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Renard E, Thevenard-Berger A, Meyre D. Medical semiology of patients with monogenic obesity: A systematic review. Obes Rev 2024; 25:e13797. [PMID: 38956946 DOI: 10.1111/obr.13797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 03/20/2024] [Accepted: 06/19/2024] [Indexed: 07/04/2024]
Abstract
Patients with monogenic obesity display numerous medical features on top of hyperphagic obesity, but no study to date has provided an exhaustive description of their semiology. Two reviewers independently conducted a systematic review of MEDLINE, Embase, and Web of Science Core Collection databases from inception to January 2022 to identify studies that described symptoms of patients carrying pathogenic mutations in at least one of eight monogenic obesity genes (ADCY3, LEP, LEPR, MC3R, MC4R, MRAP2, PCSK1, and POMC). Of 5207 identified references, 269 were deemed eligible after title and abstract screening, full-text reading, and risk of bias and quality assessment. Data extraction included mutation spectrum and mode of inheritance, clinical presentation (e.g., anthropometry, energy intake and eating behaviors, digestive function, puberty and fertility, cognitive features, infectious diseases, morphological characteristics, chronic respiratory disease, and cardiovascular disease), biological characteristics (metabolic profile, endocrinology, hematology), radiological features, and treatments. The review provides an exhaustive description of mandatory, non-mandatory, and unique symptoms in heterozygous and homozygous carriers of mutation in eight monogenic obesity genes. This information is critical to help clinicians to orient genetic testing in subsets of patients with suspected monogenic obesity and provide actionable treatments (e.g., recombinant leptin and MC4R agonist).
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Affiliation(s)
- Emeline Renard
- INSERM UMR_S 1256, Nutrition, Genetics, and Environmental Risk Exposure (NGERE), Faculty of Medicine of Nancy, University of Lorraine, Nancy, France
- Department of Pediatrics, University Hospital of Nancy, Nancy, France
| | | | - David Meyre
- INSERM UMR_S 1256, Nutrition, Genetics, and Environmental Risk Exposure (NGERE), Faculty of Medicine of Nancy, University of Lorraine, Nancy, France
- Department of Molecular Medicine, Division of Biochemistry, Molecular Biology, and Nutrition, University Hospital of Nancy, Nancy, France
- Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Canada
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2
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Anthofer L, Gmach P, Uretmen Kagiali ZC, Kleinau G, Rotter J, Opitz R, Scheerer P, Beck-Sickinger AG, Wolf P, Biebermann H, Bechmann I, Kühnen P, Krude H, Paisdzior S. Melanocortin-4 Receptor PLC Activation Is Modulated by an Interaction with the Monocarboxylate Transporter 8. Int J Mol Sci 2024; 25:7565. [PMID: 39062808 PMCID: PMC11277258 DOI: 10.3390/ijms25147565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2024] [Revised: 07/05/2024] [Accepted: 07/06/2024] [Indexed: 07/28/2024] Open
Abstract
The melanocortin-4 receptor (MC4R) is a key player in the hypothalamic leptin-melanocortin pathway that regulates satiety and hunger. MC4R belongs to the G protein-coupled receptors (GPCRs), which are known to form heterodimers with other membrane proteins, potentially modulating receptor function or characteristics. Like MC4R, thyroid hormones (TH) are also essential for energy homeostasis control. TH transport across membranes is facilitated by the monocarboxylate transporter 8 (MCT8), which is also known to form heterodimers with GPCRs. Based on the finding in single-cell RNA-sequencing data that both proteins are simultaneously expressed in hypothalamic neurons, we investigated a putative interplay between MC4R and MCT8. We developed a novel staining protocol utilizing a fluorophore-labeled MC4R ligand and demonstrated a co-localization of MC4R and MCT8 in human brain tissue. Using in vitro assays such as BRET, IP1, and cAMP determination, we found that MCT8 modulates MC4R-mediated phospholipase C activation but not cAMP formation via a direct interaction, an effect that does not require a functional MCT8 as it was not altered by a specific MCT8 inhibitor. This suggests an extended functional spectrum of MCT8 as a GPCR signaling modulator and argues for the investigation of further GPCR-protein interactions with hitherto underrepresented physiological functions.
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Affiliation(s)
- Larissa Anthofer
- Institute of Experimental Pediatric Endocrinology, Charité—Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany
- Institute of Anatomy, Leipzig University, D-04103 Leipzig, Germany
| | - Philipp Gmach
- Institute of Experimental Pediatric Endocrinology, Charité—Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany
| | - Zeynep Cansu Uretmen Kagiali
- Institute of Experimental Pediatric Endocrinology, Charité—Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany
| | - Gunnar Kleinau
- Group Structural Biology of Cellular Signaling, Institute of Medical Physics and Biophysics, Charité—Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany
| | - Jonas Rotter
- Institute of Anatomy, Leipzig University, D-04103 Leipzig, Germany
| | - Robert Opitz
- Institute of Experimental Pediatric Endocrinology, Charité—Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany
| | - Patrick Scheerer
- Group Structural Biology of Cellular Signaling, Institute of Medical Physics and Biophysics, Charité—Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany
| | | | - Philipp Wolf
- Faculty of Life Sciences, Institute of Biochemistry, Leipzig University, D-04103 Leipzig, Germany
| | - Heike Biebermann
- Institute of Experimental Pediatric Endocrinology, Charité—Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany
| | - Ingo Bechmann
- Institute of Anatomy, Leipzig University, D-04103 Leipzig, Germany
| | - Peter Kühnen
- Department for Pediatric Endocrinology and Diabetology, Charité—Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany
| | - Heiko Krude
- Institute of Experimental Pediatric Endocrinology, Charité—Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany
| | - Sarah Paisdzior
- Institute of Experimental Pediatric Endocrinology, Charité—Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, D-10117 Berlin, Germany
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3
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Bernard A, Ojeda Naharros I, Yue X, Mifsud F, Blake A, Bourgain-Guglielmetti F, Ciprin J, Zhang S, McDaid E, Kim K, Nachury MV, Reiter JF, Vaisse C. MRAP2 regulates energy homeostasis by promoting primary cilia localization of MC4R. JCI Insight 2023; 8:e155900. [PMID: 36692018 PMCID: PMC9977312 DOI: 10.1172/jci.insight.155900] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 11/30/2022] [Indexed: 01/24/2023] Open
Abstract
The G protein-coupled receptor melanocortin-4 receptor (MC4R) and its associated protein melanocortin receptor-associated protein 2 (MRAP2) are essential for the regulation of food intake and body weight in humans. MC4R localizes and functions at the neuronal primary cilium, a microtubule-based organelle that senses and relays extracellular signals. Here, we demonstrate that MRAP2 is critical for the weight-regulating function of MC4R neurons and the ciliary localization of MC4R. More generally, our study also reveals that GPCR localization to primary cilia can require specific accessory proteins that may not be present in heterologous cell culture systems. Our findings further demonstrate that targeting of MC4R to neuronal primary cilia is essential for the control of long-term energy homeostasis and suggest that genetic disruption of MC4R ciliary localization may frequently underlie inherited forms of obesity.
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Affiliation(s)
| | | | - Xinyu Yue
- Department of Medicine and The Diabetes Center
| | | | - Abbey Blake
- Department of Medicine and The Diabetes Center
| | | | | | - Sumei Zhang
- Department of Medicine and The Diabetes Center
| | - Erin McDaid
- Department of Medicine and The Diabetes Center
| | - Kellan Kim
- Department of Medicine and The Diabetes Center
| | | | - Jeremy F. Reiter
- Department of Biochemistry and Biophysics, Cardiovascular Research Institute, UCSF, San Francisco, California, USA
- Chan Zuckerberg Biohub, San Francisco, California, USA
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Banik S. Genetic, Epigenetic, and Molecular Biology of Obesity: From Pathology to Therapeutics the Way Forward. JOURNAL OF THE ASSOCIATION OF PHYSICIANS OF INDIA 2022; 70:11-12. [DOI: 10.5005/japi-11001-0080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Evaluation of Pharmacological Rescue of Melanocortin-4 Receptor Nonsense Mutations by Aminoglycoside. Life (Basel) 2022; 12:life12111793. [PMID: 36362948 PMCID: PMC9697516 DOI: 10.3390/life12111793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 10/18/2022] [Accepted: 11/02/2022] [Indexed: 11/09/2022] Open
Abstract
The melanocortin-4 receptor (MC4R) is critical for central satiety regulation, therefore presenting a potent target for pharmacological obesity treatment. Melanocortin-4 receptor mutations prevalently cause monogenetic obesity. A possibility of overcoming stop mutations is aminoglycoside-mediated translational readthrough. Promising results were achieved in COS-7 cells, but data for human cell systems are still missing, so uncertainty surrounds this potential treatment. In transfected HEK-293 cells, we tested whether translational readthrough by aminoglycoside Geneticin combined with high-affinity ligand setmelanotide, which is effective in proopiomelanocortin or leptin receptor deficiency patients, is a treatment option for affected patients. Five MC4R nonsense mutants (W16X, Y35X_D37V, E61X, W258X, Q307X) were investigated. Confocal microscopy and cell surface expression assays revealed the importance of the mutations’ position within the MC4R. N-terminal mutants were marginally expressed independent of Geneticin treatment, whereas mutants with nonsense mutations in transmembrane helix 6 or helix 8 showed wild-type-like expression. For functional analysis, Gs and Gq/11 signaling were measured. N-terminal mutants (W16X, Y35X_D37V) showed no cAMP formation after challenge with alpha-MSH or setmelanotide, irrespective of Geneticin treatment. Similarly, Gs activation was almost impossible in W258X and Q307X with wild-type-like cell surface expression. Results for Gq/11 signaling were comparable. Based on our data, this approach improbably represents a therapeutic option.
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Fullone MR, Maftei D, Vincenzi M, Lattanzi R, Miele R. Arginine 125 Is an Essential Residue for the Function of MRAP2. Int J Mol Sci 2022; 23:9853. [PMID: 36077245 PMCID: PMC9456287 DOI: 10.3390/ijms23179853] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 08/25/2022] [Accepted: 08/27/2022] [Indexed: 11/16/2022] Open
Abstract
MRAP2 is a small simple transmembrane protein arranged in a double antiparallel topology on the plasma membrane. It is expressed in the paraventricular nucleus of the hypothalamus, where it interacts with various G protein-coupled receptors, such as the prokineticin receptors, and regulates energy expenditure and appetite. The aim of this work was to analyze the functional role of the specific arginine residue at position 125 of MRAP2, which affects protein conformation, dimer formation, and PKR2 binding. Results obtained with the MRAP2 mutants R125H and R125C, which are found in human patients with extreme obesity, and mouse MRAP2, in which arginine 125 is normally replaced by histidine, were compared with those obtained with human MRAP2. Understanding the mechanism by which MRAP2 regulates G protein-coupled receptors helps in elucidating the metabolic pathways involved in metabolic dysfunction and in developing new drugs as specific targets of the MRAP2-PKR2 complex.
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Affiliation(s)
- Maria Rosaria Fullone
- Department of Biochemical Sciences “Alessandro Rossi Fanelli”, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Rome, Italy
| | - Daniela Maftei
- Department of Physiology and Pharmacology “Vittorio Erspamer”, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Rome, Italy
| | - Martina Vincenzi
- Department of Physiology and Pharmacology “Vittorio Erspamer”, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Rome, Italy
| | - Roberta Lattanzi
- Department of Physiology and Pharmacology “Vittorio Erspamer”, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Rome, Italy
| | - Rossella Miele
- Department of Biochemical Sciences “Alessandro Rossi Fanelli”, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Rome, Italy
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Reininghaus N, Paisdzior S, Höpfner F, Jyrch S, Cetindag C, Scheerer P, Kühnen P, Biebermann H. A Setmelanotide-like Effect at MC4R Is Achieved by MC4R Dimer Separation. Biomolecules 2022; 12:biom12081119. [PMID: 36009013 PMCID: PMC9405727 DOI: 10.3390/biom12081119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 08/11/2022] [Accepted: 08/12/2022] [Indexed: 01/22/2023] Open
Abstract
Melanocortin 4 receptor (MC4R) is part of the leptin-melanocortin pathway and plays an essential role in mediating energy homeostasis. Mutations in the MC4R are the most frequent monogenic cause for obesity. Due to increasing numbers of people with excess body weight, the MC4R has become a target of interest in the search of treatment options. We have previously reported that the MC4R forms homodimers, affecting receptor Gs signaling properties. Recent studies introducing setmelanotide, a novel synthetic MC4R agonist, suggest a predominant role of the Gq/11 pathway regarding weight regulation. In this study, we analyzed effects of inhibiting homodimerization on Gq/11 signaling using previously reported MC4R/CB1R chimeras. NanoBRETTM studies to determine protein–protein interaction were conducted, confirming decreased homodimerization capacities of chimeric receptors in HEK293 cells. Gq/11 signaling of chimeric receptors was analyzed using luciferase-based reporter gene (NFAT) assays. Results demonstrate an improvement of alpha-MSH-induced NFAT signaling of chimeras, reaching the level of setmelanotide signaling at wild-type MC4R (MC4R-WT). In summary, our study shows that inhibiting homodimerization has a setmelanotide-like effect on Gq/11 signaling, with chimeric receptors presenting increased potency compared to MC4R-WT. These findings indicate the potential of inhibiting MC4R homodimerization as a therapeutic target to treat obesity.
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Affiliation(s)
- Nanina Reininghaus
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Experimental Pediatric Endocrinology, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Sarah Paisdzior
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Experimental Pediatric Endocrinology, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Friederike Höpfner
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Experimental Pediatric Endocrinology, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Sabine Jyrch
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Experimental Pediatric Endocrinology, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Cigdem Cetindag
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Experimental Pediatric Endocrinology, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Patrick Scheerer
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, 10117 Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, 13353 Berlin, Germany
| | - Peter Kühnen
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Experimental Pediatric Endocrinology, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Heike Biebermann
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Experimental Pediatric Endocrinology, Augustenburger Platz 1, 13353 Berlin, Germany
- Correspondence:
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8
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Ouhrouch A, Boitard S, Boyer F, Servin B, Da Silva A, Pompanon F, Haddioui A, Benjelloun B. Genomic Uniqueness of Local Sheep Breeds From Morocco. Front Genet 2021; 12:723599. [PMID: 34925440 PMCID: PMC8675355 DOI: 10.3389/fgene.2021.723599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 11/09/2021] [Indexed: 01/17/2023] Open
Abstract
Sheep farming is a major source of meat in Morocco and plays a key role in the country's agriculture. This study aims at characterizing the whole-genome diversity and demographic history of the main Moroccan sheep breeds, as well as to identify selection signatures within and between breeds. Whole genome data from 87 individuals representing the five predominant local breeds were used to estimate their level of neutral genetic diversity and to infer the variation of their effective population size over time. In addition, we used two methods to detect selection signatures: either for detecting selective sweeps within each breed separately or by detecting differentially selected regions by contrasting different breeds. We identified hundreds of genomic regions putatively under selection, which related to several biological terms involved in local adaptation or the expression of zootechnical performances such as Growth, UV protection, Cell maturation or Feeding behavior. The results of this study revealed selection signatures in genes that have an important role in traits of interest and increased our understanding of how genetic diversity is distributed in these local breeds. Thus, Moroccan local sheep breeds exhibit both a high genetic diversity and a large set of adaptive variations, and therefore, represent a valuable genetic resource for the conservation of sheep in the context of climate change.
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Affiliation(s)
- Abdessamad Ouhrouch
- Livestock Genomics Laboratory, Regional Center of Agricultural Research Tadla, National Institute of Agricultural Research INRA, Rabat, Morocco.,Biotechnologies and Valorization of Plant-Genetic Resources Laboratory, Sultan Moulay Slimane University, Beni Mellal, Morocco
| | - Simon Boitard
- CBGP, Université de Montpellier, CIRAD, INRAE, Institut Agro, IRD, Montpellier, France
| | - Frédéric Boyer
- Université Grenoble Alpes, Université Savoie MT-Blanc, CNRS, LECA, Grenoble, France
| | - Bertrand Servin
- GenPhySE, Université de Toulouse, INRA, INPT, INP-ENVT, Castanet-Tolosan, France
| | - Anne Da Silva
- PEREINE/E2LIM, Faculty of Science and Technics, Limoges, France
| | - François Pompanon
- Université Grenoble Alpes, Université Savoie MT-Blanc, CNRS, LECA, Grenoble, France
| | - Abdelmajid Haddioui
- Biotechnologies and Valorization of Plant-Genetic Resources Laboratory, Sultan Moulay Slimane University, Beni Mellal, Morocco
| | - Badr Benjelloun
- Livestock Genomics Laboratory, Regional Center of Agricultural Research Tadla, National Institute of Agricultural Research INRA, Rabat, Morocco
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Powell DR, Revelli JP, Doree DD, DaCosta CM, Desai U, Shadoan MK, Rodriguez L, Mullens M, Yang QM, Ding ZM, Kirkpatrick LL, Vogel P, Zambrowicz B, Sands AT, Platt KA, Hansen GM, Brommage R. High-Throughput Screening of Mouse Gene Knockouts Identifies Established and Novel High Body Fat Phenotypes. Diabetes Metab Syndr Obes 2021; 14:3753-3785. [PMID: 34483672 PMCID: PMC8409770 DOI: 10.2147/dmso.s322083] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 08/04/2021] [Indexed: 01/05/2023] Open
Abstract
PURPOSE Obesity is a major public health problem. Understanding which genes contribute to obesity may better predict individual risk and allow development of new therapies. Because obesity of a mouse gene knockout (KO) line predicts an association of the orthologous human gene with obesity, we reviewed data from the Lexicon Genome5000TM high throughput phenotypic screen (HTS) of mouse gene KOs to identify KO lines with high body fat. MATERIALS AND METHODS KO lines were generated using homologous recombination or gene trapping technologies. HTS body composition analyses were performed on adult wild-type and homozygous KO littermate mice from 3758 druggable mouse genes having a human ortholog. Body composition was measured by either DXA or QMR on chow-fed cohorts from all 3758 KO lines and was measured by QMR on independent high fat diet-fed cohorts from 2488 of these KO lines. Where possible, comparisons were made to HTS data from the International Mouse Phenotyping Consortium (IMPC). RESULTS Body fat data are presented for 75 KO lines. Of 46 KO lines where independent external published and/or IMPC KO lines are reported as obese, 43 had increased body fat. For the remaining 29 novel high body fat KO lines, Ksr2 and G2e3 are supported by data from additional independent KO cohorts, 6 (Asnsd1, Srpk2, Dpp8, Cxxc4, Tenm3 and Kiss1) are supported by data from additional internal cohorts, and the remaining 21 including Tle4, Ak5, Ntm, Tusc3, Ankk1, Mfap3l, Prok2 and Prokr2 were studied with HTS cohorts only. CONCLUSION These data support the finding of high body fat in 43 independent external published and/or IMPC KO lines. A novel obese phenotype was identified in 29 additional KO lines, with 27 still lacking the external confirmation now provided for Ksr2 and G2e3 KO mice. Undoubtedly, many mammalian obesity genes remain to be identified and characterized.
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Affiliation(s)
- David R Powell
- Department of Pharmaceutical Biology, Lexicon Pharmaceuticals, Inc, The Woodlands, TX, USA
| | - Jean-Pierre Revelli
- Department of Pharmaceutical Biology, Lexicon Pharmaceuticals, Inc, The Woodlands, TX, USA
| | - Deon D Doree
- Department of Pharmaceutical Biology, Lexicon Pharmaceuticals, Inc, The Woodlands, TX, USA
| | - Christopher M DaCosta
- Department of Pharmaceutical Biology, Lexicon Pharmaceuticals, Inc, The Woodlands, TX, USA
| | - Urvi Desai
- Department of Pharmaceutical Biology, Lexicon Pharmaceuticals, Inc, The Woodlands, TX, USA
| | - Melanie K Shadoan
- Department of Pharmaceutical Biology, Lexicon Pharmaceuticals, Inc, The Woodlands, TX, USA
| | - Lawrence Rodriguez
- Department of Information Technology, Lexicon Pharmaceuticals, Inc, The Woodlands, Tx, USA
| | - Michael Mullens
- Department of Information Technology, Lexicon Pharmaceuticals, Inc, The Woodlands, Tx, USA
| | - Qi M Yang
- Department of Pharmaceutical Biology, Lexicon Pharmaceuticals, Inc, The Woodlands, TX, USA
| | - Zhi-Ming Ding
- Department of Pharmaceutical Biology, Lexicon Pharmaceuticals, Inc, The Woodlands, TX, USA
| | - Laura L Kirkpatrick
- Department of Molecular Biology, Lexicon Pharmaceuticals, Inc, The Woodlands, Tx, USA
| | - Peter Vogel
- Department of Pharmaceutical Biology, Lexicon Pharmaceuticals, Inc, The Woodlands, TX, USA
| | - Brian Zambrowicz
- Department of Pharmaceutical Biology, Lexicon Pharmaceuticals, Inc, The Woodlands, TX, USA
- Department of Information Technology, Lexicon Pharmaceuticals, Inc, The Woodlands, Tx, USA
- Department of Molecular Biology, Lexicon Pharmaceuticals, Inc, The Woodlands, Tx, USA
| | - Arthur T Sands
- Department of Pharmaceutical Biology, Lexicon Pharmaceuticals, Inc, The Woodlands, TX, USA
- Department of Information Technology, Lexicon Pharmaceuticals, Inc, The Woodlands, Tx, USA
- Department of Molecular Biology, Lexicon Pharmaceuticals, Inc, The Woodlands, Tx, USA
| | - Kenneth A Platt
- Department of Molecular Biology, Lexicon Pharmaceuticals, Inc, The Woodlands, Tx, USA
| | - Gwenn M Hansen
- Department of Molecular Biology, Lexicon Pharmaceuticals, Inc, The Woodlands, Tx, USA
| | - Robert Brommage
- Department of Pharmaceutical Biology, Lexicon Pharmaceuticals, Inc, The Woodlands, TX, USA
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10
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Study of LEP, MRAP2 and POMC genes as potential causes of severe obesity in Brazilian patients. Eat Weight Disord 2021; 26:1399-1408. [PMID: 32578125 DOI: 10.1007/s40519-020-00946-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Accepted: 06/11/2020] [Indexed: 10/24/2022] Open
Abstract
PURPOSE Monogenic forms of obesity are caused by single-gene variants which affect the energy homeostasis by increasing food intake and decreasing energy expenditure. Most of these variants result from disruption of the leptin-melanocortin signaling, which can cause severe early-onset obesity and hyperphagia. These mutation have been identified in genes encoding essential proteins to this pathway, including leptin (LEP), melanocortin 2 receptor accessory proteins 2 (MRAP2) and proopiomelanocortin (POMC). We aimed to investigate the prevalence of LEP, MRAP2 and POMC rare variants in severely obese adults, who developed obesity during childhood. To the best of our knowledge, this is the first study screening rare variants of these genes in patients from Brazil. METHODS A total of 122 Brazilian severely obese patients (BMI ≥ 35 kg/m2) were screened for the coding regions of LEP, MRAP2 and POMC by Sanger sequencing. All patients are candidates to the bariatric surgery. Clinical characteristics were described in patients with novel and/or potentially pathogenic variants. RESULTS Sixteen different variants were identified in these genes, of which two were novel. Among them, one previous variant with potentially deleterious effect in MRAP2 (p.Arg125Cys) was found. In addition, two heterozygous mutations in POMC (p.Phe87Leu and p.Arg90Leu) were predicted to impair protein function. We also observed a POMC homozygous 9 bp insertion (p.Gly99_Ala100insSerSerGly) in three patients. No pathogenic variant was observed in LEP. CONCLUSION Our study described for the first time the prevalence of rare potentially pathogenic MRAP2 and POMC variants in a cohort of Brazilian severely obese adults. LEVEL OF EVIDENCE Level V, cross-sectional descriptive study.
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11
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Bouchard C. Genetics of Obesity: What We Have Learned Over Decades of Research. Obesity (Silver Spring) 2021; 29:802-820. [PMID: 33899337 DOI: 10.1002/oby.23116] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 12/15/2020] [Accepted: 12/16/2020] [Indexed: 12/14/2022]
Abstract
There is a genetic component to human obesity that accounts for 40% to 50% of the variability in body weight status but that is lower among normal weight individuals (about 30%) and substantially higher in the subpopulation of individuals with obesity and severe obesity (about 60%-80%). The appreciation that heritability varies across classes of BMI represents an important advance. After controlling for BMI, ectopic fat and fat distribution traits are characterized by heritability levels ranging from 30% to 55%. Defects in at least 15 genes are the cause of monogenic obesity cases, resulting mostly from deficiencies in the leptin-melanocortin signaling pathway. Approximately two-thirds of the BMI heritability can be imputed to common DNA variants, whereas low-frequency and rare variants explain the remaining fraction. Diminishing allele effect size is observed as the number of obesity-associated variants expands, with most BMI-increasing or -decreasing alleles contributing only a few grams or less to body weight. Obesity-promoting alleles exert minimal effects in normal weight individuals but have larger effects in individuals with a proneness to obesity, suggesting a higher penetrance; however, it is not known whether these larger effect sizes precede obesity or are caused by an obese state. The obesity genetic risk is conditioned by thousands of DNA variants that make genetically based obesity prevention and treatment a major challenge.
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Affiliation(s)
- Claude Bouchard
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA
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12
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MRAP2 Interaction with Melanocortin-4 Receptor in SnakeHead ( Channa argus). Biomolecules 2021; 11:biom11030481. [PMID: 33807040 PMCID: PMC8004712 DOI: 10.3390/biom11030481] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 03/11/2021] [Accepted: 03/19/2021] [Indexed: 02/06/2023] Open
Abstract
The melanocortin-4 receptor (MC4R) plays an important role in the regulation of food intake and energy expenditure. Melanocortin-2 receptor accessory protein 2 (MRAP2) modulates trafficking, ligand binding, and signaling of MC4R. The Northern snakehead (Channa argus) is an economically important freshwater fish native to East Asia. To explore potential interaction between snakehead MC4R and MRAP2, herein we cloned snakehead mc4r and mrap2. The snakehead mc4r consisted of a 984 bp open reading frame encoding a protein of 327 amino acids, while snakehead mrap2 contained a 693 bp open reading frame encoding a protein of 230 amino acids. Synteny analysis indicated that mc4r was highly conserved with similar gene arrangement, while mrap2 contained two isoforms in teleost with different gene orders. Snakehead mc4r was primarily expressed in the brain, whereas mrap2 was expressed in the brain and intestine. Snakehead mc4r and mrap2 expression was modulated by fasting and refeeding. Further pharmacological experiments showed that the cloned snakehead MC4R was functional, capable of binding to peptide agonists and increasing intracellular cAMP production in a dose-dependent manner. Snakehead MC4R exhibited high constitutive activity. MRAP2 significantly decreased basal and agonist-stimulated cAMP signaling. These findings suggest that snakehead MC4R might be involved in energy balance regulation by interacting with MRAP2. Further studies are needed to elucidate MC4R in regulating diverse physiological processes in snakehead.
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13
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Tai X, Xue S, Zhang C, Liu Y, Chen J, Han Y, Lin G, Zhang C. Pharmacological evaluation of MRAP proteins on Xenopus neural melanocortin signaling. J Cell Physiol 2021; 236:6344-6361. [PMID: 33521982 DOI: 10.1002/jcp.30306] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 01/13/2021] [Accepted: 01/20/2021] [Indexed: 12/14/2022]
Abstract
Melanocortin-3 receptor (MC3R) and melanocortin-4 receptor (MC4R), two neural G protein-coupled receptors are known to be functionally critical for energy balance in vertebrates. As allosteric regulators of melanocortin receptors, melanocortin accessory proteins (MRAPs) are also involved in energy homeostasis. The interaction of MRAPs and melanocortin signaling was previously shown in mammals and zebrafish, but nothing had been reported in amphibians. As the basal class of tetrapods, amphibians occupy a phylogenetic transition between teleosts and terrestrial animals. Here we examined the evolutionary conservation of MC3R, MC4R, and MRAPs between diploid Xenopus tropicalis (xt-) and other chordates and investigated the pharmacological regulatory properties of MRAPs on the neural MC3R and MC4R signaling. Our results showed that xtMRAP and xtMRAP2 both exerted robust potentiation effect on agonist (α-MSH and adrenocorticotropin [ACTH]) induced activation and modulated the basal activity and cell surface translocation of xtMC3R and xtMC4R. In addition, the presence of two accessory proteins could convert xtMC3R and xtMC4R into ACTH-preferred receptors. These findings suggest that the presence of MRAPs exhibits fine control over the pharmacological activities of the neuronal MC3R and MC4R signaling in the Xenopus tropicalis, which is physiologically relevant with the complicated transition of feeding behaviors during their life history.
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Affiliation(s)
- Xiaolu Tai
- Shanghai Key Laboratory of Signaling and Disease Research, Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Song Xue
- Shanghai Key Laboratory of Signaling and Disease Research, Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Cong Zhang
- Shanghai Key Laboratory of Signaling and Disease Research, Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Yu Liu
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopedic Department of Tongji Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Jie Chen
- Shanghai Key Laboratory of Signaling and Disease Research, Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Yu Han
- Shanghai Key Laboratory of Signaling and Disease Research, Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Gufa Lin
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopedic Department of Tongji Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Chao Zhang
- Shanghai Key Laboratory of Signaling and Disease Research, Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
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14
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Berruien NNA, Smith CL. Emerging roles of melanocortin receptor accessory proteins (MRAP and MRAP2) in physiology and pathophysiology. Gene 2020; 757:144949. [PMID: 32679290 DOI: 10.1016/j.gene.2020.144949] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 07/08/2020] [Accepted: 07/09/2020] [Indexed: 01/07/2023]
Abstract
Melanocortin-2 receptor accessory protein (MRAP) has an unusual dual topology and influences the expression, localisation, signalling and internalisation of the melanocortin receptor 2 (MC2); the adrenocorticotropic hormone (ACTH) receptor. Mutations in MRAP are associated with familial glucocorticoid deficiency type-2 and evidence is emerging of the importance of MRAP in adrenal development and ACTH signalling. Human MRAP has two functional splice variants: MRAP-α and MRAP-β, unlike MRAP-β, MRAP-α has little expression in brain but is highly expressed in ovary. MRAP2, identified through whole human genome sequence analysis, has approximately 40% sequence homology to MRAP. MRAP2 facilitates MC2 localisation to the cell surface but not ACTH signalling. MRAP and MRAP2 have been found to regulate the surface expression and signalling of all melanocortin receptors (MC1-5). Additionally, MRAP2 moderates the signalling of the G-protein coupled receptors (GCPRs): orexin, prokineticin and GHSR1a; the ghrelin receptor. Whilst MRAP appears to be mainly involved in glucocorticoid synthesis, an important role is emerging for MRAP2 in regulating appetite and energy homeostasis. Transgenic models indicate the importance of MRAP in adrenal gland formation. Like MC3R and MC4R knockout mice, MRAP2 knockout mice have an obese phenotype. In vitro studies indicate that MRAP2 enhances the MC3 and MC4 response to the agonist αMSH, which, like ACTH, is produced through precursor polypeptide proopiomelanocortin (POMC) cleavage. Analysis of cohorts of individuals with obesity have revealed several MRAP2 genetic variants with loss of function mutations which are causative of monogenic hyperphagic obesity with hyperglycaemia and hypertension. MRAP2 may also be associated with female infertility. This review summarises current knowledge of MRAP and MRAP2, their influence on GPCR signalling, and focusses on pathophysiology, particularly familial glucocorticoid deficiency type-2 and obesity.
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Affiliation(s)
- Nasrin N A Berruien
- School of Life Sciences, University of Westminster, 115 New Cavendish Street, London W1W 6UW, UK.
| | - Caroline L Smith
- School of Life Sciences, University of Westminster, 115 New Cavendish Street, London W1W 6UW, UK.
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15
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Yang Y, Xu Y. The central melanocortin system and human obesity. J Mol Cell Biol 2020; 12:785-797. [PMID: 32976556 PMCID: PMC7816681 DOI: 10.1093/jmcb/mjaa048] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 08/04/2020] [Accepted: 08/14/2020] [Indexed: 12/13/2022] Open
Abstract
The prevalence of obesity and the associated comorbidities highlight the importance of understanding the regulation of energy homeostasis. The central melanocortin system plays a critical role in controlling body weight balance. Melanocortin neurons sense and integrate the neuronal and hormonal signals, and then send regulatory projections, releasing anorexigenic or orexigenic melanocortin neuropeptides, to downstream neurons to regulate the food intake and energy expenditure. This review summarizes the latest progress in our understanding of the role of the melanocortin pathway in energy homeostasis. We also review the advances in the identification of human genetic variants that cause obesity via mechanisms that affect the central melanocortin system, which have provided rational targets for treatment of genetically susceptible patients.
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Affiliation(s)
- Yongjie Yang
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Yong Xu
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA.,Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
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16
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Chen V, Bruno AE, Britt LL, Hernandez CC, Gimenez LE, Peisley A, Cone RD, Millhauser GL. Membrane orientation and oligomerization of the melanocortin receptor accessory protein 2. J Biol Chem 2020; 295:16370-16379. [PMID: 32943551 DOI: 10.1074/jbc.ra120.015482] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 09/08/2020] [Indexed: 12/12/2022] Open
Abstract
The melanocortin receptor accessory protein 2 (MRAP2) plays a pivotal role in the regulation of several G protein-coupled receptors that are essential for energy balance and food intake. MRAP2 loss-of-function results in obesity in mammals. MRAP2 and its homolog MRAP1 have an unusual membrane topology and are the only known eukaryotic proteins that thread into the membrane in both orientations. In this study, we demonstrate that the conserved polybasic motif that dictates the membrane topology and dimerization of MRAP1 does not control the membrane orientation and dimerization of MRAP2. We also show that MRAP2 dimerizes through its transmembrane domain and can form higher-order oligomers that arrange MRAP2 monomers in a parallel orientation. Investigating the molecular details of MRAP2 structure is essential for understanding the mechanism by which it regulates G protein-coupled receptors and will aid in elucidating the pathways involved in metabolic dysfunction.
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Affiliation(s)
- Valerie Chen
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California, USA
| | - Antonio E Bruno
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California, USA
| | - Laura L Britt
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California, USA
| | - Ciria C Hernandez
- Life Sciences Institute and Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Luis E Gimenez
- Life Sciences Institute and Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Alys Peisley
- Life Sciences Institute and Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Roger D Cone
- Life Sciences Institute and Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Glenn L Millhauser
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California, USA.
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17
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Structural Complexity and Plasticity of Signaling Regulation at the Melanocortin-4 Receptor. Int J Mol Sci 2020; 21:ijms21165728. [PMID: 32785054 PMCID: PMC7460885 DOI: 10.3390/ijms21165728] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 08/03/2020] [Accepted: 08/06/2020] [Indexed: 02/06/2023] Open
Abstract
The melanocortin-4 receptor (MC4R) is a class A G protein-coupled receptor (GPCR), essential for regulation of appetite and metabolism. Pathogenic inactivating MC4R mutations are the most frequent cause of monogenic obesity, a growing medical and socioeconomic problem worldwide. The MC4R mediates either ligand-independent or ligand-dependent signaling. Agonists such as α-melanocyte-stimulating hormone (α-MSH) induce anorexigenic effects, in contrast to the endogenous inverse agonist agouti-related peptide (AgRP), which causes orexigenic effects by suppressing high basal signaling activity. Agonist action triggers the binding of different subtypes of G proteins and arrestins, leading to concomitant induction of diverse intracellular signaling cascades. An increasing number of experimental studies have unraveled molecular properties and mechanisms of MC4R signal transduction related to physiological and pathophysiological aspects. In addition, the MC4R crystal structure was recently determined at 2.75 Å resolution in an inactive state bound with a peptide antagonist. Underpinned by structural homology models of MC4R complexes simulating a presumably active-state conformation compared to the structure of the inactive state, we here briefly summarize the current understanding and key players involved in the MC4R switching process between different activity states. Finally, these perspectives highlight the complexity and plasticity in MC4R signaling regulation and identify gaps in our current knowledge.
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18
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Tao YX. Molecular chaperones and G protein-coupled receptor maturation and pharmacology. Mol Cell Endocrinol 2020; 511:110862. [PMID: 32389798 DOI: 10.1016/j.mce.2020.110862] [Citation(s) in RCA: 13] [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] [Received: 09/15/2019] [Revised: 05/04/2020] [Accepted: 05/05/2020] [Indexed: 12/15/2022]
Abstract
G protein-coupled receptors (GPCRs) are highly conserved versatile signaling molecules located at the plasma membrane that respond to diverse extracellular signals. They regulate almost all physiological processes in the vertebrates. About 35% of current drugs target these receptors. Mutations in these genes have been identified as causes of numerous diseases. The seven transmembrane domain structure of GPCRs implies that the folding of these transmembrane proteins is extremely complicated and difficult. Indeed, many wild type GPCRs are not folded optimally. The most common defect in genetic diseases caused by GPCR mutations is misfolding and failure to reach the plasma membrane where it functions. General molecular chaperones aid the folding of all proteins, including GPCRs, by preventing aggregation, promoting folding and disaggregating small aggregates. Some GPCRs need additional receptor-specific chaperones to assist their folding. Many of these receptor-specific chaperones interact with additional receptors and alter receptor pharmacology, expanding the understanding of these chaperone proteins.
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Affiliation(s)
- Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, 36849-5519, USA.
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19
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Differential Signaling Profiles of MC4R Mutations with Three Different Ligands. Int J Mol Sci 2020; 21:ijms21041224. [PMID: 32059383 PMCID: PMC7072973 DOI: 10.3390/ijms21041224] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 02/06/2020] [Accepted: 02/06/2020] [Indexed: 12/21/2022] Open
Abstract
The melanocortin 4 receptor (MC4R) is a key player in hypothalamic weight regulation and energy expenditure as part of the leptin–melanocortin pathway. Mutations in this G protein coupled receptor (GPCR) are the most common cause for monogenetic obesity, which appears to be mediated by changes in the anorectic action of MC4R via GS-dependent cyclic adenosine-monophosphate (cAMP) signaling as well as other signaling pathways. To study potential bias in the effects of MC4R mutations between the different signaling pathways, we investigated three major MC4R mutations: a GS loss-of-function (S127L) and a GS gain-of-function mutant (H158R), as well as the most common European single nucleotide polymorphism (V103I). We tested signaling of all four major G protein families plus extracellular regulated kinase (ERK) phosphorylation and β-arrestin2 recruitment, using the two endogenous agonists, α- and β-melanocyte stimulating hormone (MSH), along with a synthetic peptide agonist (NDP-α-MSH). The S127L mutation led to a full loss-of-function in all investigated pathways, whereas V103I and H158R were clearly biased towards the Gq/11 pathway when challenged with the endogenous ligands. These results show that MC4R mutations can cause vastly different changes in the various MC4R signaling pathways and highlight the importance of a comprehensive characterization of receptor mutations.
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20
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Tao M, Ji RL, Huang L, Fan SY, Liu T, Liu SJ, Tao YX. Regulation of Melanocortin-4 Receptor Pharmacology by Two Isoforms of Melanocortin Receptor Accessory Protein 2 in Topmouth Culter ( Culter alburnus). Front Endocrinol (Lausanne) 2020; 11:538. [PMID: 32922362 PMCID: PMC7456811 DOI: 10.3389/fendo.2020.00538] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 07/02/2020] [Indexed: 01/03/2023] Open
Abstract
Melanocortin-4 receptor (MC4R) plays important roles in regulation of multiple physiological processes, and interaction of MC4R and melanocortin receptor accessory protein 2 (MRAP2) is suggested to play pivotal role in energy balance of vertebrates. Topmouth culter (Culter alburnus) is an economically important freshwater fish in China. Herein we cloned culter mc4r, mrap2a, and mrap2b. Culter mc4r consisted of a 981 bp open reading frame encoding a protein of 326 amino acids. qRT-PCR revealed that mc4r, mrap2a, and mrap2b were primarily expressed in the central nervous system. In the periphery, mc4r and mrap2b were expressed more widely in the male, while mrap2a was expressed more widely in the female. Culter MC4R could bind to four peptide agonists and increase intracellular cAMP production dose dependently. Culter MC4R was constitutively active in both cAMP and ERK1/2 pathways, which was differentially regulated by culter MRAP2a and MRAP2b. Culter MRAP2a significantly increased Bmax and decreased agonist-stimulated cAMP, while MRAP2b increased cell surface and total expression but did not affect Bmax and agonist-stimulated cAMP. These results will aid the investigation of the potential physiological processes that MC4R might be involved in topmouth culter.
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Affiliation(s)
- Min Tao
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, China
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
| | - Ren-Lei Ji
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
| | - Lu Huang
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Si-Yu Fan
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Ting Liu
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
| | - Shao-Jun Liu
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, China
- *Correspondence: Shao-Jun Liu
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
- Ya-Xiong Tao
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21
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Baron M, Maillet J, Huyvaert M, Dechaume A, Boutry R, Loiselle H, Durand E, Toussaint B, Vaillant E, Philippe J, Thomas J, Ghulam A, Franc S, Charpentier G, Borys JM, Lévy-Marchal C, Tauber M, Scharfmann R, Weill J, Aubert C, Kerr-Conte J, Pattou F, Roussel R, Balkau B, Marre M, Boissel M, Derhourhi M, Gaget S, Canouil M, Froguel P, Bonnefond A. Loss-of-function mutations in MRAP2 are pathogenic in hyperphagic obesity with hyperglycemia and hypertension. Nat Med 2019; 25:1733-1738. [PMID: 31700171 PMCID: PMC6858878 DOI: 10.1038/s41591-019-0622-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Accepted: 09/25/2019] [Indexed: 12/31/2022]
Abstract
The G-protein-coupled receptor (GPCR) accessory protein MRAP2 is implicated in energy control in rodents, notably via melanocortin-4 receptor (MC4R)1. Although some MRAP2 mutations have been described in people with obesity1–3, their functional consequences on adiposity remain elusive. Using large-scale sequencing of MRAP2 in 9,418 people, we identified 23 rare heterozygous variants associated with increased obesity risk in both adults and children. Functional assessment of each variant shows that loss-of-function MRAP2 variants are pathogenic for monogenic hyperphagic obesity, with hyperglycemia and hypertension. This contrasts with other monogenic forms of obesity characterized by excessive hunger, including MC4R deficiency, that present with low blood pressure and normal glucose tolerance4. The pleiotropic metabolic effect of loss-of-function mutations in MRAP2 might be due to the failure of different MRAP2-regulated GPCRs in various tissues including pancreatic islets.
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Affiliation(s)
- Morgane Baron
- CNRS UMR 8199, European Genomic Institute for Diabetes, Institut Pasteur de Lille, University of Lille, Lille, France
| | - Julie Maillet
- CNRS UMR 8199, European Genomic Institute for Diabetes, Institut Pasteur de Lille, University of Lille, Lille, France
| | - Marlène Huyvaert
- CNRS UMR 8199, European Genomic Institute for Diabetes, Institut Pasteur de Lille, University of Lille, Lille, France
| | - Aurélie Dechaume
- CNRS UMR 8199, European Genomic Institute for Diabetes, Institut Pasteur de Lille, University of Lille, Lille, France
| | - Raphaël Boutry
- CNRS UMR 8199, European Genomic Institute for Diabetes, Institut Pasteur de Lille, University of Lille, Lille, France
| | - Hélène Loiselle
- CNRS UMR 8199, European Genomic Institute for Diabetes, Institut Pasteur de Lille, University of Lille, Lille, France
| | - Emmanuelle Durand
- CNRS UMR 8199, European Genomic Institute for Diabetes, Institut Pasteur de Lille, University of Lille, Lille, France
| | - Bénédicte Toussaint
- CNRS UMR 8199, European Genomic Institute for Diabetes, Institut Pasteur de Lille, University of Lille, Lille, France
| | - Emmanuel Vaillant
- CNRS UMR 8199, European Genomic Institute for Diabetes, Institut Pasteur de Lille, University of Lille, Lille, France
| | - Julien Philippe
- CNRS UMR 8199, European Genomic Institute for Diabetes, Institut Pasteur de Lille, University of Lille, Lille, France.,Center for Human Disease Modeling, Duke University Medical Center, Durham, NC, USA
| | - Jérémy Thomas
- Laboratoire de Biochimie et Hormonologie, Centre de Biologie Pathologie, Centre Hospitalier Régional Universitaire, Lille, France
| | - Amjad Ghulam
- Laboratoire de Biochimie et Hormonologie, Centre de Biologie Pathologie, Centre Hospitalier Régional Universitaire, Lille, France
| | - Sylvia Franc
- CERITD (Centre d'Étude et de Recherche pour l'Intensification du Traitement du Diabète), Evry, France.,Department of Diabetes, Sud-Francilien Hospital, University Paris-Sud, Orsay, Corbeil-Essonnes, France
| | - Guillaume Charpentier
- CERITD (Centre d'Étude et de Recherche pour l'Intensification du Traitement du Diabète), Evry, France.,Department of Diabetes, Sud-Francilien Hospital, University Paris-Sud, Orsay, Corbeil-Essonnes, France
| | | | - Claire Lévy-Marchal
- Department of Clinical Epidemiology, Inserm CIE 05, Robert Debré Hospital, Paris, France
| | - Maïthé Tauber
- Endocrinology, Obesity, Bone Disease, Genetics and Medical Gynecology, Hôpital des Enfants, Inserm UMR 1043, Université Toulouse III-Paul Sabatier, Toulouse, France
| | - Raphaël Scharfmann
- Inserm U1016, Institut Cochin, Université Paris Descartes, Paris, France
| | - Jacques Weill
- Pediatric Endocrine Department, Lille Hospital, Lille, France
| | | | - Julie Kerr-Conte
- Inserm U1190, EGID, CHU Lille, University of Lille, Lille, France
| | - François Pattou
- Inserm U1190, EGID, CHU Lille, University of Lille, Lille, France
| | - Ronan Roussel
- Department of Diabetology, Endocrinology and Nutrition, Hôpital Bichat, DHU FIRE, Assistance Publique Hôpitaux de Paris, Paris, France.,Inserm U1138, Centre de Recherche des Cordeliers, Paris, France.,UFR de Médecine, University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Beverley Balkau
- Inserm U1018, Center for Research in Epidemiology and Population Health, Villejuif, France.,University Paris-Saclay, University Paris-Sud, Villejuif, France
| | - Michel Marre
- Inserm U1138, Centre de Recherche des Cordeliers, Paris, France.,CMC Ambroise Paré, Neuilly-sur-Seine, France
| | - Mathilde Boissel
- CNRS UMR 8199, European Genomic Institute for Diabetes, Institut Pasteur de Lille, University of Lille, Lille, France
| | - Mehdi Derhourhi
- CNRS UMR 8199, European Genomic Institute for Diabetes, Institut Pasteur de Lille, University of Lille, Lille, France
| | - Stefan Gaget
- CNRS UMR 8199, European Genomic Institute for Diabetes, Institut Pasteur de Lille, University of Lille, Lille, France
| | - Mickaël Canouil
- CNRS UMR 8199, European Genomic Institute for Diabetes, Institut Pasteur de Lille, University of Lille, Lille, France
| | - Philippe Froguel
- CNRS UMR 8199, European Genomic Institute for Diabetes, Institut Pasteur de Lille, University of Lille, Lille, France. .,Department of Metabolism, Section of Genomics of Common Disease, Imperial College London, London, UK.
| | - Amélie Bonnefond
- CNRS UMR 8199, European Genomic Institute for Diabetes, Institut Pasteur de Lille, University of Lille, Lille, France. .,Department of Metabolism, Section of Genomics of Common Disease, Imperial College London, London, UK.
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22
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Wang M, Chen Y, Zhu M, Xu B, Guo W, Lyu Y, Zhang C. Pharmacological modulation of melanocortin-4 receptor by melanocortin receptor accessory protein 2 in Nile tilapia. Gen Comp Endocrinol 2019; 282:113219. [PMID: 31299224 DOI: 10.1016/j.ygcen.2019.113219] [Citation(s) in RCA: 18] [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: 11/10/2018] [Revised: 05/19/2019] [Accepted: 07/08/2019] [Indexed: 11/19/2022]
Abstract
The melanocortin-4 receptor (MC4R) acts as a member of G-protein coupled receptors and participate in food intake and energy expenditure. Melanocortin 2 receptor accessory protein 2 (MRAP2) plays a critical role in regulating MC4R signaling in mammals and zebrafish. However, evidence on their interaction in other teleost species remains elusive. Here, we cloned and assessed the evolutionary aspect and pharmacological modulation of MRAP2 on MC4R signaling in Nile tilapia (Oreochromis niloticus). Tissue distribution analysis of tmc4r and tmrap2 confirmed their co-expression in the brain region. tMRAP2 protein could form antiparallel homo-dimer and directly interacted with tMC4R in vitro and presence of tMRAP2 led to the reduction of agonist response and surface expression of tMC4R. Overall, our findings provide a comparative overview on the evolutionary conservation, genomic distribution, tissue-specific expression and pharmacological profile of the MC4R and MRAP2 in another non-mammalian teleost.
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Affiliation(s)
- Meng Wang
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Yijun Chen
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Ming Zhu
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Bingxin Xu
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Wenxuan Guo
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Yunsong Lyu
- Beijing No. 12 High School, No. 15 Yize Road, Beijing, China
| | - Chao Zhang
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China.
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Yang LK, Zhang ZR, Wen HS, Tao YX. Characterization of channel catfish (Ictalurus punctatus) melanocortin-3 receptor reveals a potential network in regulation of energy homeostasis. Gen Comp Endocrinol 2019; 277:90-103. [PMID: 30905760 DOI: 10.1016/j.ygcen.2019.03.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 03/12/2019] [Accepted: 03/18/2019] [Indexed: 11/19/2022]
Abstract
The melanocortin-3 receptor (MC3R) is known to be involved in regulation of energy homeostasis, regulating feed efficiency and nutrient partitioning in mammals. Its physiological roles in non-mammalian vertebrates, especially economically important aquaculture species, are not well understood. Channel catfish (Ictalurus punctatus) is the main freshwater aquaculture species in North America. In this study, we characterized the channel catfish MC3R. The mc3r of channel catfish encoded a putative protein (ipMC3R) of 367 amino acids. We transfected HEK293T cells with ipMC3R plasmid for functional studies. Five agonists, including adrenocorticotropin, α-melanocyte stimulating hormone (α-MSH), β-MSH, [Nle4, D-Phe7]-α-MSH, and D-Trp8-γ-MSH, were used in the pharmacological studies. Our results showed that ipMC3R bound β-MSH with higher affinity and D-Trp8-γ-MSH with lower affinity compared with human MC3R. All agonists could stimulate ipMC3R and increase intracellular cAMP production with sub-nanomolar potencies. The extracellular signal-regulated kinases 1 and 2 (ERK1/2) activation could also be triggered by ipMC3R. The ipMC3R exhibited constitutive activities in both cAMP and ERK1/2 pathways, and Agouti-related protein served as an inverse agonist at ipMC3R, potently inhibiting the high basal cAMP level. Moreover, we showed that melanocortin receptor accessory protein 2 (MRAP2) preferentially modulated ipMC3R in cAMP production rather than ERK1/2 activation. Our study will assist further investigation of the physiological roles of the ipMC3R, especially in energy homeostasis, in channel catfish.
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Affiliation(s)
- Li-Kun Yang
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States
| | - Zheng-Rui Zhang
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States; Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Hai-Shen Wen
- College of Fisheries, Ocean University of China, Qingdao, China
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States.
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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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Bruschetta G, Kim JD, Diano S, Chan LF. Overexpression of melanocortin 2 receptor accessory protein 2 (MRAP2) in adult paraventricular MC4R neurons regulates energy intake and expenditure. Mol Metab 2018; 18:79-87. [PMID: 30352741 PMCID: PMC6308034 DOI: 10.1016/j.molmet.2018.09.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 09/18/2018] [Accepted: 09/30/2018] [Indexed: 11/18/2022] Open
Abstract
Objective Melanocortin 2 receptor accessory protein 2 (MRAP2) has a critical role in energy homeostasis. Although MRAP2 has been shown to regulates a number of GPCRs involved in metabolism, the key neurons responsible for the phenotype of gross obesity in MRAP2 deficient animals are unclear. Furthermore, to date, all the murine MRAP2 models involve the prenatal deletion of MRAP2. Methods To target Melanocortin 4 receptor (MC4R)-expressing neurons in the hypothalamic paraventricular nucleus (PVN), we performed stereotaxic surgery using AAV to selectively overexpress MRAP2 postnatally in adult Mc4r-cre mice. We assessed energy homeostasis, glucose metabolism, core body temperature, and response to MC3R/MC4R agonist MTII. Results Mc4r-crePVN-MRAP2 female mice on a standard chow diet had less age-related weight gain and improved glucose/insulin profile compared to control Mc4r-crePVN-GFP mice. These changes were associated with a reduction in food intake and increased energy expenditure. In contrast, Mc4r-crePVN-MRAP2 male mice showed no improvement on a chow diet, but improvement of energy and glucose metabolism was observed following high fat diet (HFD) feeding. In addition, an increase in core body temperature was found in both females fed on standard chow diet and males fed on HFD. Mc4r-crePVN-MRAP2 female and male mice showed increased neuronal activation in the PVN compared to controls, with further increase in neuronal activation post MTII treatment in females. Conclusions Our data indicate a site-specific role for MRAP2 in PVN MC4R-expressing neurons in potentiating MC4R neuronal activation at baseline conditions in the regulation of food intake and energy expenditure. Postnatal overexpression of MRAP2 regulates energy balance, thermogenesis and glucose metabolism. Overexpression of MRAP2 in MC4R expressing neurons increases PVN neuronal activation. There is a sex difference in extent of metabolic protection, with a more marked lean phenotype in females.
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Affiliation(s)
- Giuseppe Bruschetta
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine, New Haven, CT, 06520, USA; Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - Jung Dae Kim
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine, New Haven, CT, 06520, USA; Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - Sabrina Diano
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine, New Haven, CT, 06520, USA; Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale University School of Medicine, New Haven, CT, 06520, USA; Department of Neuroscience, Yale University School of Medicine, New Haven, CT, 06520, USA; Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT, 06520, USA; Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, Italy.
| | - Li F Chan
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK.
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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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Liang J, Li L, Jin X, Xu B, Pi L, Liu S, Zhu W, Zhang C, Luan B, Gong L, Zhang C. Pharmacological effect of human melanocortin-2 receptor accessory protein 2 variants on hypothalamic melanocortin receptors. Endocrine 2018; 61:94-104. [PMID: 29704154 DOI: 10.1007/s12020-018-1596-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 04/09/2018] [Indexed: 10/17/2022]
Abstract
PURPOSE Melanocortin-3 receptor (MC3R), melanocortin-4 receptor (MC4R), and a recently identified melanocortin-2 receptor accessory protein 2 (MRAP2), are highly expressed in hypothalamus and coordinately regulate energy homeostasis, but the single cellular transcriptome of melanocortin system remains unknown. Several infrequent MRAP2 variants are reported from severe obese human patients but the mechanisms on how they affect melanocortin signaling are unclear. METHODS First, we performed in silico analysis of mouse hypothalamus RNA sequencing datasets at single-cell resolution from two independent studies. Next, we inspected the three-dimensional conformational alteration of three mutations on MRAP2 protein. Finally, the influence of MRAP2 variants on MC3R and MC4R signaling was analyzed in vitro. RESULTS (1) We confirmed the actual co-expression of Mrap2 with Mc3r and Mc4r, and demonstrated more broad distribution of Mrap2-positive neuronal populations than Mc3r or Mc4r in mouse hypothalamus. (2) Compared with wild-type MRAP2, MRAP2N88Y, and MRAP2R125C showed impaired α-MSH-induced MC4R or MC3R stimulation. (3) MRAP2N88Yexhibited enhanced interaction with MC4R protein and its own. CONCLUSIONS This is the first dedicated description of single-cell transcriptome signature of Mrap2, Mc3r, and Mc4r in the central nerve system and the first evidence describing the unique dimer formation, conformational change, and pharmacological effect of MRAP2 mutations on MC3R signaling.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Animals
- Carrier Proteins/pharmacology
- Computer Simulation
- Genetic Variation
- Humans
- Hypothalamus/drug effects
- Hypothalamus/metabolism
- Mice
- Mutation/genetics
- Neurons/metabolism
- Nucleic Acid Conformation
- Plasmids
- RNA/genetics
- Receptor, Melanocortin, Type 3/genetics
- Receptor, Melanocortin, Type 3/metabolism
- Receptor, Melanocortin, Type 4/genetics
- Receptor, Melanocortin, Type 4/metabolism
- Receptors, Melanocortin/drug effects
- Signal Transduction/genetics
- alpha-MSH/pharmacology
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Affiliation(s)
- Jinye Liang
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Lei Li
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Xuanxuan Jin
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Bingxin Xu
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Linyu Pi
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Shangyun Liu
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Wei Zhu
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Cong Zhang
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Bing Luan
- Department of Endocrinology, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Lulu Gong
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China.
| | - Chao Zhang
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China.
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Habara M, Mori N, Okada Y, Kawasumi K, Nakao N, Tanaka Y, Arai T, Yamamoto I. Molecular characterization of feline melanocortin 4 receptor and melanocortin 2 receptor accessory protein 2. Gen Comp Endocrinol 2018; 261:31-39. [PMID: 29360464 DOI: 10.1016/j.ygcen.2018.01.020] [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: 11/15/2017] [Revised: 01/17/2018] [Accepted: 01/17/2018] [Indexed: 01/06/2023]
Abstract
Melanocortin 4 receptor (MC4R), which is a member of the G protein-coupled receptor (GPCR) family, mediates regulation of energy homeostasis upon the binding of α-melanocyte-stimulating hormone (α-MSH) in the central nervous system (CNS). Melanocortin 2 receptor accessory protein 2 (MRAP2) modulates the function of MC4R. We performed cDNA cloning of cat MC4R and MRAP2 and characterized their amino acid sequences, mRNA expression patterns in cat tissues, protein-protein interactions, and functions. We found high sequence homology (>88%) with other mammalian MC4R and MRAP2 encoding 332 and 206 amino acid residues, respectively. Reverse transcription-polymerase chain reaction analysis revealed that cat MC4R and MRAP2 mRNA were expressed highly in the CNS. In CHO-K1 cells transfected with cat MC4R, stimulation with α-MSH increased intracellular cyclic adenosine monophosphate (cAMP) concentration in a dose-dependent manner. Furthermore, the presence of MRAP2 enhanced the cat MC4R-mediated cAMP production. These results suggested that cat MC4R acts as a neuronal mediator in the CNS and that its function is modulated by MRAP2. In addition, our NanoBiT study showed the dynamics of their interactions in living cells; stimulation with α-MSH slightly affected the interaction between MC4R and MRAP2, and did not affect MC4R homodimerization, suggesting that they interact in the basal state and that structural change of MC4R by activation may affect the interaction between MC4R and MRAP2.
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Affiliation(s)
- Makoto Habara
- Department of Basic Veterinary Medicine, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino-shi, Tokyo 1808602, Japan
| | - Nobuko Mori
- Department of Basic Veterinary Medicine, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino-shi, Tokyo 1808602, Japan; Laboratory of Molecular Biomedicine for Pathogenesis, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 1130033, Japan
| | - Yuki Okada
- Department of Basic Veterinary Medicine, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino-shi, Tokyo 1808602, Japan
| | - Koh Kawasumi
- Department of Basic Veterinary Medicine, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino-shi, Tokyo 1808602, Japan
| | - Nobuhiro Nakao
- Laboratory of Animal Physiology, Department of Animal Science, Faculty of Applied Life Science, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino-shi, Tokyo 1808602, Japan
| | - Yoshikazu Tanaka
- Department of Veterinary Hygiene, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino-shi, Tokyo 1808602, Japan
| | - Toshiro Arai
- Department of Basic Veterinary Medicine, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino-shi, Tokyo 1808602, Japan
| | - Ichiro Yamamoto
- Department of Basic Veterinary Medicine, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino-shi, Tokyo 1808602, Japan.
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Abstract
Zusammenfassung
Autosomal-rezessiv vererbte Mutationen in den Genen für Leptin, Leptinrezeptor, Proopiomelanocortin (POMC) und Prohormon-Convertase (PC1) führen zu einer ausgeprägten frühkindlichen Adipositas. Patienten mit biologisch inaktivem Leptin oder Leptinmangel können mit humanem rekombinanten Leptin erfolgreich behandelt werden. Für die anderen Patienten hat sich die Behandlung mit einem α‑MSH-Analogon als erfolgreich erwiesen (POMC-Patienten) bzw. befindet sich derzeit in Erprobung.
Kodominant vererbte Mutationen im MC4R-Gen stellen die häufigste Form der monogenen Adipositas dar. Eine kausale Therapie ist hier allerdings nicht möglich.
Es sind inzwischen noch weitere, autosomal-rezessiv vererbte Genmutationen identifiziert worden, die ebenfalls mit einer ausgeprägten Adipositas assoziiert sind. Die meisten dieser Mutationen liegen in Genen, die in die Signaltransduktion von MC4R oder dem Leptinrezeptor involviert sind. Auch für diese Patienten gibt es aktuell noch keine kausale Therapie.
Schlussfolgerung: Bei Patienten mit extremer frühkindlicher Adipositas sollte eine molekulargenetische Diagnostik eingeleitet werden, da die Diagnosestellung für die Betroffenen und ihre Familie eine enorme Erleichterung bedeuten kann. Außerdem gewinnen die Familien Klarheit über das Wiederholungsrisiko und eventuell ist sogar eine kausale oder zumindest optimierte Therapie möglich.
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Affiliation(s)
- Julia von Schnurbein
- Aff1 grid.410712.1 Klinik für Kinder- und Jugendmedizin, Zentrum für Seltene Erkrankungen (ZSE) Ulm, Sektion Pädiatrische Endokrinologie und Diabetologie Universitätsklinik für Kinder- und Jugendmedizin Eythstr. 24 89075 Ulm Deutschland
| | - Martin Wabitsch
- Aff1 grid.410712.1 Klinik für Kinder- und Jugendmedizin, Zentrum für Seltene Erkrankungen (ZSE) Ulm, Sektion Pädiatrische Endokrinologie und Diabetologie Universitätsklinik für Kinder- und Jugendmedizin Eythstr. 24 89075 Ulm Deutschland
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da Fonseca ACP, Mastronardi C, Johar A, Arcos-Burgos M, Paz-Filho G. Genetics of non-syndromic childhood obesity and the use of high-throughput DNA sequencing technologies. J Diabetes Complications 2017; 31:1549-1561. [PMID: 28735903 DOI: 10.1016/j.jdiacomp.2017.04.026] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 04/18/2017] [Accepted: 04/19/2017] [Indexed: 12/12/2022]
Abstract
BACKGROUND Childhood obesity is a serious public health problem associated with the development of several chronic diseases, such as type 2 diabetes mellitus, dyslipidemia, and hypertension. The elevated prevalence of obesity is mostly due to inadequate diet and lifestyle, but it is also influenced by genetic factors. OBJECTIVES To review recent advances in the field of the genetics of obesity. We summarize the list of genes associated with the rare non-syndromic forms of obesity, and explain their function. Furthermore, we discuss the technologies that are available for the genetic diagnosis of obesity. RESULTS Several studies reported that single gene variants cause Mendelian forms of obesity, determined by mutations of major effect in single genes. Rare, non-syndromic forms of obesity are a result of loss-of-function mutations in genes that act on the development and function of the hypothalamus or the leptin-melanocortin pathway. These variants disrupt enzymes and receptors that play a role in energy homeostasis, resulting in severe early-onset obesity and endocrine dysfunctions. Different approaches and technologies have been used to understand the genetic background of obesity. Currently, whole genome and whole exome sequencing are important diagnostic tools to identify new genes and variants associated with severe obesity, but other approaches are also useful at individual or population levels, such as linkage analysis, candidate gene sequencing, chromosomal microarray analysis, and genome-wide association studies. CONCLUSIONS The understanding of the genetic causes of obesity and the usefulness and limitations of the genetic diagnostic approaches can contribute to the development of new personalized therapeutic targets against obesity.
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Affiliation(s)
| | - Claudio Mastronardi
- Institute of Translational Medicine, Universidad del Rosario, Bogota, Colombia
| | - Angad Johar
- Department of Genome Sciences, John Curtin School of Medical Research, The Australian National University, Australia.
| | | | - Gilberto Paz-Filho
- Department of Genome Sciences, John Curtin School of Medical Research, The Australian National University, Australia.
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Evaluation of a melanocortin-4 receptor (MC4R) agonist (Setmelanotide) in MC4R deficiency. Mol Metab 2017; 6:1321-1329. [PMID: 29031731 PMCID: PMC5641599 DOI: 10.1016/j.molmet.2017.06.015] [Citation(s) in RCA: 178] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 06/26/2017] [Accepted: 06/28/2017] [Indexed: 01/08/2023] Open
Abstract
Objective Pro-opiomelanocortin (POMC)-derived peptides act on neurons expressing the Melanocortin 4 receptor (MC4R) to reduce body weight. Setmelanotide is a highly potent MC4R agonist that leads to weight loss in diet-induced obese animals and in obese individuals with complete POMC deficiency. While POMC deficiency is very rare, 1–5% of severely obese individuals harbor heterozygous mutations in MC4R. We sought to assess the efficacy of Setmelanotide in human MC4R deficiency. Methods We studied the effects of Setmelanotide on mutant MC4Rs in cells and the weight loss response to Setmelanotide administration in rodent studies and a human clinical trial. We annotated the functional status of 369 published MC4R variants. Results In cells, we showed that Setmelanotide is significantly more potent at MC4R than the endogenous ligand alpha-melanocyte stimulating hormone and can disproportionally rescue signaling by a subset of severely impaired MC4R mutants. Wild-type rodents appear more sensitive to Setmelanotide when compared to MC4R heterozygous deficient mice, while MC4R knockout mice fail to respond. In a 28-day Phase 1b clinical trial, Setmelanotide led to weight loss in obese MC4R variant carriers. Patients with POMC defects upstream of MC4R show significantly more weight loss with Setmelanotide than MC4R deficient patients or obese controls. Conclusions Setmelanotide led to weight loss in obese people with MC4R deficiency; however, further studies are justified to establish whether Setmelanotide can elicit clinically meaningful weight loss in a subset of the MC4R deficient obese population.
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Rouault AAJ, Srinivasan DK, Yin TC, Lee AA, Sebag JA. Melanocortin Receptor Accessory Proteins (MRAPs): Functions in the melanocortin system and beyond. Biochim Biophys Acta Mol Basis Dis 2017; 1863:2462-2467. [PMID: 28499989 DOI: 10.1016/j.bbadis.2017.05.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 05/02/2017] [Accepted: 05/05/2017] [Indexed: 12/27/2022]
Abstract
G-protein coupled receptors (GPCRs) are regulated by numerous proteins including kinases, G-proteins, β-arrestins and accessory proteins. Several families of GPCR accessory proteins like Receptor Activity Modifying Proteins, Receptor Transporting Proteins and Melanocortin Receptor Accessory Proteins (MRAPs) have been identified as regulator of receptor trafficking, signaling and ligand specificity. The MRAP family contains two members, MRAP1 and MRAP2, responsible for the formation of a functional ACTH receptor and for the regulation of energy homeostasis respectively. Like all known GPCR accessory proteins, MRAPs are single transmembrane proteins, however, they form a unique structure since they assemble as an anti-parallel homodimer. Moreover, the accepted idea that MRAPs are specific regulators of melanocortin receptors was recently challenged by the discovery that MRAP2 inhibits the activity of prokineticin receptors. Recent studies are starting to explain the role of the unusual structure of MRAPs and to illustrate the importance of MRAP2 for the maintenance of both energy and glucose homeostasis. This article is part of a Special Issue entitled: Melanocortin Receptors - edited by Ya-Xiong Tao.
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Affiliation(s)
- Alix A J Rouault
- University of Iowa, Carver College of Medicine, Department of Molecular Physiology and Biophysics, Fraternal Order of Eagle Diabetes Research Center, Iowa City, IA 52242, United States
| | - Dinesh K Srinivasan
- University of Iowa, Carver College of Medicine, Department of Molecular Physiology and Biophysics, Fraternal Order of Eagle Diabetes Research Center, Iowa City, IA 52242, United States
| | - Terry C Yin
- University of Iowa, Carver College of Medicine, Department of Molecular Physiology and Biophysics, Fraternal Order of Eagle Diabetes Research Center, Iowa City, IA 52242, United States
| | - Abigail A Lee
- University of Iowa, Carver College of Medicine, Department of Molecular Physiology and Biophysics, Fraternal Order of Eagle Diabetes Research Center, Iowa City, IA 52242, United States
| | - Julien A Sebag
- University of Iowa, Carver College of Medicine, Department of Molecular Physiology and Biophysics, Fraternal Order of Eagle Diabetes Research Center, Iowa City, IA 52242, United States.
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