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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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Zheng Y, Rajcsanyi LS, Peters T, Dempfle A, Wudy SA, Hebebrand J, Hinney A. Evaluation of the MC3R gene pertaining to body weight and height regulation and puberty development. Sci Rep 2023; 13:10419. [PMID: 37369769 DOI: 10.1038/s41598-023-37344-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 06/20/2023] [Indexed: 06/29/2023] Open
Abstract
Recent studies reported an impact of the melanocortin 3 receptor (MC3R) on the regulation of body weight, linear growth and puberty timing. Previously, allele p.44Ile of a frequent non-synonymous variant (NSV) p.Val44Ile was reported to be associated with decreased lean body mass (LBM) and later puberty in both sexes. We Sanger sequenced the coding region of MC3R in 185 children or adolescents with short normal stature (SNS) or 258 individuals with severe obesity, and 192 healthy-lean individuals. Eleven variants (six NSVs) were identified. In-silico analyses ensued. Three rare loss-of-function (LoF) variants (p.Phe45Ser, p.Arg220Ser and p.Ile298Ser) were only found in severely obese individuals. One novel highly conserved NSV (p.Ala214Val), predicted to increase protein stability, was detected in a single lean female. In the individuals with SNS, we observed deviation from Hardy-Weinberg Equilibrium (HWE) (p = 0.012) for p.Val44Ile (MAF = 11.62%). Homozygous p.44Ile carriers with SNS had an increased BMI, but this effect did not remain significant after Bonferroni correction. In line with previous findings, the detected LoF NSVs may suggest that dysfunction in MC3R is associated with decreased body height, obesity and delayed puberty.
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Affiliation(s)
- Yiran Zheng
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Virchowstr. 174, 45147, Essen, Germany.
- Center for Translational Neuro- and Behavioral Sciences, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
| | - Luisa Sophie Rajcsanyi
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Virchowstr. 174, 45147, Essen, Germany
- Center for Translational Neuro- and Behavioral Sciences, 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, Virchowstr. 174, 45147, Essen, Germany
- Center for Translational Neuro- and Behavioral Sciences, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Astrid Dempfle
- Institute of Medical Informatics and Statistics, Kiel University, Kiel, Germany
| | - Stefan A Wudy
- Division of Pediatric Endocrinology and Diabetology, Center of Child and Adolescent Medicine, Justus Liebig University, Giessen, Germany
| | - Johannes Hebebrand
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Virchowstr. 174, 45147, Essen, Germany
- Center for Translational Neuro- and Behavioral Sciences, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Anke Hinney
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Virchowstr. 174, 45147, Essen, Germany
- Center for Translational Neuro- and Behavioral Sciences, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
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Pisoni S, Marrachelli VG, Morales JM, Maestrini S, Di Blasio AM, Monleón D. Sex Dimorphism in the Metabolome of Metabolic Syndrome in Morbidly Obese Individuals. Metabolites 2022; 12:metabo12050419. [PMID: 35629923 PMCID: PMC9147578 DOI: 10.3390/metabo12050419] [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: 04/15/2022] [Revised: 04/30/2022] [Accepted: 05/03/2022] [Indexed: 12/10/2022] Open
Abstract
Adult morbid obesity is defined as abnormal or excessive fat accumulation, mostly resulting from a long-term unhealthy lifestyle. Between 10% and 30% of people with obesity exhibit low cardiometabolic risk. The metabolic syndrome has been suggested as an indicator of obesity-related metabolic dysregulation. Although the prevalence of obesity does not seem to be sex-related and metabolic syndrome occurs at all ages, in the last few years, sex-specific differences in the pathophysiology, diagnosis, and treatment of metabolic syndrome have received attention. The aim of this study was to determine the prevalence of metabolic syndrome and its components in different sex and age groups in people with metabolic unhealthy obesity and to compare them with people with metabolic healthy obesity. We analyzed the metabolome in 1350 well-phenotyped morbidly obese individuals and showed that there is a strong sex-dependent association of metabolic syndrome with circulating metabolites. Importantly, we demonstrated that metabolic dysregulation in women and men with severe obesity and metabolic syndrome is age-dependent. The metabolic profiles from our study showed age-dependent sex differences in the impact of MetS which are consistent with the cardiometabolic characterization. Although there is common ground for MetS in the metabolome of severe obesity, men older than 54 are affected in a more extensive and intensive manner. These findings strongly argue for more studies aimed at unraveling the mechanisms that underlie this sex-specific metabolic dysregulation in severe obesity. Moreover, these findings suggest that women and men might benefit from differential sex and age specific interventions to prevent the adverse cardiometabolic effects of severe obesity.
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Affiliation(s)
- Serena Pisoni
- Department of Pathology, Medicine and Odontology Faculty, University of Valencia, 46010 Valencia, Spain; (S.P.); (J.M.M.)
| | - Vannina G. Marrachelli
- Department of Physiology, Medicine and Odontology Faculty, University of Valencia, 46010 Valencia, Spain;
- Clinical Hospital Research Foundation-INCLIVA and CIBERFES, 46010 Valencia, Spain
| | - Jose M. Morales
- Department of Pathology, Medicine and Odontology Faculty, University of Valencia, 46010 Valencia, Spain; (S.P.); (J.M.M.)
- Clinical Hospital Research Foundation-INCLIVA and CIBERFES, 46010 Valencia, Spain
| | - Sabrina Maestrini
- Laboratory of Molecular Genetics, Istituto Auxologico Italiano IRCCS, 20145 Milano, Italy; (S.M.); (A.M.D.B.)
| | - Anna M. Di Blasio
- Laboratory of Molecular Genetics, Istituto Auxologico Italiano IRCCS, 20145 Milano, Italy; (S.M.); (A.M.D.B.)
| | - Daniel Monleón
- Department of Pathology, Medicine and Odontology Faculty, University of Valencia, 46010 Valencia, Spain; (S.P.); (J.M.M.)
- Clinical Hospital Research Foundation-INCLIVA and CIBERFES, 46010 Valencia, Spain
- Correspondence:
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Liu T, Ji RL, Tao YX. Naturally occurring mutations in G protein-coupled receptors associated with obesity and type 2 diabetes mellitus. Pharmacol Ther 2021; 234:108044. [PMID: 34822948 DOI: 10.1016/j.pharmthera.2021.108044] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 11/15/2021] [Accepted: 11/15/2021] [Indexed: 12/12/2022]
Abstract
G protein-coupled receptors (GPCRs) are the largest family of membrane receptors involved in the regulation of almost all known physiological processes. Dysfunctions of GPCR-mediated signaling have been shown to cause various diseases. The prevalence of obesity and type 2 diabetes mellitus (T2DM), two strongly associated disorders, is increasing worldwide, with tremendous economical and health burden. New safer and more efficacious drugs are required for successful weight reduction and T2DM treatment. Multiple GPCRs are involved in the regulation of energy and glucose homeostasis. Mutations in these GPCRs contribute to the development and progression of obesity and T2DM. Therefore, these receptors can be therapeutic targets for obesity and T2DM. Indeed some of these receptors, such as melanocortin-4 receptor and glucagon-like peptide 1 receptor, have provided important new drugs for treating obesity and T2DM. This review will focus on the naturally occurring mutations of several GPCRs associated with obesity and T2DM, especially incorporating recent large genomic data and insights from structure-function studies, providing leads for future investigations.
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Affiliation(s)
- Ting Liu
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, AL 36849, United States
| | - Ren-Lei Ji
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, AL 36849, United States
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, AL 36849, United States.
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Wang W, Lin YJ, Chen ZX, Guo DY. Identification and characterization of two novel melanocortin-3 receptor mutations in Chinese obese individuals. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166107. [PMID: 33621651 DOI: 10.1016/j.bbadis.2021.166107] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 01/31/2021] [Accepted: 02/17/2021] [Indexed: 11/17/2022]
Abstract
The melanocortin-3 receptor (MC3R) and melanocortin-4 receptor (MC4R), known as neural melanocortin receptors, have been implicated to be critical components of the hypothalamic leptin-melanocortin pathway and related to obesity pathogenesis. In contrast to extensive evidence from physiologic, biological, genetic studies demonstrating that MC4R is a critical regulator in obesity, whether MC3R mutation causes obesity is still controversial. In the present study, we screened for coding variants in the MC3R gene of 176 obese individuals (mean BMI 34.84 ± 0.19 kg/m2) and 170 lean controls (mean BMI 20.70 ± 0.08 kg/m2) to assess the prevalence of MC3R mutations in a Chinese cohort. Two novel mutations, A33D (c.C98 > A) and A259T (c.G775 > A), were identified in two subjects with morbid obesity, respectively. A259T was also identified in the carrier's sibling. In vitro functional studies showed that A33D was defective in the cAMP signaling pathway, whereas A259T MC3R had defective maximal binding and cAMP generation in response to NDP- and α-MSH, likely due to decreased cell surface expression. In addition, we showed that A33D and A259T were biased receptors and defect in constitutive activation of ERK1/2 signaling through MC3R might be a cause for morbid obesity. Our sequencing and co-segregation studies combined with comprehensive functional analysis demonstrated that A259T might be predisposing to obesity. Further investigations in larger cohorts will be needed in order to define this association and the specific phenotypic characteristics resulting from these mutations.
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Affiliation(s)
- Wei Wang
- Department of Clinical laboratory, Xiamen Huli Guoyu Clinic, Co., Ltd., 128 Hetongli Rd, Huli District, Xiamen 361000, China.
| | - Yue-Jun Lin
- Department of Clinical laboratory, Xiamen Huli Guoyu Clinic, Co., Ltd., 128 Hetongli Rd, Huli District, Xiamen 361000, China
| | - Zhao-Xia Chen
- Department of Clinical laboratory, Xiamen Huli Guoyu Clinic, Co., Ltd., 128 Hetongli Rd, Huli District, Xiamen 361000, China
| | - Dong-Yu Guo
- Department of Clinical laboratory, Xiamen Huli Guoyu Clinic, Co., Ltd., 128 Hetongli Rd, Huli District, Xiamen 361000, China.
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Xu P, Gao QL, Wang YJ, Guo CF, Tang MX, Liu SH, Deng A, Wang YX, Li YB, Zhang HQ. rs6127698 polymorphism in the MC3R gene and susceptibility to multifocal tuberculosis in southern Chinese Han population. INFECTION GENETICS AND EVOLUTION 2020; 82:104292. [PMID: 32240798 DOI: 10.1016/j.meegid.2020.104292] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 02/15/2020] [Accepted: 03/19/2020] [Indexed: 11/17/2022]
Abstract
OBJECTIVE To investigate the relationship between melanocortin-3 receptor (MC3R) gene polymorphism and tuberculosis (TB) susceptibility in Han population in southern China. METHODS A total of 341 patients with TB (173 with pulmonary TB and 168 with multifocal TB) and 359 healthy controls were enrolled. Genotyping was performed by PCR and DNA sequencing, and detection of protein was performed by western blot. RESULTS The distributions of genotype and allele frequencies of rs6127698 differed significantly between the pulmonary and multifocal TB groups, and between the multifocal TB and control groups. The GG genotype was significantly more common among multifocal TB patients than among pulmonary TB patients (P = .009) and those in the control group (P = .001) under the recessive model. GG+GT genotype was more common in multifocal TB than in pulmonary TB (P < .01) and control group (P < .01) under the dominant model. G allele was more common in multifocal TB than in pulmonary TB (P < .0167) and control group (P < .0167). Patients with multifocal TB had an increased expression of MC3R protein than healthy controls (P < .05). CONCLUSIONS In the southern Chinese Han population, the MC3R rs6127698 polymorphism, which accompanying an increased expression of MC3R protein,was associated with susceptibility to multifocal TB. Presence of the G allele increased the risk of developing multifocal TB.
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Affiliation(s)
- Peng Xu
- Department of Spine Surgery, Xiangya Spinal Surgery Center, Xiangya Hospital, Central South University, Changsha 410008, People's Republic of China
| | - Qi-le Gao
- Department of Spine Surgery, Xiangya Spinal Surgery Center, Xiangya Hospital, Central South University, Changsha 410008, People's Republic of China
| | - Yun-Jia Wang
- Department of Spine Surgery, Xiangya Spinal Surgery Center, Xiangya Hospital, Central South University, Changsha 410008, People's Republic of China.
| | - Chao-Feng Guo
- Department of Spine Surgery, Xiangya Spinal Surgery Center, Xiangya Hospital, Central South University, Changsha 410008, People's Republic of China
| | - Ming-Xing Tang
- Department of Spine Surgery, Xiangya Spinal Surgery Center, Xiangya Hospital, Central South University, Changsha 410008, People's Republic of China
| | - Shao-Hua Liu
- Department of Spine Surgery, Xiangya Spinal Surgery Center, Xiangya Hospital, Central South University, Changsha 410008, People's Republic of China
| | - Ang Deng
- Department of Spine Surgery, Xiangya Spinal Surgery Center, Xiangya Hospital, Central South University, Changsha 410008, People's Republic of China
| | - Yu-Xiang Wang
- Department of Spine Surgery, Xiangya Spinal Surgery Center, Xiangya Hospital, Central South University, Changsha 410008, People's Republic of China
| | - Yan-Bing Li
- Department of Clinical Laboratory, Xiangya Hospital, Central South University, Changsha 410008, People's Republic of China
| | - Hong-Qi Zhang
- Department of Spine Surgery, Xiangya Spinal Surgery Center, Xiangya Hospital, Central South University, Changsha 410008, People's Republic of China
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Yu H, Chhabra KH, Thompson Z, Jones GL, Kiran S, Shangguan G, Low MJ. Hypothalamic POMC deficiency increases circulating adiponectin despite obesity. Mol Metab 2020; 35:100957. [PMID: 32244188 PMCID: PMC7082555 DOI: 10.1016/j.molmet.2020.01.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 01/22/2020] [Accepted: 01/31/2020] [Indexed: 02/06/2023] Open
Abstract
Objective The steep rise in the prevalence of obesity and its related metabolic syndrome have become a major worldwide health concerns. Melanocortin peptides from hypothalamic arcuate nucleus (Arc) POMC neurons induce satiety to limit food intake. Consequently, Arc Pomc-deficient mice (ArcPomc−/−) exhibit hyperphagia and obesity. Previous studies demonstrated that the circulating levels of adiponectin, a protein abundantly produced and secreted by fat cells, negatively correlate with obesity in both rodents and humans. However, we found that ArcPomc−/− mice have increased circulating adiponectin levels despite obesity. Therefore, we investigated the physiological function and underlying mechanisms of hypothalamic POMC in regulating systemic adiponectin levels. Methods Circulating adiponectin was measured in obese ArcPomc−/− mice at ages 4–52 weeks. To determine whether increased adiponectin was a direct result of ArcPomc deficiency or a secondary effect of obesity, we examined plasma adiponectin levels in calorie-restricted mice with or without a history of obesity and in ArcPomc−/− mice before and after genetic restoration of Pomc expression in the hypothalamus. To delineate the mechanisms causing increased adiponectin in ArcPomc−/− mice, we determined sympathetic outflow to adipose tissue by assessing epinephrine, norepinephrine, and tyrosine hydroxylase protein levels and measured the circulating adiponectin in the mice after acute norepinephrine or propranolol treatments. In addition, adiponectin mRNA and protein levels were measured in discrete adipose tissue depots to ascertain which fat depots contributed the most to the high level of adiponectin in the ArcPomc−/− mice. Finally, we generated compound Adiopoq−/−:ArcPomc−/− mice and compared their growth, body composition, and glucose homeostasis to the individual knockout mouse strains and their wild-type controls. Results Obese ArcPomc−/− female mice had unexpectedly increased plasma adiponectin compared to wild-type siblings at all ages greater than 8 weeks. Despite chronic calorie restriction to achieve normal body weights, higher adiponectin levels persisted in the ArcPomc−/− female mice. Genetic restoration of Pomc expression in the Arc or acute treatment of the ArcPomc−/− female mice with melanotan II reduced adiponectin levels to control littermate values. The ArcPomc−/− mice had defective thermogenesis and decreased epinephrine, norepinephrine, and tyrosine hydroxylase protein levels in their fat pads, indicating reduced sympathetic outflow to adipose tissue. Injections of norepinephrine into the ArcPomc−/− female mice reduced circulating adiponectin levels, whereas injections of propranolol significantly increased adiponectin levels. Despite the beneficial effects of adiponectin on metabolism, the deletion of adiponectin alleles in the ArcPomc−/− mice did not exacerbate their metabolic abnormalities. Conclusion In summary, to the best of our knowledge, this study provides the first evidence that despite obesity, the ArcPomc−/− mouse model has high circulating adiponectin levels, which demonstrated that increased fat mass is not necessarily correlated with hypoadiponectinemia. Our investigation also found a previously unknown physiological pathway connecting POMC neurons via the sympathetic nervous system to circulating adiponectin, thereby shedding light on the biological regulation of adiponectin. Obese female hypothalamic-specific Pomc-deficient mice have unexpectedly elevated circulating adiponectin. Restoration of Pomc expression in the hypothalamus reduces plasma adiponectin. Low sympathetic output to subcutaneous fat depots in the Pomc-deficient mice contributes to high adiponectin levels. Deletion of adiponectin in hypothalamic-specific Pomc-deficient mice does not alter their metabolic phenotype.
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Affiliation(s)
- Hui Yu
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, 48105, USA.
| | - Kavaljit H Chhabra
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, 48105, USA; Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Zoe Thompson
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, 48105, USA
| | - Graham L Jones
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, USA
| | - Sylee Kiran
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, 48105, USA; School of Literature, Science, and Arts, University of Michigan, Ann Arbor, MI, USA
| | - Gary Shangguan
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, 48105, USA
| | - Malcolm J Low
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, 48105, USA; Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, USA
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Koerperich ZM, Ericson MD, Freeman KT, Speth RC, Pogozheva ID, Mosberg HI, Haskell-Luevano C. Incorporation of Agouti-Related Protein (AgRP) Human Single Nucleotide Polymorphisms (SNPs) in the AgRP-Derived Macrocyclic Scaffold c[Pro-Arg-Phe-Phe-Asn-Ala-Phe-dPro] Decreases Melanocortin-4 Receptor Antagonist Potency and Results in the Discovery of Melanocortin-5 Receptor Antagonists. J Med Chem 2020; 63:2194-2208. [PMID: 31845801 DOI: 10.1021/acs.jmedchem.9b00860] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
While the melanocortin receptors (MCRs) are known to be involved in numerous biological pathways, the potential roles of the MC5R have not been clearly elucidated in humans. Agouti-related protein (AgRP), an MC3R/MC4R antagonist and MC4R inverse agonist, contains an exposed β-hairpin loop composed of six residues (Arg-Phe-Phe-Asn-Ala-Phe) that is imperative for binding and function. Within this active loop of AgRP, four human missense polymorphisms were deposited into the NIH Variation Viewer database. These polymorphisms, Arg111Cys, Arg111His, Phe112Tyr, and Ala115Val (AgRP full-length numbering), were incorporated into the peptide macrocycles c[Pro1-Arg2-Phe3-Phe4-Xaa5-Ala6-Phe7-dPro8], where Xaa was Dap5 or Asn5, to explore the functional effects of these naturally occurring substitutions in a simplified AgRP scaffold. All peptides lowered potency at least 10-fold in a cAMP accumulation assay compared to the parent sequences at the MC4Rs. Compounds MDE 6-82-3c, ZMK 2-82, MDE 6-82-1c, ZMK 2-85, and ZMK 2-112 are also the first AgRP-based chemotypes that antagonize the MC5R.
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Affiliation(s)
- Zoe M Koerperich
- Department of Medicinal Chemistry and Institute for Translational Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Mark D Ericson
- Department of Medicinal Chemistry and Institute for Translational Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Katie T Freeman
- Department of Medicinal Chemistry and Institute for Translational Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Robert C Speth
- College of Pharmacy, Nova Southeastern University, Fort Lauderdale, Florida 33328-2018, United States.,College of Medicine, Georgetown University, Washington, D.C. 20057, United States
| | - Irina D Pogozheva
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Henry I Mosberg
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Carrie Haskell-Luevano
- Department of Medicinal Chemistry and Institute for Translational Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, United States
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9
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Ehtesham S, Qasim A, Meyre D. Loss-of-function mutations in the melanocortin-3 receptor gene confer risk for human obesity: A systematic review and meta-analysis. Obes Rev 2019; 20:1085-1092. [PMID: 31090190 DOI: 10.1111/obr.12864] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/01/2019] [Revised: 03/20/2019] [Accepted: 03/21/2019] [Indexed: 02/06/2023]
Abstract
The association between rare coding loss-of-function (LOF) mutations in the melanocortin receptor 3 (MC3R) gene and human obesity is controversial. To fill this gap of knowledge, we performed a systematic review and meta-analysis of genetic association studies in all ages and ethnicities. Two reviewers independently performed risk of bias assessment and extracted data. We searched Medline, Embase, Web of Science Core Collection, BIOSIS Preview, CINAHL, ProQuest Dissertations & Theses, and reference lists of relevant studies. All case-control, cross-sectional, prospective, and retrospective studies that evaluated prevalence of rare (less than 1% frequency) coding partial/complete LOF mutations in MC3R among individuals with obesity and normal weight were included. Our systematic search identified 1925 references relevant to the present review. Six studies were deemed eligible. Meta-analysis of 2969 individuals with obesity and 2572 with normal weight showed a positive association between rare heterozygous coding partial/complete LOF mutations in MC3R and obesity in children and adults of European, North African, and Asian ancestries (odds ratio = 3.07; 95% CI, 1.48-7.00; P = 4.2 × 10-3 ). Our data demonstrates that rare partial/complete LOF mutations in the coding region of MC3R confer three-time increased risk of obesity in humans, and implies that rare genetic variants with intermediate effects contribute to the missing heritability of obesity.
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Affiliation(s)
- Sahar Ehtesham
- Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Ontario, Canada
| | - Anila Qasim
- Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Ontario, Canada
| | - David Meyre
- Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Ontario, Canada.,Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
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10
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Yuan XC, Tao YX. Fenoprofen-An Old Drug Rediscovered as a Biased Allosteric Enhancer for Melanocortin Receptors. ACS Chem Neurosci 2019; 10:1066-1074. [PMID: 30168706 DOI: 10.1021/acschemneuro.8b00347] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
It is time-consuming and costly to bring new drugs to market, making it necessary and urgent to exploit existing drugs for new uses. Recently, fenoprofen was demonstrated as an allosteric modulator at melanocortin receptors (MCRs), although the exact mode of action has not been clarified. MCRs regulate multiple functions, including pigmentation, adrenal steroidogenesis, inflammation, energy homeostasis, and exocrine gland secretion. In this study, we showed that fenoprofen failed to displace the orthosteric agonist Nle4-d-Phe7-α-melanocyte stimulating hormone from binding to MC3-5R while possessing positive allosteric modulator activities at these receptors. In addition, fenoprofen induced biased signaling at MC3-5R, as it selectively activated ERK1/2 cascade but not the canonical cAMP signaling. Notably, fenoprofen stimulated biased signaling at MC3-5R, but not at MC1R, hence acting selectively among this highly conserved family of receptors. Moreover, PAM activity and biased signaling induced by fenoprofen were observed not only at wild-type but also at naturally occurring mutant MC3Rs, suggesting that this biased allosteric enhancer action might constitute as novel therapeutic opportunity for obese patients harboring these mutations. Our study might guide novel therapeutic applications for repurposing current drugs or designing new drugs combining allosteric and biased properties.
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Affiliation(s)
- Xiao-Chen Yuan
- College of Animal Science and Technology, Anhui Agricultural University, Hefei, 230036 Anhui, China
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, Alabama 36849, United States
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, Alabama 36849, United States
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11
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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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12
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Singh RK, Kumar P, Mahalingam K. Molecular genetics of human obesity: A comprehensive review. C R Biol 2017; 340:87-108. [PMID: 28089486 DOI: 10.1016/j.crvi.2016.11.007] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 10/03/2016] [Accepted: 11/10/2016] [Indexed: 12/25/2022]
Abstract
Obesity and its related health complications is a major problem worldwide. Hypothalamus and their signalling molecules play a critical role in the intervening and coordination with energy balance and homeostasis. Genetic factors play a crucial role in determining an individual's predisposition to the weight gain and being obese. In the past few years, several genetic variants were identified as monogenic forms of human obesity having success over common polygenic forms. In the context of molecular genetics, genome-wide association studies (GWAS) approach and their findings signified a number of genetic variants predisposing to obesity. However, the last couple of years, it has also been noticed that alterations in the environmental and epigenetic factors are one of the key causes of obesity. Hence, this review might be helpful in the current scenario of molecular genetics of human obesity, obesity-related health complications (ORHC), and energy homeostasis. Future work based on the clinical discoveries may play a role in the molecular dissection of genetic approaches to find more obesity-susceptible gene loci.
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Affiliation(s)
- Rajan Kumar Singh
- Department of Bio-Medical Sciences, School of Biosciences and Technology, VIT University, 632014 Vellore, India
| | - Permendra Kumar
- Department of Bio-Medical Sciences, School of Biosciences and Technology, VIT University, 632014 Vellore, India
| | - Kulandaivelu Mahalingam
- Department of Bio-Medical Sciences, School of Biosciences and Technology, VIT University, 632014 Vellore, India.
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13
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Aris IM, Tint MT, Teh AL, Holbrook JD, Quah PL, Chong MF, Lin X, Soh SE, Saw S, Kwek K, Godfrey KM, Gluckman PD, Chong YS, Lek N, Yap F, Lee YS. MC3R gene polymorphisms are associated with early childhood adiposity gain and infant appetite in an Asian population. Pediatr Obes 2016; 11:450-458. [PMID: 26663875 PMCID: PMC5111755 DOI: 10.1111/ijpo.12086] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 10/17/2015] [Accepted: 10/24/2015] [Indexed: 02/04/2023]
Abstract
BACKGROUND Polymorphic variants within human melanocortin-3 receptor gene (MC3R) gene have been associated with obesity. However, its influence on infancy and early childhood adiposity has not been reported before. OBJECTIVES We assessed associations between genotype at polymorphic sites within MC3R with early childhood adiposity and interaction with early childhood appetitive traits. METHODS We studied 1090 singletons in an Asian mother-offspring cohort genotyped for MC3R and in a subgroup (n = 422) who had completed Child Eating Behaviour Questionnaires (CEBQ) at 12 months. Children were followed from birth to 48 months, and up to 10 measurements of body mass index and five measures of triceps and subscapular skin-folds were obtained. RESULTS Independent of potential confounders, each additional MC3R minor allele copy was associated with greater body mass index standard deviation score [B{95% confidence interval}: 0.004 units/month {0.001,0.007}; p = 0.007], triceps [0.009 mm/month {0.001,0.02}; p = 0.021] and subscapular skin-fold [0.008 mm/month {0.002,0.01}; p = 0.011] gain velocity in the first 48 months. Each additional MC3R minor allele copy was also associated with increased odds of overweight [odds ratio {95% confidence interval}: 1.48{1.17-1.88}] and obesity [1.58{1.10-2.28}] in the first 48 months. Every additional copy of MC3R minor allele was positively associated with 'slowness-in-eating' appetitive trait [0.24{0.06,0.39}, p = 0.006]; however, the relationship between 'slowness-in-eating' with adiposity gain was not statistically significant. CONCLUSIONS Our findings support the role of MC3R genetic variants in adiposity gain during early childhood.
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Affiliation(s)
- I. M. Aris
- Singapore Institute for Clinical SciencesAgency for Science, Technology and ResearchSingapore
- Department of Paediatrics, Yong Loo Lin School of MedicineNational University of SingaporeSingapore
| | - M. T. Tint
- Department of Obstetrics and Gynaecology, Yong Loo Lin School of MedicineNational University of SingaporeSingapore
| | - A. L. Teh
- Singapore Institute for Clinical SciencesAgency for Science, Technology and ResearchSingapore
| | - J. D. Holbrook
- Singapore Institute for Clinical SciencesAgency for Science, Technology and ResearchSingapore
| | - P. L. Quah
- Singapore Institute for Clinical SciencesAgency for Science, Technology and ResearchSingapore
| | - M. F.‐F. Chong
- Singapore Institute for Clinical SciencesAgency for Science, Technology and ResearchSingapore
- Department of Paediatrics, Yong Loo Lin School of MedicineNational University of SingaporeSingapore
| | - X. Lin
- Singapore Institute for Clinical SciencesAgency for Science, Technology and ResearchSingapore
| | - S. E. Soh
- Singapore Institute for Clinical SciencesAgency for Science, Technology and ResearchSingapore
- Department of Paediatrics, Yong Loo Lin School of MedicineNational University of SingaporeSingapore
| | - S.‐M. Saw
- Saw Swee Hock School of Public HealthNational University of SingaporeSingapore
| | - K. Kwek
- Department of Maternal Fetal MedicineKK Women's and Children's HospitalSingapore
| | - K. M. Godfrey
- MRC Lifecourse Epidemiology Unit and NIHR Southampton Biomedical Research CentreUniversity of Southampton and University Hospital Southampton NHS Foundation TrustSouthamptonUK
| | - P. D. Gluckman
- Department of Paediatrics, Yong Loo Lin School of MedicineNational University of SingaporeSingapore
- Liggins InstituteUniversity of AucklandAucklandNew Zealand
| | - Y. S. Chong
- Department of Obstetrics and Gynaecology, Yong Loo Lin School of MedicineNational University of SingaporeSingapore
| | - N. Lek
- Department of PaediatricsKK Women's and Children's HospitalSingapore
| | - F. Yap
- Department of PaediatricsKK Women's and Children's HospitalSingapore
| | - Y. S. Lee
- Singapore Institute for Clinical SciencesAgency for Science, Technology and ResearchSingapore
- Department of Paediatrics, Yong Loo Lin School of MedicineNational University of SingaporeSingapore
- Khoo Teck Puat‐National University Children's Medical InstituteNational University Health SystemSingapore
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You P, Hu H, Chen Y, Zhao Y, Yang Y, Wang T, Xing R, Shao Y, Zhang W, Li D, Chen H, Liu M. Effects of Melanocortin 3 and 4 Receptor Deficiency on Energy Homeostasis in Rats. Sci Rep 2016; 6:34938. [PMID: 27713523 PMCID: PMC5054679 DOI: 10.1038/srep34938] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 09/20/2016] [Indexed: 01/08/2023] Open
Abstract
Melanocortin-3 and 4 receptors (MC3R and MC4R) can regulate energy homeostasis, but their respective roles especially the functions of MC3R need more exploration. Here Mc3r and Mc4r single and double knockout (DKO) rats were generated using CRISPR-Cas9 system. Metabolic phenotypes were examined and data were compared systematically. Mc3r KO rats displayed hypophagia and decreased body weight, while Mc4r KO and DKO exhibited hyperphagia and increased body weight. All three mutants showed increased white adipose tissue mass and adipocyte size. Interestingly, although Mc3r KO did not show a significant elevation in lipids as seen in Mc4r KO, DKO displayed even higher lipid levels than Mc4r KO. DKO also showed more severe glucose intolerance and hyperglycaemia than Mc4r KO. These data demonstrated MC3R deficiency caused a reduction of food intake and body weight, whereas at the same time exhibited additive effects on top of MC4R deficiency on lipid and glucose metabolism. This is the first phenotypic analysis and systematic comparison of Mc3r KO, Mc4r KO and DKO rats on a homogenous genetic background. These mutant rats will be important in defining the complicated signalling pathways of MC3R and MC4R. Both Mc4r KO and DKO are good models for obesity and diabetes research.
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Affiliation(s)
- Panpan You
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China
| | - Handan Hu
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China
| | - Yuting Chen
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China
| | - Yongliang Zhao
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China
| | - Yiqing Yang
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China
| | - Tongtong Wang
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China
| | - Roumei Xing
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China
| | - Yanjiao Shao
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China
| | - Wen Zhang
- School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Dali Li
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China
| | - Huaqing Chen
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China
| | - Mingyao Liu
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, Shanghai 200241, China.,Institute of Biosciences and Technology, Department of Molecular and Cellular Medicine, Texas A&M University Health Science Center, Houston, Texas 77030, USA
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15
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Yoshiuchi I. Evidence for natural selection at the melanocortin-3 receptor gene in European and African populations. Acta Diabetol 2016; 53:583-7. [PMID: 26909893 DOI: 10.1007/s00592-016-0846-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 02/04/2016] [Indexed: 10/22/2022]
Abstract
AIMS Obesity is increasing steadily in worldwide prevalence and is known to cause serious health problems in association with type 2 diabetes mellitus (T2DM), including hypertension, stroke, and cardiovascular diseases. According to the thrifty gene hypothesis, the natural selection of obesity-related genes is important during feast and famine because they control body weight and fat levels. Past human adaptations to environmental changes in food supply, lifestyle, and geography may have influenced the selection of genes associated with the metabolism of glucose, lipids, and energy. The melanocortin-3 receptor gene (MC3R) is associated with obesity, with MC3R-deficient mice showing increased fat mass. MC3R variations are also linked with childhood obesity and insulin resistance. Here, we aimed to uncover evidence of selection at MC3R. METHODS We performed a three-step method to detect selection at MC3R using HapMap population data. We used Wright's F statistics as a measure of population differentiation, the long-range haplotype test to identify extended haplotypes, and the integrated haplotype score (iHS) to detect selection at MC3R. RESULTS We observed high population differentiation between European and African populations at two MC3R childhood obesity- and insulin resistance-associated single-nucleotide polymorphisms (rs3746619 and rs3827103) using Wright's F statistics. The iHS revealed evidence of natural selection at MC3R. CONCLUSIONS These findings provide evidence for natural selection at MC3R. Further investigation is warranted into adaptive evolution at T2DM- and obesity-associated genes.
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Affiliation(s)
- Issei Yoshiuchi
- Departments of Genetics, Diabetes Mellitus, and Medicine, Yoshiuchi Medical Diabetes Institute, 2-16-41 Kamakurayama, Kamakura City, Kanagawa, 248-0031, Japan.
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16
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Mutations in Melanocortin-3 Receptor Gene and Human Obesity. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2016; 140:97-129. [DOI: 10.1016/bs.pmbts.2016.01.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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17
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Wang ZQ, Huang JS, Zhou JH, Shi L, Jiang XF, Tao YX. Pharmacologic analyses of four chicken melanocortin-4 receptor mutations. Domest Anim Endocrinol 2016; 54:68-75. [PMID: 26521202 DOI: 10.1016/j.domaniend.2015.06.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 05/12/2015] [Accepted: 06/24/2015] [Indexed: 10/23/2022]
Abstract
The melanocortin-4 receptor (MC4R) is a critical regulator of mammalian food intake and energy expenditure, with receptor activation resulting in decreased food intake and increased energy expenditure. Recently, studies on role of MC4R in regulation of food intake have been extended to other species, such as chicken. Functional study of mutant MC4Rs is important in proving the causal link between MC4R mutation and production traits. Herein, we cloned chicken MC4R (cMC4R) complementary DNA and generated 4 mutant cMC4Rs (Q18H, G21R, S76L, and L299P) by site-directed mutagenesis and measured their expression by flow cytometry. Pharmacologic characteristics were analyzed with binding and signaling assays using 3 agonists. We showed that G21R had decreased cell surface and total expression (P < 0.05), whereas the other 3 mutants had similar total and cell surface expression levels as wild-type cMC4R. The 4 mutants had either decreased (Q18H, G21R, S76L; P < 0.05) or no (L299P) binding to radiolabeled [Nle(4), D-Phe(7)]-α-melanocyte-stimulating hormone (MSH). In signaling assays, Q18H was constitutively active. Q18H, G21R, and S76L had decreased responses to α-MSH stimulation (P < 0.05). L299P had decreased basal and ligand-stimulated signaling (P < 0.01). Nle(4), D-Phe(7)-MSH was the most potent agonist for cMC4R and therefore would be better suited for further in vivo studies. We conclude that the cloned cMC4R was a functional receptor and provided detailed functional data for these mutations, contributing to a better understanding of cMC4R variants associated with production traits.
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Affiliation(s)
- Z-Q Wang
- College of Veterinary Medicine, Yangzhou University, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, People's Republic of China; Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA.
| | - J-S Huang
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA
| | - J-H Zhou
- College of Veterinary Medicine, Yangzhou University, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, People's Republic of China
| | - L Shi
- College of Veterinary Medicine, Yangzhou University, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, People's Republic of China
| | - X-F Jiang
- College of Veterinary Medicine, Yangzhou University, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, People's Republic of China
| | - Y-X Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA.
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18
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Abstract
The melanocortin-3 receptor (MC3R) is a member of the family A G protein-coupled receptors (GPCRs). The MC3R remains the most enigmatic of the melanocortin receptors with regard to its physiological functions, especially its role in energy homeostasis. The N/DPxxY motif and the eighth helix (helix 8) in the carboxyl terminus of GPCRs have been identified to be important for receptor expression, ligand binding, signal transduction and internalization. To gain a better understanding of the structure-function relationship of MC3R, we performed a systematic study of all 20 residues in this domain using alanine-scanning mutagenesis. We showed that although all mutants were expressed normally on the cell surface, eleven residues were important for ligand binding and one was indispensable for downstream cAMP generation. F347A showed constitutive activity in cAMP signaling while all the other mutants had normal basal activities. We studied the signaling capacity of nine mutants in the ERK1/2 signaling pathway. All of these mutants showed normal basal ERK1/2 phosphorylation levels. The pERK1/2 levels of six binding- or signaling-defective mutants were enhanced upon agonist stimulation. The unbalanced cAMP and pERK1/2 signaling pathways suggested the existence of biased signaling in MC3R mutants. In summary, we showed that the DPLIY motif and helix 8 was important for MC3R activation and signal transduction. Our data led to a better understanding of the structure-function relationship of MC3R.
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Affiliation(s)
- Zhao Yang
- Department of AnatomyPhysiology and Pharmacology, College of Veterinary Medicine, Auburn University, 212 Greene Hall, Auburn, Alabama 36849, USASchool of Applied Chemistry and Biological TechnologyShenzhen Polytechnic, Shenzhen 518055, China
| | - Zhi-Li Huang
- Department of AnatomyPhysiology and Pharmacology, College of Veterinary Medicine, Auburn University, 212 Greene Hall, Auburn, Alabama 36849, USASchool of Applied Chemistry and Biological TechnologyShenzhen Polytechnic, Shenzhen 518055, China Department of AnatomyPhysiology and Pharmacology, College of Veterinary Medicine, Auburn University, 212 Greene Hall, Auburn, Alabama 36849, USASchool of Applied Chemistry and Biological TechnologyShenzhen Polytechnic, Shenzhen 518055, China
| | - Ya-Xiong Tao
- Department of AnatomyPhysiology and Pharmacology, College of Veterinary Medicine, Auburn University, 212 Greene Hall, Auburn, Alabama 36849, USASchool of Applied Chemistry and Biological TechnologyShenzhen Polytechnic, Shenzhen 518055, China
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19
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Yang F, Huang H, Tao YX. Biased signaling in naturally occurring mutations in human melanocortin-3 receptor gene. Int J Biol Sci 2015; 11:423-33. [PMID: 25798062 PMCID: PMC4366641 DOI: 10.7150/ijbs.11032] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 01/21/2015] [Indexed: 12/17/2022] Open
Abstract
The melanocortin-3 receptor (MC3R) is primarily expressed in the hypothalamus and plays an important role in the regulation of energy homeostasis. Recently, some studies demonstrated that MC3R also signals through mitogen-activated protein kinases (MAPKs), especially extracellular signal-regulated kinases 1 and 2 (ERK1/2). ERK1/2 signaling is known to alter gene expression, potentially contributing to the prolonged action of melanocortins on energy homeostasis regulation. In the present study, we performed detailed functional studies on 8 novel naturally occurring MC3R mutations recently reported, and the effects of endogenous MC3R agonist, α-melanocyte stimulating hormone (MSH), on ERK1/2 signaling on all 22 naturally occurring MC3R mutations reported to date. We found that mutants D158Y and L299V were potential pathogenic causes to obesity. Four residues, F82, D158, L249 and L299, played critical roles in different aspects of MC3R function. α-MSH exhibited balanced activity in Gs-cAMP and ERK1/2 signaling pathways in 15 of the 22 mutant MC3Rs. The other 7 mutant MC3Rs were biased to either one of the signaling pathways. In summary, we provided novel data about the structure-function relationship of MC3R, identifying residues important for receptor function. We also demonstrated that some mutations exhibited biased signaling, preferentially activating one intracellular signaling pathway, adding a new layer of complexity to MC3R pharmacology.
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Affiliation(s)
- Fan Yang
- 1. Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, USA. ; 2. Current address: College of Life Sciences, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia 010018, China
| | - Hui Huang
- 1. Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, USA
| | - Ya-Xiong Tao
- 1. Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, USA
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20
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Tao YX, Conn PM. Chaperoning G protein-coupled receptors: from cell biology to therapeutics. Endocr Rev 2014; 35:602-47. [PMID: 24661201 PMCID: PMC4105357 DOI: 10.1210/er.2013-1121] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 03/14/2014] [Indexed: 12/13/2022]
Abstract
G protein-coupled receptors (GPCRs) are membrane proteins that traverse the plasma membrane seven times (hence, are also called 7TM receptors). The polytopic structure of GPCRs makes the folding of GPCRs difficult and complex. Indeed, many wild-type GPCRs are not folded optimally, and defects in folding are the most common cause of genetic diseases due to GPCR mutations. Both general and receptor-specific molecular chaperones aid the folding of GPCRs. Chemical chaperones have been shown to be able to correct the misfolding in mutant GPCRs, proving to be important tools for studying the structure-function relationship of GPCRs. However, their potential therapeutic value is very limited. Pharmacological chaperones (pharmacoperones) are potentially important novel therapeutics for treating genetic diseases caused by mutations in GPCR genes that resulted in misfolded mutant proteins. Pharmacoperones also increase cell surface expression of wild-type GPCRs; therefore, they could be used to treat diseases that do not harbor mutations in GPCRs. Recent studies have shown that indeed pharmacoperones work in both experimental animals and patients. High-throughput assays have been developed to identify new pharmacoperones that could be used as therapeutics for a number of endocrine and other genetic diseases.
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Affiliation(s)
- Ya-Xiong Tao
- Department of Anatomy, Physiology, and Pharmacology (Y.-X.T.), College of Veterinary Medicine, Auburn University, Auburn, Alabama 36849-5519; and Departments of Internal Medicine and Cell Biology (P.M.C.), Texas Tech University Health Science Center, Lubbock, Texas 79430-6252
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Park J, Sharma N, Cutting GR. Melanocortin 3 receptor has a 5' exon that directs translation of apically localized protein from the second in-frame ATG. Mol Endocrinol 2014; 28:1547-57. [PMID: 25051171 DOI: 10.1210/me.2014-1105] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Melanocortin-3 receptor (MC3R) is a canonical MSH receptor that plays an essential role in energy homeostasis. Variants in MC3R have been implicated in obesity in humans and mice. However, interpretation of the functional consequences of these variants is challenging because the translational start site of MC3R is unclear. Using 5' rapid amplification of cDNA ends, we discovered a novel upstream exon that extends the length of the 5' untranslated region (UTR) in MC3R without changing the open-reading frame. The full-length 5' UTR directs utilization of an evolutionarily conserved second in-frame ATG as the primary translation start site. MC3R synthesized from the second ATG is localized to apical membranes of polarized Madin-Darby canine kidney cells, consistent with its function as a cell surface mediator of melanocortin signaling. Expression of MC3R causes relocalization of melanocortin receptor accessory protein 2, an accessory factor for melanocortin-2 receptor, to the apical membrane, coincident with the location of MC3R. In contrast, protein synthesized from MC3R cDNAs lacking the 5' UTR displayed diffuse cytosolic distribution and has no effect on the distribution of melanocortin receptor accessory protein 2. Our findings demonstrate that a previously unannotated 5' exon directs translation of MC3R protein that localizes to apical membranes of polarized cells. Together, our work provides insight on the structure of human MC3R and reveals a new pathway for regulation of energy metabolism.
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Affiliation(s)
- Jeenah Park
- McKusick-Nathans Institute of Genetic Medicine (J.P., N.S., G.R.C.), Johns Hopkins University, Baltimore, Maryland 21218; and Department of Pediatrics (G.R.C.), Johns Hopkins University School of Medicine, Baltimore, Maryland 21287-3914
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Alsmadi O, Melhem M, Hebbar P, Thareja G, John SE, Alkayal F, Behbehani K, Thanaraj TA. Leptin in association with common variants of MC3R mediates hypertension. Am J Hypertens 2014; 27:973-81. [PMID: 24487982 DOI: 10.1093/ajh/hpt285] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Recent research illustrates the role of central melanocortin signaling and leptin in the regulation of arterial blood pressure in animal models. Unraveling the genetic basis of interactions between melanocortin and leptin in humans will provide new insight into the regulation of arterial pressure. METHOD Our study population consisted of 332 Kuwaiti natives. Polymorphisms from exons of leptin, MC3R, and MC4R genes were identified by Sanger sequencing. MC3R expression and leptin levels were determined. Linear regression models, adjusted for age, gender, antihypertensive medication, and body mass index, were used to perform statistical association tests. RESULTS We observed a significant association between the MC3R missense variant (rs3827103 [Val81 Ile]) and systolic blood pressure (SBP; P = 0.01, β = 4.9). The N-terminus variant (rs3746619 [Thr6→Lys]) is in linkage disequilibrium (r2 = 0.65) with the rs3827103 variant. The AA haplotype of rs3746619-rs3827103 is significantly associated with SBP (P = 0.005, β=5.03). Minor allele frequencies of these two variants in the Kuwaiti population are twice those seen in European population. In individuals who harbor these variants, we found that the plasma leptin levels were positively correlated with SBP and that the expression of MC3R was downregulated. Leptin levels correlated with obesity traits irrespective of the genotypes at the variant positions. CONCLUSION An increase in leptin levels is known to increase sympathetic nerve activity that, in turn, increases blood pressure. Thus, it is possible that the observed MC3R variants in association with leptin levels are involved in regulation of blood pressure in humans.
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Affiliation(s)
- Osama Alsmadi
- Dasman Genome Centre, Dasman Diabetes Institute, Kuwait
| | | | - Prashantha Hebbar
- Integrative Informatics Department, Dasman Diabetes Institute, Kuwait
| | - Gaurav Thareja
- Integrative Informatics Department, Dasman Diabetes Institute, Kuwait
| | - Sumi E John
- Integrative Informatics Department, Dasman Diabetes Institute, Kuwait
| | - Fadi Alkayal
- Dasman Genome Centre, Dasman Diabetes Institute, Kuwait
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Gragnoli C. Hypothesis of the neuroendocrine cortisol pathway gene role in the comorbidity of depression, type 2 diabetes, and metabolic syndrome. APPLICATION OF CLINICAL GENETICS 2014; 7:43-53. [PMID: 24817815 PMCID: PMC4012344 DOI: 10.2147/tacg.s39993] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Depression, type 2 diabetes (T2D), and metabolic syndrome (MetS) are often comorbid. Depression per se increases the risk for T2D by 60%. This risk is not accounted for by the use of antidepressant therapy. Stress causes hyperactivation of the hypothalamic–pituitary–adrenal (HPA) axis, by triggering the hypothalamic corticotropin-releasing hormone (CRH) secretion, which stimulates the anterior pituitary to release the adrenocorticotropin hormone (ACTH), which causes the adrenal secretion of cortisol. Depression is associated with an increased level of cortisol, and CRH and ACTH at inappropriately “normal” levels, that is too high compared to their expected lower levels due to cortisol negative feedback. T2D and MetS are also associated with hypercortisolism. High levels of cortisol can impair mood as well as cause hyperglycemia and insulin resistance and other traits typical of T2D and MetS. We hypothesize that HPA axis hyperactivation may be due to variants in the genes of the CRH receptors (CRHR1, CRHR2), corticotropin receptors (or melanocortin receptors, MC1R-MC5R), glucocorticoid receptor (NR3C1), mineralocorticoid receptor (NR3C2), and of the FK506 binding protein 51 (FKBP5), and that these variants may be partially responsible for the clinical association of depression, T2D and MetS. In this review, we will focus on the correlation of stress, HPA axis hyperactivation, and the possible genetic role of the CRHR1, CRHR2, MCR1–5, NR3C1, and NR3C2 receptors and FKBP5 in the susceptibility to the comorbidity of depression, T2D, and MetS. New studies are needed to confirm the hypothesized role of these genes in the clinical association of depression, T2D, and MetS.
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Affiliation(s)
- Claudia Gragnoli
- Center for Biotechnology and Department of Biology, College of Science and Technology, Temple University, Philadelphia, PA, USA ; Molecular Biology Laboratory, Bios Biotech Multi-Diagnostic Health Center, Rome, Italy
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Common polymorphism (81Val>Ile) and rare mutations (257Arg>Ser and 335Ile>Ser) of the MC3R gene in obese Polish children and adolescents. Mol Biol Rep 2013; 40:6893-8. [PMID: 24142065 PMCID: PMC3835951 DOI: 10.1007/s11033-013-2808-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Accepted: 10/12/2013] [Indexed: 01/11/2023]
Abstract
The predisposing role to human obesity of the MC3R gene polymorphism is controversial. In this report we present the first study focused on the search for the MC3R polymorphism in the Polish population. Altogether 257 obese children and adolescents (RBMI>120) and 94 adults, who were never obese or overweight (BMI<25), were studied. For all subjects the entire coding sequence was analyzed by direct DNA sequencing. One common polymorphism (81Val>Ile) and two rare mutations (257Arg>Ser and 335Ile>Ser) were identified. The common polymorphism was widely distributed in the obese and control cohorts, while the mutations were identified in four obese subjects only. In case of the 335Ile>Ser substitution a three-generation family, consisting of 20 members, was also analyzed. It was found that all carriers of the 335Ser mutation were obese, but among non-carriers obese subjects also were found. Our study suggests that the predisposing effect to obesity of the 81Ile polymorphic variant is rather unlikely. With regard to the studied rare mutations we suggest that the 335Ser allele may have a small predisposing effect.
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Zegers D, Beckers S, Hendrickx R, Van Camp JK, Van Hoorenbeeck K, Desager KN, Massa G, Van Gaal LF, Van Hul W. Prevalence of rare MC3R variants in obese cases and lean controls. Endocrine 2013; 44:386-90. [PMID: 23264184 DOI: 10.1007/s12020-012-9862-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 12/12/2012] [Indexed: 01/13/2023]
Abstract
The role of mutations in the melanocortin-3 receptor (MC3R) gene, which is implicated in the regulation of energy homeostasis, is still under debate. Animal studies have clearly proven that, together with the melanocortin-4 receptor (MC4R), the MC3R is a critical receptor for melanocortin peptides within the leptin-melanocortin signaling cascade. However, as several mutations have been found in lean individuals and not all mutations seem to cause receptor dysfunction, results from mutation screens in obese humans remain controversial. In the present study, we screened for rare variants in the MC3R gene of obese children and lean controls to assess the prevalence of MC3R mutations in the Belgian population. We screened 249 severely overweight and obese children and adolescents and 239 lean adults for mutations in the coding region of MC3R. Mutation screening was performed by high resolution melting curve analysis and direct sequencing. We identified four non-synonymous coding variations in the obese population, all of which had been reported previously. In addition, we also found four novel rare MC3R variants in the lean control population, suggesting that not all MC3R mutations are disease-causing. Overall, the total prevalence of rare MC3R variants was 1 % in Belgian obese children and adolescents compared to 1.02 % in lean controls. Ultimately, cosegregation studies combined with comprehensive functional analysis is required to determine the potential pathogenic role of rare MC3R variants in causing human obesity.
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Affiliation(s)
- Doreen Zegers
- Department of Medical Genetics, University of Antwerp, Universiteitsplein 1, B-2610, Antwerp, Belgium
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Girardet C, Butler AA. Neural melanocortin receptors in obesity and related metabolic disorders. Biochim Biophys Acta Mol Basis Dis 2013; 1842:482-94. [PMID: 23680515 DOI: 10.1016/j.bbadis.2013.05.004] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 04/16/2013] [Accepted: 05/03/2013] [Indexed: 12/11/2022]
Abstract
Obesity is a global health issue, as it is associated with increased risk of developing chronic conditions associated with disorders of metabolism such as type 2 diabetes and cardiovascular disease. A better understanding of how excessive fat accumulation develops and causes diseases of the metabolic syndrome is urgently needed. The hypothalamic melanocortin system is an important point of convergence connecting signals of metabolic status with the neural circuitry that governs appetite and the autonomic and neuroendocrine system controling metabolism. This system has a critical role in the defense of body weight and maintenance of homeostasis. Two neural melanocortin receptors, melanocortin 3 and 4 receptors (MC3R and MC4R), play crucial roles in the regulation of energy balance. Mutations in the MC4R gene are the most common cause of monogenic obesity in humans, and a large literature indicates a role in regulating both energy intake through the control of satiety and energy expenditure. In contrast, MC3Rs have a more subtle role in energy homeostasis. Results from our lab indicate an important role for MC3Rs in synchronizing rhythms in foraging behavior with caloric cues and maintaining metabolic homeostasis during periods of nutrient scarcity. However, while deletion of the Mc3r gene in mice alters nutrient partitioning to favor accumulation of fat mass no obvious role for MC3R haploinsufficiency in human obesity has been reported. This article is part of a Special Issue entitled: Modulation of Adipose Tissue in Health and Disease.
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MESH Headings
- Animals
- Body Weight/genetics
- Cardiovascular Diseases/complications
- Cardiovascular Diseases/metabolism
- Cardiovascular Diseases/pathology
- Diabetes Mellitus, Type 2/complications
- Diabetes Mellitus, Type 2/metabolism
- Diabetes Mellitus, Type 2/pathology
- Humans
- Metabolic Diseases/genetics
- Metabolic Diseases/metabolism
- Metabolic Diseases/pathology
- Mice
- Obesity/complications
- Obesity/genetics
- Obesity/metabolism
- Obesity/pathology
- Receptor, Melanocortin, Type 3/genetics
- Receptor, Melanocortin, Type 3/metabolism
- Receptor, Melanocortin, Type 4/genetics
- Receptor, Melanocortin, Type 4/metabolism
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Affiliation(s)
- Clemence Girardet
- Department of Metabolism and Aging, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA
| | - Andrew A Butler
- Department of Metabolism and Aging, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA.
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Abstract
Disease-causing aberrations in the normal function of a gene define that gene as a disease gene. Proving a causal link between a gene and a disease experimentally is expensive and time-consuming. Comprehensive prioritization of candidate genes prior to experimental testing drastically reduces the associated costs. Computational gene prioritization is based on various pieces of correlative evidence that associate each gene with the given disease and suggest possible causal links. A fair amount of this evidence comes from high-throughput experimentation. Thus, well-developed methods are necessary to reliably deal with the quantity of information at hand. Existing gene prioritization techniques already significantly improve the outcomes of targeted experimental studies. Faster and more reliable techniques that account for novel data types are necessary for the development of new diagnostics, treatments, and cure for many diseases.
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Affiliation(s)
- Yana Bromberg
- Department of Biochemistry and Microbiology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, New Jersey, USA.
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Kay EI, Botha R, Montgomery JM, Mountjoy KG. hMRAPa increases αMSH-induced hMC1R and hMC3R functional coupling and hMC4R constitutive activity. J Mol Endocrinol 2013; 50:203-15. [PMID: 23296982 DOI: 10.1530/jme-12-0221] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Human melanocortin 2 receptor accessory protein (hMRAPa) is hypothesised to have functions beyond promoting human melanocortin 2 receptor (hMC2R) functional expression. To understand these potential functions, we exogenously co-expressed hMRAPa-FLAG with each of the five hMCR subtypes in HEK293 cells and assessed hMCR subtype coupling to adenylyl cyclase. We also co-expressed each HA-hMCR subtype with hMRAPa-FLAG to investigate their subcellular localisation. hMRAPa-FLAG enhanced α-melanocyte stimulating hormone (α-MSH)-stimulated hMC1R and hMC3R but reduced NDP-α-MSH-stimulated hMC5R, maximum coupling to adenylyl cyclase. hMRAPa-FLAG specifically increased hMC4R constitutive coupling to adenylyl cyclase despite not co-localising with the HA-hMC4R in the cell membrane. hMRAPa-FLAG co-localised with HA-hMC1R or HA-hMC3R in the perinuclear region, in cytoplasmic vesicles and at the plasma membrane, while it co-localised with HA-hMC2R, HA-hMC4R and HA-hMC5R predominantly in cytoplasmic vesicles. These diverse effects of hMRAPa indicate that hMRAPa could be an important modulator of the central and peripheral melanocortin systems if hMRAPa and any hMCR subtype co-express in the same cell.
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Affiliation(s)
- Emma I Kay
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1142, New Zealand
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29
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Mercer AJ, Hentges ST, Meshul CK, Low MJ. Unraveling the central proopiomelanocortin neural circuits. Front Neurosci 2013; 7:19. [PMID: 23440036 PMCID: PMC3579188 DOI: 10.3389/fnins.2013.00019] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Accepted: 02/04/2013] [Indexed: 11/16/2022] Open
Abstract
Central proopiomelanocortin (POMC) neurons form a potent anorexigenic network, but our understanding of the integration of this hypothalamic circuit throughout the central nervous system (CNS) remains incomplete. POMC neurons extend projections along the rostrocaudal axis of the brain, and can signal with both POMC-derived peptides and fast amino acid neurotransmitters. Although recent experimental advances in circuit-level manipulation have been applied to POMC neurons, many pivotal questions still remain: how and where do POMC neurons integrate metabolic information? Under what conditions do POMC neurons release bioactive molecules throughout the CNS? Are GABA and glutamate or neuropeptides released from POMC neurons more crucial for modulating feeding and metabolism? Resolving the exact stoichiometry of signals evoked from POMC neurons under different metabolic conditions therefore remains an ongoing endeavor. In this review, we analyze the anatomical atlas of this network juxtaposed to the physiological signaling of POMC neurons both in vitro and in vivo. We also consider novel genetic tools to further characterize the function of the POMC circuit in vivo. Our goal is to synthesize a global view of the POMC network, and to highlight gaps that require further research to expand our knowledge on how these neurons modulate energy balance.
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Affiliation(s)
- Aaron J Mercer
- Department of Molecular and Integrative Physiology, University of Michigan Ann Arbor, MI, USA
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30
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Yang F, Tao YX. Functional characterization of nine novel naturally occurring human melanocortin-3 receptor mutations. Biochim Biophys Acta Mol Basis Dis 2012; 1822:1752-61. [PMID: 22884546 DOI: 10.1016/j.bbadis.2012.07.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2012] [Revised: 07/12/2012] [Accepted: 07/27/2012] [Indexed: 12/20/2022]
Abstract
The melanocortin-3 receptor (MC3R) is a member of family A rhodopsin-like G protein-coupled receptors. Mouse genetic studies suggested that MC3R and the related MC4R are non-redundant regulators of energy homeostasis. Lack of Mc3r leads to higher feed efficiency and fat mass. However, until now only a few MC3R mutations have been identified in humans and the role of MC3R in the pathogenesis of obesity was unclear. In the present study, we performed detailed functional studies on nine naturally occurring MC3R mutations recently reported. We found that all nine mutants had decreased cell surface expression. A260V, M275T, and L297V had decreased total expression whereas the other six mutants had normal total expression. Mutants S69C and T280S exhibited significant defects in ligand binding and signaling. The dramatic defects of T280S might be partially caused by decreased cell surface expression. In addition, we found mutants M134I and M275T had decreased maximal binding but displayed similar signaling properties as wild-type MC3R. All the other mutants had normal binding and signaling activities. Co-expression studies showed that all mutants except L297V did not affect wild-type MC3R signaling. Multiple mutations at T280 demonstrated the necessity of Thr for cell surface expression, ligand binding, and signaling. In summary, we provided detailed data of these novel human MC3R mutations leading to a better understanding of structure-function relationship of MC3R and the role of MC3R mutation in obesity.
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Affiliation(s)
- Fan Yang
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA
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31
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Biebermann H, Kühnen P, Kleinau G, Krude H. The neuroendocrine circuitry controlled by POMC, MSH, and AGRP. Handb Exp Pharmacol 2012:47-75. [PMID: 22249810 DOI: 10.1007/978-3-642-24716-3_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Obesity is one of the most challenging health problems worldwide. Over the past few decades, our knowledge concerning mechanisms of weight regulation has increased tremendously leading to the identification of the leptin-melanocortin pathway. The filling level of energy stores is signaled to the brain, and the information is integrated by hypothalamic nuclei, resulting in a well-orchestrated response to food intake and energy expenditure to ensure constant body weight. One of the key players in this system is proopiomelanocortin (POMC), a precursor of a variety of neuropeptides. POMC-derived alpha- and beta-MSH play an important role in energy homeostasis by activating melanocortin receptors expressed in the arcuate nucleus (MC3R) and in the nucleus paraventricularis (MC4R). Activation of these two G protein-coupled receptors is antagonized by agouti-related peptide (AgRP). Naturally occurring mutations in this system were identified in patients suffering from common obesity as well as in patients demonstrating a phenotype of severe early-onset obesity, adrenal insufficiency, red hair, and pale skin. Detailed understanding of the complex system of POMC-AgRP-MC3R-MC4R and their interaction with other hypothalamic as well as peripheral signals is a prerequisite to combat the obesity epidemic.
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Affiliation(s)
- Heike Biebermann
- Institut für Experimentelle Pädiatrische Endokrinologie, Charité Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
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Tarnow P, Rediger A, Schulz A, Grüters A, Biebermann H. Identification of the translation start site of the human melanocortin 3 receptor. Obes Facts 2012; 5:45-51. [PMID: 22433616 DOI: 10.1159/000336070] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 10/12/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The melanocortin-3-receptor (MC3R) is a G-protein coupled receptor participating in hypothalamic energy metabolism. So far, it was assumed that the translation of the human MC3R starts at the non-conserved first ATG, however, a second evolutionary conserved ATG is located 37 amino acids downstream. One frequent polymorphism, T6K, is located between these two ATGs. METHODS For characterization of the two potential start ATGs, COS-7 cells were transfected with plasmids encoding the longer and the shorter form of the human MC3R. For signal transduction properties, cAMP was measured. Cell surface expression was determined by using an ELISA method. The translational start point of the MC3R was investigated by a GFP-based method. RESULTS Signal transduction was comparable for the long and the short receptor form. Cell surface expression via aminoterminal hemagglutinin tag could only be detected in the shorter form, but not in the longer one. In our study we show that the translation of the human MC3R protein starts at the evolutionary conserved ATG codon which results in a shorter protein than previously assumed. CONCLUSION The polymorphism T6K is not located in the coding region of the human MC3R and has no influence on translation initiation which makes an impact on body weight unlikely.
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Affiliation(s)
- Patrick Tarnow
- Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, Humboldt University, Augustenburger Platz 1, Berlin, Germany
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Wang ZQ, Tao YX. Functional studies on twenty novel naturally occurring melanocortin-4 receptor mutations. Biochim Biophys Acta Mol Basis Dis 2011; 1812:1190-9. [PMID: 21729752 DOI: 10.1016/j.bbadis.2011.06.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Revised: 06/08/2011] [Accepted: 06/21/2011] [Indexed: 11/27/2022]
Abstract
The melanocortin-4 receptor (MC4R) is a G protein-coupled receptor critically involved in regulating energy balance. MC4R activation results in decreased food intake and increased energy expenditure. Genetic and pharmacological studies demonstrated that the MC4R regulation of energy balance is conserved from fish to mammals. In humans, more than 150 naturally occurring mutations in the MC4R gene have been identified. Functional study of mutant MC4Rs is an important component in proving the causal link between MC4R mutation and obesity as well as the basis of personalized medicine. In this article, we studied 20 MC4R mutations that were either not characterized or not fully characterized. We showed that 11 mutants had decreased or absent cell surface expression. D126Y was defective in ligand binding. Three mutants were constitutively active but had decreased cell surface expression. Eleven mutants had decreased basal signaling, with two mutants defective only in this parameter, suggesting that impaired basal signaling might also be a cause of obesity. Five mutants had normal functions. In summary, we provided detailed functional data for further studies on identifying therapeutic approaches for personalized medicine to treat patients harboring these mutations.
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Affiliation(s)
- Zhi-Qiang Wang
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, People's Republic of China
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Santos JL, De la Cruz R, Holst C, Grau K, Naranjo C, Maiz A, Astrup A, Saris WHM, MacDonald I, Oppert JM, Hansen T, Pedersen O, Sorensen TIA, Martinez JA. Allelic variants of melanocortin 3 receptor gene (MC3R) and weight loss in obesity: a randomised trial of hypo-energetic high- versus low-fat diets. PLoS One 2011; 6:e19934. [PMID: 21695122 PMCID: PMC3114803 DOI: 10.1371/journal.pone.0019934] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Accepted: 04/21/2011] [Indexed: 11/29/2022] Open
Abstract
Introduction The melanocortin system plays an important role in energy homeostasis. Mice genetically deficient in the melanocortin-3 receptor gene have a normal body weight with increased body fat, mild hypophagia compared to wild-type mice. In humans, Thr6Lys and Val81Ile variants of the melanocortin-3 receptor gene (MC3R) have been associated with childhood obesity, higher BMI Z-score and elevated body fat percentage compared to non-carriers. The aim of this study is to assess the association in adults between allelic variants of MC3R with weight loss induced by energy-restricted diets. Subjects and Methods This research is based on the NUGENOB study, a trial conducted to assess weight loss during a 10-week dietary intervention involving two different hypo-energetic (high-fat and low-fat) diets. A total of 760 obese patients were genotyped for 10 single nucleotide polymorphisms covering the single exon of MC3R gene and its flanking regions, including the missense variants Thr6Lys and Val81Ile. Linear mixed models and haplotype-based analysis were carried out to assess the potential association between genetic polymorphisms and differential weight loss, fat mass loss, waist change and resting energy expenditure changes. Results No differences in drop-out rate were found by MC3R genotypes. The rs6014646 polymorphism was significantly associated with weight loss using co-dominant (p = 0.04) and dominant models (p = 0.03). These p-values were not statistically significant after strict control for multiple testing. Haplotype-based multivariate analysis using permutations showed that rs3827103–rs1543873 (p = 0.06), rs6014646–rs6024730 (p = 0.05) and rs3746619–rs3827103 (p = 0.10) displayed near-statistical significant results in relation to weight loss. No other significant associations or gene*diet interactions were detected for weight loss, fat mass loss, waist change and resting energy expenditure changes. Conclusion The study provided overall sufficient evidence to support that there is no major effect of genetic variants of MC3R and differential weight loss after a 10-week dietary intervention with hypo-energetic diets in obese Europeans.
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Affiliation(s)
- José L. Santos
- Department of Nutrition, Diabetes and Metabolism, Pontificia Universidad Católica de Chile, Santiago, Chile
- Department of Nutrition and Food Sciences, Physiology and Toxicology, University of Navarra, Pamplona, Spain
| | - Rolando De la Cruz
- Department of Public Health and Department of Statistics, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Claus Holst
- Centre for Health and Society, Institute of Preventive Medicine, Copenhagen University Hospital, Copenhagen, Denmark
| | - Katrine Grau
- Centre for Health and Society, Institute of Preventive Medicine, Copenhagen University Hospital, Copenhagen, Denmark
| | - Carolina Naranjo
- Department of Public Health and Department of Statistics, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Alberto Maiz
- Department of Nutrition, Diabetes and Metabolism, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Arne Astrup
- Department of Human Nutrition, Faculty of Life Science, University of Copenhagen, Copenhagen, Denmark
| | - Wim H. M. Saris
- Department of Human Biology, Nutrition and Toxicology Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Ian MacDonald
- School of Biomedical Science, University of Nottingham Medical School, Queen's Medical Centre, Nottingham, United Kingdom
| | - Jean-Michel Oppert
- Department of Nutrition, Hotel-Dieu Hospital University Pierre-et-Marie Curie (Paris 6), Human Nutrition Research Center Ile-de-France, Paris, France
| | | | - Oluf Pedersen
- Hagedorn Research Institute, Gentofte, Denmark
- Institute of Biomedical Science, University of Copenhagen, Copenhagen, Denmark
| | - Thorkild I. A. Sorensen
- Centre for Health and Society, Institute of Preventive Medicine, Copenhagen University Hospital, Copenhagen, Denmark
| | - J. Alfredo Martinez
- Department of Nutrition and Food Sciences, Physiology and Toxicology, University of Navarra, Pamplona, Spain
- * E-mail:
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Polymorphisms in MC3R promoter and CTSZ 3'UTR are associated with tuberculosis susceptibility. Eur J Hum Genet 2011; 19:676-81. [PMID: 21368909 DOI: 10.1038/ejhg.2011.1] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
We have validated the association of two genes on chromosome 20q13.31-33 with tuberculosis susceptibility. A previous genome-wide linkage study performed by Cooke et al identified the genes melanocortin-3-receptor (MC3R) and cathepsin Z (CTSZ) as possible candidates in tuberculosis susceptibility. MC3R has been implicated in obesity studies and is known to play a role in many biological systems including the regulation of energy homeostasis and fat metabolism. CTSZ has been detected in immune cells, such as macrophages and monocytes, and it is hypothesized that the protein may play a role in the immune response. In our South African population a case-control study confirmed the previously reported association with a single-nucleotide polymorphism (SNP) in CTSZ and found an association in MC3R with a SNP not previously implicated in tuberculosis susceptibility. Six SNPs in MC3R and eight in CTSZ were genotyped and haplotypes were inferred. SNP rs6127698 in the promoter region of MC3R (cases = 498; controls = 506) and rs34069356 in the 3'UTR of CTSZ (cases = 396; controls = 298) both showed significant association with tuberculosis susceptibility (P = 0.0004 and < 0.0001, respectively), indicating that pathways involving these proteins, not previously researched in this disease, could yield novel therapies for tuberculosis.
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Physiological roles of the melanocortin MC₃ receptor. Eur J Pharmacol 2011; 660:13-20. [PMID: 21211527 DOI: 10.1016/j.ejphar.2010.12.025] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Revised: 12/11/2010] [Accepted: 12/15/2010] [Indexed: 11/23/2022]
Abstract
The melanocortin MC(3) receptor remains the most enigmatic of the melanocortin receptors with regard to its physiological functions. The receptor is expressed both in the CNS and in multiple tissues in the periphery. It appears to be an inhibitory autoreceptor on proopiomelanocortin neurons, yet global deletion of the receptor causes an obesity syndrome. Knockout of the receptor increases adipose mass without a readily measurable increase in food intake or decrease in energy expenditure. And finally, no melanocortin MC(3) receptor null humans have been identified and associations between variant alleles of the melanocortin MC(3) receptor and diseases remain controversial, so the physiological role of the receptor in humans remains to be determined.
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Zegers D, Beckers S, de Freitas F, Peeters AV, Mertens IL, Verhulst SL, Rooman RP, Timmermans JP, Desager KN, Massa G, Van Gaal LF, Van Hul W. Identification of three novel genetic variants in the melanocortin-3 receptor of obese children. Obesity (Silver Spring) 2011; 19:152-9. [PMID: 20539302 DOI: 10.1038/oby.2010.127] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The melanocortin-3 receptor (MC3R), a G-protein-coupled receptor expressed in the hypothalamus, is a key component of the leptin-melanocortin pathway that regulates energy homeostasis. It is suggested that an MC3R defect leads to an increased feed efficiency, by which nutrients are partitioned preferentially into fat. In this study, we hypothesized that early-onset obesity could be induced by mutations in MC3R. To investigate this hypothesis, we screened the entire coding region of the MC3R gene for mutations in obese subjects. A total of 404 overweight and obese children and adolescents, 86 severely obese adults (BMI ≥40 kg/m²), and 150 normal-weight control adults were included. Besides three synonymous coding variations in the MC3R gene (S69S, L95L, I226I), we were able to identify three novel heterozygous, nonsynonymous, coding mutations (N128S, V211I, L299V) in three unrelated obese children. None of these mutations were found in any of the control subjects. Functional studies assessing localization and signaling properties of the mutant receptors provided proof for impaired function of the L299V mutated receptor, whereas no conclusive evidence for functional impairment of the N128S and V211I mutated receptors could be established. First, these results provide supporting evidence for a role of the MC3R gene in the pathogenesis of obesity in a small subset of patients. Second, they show that caution is called for the interpretation of newly discovered mutations in MC3R.
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Affiliation(s)
- Doreen Zegers
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium
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Yako Y, Fanampe B, Hassan M, Erasmus R, van der Merwe L, van Rensburg S, Matsha T. Association of Cocaine- and Amphetamine-Related Transcript, Leptin and Leptin Receptor Gene Polymorphisms with Anthropometric Obesity Phenotype Indicators in South African Learners. JOURNAL OF NUTRIGENETICS AND NUTRIGENOMICS 2011; 4:210-21. [DOI: 10.1159/000329614] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Accepted: 05/25/2011] [Indexed: 11/19/2022]
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Mencarelli M, Dubern B, Alili R, Maestrini S, Benajiba L, Tagliaferri M, Galan P, Rinaldi M, Simon C, Tounian P, Hercberg S, Liuzzi A, Di Blasio AM, Clement K. Rare melanocortin-3 receptor mutations with in vitro functional consequences are associated with human obesity. Hum Mol Genet 2010; 20:392-9. [PMID: 21047972 DOI: 10.1093/hmg/ddq472] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
In contrast to the melanocortin 4 receptor, the possible role of the melanocortin 3 receptor (MC3R) in regulating body weight is still debated. We have previously reported three mutations in the MC3R gene showing association with human obesity, but these results were not confirmed in a study of severe obese North American adults. In this study, we evaluated the entire coding region of MC3R in 839 severely obese subjects and 967 lean controls of Italian and French origin. In vitro functional analysis of the mutations detected was also performed. The total prevalence of rare MC3R variants was not significantly different in obese subjects when compared with controls (P= 0.18). However, the prevalence of mutations with functional alterations was significantly higher in the obese group (P= 0.022). In conclusions, the results of this large study demonstrate that in the populations studied functionally significant MC3R variants are associated with obesity supporting the current hypothesis that rare variants might have a stronger impact on the individual susceptibility to gain weight. They also underline the importance of detailed in vitro functional studies in order to prove the pathogenic effect of such variants. Further investigations in larger cohorts will be needed in order to define the specific phenotypic characteristics potentially correlated with reduced MC3R signalling.
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Affiliation(s)
- Monica Mencarelli
- Molecular Biology Laboratory, Istituto Auxologico Italiano, Verbania, Italy
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40
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Zegers D, Beckers S, Mertens IL, Van Gaal LF, Van Hul W. Common melanocortin-3 receptor variants are not associated with obesity, although rs3746619 does influence weight in obese individuals. Endocrine 2010; 38:289-93. [PMID: 20972733 DOI: 10.1007/s12020-010-9386-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Accepted: 08/20/2010] [Indexed: 11/24/2022]
Abstract
The melanocortin-3 receptor is a vital link in the leptin-melanocortin signaling pathway in the brain and has a role in the regulation of energy homeostasis. It was hypothesized that common polymorphisms in MC3R could increase susceptibility for the development of obesity, but different studies have led to contradictory results. In this study, we investigated the association of SNPs in MC3R with the development of obesity in an extensive Caucasian population. Using the HapMap, we selected two tagSNPs (rs6127698 and rs3746619) that cover all of the common genetic variation in MC3R and genotyped them in 1008 obese cases and 313 normal weight controls. Statistical analysis of the data showed that none of the analyzed SNPs were associated with obesity. However, linear regression analysis did show that SNP rs3746619 has an influence on weight (P=0.015) in the obese population only. Furthermore, a trend for association with BMI in the obese population was observed for this SNP (P=0.039). Taken together, these data are consistent with the involvement of rs3746619 in weight regulation among obese individuals. However, further research including replication of our results is necessary to elucidate the role of MC3R in complex obesity.
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Affiliation(s)
- Doreen Zegers
- Department of Medical Genetics, University of Antwerp, Universiteitsplein 1, 2610, Antwerp, Belgium
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41
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Obregón A, Amador P, Valladares M, Weisstaub G, Burrows R, Santos J. Melanocortin-3 receptor gene variants: Association with childhood obesity and eating behavior in Chilean families. Nutrition 2010; 26:760-5. [DOI: 10.1016/j.nut.2009.07.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2009] [Revised: 05/29/2009] [Accepted: 07/01/2009] [Indexed: 10/19/2022]
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Abstract
Melanocortin peptides, derived from POMC (pro-opiomelanocortin) are produced in the ARH (arcuate nucleus of the hypothalamus) neurons and the neurons in the commissural NTS (nucleus of the solitary tract) of the brainstem, in anterior and intermediate lobes of the pituitary, skin and a wide range of peripheral tissues, including reproductive organs. A hypothetical model for functional roles of melanocortin receptors in maintaining energy balance was proposed in 1997. Since this time, there has been an extraordinary amount of knowledge gained about POMC-derived peptides in relation to energy homoeostasis. Development of a Pomc-null mouse provided definitive proof that POMC-derived peptides are critical for the regulation of energy homoeostasis. The melanocortin system consists of endogenous agonists and antagonists, five melanocortin receptor subtypes and receptor accessory proteins. The melanocortin system, as is now known, is far more complex than most of us could have imagined in 1997, and, similarly, the importance of this system for regulating energy homoeostasis in the general human population is much greater than we would have predicted. Of the known factors that can cause human obesity, or protect against it, the melanocortin system is by far the most significant. The present review is a discussion of the current understanding of the roles and mechanism of action of POMC, melanocortin receptors and AgRP (agouti-related peptide) in obesity and Type 2 diabetes and how the central and/or peripheral melanocortin systems mediate nutrient, leptin, insulin, gut hormone and cytokine regulation of energy homoeostasis.
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43
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Tao YX, Huang H, Wang ZQ, Yang F, Williams JN, Nikiforovich GV. Constitutive activity of neural melanocortin receptors. Methods Enzymol 2010; 484:267-79. [PMID: 21036237 DOI: 10.1016/b978-0-12-381298-8.00014-9] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
The two neural melanocortin receptors (MCRs), melanocortin-3 and -4 receptors (MC3R and MC4R), are G protein-coupled receptors expressed primarily in the brain that regulate different aspects of energy homeostasis. The MCRs are unique in having endogenous antagonists, agouti and agouti-related protein (AgRP). These antagonists were later shown to be inverse agonists. The MC3R has little or no constitutive activity, whereas the MC4R has significant constitutive activity that can easily be detected. We describe herein methods for detecting constitutive activities in these receptors and small molecule ligands as inverse agonists. AgRP is an inverse agonist for both MC3R and MC4R. We also provide models for the constitutively active MC4R mutants.
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Affiliation(s)
- Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, Alabama, USA
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44
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Garfield AS, Lam DD, Marston OJ, Przydzial MJ, Heisler LK. Role of central melanocortin pathways in energy homeostasis. Trends Endocrinol Metab 2009; 20:203-15. [PMID: 19541496 DOI: 10.1016/j.tem.2009.02.002] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Revised: 02/06/2009] [Accepted: 02/06/2009] [Indexed: 02/07/2023]
Abstract
The rise in the global prevalence of human obesity has emphasized the need for a greater understanding of the physiological mechanisms that underlie energy homeostasis. Numerous circulating nutritional cues and central neuromodulatory signals are integrated within the brain to regulate both short- and long-term nutritional state. The central melanocortin system represents a crucial point of convergence for these signals and, thus, has a fundamental role in regulating body weight. The melanocortin ligands, synthesized in discrete neuronal populations within the hypothalamus and brainstem, modulate downstream homeostatic signalling via their action at central melanocortin-3 and -4 receptors. Intimately involved in both ingestive behaviour and energy expenditure, the melanocortin system has garnered much interest as a potential therapeutic target for human obesity.
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Affiliation(s)
- Alastair S Garfield
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, UK
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45
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Lee YS. The Role of Leptin-Melanocortin System and Human Weight Regulation: Lessons from Experiments of Nature. ANNALS OF THE ACADEMY OF MEDICINE, SINGAPORE 2009. [DOI: 10.47102/annals-acadmedsg.v38n1p34] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Introduction: Common obesity is a multi-factorial trait, contributed by the “obesogenic” environment of caloric abundance and increasing automation, sedentary lifestyle and an underlying genetic susceptibility. There have been major advances in the past decade in our understanding of the human weight regulation mechanism and pathogenesis of obesity, abetted by discoveries of genetic defects which lead to human obesity.
Materials and Methods: Reports of genetic mutations causing obesity in humans and murine models were reviewed
Results: Humans with genetic defects resulting in leptin deficiency, leptin receptor deficiency, pro-opiomelanocortin deficiency (POMC), and melanocortin 4 receptor (MC4R) deficiency developed severe obesity as the dominant phenotypic feature, though these are rare autosomal recessive conditions, except MC4R deficiency which is inherited in an autosomal co-dominant fashion. Common and rare variants of the POMC and melanocortin 3 receptor genes may be pre-disposing factors in the development of common obesity. Recent reports of human obesity associated with thyrosine kinase B (TrkB) defect and brain derived neurotrophic factor (BDNF) disruption, coupled with other murine studies, supported the role of BDNF/TrkB as effectors downstream of the melanocortin receptors.
Conclusions: Despite exciting discoveries of single gene mutations resulting in human obesity, most cases of obesity are likely the result of subtle interactions of several related genetic variants with environmental factors which favour the net deposition of calories as fat, culminating in the obese phenotype. The mechanisms of action of these genes in the development of obesity are now being examined, with the aim of eventually discovering a therapeutic intervention for obesity.
Key words: Leptin, Melanocortin, Obesity
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47
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Calton MA, Ersoy BA, Zhang S, Kane JP, Malloy MJ, Pullinger CR, Bromberg Y, Pennacchio LA, Dent R, McPherson R, Ahituv N, Vaisse C. Association of functionally significant Melanocortin-4 but not Melanocortin-3 receptor mutations with severe adult obesity in a large North American case-control study. Hum Mol Genet 2008; 18:1140-7. [PMID: 19091795 DOI: 10.1093/hmg/ddn431] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Functionally significant heterozygous mutations in the Melanocortin-4 receptor (MC4R) have been implicated in 2.5% of early onset obesity cases in European cohorts. The role of mutations in this gene in severely obese adults, particularly in smaller North American patient cohorts, has been less convincing. More recently, it has been proposed that mutations in a phylogenetically and physiologically related receptor, the Melanocortin-3 receptor (MC3R), could also be a cause of severe human obesity. The objectives of this study were to determine if mutations impairing the function of MC4R or MC3R were associated with severe obesity in North American adults. We studied MC4R and MC3R mutations detected in a total of 1821 adults (889 severely obese and 932 lean controls) from two cohorts. We systematically and comparatively evaluated the functional consequences of all mutations found in both MC4R and MC3R. The total prevalence of rare MC4R variants in severely obese North American adults was 2.25% (CI(95%): 1.44-3.47) compared with 0.64% (CI(95%): 0.26-1.43) in lean controls (P < 0.005). After classification of functional consequence, the prevalence of MC4R mutations with functional alterations was significantly greater when compared with controls (P < 0.005). In contrast, the prevalence of rare MC3R variants was not significantly increased in severely obese adults [0.67% (CI(95%): 0.27-1.50) versus 0.32% (CI(95%): 0.06-0.99)] (P = 0.332). Our results confirm that mutations in MC4R are a significant cause of severe obesity, extending this finding to North American adults. However, our data suggest that MC3R mutations are not associated with severe obesity in this population.
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Affiliation(s)
- Melissa A Calton
- Diabetes Center, University of California San Francisco, San Francisco, CA 94143, USA
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48
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Wang SX, Fan ZC, Tao YX. Functions of acidic transmembrane residues in human melanocortin-3 receptor binding and activation. Biochem Pharmacol 2008; 76:520-30. [PMID: 18614155 DOI: 10.1016/j.bcp.2008.05.026] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Revised: 05/22/2008] [Accepted: 05/23/2008] [Indexed: 10/22/2022]
Abstract
The melanocortin-3 receptor (MC3R) is an important regulator of energy homeostasis, inflammation, and cardiovascular function. Inactivating mutations in MC3R gene are associated with childhood obesity. How MC3R binds to its ligands has rarely been studied. In the present study, we systematically mutated all ten acidic residues in transmembrane (TM) domains and measured the cell surface expression levels as well as ligand binding and signaling properties of these mutants. Our results showed that of the 19 mutants stably expressed in HEK293 cells, all were expressed on the cell surface, although some mutants had decreased levels of cell surface expression. We showed that with the superpotent analog [Nle(4), D-Phe(7)]-alpha-melanocyte stimulating hormone (MSH), E92, E131, D154, D158, D178, and D332 are important for ligand binding. D121 and D332 are important for binding and signaling. Further experiments using other ligands such as D-Trp(8)-gamma-MSH, alpha-MSH and gamma-MSH showed that different ligands induce or select different conformations. In summary, we showed that acidic residues in TMs 1 and 3 are important for ligand binding whereas the acidic residues in TMs 2 and 7 are important for both ligand binding and signaling.
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Affiliation(s)
- Shu-Xiu Wang
- Department of Anatomy, Physiology and Pharmacology, 213 Greene Hall, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA
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