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Translational advances of melanocortin drugs: Integrating biology, chemistry and genetics. Semin Immunol 2022; 59:101603. [PMID: 35341670 DOI: 10.1016/j.smim.2022.101603] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 03/10/2022] [Accepted: 03/15/2022] [Indexed: 01/15/2023]
Abstract
Melanocortin receptors have emerged as important targets with a very unusual versatility, as their widespread distribution on multiple tissues (e.g. skin, adrenal glands, brain, immune cells, exocrine glands) together with the variety of physiological processes they control (pigmentation, cortisol release, satiety mechanism, inflammation, secretions), place this family of receptors as genuine therapeutic targets for many disorders. This review focuses in the journey of the development of melanocortin receptors as therapeutic targets from the discovery of their existence in the early 1990 s to the approval of the first few drugs of this class. Two major areas of development characterise the current state of melanocortin drug development: their role in obesity, recently culminated with the approval of setmelanotide, and their potential for the treatment of chronic inflammatory and autoimmune diseases like rheumatoid arthritis, multiple sclerosis or fibrosis. The pro-resolving nature of these drugs offers the advantage of acting by mimicking the way our body naturally resolves inflammation, expecting fewer side effects and a more balanced (i.e. non-immunosuppressive) response from them. Here we also review the approaches followed for the design and development of novel compounds, the importance of the GPCR nature of these receptors in the process of drug development, therapeutic value, current challenges and successes, and the potential for the implementation of precision medicine approaches through the incorporation of genetics advances.
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2
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Morello G, Imperatore R, Palomba L, Finelli C, Labruna G, Pasanisi F, Sacchetti L, Buono L, Piscitelli F, Orlando P, Di Marzo V, Cristino L. Orexin-A represses satiety-inducing POMC neurons and contributes to obesity via stimulation of endocannabinoid signaling. Proc Natl Acad Sci U S A 2016; 113:4759-64. [PMID: 27071101 PMCID: PMC4855580 DOI: 10.1073/pnas.1521304113] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In the hypothalamic arcuate nucleus (ARC), proopiomelanocortin (POMC) neurons and the POMC-derived peptide α-melanocyte-stimulating hormone (α-MSH) promote satiety. POMC neurons receive orexin-A (OX-A)-expressing inputs and express both OX-A receptor type 1 (OX-1R) and cannabinoid receptor type 1 (CB1R) on the plasma membrane. OX-A is crucial for the control of wakefulness and energy homeostasis and promotes, in OX-1R-expressing cells, the biosynthesis of the endogenous counterpart of marijuana's psychotropic and appetite-inducing component Δ(9)-tetrahydrocannabinol, i.e., the endocannabinoid 2-arachidonoylglycerol (2-AG), which acts at CB1R. We report that OX-A/OX-1R signaling at POMC neurons promotes 2-AG biosynthesis, hyperphagia, and weight gain by blunting α-MSH production via CB1R-induced and extracellular-signal-regulated kinase 1/2 activation- and STAT3 inhibition-mediated suppression of Pomc gene transcription. Because the systemic pharmacological blockade of OX-1R by SB334867 caused anorectic effects by reducing food intake and body weight, our results unravel a previously unsuspected role for OX-A in endocannabinoid-mediated promotion of appetite by combining OX-induced alertness with food seeking. Notably, increased OX-A trafficking was found in the fibers projecting to the ARC of obese mice (ob/ob and high-fat diet fed) concurrently with elevation of OX-A release in the cerebrospinal fluid and blood of mice. Furthermore, a negative correlation between OX-A and α-MSH serum levels was found in obese mice as well as in human obese subjects (body mass index > 40), in combination with elevation of alanine aminotransferase and γ-glutamyl transferase, two markers of fatty liver disease. These alterations were counteracted by antagonism of OX-1R, thus providing the basis for a therapeutic treatment of these diseases.
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Affiliation(s)
- Giovanna Morello
- Institute of Biomolecular Chemistry, National Research Council, 80078 Pozzuoli, Italy; Department of Neurological and Movement Sciences, University of Verona, 37137 Verona, Italy
| | - Roberta Imperatore
- Institute of Biomolecular Chemistry, National Research Council, 80078 Pozzuoli, Italy
| | - Letizia Palomba
- Department of Biomolecular Sciences, University of Urbino "Carlo Bo," 61029 Urbino, Italy
| | - Carmine Finelli
- Interuniversity Center for Research and Study of Obesity, Department of Clinical and Experimental Medicine, Federico II University Hospital, 80131 Naples, Italy
| | - Giuseppe Labruna
- Istituto di Ricovero e Cura a Carattere Scientifico, Institute of Diagnostic and Nuclear Research, 80131 Naples, Italy
| | - Fabrizio Pasanisi
- Interuniversity Center for Research and Study of Obesity, Department of Clinical and Experimental Medicine, Federico II University Hospital, 80131 Naples, Italy
| | - Lucia Sacchetti
- Centro di Ingegneria Genetica-Advanced Biotechnology (Società Cooperativa a Responsabilità Limitata), 80131 Naples, Italy
| | - Lorena Buono
- Institute of Biomolecular Chemistry, National Research Council, 80078 Pozzuoli, Italy; Centro de Biología Molecular "Severo Ochoa," Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, 28049 Cantoblanco, Spain
| | - Fabiana Piscitelli
- Institute of Biomolecular Chemistry, National Research Council, 80078 Pozzuoli, Italy
| | - Pierangelo Orlando
- Institute of Protein Biochemistry, National Research Council, 80131 Naples, Italy
| | - Vincenzo Di Marzo
- Institute of Biomolecular Chemistry, National Research Council, 80078 Pozzuoli, Italy
| | - Luigia Cristino
- Institute of Biomolecular Chemistry, National Research Council, 80078 Pozzuoli, Italy;
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Abstract
Obesity is the result of a long-standing imbalance between energy intake and energy expenditure, aided by a complex biologic system that regulates appetite and favors intake. New knowledge about substances that stimulate or inhibit appetite offers hope that drug-based solutions will be found for the current high prevalence of obesity in the United States. In this article, Dr Bessesen highlights some of the new molecular and genetic discoveries related to obesity and outlines the hypothalamic neural pathways involved in regulating food intake.
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Affiliation(s)
- Daniel H Bessesen
- Denver Health Medical Center, Mail Code 4000, 777 Bannock St, Denver, CO 80204-4507, USA.
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Yang F, Tao YX. Functional characterization of nine novel naturally occurring human melanocortin-3 receptor mutations. Biochim Biophys Acta Mol Basis Dis 2012; 1822:1752-61. [PMID: 22884546 DOI: 10.1016/j.bbadis.2012.07.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2012] [Revised: 07/12/2012] [Accepted: 07/27/2012] [Indexed: 12/20/2022]
Abstract
The melanocortin-3 receptor (MC3R) is a member of family A rhodopsin-like G protein-coupled receptors. Mouse genetic studies suggested that MC3R and the related MC4R are non-redundant regulators of energy homeostasis. Lack of Mc3r leads to higher feed efficiency and fat mass. However, until now only a few MC3R mutations have been identified in humans and the role of MC3R in the pathogenesis of obesity was unclear. In the present study, we performed detailed functional studies on nine naturally occurring MC3R mutations recently reported. We found that all nine mutants had decreased cell surface expression. A260V, M275T, and L297V had decreased total expression whereas the other six mutants had normal total expression. Mutants S69C and T280S exhibited significant defects in ligand binding and signaling. The dramatic defects of T280S might be partially caused by decreased cell surface expression. In addition, we found mutants M134I and M275T had decreased maximal binding but displayed similar signaling properties as wild-type MC3R. All the other mutants had normal binding and signaling activities. Co-expression studies showed that all mutants except L297V did not affect wild-type MC3R signaling. Multiple mutations at T280 demonstrated the necessity of Thr for cell surface expression, ligand binding, and signaling. In summary, we provided detailed data of these novel human MC3R mutations leading to a better understanding of structure-function relationship of MC3R and the role of MC3R mutation in obesity.
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Affiliation(s)
- Fan Yang
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA
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5
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Tranah GJ, Lam ET, Katzman SM, Nalls MA, Zhao Y, Evans DS, Yokoyama JS, Pawlikowska L, Kwok PY, Mooney S, Kritchevsky S, Goodpaster BH, Newman AB, Harris TB, Manini TM, Cummings SR. Mitochondrial DNA sequence variation is associated with free-living activity energy expenditure in the elderly. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:1691-700. [PMID: 22659402 DOI: 10.1016/j.bbabio.2012.05.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 05/19/2012] [Accepted: 05/24/2012] [Indexed: 01/11/2023]
Abstract
The decline in activity energy expenditure underlies a range of age-associated pathological conditions, neuromuscular and neurological impairments, disability, and mortality. The majority (90%) of the energy needs of the human body are met by mitochondrial oxidative phosphorylation (OXPHOS). OXPHOS is dependent on the coordinated expression and interaction of genes encoded in the nuclear and mitochondrial genomes. We examined the role of mitochondrial genomic variation in free-living activity energy expenditure (AEE) and physical activity levels (PAL) by sequencing the entire (~16.5 kilobases) mtDNA from 138 Health, Aging, and Body Composition Study participants. Among the common mtDNA variants, the hypervariable region 2 m.185G>A variant was significantly associated with AEE (p=0.001) and PAL (p=0.0005) after adjustment for multiple comparisons. Several unique nonsynonymous variants were identified in the extremes of AEE with some occurring at highly conserved sites predicted to affect protein structure and function. Of interest is the p.T194M, CytB substitution in the lower extreme of AEE occurring at a residue in the Qi site of complex III. Among participants with low activity levels, the burden of singleton variants was 30% higher across the entire mtDNA and OXPHOS complex I when compared to those having moderate to high activity levels. A significant pooled variant association across the hypervariable 2 region was observed for AEE and PAL. These results suggest that mtDNA variation is associated with free-living AEE in older persons and may generate new hypotheses by which specific mtDNA complexes, genes, and variants may contribute to the maintenance of activity levels in late life.
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Affiliation(s)
- Gregory J Tranah
- California Pacific Medical Center Research Institute, San Francisco, San Francisco, CA 94107, USA.
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Zafón C. [Evolutionary endocrinology: a pending matter]. ACTA ACUST UNITED AC 2011; 59:62-8. [PMID: 22113050 DOI: 10.1016/j.endonu.2011.09.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 08/05/2011] [Accepted: 09/01/2011] [Indexed: 12/22/2022]
Abstract
Twenty years have passed since the foundational article of what is now known as evolutionary medicine (EM) was published. This young medical discipline examines, following Darwinian principles, susceptibility to certain diseases and how we react to them. In short, EM analyzes the final cause of the disease from a historical perspective. Over the years, EM has been introduced in various medical areas in very different ways. While it has found a role in some fields such as infectious diseases and oncology, its contribution in other areas has been quite limited. In endocrinology, EM has only gained prominence as a basis for the so-called "diseases of civilization", including diabetes mellitus and obesity. However, many experts suggest that it may have a much higher potential. The aim of this paper is to provide a view about what evolutionary medicine is. Some examples of how EM may contribute to progress of our specialty are also given. There is no doubt that evolution enriches medicine, but medicine also offers knowledge to evolution.
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Affiliation(s)
- Carles Zafón
- Servicio de Endocrinología y Nutrición, Hospital Universitari Vall d'Hebron, Barcelona, España.
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7
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Walter S, Atzmon G, Demerath EW, Garcia ME, Kaplan RC, Kumari M, Lunetta KL, Milaneschi Y, Tanaka T, Tranah GJ, Völker U, Yu L, Arnold A, Benjamin EJ, Biffar R, Buchman AS, Boerwinkle E, Couper D, De Jager PL, Evans DA, Harris TB, Hoffmann W, Hofman A, Karasik D, Kiel DP, Kocher T, Kuningas M, Launer LJ, Lohman KK, Lutsey PL, Mackenbach J, Marciante K, Psaty BM, Reiman EM, Rotter JI, Seshadri S, Shardell MD, Smith AV, van Duijn C, Walston J, Zillikens MC, Bandinelli S, Baumeister SE, Bennett DA, Ferrucci L, Gudnason V, Kivimaki M, Liu Y, Murabito JM, Newman AB, Tiemeier H, Franceschini N. A genome-wide association study of aging. Neurobiol Aging 2011; 32:2109.e15-28. [PMID: 21782286 PMCID: PMC3193030 DOI: 10.1016/j.neurobiolaging.2011.05.026] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 04/14/2011] [Accepted: 05/30/2011] [Indexed: 12/22/2022]
Abstract
Human longevity and healthy aging show moderate heritability (20%-50%). We conducted a meta-analysis of genome-wide association studies from 9 studies from the Cohorts for Heart and Aging Research in Genomic Epidemiology Consortium for 2 outcomes: (1) all-cause mortality, and (2) survival free of major disease or death. No single nucleotide polymorphism (SNP) was a genome-wide significant predictor of either outcome (p < 5 × 10(-8)). We found 14 independent SNPs that predicted risk of death, and 8 SNPs that predicted event-free survival (p < 10(-5)). These SNPs are in or near genes that are highly expressed in the brain (HECW2, HIP1, BIN2, GRIA1), genes involved in neural development and function (KCNQ4, LMO4, GRIA1, NETO1) and autophagy (ATG4C), and genes that are associated with risk of various diseases including cancer and Alzheimer's disease. In addition to considerable overlap between the traits, pathway and network analysis corroborated these findings. These findings indicate that variation in genes involved in neurological processes may be an important factor in regulating aging free of major disease and achieving longevity.
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Affiliation(s)
- Stefan Walter
- Department of Public Health, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Gil Atzmon
- Institute for Aging Research and the Diabetes Research Center. Albert Einstein College of Medicine, Bronx, NY, United States of America
- Department of Medicine Albert Einstein College of Medicine, Bronx, NY, United States of America
- Department of Genetic Albert Einstein College of Medicine, Bronx, NY, United States of America
| | - Ellen W. Demerath
- Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Melissa E. Garcia
- Laboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, National Institutes of Health, Bethesda, MD, United States of America
| | - Robert C. Kaplan
- Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx NY, United States of America
| | - Meena Kumari
- Department of Epidemiology and Public Health, University College London, London, United Kingdom
| | - Kathryn L. Lunetta
- Department of Biostatistics, Boston University School of Public Health, Boston, MA, United States of America
| | - Yuri Milaneschi
- Clinical Research Branch, National Institute on Aging, Baltimore, MD, United States of America
| | - Toshiko Tanaka
- Clinical Research Branch, National Institute on Aging, Baltimore, MD, United States of America
| | - Gregory J. Tranah
- California Pacific Medical Center, San Francisco, CA, United States of America
| | - Uwe Völker
- Interfaculty Institute for Genetics and Functional Genomics, Ernst-Moritz-Arndt-University Greifswald, Greifswald, Germany
| | - Lei Yu
- Rush Alzheimer’s Disease Center, Rush University Medical Center, Chicago, IL, United States of America
| | - Alice Arnold
- Department of Biostatistics, Unversity of Washington, Seattle, WA, United States of America
| | - Emelia J. Benjamin
- Sections of General Internal Medicine, Preventive Medicine, Cardiology and Neurology, Department of Medicine, Boston University School of Medicine, Boston, MA, United States of America
- The National Heart Lung and Blood Institute’s Framingham Heart Study, Framingham, MA, United States of America
| | - Reiner Biffar
- Dental School, Ernst-Moritz-Arndt-University Greifswald, Greifswald, Germany
| | - Aron S. Buchman
- Rush Alzheimer’s Disease Center, Rush University Medical Center, Chicago, IL, United States of America
| | - Eric Boerwinkle
- Human Genetics Center, University of Texas Health Science Center at Houston, Houston, Texas, United States of America
| | - David Couper
- Department of Biostatistics, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, United States of America
| | - Philip L. De Jager
- Program in Translational NeuroPsychiatric Genomics, Department of Neurology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Denis A. Evans
- Rush Institute for Healthy Aging, Rush University Medical Center, Chicago, IL, United States of America
| | - Tamara B. Harris
- Laboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, National Institutes of Health, Bethesda, MD, United States of America
| | - Wolfgang Hoffmann
- Institute of Community Medicine, Ernst-Moritz-Arndt-University Greifswald, Greifswald, Germany
- Center for Integrated Dementia Care Research (CIDC), a scientific cooperation between the Universities and University Hospitals of Rostock and Greifswald and the German Center for Neurodegenerative Disease (DZNE), Bonn, Germany
| | - Albert Hofman
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - David Karasik
- Hebrew SeniorLife Institute for Aging Research and Harvard Medical School, Boston, MA, United States of America
| | - Douglas P. Kiel
- Hebrew SeniorLife Institute for Aging Research and Harvard Medical School, Boston, MA, United States of America
| | - Thomas Kocher
- Dental School, Ernst-Moritz-Arndt-University Greifswald, Greifswald, Germany
| | - Maris Kuningas
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Lenore J. Launer
- Laboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, National Institutes of Health, Bethesda, MD, United States of America
| | - Kurt K. Lohman
- Center for Human Genomics, Department of Epidemiology and Prevention, Wake Forest University School of Medicine, Winston-Salem, NC, United States of America
| | - Pamela L. Lutsey
- Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Johan Mackenbach
- Department of Public Health, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Kristin Marciante
- Cardiovascular Health Research Unit, Departments of Medicine, Epidemiology, and Health Services, University of Washington, Seattle WA, United States of America
| | - Bruce M. Psaty
- Cardiovascular Health Research Unit, Departments of Medicine, Epidemiology, and Health Services, University of Washington, Seattle WA, United States of America
- Group Health Research Unit, Group Health Cooperative, Seattle, WA, United States of America
| | - Eric M. Reiman
- Neurogenomics Division, The Translational Genomics Research Institute, Banner Alzheimer’s Institute, Phoenix, AZ, United States of America
| | - Jerome I. Rotter
- Medical Genetics Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States of America
| | - Sudha Seshadri
- Sections of General Internal Medicine, Preventive Medicine, Cardiology and Neurology, Department of Medicine, Boston University School of Medicine, Boston, MA, United States of America
- The National Heart Lung and Blood Institute’s Framingham Heart Study, Framingham, MA, United States of America
| | - Michelle D. Shardell
- Epidemiology and Public Health, University of Maryland, MD, United States of America
| | | | - Cornelia van Duijn
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Jeremy Walston
- Johns Hopkins University School of Medicine Division of Geriatric Medicine and Gerontology, Baltimore, MD, United States of America
| | - M. Carola Zillikens
- Johns Hopkins University School of Medicine Division of Geriatric Medicine and Gerontology, Baltimore, MD, United States of America
| | | | - Sebastian E. Baumeister
- Institute of Community Medicine, Ernst-Moritz-Arndt-University Greifswald, Greifswald, Germany
| | - David A. Bennett
- Rush Alzheimer’s Disease Center, Rush University Medical Center, Chicago, IL, United States of America
| | - Luigi Ferrucci
- Clinical Research Branch, National Institute on Aging, Baltimore, MD, United States of America
| | | | - Mika Kivimaki
- Department of Epidemiology and Public Health, University College London, London, United Kingdom
| | - Yongmei Liu
- Center for Human Genomics, Department of Epidemiology and Prevention, Wake Forest University School of Medicine, Winston-Salem, NC, United States of America
| | - Joanne M. Murabito
- Sections of General Internal Medicine, Preventive Medicine, Cardiology and Neurology, Department of Medicine, Boston University School of Medicine, Boston, MA, United States of America
- The National Heart Lung and Blood Institute’s Framingham Heart Study, Framingham, MA, United States of America
| | - Anne B. Newman
- Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Henning Tiemeier
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Child and Adolescent Psychiatry, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Nora Franceschini
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, United States of America
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Wang Q, Levay K, Chanturiya T, Dvoriantchikova G, Anderson KL, Bianco SDC, Ueta CB, Molano RD, Pileggi A, Gurevich EV, Gavrilova O, Slepak VZ. Targeted deletion of one or two copies of the G protein β subunit Gβ5 gene has distinct effects on body weight and behavior in mice. FASEB J 2011; 25:3949-57. [PMID: 21804131 DOI: 10.1096/fj.11-190157] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We investigated the physiological role of Gβ5, a unique G protein β subunit that dimerizes with regulators of G protein signaling (RGS) proteins of the R7 family instead of Gγ. Gβ5 is essential for stability of these complexes, so that its knockout (KO)causes degradation of the entire Gβ5-R7 family. We report that the Gβ5-KO mice remain leaner than the wild type (WT) throughout their lifetime and are resistant to a high-fat diet. They have a 5-fold increase in locomotor activity, increased thermogenesis, and lower serum insulin, all of which correlate with a higher level of secreted epinephrine. Heterozygous (HET) mice are 2-fold more active than WT mice. Surprisingly, with respect to body weight, the HET mice display a phenotype opposite to that of the KO mice: by the age of 6 mo, they are ≥ 15% heavier than the WT and have increased adiposity, insulin resistance, and liver steatosis. These changes occur in HET mice fed a normal diet and without apparent hyperphagia, mimicking basic characteristics of human metabolic syndrome. We conclude that even a partial reduction in Gβ5-R7 level can perturb normal animal metabolism and behavior. Our data on Gβ5 haploinsufficient mice may explain earlier observations of genetic linkage between R7 family mutations and obesity in humans.
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Affiliation(s)
- Qiang Wang
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, 33136, USA
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9
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Molecular characterization of CART, AgRP, and MC4R genes and their expression with fasting and re-feeding in common carp (Cyprinus carpio). Mol Biol Rep 2011; 39:2215-23. [PMID: 21643748 DOI: 10.1007/s11033-011-0970-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2010] [Accepted: 05/26/2011] [Indexed: 02/01/2023]
Abstract
Cocaine and amphetamine-regulated transcript (CART), agouti-related proteins (AgRP) and Melanocortin 4 Receptor (MC4R) involves in the control of appetite. The genes were cloned and characterized, and their regulation was studied in common carp. The CARTI and CARTII genes encode 117- and 120-amino acids, respectively. The AgRP-1 and AgRP-2 genes encode 128- and 136-amino acids, respectively. CARTI was principally expressed in the brain, eye and ovary, while CARTII was highly expressed in the brain. AgRP-1 was strongly expressed in the brain, intestine, testis and eye, while AgRP-2 was highly expressed only in the gill and eye. The MC4R gene, encoding 326-amino acids, was mainly expressed in the brain testis, pituitary and eye. Phylogenetic analysis had been conducted which implied that both CARTI/CARTII and AgRP-1/AgRP-2 might derived from gene duplication events during genome evolution of common carp. CART, AgRP and MC4R gene expression in brain were decreased after fasting treatment and increased sharply after refeeding comparing with normal fed controls, which suggested that CART, AgRP and MC4R are involved in appetite regulation in common carp.
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Iqbal J, Li X, Chang BHJ, Chan L, Schwartz GJ, Chua SC, Hussain MM. An intrinsic gut leptin-melanocortin pathway modulates intestinal microsomal triglyceride transfer protein and lipid absorption. J Lipid Res 2010; 51:1929-42. [PMID: 20164094 DOI: 10.1194/jlr.m005744] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Fat is delivered to tissues by apoB-containing lipoproteins synthesized in the liver and intestine with the help of an intracellular chaperone, microsomal triglyceride transfer protein (MTP). Leptin, a hormone secreted by adipose tissue, acts in the brain and on peripheral tissues to regulate fat storage and metabolism. Our aim was to identify the role of leptin signaling in MTP regulation and lipid absorption using several mouse models deficient in leptin receptor (LEPR) signaling and downstream effectors. Mice with spontaneous LEPR B mutations or targeted ablation of LEPR B in proopiomelanocortin (POMC) or agouti gene related peptide (AGRP) expressing cells had increased triglyceride in plasma, liver, and intestine. Furthermore, melanocortin 4 receptor (MC4R) knockout mice expressed a similar triglyceride phenotype, suggesting that leptin might regulate intestinal MTP expression through the melanocortin pathway. Mechanistic studies revealed that the accumulation of triglyceride in the intestine might be secondary to decreased expression of MTP and lipid absorption in these mice. Surgical and chemical blockade of vagal efferent outflow to the intestine in wild-type mice failed to alter the triglyceride phenotype, demonstrating that central neural control mechanisms were likely not involved in the observed regulation of intestinal MTP. Instead, we found that enterocytes express LEPR, POMC, AGRP, and MC4R. We propose that a peripheral, local gut signaling mechanism involving LEPR B and MC4R regulates intestinal MTP and controls intestinal lipid absorption.
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Affiliation(s)
- Jahangir Iqbal
- Department of Cell Biology and Pediatrics, State University of New York Health Science Center at Brooklyn (SUNY Downstate Medical Center), Brooklyn, NY, USA
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11
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Santoro N, Cirillo G, Xiang Z, Tanas R, Greggio N, Morino G, Iughetti L, Vottero A, Salvatoni A, Di Pietro M, Balsamo A, Crinò A, Grandone A, Haskell-Luevano C, Perrone L, del Giudice EM. Prevalence of pathogenetic MC4R mutations in Italian children with early onset obesity, tall stature and familial history of obesity. BMC MEDICAL GENETICS 2009; 10:25. [PMID: 19284607 PMCID: PMC2664798 DOI: 10.1186/1471-2350-10-25] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Accepted: 03/12/2009] [Indexed: 12/04/2022]
Abstract
Background Melanocortin-4-receptor (MC4R) mutations represent the most frequent genetic cause of non-syndromic early onset obesity. Children carrying MC4R mutations seem to show a particular phenotype characterized by early onset, severe obesity and high stature. To verify whether MC4R mutations are associated with this particular phenotype in the Italian pediatric population, we decided to screen the MC4R gene in a group of obese children selected on the basis of their phenotype. Methods To perform this study, a multicentric approach was designed. Particularly, to be enrolled in the study subjects needed to meet the following criteria: Body mass index ≥ 3 deviation scores according to age and sex, familiar history of obesity (at least one parent obese), obesity onset before the 10 years old, height ≥ 2 deviation scores. The coding region of MC4R gene was screened in 240 obese children (mean age 8.3 ± 3.1, mean BMI 30.8 ± 5.4) and in 200 controls (mean age 8.1 ± 2.8; mean BMI 14.2 ± 2.5). Results Three mutations have been found in five obese children. The S127L (C380T), found in three unrelated children, had been described and functionally characterized previously. The Q307X (C919T) and the Y332H (T994C) mutations were found in two patients. Functional studies showed that only Q307X impaired protein function. Conclusion The low prevalence of MC4R mutations (1.6%) in this group of obese children selected according to the obesity degree, the tall stature and the family history of obesity was similar to the prevalence observed in previous screenings performed in obese adults and in not phenotypically selected obese children.
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Affiliation(s)
- Nicola Santoro
- Dipartimento di Pediatria F, Fede, Seconda Università degli Studi di Napoli, Napoli, Italy.
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12
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Donahoo WT, Hernandez TL, Costa JL, Jensen DR, Morris AM, Brennan MB, Hochgeschwender U, Eckel RH. Plasma alpha-melanocyte-stimulating hormone: sex differences and correlations with obesity. Metabolism 2009; 58:16-21. [PMID: 19059526 DOI: 10.1016/j.metabol.2008.07.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2007] [Accepted: 07/29/2008] [Indexed: 10/21/2022]
Abstract
Rodent experiments raise the possibility of a regulatory role of peripheral alpha-melanocyte-stimulating hormone (alpha-MSH) in obesity and metabolism, but human data on peripheral alpha-MSH levels remain fragmentary. Because of the possible relationship between alpha-MSH and obesity, we endeavored to test the hypothesis that higher levels of alpha-MSH in obese patients would correlate with leptin levels and with other markers of obesity. Sixty normal-weight to obese healthy men and women participated. Weight, measures of body composition, and diet diaries were obtained; fasting blood was analyzed for alpha-MSH, lipids, glucose, insulin, leptin, and adiponectin. To begin to understand the source of peripherally measured hormones, alpha-MSH was also measured in serum samples from 5 individuals with untreated Addison disease. Levels of alpha-MSH were higher in men vs women (10.1 +/- 4.3 vs 7.6 +/- 3.4 pmol/L, P = .019), and alpha-MSH levels were higher in patients with Addison disease vs controls (17.7 +/- 2.3 vs 8.7 +/- 0.52 pmol/L, P < .001). Measures of adiposity correlated with insulin and leptin in men and women, and with adiponectin in women. alpha-Melanocyte-stimulating hormone levels did not correlate significantly with any parameter of adiposity or diet composition. The elevated alpha-MSH levels in patients with untreated Addison disease suggest possible pituitary secretion of alpha-MSH to the periphery. The lack of correlation between peripheral alpha-MSH and parameters of adiposity suggests that endogenous plasma alpha-MSH levels are not a metric for body composition per se.
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Affiliation(s)
- William T Donahoo
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Denver, P.O. Box 6511, Aurora, CO 80045, USA
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Tao YX. Functional characterization of novel melanocortin-3 receptor mutations identified from obese subjects. Biochim Biophys Acta Mol Basis Dis 2007; 1772:1167-74. [DOI: 10.1016/j.bbadis.2007.09.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2007] [Revised: 08/27/2007] [Accepted: 09/07/2007] [Indexed: 10/22/2022]
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15
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Hart Sailors ML, Folsom AR, Ballantyne CM, Hoelscher DM, Jackson AS, Linda Kao WH, Pankow JS, Bray MS. Genetic variation and decreased risk for obesity in the Atherosclerosis Risk in Communities Study. Diabetes Obes Metab 2007; 9:548-57. [PMID: 17587397 DOI: 10.1111/j.1463-1326.2006.00637.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
AIM To investigate the effects of variation in the leptin [LEP (19A>G)] and melanocortin-4 receptor [MC4R (V103I)] genes on obesity-related traits in 13 405 African-American (AA) and white participants from the Atherosclerosis Risk in Communities (ARIC) Study. METHODS We tested the association between the single-locus and multilocus genotypes and obesity-related measures [body mass index (BMI), body weight (BW), waist-hip ratio, waist circumference and leptin levels], adjusted for age, physical activity level, smoking status, diabetic status, prevalence of coronary heart disease, hypertension, stroke or transient ischaemic attack. RESULTS AA and white female carriers of the MC4R I103 allele exhibited significantly lower BW than non-carriers of this allele (p < 0.05 and p < 0.01 respectively). AA female carriers of both the LEP A19 allele and the MC4R I103 allele were 63% [odds ratio (OR) = 0.37, 95% confidence interval (CI) (0.18-0.78)] less likely to be obese, and white female carriers of the same two alleles were 46% [OR = 0.54, 95% CI (0.32-0.91)] less likely to be obese, than non-carriers of the variant alleles. Female carriers of both the LEP A19 and MC4R I103 alleles had significantly lower BW (p < 0.05), BMI (p < 0.05) and plasma leptin (p < 0.01) than the non-carriers of both the alleles. Carriers of the two variant alleles had lower BMI over the 9-year course of the ARIC study and significantly lower weight gain from age 25 years. No significant joint effect of these two variants was observed in males. CONCLUSION These results suggest that variation within the LEP and MC4R genes is associated with reduced risk for obesity in females.
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Affiliation(s)
- M L Hart Sailors
- Department of Pediatrics, Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX 77030, USA
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16
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Yosipovitch G, DeVore A, Dawn A. Obesity and the skin: Skin physiology and skin manifestations of obesity. J Am Acad Dermatol 2007; 56:901-16; quiz 917-20. [PMID: 17504714 DOI: 10.1016/j.jaad.2006.12.004] [Citation(s) in RCA: 266] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2005] [Revised: 10/26/2006] [Accepted: 12/05/2006] [Indexed: 11/28/2022]
Abstract
UNLABELLED Obesity is widely recognized as an epidemic in the Western world; however, the impact of obesity on the skin has received minimal attention. The purpose of this article is to highlight the association between obesity and dermatologic conditions. We review the impact of obesity on the skin, including skin physiology, skin manifestations of obesity, and dermatologic diseases aggravated by obesity. Obesity is responsible for changes in skin barrier function, sebaceous glands and sebum production, sweat glands, lymphatics, collagen structure and function, wound healing, microcirculation and macrocirculation, and subcutaneous fat. Moreover, obesity is implicated in a wide spectrum of dermatologic diseases, including acanthosis nigricans, acrochordons, keratosis pilaris, hyperandrogenism and hirsutism, striae distensae, adiposis dolorosa, and fat redistribution, lymphedema, chronic venous insufficiency, plantar hyperkeratosis, cellulitis, skin infections, hidradenitis suppurativa, psoriasis, insulin resistance syndrome, and tophaceous gout. We review the clinical features, evidence for association with obesity, and management of these various dermatoses and highlight the profound impact of obesity in clinical dermatology. LEARNING OBJECTIVE After completing this learning activity, participants should be aware of obesity-associated changes in skin physiology, skin manifestations of obesity, and dermatologic diseases aggravated by obesity, and be able to formulate a pathophysiology-based treatment strategy for obesity-associated dermatoses.
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Affiliation(s)
- Gil Yosipovitch
- Departments of Dermatology, Regenerative Medicine, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
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Abstract
We present the knowledge acquired in the field of the genetics of human obesity. The molecular approach proved to be powerful to define new syndromes associated to obesity. The pivotal role of leptin and melanocortin pathways were recognized but in rare obesity cases. In the commoner form of obesities, a multitude of polymorphisms located in genes and candidate regions participate in an individual susceptibility to weight gain in a permissive environment. The effects are often uncertain and the results not always confirmed. It is now necessary to integrate data of various origins (environment, genotype, expression) to clarify the domain.
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Affiliation(s)
- Karine Clément
- INSERM, U755 & IFR58, université Pierre-et-Marie Curie (Paris-6), 75004 Paris, France.
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MacKenzie RG. Obesity-associated mutations in the human melanocortin-4 receptor gene. Peptides 2006; 27:395-403. [PMID: 16274851 DOI: 10.1016/j.peptides.2005.03.064] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2004] [Accepted: 03/07/2005] [Indexed: 10/25/2022]
Abstract
Mutations in the human melanocortin-4 receptor (MC4R) gene have been associated with severe obesity. Many of the mutations result in partial or complete loss-of-function based on the nature of the mutation or the function of mutated receptors when tested in heterologous expression systems. This review discusses the role of MC4R in the central regulation of body weight, the pathogenic mechanisms of the mutations, and the validity of MC4R as an anti-obesity drug target.
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Affiliation(s)
- Robert G MacKenzie
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, 3228 Scott Hall, 540 E. Canfield, Detroit, MI 48201, USA.
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Santoro N, Rankinen T, Pérusse L, Loos RJF, Bouchard C. MC4R marker associated with stature in children and young adults: a longitudinal study. J Pediatr Endocrinol Metab 2005; 18:859-63. [PMID: 16279363 DOI: 10.1515/jpem.2005.18.9.859] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We investigated the associations between a polymorphism in the melanocortin 4 receptor (MC4R) gene and changes in body size and composition from childhood to adulthood in the Québec Family Study. Ninety-one subjects (43 males) less than 18 years of age (mean age 13.5 +/- 2.4 years; range 8.4-17.8 years) at baseline were re-measured 11.2 years later on average. The anthropometric variables analyzed were height, weight, body mass index, percent body fat, sum of skinfolds, fat mass index, and fat free mass index (FFMI). All variables were adjusted for age and sex. The subjects were genotyped for the MC4R C-2745T polymorphism. Forty-five subjects were homozygotes for the common allele (C/C), 36 were heterozygotes (C/T) and 10 were homozygotes for the rare allele (T/T). The rare allele was associated with increased height at baseline as well as at the follow-up visit. Although FFMI tended to increase more in subjects carrying the rare allele, no significant differences were found for the changes over time for the other phenotypes. These results suggest that DNA sequence variation in the MC4R locus may contribute to the gain in body height from childhood to adulthood.
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Affiliation(s)
- Nicola Santoro
- Pennington Biomedical Research Center, Human Genomics Laboratory, Baton Rouge, LA 70808-4124, USA
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20
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Daniel PB, Fernando C, Wu CSJ, Marnane R, Broadhurst R, Mountjoy KG. 1 kb of 5' flanking sequence from mouse MC4R gene is sufficient for tissue specific expression in a transgenic mouse. Mol Cell Endocrinol 2005; 239:63-71. [PMID: 15950372 DOI: 10.1016/j.mce.2005.03.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2004] [Revised: 03/10/2005] [Accepted: 03/16/2005] [Indexed: 10/25/2022]
Abstract
The melanocortin 4 receptor (MC4R) plays a critical role in the regulation of energy homeostasis, and the MC4R knockout mouse and humans with MC4R defective mutations in only one allele indicate that there is a gene dosage effect. Alterations in gene expression levels for MC4R could, therefore, have significant effects on energy homeostasis. To begin to develop a mouse model for studies on MC4R promoter in situ we used approximately 1 kb mouse MC4R promoter together with 426 bp MC4R 5' UTR, previously shown to support basal expression of reporter gene transcription in cell lines with endogenous MC4R mRNA, and fused this DNA to a nuclear localized LacZ reporter gene. The construct was injected into pronuclei from FVB mice. Five transgenic lines were identified as carrying autosomal transgene insertions; three of these had significant beta-galactosidase staining in brain and in a few cells in the heart but not in kidney, liver, lung, gonadal fat or testis. The pattern of transgene expression in the brain differed markedly for the three lines, and in one of these lines was remarkably similar to endogenous MC4R mRNA expression observed using in situ hybridisation. In conclusion, approximately 1 kb mouse MC4R promoter is sufficient to direct gene expression to the brain including regions that express endogenous MC4R mRNA.
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Affiliation(s)
- Philip B Daniel
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1, New Zealand
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21
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Tao YX, Segaloff DL. Functional characterization of melanocortin-3 receptor variants identify a loss-of-function mutation involving an amino acid critical for G protein-coupled receptor activation. J Clin Endocrinol Metab 2004; 89:3936-42. [PMID: 15292330 DOI: 10.1210/jc.2004-0367] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Although melanocortin-4 receptor mutations are the cause of the most common monogenic form of obesity, the involvement of the melanocortin-3 receptor (MC3R) in the pathogenesis of obesity is unknown. Earlier studies failed to identify any mutations in obese patients except for the identification of two variants (K6T and I81V) that likely represent polymorphisms. However, a potential mutation (I183N) was recently reported from patients having high-fat contents. We report here the functional characterization of these variants. We show that K6T and I81V have ligand binding and signaling properties similar to wild-type (wt) MC3R, indicating that they are indeed polymorphisms. However, the other variant, I183N, completely lacks signaling in response to agonist stimulation, although it binds ligand with normal affinity and with only slightly decreased capacity. Coexpression of the wt and I183N MC3Rs showed that I183N does not exert dominant-negative activity on wt MC3R. These results provide supporting evidence for the hypothesis proposed in the original case report that MC3R mutation might be a genetic factor that confers susceptibility to obesity, likely due to haploinsufficiency. Further mutations at I183 revealed a discrete requirement for I183 in agonist-induced MC3R activation. The corresponding residue is also important for agonist-induced human melanocortin-4 receptor and lutropin receptor activation. In summary, we identify a residue that is critical for activation of G protein-coupled receptors.
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MESH Headings
- Asparagine
- Cell Line
- Codon
- Gene Expression Regulation
- Genetic Variation
- Humans
- Isoleucine
- Lysine
- Mutation
- Receptor, Melanocortin, Type 3/agonists
- Receptor, Melanocortin, Type 3/genetics
- Receptor, Melanocortin, Type 3/metabolism
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Receptors, LH/agonists
- Receptors, LH/genetics
- Receptors, LH/metabolism
- Threonine
- Valine
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Affiliation(s)
- Ya-Xiong Tao
- Department of Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, USA.
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Bastarrachea RA, Cole SA, Comuzzie AG. Genómica de la regulación del peso corporal: mecanismos moleculares que predisponen a la obesidad. Med Clin (Barc) 2004; 123:104-17. [PMID: 15225477 DOI: 10.1016/s0025-7753(04)74427-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Obesity has become a worldwide public health problem which affects millions of people. Substantial progress has been made in elucidating the pathogenesis of energy homeostasis over the past few years. The fact that obesity is under strong genetic control has been well established. Twin, adoption and family studies have shown that genetic factors play a significant role in the pathogenesis of obesity. Human monogenic obesity is rare in large populations. The most common form of obesity is considered to be a polygenic disorder. New treatments are currently required for this common metabolic disease and type 2 diabetes. The identification of physiological and biochemical factors that underlie the metabolic disturbances observed in obesity is a key step in developing better therapeutic outcomes. The discovery of new genes and pathways involved in the pathogenesis of such a disease is critical to this process. However, identification of genes that contribute to the risk of developing the disease represents a significant challenge since obesity is a complex disease with many genetic and environmental causes. A number of diverse approaches have been used to discover and validate potential new genes for obesity. To date, DNA-based approaches using candidate genes and genome-wide linkage analysis have not had a great success in identifying genomic regions or genes involved in the development of these diseases. Recent advances in the ability to evaluate linkage analysis data from large family pedigrees (using variance components-based linkage analysis) show great promise in robustly identifying genomic regions associated with the development of obesity. Studying rare mutations in humans and animal models has provided fundamental insight into a complex physiological process, and has complemented population-based studies that seek to reveal primary causes. Remarkable progress has been made in both fronts and the pace of advance is likely to accelerate as functional genomics and the human genome project expand and mature. Approaches based on Mendelian and quantitative genetics may well converge, and ultimately lead to more rational and selective therapies.
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Affiliation(s)
- Raúl A Bastarrachea
- Department of Genetics, Auxology and Metabolism Working Group, Southwest Foundation for Biomedical Research, San Antonio, Texas, USA.
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23
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Haqq AM, René P, Kishi T, Khong K, Lee CE, Liu H, Friedman JM, Elmquist JK, Cone RD. Characterization of a novel binding partner of the melanocortin-4 receptor: attractin-like protein. Biochem J 2004; 376:595-605. [PMID: 14531729 PMCID: PMC1223823 DOI: 10.1042/bj20031241] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2003] [Revised: 09/15/2003] [Accepted: 10/07/2003] [Indexed: 11/17/2022]
Abstract
The gene dosage effect of the MC4-R (melanocortin 4 receptor) on obesity suggests that regulation of MC4-R expression and function is critically important to the central control of energy homoeostasis. In order to identify putative MC4-R regulatory proteins, we performed a yeast two-hybrid screen of a mouse brain cDNA library using the mouse MC4-R intracellular tail (residues 303-332) as bait. We report here on one positive clone that shares 63% amino acid identity with the C-terminal part of the mouse attractin gene product, a single-transmembrane-domain protein characterized as being required for agouti signalling through the melanocortin 1 receptor. We confirmed a direct interaction between this ALP (attractin-like protein) and the C-terminus of the mouse MC4-R by glutathione S-transferase pulldown experiments, and mapped the regions involved in this interaction using N- and C-terminal truncation constructs; residues 303-313 in MC4-R and residues 1280-1317 in ALP are required for binding. ALP is highly expressed in brain, but also in heart, lung, kidney and liver. Furthermore, co-localization analyses in mice showed co-expression of ALP in cells expressing MC4-R in a number of regions known to be important in the regulation of energy homoeostasis by melanocortins, such as the paraventricular nucleus of hypothalamus and the dorsal motor nucleus of the vagus.
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Affiliation(s)
- Andrea M Haqq
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
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24
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Donohoue PA, Tao YX, Collins M, Yeo GSH, O'Rahilly S, Segaloff DL. Deletion of codons 88-92 of the melanocortin-4 receptor gene: a novel deleterious mutation in an obese female. J Clin Endocrinol Metab 2003; 88:5841-5. [PMID: 14671178 DOI: 10.1210/jc.2003-030903] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Genetic and pharmacological studies have shown that the melanocortin-4 receptor (MC4R) is an important regulator of food intake and energy homeostasis. Consistent with these studies, several mutations of the MC4R gene have been identified as being associated with early-onset severe obesity. We report here the first in-frame deletion mutation of the MC4R gene (delta88-92) in an obese female patient with onset of obesity at less than 5 yr of age. Functional analysis revealed that the mutant receptor is expressed well on the cell surface but completely devoid of ligand binding and cAMP generation in response to agonist stimulation. We conclude that this novel mutation is the cause of obesity of this patient.
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Affiliation(s)
- Patricia A Donohoue
- Department of Pediatrics, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, USA.
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26
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Abstract
PURPOSE OF REVIEW The models currently proposed for the genetic architecture of obesity are critically reviewed in the light of recent developments in the search for genetic causes of this condition. RECENT FINDINGS As for many other 'complex' diseases, most of the genetic variants predisposing to human obesity have not yet been identified. To date, investigation of the genetic contribution to obesity has been conducted according to two main hypotheses. The common disease/common variant hypothesis proposes that the genetic architecture of complex diseases (including obesity) is likely to consist of a limited number of alleles, each conferring a small increase in risk to the individual. Alternatively, it has also been proposed that complex diseases such as obesity may instead result from the effects of a large number of rare variants, with substantial allelic heterogeneity at disease-causing loci. These two hypotheses have shaped strategies for the identification of disease genes, including the use of linkage analysis, association studies and the systematic sequencing of candidate genes. Linkage studies have recently been very successful in identifying new genes in which mutations cause rare monogenic syndromes of obesity. In common obesity, numerous linkage and association studies have suggested that an increasing number of genetic loci could be involved. Overall, however, these studies have failed to identify the causal genetic variants. In contrast, the direct sequencing of well-chosen candidate genes has led to the identification of numerous rare alleles causing both syndromic and common obesity, which are less severe forms of the condition in humans. SUMMARY The genetic architecture of obesity is still a matter of debate. The previously accepted hypothesis of a small number of common variants has been undermined by the low reproducibility of association studies and inconsistencies among genome scans for obesity. While high-throughput association mapping of candidate regions holds some promise for the identification of common susceptibility alleles, it must also be considered that the genetic predisposition to obesity may instead result from multiple rare variants in a large number of genes.
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Affiliation(s)
- Michael M Swarbrick
- Diabetes Center, University of California, San Francisco, California 94143-0540, USA
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Abstract
Obesity has become a leading public health concern. Over 1 billion people are now overweight or obese, and the prevalence of these conditions is rising rapidly. Remarkable new insights into the mechanisms that control body weight are providing an increasingly detailed framework for a better understanding of obesity pathogenesis. Key peripheral signals, such as leptin, insulin, and ghrelin, have been linked to hypothalamic neuropeptide systems, and the anatomic and functional networks that integrate these systems have begun to be elucidated. This article highlights some of these recent findings and their implications for the future of obesity treatment.
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Affiliation(s)
- David E Cummings
- Department of Medicine, VA Puget Sound Health Care System and Harborview Medical Center, University of Washington, Seattle, Washington 98195, USA.
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VanLeeuwen D, Steffey ME, Donahue C, Ho G, MacKenzie RG. Cell surface expression of the melanocortin-4 receptor is dependent on a C-terminal di-isoleucine sequence at codons 316/317. J Biol Chem 2003; 278:15935-40. [PMID: 12594226 DOI: 10.1074/jbc.m211546200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Loss-of-function mutations in the human melanocortin-4 receptor (MC4R) are associated with obesity. Previous work has implicated a C-terminal di-isoleucine motif at residues 316/317 in MC4R cell surface targeting. It was therefore of interest to examine function and cell surface expression of an MC4R mutation found in an obese proband in which one of these isoleucines was substituted by threonine (I317T). Single mutant (I316T or I317T) and double mutant (I316T,I317T) forms of MC4R were constructed by oligonucleotide-directed mutagenesis and tested for function and cell surface expression in transfected cells. Function was assessed using assays for agonist, [Nle(4)-d-Phe(7)]alpha-melanocyte-stimulating hormone (NDP-alpha-MSH) or forskolin-stimulated cAMP accumulation. Cell surface expression was determined by whole-cell binding of [(125)I]NDP-alpha-MSH, fluorescence immunocytochemistry and fluorescence-activated cell sorting. Maximal cAMP generation of the single mutants was reduced by 40% of wild-type receptor; the double mutant further reduced function to 40% of control, effects that were mirrored by decreases in cell-surface expression. Quantitative RT-PCR showed that, relative to wild-type receptor, transcript levels for the mutated receptors were not reduced. The results further implicate the C-terminal di-isoleucines in cell surface expression of MC4R and suggest that mutations of residues 316 or 317 would predict MC4R hypofunction.
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Clement K, Boutin P, Froguel P. Genetics of obesity. AMERICAN JOURNAL OF PHARMACOGENOMICS : GENOMICS-RELATED RESEARCH IN DRUG DEVELOPMENT AND CLINICAL PRACTICE 2003; 2:177-87. [PMID: 12383024 DOI: 10.2165/00129785-200202030-00003] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Obesity is a typical common multifactorial disease in which environmental and genetic factors interact. In rare cases of severe obesity with childhood onset, a single gene has a major effect in determining the occurrence of obesity, with the environment having only a permissive role in the severity of the phenotype. Exceptional mutations of the leptin gene and its receptor, pro-opiomelanocortine (POMC), prohormone convertase 1 (PC1) and more frequently, mutations in the melanocortin receptor 4 (1 to 4% of very obese cases) have been described. All these obesity genes encode proteins that are strongly connected as part of the same loop of the regulation of food intake. They all involve the leptin axis and one of its hypothalamic targets; the melanocortin pathway. Pathways of bodyweight regulation involved in monogenic forms of obesity might represent targets for future drug development. Successful leptin protein replacement in a leptin-deficient child has contributed to the validation of the usefulness of gene screening in humans. However, the individual variability in response to leptin treatment might be related to genetic variability. The efficiency of leptin itself or of small-molecule agonists of the leptin receptor should be studied in relation with genetic variations in the leptin gene promoter. The most common forms of obesity are polygenic. Two general approaches have been used to date in the search for genes underlying common polygenic obesity in humans. The first approach focuses on selected genes having some plausible role in obesity on the basis of their known or presumed biological role. This approach yielded putative susceptibility genes with only small or uncertain effects. The second approach attempts to map genes purely by position and requires no presumptions on the function of genes. Genome-wide scans identify chromosomal regions showing linkage with obesity in large collections of nuclear families. Genome-wide scans in different ethnic populations have localized major obesity loci on chromosomes 2, 5, 10, 11 and 20. Susceptibility gene(s) for obesity may be positionally cloned in the intervals of linkage. The candidate gene and positional cloning of major obesity-linked regions approaches are discussed in this paper.
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Affiliation(s)
- Karine Clement
- CNRS-Institute of Biology of Lille, Pasteur Institute of Lille, 1 rue Calmette BP245, Lille 59016, France
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Marti A, Corbalán MS, Forga L, Martinez JA, Hinney A, Hebebrand J. A novel nonsense mutation in the melanocortin-4 receptor associated with obesity in a Spanish population. Int J Obes (Lond) 2003; 27:385-8. [PMID: 12629567 DOI: 10.1038/sj.ijo.0802244] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND In recent years, several groups have reported dominant inheritance of obesity conferred by missense, nonsense and frameshift mutations in the melanocortin 4 receptor gene (MC4R). Hence, MC4R is involved in the most common monogenic form of human obesity described so far. OBJECTIVES In this context, we screened a Spanish population, composed of obese subjects and normal weight controls, for mutations in the MC4-R by single-strand conformational polymorphism (SSCP). SUBJECTS AND METHODS Overall 313 individuals, 159 obese subjects (body mass index: BMI: 37.6 kg/m(2), 95% CI: 36.7-38.5 kg/m(2)) and 154 normal weight control subjects (BMI: 22.3 kg/m(2), 95% CI: 22.0-22.6 kg/m(2)) were screened for MC4-R mutations. RESULTS We detected a novel nonsense mutation at codon 16 of the MC4-R in an obese female (BMI: 30.0 kg/m(2)) and a previously described missense mutation (Val-253-Ile) located within the sixth trans-membrane domain of the MC4-R in a normal weight individual (BMI: 19.0 kg/m(2)). The polymorphism Val-103-Ile was detected in one obese individual, while four subjects (two cases and two controls) with the polymorphism Ile-251-Leu were found. CONCLUSIONS We have identified a novel nonsense mutation (Trp-16-Stop) that, based on previously described frameshift and nonsense mutations, most likely results in dominantly inherited obesity. Within this Spanish population, the frequency of the Ile-251-Leu polymorphism of the MC4R was similar in obese and control subjects (about 1.3%), while the polymorphism Val-103-Ile was only detected in an obese individual (0.6%).
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Affiliation(s)
- A Marti
- Department of Physiology and Nutrition, University of Navarra, Pamplona, Spain.
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Hebebrand J, Fichter M, Gerber G, Görg T, Hermann H, Geller F, Schäfer H, Remschmidt H, Hinney A. Genetic predisposition to obesity in bulimia nervosa: a mutation screen of the melanocortin-4 receptor gene. Mol Psychiatry 2003; 7:647-51. [PMID: 12140789 DOI: 10.1038/sj.mp.4001053] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2001] [Revised: 11/04/2001] [Accepted: 11/23/2001] [Indexed: 11/08/2022]
Abstract
Obesity has been identified as a risk factor for the development of bulimia nervosa (BN). Accordingly, we hypothesize that genotypes predisposing to obesity can be detected in patients with this eating disorder. In order to investigate this hypothesis we screened the melanocortin-4 receptor gene (MC4R) for mutations using single strand conformation analysis in 81 female inpatients treated for BN. A single patient with both extreme obesity and BN had a haplo-insufficiency mutation in the MC4R. Comparison of current and maximal body mass index (BMI) of all patients with cross-sectionally obtained BMI in the general population revealed an age appropriate distribution for current BMI and a substantially increased frequency for overweight at time of maximal BMI. Our findings suggest that overweight is a risk factor for BN in clinically ascertained patients. For the first time a genotype predisposing to obesity has been detected in an extremely obese patient with BN.
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Affiliation(s)
- J Hebebrand
- Clinical Research Group, Department of Child and Adolescent Psychiatry of the Philipps University Marburg, Germany.
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Miraglia Del Giudice E, Cirillo G, Nigro V, Santoro N, D'Urso L, Raimondo P, Cozzolino D, Scafato D, Perrone L. Low frequency of melanocortin-4 receptor (MC4R) mutations in a Mediterranean population with early-onset obesity. Int J Obes (Lond) 2002; 26:647-51. [PMID: 12032748 DOI: 10.1038/sj.ijo.0801983] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2001] [Revised: 10/26/2001] [Accepted: 12/18/2001] [Indexed: 12/21/2022]
Abstract
BACKGROUND Melanocortin-4 receptor (MC4R) mutations have been reported as the most common single genetic cause of obesity in some populations and it has been suggested that they may be responsible for more than 4% of early-onset obesity. OBJECTIVES To verify the presence of mutations of the MC4R coding region in children from southern Italy with early-onset obesity. SUBJECTS AND METHODS Two-hundred and eight unrelated obese children and adolescents were included in the study. The average age at obesity onset was 4.5+/-2.6 y. MC4R coding region was screened using both single-strand conformation polymorphism (SSCP) analysis and denaturing high-performance liquid chromatography (DHPLC). Automatic sequencing of PCR products of all individuals that showed an aberrant SSCP and/or DHPLC pattern was performed. RESULTS One novel missense mutation and one previously described polymorphism (Vall03Ile) were identified. The missense mutation C142T, resulting in the substitution of proline with serine at codon 48, within the first MC4R transmembrane domain, was detected at the heterozygous state in a 15-y-old obese girl (body mass index (BMI)=35 kg/m(2)) who has been obese since she was 8 y old. The mutation co-segregated with the obesity phenotype for over three generations and was not found in the control population. CONCLUSIONS Our data show MC4R obesity causing mutations in less than 0.5% of the patients (ie 1 out of 208 patients) and therefore indicate a low prevalence of MC4R variants in the obese population from southern Italy. The specific genetic background of the Mediterranean population could make it difficult for MC4R mutations to produce an essentially polygenic trait such as common obesity, at least during childhood.
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Abstract
Identifying the role of the melanocortin system in regulating energy homeostasis has relied on both genetic and pharmacological studies. The key findings included 1) that the coat color phenotype in the lethal yellow (A(Y)/a) mouse is due to antagonism of the melanocortin-1 receptor (MC1R) by the agouti gene product; 2) the MC3R and MC4R are expressed in CNS centers involved in energy homeostasis, and 3) the combined results of pharmacological studies showing that agouti is an antagonist of the MC4R and transgenic studies showing that inhibition or loss of the MC4R recapitulate the lethal yellow phenotype. Pro-opiomelanocortin (POMC), MC3R, and MC4R knockouts are obese and are now being used to further analyze melanocortin receptor function. The obesity phenotype observed in the MC3R and MC4R knockouts (KO) differ markedly. MC4RKO mice are hyperphagic, do not regulate pathways that increase energy expenditure (diet-induced thermogenesis) and physical activity in response to hyperphagia, and can develop type 2 diabetes. In contrast, MC3R deficient mice are not hyperphagic, have a normal metabolic response to increased energy consumption, and do not develop diabetes. The mechanism underlying the increased adiposity in the MC3R knockout remains unclear, but might be related to changes in nutrient partitioning or physical activity.
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Affiliation(s)
- A A Butler
- Neuropeptides Laboratory, Pennington Biomedical Research Center, Lousiana State university, Baton Rouge, LA70808, USA.
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Froguel P, Boutin P. Genetics of pathways regulating body weight in the development of obesity in humans. Exp Biol Med (Maywood) 2001; 226:991-6. [PMID: 11743134 DOI: 10.1177/153537020122601105] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Although rapid globalization of the Westernized way of life is responsible for the large rise in the number of obesity cases (about 1 billion individuals are now overweight or frankly obese), obesity is a typical common multifactorial disease in that environmental and genetic factors interact, resulting in a disease state. There is strong evidence for a genetic component to human obesity: e.g., the familial clustering (the relative risk among siblings being 3-7) and the high concordance of body composition in monozygotic twins. However, the role of genetic factors in many human obesities (referred to as "common obesity" in this review) is complex, being determined by interaction of several genes (polygenic), each of which may have relatively small effects (i.e., they are "susceptibility" genes and work in combination with each other as well as with environmental factors such as nutrients, physical activity, and smoking).
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Affiliation(s)
- P Froguel
- Centre National de la Recherche Scientifique, Institute of Biology of Lille, Pasteur Institute of Lille, France.
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Abstract
Obesity is a multifactorial condition. Environmental risk factors related to a sedentary life-style and unlimited access to food apply constant pressure in subjects with a genetic predisposition to gain weight. The fact that genetic defects can result in human obesity has been unequivocally established over the past 3 years with the identification of the genetic defects responsible for different monogenic forms of human obesity: the leptin, leptin receptor, pro-opiomelanocortin, pro-hormone convertase-1 and melanocortin-4 receptor genes. The common forms of obesity are, however, polygenic. The examination of specific genes for involvement in the susceptibility to common obesity has not yet yielded convincing results. Approaches involving the candidate genes and the positional cloning of major obesity-linked regions (state-of-the-art future prospects) will be discussed.
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Affiliation(s)
- P Boutin
- CNRS-Institute of Biology of Lille, Pasteur Institute of Lille, France
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Abstract
The increasing prevalence of obesity worldwide has prompted the World Health Organization (WHO) to classify it as a global epidemic. Around the globe, more than a half billion people are overweight, and the chronic disease of obesity represents a major threat to health care systems in developed and developing countries. The major health hazards associated with obesity are the risks of developing diabetes, cardiovascular disease, stroke, osteoarthritis and some forms of cancer. In this paper, we review the prevalence of obesity and its cost to health care systems and present the relative contribution of environmental conditions and genetic makeup to the development of obesity in people. We also discuss the concept of "essential" obesity in an "obesigenic" environment. Though weight gain results from a sustained imbalance between energy intake and energy expenditure, it is only recently that studies have identified important new mechanisms involved in the regulation of body weight. The etiology of the disease is presented as a feedback model in which afferent signals inform the central controllers in the brain as to the state of the external and internal environment and elicit responses related to the regulation of food intake and energy metabolism. Pharmaceutical agents may intervene at different levels of this feedback model, i.e., reinforce the afferent signals from the periphery, target the central pathways involved in the regulation of food intake and energy expenditure, and increase peripheral energy expenditure and fat oxidation directly. Since obesity results from genetic predisposition, combined with the proactive environmental situation, we discuss new potential targets for generation of drugs that may assist people in gaining control over appetite as well as increasing total energy expenditure and fat oxidation.
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Affiliation(s)
- E Ravussin
- Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, LA 70808-4124, USA.
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MESH Headings
- Adipose Tissue/metabolism
- Alleles
- Animals
- Body Weight
- Feeding Behavior
- Humans
- Leptin/metabolism
- Leptin/physiology
- Ligands
- Mice
- Mice, Knockout
- Models, Biological
- Obesity/genetics
- Phenotype
- Protein Isoforms
- Receptor, Melanocortin, Type 3
- Receptor, Melanocortin, Type 4
- Receptors, Corticotropin/chemistry
- Receptors, Corticotropin/genetics
- Receptors, Corticotropin/physiology
- Receptors, Peptide/chemistry
- Receptors, Peptide/genetics
- Receptors, Peptide/physiology
- Signal Transduction
- alpha-MSH/metabolism
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