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Rodríguez Rondón AV, Welling MS, van den Akker ELT, van Rossum EFC, Boon EMJ, van Haelst MM, Delhanty PJD, Visser JA. MC4R Variants Modulate α-MSH and Setmelanotide Induced Cellular Signaling at Multiple Levels. J Clin Endocrinol Metab 2024; 109:2452-2466. [PMID: 38567654 PMCID: PMC11403317 DOI: 10.1210/clinem/dgae210] [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: 12/05/2023] [Revised: 02/10/2024] [Indexed: 04/04/2024]
Abstract
CONTEXT The melanocortin-4 receptor (MC4R) plays an important role in body weight regulation. Pathogenic MC4R variants are the most common cause of monogenic obesity. OBJECTIVE We have identified 17 MC4R variants in adult and pediatric patients with obesity. Here we aimed to functionally characterize these variants by analyzing 4 different aspects of MC4R signaling. In addition, we aimed to analyze the effect of setmelanotide, a potent MC4R agonist, on these MC4R variants. MATERIALS AND METHODS Cell surface expression and α-melanocyte stimulating hormone (α-MSH)- or setmelanotide-induced cAMP response, β-arrestin-2 recruitment, and ERK activation were measured in cells expressing either wild type or variant MC4R. RESULTS We found a large heterogeneity in the function of these variants. We identified variants with a loss of response for all studied MC4R signaling, variants with no cAMP accumulation or ERK activation but normal β-arrestin-2 recruitment, and variants with normal cAMP accumulation and ERK activation but decreased β-arrestin-2 recruitment, indicating disrupted desensitization and signaling mechanisms. Setmelanotide displayed a greater potency and similar efficacy as α-MSH and induced significantly increased maximal cAMP responses of several variants compared to α-MSH. Despite the heterogeneity in functional response, there was no apparent difference in the obesity phenotype in our patients. CONCLUSION We show that these obesity-associated MC4R variants affect MC4R signaling differently yet lead to a comparable clinical phenotype. Our results demonstrate the clinical importance of assessing the effect of MC4R variants on a range of molecular signaling mechanisms to determine their association with obesity, which may aid in improving personalized treatment.
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Affiliation(s)
- Alejandra V Rodríguez Rondón
- Obesity Center CGG and Expertise Center Genetic Obesity, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, The Netherlands
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, The Netherlands
| | - Mila S Welling
- Obesity Center CGG and Expertise Center Genetic Obesity, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, The Netherlands
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, The Netherlands
- Department of Pediatrics, Division of Endocrinology, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, 3015 GD Rotterdam, The Netherlands
| | - Erica L T van den Akker
- Obesity Center CGG and Expertise Center Genetic Obesity, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, The Netherlands
- Department of Pediatrics, Division of Endocrinology, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, 3015 GD Rotterdam, The Netherlands
| | - Elisabeth F C van Rossum
- Obesity Center CGG and Expertise Center Genetic Obesity, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, The Netherlands
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, The Netherlands
| | - Elles M J Boon
- Department of Human Genetics, Amsterdam University Medical Center, 1105 AZ Amsterdam, The Netherlands
| | - Mieke M van Haelst
- Department of Human Genetics, Amsterdam University Medical Center, 1105 AZ Amsterdam, The Netherlands
| | - Patric J D Delhanty
- Obesity Center CGG and Expertise Center Genetic Obesity, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, The Netherlands
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, The Netherlands
| | - Jenny A Visser
- Obesity Center CGG and Expertise Center Genetic Obesity, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, The Netherlands
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, The Netherlands
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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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Rajcsanyi LS, Zheng Y, Herpertz-Dahlmann B, Seitz J, de Zwaan M, Herzog W, Ehrlich S, Zipfel S, Giel K, Egberts K, Burghardt R, Föcker M, Antel J, Fischer-Posovszky P, Hebebrand J, Hinney A. Unexpected identification of obesity-associated mutations in LEP and MC4R genes in patients with anorexia nervosa. Sci Rep 2024; 14:7067. [PMID: 38528040 PMCID: PMC10963783 DOI: 10.1038/s41598-024-57517-w] [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: 01/10/2024] [Accepted: 03/19/2024] [Indexed: 03/27/2024] Open
Abstract
Mutations leading to a reduced or loss of function in genes of the leptin-melanocortin system confer a risk for monogenic forms of obesity. Yet, gain of function variants in the melanocortin-4-receptor (MC4R) gene predispose to a lower BMI. In individuals with reduced body weight, we thus expected mutations leading to an enhanced function in the respective genes, like leptin (LEP) and MC4R. Therefore, we have Sanger sequenced the coding regions of LEP and MC4R in 462 female patients with anorexia nervosa (AN), and 445 healthy-lean controls. In total, we have observed four and eight variants in LEP and MC4R, respectively. Previous studies showed different functional in vitro effects for the detected frameshift and non-synonymous variants: (1) LEP: reduced/loss of function (p.Val94Met), (2) MC4R: gain of function (p.Val103Ile, p.Ile251Leu), reduced or loss of function (p.Thr112Met, p.Ser127Leu, p.Leu211fsX) and without functional in vitro data (p.Val50Leut). In LEP, the variant p.Val94Met was detected in one patient with AN. For MC4R variants, one patient with AN carried the frameshift variant p.Leu211fsX. One patient with AN was heterozygous for two variants at the MC4R (p.Val103Ile and p.Ser127Leu). All other functionally relevant variants were detected in similar frequencies in patients with AN and lean individuals.
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Affiliation(s)
- Luisa Sophie Rajcsanyi
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Virchowstraße 174, 45147, Essen, Germany.
- Center for Translational Neuro- and Behavioural Sciences, University Hospital Essen, Essen, Germany.
- Section for Molecular Genetics of Mental Disorders, University Hospital Essen, Essen, Germany.
- Institute of Sex- and Gender-Sensitive Medicine, University Hospital Essen, Essen, Germany.
| | - Yiran Zheng
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Virchowstraße 174, 45147, Essen, Germany
- Center for Translational Neuro- and Behavioural Sciences, University Hospital Essen, Essen, Germany
| | - Beate Herpertz-Dahlmann
- Department of Child and Adolescent Psychiatry and Psychotherapy, University Hospital of the RWTH Aachen, Aachen, Germany
| | - Jochen Seitz
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Virchowstraße 174, 45147, Essen, Germany
- Department of Child and Adolescent Psychiatry and Psychotherapy, University Hospital of the RWTH Aachen, Aachen, Germany
| | - Martina de Zwaan
- Department of Psychosomatic Medicine and Psychotherapy, Hannover Medical School, Hannover, Germany
| | - Wolfgang Herzog
- Department of Internal Medicine II, General Internal and Psychosomatic Medicine, University of Heidelberg, Heidelberg, Germany
| | - Stefan Ehrlich
- Eating Disorders Research and Treatment Center, Department of Child and Adolescent Psychiatry, Faculty of Medicine, TU Dresden, Dresden, Germany
- Translational Developmental Neuroscience Section, Division of Psychological and Social Medicine and Developmental Neurosciences, Faculty of Medicine, TU Dresden, Dresden, Germany
| | - Stephan Zipfel
- Department of Psychosomatic Medicine and Psychotherapy, Medical University Hospital Tübingen, Tübingen, Germany
- Center of Excellence in Eating Disorders KOMET, Tübingen, Germany
| | - Katrin Giel
- Department of Psychosomatic Medicine and Psychotherapy, Medical University Hospital Tübingen, Tübingen, Germany
- Center of Excellence in Eating Disorders KOMET, Tübingen, Germany
| | - Karin Egberts
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Würzburg, Würzburg, Germany
| | - Roland Burghardt
- Oberberg Clinic for Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, Fasanenkiez, Berlin, Germany
| | - Manuel Föcker
- Department of Child and Adolescent Psychiatry, University Hospital Münster, Munster, Germany
- LWL-University Hospital Hamm for Child and Adolescent Psychiatry, Ruhr-University Bochum, Hamm, Germany
| | - Jochen Antel
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Virchowstraße 174, 45147, Essen, Germany
- Center for Translational Neuro- and Behavioural Sciences, University Hospital Essen, Essen, Germany
| | | | - Johannes Hebebrand
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Virchowstraße 174, 45147, Essen, Germany
- Center for Translational Neuro- and Behavioural Sciences, University Hospital Essen, Essen, Germany
| | - Anke Hinney
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Virchowstraße 174, 45147, Essen, Germany
- Center for Translational Neuro- and Behavioural Sciences, University Hospital Essen, Essen, Germany
- Section for Molecular Genetics of Mental Disorders, University Hospital Essen, Essen, Germany
- Institute of Sex- and Gender-Sensitive Medicine, University Hospital Essen, Essen, Germany
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Nürnberg B, Beer-Hammer S, Reisinger E, Leiss V. Non-canonical G protein signaling. Pharmacol Ther 2024; 255:108589. [PMID: 38295906 DOI: 10.1016/j.pharmthera.2024.108589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 12/18/2023] [Accepted: 01/08/2024] [Indexed: 02/17/2024]
Abstract
The original paradigm of classical - also referred to as canonical - cellular signal transduction of heterotrimeric G proteins (G protein) is defined by a hierarchical, orthograde interaction of three players: the agonist-activated G protein-coupled receptor (GPCR), which activates the transducing G protein, that in turn regulates its intracellular effectors. This receptor-transducer-effector concept was extended by the identification of regulators and adapters such as the regulators of G protein signaling (RGS), receptor kinases like βARK, or GPCR-interacting arrestin adapters that are integrated into this canonical signaling process at different levels to enable fine-tuning. Finally, the identification of atypical signaling mechanisms of classical regulators, together with the discovery of novel modulators, added a new and fascinating dimension to the cellular G protein signal transduction. This heterogeneous group of accessory G protein modulators was coined "activators of G protein signaling" (AGS) proteins and plays distinct roles in canonical and non-canonical G protein signaling pathways. AGS proteins contribute to the control of essential cellular functions such as cell development and division, intracellular transport processes, secretion, autophagy or cell movements. As such, they are involved in numerous biological processes that are crucial for diseases, like diabetes mellitus, cancer, and stroke, which represent major health burdens. Although the identification of a large number of non-canonical G protein signaling pathways has broadened the spectrum of this cellular communication system, their underlying mechanisms, functions, and biological effects are poorly understood. In this review, we highlight and discuss atypical G protein-dependent signaling mechanisms with a focus on inhibitory G proteins (Gi) involved in canonical and non-canonical signal transduction, review recent developments and open questions, address the potential of new approaches for targeted pharmacological interventions.
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Affiliation(s)
- Bernd Nürnberg
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomics, and ICePhA Mouse Clinic, University of Tübingen, Wilhelmstraße 56, D-72074 Tübingen, Germany.
| | - Sandra Beer-Hammer
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomics, and ICePhA Mouse Clinic, University of Tübingen, Wilhelmstraße 56, D-72074 Tübingen, Germany
| | - Ellen Reisinger
- Gene Therapy for Hearing Impairment Group, Department of Otolaryngology - Head & Neck Surgery, University of Tübingen Medical Center, Elfriede-Aulhorn-Straße 5, D-72076 Tübingen, Germany
| | - Veronika Leiss
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomics, and ICePhA Mouse Clinic, University of Tübingen, Wilhelmstraße 56, D-72074 Tübingen, Germany
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5
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Makkonen K, Jännäri M, Crisóstomo L, Kuusi M, Patyra K, Melnyk V, Linnossuo V, Ojala J, Ravi R, Löf C, Mäkelä JA, Miettinen P, Laakso S, Ojaniemi M, Jääskeläinen J, Laakso M, Bossowski F, Sawicka B, Stożek K, Bossowski A, Kleinau G, Scheerer P, FinnGen F, Reeve MP, Kero J. Mechanisms of thyrotropin receptor-mediated phenotype variability deciphered by gene mutations and M453T-knockin model. JCI Insight 2024; 9:e167092. [PMID: 38194289 PMCID: PMC11143923 DOI: 10.1172/jci.insight.167092] [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: 11/10/2022] [Accepted: 01/05/2024] [Indexed: 01/10/2024] Open
Abstract
The clinical spectrum of thyrotropin receptor-mediated (TSHR-mediated) diseases varies from loss-of-function mutations causing congenital hypothyroidism to constitutively active mutations (CAMs) leading to nonautoimmune hyperthyroidism (NAH). Variation at the TSHR locus has also been associated with altered lipid and bone metabolism and autoimmune thyroid diseases. However, the extrathyroidal roles of TSHR and the mechanisms underlying phenotypic variability among TSHR-mediated diseases remain unclear. Here we identified and characterized TSHR variants and factors involved in phenotypic variability in different patient cohorts, the FinnGen database, and a mouse model. TSHR CAMs were found in all 16 patients with NAH, with 1 CAM in an unexpected location in the extracellular leucine-rich repeat domain (p.S237N) and another in the transmembrane domain (p.I640V) in 2 families with distinct hyperthyroid phenotypes. In addition, screening of the FinnGen database revealed rare functional variants as well as distinct common noncoding TSHR SNPs significantly associated with thyroid phenotypes, but there was no other significant association between TSHR variants and more than 2,000 nonthyroid disease endpoints. Finally, our TSHR M453T-knockin model revealed that the phenotype was dependent on the mutation's signaling properties and was ameliorated by increased iodine intake. In summary, our data show that TSHR-mediated disease risk can be modified by variants at the TSHR locus both inside and outside the coding region as well as by altered TSHR-signaling and dietary iodine, supporting the need for personalized treatment strategies.
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Affiliation(s)
- Kristiina Makkonen
- Department of Clinical Sciences, Faculty of Medicine, and
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Meeri Jännäri
- Department of Clinical Sciences, Faculty of Medicine, and
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Luís Crisóstomo
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Matilda Kuusi
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Konrad Patyra
- Department of Clinical Sciences, Faculty of Medicine, and
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | | | - Veli Linnossuo
- Department of Clinical Sciences, Faculty of Medicine, and
| | - Johanna Ojala
- Department of Clinical Sciences, Faculty of Medicine, and
| | - Rowmika Ravi
- Department of Clinical Sciences, Faculty of Medicine, and
| | - Christoffer Löf
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Juho-Antti Mäkelä
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Päivi Miettinen
- New Children’s Hospital, Helsinki University Hospital, Helsinki, Finland
| | - Saila Laakso
- New Children’s Hospital, Helsinki University Hospital, Helsinki, Finland
| | - Marja Ojaniemi
- Department of Pediatrics and Adolescence, PEDEGO Research Unit and Medical Research Center, University and University Hospital of Oulu, Oulu, Finland
| | | | - Markku Laakso
- Institute of Clinical Medicine, Internal Medicine, University of Eastern Finland, Kuopio, Finland
| | - Filip Bossowski
- Department of Pediatrics, Endocrinology, Diabetes with a Cardiology Unit, Medical University in Białystok, Bialystok, Poland
| | - Beata Sawicka
- Department of Pediatrics, Endocrinology, Diabetes with a Cardiology Unit, Medical University in Białystok, Bialystok, Poland
| | - Karolina Stożek
- Department of Pediatrics, Endocrinology, Diabetes with a Cardiology Unit, Medical University in Białystok, Bialystok, Poland
| | - Artur Bossowski
- Department of Pediatrics, Endocrinology, Diabetes with a Cardiology Unit, Medical University in Białystok, Bialystok, Poland
| | - Gunnar Kleinau
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, and
- Humboldt - Universität zu Berlin, Institute of Medical Physics, Biophysics, Group Structural Biology of Cellular Signaling, Berlin, Germany
| | - Patrick Scheerer
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, and
- Humboldt - Universität zu Berlin, Institute of Medical Physics, Biophysics, Group Structural Biology of Cellular Signaling, Berlin, Germany
| | - FinnGen FinnGen
- Institute for Molecular Medicine Finland, HiLIFE, University of Helsinki, Helsinki, Finland
- FinnGen is detailed in Supplemental Acknowledgments
| | - Mary Pat Reeve
- Institute for Molecular Medicine Finland, HiLIFE, University of Helsinki, Helsinki, Finland
| | - Jukka Kero
- Department of Clinical Sciences, Faculty of Medicine, and
- Department of Pediatrics and Adolescent Medicine, Turku University Hospital, Turku, Finland
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Metzger PJ, Zhang A, Carlson BA, Sun H, Cui Z, Li Y, Jahnke MT, Layton DR, Gupta MB, Liu N, Kostenis E, Gavrilova O, Chen M, Weinstein LS. A human obesity-associated MC4R mutation with defective Gq/11α signaling leads to hyperphagia in mice. J Clin Invest 2024; 134:e165418. [PMID: 38175730 PMCID: PMC10869179 DOI: 10.1172/jci165418] [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: 09/14/2022] [Accepted: 12/21/2023] [Indexed: 01/06/2024] Open
Abstract
Melanocortin 4 receptor (MC4R) mutations are the most common cause of human monogenic obesity and are associated with hyperphagia and increased linear growth. While MC4R is known to activate Gsα/cAMP signaling, a substantial proportion of obesity-associated MC4R mutations do not affect MC4R/Gsα signaling. To further explore the role of specific MC4R signaling pathways in the regulation of energy balance, we examined the signaling properties of one such mutant, MC4R (F51L), as well as the metabolic consequences of MC4RF51L mutation in mice. The MC4RF51L mutation produced a specific defect in MC4R/Gq/11α signaling and led to obesity, hyperphagia, and increased linear growth in mice. The ability of a melanocortin agonist to acutely inhibit food intake when delivered to the paraventricular nucleus (PVN) was lost in MC4RF51L mice, as well as in WT mice in which a specific Gq/11α inhibitor was delivered to the PVN; this provided evidence that a Gsα-independent signaling pathway, namely Gq/11α, significantly contributes to the actions of MC4R on food intake and linear growth. These results suggest that a biased MC4R agonist that primarily activates Gq/11α may be a potential agent to treat obesity with limited untoward cardiovascular and other side effects.
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Affiliation(s)
| | | | | | - Hui Sun
- Metabolic Diseases Branch and
| | - Zhenzhong Cui
- Mouse Metabolism Core Laboratory, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NIH, Bethesda, Maryland, USA
| | | | | | | | | | - Naili Liu
- Mouse Metabolism Core Laboratory, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NIH, Bethesda, Maryland, USA
| | - Evi Kostenis
- Molecular, Cellular, and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Oksana Gavrilova
- Mouse Metabolism Core Laboratory, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NIH, Bethesda, Maryland, USA
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7
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Mohammed I, Selvaraj S, Ahmed WS, Al-Barazenji T, Hammad AS, Dauleh H, Saraiva LR, Al-Shafai M, Hussain K. Functional Characterization of Novel MC4R Variants Identified in Two Unrelated Patients with Morbid Obesity in Qatar. Int J Mol Sci 2023; 24:16361. [PMID: 38003551 PMCID: PMC10671262 DOI: 10.3390/ijms242216361] [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: 09/17/2023] [Revised: 11/06/2023] [Accepted: 11/07/2023] [Indexed: 11/26/2023] Open
Abstract
The leptin-melanocortin pathway is pivotal in appetite and energy homeostasis. Pathogenic variants in genes involved in this pathway lead to severe early-onset monogenic obesity (MO). The MC4R gene plays a central role in leptin-melanocortin signaling, and heterozygous variants in this gene are the most common cause of MO. A targeted gene panel consisting of 52 obesity-related genes was used to screen for variants associated with obesity. Variants were analyzed and filtered to identify potential disease-causing activity and validated using Sanger sequencing. We identified two novel heterozygous variants, c.253A>G p.Ser85Gly and c.802T>C p.Tyr268His, in the MC4R gene in two unrelated patients with morbid obesity and evaluated the functional impact of these variants. The impact of the variants on the MC4R gene was assessed using in silico prediction tools and molecular dynamics simulation. To further study the pathogenicity of the identified variants, GT1-7 cells were transfected with plasmid DNA encoding either wild-type or mutant MC4R variants. The effects of allelic variations in the MC4R gene on cAMP synthesis, MC4R protein level, and activation of PKA, ERB, and CREB signaling pathways in both stimulated and unstimulated ɑ-MSH paradigms were determined for their functional implications. In silico analysis suggested that the variants destabilized the MC4R structure and affected the overall dynamics of the MC4R protein, possibly leading to intracellular receptor retention. In vitro analysis of the functional impact of these variants showed a significant reduction in cell surface receptor expression and impaired extracellular ligand binding activity, leading to reduced cAMP production. Our analysis shows that the variants do not affect total protein expression; however, they are predicted to affect the post-translational localization of the MC4R protein to the cell surface and impair downstream signaling cascades such as PKA, ERK, and CREB signaling pathways. This finding might help our patients to benefit from the novel therapeutic advances for monogenic forms of obesity.
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Affiliation(s)
- Idris Mohammed
- College of Health & Life Sciences, Hamad Bin Khalifa University, Doha P.O. Box 34110, Qatar; (I.M.); (W.S.A.); (L.R.S.)
- Division of Endocrinology, Department of Pediatric Medicine, Sidra Medicine, Doha P.O. Box 26999, Qatar;
| | - Senthil Selvaraj
- Department of Disease Modeling and Therapeutics, Sidra Medicine, Doha P.O. Box 26999, Qatar;
| | - Wesam S. Ahmed
- College of Health & Life Sciences, Hamad Bin Khalifa University, Doha P.O. Box 34110, Qatar; (I.M.); (W.S.A.); (L.R.S.)
| | - Tara Al-Barazenji
- Department of Biomedical Sciences, College of Health Sciences, QU Health, Qatar University, Doha P.O. Box 2713, Qatar; (T.A.-B.); (A.S.H.)
| | - Ayat S Hammad
- Department of Biomedical Sciences, College of Health Sciences, QU Health, Qatar University, Doha P.O. Box 2713, Qatar; (T.A.-B.); (A.S.H.)
- Biomedical Research Center, Qatar University, Doha P.O. Box 2713, Qatar
| | - Hajar Dauleh
- Division of Endocrinology, Department of Pediatric Medicine, Sidra Medicine, Doha P.O. Box 26999, Qatar;
| | - Luis R. Saraiva
- College of Health & Life Sciences, Hamad Bin Khalifa University, Doha P.O. Box 34110, Qatar; (I.M.); (W.S.A.); (L.R.S.)
- Department of Disease Modeling and Therapeutics, Sidra Medicine, Doha P.O. Box 26999, Qatar;
| | - Mashael Al-Shafai
- Department of Biomedical Sciences, College of Health Sciences, QU Health, Qatar University, Doha P.O. Box 2713, Qatar; (T.A.-B.); (A.S.H.)
- Biomedical Research Center, Qatar University, Doha P.O. Box 2713, Qatar
| | - Khalid Hussain
- Division of Endocrinology, Department of Pediatric Medicine, Sidra Medicine, Doha P.O. Box 26999, Qatar;
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8
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Jerjen CP, Kumaran SJ, Liesegang A, Hall E, Wichert B, Haase B. Melanocortin-4 receptor and proopiomelanocortin: Candidate genes for obesity in domestic shorthair cats. Anim Genet 2023; 54:637-642. [PMID: 37365843 DOI: 10.1111/age.13335] [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: 01/26/2023] [Revised: 05/16/2023] [Accepted: 06/05/2023] [Indexed: 06/28/2023]
Abstract
Obesity is an escalating global health problem affecting both humans and companion animals. In cats it is associated with increased mortality and multiple diseases, including diabetes mellitus. Two genes coding for proteins known to play a critical role in energy homeostasis across species are the proopiomelanocortin (POMC) gene and the melanocortin-4 receptor (MC4R) gene. A missense variant in the coding sequence of the feline MC4R (MC4R:c.92C>T) has been reported to be associated with diabetes and overweight in domestic shorthair cats, and while variants in the POMC gene are known to cause obesity in humans and dogs, variants in POMC and their association with feline obesity and diabetes mellitus have not been investigated to date. The current study aimed to assess the association between the previously described MC4R variant and body condition score (BCS), as well as body fat content (%BF) in 89 non-diabetic domestic shorthair cats. Furthermore, we investigated the feline POMC gene as a potential candidate gene for obesity. Our results indicate that the MC4R:c.92C>T polymorphism is not associated with BCS or %BF in non-diabetic domestic shorthair cats. The mutation analysis of all POMC exons identified two missense variants, with a variant in exon 1 (c.28G>C; p.G10R) predicted to be damaging. The variant was subsequently assessed in all 89 cats, and cats heterozygous for the variant had a significantly increased body condition score (p = 0.03) compared with cats homozygous for the wild-type allele. Results from our study provide additional evidence that the previously described variant in MC4R is not associated with obesity in domestic shorthair cats. More importantly, we have identified a novel variant in the POMC gene, which might play a role in increased body condition score and body fat content in domestic shorthair cats.
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Affiliation(s)
- C P Jerjen
- Faculty of Science, Sydney School of Veterinary Science, University of Sydney, Camperdown, New South Wales, Australia
| | - S J Kumaran
- Faculty of Science, Sydney School of Veterinary Science, University of Sydney, Camperdown, New South Wales, Australia
| | - A Liesegang
- Vetsuisse Faculty, Institute of Animal Nutrition and Dietetics, University of Zurich, Zurich, Switzerland
| | - E Hall
- Faculty of Science, Sydney School of Veterinary Science, University of Sydney, Camperdown, New South Wales, Australia
| | - B Wichert
- Vetsuisse Faculty, Institute of Animal Nutrition and Dietetics, University of Zurich, Zurich, Switzerland
| | - B Haase
- Faculty of Science, Sydney School of Veterinary Science, University of Sydney, Camperdown, New South Wales, Australia
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9
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Wei R, Li D, Jia S, Chen Y, Wang J. MC4R in Central and Peripheral Systems. Adv Biol (Weinh) 2023; 7:e2300035. [PMID: 37043700 DOI: 10.1002/adbi.202300035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Revised: 02/25/2023] [Indexed: 04/14/2023]
Abstract
Obesity has emerged as a critical and urgent health burden during the current global pandemic. Among multiple genetic causes, melanocortin receptor-4 (MC4R), involved in food intake and energy metabolism regulation through various signaling pathways, has been reported to be the lead genetic factor in severe and early onset obesity and hyperphagia disorders. Most previous studies have illustrated the roles of MC4R signaling in energy intake versus expenditure in the central system, while some evidence indicates that MC4R is also expressed in peripheral systems, such as the gut and endocrine organs. However, its physiopathological function remains poorly defined. This review aims to depict the central and peripheral roles of MC4R in energy metabolism and endocrine hormone homeostasis, the diversity of phenotypes, biased downstream signaling caused by distinct MC4R mutations, and current drug development targeting the receptor.
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Affiliation(s)
- Ran Wei
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin 2nd Road, Shanghai, 200025, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Shanghai, 200025, China
- Department of Endocrinology, Shanghai Fifth People's Hospital, Fudan University, Shanghai, 200240, China
| | - Danjie Li
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin 2nd Road, Shanghai, 200025, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Shanghai, 200025, China
| | - Sheng Jia
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin 2nd Road, Shanghai, 200025, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Shanghai, 200025, China
| | - Yuhong Chen
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin 2nd Road, Shanghai, 200025, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Shanghai, 200025, China
| | - Jiqiu Wang
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin 2nd Road, Shanghai, 200025, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Shanghai, 200025, China
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10
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Schröder SK, Gasterich N, Weiskirchen S, Weiskirchen R. Lipocalin 2 receptors: facts, fictions, and myths. Front Immunol 2023; 14:1229885. [PMID: 37638032 PMCID: PMC10451079 DOI: 10.3389/fimmu.2023.1229885] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Accepted: 07/18/2023] [Indexed: 08/29/2023] Open
Abstract
The human 25-kDa Lipocalin 2 (LCN2) was first identified and purified as a protein that in part is associated with gelatinase from neutrophils. This protein shows a high degree of sequence similarity with the deduced sequences of rat α2-microglobulin-related protein and the mouse protein 24p3. Based on its typical lipocalin fold, which consists of an eight-stranded, anti-parallel, symmetrical β-barrel fold structure it was initially thought that LCN2 is a circulating protein functioning as a transporter of small lipophilic molecules. However, studies in Lcn2 null mice have shown that LCN2 has bacteriostatic properties and plays a key role in innate immunity by sequestering bacterial iron siderophores. Numerous reports have further shown that LCN2 is involved in the control of cell differentiation, energy expenditure, cell death, chemotaxis, cell migration, and many other biological processes. In addition, important roles for LCN2 in health and disease have been identified in Lcn2 null mice and multiple molecular pathways required for regulation of Lcn2 expression have been identified. Nevertheless, although six putative receptors for LCN2 have been proposed, there is a fundamental lack in understanding of how these cell-surface receptors transmit and amplify LCN2 to the cell. In the present review we summarize the current knowledge on LCN2 receptors and discuss inconsistencies, misinterpretations and false assumptions in the understanding of these potential LCN2 receptors.
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Affiliation(s)
- Sarah K. Schröder
- Institute of Molecular Pathobiochemistry, Experimental Gene Therapy and Clinical Chemistry (IFMPEGKC), RWTH University Hospital Aachen, Aachen, Germany
| | - Natalie Gasterich
- Institute of Neuroanatomy, RWTH University Hospital Aachen, Aachen, Germany
| | - Sabine Weiskirchen
- Institute of Molecular Pathobiochemistry, Experimental Gene Therapy and Clinical Chemistry (IFMPEGKC), RWTH University Hospital Aachen, Aachen, Germany
| | - Ralf Weiskirchen
- Institute of Molecular Pathobiochemistry, Experimental Gene Therapy and Clinical Chemistry (IFMPEGKC), RWTH University Hospital Aachen, Aachen, Germany
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11
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Botha R, Kumar SS, Grimsey NL, Mountjoy KG. A unique melanocortin-4-receptor signaling profile for obesity-associated constitutively active variants. J Mol Endocrinol 2023; 71:e230008. [PMID: 37040537 PMCID: PMC10304906 DOI: 10.1530/jme-23-0008] [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: 03/08/2023] [Accepted: 04/11/2023] [Indexed: 04/13/2023]
Abstract
The melanocortin-4 receptor (MC4R) plays a critical role in regulating energy homeostasis. Studies on obesogenic human MC4R (hMC4R) variants have not yet revealed how hMC4R maintains body weight. Here, we identified a signaling profile for obesogenic constitutively active H76R and L250Q hMC4R variants transfected in HEK293 cells that included constitutive activity for adenylyl cyclase (AC), cyclic adenosine monophosphate (cAMP) response element (CRE)-driven transcription, and calcium mobilization but not phosphorylated extracellular signal-regulated kinase 1/2 (pERK1/2) activity. Importantly, the signaling profile included impaired α-melanocyte-stimulating hormone-induced CRE-driven transcription but not impaired α-melanocyte-stimulating hormone-induced AC, calcium, or pERK1/2. This profile was not observed for transfected H158R, a constitutively active hMC4R variant associated with overweight but not obesity. We concluded that there is potential for α-melanocyte-stimulating hormone-induced CRE-driven transcription in HEK293 cells transfected with obesogenic hMC4R variants to be the key predictive tool for determining whether they exhibit loss of function. Furthermore, in vivo, α-melanocyte-stimulating hormone-induced hMC4R CRE-driven transcription may be key for maintaining body weight.
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Affiliation(s)
- Rikus Botha
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, New Zealand
| | - Shree S Kumar
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, New Zealand
| | - Natasha L Grimsey
- Department of Pharmacology, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, New Zealand
- Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, New Zealand
- Maurice Wilkins Centre for Biodiscovery, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, New Zealand
| | - Kathleen G Mountjoy
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, New Zealand
- Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, New Zealand
- Maurice Wilkins Centre for Biodiscovery, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, New Zealand
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, New Zealand
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12
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Daini E, Vandini E, Bodria M, Liao W, Baraldi C, Secco V, Ottani A, Zoli M, Giuliani D, Vilella A. Melanocortin receptor agonist NDP-α-MSH improves cognitive deficits and microgliosis but not amyloidosis in advanced stages of AD progression in 5XFAD and 3xTg mice. Front Immunol 2023; 13:1082036. [PMID: 36703981 PMCID: PMC9871936 DOI: 10.3389/fimmu.2022.1082036] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 12/21/2022] [Indexed: 01/11/2023] Open
Abstract
Introduction Alzheimer's disease (AD) is the most frequent cause of dementia and still lacks effective therapy. Clinical signs of AD include low levels of endogenous melanocortins (MCs) and previous studies have shown that treatment with MC analogs induces neuroprotection in the early stages of AD. Methods We investigated the neuroprotective role of MCs in two transgenic mouse models of severe AD using 5 and 7 month-old (mo) 5XFAD mice and 9 and 12 mo 3xTg mice. These mice were subjected to a chronic stimulation of MC receptors (MCRs) with MC analogue Nle4-D-Phe7-α-melanocyte stimulating hormone (NDP-α-MSH, 340 μg/kg, i.p.). Mouse behavior and ex-vivo histological and biochemical analyses were performed after 50 days of treatment. Results Our analysis demonstrated an improvement in cognitive abilities of AD mice at late stage of AD progression. We also showed that these protective effects are associated with decreased levels of hyperphosphorylated Tau but not with Aβ burden, that was unaffected in the hippocampus and in the cortex of AD mice. In addition, an age-dependent NDP effect on glial reactivity was observed only in 3xTg mice whereas a global downregulation of p38 mitogen-activated protein kinase was selectively observed in 7 mo 5XFAD and 14 mo 3xTg mice. Conclusion Our results suggest that MCR stimulation by NDP-α-MSH could represent a promising therapeutic strategy in managing cognitive decline also at late stage of AD, whereas the effects on neuroinflammation may be restricted to specific stages of AD progression.
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Affiliation(s)
- Eleonora Daini
- Department of Biomedical, Metabolic and Neural Sciences, Laboratory of Molecular and Cellular Neurobiology, University of Modena and Reggio Emilia, Modena, Italy
| | - Eleonora Vandini
- Department of Biomedical, Metabolic and Neural Sciences, Pharmacology Unit, University of Modena and Reggio Emilia, Modena, Italy
| | - Martina Bodria
- Department of Biomedical, Metabolic and Neural Sciences, Laboratory of Molecular and Cellular Neurobiology, University of Modena and Reggio Emilia, Modena, Italy
| | - Wenjie Liao
- Department of Biomedical, Metabolic and Neural Sciences, Laboratory of Molecular and Cellular Neurobiology, University of Modena and Reggio Emilia, Modena, Italy
| | - Carlo Baraldi
- Department of Biomedical, Metabolic and Neural Sciences, Laboratory of Molecular and Cellular Neurobiology, University of Modena and Reggio Emilia, Modena, Italy
| | - Valentina Secco
- Department of Biomedical, Metabolic and Neural Sciences, Laboratory of Molecular and Cellular Neurobiology, University of Modena and Reggio Emilia, Modena, Italy
| | - Alessandra Ottani
- Department of Biomedical, Metabolic and Neural Sciences, Pharmacology Unit, University of Modena and Reggio Emilia, Modena, Italy
| | - Michele Zoli
- Department of Biomedical, Metabolic and Neural Sciences, Laboratory of Molecular and Cellular Neurobiology, University of Modena and Reggio Emilia, Modena, Italy
| | - Daniela Giuliani
- Department of Biomedical, Metabolic and Neural Sciences, Pharmacology Unit, University of Modena and Reggio Emilia, Modena, Italy
| | - Antonietta Vilella
- Department of Biomedical, Metabolic and Neural Sciences, Laboratory of Molecular and Cellular Neurobiology, University of Modena and Reggio Emilia, Modena, Italy,*Correspondence: Antonietta Vilella,
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13
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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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14
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Hinney A, Körner A, Fischer-Posovszky P. The promise of new anti-obesity therapies arising from knowledge of genetic obesity traits. Nat Rev Endocrinol 2022; 18:623-637. [PMID: 35902734 PMCID: PMC9330928 DOI: 10.1038/s41574-022-00716-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/17/2022] [Indexed: 02/07/2023]
Abstract
Obesity is a multifactorial and complex disease that often manifests in early childhood with a lifelong burden. Polygenic and monogenic obesity are driven by the interaction between genetic predisposition and environmental factors. Polygenic variants are frequent and confer small effect sizes. Rare monogenic obesity syndromes are caused by defined pathogenic variants in single genes with large effect sizes. Most of these genes are involved in the central nervous regulation of body weight; for example, genes of the leptin-melanocortin pathway. Clinically, patients with monogenic obesity present with impaired satiety, hyperphagia and pronounced food-seeking behaviour in early childhood, which leads to severe early-onset obesity. With the advent of novel pharmacological treatment options emerging for monogenic obesity syndromes that target the central melanocortin pathway, genetic testing is recommended for patients with rapid weight gain in infancy and additional clinical suggestive features. Likewise, patients with obesity associated with hypothalamic damage or other forms of syndromic obesity involving energy regulatory circuits could benefit from these novel pharmacological treatment options. Early identification of patients affected by syndromic obesity will lead to appropriate treatment, thereby preventing the development of obesity sequelae, avoiding failure of conservative treatment approaches and alleviating stigmatization of patients and their families.
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Affiliation(s)
- Anke Hinney
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy and University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
- Center for Translational Neuro- and Behavioral Sciences, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
| | - Antje Körner
- Leipzig University, Medical Faculty, Hospital for Children and Adolescents, Centre of Paediatric Research (CPL), Leipzig, Germany
- LIFE Child, Leipzig Research Centre for Civilization Diseases, Leipzig, Germany
- Helmholtz Institute for Metabolic, Obesity and Vascular Research (HI-MAG) of the Helmholtz Zentrum München at the University of Leipzig and University Hospital Leipzig, Leipzig, Germany
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15
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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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Piper NBC, Whitfield EA, Stewart GD, Xu X, Furness SGB. Targeting appetite and satiety in diabetes and obesity, via G protein-coupled receptors. Biochem Pharmacol 2022; 202:115115. [PMID: 35671790 DOI: 10.1016/j.bcp.2022.115115] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 05/26/2022] [Accepted: 05/27/2022] [Indexed: 11/17/2022]
Abstract
Type 2 diabetes and obesity have reached pandemic proportions throughout the world, so much so that the World Health Organisation coined the term "Globesity" to help encapsulate the magnitude of the problem. G protein-coupled receptors (GPCRs) are highly tractable drug targets due to their wide involvement in all aspects of physiology and pathophysiology, indeed, GPCRs are the targets of approximately 30% of the currently approved drugs. GPCRs are also broadly involved in key physiologies that underlie type 2 diabetes and obesity including feeding reward, appetite and satiety, regulation of blood glucose levels, energy homeostasis and adipose function. Despite this, only two GPCRs are the target of approved pharmaceuticals for treatment of type 2 diabetes and obesity. In this review we discuss the role of these, and select other candidate GPCRs, involved in various facets of type 2 diabetic or obese pathophysiology, how they might be targeted and the potential reasons why pharmaceuticals against these targets have not progressed to clinical use. Finally, we provide a perspective on the current development pipeline of anti-obesity drugs that target GPCRs.
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Affiliation(s)
- Noah B C Piper
- Receptor Transducer Coupling Laboratory, School of Biomedical Sciences, Faculty of Medicine, University of Queensland, St. Lucia, QLD 4072, Australia
| | - Emily A Whitfield
- Receptor Transducer Coupling Laboratory, School of Biomedical Sciences, Faculty of Medicine, University of Queensland, St. Lucia, QLD 4072, Australia
| | - Gregory D Stewart
- Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences & Department of Pharmacology Monash University, Parkville, VIC 3052, Australia
| | - Xiaomeng Xu
- Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences & Department of Pharmacology Monash University, Parkville, VIC 3052, Australia
| | - Sebastian G B Furness
- Receptor Transducer Coupling Laboratory, School of Biomedical Sciences, Faculty of Medicine, University of Queensland, St. Lucia, QLD 4072, Australia; Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences & Department of Pharmacology Monash University, Parkville, VIC 3052, Australia.
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17
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Structures of active melanocortin-4 receptor-Gs-protein complexes with NDP-α-MSH and setmelanotide. Cell Res 2021; 31:1176-1189. [PMID: 34561620 PMCID: PMC8563958 DOI: 10.1038/s41422-021-00569-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Accepted: 08/31/2021] [Indexed: 02/07/2023] Open
Abstract
The melanocortin-4 receptor (MC4R), a hypothalamic master regulator of energy homeostasis and appetite, is a class A G-protein-coupled receptor and a prime target for the pharmacological treatment of obesity. Here, we present cryo-electron microscopy structures of MC4R–Gs-protein complexes with two drugs recently approved by the FDA, the peptide agonists NDP-α-MSH and setmelanotide, with 2.9 Å and 2.6 Å resolution. Together with signaling data from structure-derived MC4R mutants, the complex structures reveal the agonist-induced origin of transmembrane helix (TM) 6-regulated receptor activation. The ligand-binding modes of NDP-α-MSH, a high-affinity linear variant of the endogenous agonist α-MSH, and setmelanotide, a cyclic anti-obesity drug with biased signaling toward Gq/11, underline the key role of TM3 in ligand-specific interactions and of calcium ion as a ligand-adaptable cofactor. The agonist-specific TM3 interplay subsequently impacts receptor–Gs-protein interfaces at intracellular loop 2, which also regulates the G-protein coupling profile of this promiscuous receptor. Finally, our structures reveal mechanistic details of MC4R activation/inhibition, and provide important insights into the regulation of the receptor signaling profile which will facilitate the development of tailored anti-obesity drugs.
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Abstract
In a new paper, Wade et al. (2021) analyzed the frequency of MC4R loss-of-function (LoF) mutations in a population-based Avon Longitudinal Study of Parents and Children. The frequency was 1 in 337 and the authors showed that MC4R LoF variants significantly correlated with increased body weight and fat mass in children and adults (cumulating in additional 17.76 kg weight in adulthood). Hence, the authors provide evidence that MC4R LoF variants are more common than previously expected.
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Affiliation(s)
- Peter Kühnen
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin und Humboldt-Universität zu Berlin, Institute for Experimental Pediatric Endocrinology, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Heike Biebermann
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin und Humboldt-Universität zu Berlin, Institute for Experimental Pediatric Endocrinology, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Heiko Krude
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin und Humboldt-Universität zu Berlin, Institute for Experimental Pediatric Endocrinology, Augustenburger Platz 1, 13353 Berlin, Germany.
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Kumar SS, Ward ML, Mountjoy KG. Quantitative high-throughput assay to measure MC4R-induced intracellular calcium. J Mol Endocrinol 2021; 66:285-297. [PMID: 33739935 PMCID: PMC8111326 DOI: 10.1530/jme-20-0285] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 03/19/2021] [Indexed: 12/17/2022]
Abstract
The melanocortin-4 receptor (MC4R), a critical G-protein-coupled receptor (GPCR) regulating energy homeostasis, activates multiple signalling pathways, including mobilisation of intracellular calcium ([Ca2+]i). However, very little is known about the physiological significance of MC4R-induced [Ca2+]i since few studies measure MC4R-induced [Ca2+]i. High-throughput, read-out assays for [Ca2+]i have proven unreliable for overexpressed GPCRs like MC4R, which exhibit low sensitivity mobilising [Ca2+]i. Therefore, we developed, optimised, and validated a robust quantitative high-throughput assay using Fura-2 ratio-metric calcium dye and HEK293 cells stably transfected with MC4R. The quantitation enables direct comparisons between assays and even between different research laboratories. Assay conditions were optimised step-by-step to eliminate interference from stretch-activated receptor increases in [Ca2+]i and to maximise ligand-activated MC4R-induced [Ca2+]i. Calcium imaging was performed using a PheraStar FS multi-well plate reader. Probenecid, included in the buffers to prevent extrusion of Fura-2 dye from cells, was found to interfere with the EGTA-chelation of calcium, required to determine Rmin for quantitation of [Ca2+]i. Therefore, we developed a method to determine Rmin in specific wells without probenecid, which was run in parallel with each assay. The validation of the assay was shown by reproducible α-melanocyte-stimulating hormone (α-MSH) concentration-dependent activation of the stably expressed human MC4R (hMC4R) and mouse MC4R (mMC4R), inducing increases in [Ca2+]i, for three independent experiments. This robust, reproducible, high-throughput assay that quantitatively measures MC4R-induced mobilisation of [Ca2+]i in vitro has potential to advance the development of therapeutic drugs and understanding of MC4R signalling associated with human obesity.
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Affiliation(s)
- Shree Senthil Kumar
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Marie-Louise Ward
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Kathleen Grace Mountjoy
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, New Zealand
- Correspondence should be addressed to K G Mountjoy:
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Yang LK, Hou ZS, Tao YX. Biased signaling in naturally occurring mutations of G protein-coupled receptors associated with diverse human diseases. Biochim Biophys Acta Mol Basis Dis 2021; 1867:165973. [PMID: 32949766 PMCID: PMC7722056 DOI: 10.1016/j.bbadis.2020.165973] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 09/07/2020] [Accepted: 09/14/2020] [Indexed: 12/15/2022]
Abstract
G protein-coupled receptors (GPCRs) play critical roles in transmitting a variety of extracellular signals into the cells and regulate diverse physiological functions. Naturally occurring mutations that result in dysfunctions of GPCRs have been known as the causes of numerous diseases. Significant progresses have been made in elucidating the pathophysiology of diseases caused by mutations. The multiple intracellular signaling pathways, such as G protein-dependent and β-arrestin-dependent signaling, in conjunction with recent advances on biased agonism, have broadened the view on the molecular mechanism of disease pathogenesis. This review aims to briefly discuss biased agonism of GPCRs (biased ligands and biased receptors), summarize the naturally occurring GPCR mutations that cause biased signaling, and propose the potential pathophysiological relevance of biased mutant GPCRs associated with various endocrine diseases.
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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
| | - Zhi-Shuai Hou
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States.
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Liu Z, Sun F, Liu Z, Wang X, Jin M, Mao J, Wu Q, Yan S, Xu K, Wang K, Hu S. Effect of Sleeve Gastrectomy on Glycometabolism via Forkhead Box O1 (FoxO1)/Lipocalin-2 (LCN2) Pathway. Med Sci Monit 2020; 26:e927458. [PMID: 32845875 PMCID: PMC7780888 DOI: 10.12659/msm.927458] [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] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND The mechanism by which sleeve gastrectomy (SG) improves glycometabolism has remained unclear so far. Increasing evidence has demonstrated that bone is a regulator of glucose metabolism, and osteoblast-derived forkhead box O1 (FoxO1) and lipocalin-2 (LCN2) are regulators of energy metabolism. The aim of this study was to investigate whether the FOXO1/LCN2 signaling pathway is involved in the anti-diabetic effect of SG. MATERIAL AND METHODS Insulin resistance was induced in Wistar rats, which were then intraperitoneally injected with streptozotocin to induce a type 2 diabetic state. Levels of fasting blood glucose, serum insulin, HbA1c, and LCN2 were analyzed at corresponding time points after SG and sham surgeries. The expressions of FOXO1, LCN2, and the melanocortin 4 receptor (MC4R) in bone and hypothalamus were detected by immunofluorescence. FOXO1 siRNA was applied to downregulate FOXO1 expression in osteoblasts of rats. The influence of FOXO1 gene on expression of LCN2 was investigated in cultured osteoblasts by western blot and PCR. RESULTS Glucose metabolism in the SG group was significantly improved. The LCN2 expression in bone in the SG group was higher than that in the sham group, whereas FOXO1 expression in the SG group was lower than that in the sham group. The binding rate of LCN2 and MC4R in the hypothalamus was also higher in the SG group compared with that in the sham group. The downregulation of FOXO1 expression in osteoblasts was accompanied by upregulation of LCN2 expression. CONCLUSIONS These results suggest that the FOXO1/LCN2 signaling pathway participates in the anti-diabetic effect of SG.
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Affiliation(s)
- Zhi Liu
- Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China (mainland)
| | - Fuyun Sun
- Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China (mainland)
| | - Zitian Liu
- Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China (mainland)
| | - Xiaoyang Wang
- Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China (mainland)
| | - Mingxin Jin
- Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China (mainland)
| | - Jiajia Mao
- Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China (mainland)
| | - Qunzheng Wu
- Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China (mainland)
| | - Shaohua Yan
- Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China (mainland)
| | - Kai Xu
- Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China (mainland)
| | - Kexin Wang
- Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China (mainland)
| | - Sanyuan Hu
- Department of General Surgery, Shandong Qianfoshan Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China (mainland)
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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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Kühnen P, Wiegand S, Biebermann H. Pharmacological treatment strategies for patients with monogenic obesity. J Pediatr Endocrinol Metab 2020; 33:/j/jpem.ahead-of-print/jpem-2020-0129/jpem-2020-0129.xml. [PMID: 32619193 DOI: 10.1515/jpem-2020-0129] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 04/04/2020] [Indexed: 12/29/2022]
Abstract
The leptin melanocortin signaling pathway is playing a pivotal role for body weight regulation. Genetic defects within this cascade are leading to severe hyperphagia and early onset obesity. In most cases, due to persistent hyperphagia the affected patients are not able to stabilize body weight for a longer period of time with conservative treatment strategies based on lifestyle interventions. Therefore, it is of importance to implement alternative treatment options for these patients. This review provides an overview about the published pharmacological treatment attempts in respect to monogenic forms of obesity and summarizes recent research progress about the role of MC4R signaling and POMC derivatives for body weight regulation.
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Affiliation(s)
- Peter Kühnen
- Institute for Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Berlin Institute of Health, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Susanna Wiegand
- Berlin Institute of Health, Augustenburger Platz 1, 13353 Berlin, Germany
- Center for Social-Pediatric Care, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Heike Biebermann
- Institute for Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Berlin Institute of Health, Augustenburger Platz 1, 13353 Berlin, Germany
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Metabolic Reprogramming in Health and Disease. Int J Mol Sci 2020; 21:ijms21082768. [PMID: 32316318 PMCID: PMC7215439 DOI: 10.3390/ijms21082768] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 04/15/2020] [Indexed: 11/17/2022] Open
Abstract
This editorial aims to summarize the six scientific papers that contributed to this Special Issue.
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