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Liu T, Ji RL, Tao YX. Naturally occurring mutations in G protein-coupled receptors associated with obesity and type 2 diabetes mellitus. Pharmacol Ther 2021; 234:108044. [PMID: 34822948 DOI: 10.1016/j.pharmthera.2021.108044] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 11/15/2021] [Accepted: 11/15/2021] [Indexed: 12/12/2022]
Abstract
G protein-coupled receptors (GPCRs) are the largest family of membrane receptors involved in the regulation of almost all known physiological processes. Dysfunctions of GPCR-mediated signaling have been shown to cause various diseases. The prevalence of obesity and type 2 diabetes mellitus (T2DM), two strongly associated disorders, is increasing worldwide, with tremendous economical and health burden. New safer and more efficacious drugs are required for successful weight reduction and T2DM treatment. Multiple GPCRs are involved in the regulation of energy and glucose homeostasis. Mutations in these GPCRs contribute to the development and progression of obesity and T2DM. Therefore, these receptors can be therapeutic targets for obesity and T2DM. Indeed some of these receptors, such as melanocortin-4 receptor and glucagon-like peptide 1 receptor, have provided important new drugs for treating obesity and T2DM. This review will focus on the naturally occurring mutations of several GPCRs associated with obesity and T2DM, especially incorporating recent large genomic data and insights from structure-function studies, providing leads for future investigations.
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Affiliation(s)
- Ting Liu
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, AL 36849, United States
| | - Ren-Lei Ji
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, AL 36849, United States
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, AL 36849, United States.
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2
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Heyder N, Kleinau G, Szczepek M, Kwiatkowski D, Speck D, Soletto L, Cerdá-Reverter JM, Krude H, Kühnen P, Biebermann H, Scheerer P. Signal Transduction and Pathogenic Modifications at the Melanocortin-4 Receptor: A Structural Perspective. Front Endocrinol (Lausanne) 2019; 10:515. [PMID: 31417496 PMCID: PMC6685040 DOI: 10.3389/fendo.2019.00515] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 07/15/2019] [Indexed: 12/19/2022] Open
Abstract
The melanocortin-4 receptor (MC4R) can be endogenously activated by binding of melanocyte-stimulating hormones (MSH), which mediates anorexigenic effects. In contrast, the agouti-related peptide (AgRP) acts as an endogenous inverse agonist and suppresses ligand-independent basal signaling activity (orexigenic effects). Binding of ligands to MC4R leads to the activation of different G-protein subtypes or arrestin and concomitant signaling pathways. This receptor is a key protein in the hypothalamic regulation of food intake and energy expenditure and naturally-occurring inactivating MC4R variants are the most frequent cause of monogenic obesity. In general, obesity is a growing problem on a global scale and is of social, medical, and economic relevance. A significant goal is to develop optimized pharmacological tools targeting MC4R without adverse effects. To date, this has not been achieved because of inter alia non-selective ligands across the five functionally different MCR subtypes (MC1-5R). This motivates further investigation of (i) the three-dimensional MC4R structure, (ii) binding mechanisms of various ligands, and (iii) the molecular transfer process of signal transduction, with the aim of understanding how structural features are linked with functional-physiological aspects. Unfortunately, experimentally elucidated structural information is not yet available for the MC receptors, a group of class A G-protein coupled receptors (GPCRs). We, therefore, generated MC4R homology models and complexes with interacting partners to describe approximate structural properties associated with signaling mechanisms. In addition, molecular insights from pathogenic mutations were incorporated to discriminate more precisely their individual malfunction of the signal transfer mechanism.
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Affiliation(s)
- Nicolas Heyder
- Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Gunnar Kleinau
- Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- *Correspondence: Gunnar Kleinau
| | - Michal Szczepek
- Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Dennis Kwiatkowski
- Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - David Speck
- Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Lucia Soletto
- Departamento de Fisiología de Peces y Biotecnología, Consejo Superior de Investigaciones Científicas, Instituto de Acuicultura Torre de la Sal, Ribera de Cabanes, Spain
| | - José Miguel Cerdá-Reverter
- Departamento de Fisiología de Peces y Biotecnología, Consejo Superior de Investigaciones Científicas, Instituto de Acuicultura Torre de la Sal, Ribera de Cabanes, Spain
| | - Heiko Krude
- Institute of Experimental Pediatric Endocrinology, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Peter Kühnen
- Institute of Experimental Pediatric Endocrinology, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Heike Biebermann
- Institute of Experimental Pediatric Endocrinology, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Patrick Scheerer
- Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Patrick Scheerer
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3
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Herrfurth N, Volckmar AL, Peters T, Kleinau G, Müller A, Cetindag C, Schonnop L, Föcker M, Dempfle A, Wudy SA, Grant SFA, Reinehr T, Cousminer DL, Hebebrand J, Biebermann H, Hinney A. Relevance of polymorphisms in MC4R and BDNF in short normal stature. BMC Pediatr 2018; 18:278. [PMID: 30134862 PMCID: PMC6106737 DOI: 10.1186/s12887-018-1245-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 08/06/2018] [Indexed: 12/13/2022] Open
Abstract
Background Variation in genes of the leptinergic-melanocortinergic system influence both body weight and height. Because short normal stature (SNS) is characterized by reduced body height, delayed maturation and leanness, allelic variation of genes in this pathway are hypothesized to affect this common condition. Methods We analyzed the coding regions of LEP, MC4R, MRAP2 and BDNF in 185 children with SNS (height < 5th percentile) to search for non-synonymous and frameshift variants. For association studies (two-sided χ2-tests) population-based data sets (ExAC, EVS and KORA) were used. Cyclic AMP accumulation, cell surface expression, central expression and MAP kinase activation were assayed in vitro to determine the functional implications of identified variants. Results We detected eleven variants predicted to be protein-altering, four in MC4R, four in BDNF, and three in MRAP2. No variants were found in LEP. In vitro analysis implied reduced function for the MC4R variant p.Met215Ile. Loss-of-function is contrary to expectations based on obesity studies, and thus does not support that this variant is relevant for SNS. The minor SNP alleles at MC4R p.Val103Ile and BDNF p.Val66Met were nominally associated with SNS. Conclusion Taken together, although genes of the leptinergic-melanocortinergic system are important for normal growth, our data do not support the involvement of rare mutations in LEP, MC4R, MRAP2 or BDNF in short normal stature. Electronic supplementary material The online version of this article (10.1186/s12887-018-1245-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Nikolas Herrfurth
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Anna-Lena Volckmar
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Triinu Peters
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Present Address: Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Anne Müller
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Cigdem Cetindag
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Laura Schonnop
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Manuel Föcker
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Astrid Dempfle
- Institute of Medical Informatics and Statistics, Christian-Albrechts University Kiel, Kiel, Germany
| | - Stefan A Wudy
- Division of Pediatric Endocrinology and Diabetology, Center of Child and Adolescent Medicine, Giessen, Germany
| | - Struan F A Grant
- Divisions of Human Genetics and Endocrinology, Children's Hospital of Philadelphia Research Institute, Philadelphia, USA.,Department of Genetics, University of Pennsylvania, Philadelphia, USA
| | - Thomas Reinehr
- Department of Pediatric Endocrinology, Diabetes and Nutrition Medicine, Vestische Hospital for Children and Adolescents Datteln, University of Witten/Herdecke, Datteln, Germany
| | - Diana L Cousminer
- Divisions of Human Genetics and Endocrinology, Children's Hospital of Philadelphia Research Institute, Philadelphia, USA.,Department of Genetics, University of Pennsylvania, Philadelphia, USA
| | - Johannes Hebebrand
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Heike Biebermann
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Anke Hinney
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
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Bräunig J, Dinter J, Höfig CS, Paisdzior S, Szczepek M, Scheerer P, Rosowski M, Mittag J, Kleinau G, Biebermann H. The Trace Amine-Associated Receptor 1 Agonist 3-Iodothyronamine Induces Biased Signaling at the Serotonin 1b Receptor. Front Pharmacol 2018; 9:222. [PMID: 29593543 PMCID: PMC5857711 DOI: 10.3389/fphar.2018.00222] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 02/27/2018] [Indexed: 11/13/2022] Open
Abstract
Trace amine-associated receptors (TAARs) belong to the class A G-protein-coupled receptors (GPCR) and are evolutionary related to aminergic receptors. TAARs have been identified to mediate effects of trace amines. TAAR1 signaling is mainly mediated via activation of the Gs/adenylyl cyclase pathway. In addition to classical trace amines, TAAR1 can also be activated by the thyroid hormone derivative 3-iodothyronamine (3-T1AM). Pharmacological doses of 3-T1AM induced metabolic and anapyrexic effects, which might be centrally mediated in the hypothalamus in rodents. However, the observed anapyrexic effect of 3-T1AM persists in Taar1 knock-out mice which raises the question whether further GPCRs are potential targets for 3-T1AM and mediate the observed physiological effect. Anapyrexia has been observed to be related to action on aminergic receptors such as the serotonin receptor 1b (5-HT1b). This receptor primarily activates the Gi/o mediated pathway and PLC signaling through the Gβγ of Gi/o. Since the expression profiles of TAAR1 and 5-HT1b overlap, we questioned whether 3-T1AM may activate 5-HT1b. Finally, we also evaluated heteromerization between these two GPCRs and tested signaling under co-expressed conditions. In this study, we showed, that 3-T1AM can induce Gi/o signaling through 5-HT1b in a concentration of 10 μM. Strikingly, at 5-HT1b the ligand 3-T1AM only activates the Gi/o mediated reduction of cAMP accumulation, but not PLC activation. Co-stimulation of 5-HT1b by both ligands did not lead to additive or synergistic signaling effects. In addition, we confirmed the capacity for heteromerization between TAAR1 and 5-HT1b. Under co-expression of TAAR1 and HTR1b, 3-T1AM action is only mediated via TAAR1 and activation of 5-HT1b is abrogated. In conclusion, we found evidence for 5-HT1b as a new receptor target for 3-T1AM, albeit with a different signaling effect than the endogenous ligand. Altogether, this indicates a complex interrelation of signaling effects between the investigated GPCRs and respective ligands.
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Affiliation(s)
- Julia Bräunig
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Juliane Dinter
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Carolin S Höfig
- Institute of Experimental Endocrinology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Sarah Paisdzior
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Michal Szczepek
- Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Patrick Scheerer
- Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Mark Rosowski
- Center of Brain Behavior and Metabolism, University of Lübeck, Lübeck, Germany
| | - Jens Mittag
- Institute of Biotechnology, Department Medical Biotechnology, Technical University of Berlin, Berlin, Germany
| | - Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Heike Biebermann
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
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5
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Giuranna J, Volckmar AL, Heinen A, Peters T, Schmidt B, Spieker A, Straub H, Grallert H, Müller TD, Antel J, Haußmann U, Klafki H, Liangyou R, Hebebrand J, Hinney A. The Effect of SH2B1 Variants on Expression of Leptin- and Insulin-Induced Pathways in Murine Hypothalamus. Obes Facts 2018; 11:93-108. [PMID: 29631267 PMCID: PMC5981666 DOI: 10.1159/000486962] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 01/15/2018] [Indexed: 12/30/2022] Open
Abstract
OBJECTIVE We aimed to determine the effect of human SH2B1 variants on leptin and insulin signaling, major regulators of energy homeostasis, on the RNA level. METHODS We analyzed the expression of infrequent alleles of seven SH2B1 variants (Arg67Cys, Lys150Arg, Thr175Ala, Thr343Met, Thr484Ala, Ser616Pro and Pro689Leu) in response to insulin or leptin cell stimulation. Two of these were identified in own mutation screens, the others were predicted to be deleterious or to serve as controls. The variants were analyzed in a homologous system of mouse hypothalamic cells. Changes in expression of downstream genes were measured. Student’s t-test for independent samples was applied and effect sizes using Cohen’s d were calculated. RESULTS In 34 of 54 analyzed genes involved in leptin (JAK/STAT or AKT) signaling, variants nominally changed expression. The expression of three genes was considerably increased (p values ≤ 0.001: Gbp2b (67Cys; d = 25.11), Irf9 (689Leu; d = 44.65) and Isg15 (150Arg; d = 20.35)). Of 32 analyzed genes in the insulin signaling pathway, the expression of 10 genes nominally changed (p ≤ 0.05), three resulted in p values ≤ 0.01 ( Cap1 (150Arg; d = 7.48), Mapk1 (343Met; d = –6.80) and Sorbs1 (689Leu; d = 7.82)). CONCLUSION The increased expression of genes in leptin (JAK/STAT or AKT) signaling implies that the main mode of action for human SH2B1 mutations might affect leptin signaling rather than insulin signaling.
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Affiliation(s)
- Johanna Giuranna
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Anna-Lena Volckmar
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
- Institute of Pathology, Heidelberg University Hospital, Heidelberg, Germany
| | - Anna Heinen
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Triinu Peters
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Börge Schmidt
- Institute for Medical Informatics, Biometry and Epidemiology (IMIBE), University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Anne Spieker
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Helena Straub
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Harald Grallert
- Institute of Epidemiology, Helmholtz-Zentrum Munich, Munich, Germany
| | - Timo D. Müller
- Institute of Diabetes and Obesity, Helmholtz-Zentrum Munich, Munich, Germany
| | - Jochen Antel
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Ute Haußmann
- Department of Psychiatry and Psychotherapy, Faculty of Medicine, University Hospital Essen, Essen, Germany
| | - Hans Klafki
- Department of Psychiatry and Psychotherapy, Faculty of Medicine, University Hospital Essen, Essen, Germany
- Department of Psychiatry and Psychotherapy, University Medical Center Göttingen (UMG), Georg-August-University Göttingen, Göttingen, Germany
| | - Rui Liangyou
- Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Johannes Hebebrand
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Anke Hinney
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
- *Prof. Dr. Anke Hinney, Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Wickenburgstraße 21, 45147 Essen, Germany,
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6
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Litt MJ, Okoye GD, Lark D, Cakir I, Moore C, Barber MC, Atkinson J, Fessel J, Moslehi J, Cone RD. Loss of the melanocortin-4 receptor in mice causes dilated cardiomyopathy. eLife 2017; 6:28118. [PMID: 28829041 PMCID: PMC5577919 DOI: 10.7554/elife.28118] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 07/26/2017] [Indexed: 01/04/2023] Open
Abstract
Haploinsufficiency of the melanocortin-4 receptor, the most common monogenetic obesity syndrome in humans, is associated with a reduction in autonomic tone, bradycardia, and incidence of obesity-associated hypertension. Thus, it has been assumed that melanocortin obesity syndrome may be protective with respect to obesity-associated cardiovascular disease. We show here that absence of the melanocortin-4 receptor (MC4R) in mice causes dilated cardiomyopathy, characterized by reduced contractility and increased left ventricular diameter. This cardiomyopathy is independent of obesity as weight matched diet induced obese mice do not display systolic dysfunction. Mc4r cardiomyopathy is characterized by ultrastructural changes in mitochondrial morphology and cardiomyocyte disorganization. Remarkably, testing of myocardial tissue from Mc4r-/- mice exhibited increased ADP stimulated respiratory capacity. However, this increase in respiration correlates with increased reactive oxygen species production - a canonical mediator of tissue damage. Together this study identifies MC4R deletion as a novel and potentially clinically important cause of heart failure.
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Affiliation(s)
- Michael J Litt
- Departments of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States
| | - G Donald Okoye
- Division of Cardiology, Vanderbilt University, Nashville, United States.,Cardio-Oncology Program, Department of Medicine, Vanderbilt University, Nashville, United States
| | - Daniel Lark
- Departments of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States
| | - Isin Cakir
- Life Sciences Institute, University of Michigan, Ann Arbor, United States
| | - Christy Moore
- Allergy Pulmonary and Critical Care, Vanderbilt University Department of Medicine, Nashville, United States
| | - Mary C Barber
- Division of Cardiology, Vanderbilt University, Nashville, United States.,Cardio-Oncology Program, Department of Medicine, Vanderbilt University, Nashville, United States
| | - James Atkinson
- Department of Pathology, Vanderbilt University Medical Center, Nashville, United States
| | - Josh Fessel
- Allergy Pulmonary and Critical Care, Vanderbilt University Department of Medicine, Nashville, United States
| | - Javid Moslehi
- Division of Cardiology, Vanderbilt University, Nashville, United States.,Cardio-Oncology Program, Department of Medicine, Vanderbilt University, Nashville, United States
| | - Roger D Cone
- Departments of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States.,Life Sciences Institute, University of Michigan, Ann Arbor, United States.,Department of Molecular and Integrative Physiology, University of Michigan School of Medicine, Ann Arbor, United States
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7
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Kleinau G, Müller A, Biebermann H. Oligomerization of GPCRs involved in endocrine regulation. J Mol Endocrinol 2016; 57:R59-80. [PMID: 27151573 DOI: 10.1530/jme-16-0049] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 05/04/2016] [Indexed: 12/27/2022]
Abstract
More than 800 different human membrane-spanning G-protein-coupled receptors (GPCRs) serve as signal transducers at biological barriers. These receptors are activated by a wide variety of ligands such as peptides, ions and hormones, and are able to activate a diverse set of intracellular signaling pathways. GPCRs are of central importance in endocrine regulation, which underpins the significance of comprehensively studying these receptors and interrelated systems. During the last decade, the capacity for multimerization of GPCRs was found to be a common and functionally relevant property. The interaction between GPCR monomers results in higher order complexes such as homomers (identical receptor subtype) or heteromers (different receptor subtypes), which may be present in a specific and dynamic monomer/oligomer equilibrium. It is widely accepted that the oligomerization of GPCRs is a mechanism for determining the fine-tuning and expansion of cellular processes by modification of ligand action, expression levels, and related signaling outcome. Accordingly, oligomerization provides exciting opportunities to optimize pharmacological treatment with respect to receptor target and tissue selectivity or for the development of diagnostic tools. On the other hand, GPCR heteromerization may be a potential reason for the undesired side effects of pharmacological interventions, faced with numerous and common mutual signaling modifications in heteromeric constellations. Finally, detailed deciphering of the physiological occurrence and relevance of specific GPCR/GPCR-ligand interactions poses a future challenge. This review will tackle the aspects of GPCR oligomerization with specific emphasis on family A GPCRs involved in endocrine regulation, whereby only a subset of these receptors will be discussed in detail.
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Affiliation(s)
- Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology (IEPE)Charité-Universitätsmedizin, Berlin, Germany
| | - Anne Müller
- Institute of Experimental Pediatric Endocrinology (IEPE)Charité-Universitätsmedizin, Berlin, Germany
| | - Heike Biebermann
- Institute of Experimental Pediatric Endocrinology (IEPE)Charité-Universitätsmedizin, Berlin, Germany
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8
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He S, Tao YX. Defect in MAPK signaling as a cause for monogenic obesity caused by inactivating mutations in the melanocortin-4 receptor gene. Int J Biol Sci 2014; 10:1128-37. [PMID: 25332687 PMCID: PMC4202029 DOI: 10.7150/ijbs.10359] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 09/15/2014] [Indexed: 12/22/2022] Open
Abstract
The melanocortin-4 receptor (MC4R) is a Family A G protein-coupled receptor that plays an essential role in regulating energy homeostasis, including both energy intake and expenditure. Mutations leading to a reduced MC4R function confer a major gene effect for obesity. More than 170 distinct mutations have been identified in humans. In addition to the conventional Gs-stimulated cAMP pathway, the MC4R also activates MAPKs, especially ERK1/2. We also showed there is biased signaling in the two signaling pathways, with inverse agonists in the Gs-cAMP pathway acting as agonists for the ERK1/2 pathway. In the current study, we sought to determine whether defects in basal or agonist-induced ERK1/2 activation in MC4R mutants might potentially contribute to obesity pathogenesis in patients carrying these mutations. The constitutive and ligand-stimulated ERK1/2 activation were measured in wild type and 73 naturally occurring MC4R mutations. We showed that nineteen mutants had significantly decreased basal pERK1/2 level, and five Class V variants (where no functional defects have been identified previously), C40R, V50M, T112M, A154D and S295P, had impaired ligand-stimulated ERK1/2 activation. Our studies demonstrated for the first time that decreased basal or ligand-stimulated ERK1/2 signaling might contribute to obesity pathogenesis caused by mutations in the MC4R gene. We also observed biased signaling in 25 naturally occurring mutations in the Gs-cAMP and ERK1/2 pathways.
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Affiliation(s)
- Shan He
- 1. Department of Anatomy, Physiology, and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, Alabama 36849-5519, USA. ; 2. Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, College of Fisheries, Huazhong Agricultural University, Hubei Collaborative Innovation Center for Freshwater Aquaculture, Wuhan, Hubei 430070, China
| | - Ya-Xiong Tao
- 1. Department of Anatomy, Physiology, and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, Alabama 36849-5519, USA
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9
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Karamitri A, Jockers R. Exon Sequencing of G Protein-Coupled Receptor Genes and Perspectives for Disease Treatment. METHODS IN PHARMACOLOGY AND TOXICOLOGY 2014. [DOI: 10.1007/978-1-62703-779-2_17] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
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10
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Piechowski CL, Rediger A, Lagemann C, Mühlhaus J, Müller A, Pratzka J, Tarnow P, Grüters A, Krude H, Kleinau G, Biebermann H. Inhibition of melanocortin-4 receptor dimerization by substitutions in intracellular loop 2. J Mol Endocrinol 2013; 51:109-18. [PMID: 23674133 DOI: 10.1530/jme-13-0061] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Obesity is one of the most challenging global health problems. One key player in energy homeostasis is the melanocortin-4 receptor (MC4R), which is a family A G-protein-coupled receptor (GPCR). It has recently been shown that MC4R has the capacity to form homo- or heterodimers. Dimerization of GPCRs is of great importance for signaling regulation, with major pharmacological implications. Unfortunately, not enough is yet known about the detailed structural properties of MC4R dimers or the functional consequences of receptor dimerization. Our goal, therefore, was to explore specific properties related to MC4R dimerization. First, we aimed to induce the dissociation of dimers to monomers and to compare the functional parameters of wild-type and MC4R variants. To inhibit homodimerization, we designed MC4R chimeras with the cannabinoid-1 receptor, a receptor that does not interact with MC4R. Indeed, we identified several substitutions in the intracellular loop 2 (ICL2) and adjacent regions of transmembrane helix 3 (TMH3) and TMH4 that lead to partial dimer dissociation. Interestingly, the capacity for signaling activity was generally increased in these MC4R variants, although receptor expression remained unchanged. This increase in activity for dissociated receptors might indicate a link between receptor dimerization and signaling capacity. Moreover, dimer dissociation was also observed in a naturally occurring activating MC4R mutation in ICL2. Taken together, this study provides new information on the structural prerequisites for MC4R dimerization and identifies an approach to induce the dissociation of MC4R dimers. This might be useful for further investigation of pharmacological properties.
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Affiliation(s)
- Carolin L Piechowski
- Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, Humboldt-Universität zu Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
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Melanocortin-4 Receptor in Energy Homeostasis and Obesity Pathogenesis. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 114:147-91. [DOI: 10.1016/b978-0-12-386933-3.00005-4] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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12
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Chapman KL, Findlay JBC. The melanocortin 4 receptor: oligomer formation, interaction sites and functional significance. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:535-42. [PMID: 23088915 DOI: 10.1016/j.bbamem.2012.10.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 09/14/2012] [Accepted: 10/12/2012] [Indexed: 10/27/2022]
Abstract
This study involves the structural and functional properties of the recombinant melanocortin 4 receptor (MC(4)R) expressed in the HEK-293 cell line. Using co-immuno-purification approaches, the receptor appears to be an oligomer, which can be crosslinked through disulphide bonds involving a native cysteine residue (84) to give a dimeric species. This position is located near the cytosolic region of transmembrane segment 2 and it is suggested that this is an interacting interface between MC(4)R monomers. Using co-expression of the native protein and a C84A mutant, it appears that the receptor also forms higher order oligomers via alternative interfaces. Interestingly, disulphide crosslink formation does not occur if the receptor is uncoupled from its G-protein, even though the oligomeric state is preserved. This suggests that the conformational changes, which occur on activation, affect the TM2 interface. The pharmacology of the agonist, NDP-MSH, indicates that the MC(4)R retains high affinity for the ligand in the absence of the G-protein but occupancy for the ligand is increased. The data can be interpreted to suggest that the G-protein exerts a negative allosteric effect on the receptor. Co-expression of one receptor lacking the ability to signal with another, which cannot bind the agonist, restored ligand-dependent activation of the G-protein to situations in which neither receptor on its own could activate the G-protein. Such transactivation suggests meaningful cross talk between the receptor subunits in the oligomeric complex. These studies demonstrate further unique features of the MC(4)R.
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Affiliation(s)
- Kathryn L Chapman
- Institute of Membrane and Systems Biology, Faculty of Biological Science, University of Leeds, Leeds LS2 9JT, UK.
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13
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Biebermann H, Winkler F, Handke D, Teichmann A, Gerling B, Cameron F, Eichhorst J, Grüters A, Wiesner B, Kühnen P, Krude H, Kleinau G. New pathogenic thyrotropin receptor mutations decipher differentiated activity switching at a conserved helix 6 motif of family A GPCR. J Clin Endocrinol Metab 2012; 97:E228-32. [PMID: 22112806 DOI: 10.1210/jc.2011-2106] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT In this paper we report two new TSH receptor (TSHR) mutations. One mutation (Pro639(6.50)Leu) was identified in two siblings with congenital hypothyroidism, and a second mutation (Cys636(6.47)Arg) was found in a patient suffering from nonautoimmune hyperthyroidism. Both mutations are located in transmembrane helix (TMH) 6 at the conserved Cys(6.47)-Trp(Met)(6.48)-Leu(Ala)(6.49)-Pro(6.50) motif of family A G protein-coupled receptors (GPCR). OBJECTIVE To study the pathogenic mechanisms, we tested patients' mutations and further side chain variations regarding their effects on TSHR signaling. RESULTS Substitution Pro639Leu fully inactivates the promiscuous TSHR for cAMP (Gs) and IP (Gq) signaling. In contrast, Cys636Arg leads to constitutive activation of Gs. Organization of TSHR in oligomers was not modified by mutations at position 636. Interestingly, it is known from crystal structures of GPCR that Pro(6.50) is located at a TMH6 kink-distortion, which is a pivot during activation-related helical movements. However, the cell surface expressions of all mutants at position 639 were comparable to wild type, indicating a helical conformation like wild type. CONCLUSION Until now, only naturally occurring constitutively activating mutations in TSHR TMH6 have been reported, but here we present the first pathogenic inactivating mutation (Pro639Leu). Our data are indicative of differentiated regulation of Gs and Gq signaling at particular TMH6 positions, but without any effects on TSHR oligomer constellation. Details of signaling modulation by each mutant at positions 636(6.47) and 639(6.50) help us to understand high conservation of these amino acids in family A GPCR. Described molecular (pathogenic) mechanisms are likely not unique for TSHR.
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Affiliation(s)
- Heike Biebermann
- Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, Ostring 3, Augustenburger Platz 1, 13353 Berlin, Germany
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Biebermann H, Kühnen P, Kleinau G, Krude H. The neuroendocrine circuitry controlled by POMC, MSH, and AGRP. Handb Exp Pharmacol 2012:47-75. [PMID: 22249810 DOI: 10.1007/978-3-642-24716-3_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Obesity is one of the most challenging health problems worldwide. Over the past few decades, our knowledge concerning mechanisms of weight regulation has increased tremendously leading to the identification of the leptin-melanocortin pathway. The filling level of energy stores is signaled to the brain, and the information is integrated by hypothalamic nuclei, resulting in a well-orchestrated response to food intake and energy expenditure to ensure constant body weight. One of the key players in this system is proopiomelanocortin (POMC), a precursor of a variety of neuropeptides. POMC-derived alpha- and beta-MSH play an important role in energy homeostasis by activating melanocortin receptors expressed in the arcuate nucleus (MC3R) and in the nucleus paraventricularis (MC4R). Activation of these two G protein-coupled receptors is antagonized by agouti-related peptide (AgRP). Naturally occurring mutations in this system were identified in patients suffering from common obesity as well as in patients demonstrating a phenotype of severe early-onset obesity, adrenal insufficiency, red hair, and pale skin. Detailed understanding of the complex system of POMC-AgRP-MC3R-MC4R and their interaction with other hypothalamic as well as peripheral signals is a prerequisite to combat the obesity epidemic.
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Affiliation(s)
- Heike Biebermann
- Institut für Experimentelle Pädiatrische Endokrinologie, Charité Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
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15
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Rediger A, Piechowski CL, Yi CX, Tarnow P, Strotmann R, Grüters A, Krude H, Schöneberg T, Tschöp MH, Kleinau G, Biebermann H. Mutually opposite signal modulation by hypothalamic heterodimerization of ghrelin and melanocortin-3 receptors. J Biol Chem 2011; 286:39623-31. [PMID: 21940628 PMCID: PMC3234785 DOI: 10.1074/jbc.m111.287607] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 09/03/2011] [Indexed: 12/22/2022] Open
Abstract
Interaction and cross-talk of G-protein-coupled receptors (GPCRs) are of considerable interest because an increasing number of examples implicate a profound functional and physiological relevance of homo- or hetero-oligomeric GPCRs. The ghrelin (growth hormone secretagogue receptor (GHSR)) and melanocortin-3 (MC3R) receptors are both known to have orexigenic effects on the hypothalamic control of body weight. Because in vitro studies indicate heterodimerization of GHSR and MC3R, we investigated their functional interplay. Combined in situ hybridization and immunohistochemistry indicated that the vast majority of GHSR-expressing neurons in the arcuate nucleus also express MC3R. In vitro coexpression of MC3R and GHSR promoted enhanced melanocortin-induced intracellular cAMP accumulation compared with activation of MC3R in the absence of GHSR. In contrast, agonist-independent basal signaling activity and ghrelin-induced signaling of GHSR were impaired, most likely due to interaction with MC3R. By taking advantage of naturally occurring GHSR mutations and an inverse agonist for GHSR, we demonstrate that the observed enhanced MC3R signaling capability depends directly on the basal activity of GHSR. In conclusion, we demonstrate a paradigm-shifting example of GPCR heterodimerization allowing for mutually opposite functional influence of two hypothalamic receptors controlling body weight. We found that the agonist-independent active conformation of one GPCR can determine the signaling modalities of another receptor in a heterodimer. Our discovery also implies that mutations within one of two interacting receptors might affect both receptors and different pathways simultaneously. These findings uncover mechanisms of important relevance for pharmacological targeting of GPCR in general and hypothalamic body weight regulation in particular.
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MESH Headings
- Animals
- Arcuate Nucleus of Hypothalamus/metabolism
- COS Cells
- Chlorocebus aethiops
- Cyclic AMP/genetics
- Cyclic AMP/metabolism
- Gene Expression Regulation/physiology
- Ghrelin/genetics
- Ghrelin/metabolism
- HEK293 Cells
- Humans
- Mice
- Mice, Knockout
- Mutation
- Nerve Tissue Proteins/agonists
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Neurons/metabolism
- Protein Multimerization/physiology
- Receptor, Melanocortin, Type 3/agonists
- Receptor, Melanocortin, Type 3/genetics
- Receptor, Melanocortin, Type 3/metabolism
- Receptors, Ghrelin/agonists
- Receptors, Ghrelin/genetics
- Receptors, Ghrelin/metabolism
- Signal Transduction/physiology
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Affiliation(s)
- Anne Rediger
- From the Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Carolin L. Piechowski
- From the Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Chun-Xia Yi
- the Metabolic Diseases Institute, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio 45267, and
| | - Patrick Tarnow
- From the Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Rainer Strotmann
- the Institute of Biochemistry, Medical Faculty, University of Leipzig, 04103 Leipzig, Germany
| | - Annette Grüters
- From the Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Heiko Krude
- From the Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Torsten Schöneberg
- the Institute of Biochemistry, Medical Faculty, University of Leipzig, 04103 Leipzig, Germany
| | - Matthias H. Tschöp
- the Metabolic Diseases Institute, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio 45267, and
| | - Gunnar Kleinau
- From the Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Heike Biebermann
- From the Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
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16
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Biebermann H, Winkler F, Handke D, Grüters A, Krude H, Kleinau G. Molecular description of non-autoimmune hyperthyroidism at a neonate caused by a new thyrotropin receptor germline mutation. Thyroid Res 2011; 4 Suppl 1:S8. [PMID: 21835055 PMCID: PMC3155114 DOI: 10.1186/1756-6614-4-s1-s8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Background Constitutively activating germline mutations in the thyrotropin receptor (TSHR) gene result in non-autoimmune hyperthyroidism and can be transmitted as a dominant trait or occur sporadically. These mutations are mostly located in the serpentine part of this G-protein coupled receptor. Methods Sequencing exon 9 and 10 of the thyrotropin receptor gene in a two months old patient identified a mutation which was functionally characterized after transient transfection into COS-7 cells. Cell surface localization was investigated by an ELISA approach and for signalling properties we measured cAMP by alpha screen technology for Gs/adenylyl cyclase activation and use a reporter gene assay for determination of Gq/11 phospholipase C-β activation. Results We detected a heterozygous mutation in the first extracellular loop of the TSHR gene leading to an exchange of an isoleucine residue for asparagine at amino acid position 486 (I486N). Cell surface localization was reduced to 51% of wild-type TSHR. Functional characterization of the mutant receptor revealed constitutive activation of the Gs/adenylyl cyclase pathway, in contrast basal activity of the Gq/11 pathway was comparable to the wild-type. The bovine TSH-induced cAMP accumulation was slightly reduced, but IP3 signaling was impaired. Conclusion We identified a new TSHR germline mutation (I486N) in a neonate with non-autoimmune sporadic hyperthyroidism. The mutation is located at the extracellular loop 1 and exhibits an increase in basal cAMP accumulation, but unexpectedly impairs the capability for TSH induced Gq mediated signaling. The TSHR homology model suggests isoleucine 486 as a potential key-player for induction of signal transduction by an interplay with further activation sensitive extracellular parts.
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Affiliation(s)
- Heike Biebermann
- Institute of Experimental Paediatric Endocrinology, Charité Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
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17
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Kleinau G, Hoyer I, Kreuchwig A, Haas AK, Rutz C, Furkert J, Worth CL, Krause G, Schülein R. From molecular details of the interplay between transmembrane helices of the thyrotropin receptor to general aspects of signal transduction in family a G-protein-coupled receptors (GPCRs). J Biol Chem 2011; 286:25859-71. [PMID: 21586576 PMCID: PMC3138303 DOI: 10.1074/jbc.m110.196980] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Revised: 05/10/2011] [Indexed: 12/24/2022] Open
Abstract
Transmembrane helices (TMHs) 5 and 6 are known to be important for signal transduction by G-protein-coupled receptors (GPCRs). Our aim was to characterize the interface between TMH5 and TMH6 of the thyrotropin receptor (TSHR) to gain molecular insights into aspects of signal transduction and regulation. A proline at TMH5 position 5.50 is highly conserved in family A GPCRs and causes a twist in the helix structure. Mutation of the TSHR-specific alanine (Ala-593⁵·⁵⁰) at this position to proline resulted in a 20-fold reduction of cell surface expression. This indicates that TMH5 in the TSHR might have a conformation different from most other family A GPCRs by forming a regular α-helix. Furthermore, linking our own and previous data from directed mutagenesis with structural information led to suggestions of distinct pairs of interacting residues between TMH5 and TMH6 that are responsible for stabilizing either the basal or the active state. Our insights suggest that the inactive state conformation is constrained by a core set of polar interactions among TMHs 2, 3, 6, and 7 and in contrast that the active state conformation is stabilized mainly by non-polar interactions between TMHs 5 and 6. Our findings might be relevant for all family A GPCRs as supported by a statistical analysis of residue properties between the TMHs of a vast number of GPCR sequences.
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Affiliation(s)
- Gunnar Kleinau
- Leibniz-Institut für Molekulare Pharmakologie, 13125 Berlin, Germany.
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18
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Abstract
Over the past 20 years, naturally occurring mutations that affect G protein-coupled receptors (GPCRs) have been identified, mainly in patients with endocrine diseases. The study of loss-of-function or gain-of-function mutations has contributed to our understanding of the pathophysiology of several diseases with classic hypophenotypes or hyperphenotypes of the target endocrine organs, respectively. Simultaneously, study of the mutant receptors ex vivo was instrumental in delineating the relationships between the structure and function of these important physiological and pharmacological molecules. Now that access to the crystallographic structure of a few GPCRs is available, the mechanics of these receptors can be studied at the atomic level. Progress in the fields of cell biology, molecular pharmacology and proteomics has also widened our view of GPCR functions. Initially considered simply as guanine nucleotide exchange factors capable of activating G protein-dependent regulatory cascades, GPCRs are now known to display several additional characteristics, each susceptible to alterations by disease-causing mutations. These characteristics include functionally important basal activity of the receptor; differential activation of various G proteins; differential activation of G protein-dependent and independent effects (biased agonism); interaction with proteins that modify receptor function; dimerization-dependent effects; and interaction with allosteric modulators. This Review attempts to illustrate how natural mutations of GPCR could contribute to our understanding of these novel facets of GPCR biology.
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Affiliation(s)
- Gilbert Vassart
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Faculty of Medicine, Université Libre de Bruxelles, 808 Route de Lennik, 1070 Brussels, Belgium.
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Wichard JD, ter Laak A, Krause G, Heinrich N, Kühne R, Kleinau G. Chemogenomic analysis of G-protein coupled receptors and their ligands deciphers locks and keys governing diverse aspects of signalling. PLoS One 2011; 6:e16811. [PMID: 21326864 PMCID: PMC3033908 DOI: 10.1371/journal.pone.0016811] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Accepted: 01/12/2011] [Indexed: 11/28/2022] Open
Abstract
Understanding the molecular mechanism of signalling in the important super-family of G-protein-coupled receptors (GPCRs) is causally related to questions of how and where these receptors can be activated or inhibited. In this context, it is of great interest to unravel the common molecular features of GPCRs as well as those related to an active or inactive state or to subtype specific G-protein coupling. In our underlying chemogenomics study, we analyse for the first time the statistical link between the properties of G-protein-coupled receptors and GPCR ligands. The technique of mutual information (MI) is able to reveal statistical inter-dependence between variations in amino acid residues on the one hand and variations in ligand molecular descriptors on the other. Although this MI analysis uses novel information that differs from the results of known site-directed mutagenesis studies or published GPCR crystal structures, the method is capable of identifying the well-known common ligand binding region of GPCRs between the upper part of the seven transmembrane helices and the second extracellular loop. The analysis shows amino acid positions that are sensitive to either stimulating (agonistic) or inhibitory (antagonistic) ligand effects or both. It appears that amino acid positions for antagonistic and agonistic effects are both concentrated around the extracellular region, but selective agonistic effects are cumulated between transmembrane helices (TMHs) 2, 3, and ECL2, while selective residues for antagonistic effects are located at the top of helices 5 and 6. Above all, the MI analysis provides detailed indications about amino acids located in the transmembrane region of these receptors that determine G-protein signalling pathway preferences.
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Affiliation(s)
- Jörg D. Wichard
- Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany
- Bayer-Schering Pharma, Berlin, Germany
| | | | - Gerd Krause
- Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany
| | | | - Ronald Kühne
- Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany
- * E-mail:
| | - Gunnar Kleinau
- Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
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Hebebrand J, Volckmar AL, Knoll N, Hinney A. Chipping away the 'missing heritability': GIANT steps forward in the molecular elucidation of obesity - but still lots to go. Obes Facts 2010; 3:294-303. [PMID: 20975295 PMCID: PMC6452141 DOI: 10.1159/000321537] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Although heritability of human body weight is assumed to be high, only a small fraction of the variance can as yet be attributed to molecular genetic factors. Single monogenic forms of obesity have been identified. Functionally relevant coding mutations in the melanocortin-4 receptor gene occur in 1-6% of extremely obese children and adolescents and thus represent the most common major gene effect. Genome-wide association studies (GWAS) had previously identified 14 obesity loci with genome-wide significant (p < 5 x 10-8) associations. Many of the respective genes are expressed in the central nervous system. The GIANT (Genetic Investigation of ANtropometric Traits) Consortium has now performed a meta-analysis of GWAS data based on 123,865 individuals of European ancestry followed by confirmatory analyses for the 42 best independent loci in up to 125,931 independent individuals (Speliotes et al: Association analyses of 249,796 individuals reveal eighteen new loci associated with body mass index. Nature Genetics; epub October 2010 [1]). Apart from confirming the 14 known loci, 18 novel BMI-associated loci (p < 5 x 10-8) were identified. Several of the new loci point to genes involved in key hypothalamic pathways of energy balance. The identified variants mostly have small to very small effect sizes; only 1-2% of the BMI variance is explained. Currently, a consensus explanation for this 'missing heritability' in complex diseases has not yet emerged.
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Affiliation(s)
- Johannes Hebebrand
- *Prof. Dr. Johannes Hebebrand, Department of Child and Adolescent Psychiatry, University of Duisburg-Essen, Virchowstraße 174, 45147 Essen, Germany, Tel: +49 201 7227-465, Fax -302,
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Comparative sequence and structural analyses of G-protein-coupled receptor crystal structures and implications for molecular models. PLoS One 2009; 4:e7011. [PMID: 19756152 PMCID: PMC2738427 DOI: 10.1371/journal.pone.0007011] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Accepted: 08/10/2009] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Up until recently the only available experimental (high resolution) structure of a G-protein-coupled receptor (GPCR) was that of bovine rhodopsin. In the past few years the determination of GPCR structures has accelerated with three new receptors, as well as squid rhodopsin, being successfully crystallized. All share a common molecular architecture of seven transmembrane helices and can therefore serve as templates for building molecular models of homologous GPCRs. However, despite the common general architecture of these structures key differences do exist between them. The choice of which experimental GPCR structure(s) to use for building a comparative model of a particular GPCR is unclear and without detailed structural and sequence analyses, could be arbitrary. The aim of this study is therefore to perform a systematic and detailed analysis of sequence-structure relationships of known GPCR structures. METHODOLOGY We analyzed in detail conserved and unique sequence motifs and structural features in experimentally-determined GPCR structures. Deeper insight into specific and important structural features of GPCRs as well as valuable information for template selection has been gained. Using key features a workflow has been formulated for identifying the most appropriate template(s) for building homology models of GPCRs of unknown structure. This workflow was applied to a set of 14 human family A GPCRs suggesting for each the most appropriate template(s) for building a comparative molecular model. CONCLUSIONS The available crystal structures represent only a subset of all possible structural variation in family A GPCRs. Some GPCRs have structural features that are distributed over different crystal structures or which are not present in the templates suggesting that homology models should be built using multiple templates. This study provides a systematic analysis of GPCR crystal structures and a consistent method for identifying suitable templates for GPCR homology modelling that will help to produce more reliable three-dimensional models.
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Roth CL, Ludwig M, Woelfle J, Fan ZC, Brumm H, Biebermann H, Tao YX. A novel melanocortin-4 receptor gene mutation in a female patient with severe childhood obesity. Endocrine 2009; 36:52-9. [PMID: 19214805 DOI: 10.1007/s12020-009-9156-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2008] [Revised: 12/12/2008] [Accepted: 12/15/2008] [Indexed: 12/31/2022]
Abstract
This study targeted the identification of mutations of melanocortin-4 receptor gene (MC4R) in obese children. Fifty-one unrelated probands with early onset severe obesity (body mass index (BMI) > 99th percentile; 21 girls, mean age 10.6 +/- 3.6 years) were analyzed for nucleotide variations in the MC4R coding region, by the polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) method followed by direct DNA sequencing. MC4R variants were detected in three patients: the known I169S variant was found in heterozygote state in two patients and a novel heterozygous Y302F mutation was detected in one 12-year-old girl (BMI = 34 kg/m(2), BMI z-score 2.7) who has been overweight since the second year of life and suffered from hyperinsulinemia (at the age of 12: fasting insulin 45 mU/ml, after oral glucose load max. 300 mU/ml). The mutation also appears in the father, although both parents are obese (BMI father: 30.2 kg/m(2); mother: 31.9 kg/m(2)). This novel mutation is located in the functionally important NPXXY motif of the seventh transmembrane domain of the receptor. Functional characterization revealed reduction in cell surface expression and an alteration in signal transduction properties. These results add to the growing list of loss-of-function MC4R mutations in early onset obese patients and suggest an orexigenic effect of novel Y302F mutation.
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Affiliation(s)
- Christian L Roth
- Division of Endocrinology, Seattle Children's Hospital Research Institute, Seattle, WA 98101, USA.
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Rediger A, Tarnow P, Bickenbach A, Schaefer M, Krude H, Gruters A, Biebermann H. Heterodimerization of hypothalamic G-protein-coupled receptors involved in weight regulation. Obes Facts 2009; 2:80-6. [PMID: 20054210 PMCID: PMC6444828 DOI: 10.1159/000209862] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Melanocortin 3 and 4 receptors (MC3R and MC4R) are known to play an essential role in hypothalamic weight regulation. In addition to these two G-protein-coupled receptors (GPCRs), a huge number of other GPCRs are expressed in hypothalamic regions, and some of them are involved in weight regulation. So far, homodimerization was shown for a few of these receptors. Heterodimerization of unrelated receptors may have profound functional consequence but heterodimerization of GPCRs involved in weight regulation was not reported yet. METHODS A selective number of hypothalamically expressed GPCRs were cloned into a eukaryotic expression vector. Cell surface expression was demonstrated by an ELISA approach. Subcellular distribution was investigated by confocal laser microscopy. A sandwich ELISA and fluorescence resonance energy transfer (FRET) were used to determine protein-protein interaction. RESULTS Via sandwich ELISA and FRET approach we could demonstrate a robust interaction of the MC4R with GPR7, both of which are expressed in the hypothalamic nucleus paraventricularis. Moreover, we determined a strong interaction of MC3R with the growth hormone secretagogue receptor expressed in the nucleus arcuatus. CONCLUSION Identification GPCR heterodimerization adds to the understanding of the complexity of weight regulation and may provide important information to develop therapeutic strategies to treat obesity.
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MESH Headings
- Animals
- Arcuate Nucleus of Hypothalamus/metabolism
- Body Weight/physiology
- COS Cells
- Chlorocebus aethiops
- Dimerization
- Enzyme-Linked Immunosorbent Assay
- Fluorescence Resonance Energy Transfer
- Gene Expression/physiology
- Humans
- Kidney/cytology
- Obesity/genetics
- Obesity/metabolism
- Obesity/physiopathology
- Paraventricular Hypothalamic Nucleus/metabolism
- Receptor, Cannabinoid, CB1/chemistry
- Receptor, Cannabinoid, CB1/genetics
- Receptor, Cannabinoid, CB1/metabolism
- Receptor, Melanocortin, Type 3/chemistry
- Receptor, Melanocortin, Type 3/genetics
- Receptor, Melanocortin, Type 3/metabolism
- Receptor, Melanocortin, Type 4/chemistry
- Receptor, Melanocortin, Type 4/genetics
- Receptor, Melanocortin, Type 4/metabolism
- Receptor, Serotonin, 5-HT1B/chemistry
- Receptor, Serotonin, 5-HT1B/genetics
- Receptor, Serotonin, 5-HT1B/metabolism
- Receptors, Cell Surface/chemistry
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Receptors, G-Protein-Coupled/chemistry
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Neuropeptide/chemistry
- Receptors, Neuropeptide/genetics
- Receptors, Neuropeptide/metabolism
- Receptors, Neuropeptide Y/chemistry
- Receptors, Neuropeptide Y/genetics
- Receptors, Neuropeptide Y/metabolism
- Receptors, Opioid, mu/chemistry
- Receptors, Opioid, mu/genetics
- Receptors, Opioid, mu/metabolism
- Receptors, Peptide/chemistry
- Receptors, Peptide/genetics
- Receptors, Peptide/metabolism
- Transfection
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Affiliation(s)
- Anne Rediger
- Institute of Experimental Pediatric Endocrinology, Charité - Universitatsmedizin Berlin, Germany
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Tao Y. Chapter 6 Mutations in Melanocortin‐4 Receptor and Human Obesity. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2009; 88:173-204. [DOI: 10.1016/s1877-1173(09)88006-x] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Kirchner H, Nogueiras R. GOAT: a stomach enzyme that whets our appetite. Obes Facts 2008; 1:123-6. [PMID: 20054171 PMCID: PMC6452120 DOI: 10.1159/000139141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
| | - Ruben Nogueiras
- *Dr. Ruben Nogueiras, Department of Psychiatry, Obesity Research Centre/Genome Research Institute, University of Cincinnati, 2180 East Galbraith Road, Building D, Room 211, Cincinnati, OH 45237, USA, Tel: +1 513 558 86–58, Fax -56, E-mail
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