1
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Zhang S, Williams KJ, Verlande-Ferrero A, Chan AP, Su GB, Kershaw EE, Cox JE, Maschek JA, Shapira SN, Christofk HR, de Aguiar Vallim TQ, Masri S, Villanueva CJ. Acute activation of adipocyte lipolysis reveals dynamic lipid remodeling of the hepatic lipidome. J Lipid Res 2024; 65:100434. [PMID: 37640283 PMCID: PMC10839691 DOI: 10.1016/j.jlr.2023.100434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 06/07/2023] [Revised: 07/27/2023] [Accepted: 08/16/2023] [Indexed: 08/31/2023] Open
Abstract
Adipose tissue is the site of long-term energy storage. During the fasting state, exercise, and cold exposure, the white adipose tissue mobilizes energy for peripheral tissues through lipolysis. The mobilization of lipids from white adipose tissue to the liver can lead to excess triglyceride accumulation and fatty liver disease. Although the white adipose tissue is known to release free fatty acids, a comprehensive analysis of lipids mobilized from white adipocytes in vivo has not been completed. In these studies, we provide a comprehensive quantitative analysis of the adipocyte-secreted lipidome and show that there is interorgan crosstalk with liver. Our analysis identifies multiple lipid classes released by adipocytes in response to activation of lipolysis. Time-dependent analysis of the serum lipidome showed that free fatty acids increase within 30 min of β3-adrenergic receptor activation and subsequently decrease, followed by a rise in serum triglycerides, liver triglycerides, and several ceramide species. The triglyceride composition of liver is enriched for linoleic acid despite higher concentrations of palmitate in the blood. To further validate that these findings were a specific consequence of lipolysis, we generated mice with conditional deletion of adipose tissue triglyceride lipase exclusively in adipocytes. This loss of in vivo adipocyte lipolysis prevented the rise in serum free fatty acids and hepatic triglycerides. Furthermore, conditioned media from adipocytes promotes lipid remodeling in hepatocytes with concomitant changes in genes/pathways mediating lipid utilization. Together, these data highlight critical role of adipocyte lipolysis in interorgan crosstalk between adipocytes and liver.
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Affiliation(s)
- Sicheng Zhang
- Department of Integrative Biology and Physiology, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Kevin J Williams
- UCLA Lipidomics Lab, Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Amandine Verlande-Ferrero
- Department of Biological Chemistry, Center for Epigenetics and Metabolism, Chao Family Comprehensive Cancer Center, University of California, Irvine (UCI), Irvine, CA, USA
| | - Alvin P Chan
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Gino B Su
- UCLA Lipidomics Lab, Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Erin E Kershaw
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, PA, USA
| | - James E Cox
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - John Alan Maschek
- Nutrition and Integrative Physiology, College of Health, University of Utah, Salt Lake City, UT, USA
| | - Suzanne N Shapira
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Heather R Christofk
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA; Molecular Biology Institute, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Thomas Q de Aguiar Vallim
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA; Molecular Biology Institute, University of California, Los Angeles (UCLA), Los Angeles, CA, USA; Division of Cardiology, Department of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Selma Masri
- Department of Biological Chemistry, Center for Epigenetics and Metabolism, Chao Family Comprehensive Cancer Center, University of California, Irvine (UCI), Irvine, CA, USA
| | - Claudio J Villanueva
- Department of Integrative Biology and Physiology, University of California, Los Angeles (UCLA), Los Angeles, CA, USA; Molecular Biology Institute, University of California, Los Angeles (UCLA), Los Angeles, CA, USA.
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2
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Zhang Z, Cui Y, Su V, Wang D, Tol MJ, Cheng L, Wu X, Kim J, Rajbhandari P, Zhang S, Li W, Tontonoz P, Villanueva CJ, Sallam T. A PPARγ/long noncoding RNA axis regulates adipose thermoneutral remodeling in mice. J Clin Invest 2023; 133:e170072. [PMID: 37909330 PMCID: PMC10617768 DOI: 10.1172/jci170072] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [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: 03/06/2023] [Accepted: 09/06/2023] [Indexed: 11/03/2023] Open
Abstract
Interplay between energy-storing white adipose cells and thermogenic beige adipocytes contributes to obesity and insulin resistance. Irrespective of specialized niche, adipocytes require the activity of the nuclear receptor PPARγ for proper function. Exposure to cold or adrenergic signaling enriches thermogenic cells though multiple pathways that act synergistically with PPARγ; however, the molecular mechanisms by which PPARγ licenses white adipose tissue to preferentially adopt a thermogenic or white adipose fate in response to dietary cues or thermoneutral conditions are not fully elucidated. Here, we show that a PPARγ/long noncoding RNA (lncRNA) axis integrates canonical and noncanonical thermogenesis to restrain white adipose tissue heat dissipation during thermoneutrality and diet-induced obesity. Pharmacologic inhibition or genetic deletion of the lncRNA Lexis enhances uncoupling protein 1-dependent (UCP1-dependent) and -independent thermogenesis. Adipose-specific deletion of Lexis counteracted diet-induced obesity, improved insulin sensitivity, and enhanced energy expenditure. Single-nuclei transcriptomics revealed that Lexis regulates a distinct population of thermogenic adipocytes. We systematically map Lexis motif preferences and show that it regulates the thermogenic program through the activity of the metabolic GWAS gene and WNT modulator TCF7L2. Collectively, our studies uncover a new mode of crosstalk between PPARγ and WNT that preserves white adipose tissue plasticity.
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Affiliation(s)
- Zhengyi Zhang
- Division of Cardiology, Department of Medicine
- Department of Physiology, and
- Molecular Biology Institute, UCLA, Los Angeles, California, USA
| | - Ya Cui
- Division of Computational Biomedicine, Biological Chemistry, University of California, Irvine, Irvine, California, USA
| | - Vivien Su
- Division of Cardiology, Department of Medicine
- Department of Physiology, and
- Molecular Biology Institute, UCLA, Los Angeles, California, USA
| | - Dan Wang
- Division of Cardiology, Department of Medicine
- Department of Physiology, and
- Molecular Biology Institute, UCLA, Los Angeles, California, USA
| | - Marcus J. Tol
- Molecular Biology Institute, UCLA, Los Angeles, California, USA
- Department of Pathology and Laboratory Medicine, UCLA, Los Angeles, California, USA
| | - Lijing Cheng
- Division of Cardiology, Department of Medicine
- Department of Physiology, and
- Molecular Biology Institute, UCLA, Los Angeles, California, USA
| | - Xiaohui Wu
- Division of Cardiology, Department of Medicine
- Department of Physiology, and
- Molecular Biology Institute, UCLA, Los Angeles, California, USA
| | - Jason Kim
- Division of Cardiology, Department of Medicine
- Department of Physiology, and
- Molecular Biology Institute, UCLA, Los Angeles, California, USA
| | - Prashant Rajbhandari
- Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Sicheng Zhang
- Molecular Biology Institute, UCLA, Los Angeles, California, USA
| | - Wei Li
- Division of Computational Biomedicine, Biological Chemistry, University of California, Irvine, Irvine, California, USA
| | - Peter Tontonoz
- Molecular Biology Institute, UCLA, Los Angeles, California, USA
- Department of Pathology and Laboratory Medicine, UCLA, Los Angeles, California, USA
- Department of Biological Chemistry and
| | - Claudio J. Villanueva
- Molecular Biology Institute, UCLA, Los Angeles, California, USA
- Department of Integrative Biology and Physiology, College of Life Sciences, UCLA, Los Angeles, California, USA
| | - Tamer Sallam
- Division of Cardiology, Department of Medicine
- Department of Physiology, and
- Molecular Biology Institute, UCLA, Los Angeles, California, USA
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3
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Johnson JM, Peterlin AD, Balderas E, Sustarsic EG, Maschek JA, Lang MJ, Jara-Ramos A, Panic V, Morgan JT, Villanueva CJ, Sanchez A, Rutter J, Lodhi IJ, Cox JE, Fisher-Wellman KH, Chaudhuri D, Gerhart-Hines Z, Funai K. Mitochondrial phosphatidylethanolamine modulates UCP1 to promote brown adipose thermogenesis. Sci Adv 2023; 9:eade7864. [PMID: 36827367 PMCID: PMC9956115 DOI: 10.1126/sciadv.ade7864] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 01/24/2023] [Indexed: 05/08/2023]
Abstract
Thermogenesis by uncoupling protein 1 (UCP1) is one of the primary mechanisms by which brown adipose tissue (BAT) increases energy expenditure. UCP1 resides in the inner mitochondrial membrane (IMM), where it dissipates membrane potential independent of adenosine triphosphate (ATP) synthase. Here, we provide evidence that phosphatidylethanolamine (PE) modulates UCP1-dependent proton conductance across the IMM to modulate thermogenesis. Mitochondrial lipidomic analyses revealed PE as a signature molecule whose abundance bidirectionally responds to changes in thermogenic burden. Reduction in mitochondrial PE by deletion of phosphatidylserine decarboxylase (PSD) made mice cold intolerant and insensitive to β3 adrenergic receptor agonist-induced increase in whole-body oxygen consumption. High-resolution respirometry and fluorometry of BAT mitochondria showed that loss of mitochondrial PE specifically lowers UCP1-dependent respiration without compromising electron transfer efficiency or ATP synthesis. These findings were confirmed by a reduction in UCP1 proton current in PE-deficient mitoplasts. Thus, PE performs a previously unknown role as a temperature-responsive rheostat that regulates UCP1-dependent thermogenesis.
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Affiliation(s)
- Jordan M. Johnson
- Diabetes and Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Alek D. Peterlin
- Diabetes and Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
- Utah Center for Clinical and Translational Research, University of Utah, Salt Lake City, UT, USA
| | - Enrique Balderas
- Nora Eccles Harrison Cardiovascular Research and Training Institute, Division of Cardiovascular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Elahu G. Sustarsic
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - J. Alan Maschek
- Diabetes and Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
- Metabolomics Core Research Facility, University of Utah, Salt Lake City, UT, USA
| | - Marisa J. Lang
- Diabetes and Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Alejandro Jara-Ramos
- Nora Eccles Harrison Cardiovascular Research and Training Institute, Division of Cardiovascular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Vanja Panic
- Diabetes and Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Jeffrey T. Morgan
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
- Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA
| | - Claudio J. Villanueva
- Diabetes and Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
- Department of Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, CA, USA
| | - Alejandro Sanchez
- Division of Urology, Department of Surgery, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, USA
| | - Jared Rutter
- Diabetes and Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
- Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA
| | - Irfan J. Lodhi
- Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, St. Louis, MO, USA
| | - James E. Cox
- Diabetes and Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Metabolomics Core Research Facility, University of Utah, Salt Lake City, UT, USA
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | | | - Dipayan Chaudhuri
- Nora Eccles Harrison Cardiovascular Research and Training Institute, Division of Cardiovascular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Zachary Gerhart-Hines
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Katsuhiko Funai
- Diabetes and Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA
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4
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Xiao X, Kennelly JP, Ferrari A, Clifford BL, Whang E, Gao Y, Qian K, Sandhu J, Jarrett KE, Brearley-Sholto MC, Nguyen A, Nagari RT, Lee MS, Zhang S, Weston TA, Young SG, Bensinger SJ, Villanueva CJ, de Aguiar Vallim TQ, Tontonoz P. Hepatic nonvesicular cholesterol transport is critical for systemic lipid homeostasis. Nat Metab 2023; 5:165-181. [PMID: 36646756 PMCID: PMC9995220 DOI: 10.1038/s42255-022-00722-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [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: 05/02/2022] [Accepted: 11/10/2022] [Indexed: 01/18/2023]
Abstract
In cell models, changes in the 'accessible' pool of plasma membrane (PM) cholesterol are linked with the regulation of endoplasmic reticulum sterol synthesis and metabolism by the Aster family of nonvesicular transporters; however, the relevance of such nonvesicular transport mechanisms for lipid homeostasis in vivo has not been defined. Here we reveal two physiological contexts that generate accessible PM cholesterol and engage the Aster pathway in the liver: fasting and reverse cholesterol transport. During fasting, adipose-tissue-derived fatty acids activate hepatocyte sphingomyelinase to liberate sequestered PM cholesterol. Aster-dependent cholesterol transport during fasting facilitates cholesteryl ester formation, cholesterol movement into bile and very low-density lipoprotein production. During reverse cholesterol transport, high-density lipoprotein delivers excess cholesterol to the hepatocyte PM through scavenger receptor class B member 1. Loss of hepatic Asters impairs cholesterol movement into feces, raises plasma cholesterol levels and causes cholesterol accumulation in peripheral tissues. These results reveal fundamental mechanisms by which Aster cholesterol flux contributes to hepatic and systemic lipid homeostasis.
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Affiliation(s)
- Xu Xiao
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, CA, USA
| | - John Paul Kennelly
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, CA, USA
| | - Alessandra Ferrari
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, CA, USA
| | - Bethan L Clifford
- Department of Medicine, Division of Cardiology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Emily Whang
- Pediatric Gastroenterology, Hepatology and Nutrition, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Yajing Gao
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, CA, USA
| | - Kevin Qian
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, CA, USA
| | - Jaspreet Sandhu
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA, USA
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA, USA
| | - Kelsey E Jarrett
- Department of Medicine, Division of Cardiology, University of California, Los Angeles, Los Angeles, CA, USA
| | | | - Alexander Nguyen
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA, USA
- Vatche and Tamar Manoukian Division of Digestive Diseases, Department of Medicine David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Rohith T Nagari
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, CA, USA
| | - Min Sub Lee
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Sicheng Zhang
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Thomas A Weston
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Stephen G Young
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Human Genetics, University of California, Los Angeles, Los Angeles, CA, USA
| | - Steven J Bensinger
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA, USA
| | - Claudio J Villanueva
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Thomas Q de Aguiar Vallim
- Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Medicine, Division of Cardiology, University of California, Los Angeles, Los Angeles, CA, USA
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA, USA
- Jonsson Comprehensive Cancer Center (JCCC), University of California, Los Angeles, Los Angeles, CA, USA
| | - Peter Tontonoz
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA, USA.
- Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, CA, USA.
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5
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Sakers A, De Siqueira MK, Seale P, Villanueva CJ. Adipose-tissue plasticity in health and disease. Cell 2022; 185:419-446. [PMID: 35120662 DOI: 10.1016/j.cell.2021.12.016] [Citation(s) in RCA: 217] [Impact Index Per Article: 108.5] [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: 09/20/2021] [Revised: 12/08/2021] [Accepted: 12/13/2021] [Indexed: 12/11/2022]
Abstract
Adipose tissue, colloquially known as "fat," is an extraordinarily flexible and heterogeneous organ. While historically viewed as a passive site for energy storage, we now appreciate that adipose tissue regulates many aspects of whole-body physiology, including food intake, maintenance of energy levels, insulin sensitivity, body temperature, and immune responses. A crucial property of adipose tissue is its high degree of plasticity. Physiologic stimuli induce dramatic alterations in adipose-tissue metabolism, structure, and phenotype to meet the needs of the organism. Limitations to this plasticity cause diminished or aberrant responses to physiologic cues and drive the progression of cardiometabolic disease along with other pathological consequences of obesity.
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Affiliation(s)
- Alexander Sakers
- Institute for Diabetes, Obesity & Metabolism, Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104 USA
| | - Mirian Krystel De Siqueira
- Molecular, Cellular & Integrative Physiology Program, University of California, Los Angeles, Los Angeles, CA 90095-7070 USA; Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA 90095-7070 USA
| | - Patrick Seale
- Institute for Diabetes, Obesity & Metabolism, Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104 USA.
| | - Claudio J Villanueva
- Molecular, Cellular & Integrative Physiology Program, University of California, Los Angeles, Los Angeles, CA 90095-7070 USA; Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA 90095-7070 USA.
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6
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De Siqueira MK, Villanueva CJ. When fat talks, the gut listens: IRONing out metabolism. Cell Metab 2021; 33:1505-1506. [PMID: 34348093 DOI: 10.1016/j.cmet.2021.07.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 11/27/2022]
Abstract
In a new study, Zhang et al. (2021) show that reducing iron levels in adipose tissue improves metabolic function. This occurs through an interorgan communication system where signals from the adipocyte reduce intestinal lipid absorption.
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Affiliation(s)
- Mirian Krystel De Siqueira
- Department of Integrative Biology and Physiology, Molecular Cellular Integrative Physiology Program, Molecular Biology Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Claudio J Villanueva
- Department of Integrative Biology and Physiology, Molecular Cellular Integrative Physiology Program, Molecular Biology Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.
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7
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Panic V, Pearson S, Banks J, Tippetts TS, Velasco-Silva JN, Lee S, Simcox J, Geoghegan G, Bensard CL, van Ry T, Holland WL, Summers SA, Cox J, Ducker GS, Rutter J, Villanueva CJ. Mitochondrial pyruvate carrier is required for optimal brown fat thermogenesis. eLife 2020; 9:52558. [PMID: 32795388 PMCID: PMC7476754 DOI: 10.7554/elife.52558] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 08/13/2020] [Indexed: 12/14/2022] Open
Abstract
Brown adipose tissue (BAT) is composed of thermogenic cells that convert chemical energy into heat to maintain a constant body temperature and counteract metabolic disease. The metabolic adaptations required for thermogenesis are not fully understood. Here, we explore how steady state levels of metabolic intermediates are altered in brown adipose tissue in response to cold exposure. Transcriptome and metabolome analysis revealed changes in pathways involved in amino acid, glucose, and TCA cycle metabolism. Using isotopic labeling experiments, we found that activated brown adipocytes increased labeling of pyruvate and TCA cycle intermediates from U13C-glucose. Although glucose oxidation has been implicated as being essential for thermogenesis, its requirement for efficient thermogenesis has not been directly tested. We show that mitochondrial pyruvate uptake is essential for optimal thermogenesis, as conditional deletion of Mpc1 in brown adipocytes leads to impaired cold adaptation. Isotopic labeling experiments using U13C-glucose showed that loss of MPC1 led to impaired labeling of TCA cycle intermediates. Loss of MPC1 in BAT increased 3-hydroxybutyrate levels in blood and BAT in response to the cold, suggesting that ketogenesis provides an alternative fuel source to compensate. Collectively, these studies highlight that complete glucose oxidation is essential for optimal brown fat thermogenesis.
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Affiliation(s)
- Vanja Panic
- Department of Biochemistry, University of Utah, Salt Lake City, United States
| | - Stephanie Pearson
- Department of Biochemistry, University of Utah, Salt Lake City, United States
| | - James Banks
- Department of Biochemistry, University of Utah, Salt Lake City, United States
| | - Trevor S Tippetts
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, United States
| | | | - Sanghoon Lee
- Department of Biochemistry, University of Utah, Salt Lake City, United States
| | - Judith Simcox
- Department of Biochemistry, University of Utah, Salt Lake City, United States
| | - Gisela Geoghegan
- Department of Biochemistry, University of Utah, Salt Lake City, United States
| | - Claire L Bensard
- Department of Biochemistry, University of Utah, Salt Lake City, United States
| | - Tyler van Ry
- Department of Biochemistry, University of Utah, Salt Lake City, United States
| | - Will L Holland
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, United States
| | - Scott A Summers
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, United States
| | - James Cox
- Department of Biochemistry, University of Utah, Salt Lake City, United States
| | - Gregory S Ducker
- Department of Biochemistry, University of Utah, Salt Lake City, United States
| | - Jared Rutter
- Department of Biochemistry, University of Utah, Salt Lake City, United States.,Howard Hughes Medical Institute, University of Utah, Salt Lake City, United States
| | - Claudio J Villanueva
- Department of Biochemistry, University of Utah, Salt Lake City, United States.,Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, United States
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8
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9
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Petersen C, Bell R, Klag KA, Lee SH, Soto R, Ghazaryan A, Buhrke K, Ekiz HA, Ost KS, Boudina S, O'Connell RM, Cox JE, Villanueva CJ, Stephens WZ, Round JL. T cell-mediated regulation of the microbiota protects against obesity. Science 2020; 365:365/6451/eaat9351. [PMID: 31346040 DOI: 10.1126/science.aat9351] [Citation(s) in RCA: 208] [Impact Index Per Article: 52.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 02/22/2019] [Accepted: 06/13/2019] [Indexed: 12/16/2022]
Abstract
The microbiota influences obesity, yet organisms that protect from disease remain unknown. During studies interrogating host-microbiota interactions, we observed the development of age-associated metabolic syndrome (MetS). Expansion of Desulfovibrio and loss of Clostridia were key features associated with obesity in this model and are present in humans with MetS. T cell-dependent events were required to prevent disease, and replacement of Clostridia rescued obesity. Inappropriate immunoglobulin A targeting of Clostridia and increased Desulfovibrio antagonized the colonization of beneficial Clostridia. Transcriptional and metabolic analysis revealed enhanced lipid absorption in the obese host. Colonization of germ-free mice with Clostridia, but not Desulfovibrio, down-regulated genes that control lipid absorption and reduced adiposity. Thus, immune control of the microbiota maintains beneficial microbial populations that constrain lipid metabolism to prevent MetS.
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Affiliation(s)
- Charisse Petersen
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Rickesha Bell
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Kendra A Klag
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Soh-Hyun Lee
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Raymond Soto
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Arevik Ghazaryan
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Kaitlin Buhrke
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - H Atakan Ekiz
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Kyla S Ost
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Sihem Boudina
- Department of Nutrition and Integrative Physiology, College of Health, University of Utah, Salt Lake City, UT 84112, USA
| | - Ryan M O'Connell
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - James E Cox
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Claudio J Villanueva
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - W Zac Stephens
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
| | - June L Round
- Department of Pathology, Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
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10
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Verkerke ARP, Ferrara PJ, Lin CT, Johnson JM, Ryan TE, Maschek JA, Eshima H, Paran CW, Laing BT, Siripoksup P, Tippetts TS, Wentzler EJ, Huang H, Spangenburg EE, Brault JJ, Villanueva CJ, Summers SA, Holland WL, Cox JE, Vance DE, Neufer PD, Funai K. Phospholipid methylation regulates muscle metabolic rate through Ca 2+ transport efficiency. Nat Metab 2019; 1:876-885. [PMID: 32405618 PMCID: PMC7218817 DOI: 10.1038/s42255-019-0111-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [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: 12/13/2022]
Abstract
The biophysical environment of membrane phospholipids affects structure, function, and stability of membrane-bound proteins.1,2 Obesity can disrupt membrane lipids, and in particular, alter the activity of sarco/endoplasmic reticulum (ER/SR) Ca2+-ATPase (SERCA) to affect cellular metabolism.3-5 Recent evidence suggests that transport efficiency (Ca2+ uptake / ATP hydrolysis) of skeletal muscle SERCA can be uncoupled to increase energy expenditure and protect mice from diet-induced obesity.6,7 In isolated SR vesicles, membrane phospholipid composition is known to modulate SERCA efficiency.8-11 Here we show that skeletal muscle SR phospholipids can be altered to decrease SERCA efficiency and increase whole-body metabolic rate. The absence of skeletal muscle phosphatidylethanolamine (PE) methyltransferase (PEMT) promotes an increase in skeletal muscle and whole-body metabolic rate to protect mice from diet-induced obesity. The elevation in metabolic rate is caused by a decrease in SERCA Ca2+-transport efficiency, whereas mitochondrial uncoupling is unaffected. Our findings support the hypothesis that skeletal muscle energy efficiency can be reduced to promote protection from obesity.
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Affiliation(s)
- Anthony R P Verkerke
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition & Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Patrick J Ferrara
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition & Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Chien-Te Lin
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Jordan M Johnson
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition & Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Terence E Ryan
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA
| | - J Alan Maschek
- Metabolomics Core Research Facility, University of Utah, Salt Lake City, UT, USA
| | - Hiroaki Eshima
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
| | - Christopher W Paran
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Brenton T Laing
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Piyarat Siripoksup
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Physical Therapy & Athletic Training, University of Utah, Salt Lake City, UT, USA
| | - Trevor S Tippetts
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition & Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Edward J Wentzler
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Hu Huang
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Espen E Spangenburg
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Jeffrey J Brault
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Claudio J Villanueva
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Scott A Summers
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition & Integrative Physiology, University of Utah, Salt Lake City, UT, USA
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA
| | - William L Holland
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition & Integrative Physiology, University of Utah, Salt Lake City, UT, USA
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA
| | - James E Cox
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Metabolomics Core Research Facility, University of Utah, Salt Lake City, UT, USA
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Dennis E Vance
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - P Darrell Neufer
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Katsuhiko Funai
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA.
- Department of Nutrition & Integrative Physiology, University of Utah, Salt Lake City, UT, USA.
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA.
- Department of Physical Therapy & Athletic Training, University of Utah, Salt Lake City, UT, USA.
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA.
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11
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Geoghegan G, Simcox J, Seldin MM, Parnell TJ, Stubben C, Just S, Begaye L, Lusis AJ, Villanueva CJ. Targeted deletion of Tcf7l2 in adipocytes promotes adipocyte hypertrophy and impaired glucose metabolism. Mol Metab 2019; 24:44-63. [PMID: 30948248 PMCID: PMC6531814 DOI: 10.1016/j.molmet.2019.03.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 03/02/2019] [Accepted: 03/09/2019] [Indexed: 12/15/2022] Open
Abstract
OBJECTIVE Activation of the Wnt-signaling pathway is known to inhibit differentiation in adipocytes. However, there is a gap in our understanding of the transcriptional network regulated by components of the Wnt-signaling pathway during adipogenesis and in adipocytes during postnatal life. The key intracellular effectors of the Wnt-signaling pathway occur through TCF transcription factors such as TCF7L2 (transcription factor-7-like 2). Several genetic variants in proximity to TCF7L2 have been linked to type 2 diabetes through genome-wide association studies in various human populations. Our work aims to functionally characterize the adipocyte specific gene program regulated by TCF7L2 and understand how this program regulates metabolism. METHODS We generated Tcf7l2F/F mice and assessed TCF7L2 function in isolated adipocytes and adipose specific knockout mice. ChIP-sequencing and RNA-sequencing was performed on the isolated adipocytes with control and TCF7L2 knockout cells. Adipose specific TCF7L2 knockout mice were challenged with high fat diet and assessed for body weight, glucose tolerance, and lipolysis. RESULTS Here we report that TCF7L2 regulates adipocyte size, endocrine function, and glucose metabolism. Tcf7l2 is highly expressed in white adipose tissue, and its expression is suppressed in genetic and diet-induced models of obesity. Genome-wide distribution of TCF7L2 binding and gene expression analysis in adipocytes suggests that TCF7L2 directly regulates genes implicated in cellular metabolism and cell cycle control. When challenged with a high-fat diet, conditional deletion of TCF7L2 in adipocytes led to impaired glucose tolerance, impaired insulin sensitivity, promoted weight gain, and increased adipose tissue mass. This was accompanied by reduced expression of triglyceride hydrolase, reduced fasting-induced free fatty acid release, and adipocyte hypertrophy in subcutaneous adipose tissue. CONCLUSIONS Together our studies support that TCF7L2 is a central transcriptional regulator of the adipocyte metabolic program by directly regulating the expression of genes involved in lipid and glucose metabolism.
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Affiliation(s)
- Gisela Geoghegan
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Judith Simcox
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Marcus M Seldin
- Department of Human Genetics/Medicine, University of California, Los Angeles, CA, USA; Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA, USA
| | - Timothy J Parnell
- Bioinformatics Shared Resources, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, USA
| | - Chris Stubben
- Bioinformatics Shared Resources, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, USA
| | - Steven Just
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Lori Begaye
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Aldons J Lusis
- Department of Human Genetics/Medicine, University of California, Los Angeles, CA, USA; Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA, USA
| | - Claudio J Villanueva
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA.
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12
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Runtsch MC, Nelson MC, Lee SH, Voth W, Alexander M, Hu R, Wallace J, Petersen C, Panic V, Villanueva CJ, Evason KJ, Bauer KM, Mosbruger T, Boudina S, Bronner M, Round JL, Drummond MJ, O’Connell RM. Anti-inflammatory microRNA-146a protects mice from diet-induced metabolic disease. PLoS Genet 2019; 15:e1007970. [PMID: 30768595 PMCID: PMC6395003 DOI: 10.1371/journal.pgen.1007970] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [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: 07/10/2018] [Revised: 02/28/2019] [Accepted: 01/16/2019] [Indexed: 12/15/2022] Open
Abstract
Identifying regulatory mechanisms that influence inflammation in metabolic tissues is critical for developing novel metabolic disease treatments. Here, we investigated the role of microRNA-146a (miR-146a) during diet-induced obesity in mice. miR-146a is reduced in obese and type 2 diabetic patients and our results reveal that miR-146a-/- mice fed a high-fat diet (HFD) have exaggerated weight gain, increased adiposity, hepatosteatosis, and dysregulated blood glucose levels compared to wild-type controls. Pro-inflammatory genes and NF-κB activation increase in miR-146a-/- mice, indicating a role for this miRNA in regulating inflammatory pathways. RNA-sequencing of adipose tissue macrophages demonstrated a role for miR-146a in regulating both inflammation and cellular metabolism, including the mTOR pathway, during obesity. Further, we demonstrate that miR-146a regulates inflammation, cellular respiration and glycolysis in macrophages through a mechanism involving its direct target Traf6. Finally, we found that administration of rapamycin, an inhibitor of mTOR, was able to rescue the obesity phenotype in miR-146a-/- mice. Altogether, our study provides evidence that miR-146a represses inflammation and diet-induced obesity and regulates metabolic processes at the cellular and organismal levels, demonstrating how the combination of diet and miRNA genetics influences obesity and diabetic phenotypes.
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Affiliation(s)
- Marah C. Runtsch
- Department of Pathology, University of Utah, Salt Lake City, Utah, United States of America
| | - Morgan C. Nelson
- Department of Pathology, University of Utah, Salt Lake City, Utah, United States of America
| | - Soh-Hyun Lee
- Department of Pathology, University of Utah, Salt Lake City, Utah, United States of America
| | - Warren Voth
- Department of Pathology, University of Utah, Salt Lake City, Utah, United States of America
| | - Margaret Alexander
- Department of Pathology, University of Utah, Salt Lake City, Utah, United States of America
| | - Ruozhen Hu
- Department of Pathology, University of Utah, Salt Lake City, Utah, United States of America
| | - Jared Wallace
- Department of Pathology, University of Utah, Salt Lake City, Utah, United States of America
| | - Charisse Petersen
- Department of Pathology, University of Utah, Salt Lake City, Utah, United States of America
| | - Vanja Panic
- Department of Biochemistry, University of Utah, Salt Lake City, Utah, United States of America
| | - Claudio J. Villanueva
- Department of Biochemistry, University of Utah, Salt Lake City, Utah, United States of America
| | - Kimberley J. Evason
- Department of Pathology, University of Utah, Salt Lake City, Utah, United States of America
| | - Kaylyn M. Bauer
- Department of Pathology, University of Utah, Salt Lake City, Utah, United States of America
| | - Timothy Mosbruger
- Bioinformatics, Huntsman Cancer Institute and University of Utah, Salt Lake City, Utah, United States of America
| | - Sihem Boudina
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, United States of America
| | - Mary Bronner
- Department of Pathology, University of Utah, Salt Lake City, Utah, United States of America
| | - June L. Round
- Department of Pathology, University of Utah, Salt Lake City, Utah, United States of America
| | - Micah J. Drummond
- Department of Physical Therapy and Athletic Training, University of Utah, Salt Lake City, Utah, United States of America
| | - Ryan M. O’Connell
- Department of Pathology, University of Utah, Salt Lake City, Utah, United States of America
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13
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Bond ST, Moody SC, Liu Y, Civelek M, Villanueva CJ, Gregorevic P, Kingwell BA, Hevener AL, Lusis AJ, Henstridge DC, Calkin AC, Drew BG. The E3 ligase MARCH5 is a PPARγ target gene that regulates mitochondria and metabolism in adipocytes. Am J Physiol Endocrinol Metab 2019; 316:E293-E304. [PMID: 30512991 PMCID: PMC6397360 DOI: 10.1152/ajpendo.00394.2018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mitochondrial dynamics refers to the constant remodeling of mitochondrial populations by multiple cellular pathways that help maintain mitochondrial health and function. Disruptions in mitochondrial dynamics often lead to mitochondrial dysfunction, which is frequently associated with disease in rodents and humans. Consistent with this, obesity is associated with reduced mitochondrial function in white adipose tissue, partly via alterations in mitochondrial dynamics. Several proteins, including the E3 ubiquitin ligase membrane-associated RING-CH-type finger 5 (MARCH5), are known to regulate mitochondrial dynamics; however, the role of these proteins in adipocytes has been poorly studied. Here, we show that MARCH5 is regulated by peroxisome proliferator-activated receptor-γ (PPARγ) during adipogenesis and is correlated with fat mass across a panel of genetically diverse mouse strains, in ob/ob mice, and in humans. Furthermore, manipulation of MARCH5 expression in vitro and in vivo alters mitochondrial function, affects cellular metabolism, and leads to differential regulation of several metabolic genes. Thus our data demonstrate an association between mitochondrial dynamics and metabolism that defines MARCH5 as a critical link between these interconnected pathways.
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Affiliation(s)
- Simon T Bond
- Baker Heart and Diabetes Institute , Melbourne, Victoria , Australia
| | - Sarah C Moody
- Baker Heart and Diabetes Institute , Melbourne, Victoria , Australia
| | - Yingying Liu
- Baker Heart and Diabetes Institute , Melbourne, Victoria , Australia
| | - Mete Civelek
- University of California , Los Angeles, California
| | | | - Paul Gregorevic
- Baker Heart and Diabetes Institute , Melbourne, Victoria , Australia
| | | | | | | | | | - Anna C Calkin
- Baker Heart and Diabetes Institute , Melbourne, Victoria , Australia
- Central Clinical School, Monash University , Melbourne, Victoria , Australia
| | - Brian G Drew
- Baker Heart and Diabetes Institute , Melbourne, Victoria , Australia
- Central Clinical School, Monash University , Melbourne, Victoria , Australia
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14
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Storelli G, Nam HJ, Simcox J, Villanueva CJ, Thummel CS. Drosophila HNF4 Directs a Switch in Lipid Metabolism that Supports the Transition to Adulthood. Dev Cell 2018; 48:200-214.e6. [PMID: 30554999 DOI: 10.1016/j.devcel.2018.11.030] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [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: 07/09/2018] [Revised: 10/09/2018] [Accepted: 11/14/2018] [Indexed: 12/20/2022]
Abstract
Animals must adjust their metabolism as they progress through development in order to meet the needs of each stage in the life cycle. Here, we show that the dHNF4 nuclear receptor acts at the onset of Drosophila adulthood to direct an essential switch in lipid metabolism. Lipid stores are consumed shortly after metamorphosis but contribute little to energy metabolism. Rather, dHNF4 directs their conversion to very long chain fatty acids and hydrocarbons, which waterproof the animal to preserve fluid homeostasis. Similarly, HNF4α is required in mouse hepatocytes for the expression of fatty acid elongases that contribute to a waterproof epidermis, suggesting that this pathway is conserved through evolution. This developmental switch in Drosophila lipid metabolism promotes lifespan and desiccation resistance in adults and suppresses hallmarks of diabetes, including elevated glucose levels and intolerance to dietary sugars. These studies establish dHNF4 as a regulator of the adult metabolic state.
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Affiliation(s)
- Gilles Storelli
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112-5330, USA.
| | - Hyuck-Jin Nam
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112-5330, USA
| | - Judith Simcox
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Claudio J Villanueva
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Carl S Thummel
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112-5330, USA.
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15
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Chang SH, Yun UJ, Choi JH, Kim S, Lee AR, Lee DH, Seo MJ, Panic V, Villanueva CJ, Song NJ, Park KW. Identification of Phf16 and Pnpla3 as new adipogenic factors regulated by phytochemicals. J Cell Biochem 2018; 120:3599-3610. [PMID: 30272815 DOI: 10.1002/jcb.27637] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [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: 01/04/2018] [Accepted: 08/14/2018] [Indexed: 01/01/2023]
Abstract
Adipocyte differentiation is controlled by multiple signaling pathways. To identify new adipogenic factors, C3H10T1/2 adipocytes were treated with previously known antiadipogenic phytochemicals (resveratrol, butein, sulfuretin, and fisetin) for 24 hours. Commonly regulated genes were then identified by transcriptional profiling analysis. Three genes (chemokine (C-X-C motif) ligand 1 [ Cxcl1], heme oxygenase 1 [ Hmox1], and PHD (plant homeo domain) finger protein 16 [ Phf16]) were upregulated while two genes (G0/G1 switch gene 2 [ G0s2] and patatin-like phospholipase domain containing 3 [ Pnpla3]) were downregulated by these four antiadipogenic compounds. Tissue expression profiles showed that the G0s2 and Pnpla3 expressions were highly specific to adipose depots while the other three induced genes were ubiquitously expressed with significantly higher expression in adipose tissues. While Cxcl1 expression was decreased, expressions of the other four genes were significantly increased during adipogenic differentiation of C3H10T1/2 cells. Small interfering RNA-mediated knockdown including Phf16 and Pnpla3 indicated that these genes might play regulatory roles in lipid accumulation and adipocyte differentiation. Specifically, the silencing of two newly identified adipogenic genes, Phf16 or Pnpla3, suppressed lipid accumulation and expression of adipocyte markers in both 3T3-L1 and C3H10T1/2 cells. Taken together, these data showed previously uncovered roles of Phf16 and Pnpla3 in adipogenesis, highlighting the potential of using phytochemicals for further investigation of adipocyte biology.
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Affiliation(s)
- Seo-Hyuk Chang
- Department of Food Science and Biotechnology, Sungkyunkwan University, Suwon, Korea
| | - Ui Jeong Yun
- Department of Food Science and Biotechnology, Sungkyunkwan University, Suwon, Korea
| | - Jin Hee Choi
- Department of Food Science and Biotechnology, Sungkyunkwan University, Suwon, Korea
| | - Suji Kim
- Department of Food Science and Biotechnology, Sungkyunkwan University, Suwon, Korea
| | - A Reum Lee
- Department of Food Science and Biotechnology, Sungkyunkwan University, Suwon, Korea
| | - Dong Ho Lee
- Department of Food Science and Biotechnology, Sungkyunkwan University, Suwon, Korea
| | - Min-Ju Seo
- Department of Food Science and Biotechnology, Sungkyunkwan University, Suwon, Korea
| | - Vanja Panic
- Department of Biochemistry, School of Medicine, University of Utah, Salt Lake City, Utah
| | - Claudio J Villanueva
- Department of Biochemistry, School of Medicine, University of Utah, Salt Lake City, Utah
| | - No-Joon Song
- Department of Food Science and Biotechnology, Sungkyunkwan University, Suwon, Korea
| | - Kye Won Park
- Department of Food Science and Biotechnology, Sungkyunkwan University, Suwon, Korea
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16
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Karanth S, Adams JD, Serrano MDLA, Quittner-Strom EB, Simcox J, Villanueva CJ, Ozcan L, Holland WL, Yost HJ, Vella A, Schlegel A. A Hepatocyte FOXN3-α Cell Glucagon Axis Regulates Fasting Glucose. Cell Rep 2018; 24:312-319. [PMID: 29996093 DOI: 10.1016/j.celrep.2018.06.039] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [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: 02/07/2018] [Revised: 05/07/2018] [Accepted: 06/08/2018] [Indexed: 01/26/2023] Open
Abstract
The common genetic variation at rs8004664 in the FOXN3 gene is independently and significantly associated with fasting blood glucose, but not insulin, in non-diabetic humans. Recently, we reported that primary hepatocytes from rs8004664 hyperglycemia risk allele carriers have increased FOXN3 transcript and protein levels and liver-limited overexpression of human FOXN3, a transcriptional repressor that had not been implicated in metabolic regulation previously, increases fasting blood glucose in zebrafish. Here, we find that injection of glucagon into mice and adult zebrafish decreases liver Foxn3 protein and transcript levels. Zebrafish foxn3 loss-of-function mutants have decreased fasting blood glucose, blood glucagon, liver gluconeogenic gene expression, and α cell mass. Conversely, liver-limited overexpression of foxn3 increases α cell mass. Supporting these genetic findings in model organisms, non-diabetic rs8004664 risk allele carriers have decreased suppression of glucagon during oral glucose tolerance testing. By reciprocally regulating each other, liver FOXN3 and glucagon control fasting glucose.
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Affiliation(s)
- Santhosh Karanth
- University of Utah Molecular Medicine Program, University of Utah School of Medicine, Salt Lake City, UT, USA; Department of Internal Medicine, Division of Endocrinology, Metabolism and Diabetes, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - J D Adams
- Department of Internal Medicine, Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Maria de Los Angeles Serrano
- University of Utah Molecular Medicine Program, University of Utah School of Medicine, Salt Lake City, UT, USA; Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Ezekiel B Quittner-Strom
- University of Utah Molecular Medicine Program, University of Utah School of Medicine, Salt Lake City, UT, USA; Department of Nutrition and Integrative Physiology, University of Utah College of Health, Salt Lake City, UT, USA
| | - Judith Simcox
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Claudio J Villanueva
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Lale Ozcan
- Department of Medicine, Division of Molecular Medicine, Columbia University Medical Center, New York, NY, USA
| | - William L Holland
- University of Utah Molecular Medicine Program, University of Utah School of Medicine, Salt Lake City, UT, USA; Department of Nutrition and Integrative Physiology, University of Utah College of Health, Salt Lake City, UT, USA; Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - H Joseph Yost
- University of Utah Molecular Medicine Program, University of Utah School of Medicine, Salt Lake City, UT, USA; Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT, USA; Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Adrian Vella
- Department of Internal Medicine, Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Amnon Schlegel
- University of Utah Molecular Medicine Program, University of Utah School of Medicine, Salt Lake City, UT, USA; Department of Internal Medicine, Division of Endocrinology, Metabolism and Diabetes, University of Utah School of Medicine, Salt Lake City, UT, USA; Department of Nutrition and Integrative Physiology, University of Utah College of Health, Salt Lake City, UT, USA; Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA.
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17
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Sommakia S, Houlihan PR, Deane SS, Simcox JA, Torres NS, Jeong MY, Winge DR, Villanueva CJ, Chaudhuri D. Mitochondrial cardiomyopathies feature increased uptake and diminished efflux of mitochondrial calcium. J Mol Cell Cardiol 2017; 113:22-32. [PMID: 28962857 DOI: 10.1016/j.yjmcc.2017.09.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 09/07/2017] [Accepted: 09/25/2017] [Indexed: 12/26/2022]
Abstract
Calcium (Ca2+) influx into the mitochondrial matrix stimulates ATP synthesis. Here, we investigate whether mitochondrial Ca2+ transport pathways are altered in the setting of deficient mitochondrial energy synthesis, as increased matrix Ca2+ may provide a stimulatory boost. We focused on mitochondrial cardiomyopathies, which feature such dysfunction of oxidative phosphorylation. We study a mouse model where the main transcription factor for mitochondrial DNA (transcription factor A, mitochondrial, Tfam) has been disrupted selectively in cardiomyocytes. By the second postnatal week (10-15day old mice), these mice have developed a dilated cardiomyopathy associated with impaired oxidative phosphorylation. We find evidence of increased mitochondrial Ca2+ during this period using imaging, electrophysiology, and biochemistry. The mitochondrial Ca2+ uniporter, the main portal for Ca2+ entry, displays enhanced activity, whereas the mitochondrial sodium-calcium (Na+-Ca2+) exchanger, the main portal for Ca2+ efflux, is inhibited. These changes in activity reflect changes in protein expression of the corresponding transporter subunits. While decreased transcription of Nclx, the gene encoding the Na+-Ca2+ exchanger, explains diminished Na+-Ca2+ exchange, the mechanism for enhanced uniporter expression appears to be post-transcriptional. Notably, such changes allow cardiac mitochondria from Tfam knockout animals to be far more sensitive to Ca2+-induced increases in respiration. In the absence of Ca2+, oxygen consumption declines to less than half of control values in these animals, but rebounds to control levels when incubated with Ca2+. Thus, we demonstrate a phenotype of enhanced mitochondrial Ca2+ in a mitochondrial cardiomyopathy model, and show that such Ca2+ accumulation is capable of rescuing deficits in energy synthesis capacity in vitro.
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Affiliation(s)
- Salah Sommakia
- Nora Eccles Harrison Cardiovascular Research and Training Institute, Cardiology Division, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
| | - Patrick R Houlihan
- Department of Cardiology, Boston Children's Hospital, Boston, MA, United States
| | - Sadiki S Deane
- Nora Eccles Harrison Cardiovascular Research and Training Institute, Cardiology Division, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
| | - Judith A Simcox
- Department of Biochemistry, University of Utah, Salt Lake City, UT, United States
| | - Natalia S Torres
- Nora Eccles Harrison Cardiovascular Research and Training Institute, Cardiology Division, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
| | - Mi-Young Jeong
- Department of Biochemistry, University of Utah, Salt Lake City, UT, United States; Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
| | - Dennis R Winge
- Department of Biochemistry, University of Utah, Salt Lake City, UT, United States; Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
| | - Claudio J Villanueva
- Department of Biochemistry, University of Utah, Salt Lake City, UT, United States
| | - Dipayan Chaudhuri
- Nora Eccles Harrison Cardiovascular Research and Training Institute, Cardiology Division, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States.
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18
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Simcox J, Geoghegan G, Maschek JA, Bensard CL, Pasquali M, Miao R, Lee S, Jiang L, Huck I, Kershaw EE, Donato AJ, Apte U, Longo N, Rutter J, Schreiber R, Zechner R, Cox J, Villanueva CJ. Global Analysis of Plasma Lipids Identifies Liver-Derived Acylcarnitines as a Fuel Source for Brown Fat Thermogenesis. Cell Metab 2017; 26:509-522.e6. [PMID: 28877455 PMCID: PMC5658052 DOI: 10.1016/j.cmet.2017.08.006] [Citation(s) in RCA: 157] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 04/27/2017] [Accepted: 08/08/2017] [Indexed: 12/30/2022]
Abstract
Cold-induced thermogenesis is an energy-demanding process that protects endotherms against a reduction in ambient temperature. Using non-targeted liquid chromatography-mass spectrometry-based lipidomics, we identified elevated levels of plasma acylcarnitines in response to the cold. We found that the liver undergoes a metabolic switch to provide fuel for brown fat thermogenesis by producing acylcarnitines. Cold stimulates white adipocytes to release free fatty acids that activate the nuclear receptor HNF4α, which is required for acylcarnitine production in the liver and adaptive thermogenesis. Once in circulation, acylcarnitines are transported to brown adipose tissue, while uptake into white adipose tissue and liver is blocked. Finally, a bolus of L-carnitine or palmitoylcarnitine rescues the cold sensitivity seen with aging. Our data highlight an elegant mechanism whereby white adipose tissue provides long-chain fatty acids for hepatic carnitilation to generate plasma acylcarnitines as a fuel source for peripheral tissues in mice.
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Affiliation(s)
- Judith Simcox
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Gisela Geoghegan
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - John Alan Maschek
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Claire L Bensard
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA; Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Marzia Pasquali
- Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT 84112, USA; Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Ren Miao
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Sanghoon Lee
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Lei Jiang
- Children's Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Ian Huck
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Erin E Kershaw
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Anthony J Donato
- Department of Exercise and Sport Science, Geriatric Research, Education, and Clinical Center, Veteran's Affairs Medical Center, Salt Lake City, UT 84112, USA
| | - Udayan Apte
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Nicola Longo
- Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT 84112, USA; Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Jared Rutter
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA; Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Renate Schreiber
- Institute of Molecular Biosciences, University of Graz, Heinrichstrasse 31, 8010 Graz, Austria
| | - Rudolf Zechner
- Institute of Molecular Biosciences, University of Graz, Heinrichstrasse 31, 8010 Graz, Austria
| | - James Cox
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Claudio J Villanueva
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
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19
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Song NJ, Chang SH, Li DY, Villanueva CJ, Park KW. Induction of thermogenic adipocytes: molecular targets and thermogenic small molecules. Exp Mol Med 2017; 49:e353. [PMID: 28684864 PMCID: PMC5565954 DOI: 10.1038/emm.2017.70] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [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: 11/26/2016] [Revised: 12/25/2016] [Accepted: 12/30/2016] [Indexed: 12/17/2022] Open
Abstract
Adipose tissue is a central metabolic organ that controls energy homeostasis of the whole body. White adipose tissue (WAT) stores excess energy in the form of triglycerides, whereas brown adipose tissue (BAT) dissipates energy in the form of heat through mitochondrial uncoupling protein 1 (Ucp1). A newly identified adipose tissue called 'beige fat' (BAT-like) is produced through a process called WAT browning. This tissue mainly resides in WAT depots and displays intermediate characteristics of both WAT and BAT. Since the recent discovery of BAT in the human body, along with the identification of molecular targets for BAT activation, stimulating energy expenditure has been considered as a great strategy to treat human obesity and metabolic diseases. Here we summarize recent findings regarding molecular targets and thermogenic small molecules that can stimulate BAT and increase energy expenditure, with an emphasis on possible therapeutic applications in humans.
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Affiliation(s)
- No-Joon Song
- Department of Food Science and Biotechnology, Sungkyunkwan University, Suwon, Korea
| | - Seo-Hyuk Chang
- Department of Food Science and Biotechnology, Sungkyunkwan University, Suwon, Korea
| | - Dean Y Li
- Department of Medicine, Program in Molecular Medicine, University of Utah, Salt Lake City, UT, USA
| | - Claudio J Villanueva
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Kye Won Park
- Department of Food Science and Biotechnology, Sungkyunkwan University, Suwon, Korea
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20
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Wang J, Rajbhandari P, Damianov A, Han A, Sallam T, Waki H, Villanueva CJ, Lee SD, Nielsen R, Mandrup S, Reue K, Young SG, Whitelegge J, Saez E, Black DL, Tontonoz P. RNA-binding protein PSPC1 promotes the differentiation-dependent nuclear export of adipocyte RNAs. J Clin Invest 2017; 127:987-1004. [PMID: 28192372 DOI: 10.1172/jci89484] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 12/15/2016] [Indexed: 12/14/2022] Open
Abstract
A highly orchestrated gene expression program establishes the properties that define mature adipocytes, but the contribution of posttranscriptional factors to the adipocyte phenotype is poorly understood. Here we have shown that the RNA-binding protein PSPC1, a component of the paraspeckle complex, promotes adipogenesis in vitro and is important for mature adipocyte function in vivo. Cross-linking and immunoprecipitation followed by RNA sequencing revealed that PSPC1 binds to intronic and 3'-untranslated regions of a number of adipocyte RNAs, including the RNA encoding the transcriptional regulator EBF1. Purification of the paraspeckle complex from adipocytes further showed that PSPC1 associates with the RNA export factor DDX3X in a differentiation-dependent manner. Remarkably, PSPC1 relocates from the nucleus to the cytoplasm during differentiation, coinciding with enhanced export of adipogenic RNAs. Mice lacking PSPC1 in fat displayed reduced lipid storage and adipose tissue mass and were resistant to diet-induced obesity and insulin resistance due to a compensatory increase in energy expenditure. These findings highlight a role for PSPC1-dependent RNA maturation in the posttranscriptional control of adipose development and function.
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21
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Drew BG, Hamidi H, Zhou Z, Villanueva CJ, Krum SA, Calkin AC, Parks BW, Ribas V, Kalajian NY, Phun J, Daraei P, Christofk HR, Hewitt SC, Korach KS, Tontonoz P, Lusis AJ, Slamon DJ, Hurvitz SA, Hevener AL. Estrogen receptor (ER)α-regulated lipocalin 2 expression in adipose tissue links obesity with breast cancer progression. J Biol Chem 2014; 290:5566-81. [PMID: 25468909 DOI: 10.1074/jbc.m114.606459] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Obesity is associated with increased breast cancer (BrCA) incidence. Considering that inactivation of estrogen receptor (ER)α promotes obesity and metabolic dysfunction in women and female mice, understanding the mechanisms and tissue-specific sites of ERα action to combat metabolic-related disease, including BrCA, is of clinical importance. To study the role of ERα in adipose tissue we generated fat-specific ERα knock-out (FERKO) mice. Herein we show that ERα deletion increased adipocyte size, fat pad weight, and tissue expression and circulating levels of the secreted glycoprotein, lipocalin 2 (Lcn2), an adipokine previously associated with BrCA development. Chromatin immunoprecipitation and luciferase reporter studies showed that ERα binds the Lcn2 promoter to repress its expression. Because adipocytes constitute an important cell type of the breast microenvironment, we examined the impact of adipocyte ERα deletion on cancer cell behavior. Conditioned medium from ERα-null adipocytes and medium containing pure Lcn2 increased proliferation and migration of a subset of BrCA cells in culture. The proliferative and promigratory effects of ERα-deficient adipocyte-conditioned medium on BrCA cells was reversed by Lcn2 deletion. BrCA cell responsiveness to exogenous Lcn2 was heightened in cell types where endogenous Lcn2 expression was minimal, but components of the Lcn2 signaling pathway were enriched, i.e. SLC22A17 and 3-hydroxybutyrate dehydrogenase (BDH2). In breast tumor biopsies from women diagnosed with BrCA we found that BDH2 expression was positively associated with adiposity and circulating Lcn2 levels. Collectively these data suggest that reduction of ERα expression in adipose tissue promotes adiposity and is linked with the progression and severity of BrCA via increased adipocyte-specific Lcn2 production and enhanced tumor cell Lcn2 sensitivity.
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Affiliation(s)
- Brian G Drew
- From the David Geffen School of Medicine, Department of Medicine, Division of Endocrinology, Diabetes and Hypertension
| | - Habib Hamidi
- Division of Hematology-Oncology, and Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, California 90095
| | - Zhenqi Zhou
- From the David Geffen School of Medicine, Department of Medicine, Division of Endocrinology, Diabetes and Hypertension
| | - Claudio J Villanueva
- the Department of Pathology and Laboratory Medicine, Howard Hughes Medical Institute, UCLA, Los Angeles, California 90095
| | - Susan A Krum
- the Orthopaedic Hospital Department of Orthopaedic Surgery and the Orthopaedic Hospital Research Center, UCLA, Los Angeles, California 90095
| | - Anna C Calkin
- the Department of Pathology and Laboratory Medicine, Howard Hughes Medical Institute, UCLA, Los Angeles, California 90095
| | | | - Vicent Ribas
- From the David Geffen School of Medicine, Department of Medicine, Division of Endocrinology, Diabetes and Hypertension
| | - Nareg Y Kalajian
- From the David Geffen School of Medicine, Department of Medicine, Division of Endocrinology, Diabetes and Hypertension
| | - Jennifer Phun
- From the David Geffen School of Medicine, Department of Medicine, Division of Endocrinology, Diabetes and Hypertension
| | - Pedram Daraei
- From the David Geffen School of Medicine, Department of Medicine, Division of Endocrinology, Diabetes and Hypertension
| | - Heather R Christofk
- Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, California 90095, Molecular and Medical Pharmacology, UCLA, Los Angeles, California 90095
| | - Sylvia C Hewitt
- the Receptor Biology Section, Reproductive and Developmental Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709, and
| | - Kenneth S Korach
- the Receptor Biology Section, Reproductive and Developmental Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709, and
| | - Peter Tontonoz
- the Department of Pathology and Laboratory Medicine, Howard Hughes Medical Institute, UCLA, Los Angeles, California 90095
| | | | - Dennis J Slamon
- Division of Hematology-Oncology, and Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, California 90095, the Translational Research in Oncology-US
| | - Sara A Hurvitz
- Division of Hematology-Oncology, and Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, California 90095, the Translational Research in Oncology-US
| | - Andrea L Hevener
- From the David Geffen School of Medicine, Department of Medicine, Division of Endocrinology, Diabetes and Hypertension, Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, California 90095, Iris Cantor-UCLA Women's Health Center, Los Angeles, California 90095
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22
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Villanueva CJ, Vergnes L, Wang J, Drew BG, Hong C, Tu Y, Hu Y, Peng X, Xu F, Saez E, Wroblewski K, Hevener AL, Reue K, Fong LG, Young SG, Tontonoz P. Adipose subtype-selective recruitment of TLE3 or Prdm16 by PPARγ specifies lipid storage versus thermogenic gene programs. Cell Metab 2013; 17:423-35. [PMID: 23473036 PMCID: PMC3626567 DOI: 10.1016/j.cmet.2013.01.016] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [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: 09/13/2012] [Revised: 12/19/2012] [Accepted: 01/23/2013] [Indexed: 11/27/2022]
Abstract
Transcriptional effectors of white adipocyte-selective gene expression have not been described. Here we show that TLE3 is a white-selective cofactor that acts reciprocally with the brown-selective cofactor Prdm16 to specify lipid storage and thermogenic gene programs. Occupancy of TLE3 and Prdm16 on certain promoters is mutually exclusive, due to the ability of TLE3 to disrupt the physical interaction between Prdm16 and PPARγ. When expressed at elevated levels in brown fat, TLE3 counters Prdm16, suppressing brown-selective genes and inducing white-selective genes, resulting in impaired fatty acid oxidation and thermogenesis. Conversely, mice lacking TLE3 in adipose tissue show enhanced thermogenesis in inguinal white adipose depots and are protected from age-dependent deterioration of brown adipose tissue function. Our results suggest that the establishment of distinct adipocyte phenotypes with different capacities for thermogenesis and lipid storage is accomplished in part through the cell-type-selective recruitment of TLE3 or Prdm16 to key adipocyte target genes.
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23
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Zhang Q, Ramlee MK, Brunmeir R, Villanueva CJ, Halperin D, Xu F. Dynamic and distinct histone modifications modulate the expression of key adipogenesis regulatory genes. Cell Cycle 2012; 11:4310-22. [PMID: 23085542 DOI: 10.4161/cc.22224] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Histone modifications and their modifying enzymes are fundamentally involved in the epigenetic regulation of adipogenesis. This study aimed to define the roles of various histone modifications and their "division of labor" in fat cell differentiation. To achieve these goals, we examined the distribution patterns of eight core histone modifications at five key adipogenic regulatory genes, Pref-1, C/EBPβ, C/EBPα, PPARγ2 and aP2, during the adipogenesis of C3H 10T1/2 mouse mesenchymal stem cells (MSCs) and 3T3-L1 preadipocytes. We found that the examined histone modifications are globally stable throughout adipogenesis but show distinct and highly dynamic distribution patterns at specific genes. For example, the Pref-1 gene has lower levels of active chromatin markers and significantly higher H3 K27 tri-methylation in MSCs compared with committed preadipocytes; the C/EBPβ gene is enriched in active chromatin markers at its 3'-UTR; the C/EBPα gene is predominantly marked by H3 K27 tri-methylation in adipogenic precursor cells, and this repressive marker decreases dramatically upon induction; the PPARγ2 and aP2 genes show increased histone acetylation on both H3 and H4 tails during adipogenesis. Further functional studies revealed that the decreased level of H3 K27 tri-methylation leads to de-repression of Pref-1 gene, while the increased level of histone acetylation activates the transcription of PPARγ2 and aP2 genes. Moreover, the active histone modification-marked 3'-UTR of C/EBPβ gene was demonstrated as a strong enhancer element by luciferase assay. Our results indicate that histone modifications are gene-specific at adipogenic regulator genes, and they play distinct roles in regulating the transcriptional network during adipogenesis.
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Affiliation(s)
- Qiongyi Zhang
- Growth, Development and Metabolism Programme; Singapore Institute for Clinical Sciences; A*STAR; Singapore
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24
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Villanueva CJ, Waki H, Godio C, Nielsen R, Chou WL, Vargas L, Wroblewski K, Schmedt C, Chao LC, Boyadjian R, Mandrup S, Hevener A, Saez E, Tontonoz P. TLE3 is a dual-function transcriptional coregulator of adipogenesis. Cell Metab 2011; 13:413-427. [PMID: 21459326 PMCID: PMC3089971 DOI: 10.1016/j.cmet.2011.02.014] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [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: 08/12/2010] [Revised: 11/25/2010] [Accepted: 01/06/2011] [Indexed: 12/28/2022]
Abstract
PPARγ and Wnt signaling are central positive and negative regulators of adipogenesis, respectively. Here we identify the groucho family member TLE3 as a transcriptional integrator of the PPARγ and Wnt pathways. TLE3 is a direct target of PPARγ that participates in a feed-forward loop during adipocyte differentiation. TLE3 enhances PPARγ activity and functions synergistically with PPARγ on its target promoters to stimulate adipogenesis. At the same time, induction of TLE3 during differentiation provides a mechanism for termination of Wnt signaling. TLE3 antagonizes TCF4 activation by β-catenin in preadipocytes, thereby inhibiting Wnt target gene expression and reversing β-catenin-dependent repression of adipocyte gene expression. Transgenic expression of TLE3 in adipose tissue in vivo mimics the effects of PPARγ agonist and ameliorates high-fat-diet-induced insulin resistance. Our data suggest that TLE3 acts as a dual-function switch, driving the formation of both active and repressive transcriptional complexes that facilitate the adipogenic program.
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Affiliation(s)
- Claudio J Villanueva
- Howard Hughes Medical Institute and Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Hironori Waki
- Howard Hughes Medical Institute and Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Cristina Godio
- Department of Chemical Physiology, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Ronni Nielsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
| | - Wen-Ling Chou
- Department of Chemical Physiology, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Leo Vargas
- Genomics Institute of the Novartis Research Foundation, San Diego, CA 92121, USA
| | - Kevin Wroblewski
- Howard Hughes Medical Institute and Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Christian Schmedt
- Genomics Institute of the Novartis Research Foundation, San Diego, CA 92121, USA
| | - Lily C Chao
- Howard Hughes Medical Institute and Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Rima Boyadjian
- Howard Hughes Medical Institute and Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Susanne Mandrup
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
| | - Andrea Hevener
- Department of Medicine, Division of Endocrinology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Enrique Saez
- Department of Chemical Physiology, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
| | - Peter Tontonoz
- Howard Hughes Medical Institute and Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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25
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Abstract
The mechanisms that direct cell-type-specific peroxisome proliferator-activated receptor (PPAR) gene programs are poorly understood. In this issue of Immunity, Szanto et al. (2010) identify signal transducer and activator of transcription 6 as a transcriptional switch that licenses PPARγ-dependent gene expression in macrophages and dendritic cells.
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Affiliation(s)
- Claudio J Villanueva
- Howard Hughes Medical Institute and Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
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26
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Villanueva CJ, Monetti M, Shih M, Zhou P, Watkins SM, Bhanot S, Farese RV. Specific role for acyl CoA:Diacylglycerol acyltransferase 1 (Dgat1) in hepatic steatosis due to exogenous fatty acids. Hepatology 2009; 50:434-42. [PMID: 19472314 PMCID: PMC3097135 DOI: 10.1002/hep.22980] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
UNLABELLED Nonalcoholic fatty liver disease, characterized by the accumulation of triacylglycerols (TGs) and other lipids in the liver, often accompanies obesity and is a risk factor for nonalcoholic steatohepatitis and fibrosis. To treat or prevent fatty liver, a thorough understanding of hepatic fatty acid and TG metabolism is crucial. To investigate the role of acyl CoA:diacylglycerol acyltransferase 1 (DGAT1), a key enzyme of TG synthesis, in fatty liver development, we studied mice with global and liver-specific knockout of Dgat1. DGAT1 was required for hepatic steatosis induced by a high-fat diet and prolonged fasting, which are both characterized by delivery of exogenous fatty acids to the liver. Studies in primary hepatocytes showed that DGAT1 deficiency protected against hepatic steatosis by reducing synthesis and increasing the oxidation of fatty acids. In contrast, lipodystrophy (aP2-SREBP-1c436) and liver X receptor activation (T0901317), which increase de novo fatty acid synthesis in liver, caused steatosis independently of DGAT1. Pharmacologic inhibition of Dgat1 with antisense oligonucleotides protected against fatty liver induced by a high-fat diet. CONCLUSION Our findings identify a specific role for hepatic DGAT1 in esterification of exogenous fatty acids and indicate that DGAT1 contributes to hepatic steatosis induced by this mechanism.
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Affiliation(s)
- Claudio J. Villanueva
- Gladstone Institute of Cardiovascular Disease, University of California, San Francisco, California 94158, Biomedical Sciences Graduate Program, University of California, San Francisco, California 94158
| | - Mara Monetti
- Gladstone Institute of Cardiovascular Disease, University of California, San Francisco, California 94158
| | - Michelle Shih
- Gladstone Institute of Cardiovascular Disease, University of California, San Francisco, California 94158, Biomedical Sciences Graduate Program, University of California, San Francisco, California 94158
| | - Ping Zhou
- Gladstone Institute of Cardiovascular Disease, University of California, San Francisco, California 94158
| | | | - Sanjay Bhanot
- Isis Pharmaceuticals, Inc., Carlsbad, California 92008
| | - Robert V. Farese
- Gladstone Institute of Cardiovascular Disease, University of California, San Francisco, California 94158, Department of Medicine and of Biochemistry & Biophysics, University of California, San Francisco, California 94158, Diabetes Center, University of California, San Francisco, California 94158, Biomedical Sciences Graduate Program, University of California, San Francisco, California 94158
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27
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Chao LC, Bensinger SJ, Villanueva CJ, Wroblewski K, Tontonoz P. Inhibition of adipocyte differentiation by Nur77, Nurr1, and Nor1. Mol Endocrinol 2008; 22:2596-608. [PMID: 18945812 PMCID: PMC2610364 DOI: 10.1210/me.2008-0161] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Members of the nuclear receptor 4A (NR4A) subgroup of nuclear receptors have been implicated in the regulation of glucose and lipid metabolism in insulin-sensitive tissues such as liver and skeletal muscle. However, their function in adipocytes is not well defined. Previous studies have reported that these receptors are rapidly up-regulated after treatment of 3T3-L1 preadipocytes with an adipogenic cocktail. We show here that although Nur77 expression is acutely induced by cAMP agonists in 3T3-L1 cells, it is not induced by other adipogenic stimuli, such as peroxisome proliferator-activated receptor-gamma ligands, nor is it induced during the differentiation of 3T3-F442A preadipocytes, suggesting that Nur77 induction is not an obligatory feature of preadipocyte differentiation. We further demonstrate that inflammatory signals that antagonize differentiation, such as TNFalpha and lipopolysaccharide, acutely induce Nur77 expression both in vitro and in vivo. We also show that NR4A expression in adipose tissue is responsive to fasting/refeeding. Retroviral transduction of each of the NR4A receptors (Nur77, Nurr1, and NOR1) into either 3T3-L1 or 3T3-F442A preadipocytes potently inhibits adipogenesis. Interestingly, NR4A-mediated inhibition of adipogenesis cannot be rescued by peroxisome proliferator-activated receptor-gamma overexpression or activation. Transcriptional profiling of Nur77-expressing preadipocytes led to the identification of gap-junction protein alpha1 (Gja1) and tolloid-like 1 (Tll1) as Nur77-responsive genes. Remarkably, retroviral expression of either Gja1 or Tll1 in 3T3-L1 preadipocytes also inhibited adipocyte differentiation, implicating these genes as potential mediators of Nur77's effects on adipogenesis. Finally, we show that Nur77 expression inhibits mitotic clonal expansion of preadipocytes, providing an additional mechanism by which Nur77 may inhibit adipogenesis.
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Affiliation(s)
- Lily C Chao
- Howard Hughes Medical Institute, Department of Pathology and Laboratory Medicine, University of California, Los Angeles, California 90095-1662, USA
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28
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Park KW, Waki H, Villanueva CJ, Monticelli LA, Hong C, Kang S, MacDougald OA, Goldrath AW, Tontonoz P. Inhibitor of DNA binding 2 is a small molecule-inducible modulator of peroxisome proliferator-activated receptor-gamma expression and adipocyte differentiation. Mol Endocrinol 2008; 22:2038-48. [PMID: 18562627 PMCID: PMC2631374 DOI: 10.1210/me.2007-0454] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We previously identified the small molecule harmine as a regulator of peroxisome proliferator activated-receptor gamma (PPARgamma) and adipocyte differentiation. In an effort to identify signaling pathways mediating harmine's effects, we performed transcriptional profiling of 3T3-F442A preadipocytes. Inhibitor of DNA biding 2 (Id2) was identified as a gene rapidly induced by harmine but not by PPARgamma agonists. Id2 is also induced in 3T3-L1 preadipocytes treated with dexamethasone, 3-isobutyl-1-methylxanthine, and insulin, suggesting that Id2 regulation is a common feature of the adipogenic program. Stable overexpression of Id2 in preadipocytes promotes expression of PPARgamma and enhances morphological differentiation and lipid accumulation. Conversely, small interfering RNA-mediated knockdown of Id2 antagonizes adipocyte differentiation. Mice lacking Id2 expression display reduced adiposity, and embryonic fibroblasts derived from these mice exhibit reduced PPARgamma expression and a diminished capacity for adipocyte differentiation. Finally, Id2 expression is elevated in adipose tissues of obese mice and humans. These results outline a role for Id2 in the modulation of PPARgamma expression and adipogenesis and underscore the utility of adipogenic small molecules as tools to dissect adipocyte biology.
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Affiliation(s)
- Kye Won Park
- Howard Hughes Medical Institute, University of California, Los Angeles, California 90095, USA
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29
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Minehira K, Young SG, Villanueva CJ, Yetukuri L, Oresic M, Hellerstein MK, Farese RV, Horton JD, Preitner F, Thorens B, Tappy L. Blocking VLDL secretion causes hepatic steatosis but does not affect peripheral lipid stores or insulin sensitivity in mice. J Lipid Res 2008; 49:2038-44. [PMID: 18515909 DOI: 10.1194/jlr.m800248-jlr200] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The liver secretes triglyceride-rich VLDLs, and the triglycerides in these particles are taken up by peripheral tissues, mainly heart, skeletal muscle, and adipose tissue. Blocking hepatic VLDL secretion interferes with the delivery of liver-derived triglycerides to peripheral tissues and results in an accumulation of triglycerides in the liver. However, it is unclear how interfering with hepatic triglyceride secretion affects adiposity, muscle triglyceride stores, and insulin sensitivity. To explore these issues, we examined mice that cannot secrete VLDL [due to the absence of microsomal triglyceride transfer protein (Mttp) in the liver]. These mice exhibit markedly reduced levels of apolipoprotein B-100 in the plasma, along with reduced levels of triglycerides in the plasma. Despite the low plasma triglyceride levels, triglyceride levels in skeletal muscle were unaffected. Adiposity and adipose tissue triglyceride synthesis rates were also normal, and body weight curves were unaffected. Even though the blockade of VLDL secretion caused hepatic steatosis accompanied by increased ceramides and diacylglycerols in the liver, the mice exhibited normal glucose tolerance and were sensitive to insulin at the whole-body level, as judged by hyperinsulinemic euglycemic clamp studies. Normal hepatic glucose production and insulin signaling were also maintained in the fatty liver induced by Mttp deletion. Thus, blocking VLDL secretion causes hepatic steatosis without insulin resistance, and there is little effect on muscle triglyceride stores or adiposity.
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Affiliation(s)
- Kaori Minehira
- Gladstone Institute of Cardiovascular Disease, University of California-San Francisco, CA 94158, USA.
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Abstract
Mice lacking acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1), an enzyme that catalyzes the terminal step in triacylglycerol synthesis, have enhanced insulin sensitivity and are protected from obesity, a result of increased energy expenditure. In these mice, factors derived from white adipose tissue (WAT) contribute to the systemic changes in metabolism. One such factor, adiponectin, increases fatty acid oxidation and enhances insulin sensitivity. To test the hypothesis that adiponectin is required for the altered energy and glucose metabolism in DGAT1-deficient mice, we generated adiponectin-deficient mice and introduced adiponectin deficiency into DGAT1-deficient mice by genetic crosses. Although adiponectin-deficient mice fed a high-fat diet were heavier, exhibited worse glucose tolerance, and had more hepatic triacylglycerol accumulation than wild-type controls, mice lacking both DGAT1 and adiponectin, like DGAT1-deficient mice, were protected from diet-induced obesity, glucose intolerance, and hepatic steatosis. These findings indicate that adiponectin is required for normal energy, glucose, and lipid metabolism but that the metabolic changes induced by DGAT1-deficient WAT are independent of adiponectin and are likely due to other WAT-derived factors. Our findings also suggest that the pharmacological inhibition of DGAT1 may be useful for treating human obesity and insulin resistance associated with low circulating adiponectin levels.
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Affiliation(s)
- Ryan S. Streeper
- Gladstone Institute of Cardiovascular Disease
- Cardiovascular Research Institute and
| | - Suneil K. Koliwad
- Gladstone Institute of Cardiovascular Disease
- Cardiovascular Research Institute and
- Departments of Medicine and
| | | | - Robert V. Farese
- Gladstone Institute of Cardiovascular Disease
- Cardiovascular Research Institute and
- Departments of Medicine and
- Biochemistry and Biophysics, and
- The Diabetes Center, University of California, San Francisco, California
- Address for reprint requests and other correspondence: Robert V. Farese, Jr., Gladstone Institute of Cardiovascular Disease, 1650 Owens St., San Francisco, CA 94158 (e-mail: )
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