption could prevent the development of insulin resistance, proatherogenic dyslipidemia, and atherogenesis. RESEARCH DESIGN AND METHODS C57BL/6 Ldlr(-/-) mice were cross-bred with C57BL/6 Mstn(-/-) mice for >10 generations to generate Mstn(-/-)/Ldlr(-/-) double-knockout mice. The effects of high-fat/high-cholesterol diet on body composition, plasma lipids, systemic and tissue-specific insulin sensitivity, hepatic steatosis, as well as aortic atheromatous lesion were characterized in Mstn(-/-)/Ldlr(-/-) mice in comparison with control Mstn(+/+)/Ldlr(-/-) mice. RESULTS Compared with Mstn(+/+)/Ldlr(-/-) controls, Mstn(-/-)/ Ldlr(-/-) mice were resistant to diet-induced obesity, and had greatly improved insulin sensitivity, as indicated by 42% higher glucose infusion rate and 90% greater muscle [(3)H]-2-deoxyglucose uptake during hyperinsulinemic-euglycemic clamp. Mstn(-/-)/Ldlr(-/-) mice were protected against diet-induced hepatic steatosis and had 56% higher rate of hepatic fatty acid beta-oxidation than controls. Mstn(-/-)/Ldlr(-/-) mice also had 36% lower VLDL secretion rate and were protected against diet-induced dyslipidemia, as indicated by 30-60% lower VLDL and LDL cholesterol, free fatty acids, and triglycerides. Magnetic resonance angiography and en face analyses demonstrated 41% reduction in aortic atheromatous lesions in Ldlr(-/-) mice with Mstn deletion. CONCLUSIONS Inactivation of Mstn protects against the development of insulin resistance, proatherogenic dyslipidemia, and aortic atherogenesis in Ldlr(-/-) mice. Myostatin may be a useful target for drug development for prevention and treatment of obesity and its associated type 2 diabetes and atherosclerosis.
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Affiliation(s)
- Powen Tu
- Department of Molecular Medicine, Boston University School of Medicine, Boston, Massachusetts
| | - Shalender Bhasin
- Department of Molecular Medicine, Boston University School of Medicine, Boston, Massachusetts
- Section of Endocrinology, Diabetes, & Nutrition, Department of Medicine, Boston Medical Center, Boston, Massachusetts
- Corresponding author: Shalender Bhasin,
| | - Paul W. Hruz
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
| | - Karen L. Herbst
- Division of Endocrinology & Metabolism, University of California San Diego, San Diego, California
| | - Lawrence W. Castellani
- Departments of Medicine/Cardiology, University of California Los Angeles, Los Angeles, California
| | - Ning Hua
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts
| | - James A. Hamilton
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts
| | - Wen Guo
- Section of Endocrinology, Diabetes, & Nutrition, Department of Medicine, Boston Medical Center, Boston, Massachusetts
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19
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Cervino AC, Li G, Edwards S, Zhu J, Laurie C, Tokiwa G, Lum PY, Wang S, Castellani LW, Lusis AJ, Carlson S, Sachs AB, Schadt EE. Corrigendum to “Integrating QTL and high-density SNP analyses in mice to identify Insig2 as a susceptibility gene for plasma cholesterol levels” [Genomics 86 (2005) 505–517]. Genomics 2009. [DOI: 10.1016/j.ygeno.2008.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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20
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Yang X, Deignan JL, Qi H, Zhu J, Qian S, Zhong J, Torosyan G, Majid S, Falkard B, Kleinhanz RR, Karlsson J, Castellani LW, Mumick S, Wang K, Xie T, Coon M, Zhang C, Estrada-Smith D, Farber CR, Wang SS, van Nas A, Ghazalpour A, Zhang B, Macneil DJ, Lamb JR, Dipple KM, Reitman ML, Mehrabian M, Lum PY, Schadt EE, Lusis AJ, Drake TA. Validation of candidate causal genes for obesity that affect shared metabolic pathways and networks. Nat Genet 2009; 41:415-23. [PMID: 19270708 PMCID: PMC2837947 DOI: 10.1038/ng.325] [Citation(s) in RCA: 227] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2008] [Accepted: 01/13/2009] [Indexed: 02/06/2023]
Abstract
A major task in dissecting the genetics of complex traits is to identify causal genes for disease phenotypes. We previously developed a method to infer causal relationships among genes through the integration of DNA variation, gene transcription, and phenotypic information. Here we validated our method through the characterization of transgenic and knockout mouse models of candidate genes that were predicted to be causal for abdominal obesity. Perturbation of eight out of the nine genes, with Gas7, Me1 and Gpx3 being novel, resulted in significant changes in obesity related traits. Liver expression signatures revealed alterations in common metabolic pathways and networks contributing to abdominal obesity and overlapped with a macrophage-enriched metabolic network module that is highly associated with metabolic traits in mice and humans. Integration of gene expression in the design and analysis of traditional F2 intercross studies allows high confidence prediction of causal genes and identification of involved pathways and networks.
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Affiliation(s)
- Xia Yang
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
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21
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Vaessen SFC, Dallinga-Thie GM, Ross CJD, Splint LJ, Castellani LW, Rensen PCN, Hayden MR, Schaap FG, Kuivenhoven JA. Plasma apolipoprotein AV levels in mice are positively associated with plasma triglyceride levels. J Lipid Res 2009; 50:880-4. [PMID: 19141870 DOI: 10.1194/jlr.m800551-jlr200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Apolipoprotein AV (apoAV) overexpression causes a decrease in plasma triglyceride (TG) levels, while deficiency of apoAV causes hypertriglyceridemia in both men and mice. However, contrary to what would be expected, plasma apoAV and TG levels in humans are positively correlated. To address this apparent paradox, we determined plasma apoAV levels in various mouse models with median TG levels ranging from 30 mg/dl in wild-type mice to 2089 mg/dl in glycosylphosphatidylinositol-anchored HDL binding protein 1-deficient mice. The data show that apoAV and TG levels are positively correlated in mice (r = +0.798, P < 0.001). In addition, we show that LPL gene transfer caused a simultaneous decrease in TG and apoAV in LPL-deficient mice. The combined data suggest that apoAV levels follow TG levels due to an intimate link between the apoAV molecule and TG-rich lipoproteins, comprising both secretion and removal of these lipoproteins. Taken together, the data suggest that higher plasma apoAV levels reflect an increased demand for plasma TG hydrolysis under normal physiological conditions.
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Affiliation(s)
- S F C Vaessen
- Department of Vascular Medicine, Academic Medical Center, Amsterdam, The Netherlands
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22
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Mehrabian M, Schulthess FT, Nebohacova M, Castellani LW, Zhou Z, Hartiala J, Oberholzer J, Lusis AJ, Maedler K, Allayee H. Identification of ALOX5 as a gene regulating adiposity and pancreatic function. Diabetologia 2008; 51:978-88. [PMID: 18421434 PMCID: PMC2835627 DOI: 10.1007/s00125-008-1002-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Accepted: 02/08/2008] [Indexed: 11/27/2022]
Abstract
AIMS/HYPOTHESIS We previously used an integrative genetics approach to demonstrate that 5-lipoxygenase (5-LO) deficiency in mice (Alox5 (-/-)) protects against atherosclerosis despite increasing lipid levels and fat mass. In the present study, we sought to further examine the role of 5-LO in adiposity and pancreatic function. METHODS Alox5 (-/-) and wild-type (WT) mice were characterised with respect to adiposity and glucose/insulin metabolism using in vivo and in vitro approaches. The role of ALOX5 in pancreatic function in human islets was assessed through short interfering RNA (siRNA) knockdown experiments. RESULTS Beginning at 12 weeks of age, Alox5 (-/-) mice had significantly increased fat mass, plasma leptin levels and fasting glucose levels, but lower fasting insulin levels (p<0.05). Although Alox5 (-/-) mice did not exhibit insulin resistance, they had impaired insulin secretion in response to a bolus glucose injection. Histological analyses revealed that Alox5 (-/-) mice had increased islet area, beta cell nuclear size, and numbers of beta cells/mm(2) islet (p<0.05), indicative of both hyperplasia and hypertrophy. Basal and stimulated insulin secretion in isolated Alox5 (-/-) islets were significantly lower than in WT islets (p<0.05) and accompanied by a three- to fivefold decrease in the expression of the genes encoding insulin and pancreatic duodenal homeobox 1 (Pdx1). Direct perturbation of ALOX5 in isolated human islets with siRNA decreased insulin and PDX1 gene expression by 50% and insulin secretion by threefold (p<0.05). CONCLUSIONS/INTERPRETATION These results provide strong evidence for pleiotropic metabolic effects of 5-LO on adiposity and pancreatic function and may have important implications for therapeutic strategies targeting this pathway for the treatment of cardiovascular disease.
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Affiliation(s)
- M Mehrabian
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
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23
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Sauter NS, Schulthess FT, Galasso R, Castellani LW, Maedler K. The antiinflammatory cytokine interleukin-1 receptor antagonist protects from high-fat diet-induced hyperglycemia. Endocrinology 2008; 149:2208-18. [PMID: 18239070 PMCID: PMC2734491 DOI: 10.1210/en.2007-1059] [Citation(s) in RCA: 154] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Subclinical inflammation is a recently discovered phenomenon in type 2 diabetes. Elevated cytokines impair beta-cell function and survival. A recent clinical trial shows that blocking IL-1beta signaling by IL-1 receptor antagonist (IL-1Ra) improves beta-cell secretory function in patients with type 2 diabetes. In the present study, we provide further mechanisms of the protective role of IL-1Ra on the beta-cell. IL-1Ra prevented diabetes in vivo in C57BL/6J mice fed a high-fat/high-sucrose diet (HFD) for 12 wk; it improved glucose tolerance and insulin secretion. High-fat diet treatment increased serum levels of free fatty acids and of the adipokines resistin and leptin, which were reduced by IL-1Ra treatment. In addition, IL-1Ra counteracted adiponectin levels, which were decreased by high-fat feeding. Studies on isolated islets revealed that IL-1Ra specifically acted on the beta-cell. IL-1Ra protected islets from HFD treated animals from beta-cell apoptosis, induced beta-cell proliferation, and improved glucose-stimulated insulin secretion. Insulin mRNA was reduced in islets from mice fed a HFD but normalized in the IL-1Ra group. Our results show that IL-1Ra improves beta-cell survival and function, and support the potential role for IL-1Ra in the treatment of diabetes.
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Affiliation(s)
- Nadine S Sauter
- Larry L. Hillblom Islet Research Center, University of California Los Angeles, Los Angeles, California 90095-7345, USA
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24
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Castellani LW, Nguyen CN, Charugundla S, Weinstein MM, Doan CX, Blaner WS, Wongsiriroj N, Lusis AJ. Apolipoprotein AII is a regulator of very low density lipoprotein metabolism and insulin resistance. J Biol Chem 2007; 283:11633-44. [PMID: 18160395 DOI: 10.1074/jbc.m708995200] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Apolipoprotein AII (apoAII) transgenic (apoAIItg) mice exhibit several traits associated with the insulin resistance (IR) syndrome, including IR, obesity, and a marked hypertriglyceridemia. Because treatment of the apoAIItg mice with rosiglitazone ameliorated the IR and hypertriglyceridemia, we hypothesized that the hypertriglyceridemia was due largely to overproduction of very low density lipoprotein (VLDL) by the liver, a normal response to chronically elevated insulin and glucose. We now report in vivo and in vitro studies that indicate that hepatic fatty acid oxidation was reduced and lipogenesis increased, resulting in a 25% increase in triglyceride secretion in the apoAIItg mice. In addition, we observed that hydrolysis of triglycerides from both chylomicrons and VLDL was significantly reduced in the apoAIItg mice, further contributing to the hypertriglyceridemia. This is a direct, acute effect, because when mouse apoAII was injected into mice, plasma triglyceride concentrations were significantly increased within 4 h. VLDL from both control and apoAIItg mice contained significant amounts of apoAII, with approximately 4 times more apoAII on apoAIItg VLDL. ApoAII was shown to transfer spontaneously from high density lipoprotein (HDL) to VLDL in vitro, resulting in VLDL that was a poorer substrate for hydrolysis by lipoprotein lipase. These results indicate that one function of apoAII is to regulate the metabolism of triglyceride-rich lipoproteins, with HDL serving as a plasma reservoir of apoAII that is transferred to the triglyceride-rich lipoproteins in much the same way as VLDL and chylomicrons acquire most of their apoCs from HDL.
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Affiliation(s)
- Lawrence W Castellani
- Departments of Medicine/Cardiology University of California, Los Angeles, Los Angeles, California 90095, USA.
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25
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Feng X, Li H, Rumbin AA, Wang X, La Cava A, Brechtelsbauer K, Castellani LW, Witztum JL, Lusis AJ, Tsao BP. ApoE-/-Fas-/- C57BL/6 mice: a novel murine model simultaneously exhibits lupus nephritis, atherosclerosis, and osteopenia. J Lipid Res 2007; 48:794-805. [PMID: 17259598 DOI: 10.1194/jlr.m600512-jlr200] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To establish a mouse model of accelerated atherosclerosis in lupus, we generated apolipoprotein E-deficient (apoE(-/-)) and Fas(lpr/lpr) (Fas(-/-)) C57BL/6 mice. On a normal chow diet, 5 month old apoE(-/-)Fas(-/-) mice had enlarged glomerular tuft areas, severe proteinuria, increased circulating autoantibody levels, and increased apoptotic cells in renal and vascular lesions compared with either single knockout mice. Also, double knockout mice developed increased atherosclerotic lesions but decreased serum levels of total and non-HDL cholesterol compared with apoE(-/-)Fas(+/+) littermates. Moreover, female apoE(-/-)Fas(-/-) mice had lower vertebral bone mineral density (BMD) and bone volume density (BV/TV) than age-matched female apoE(-/-)Fas(+/+) mice. Compared with apoE(-/-)Fas(+/+) and apoE(+/+)Fas(-/-) mice, apoE(-/-)Fas(-/-) mice had decreased circulating oxidized phospholipid (OxPL) content on apoB-100 containing lipoprotein particles and increased serum IgG antibodies to OxPL, which were significantly correlated with aortic lesion areas (r = 0.58), glomerular tuft areas (r = 0.87), BMD (r = -0.57), and BV/TV (r = -0.72). These results suggest that the apoE(-/-)Fas(-/-) mouse model might be used to study atherosclerosis and osteopenia in lupus. Correlations of IgG anti-OxPL with lupus-like disease, atherosclerosis, and bone loss suggested a shared pathway of these disease processes.
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Affiliation(s)
- Xuebing Feng
- Division of Rheumatology, Department of Medicine, University of California, Los Angeles, CA, USA
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26
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Puppione DL, Yam LM, Bassilian S, Souda P, Castellani LW, Schumaker VN, Whitelegge JP. Mass spectral analysis of the apolipoproteins on mouse high density lipoproteins. Detection of post-translational modifications. Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics 2006; 1764:1363-71. [PMID: 16876491 DOI: 10.1016/j.bbapap.2006.06.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Revised: 05/15/2006] [Accepted: 06/07/2006] [Indexed: 10/24/2022]
Abstract
Using mass spectrometry, we have recently reported on molecular masses of the apolipoproteins associated with porcine and equine HDL. In addition to obtaining accurate masses for the various apolipoproteins, we also were able to detect mass variations due to post-translational modifications. In the present study, we have used these same approaches to characterize the apolipoproteins in two inbred mouse strains, C57BL/6 and BALB/c. Comparing our molecular mass data with calculated values for molecular weight, we were able to identify the correct sequences for several of the major apolipoproteins. Analyses were carried out on the apolipoproteins of ultracentrifugally isolated HDL. Prior to analyses by electrospray ionization mass spectrometry (ESI-MS), the apolipoproteins were separated either by size exclusion or reverse phase chromatography. The molecular masses of apoA-I, proapoA-I, apoA-II, proapoA-II, apoC-I and apoC-III were obtained. Comparing the values obtained for the two strains, differences in the molecular masses of apoA-I, apoA-II and apoC-III were observed. In this study, post-translationally modified apolipoproteins, involving loss of amino acids from both the N- and C-termini, oxidation of methionine residues and possible acylation, were noted following reverse-phase separation. Further analyses by tandem mass spectrometry (MSMS) done on the tryptic digests of apolipoproteins separated by reverse phase chromatography enabled us to confirm sequence differences between the two strains, to verify selected apoA-I sequences that had been entered into the GenBank and to identify which methionines in apoA-I, apoC-III and apoE had been converted to methionine sulfoxides.
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Affiliation(s)
- Donald L Puppione
- The Molecular Biology Institute and The Department of Chemistry and Biochemistry, University of California at Los Angeles, Los Angeles, CA 90095, USA.
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27
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Castellani LW, Chang JJ, Wang X, Lusis AJ, Reynolds WF. Transgenic mice express human MPO −463G/A alleles at atherosclerotic lesions, developing hyperlipidemia and obesity in −463G males. J Lipid Res 2006; 47:1366-77. [PMID: 16639078 DOI: 10.1194/jlr.m600005-jlr200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Myeloperoxidase (MPO) is an oxidant-generating enzyme present in macrophages at atherosclerotic lesions and implicated in coronary artery disease (CAD). Although mouse models are important for investigating the role of MPO in atherosclerosis, neither mouse MPO nor its oxidation products are detected in lesions in murine models. To circumvent this problem, we generated transgenic mice expressing two functionally different human MPO alleles, with either G or A at position -463, and crossed these to the LDL receptor-deficient (LDLR(-/-)) mouse. The -463G allele is linked to higher MPO expression and increased CAD incidence in humans. Both MPO alleles were expressed in a subset of lesions in high-fat-fed LDLR(-/-) mice, notably at necrotic lesions with cholesterol clefts. MPOG-expressing LDLR(-/-) males (but not females) developed significantly higher serum cholesterol, triglycerides, and glucose, all correlating with increased weight gain/obesity, implicating MPO in lipid homeostasis. The MPOG- and MPOA-expressing LDLR(-/-) males also exhibited significantly larger aortic lesions than control LDLR(-/-) males. The human MPO transgenic model will facilitate studies of MPO involvement in atherosclerosis and lipid homeostasis.
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Mehrabian M, Allayee H, Stockton J, Lum PY, Drake TA, Castellani LW, Suh M, Armour C, Edwards S, Lamb J, Lusis AJ, Schadt EE. Erratum: Integrating genotypic and expression data in a segregating mouse population to identify 5-lipoxygenase as a susceptibility gene for obesity and bone traits. Nat Genet 2005. [DOI: 10.1038/ng1205-1381a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Cervino AC, Li G, Edwards S, Zhu J, Laurie C, Tokiwa G, Lum PY, Wang S, Castellani LW, Castellini LW, Lusis AJ, Carlson S, Sachs AB, Schadt EE. Integrating QTL and high-density SNP analyses in mice to identify Insig2 as a susceptibility gene for plasma cholesterol levels. Genomics 2005; 86:505-17. [PMID: 16126366 DOI: 10.1016/j.ygeno.2005.07.010] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2005] [Accepted: 07/25/2005] [Indexed: 02/07/2023]
Abstract
The use of inbred strains of mice to dissect the genetic complexity of common diseases offers a viable alternative to human studies, given the control over experimental parameters that can be exercised. Central to efforts to map susceptibility loci for common diseases in mice is a comprehensive map of DNA variation among the common inbred strains of mice. Here we present one of the most comprehensive high-density, single nucleotide polymorphism (SNP) maps of mice constructed to date. This map consists of 10,350 SNPs genotyped in 62 strains of inbred mice. We demonstrate the utility of these data via a novel integrative genomics approach to mapping susceptibility loci for complex traits. By integrating in silico quantitative trait locus (QTL) mapping with progressive QTL mapping strategies in segregating mouse populations that leverage large-scale mapping of the genetic determinants of gene expression traits, we not only facilitate identification of candidate quantitative trait genes, but also protect against spurious associations that can arise in genetic association studies due to allelic association among unlinked markers. Application of this approach to our high-density SNP map and two previously described F2 crosses between strains C57BL/6J (B6) and DBA/2J and between B6 ApoE(-/-) and C3H/HeJ ApoE(-/-) results in the identification of Insig2 as a strong candidate susceptibility gene for total plasma cholesterol levels.
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Mehrabian M, Allayee H, Stockton J, Lum PY, Drake TA, Castellani LW, Suh M, Armour C, Edwards S, Lamb J, Lusis AJ, Schadt EE. Integrating genotypic and expression data in a segregating mouse population to identify 5-lipoxygenase as a susceptibility gene for obesity and bone traits. Nat Genet 2005; 37:1224-33. [PMID: 16200066 DOI: 10.1038/ng1619] [Citation(s) in RCA: 182] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2005] [Accepted: 06/21/2005] [Indexed: 11/08/2022]
Abstract
Forward genetic approaches to identify genes involved in complex traits such as common human diseases have met with limited success. Fine mapping of linkage regions and validation of positional candidates are time-consuming and not always successful. Here we detail a hybrid procedure to map loci involved in complex traits that leverages the strengths of forward and reverse genetic approaches. By integrating genotypic and expression data in a segregating mouse population, we show how clusters of expression quantitative trait loci linking to regions of the genome accurately reflect the underlying perturbation to the transcriptional network induced by DNA variations in genes that control the complex traits. By matching patterns of gene expression in a segregating population with expression responses induced by single-gene perturbation experiments, we show how genes controlling clusters of expression and clinical quantitative trait loci can be mapped directly. We demonstrate the utility of this approach by identifying 5-lipoxygenase as underlying previously identified quantitative trait loci in an F(2) cross between strains C57BL/6J and DBA/2J and showing that it has pleiotropic effects on body fat, lipid levels and bone density.
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Affiliation(s)
- Margarete Mehrabian
- Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California 90095-1679, USA
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Goodarzi MO, Wong H, Quiñones MJ, Taylor KD, Guo X, Castellani LW, Antoine HJ, Yang H, Hsueh WA, Rotter JI. The 3' untranslated region of the lipoprotein lipase gene: haplotype structure and association with post-heparin plasma lipase activity. J Clin Endocrinol Metab 2005; 90:4816-23. [PMID: 15928243 DOI: 10.1210/jc.2005-0389] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
CONTEXT Haplotypes comprising six single nucleotide polymorphisms (SNPs) (intron 7 to intron 9) of the lipoprotein lipase (LPL) gene appear to influence risk for atherosclerosis and insulin resistance in Mexican-Americans. OBJECTIVE Based on rodent studies, we hypothesized that these haplotypes are in linkage disequilibrium with functional variants in the 3' untranslated region of LPL, which is encoded by exon 10, and that these variants influence phenotype by altering LPL expression. DESIGN We sequenced exon 10 in subjects with divergent insulin sensitivity and divergent haplotypes. We also sequenced the other common LPL haplotypes. Variants identified by sequencing were genotyped in a large, family-based population along with the six SNPs spanning intron 7 to intron 9. We tested the potential functional significance of variation in exon 10 by evaluating association of haplotypes with post-heparin plasma LPL activity. SETTING The study took place within the general community, with the Mexican-American Coronary Artery Disease Project cohort. PARTICIPANTS Participants included 847 subjects from 163 families. MAIN OUTCOME MEASURES We determined LPL haplogenotype and post-heparin plasma LPL activity. RESULTS Exon 10 sequencing identified 15 variants. Thirteen of these variants were genotyped in large-scale along with the six SNPs spanning intron 7 to intron 9. LPL haplotypes and their relative frequencies in Mexican-Americans were determined. The fourth most common haplotype based on 19 SNPs (haplotype 19-4) was associated with increased LPL activity as well as multiple phenotypes related to the metabolic syndrome. CONCLUSIONS These results support the possibility that variation in the 3' untranslated region of LPL affects LPL expression and activity, consequently influencing risk of atherosclerosis and insulin resistance, and provides important tools for further dissection of LPL regulation.
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Affiliation(s)
- Mark O Goodarzi
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Cedars-Sinai Medical Center, 8700 Beverly Boulevard., Becker B-128, Los Angeles, California 90048, USA.
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Sheth SS, Castellani LW, Chari S, Wagg C, Thipphavong CK, Bodnar JS, Tontonoz P, Attie AD, Lopaschuk GD, Lusis AJ. Thioredoxin-interacting protein deficiency disrupts the fasting-feeding metabolic transition. J Lipid Res 2005; 46:123-34. [PMID: 15520447 DOI: 10.1194/jlr.m400341-jlr200] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Through a positional cloning approach, the thioredoxin-interacting protein gene (Txnip) was recently identified as causal for a form of combined hyperlipidemia in mice (Bodnar, J. S., A. Chatterjee, L. W. Castellani, D. A. Ross, J. Ohmen, J. Cavalcoli, C. Wu, K. M. Dains, J. Catanese, M. Chu, S. S. Sheth, K. Charugundla, P. Demant, D. B. West, P. de Jong, and A. J. Lusis. 2002. Positional cloning of the combined hyperlipidemia gene Hyplip1. Nat. Genet. 30: 110-116). We now show that Txnip-deficient mice in the fed state exhibit a metabolic profile similar to fasted mice, including increased levels of plasma ketone bodies and free fatty acids, decreased glucose, and increased hepatic expression of peroxisome proliferator-activated receptor-gamma coactivator-1alpha, phosphoenolpyruvate carboxykinase, glucose-6-phosphatase, and acyl-CoA oxidase. Dramatic differences in the expression of key metabolic enzymes were also observed in other tissues, and the fat-to-muscle ratio of Txnip-deficient mice was increased by approximately 40%. We demonstrate an effect of Txnip on the redox status, as the Txnip-deficient mice in the fed state had a significant increase in the ratio of NADH to NAD(+). Surprisingly, we observed that Txnip-deficient mice and wild-type mice had similar levels of thioredoxin activity, suggesting that the effects of Txnip deficiency may be mediated in part by other interactions. These results indicate a role for Txnip in the metabolic response to feeding and the maintenance of the redox status.
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Affiliation(s)
- Sonal S Sheth
- Department of Human Genetics, Medicine, Molecular Biology Institute, University of California, Los Angeles, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
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Wang X, Gargalovic P, Wong J, Gu JL, Wu X, Qi H, Wen P, Xi L, Tan B, Gogliotti R, Castellani LW, Chatterjee A, Lusis AJ. Hyplip2, a New Gene for Combined Hyperlipidemia and Increased Atherosclerosis. Arterioscler Thromb Vasc Biol 2004; 24:1928-34. [PMID: 15331434 DOI: 10.1161/01.atv.0000143385.30354.bb] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE We previously reported the mapping of a quantitative trait locus (QTL) on chromosome 15 contributing to hyperlipidemia in a cross between inbred strains MRL/MpJ (MRL) and BALB/cJ (BALB). Using marker-assisted breeding, we constructed a congenic strain in which chromosome 15 interval from MRL is placed on the genetic background of BALB. The congenic allowed us to confirm the QTL result and to further characterize the properties and location of the underlying gene. METHODS AND RESULTS On chow and high-fat (atherogenic) diets, the congenic mice exhibited higher levels of plasma triglycerides and cholesterol than BALB mice. In response to the atherogenic diet, the congenic mice but not BALB mice exhibited a dramatic approximately 30-fold increase in atherogenic lesions accompanied by approximately 2-fold decrease in high-density lipoprotein cholesterol levels. With respect to atherosclerotic lesions and some lipid parameters, this chromosome 15 gene, designated Hyplip2, exhibited dominant inheritance. Expression array analyses suggested that Hyplip2 may influence inflammatory and bile acid synthesis pathways. Finally, we demonstrated the usefulness of subcongenic strains to narrow the locus (50 Mbp) with the goal of positionally cloning Hyplip2. CONCLUSIONS Our data demonstrate that the Hyplip2 gene significantly contributes to combined hyperlipidemia and increased atherosclerosis in mice.
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Affiliation(s)
- Xuping Wang
- Department of Medicine,University of California, Los Angeles 90095-1679, USA
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Castellani LW, Gargalovic P, Febbraio M, Charugundla S, Jien ML, Lusis AJ. Mechanisms mediating insulin resistance in transgenic mice overexpressing mouse apolipoprotein A-II. J Lipid Res 2004; 45:2377-87. [PMID: 15466364 DOI: 10.1194/jlr.m400345-jlr200] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We previously demonstrated that transgenic mice overexpressing mouse apolipoprotein A-II (apoA-II) exhibit several traits associated with the insulin resistance (IR) syndrome, including increased atherosclerosis, hypertriglyceridemia, obesity, and IR. The skeletal muscle appeared to be the insulin-resistant tissue in the apoA-II transgenic mice. We now demonstrate a decrease in FA oxidation in skeletal muscle of apoA-II transgenic mice, consistent with reports that decreased skeletal muscle FA oxidation is associated with increased skeletal muscle triglyceride accumulation, skeletal muscle IR, and obesity. The decrease in FA oxidation is not due to decreased carnitine palmitoyltransferase 1 activity, because oxidation of palmitate and octanoate were similarly decreased. Quantitative RT-PCR analysis of gene expression demonstrated that the decrease in FA oxidation may be explained by a decrease in medium chain acyl-CoA dehydrogenase. We previously demonstrated that HDLs from apoA-II transgenic mice exhibit reduced binding to CD36, a scavenger receptor involved in FA metabolism. However, studies of combined apoA-II transgenic and CD36 knockout mice suggest that the major effects of apoA-II are independent of CD36. Rosiglitazone treatment significantly ameliorated IR in the apoA-II transgenic mice, suggesting that the underlying mechanisms of IR in this animal model may share common features with certain types of human IR.
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Affiliation(s)
- Lawrence W Castellani
- Department of Medicine, 47-123 CHS, University of California, Los Angeles, CA 90095, USA.
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Quiñones MJ, Hernandez-Pampaloni M, Schelbert H, Bulnes-Enriquez I, Jimenez X, Hernandez G, De La Rosa R, Chon Y, Yang H, Nicholas SB, Modilevsky T, Yu K, Van Herle K, Castellani LW, Elashoff R, Hsueh WA. Coronary vasomotor abnormalities in insulin-resistant individuals. Ann Intern Med 2004; 140:700-8. [PMID: 15126253 DOI: 10.7326/0003-4819-140-9-200405040-00009] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Insulin resistance is a metabolic spectrum that progresses from hyperinsulinemia to the metabolic syndrome, impaired glucose tolerance, and finally type 2 diabetes mellitus. It is unclear when vascular abnormalities begin in this spectrum of metabolic effects. OBJECTIVE To evaluate the association of insulin resistance with the presence and reversibility of coronary vasomotor abnormalities in young adults at low cardiovascular risk. DESIGN Cross-sectional study followed by prospective, open-label treatment study. SETTING University hospital. PATIENTS 50 insulin-resistant and 22 insulin-sensitive, age-matched Mexican-American participants without glucose intolerance or traditional risk factors for or evidence of coronary artery disease. INTERVENTION 3 months of thiazolidinedione therapy for 25 insulin-resistant patients. MEASUREMENTS Glucose infusion rate in response to insulin infusion was used to define insulin resistance (glucose infusion rate < or = 4.00 mg/kg of body weight per minute [range, 0.90 to 3.96 mg/kg per minute]) and insulin sensitivity (glucose infusion rate > or = 7.50 mg/kg per minute [range, 7.52 to 13.92 mg/kg per minute]). Myocardial blood flow was measured by using positron emission tomography at rest, during cold pressor test (largely endothelium-dependent), and after dipyridamole administration (largely vascular smooth muscle-dependent). RESULTS Myocardial blood flow responses to dipyridamole were similar in the insulin-sensitive and insulin-resistant groups. However, myocardial blood flow response to cold pressor test increased by 47.6% from resting values in insulin-sensitive patients and by 14.4% in insulin-resistant patients. During thiazolidinedione therapy in a subgroup of insulin-resistant patients, insulin sensitivity improved, fasting plasma insulin levels decreased, and myocardial blood flow responses to cold pressor test normalized. LIMITATIONS The study was not randomized, and it included only 1 ethnic group. CONCLUSIONS Insulin-resistant patients who do not have hypercholesterolemia or hypertension and do not smoke manifest coronary vasomotor abnormalities. Insulin-sensitizing thiazolidinedione therapy normalized these abnormalities. These results suggest an association between insulin resistance and abnormal coronary vasomotor function, a relationship that requires confirmation in larger studies.
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Affiliation(s)
- Manuel J Quiñones
- Division of Endocrinology, Diabetes and Hypertension, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, California 90095, USA
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Shi W, Wang X, Wong J, Hedrick CC, Wong H, Castellani LW, Lusis AJ. Effect of macrophage-derived apolipoprotein E on hyperlipidemia and atherosclerosis of LDLR-deficient mice. Biochem Biophys Res Commun 2004; 317:223-9. [PMID: 15047172 DOI: 10.1016/j.bbrc.2004.03.037] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2004] [Indexed: 10/26/2022]
Abstract
LDL receptor-deficient (LDLR(-/-)) mice fed a Western diet exhibit severe hyperlipidemia and develop significant atherosclerosis. Apolipoprotein E (apoE) is a multifunctional protein synthesized by hepatocytes and macrophages. We sought to determine effect of macrophage apoE deficiency on severe hyperlipidemia and atherosclerosis. Female LDLR(-/-) mice were lethally irradiated and reconstituted with bone marrow from either apoE(-/-) or apoE(+/+) mice. Four weeks after transplantation, recipient mice were fed a Western diet for 8 weeks. Reconstitution of LDLR(-/-) mice with apoE(-/-) bone marrow resulted in a slight reduction in plasma apoE levels and a dramatic reduction in accumulation of apoE and apoB in the aortic wall. Plasma lipid levels were unaffected when mice had mild hyperlipidemia on a chow diet, whereas IDL/LDL cholesterol levels were significantly reduced when mice developed severe hyperlipidemia on the Western diet. The hepatic VLDL production rate of mice on the Western diet was decreased by 46% as determined by injection of Triton WR1339 to block VLDL clearance. Atherosclerotic lesions in the proximal aorta were significantly reduced, partially due to reduction in plasma total cholesterol levels (r=0.56; P<0.0001). Thus, macrophage apoE-deficiency alleviates severe hyperlipidemia by slowing hepatic VLDL production and consequently reduces atherosclerosis in LDLR(-/-) mice.
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Affiliation(s)
- Weibin Shi
- Department of Radiology, University of Virginia, Charlottesville 22908, USA.
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Dhar MS, Sommardahl CS, Kirkland T, Nelson S, Donnell R, Johnson DK, Castellani LW. Mice heterozygous for Atp10c, a putative amphipath, represent a novel model of obesity and type 2 diabetes. J Nutr 2004; 134:799-805. [PMID: 15051828 DOI: 10.1093/jn/134.4.799] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Atp10c is a novel type IV P-type ATPase and is a putative phospholipid transporter. The purpose of this study was to assess the overall effect of the heterozygous deletion of Atp10c on obesity-related phenotypes and metabolic abnormalities in mice fed a high-fat diet. Heterozygous mice with maternal inheritance of Atp10c were compared with heterozygous mice with paternal inheritance of Atp10c and wild-type controls. Body weight, adiposity index, and plasma insulin, leptin and triglyceride concentrations were significantly greater in the mutants inheriting the deletion maternally compared with their sex- and age-matched control male mice fed a 10% fat (% energy) diet and female mice fed a 45% fat (% energy) diet. Glucose and insulin tolerance tests were performed after mice consumed the diets for 4 and 8 wk. Mutants had altered glucose tolerance and insulin response compared with controls, suggesting insulin resistance in both sexes. Mice were killed at 12 wk and routine gross and histological evaluations of the liver, pancreas, adipose tissue, and heart were performed. Histological evaluation showed micro- and macrovesicular lipid deposition within the hepatocytes that was more severe in the mutant mice than in age-matched controls. Although sex differences were observed, our data suggest that heterozygous deletion along with an unusual pattern of maternal inheritance of the chromosomal region containing the single gene, Atp10c, causes obesity, type 2 diabetes, and nonalcoholic fatty liver disease in these mice.
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Affiliation(s)
- Madhu S Dhar
- Department of Nutrition, University of Tennessee, Knoxville, TN 37996, USA.
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Zhang Y, Castellani LW, Sinal CJ, Gonzalez FJ, Edwards PA. Peroxisome proliferator-activated receptor-gamma coactivator 1alpha (PGC-1alpha) regulates triglyceride metabolism by activation of the nuclear receptor FXR. Genes Dev 2004; 18:157-69. [PMID: 14729567 PMCID: PMC324422 DOI: 10.1101/gad.1138104] [Citation(s) in RCA: 277] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Peroxisome proliferator-activated receptor-gamma coactivator 1alpha (PGC-1alpha) has been shown to regulate adaptive thermogenesis and glucose metabolism. Here we show that PGC-1alpha regulates triglyceride metabolism through both farnesoid X receptor (FXR)-dependent and -independent pathways. PGC-1alpha increases FXR activity through two pathways: (1) it increases FXR mRNA levels by coactivation of PPARgamma and HNF4alpha to enhance FXR gene transcription; and (2) it interacts with the DNA-binding domain of FXR to enhance the transcription of FXR target genes. Ectopic expression of PGC-1alpha in murine primary hepatocytes reduces triglyceride secretion by a process that is dependent on the presence of FXR. Consistent with these in vitro studies, we demonstrate that fasting induces hepatic expression of PGC-1alpha and FXR and results in decreased plasma triglyceride levels in wild-type but not in FXR-null mice. Our data suggest that PGC-1alpha plays an important physiological role in maintaining energy homeostasis during fasting by decreasing triglyceride production/secretion while it increases fatty acid beta-oxidation to meet energy needs.
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Affiliation(s)
- Yanqiao Zhang
- Department of Biological Chemistry, University of California at Los Angeles, Los Angeles, CA 90095, USA
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de Beer MC, Castellani LW, Cai L, Stromberg AJ, de Beer FC, van der Westhuyzen DR. ApoA-II modulates the association of HDL with class B scavenger receptors SR-BI and CD36. J Lipid Res 2004; 45:706-15. [PMID: 14729860 DOI: 10.1194/jlr.m300417-jlr200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The class B scavenger receptors SR-BI and CD36 exhibit a broad ligand binding specificity. SR-BI is well characterized as a HDL receptor that mediates selective cholesteryl ester uptake from HDL. CD36, a receptor for oxidized LDL, also binds HDL and mediates selective cholesteryl ester uptake, although much less efficiently than SR-BI. Apolipoprotein A-II (apoA-II), the second most abundant HDL protein, is considered to be proatherogenic, but the underlying mechanisms are unclear. We previously showed that apoA-II modulates SR-BI-dependent binding and selective uptake of cholesteryl ester from reconstituted HDL. To investigate the effect of apoA-II in naturally occurring HDL on these processes, we compared HDL without apoA-II (from apoA-II null mice) with HDLs containing differing amounts of apoA-II (from C57BL/6 mice and transgenic mice expressing a mouse apoA-II transgene). The level of apoA-II in HDL was inversely correlated with HDL binding and selective cholesteryl ester uptake by both scavenger receptors, particularly CD36. Interestingly, for HDL lacking apoA-II, the efficiency with which CD36 mediated selective uptake reached a level similar to that of SR-BI. These results demonstrate that apoA-II exerts a marked effect on HDL binding and selective lipid uptake by the class B scavenger receptors and establishes a potentially important relationship between apoA-II and CD36.
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Affiliation(s)
- Maria C de Beer
- Department of Internal Medicine, University of Kentucky Medical Center, Lexington, KY 40536, USA
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Estrada-Smith D, Castellani LW, Wong H, Wen PZ, Chui A, Lusis AJ, Davis RC. Dissection of multigenic obesity traits in congenic mouse strains. Mamm Genome 2004; 15:14-22. [PMID: 14727138 DOI: 10.1007/s00335-003-2294-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2003] [Accepted: 08/27/2003] [Indexed: 10/26/2022]
Abstract
Previous quantitative trait locus mapping (QTL) identified multigenic obesity (MOB) loci on mouse Chromosome (Chr) 2 that influence the interrelated phenotypes of obesity, insulin resistance, and dyslipidemia. To better localize and characterize the MOB locus, three congenic mouse strains were created. Overlapping genomic intervals from the lean CAST/Ei (CAST) strain were introgressed onto an obesity-susceptible C57BL/6 (BL6) background to create proximal (15 Mb-73 Mb), middle (63 Mb-165 Mb), and distal (83 Mb-182 Mb) congenic strains. The congenic strains showed differences in obesity, insulin, and lipid traits consistent with the original QTL analysis for the locus. Importantly, characterization of the MOB congenics localized the effects of genes that underlie obesity-related traits to an introgressed interval (73-83 Mb) unique to the middle MOB congenic. Conversely, significant differences between the lipid and insulin profiles of the middle and distal MOB congenics implicated the presence of at least two genes that underlie these traits. When fed an atherogenic diet, several traits associated with metabolic syndrome were observed in the distal MOB congenic, while alterations in plasma lipoproteins were observed in the middle MOB congenic strain.
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Affiliation(s)
- Daria Estrada-Smith
- Department of Human Genetics, Gonda/Goldschmeid Center for Neuroscience and Human Genetics Research, 695 Charles E Young Dr South, Room 6524, Los Angeles, CA 90095-7088, USA.
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Abstract
Apolipoprotein A-II (apoA-II) is a major protein on high-density lipoprotein (HDL) particles, and in mice, its levels are associated with triglyceride and glucose metabolism. In particular, transgenic mice overexpressing apoA-II exhibit hypertriglyceridemia, increased body fat, and insulin resistance, whereas apoA-II-null mice have decreased triglycerides and increased insulin sensitivity. Given the phenotypic overlap between familial combined hyperlipidemia (FCH) and apoA-II transgenic mice, we investigated the relationship of apoA-II to this disorder. Despite having lower HDL-cholesterol (HDL-C), FCH subjects had higher apoA-II levels compared with unaffected relatives (P<0.00016). Triglyceride and HDL-C levels were significant predictors of apoA-II, demonstrating that apoA-II variation is associated with several FCH-related traits. After adjustment for multiple covariates, there was evidence for the heritability of apoA-II levels (h2=0.15; P<0.02) in this sample. A genome scan for apoA-II levels identified significant evidence (LOD=3.1) for linkage to a locus on chromosome 1q41, coincident with a suggestive linkage for triglycerides (LOD score=1.4). Thus, this locus may have pleiotropic effects on apoA-II and FCH traits. Our results demonstrate that apoA-II is biochemically and genetically associated with FCH and may serve as a useful marker for understanding the mechanism by which FCH develops.
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Affiliation(s)
- Hooman Allayee
- Department of Human Genetics, Gonda Genetics Research Center, of California, Los Angeles, Calif 90095, USA.
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Abstract
BACKGROUND Serum paraoxonase (PON1), an enzyme carried on HDL, inhibits LDL oxidation, and in human population studies, low PON1 activity is associated with atherosclerosis. In addition, PON1 knockout mice are more susceptible to lipoprotein oxidation and atherosclerosis. To evaluate whether PON1 protects against atherosclerosis and lipid oxidation in a dose-dependent manner, we generated and studied human PON1 transgenic mice. METHODS AND RESULTS Human PON1 transgenic mice were produced by using bacterial artificial chromosome genomic clones. The mice had 2- to 4-fold increased plasma PON1 levels, but plasma cholesterol levels were unchanged. Atherosclerotic lesions were significantly reduced in the transgenic mice when both dietary and apoE-null mouse models were used. HDL isolated from the transgenic mice also protected against LDL oxidation more effectively. CONCLUSIONS Our results indicate that PON1 protects against atherosclerosis in a dose-dependent manner and suggest that it may be a potential target for developing therapeutic agents for the treatment of cardiovascular disease.
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Affiliation(s)
- Aaron Tward
- Department of Medicine, University of California, Los Angeles 90095-1679, USA
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Xiang AH, Azen SP, Buchanan TA, Raffel LJ, Tan S, Cheng LSC, Diaz J, Toscano E, Quinonnes M, Liu CR, Liu CH, Castellani LW, Hsueh WA, Rotter JI, Hodis HN. Heritability of subclinical atherosclerosis in Latino families ascertained through a hypertensive parent. Arterioscler Thromb Vasc Biol 2002; 22:843-8. [PMID: 12006400 DOI: 10.1161/01.atv.0000015329.15481.e8] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Although clinical coronary heart disease and many cardiovascular risk factors are well known to aggregate within families, the heritability of carotid artery intima-media thickness (IMT) is less well documented. We report IMT heritability estimates in Mexican American, Salvadoran American, or Guatemalan American (all referred to as Latino) families ascertained through a hypertensive proband. IMT and cardiovascular risk factors (age, sex, blood pressure, body mass index, lipids, fasting glucose, and insulin sensitivity) were measured in 204 adult offspring of 69 hypertensive probands, along with 82 parents (54 probands and 28 spouses). In the offspring, variance component analysis revealed a heritability for IMT of 64% (P< 0.0001) after adjustment for significant cardiovascular risk factors. Genetic factors accounted for 50% of the total variation in IMT, whereas significant cardiovascular risk factors explained 22% (14% were due to age). For offspring and parents combined, adjusted IMT heritability was less, 34% (P=0.0005), with genetic factors accounting for 18% of the total IMT variation, whereas significant cardiovascular risk factors explained 46% (38% were due to age). We conclude that variation in common carotid artery IMT is heritable in Latino families with a hypertensive proband. Heritability is particularly evident in younger family members, suggesting that acquired factors contribute progressively to IMT variability with aging.
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Affiliation(s)
- Anny H Xiang
- Department of Preventive Medicine, University of Southern California Keck School of Medicine, Los Angeles 90033, USA
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Bodnar JS, Chatterjee A, Castellani LW, Ross DA, Ohmen J, Cavalcoli J, Wu C, Dains KM, Catanese J, Chu M, Sheth SS, Charugundla K, Demant P, West DB, de Jong P, Lusis AJ. Positional cloning of the combined hyperlipidemia gene Hyplip1. Nat Genet 2002; 30:110-6. [PMID: 11753387 PMCID: PMC2846781 DOI: 10.1038/ng811] [Citation(s) in RCA: 170] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Familial combined hyperlipidemia (FCHL, MIM-144250) is a common, multifactorial and heterogeneous dyslipidemia predisposing to premature coronary artery disease and characterized by elevated plasma triglycerides, cholesterol, or both. We identified a mutant mouse strain, HcB-19/Dem (HcB-19), that shares features with FCHL, including hypertriglyceridemia, hypercholesterolemia, elevated plasma apolipoprotein B and increased secretion of triglyceride-rich lipoproteins. The hyperlipidemia results from spontaneous mutation at a locus, Hyplip1, on distal mouse chromosome 3 in a region syntenic with a 1q21-q23 FCHL locus identified in Finnish, German, Chinese and US families. We fine-mapped Hyplip1 to roughly 160 kb, constructed a BAC contig and sequenced overlapping BACs to identify 13 candidate genes. We found substantially decreased mRNA expression for thioredoxin interacting protein (Txnip). Sequencing of the critical region revealed a Txnip nonsense mutation in HcB-19 that is absent in its normolipidemic parental strains. Txnip encodes a cytoplasmic protein that binds and inhibits thioredoxin, a major regulator of cellular redox state. The mutant mice have decreased CO2 production but increased ketone body synthesis, suggesting that altered redox status down-regulates the citric-acid cycle, sparing fatty acids for triglyceride and ketone body production. These results reveal a new pathway of potential clinical significance that contributes to plasma lipid metabolism.
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MESH Headings
- Animals
- Animals, Congenic
- Carbon Dioxide/metabolism
- Carrier Proteins/genetics
- Carrier Proteins/metabolism
- Chromosomes, Artificial, Bacterial/genetics
- Chromosomes, Human, Pair 1/genetics
- Citric Acid Cycle/genetics
- Cloning, Molecular
- Codon/genetics
- Codon, Nonsense
- Contig Mapping
- Cosmids/genetics
- Cricetinae
- Crosses, Genetic
- Disease Models, Animal
- Energy Metabolism/genetics
- Exons/genetics
- Fatty Acids/metabolism
- Haplotypes/genetics
- Humans
- Hybrid Cells
- Hyperlipidemia, Familial Combined/genetics
- Hyperlipidemia, Familial Combined/metabolism
- Ketone Bodies/biosynthesis
- Mice
- Mice, Inbred C3H
- Mice, Inbred C57BL
- Molecular Sequence Data
- Oxidation-Reduction
- Thioredoxins/antagonists & inhibitors
- Triglycerides/blood
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Affiliation(s)
- Jackie S Bodnar
- Department of Medicine, University of California, Los Angeles, 47-123 CHS, UCLA School of Medicine, Los Angeles, California 90095, USA
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Miyake JH, Duong-Polk XT, Taylor JM, Du EZ, Castellani LW, Lusis AJ, Davis RA. Transgenic expression of cholesterol-7-alpha-hydroxylase prevents atherosclerosis in C57BL/6J mice. Arterioscler Thromb Vasc Biol 2002; 22:121-6. [PMID: 11788471 DOI: 10.1161/hq0102.102588] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
C57BL/6J mice are susceptible to atherosclerosis when fed a diet consisting of fat, cholesterol, and taurocholate. The susceptibility to diet-induced atherosclerosis is linked to a reduction in plasma high density lipoprotein (HDL). Diet-induced reduction of plasma HDL shows a physiological and a genetic correlation with repression of cholesterol-7-alpha-hydroxylase, the liver-specific enzyme that regulates the conversion of cholesterol into bile acids. To examine the hypothesis that the repression of cholesterol-7-alpha-hydroxylase is responsible for initiating the metabolic alterations leading to the formation of atherosclerosis and gallstones, we determined whether constitutive transgenic expression of cholesterol-7-alpha-hydroxylase in C57BL/6J mice would confer resistance to these 2 common human diseases. When fed the atherogenic diet, nontransgenic littermates, but not cholesterol-7-alpha-hydroxylase transgenic mice, accumulated cholesterol and cholesterol esters in their livers and plasma. Although the atherogenic diet caused a marked decrease in plasma HDL cholesterol in nontransgenic mice, HDL levels in transgenic mice remained relatively unchanged. Moreover, the ability of cholesterol-7-alpha-hydroxylase transgenic mice to maintain cholesterol and lipoprotein homeostasis completely prevented the formation of atherosclerosis and gallstones. These data establish the integral role that cholesterol-7-alpha-hydroxylase has in maintaining hepatic cholesterol homeostasis and, thus, in the susceptibility to the formation of gallstones and atherosclerosis.
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Affiliation(s)
- Jon H Miyake
- Mammalian Cell and Molecular Biology Laboratory, San Diego State University, San Diego, CA, USA
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46
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Castellani LW, Lusis AJ. ApoA-II versus ApoA-I: two for one is not always a good deal. Arterioscler Thromb Vasc Biol 2001; 21:1870-2. [PMID: 11742857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
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Affiliation(s)
- Lawrence W. Castellani
- Departments of Medicine (L.W.C., A.J.L.) and Microbiology (A.J.L.), Immunology and Molecular Genetics, and Molecular Biology Institute (A.J.L.), University of California, Los Angeles
| | - Aldons J. Lusis
- Departments of Medicine (L.W.C., A.J.L.) and Microbiology (A.J.L.), Immunology and Molecular Genetics, and Molecular Biology Institute (A.J.L.), University of California, Los Angeles
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Miyake JH, Doung XDT, Strauss W, Moore GL, Castellani LW, Curtiss LK, Taylor JM, Davis RA. Increased production of apolipoprotein B-containing lipoproteins in the absence of hyperlipidemia in transgenic mice expressing cholesterol 7α-hydroxylase. J Biol Chem 2001. [DOI: 10.1016/s0021-9258(20)78018-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Miyake JH, Doung XD, Strauss W, Moore GL, Castellani LW, Curtiss LK, Taylor JM, Davis RA. Increased production of apolipoprotein B-containing lipoproteins in the absence of hyperlipidemia in transgenic mice expressing cholesterol 7alpha-hydroxylase. J Biol Chem 2001; 276:23304-11. [PMID: 11323427 DOI: 10.1074/jbc.m101853200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The finding that expression of a cholesterol 7alpha-hydroxylase (CYP7A1) transgene in cultured rat hepatoma cells caused a coordinate increase in lipogenesis and secretion of apoB-containing lipoproteins led to the hypothesis that hepatic production of apoB-containing lipoproteins may be linked to the expression of CYP7A1 (Wang, S.-L., Du, E., Martin, T. D., and Davis, R. A. (1997) J. Biol. Chem. 272, 19351-19358). To examine this hypothesis in vivo, a transgene encoding CYP7A1 driven by the constitutive liver-specific enhancer of the human apoE gene was expressed in C56BL/6 mice. The expression of CYP7A1 mRNA (20-fold), protein ( approximately 10-fold), and enzyme activity (5-fold) was markedly increased in transgenic mice compared with non-transgenic littermates. The bile acid pool of CYP7A1 transgenic mice was doubled mainly due to increased hydrophobic dihydroxy bile acids. In CYP7A1 transgenic mice, livers contained approximately 3-fold more sterol response element-binding protein-2 mRNA. Hepatic expression of mRNAs encoding lipogenic enzymes (i.e. fatty-acid synthase, acetyl-CoA carboxylase, stearoyl-CoA desaturase, squalene synthase, farnesyl-pyrophosphate synthase, 3-hydroxy-3-methylglutaryl-CoA reductase, and low density lipoprotein receptor) as well as microsomal triglyceride transfer protein were elevated approximately 3-5-fold in transgenic mice. CYP7A1 transgenic mice also displayed a >2-fold increase in hepatic production and secretion of triglyceride-rich apoB-containing lipoproteins. Despite the increased hepatic secretion of apoB-containing lipoproteins in CYP7A1 mice, plasma levels of triglycerides and cholesterol were not significantly increased. These data suggest that the 5-fold increased expression of the low density lipoprotein receptor displayed by the livers of CYP7A1 transgenic mice was sufficient to compensate for the 2-fold increase production of apoB-containing lipoproteins. These findings emphasize the important homeostatic role that CYP7A1 plays in balancing the anabolic lipoprotein assembly/secretion pathway with the cholesterol catabolic bile acid synthetic pathway.
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Affiliation(s)
- J H Miyake
- Mammalian Cell and Molecular Biology Laboratory, San Diego State University, San Diego, California 92182-4614, USA
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Hedrick CC, Castellani LW, Wong H, Lusis AJ. In vivo interactions of apoA-II, apoA-I, and hepatic lipase contributing to HDL structure and antiatherogenic functions. J Lipid Res 2001; 42:563-70. [PMID: 11290828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023] Open
Abstract
Studies with mice have revealed that increased expression of apolipoprotein A-II (apoA-II) results in elevations in high density lipoprotein (HDL), the formation of larger HDL, and the development of early atherosclerosis. We now show that the increased size of HDL results in part from an inhibition of the ability of hepatic lipase (HL) to hydrolyze phospholipids and triglycerides in the HDL and that the ratio of apoA-I to apoA-II determines HDL functional and antiatherogenic properties. HDL from apoA-II transgenic mice was relatively resistant to the action of HL in vitro. To test whether HL and apoA-II influence HDL size independently, combined apoA-II transgenic/HL knockout (HLko) mice were examined. These mice had HDL similar in size to apoA-II transgenic mice and HLko mice, suggesting that they do not increase HDL side by independent mechanisms. Overexpression of apoA-I from a transgene reversed many of the effects of apoA-II overexpression, including the ability of HDL to serve as a substrate for HL. Combined apoA-I/apoA-II transgenic mice exhibited significantly less atherosclerotic lesion formation than did apoA-II transgenic mice. These results were paralleled by the effects of the transgenes on the ability of HDL to protect against the proinflammatory effects of oxidized low density lipoprotein (LDL). Whereas nontransgenic HDL protected against oxidized LDL induction of adhesion molecules in endothelial cells, HDL from apoA-II transgenic mice was proinflammatory. HDL from combined apoA-I/apoA-II transgenic mice was equally as protective as HDL from nontransgenic mice. Our data suggest that as the ratio of apoA-II to apoA-I is increased, the HDL become larger because of inhibition of HL, and lose their antiatherogenic properties.
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Affiliation(s)
- C C Hedrick
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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