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Melanocortin-5 Receptor: Pharmacology and Its Regulation of Energy Metabolism. Int J Mol Sci 2022; 23:ijms23158727. [PMID: 35955857 PMCID: PMC9369360 DOI: 10.3390/ijms23158727] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Revised: 07/29/2022] [Accepted: 08/03/2022] [Indexed: 12/12/2022] Open
Abstract
As the most recent melanocortin receptor (MCR) identified, melanocortin-5 receptor (MC5R) has unique tissue expression patterns, pharmacological properties, and physiological functions. Different from the other four MCR subtypes, MC5R is widely distributed in both the central nervous system and peripheral tissues and is associated with multiple functions. MC5R in sebaceous and preputial glands regulates lipid production and sexual behavior, respectively. MC5R expressed in immune cells is involved in immunomodulation. Among the five MCRs, MC5R is the predominant subtype expressed in skeletal muscle and white adipose tissue, tissues critical for energy metabolism. Activated MC5R triggers lipid mobilization in adipocytes and glucose uptake in skeletal muscle. Therefore, MC5R is a potential target for treating patients with obesity and diabetes mellitus. Melanocortin-2 receptor accessory proteins can modulate the cell surface expression, dimerization, and pharmacology of MC5R. This minireview summarizes the molecular and pharmacological properties of MC5R and highlights the progress made on MC5R in energy metabolism. We poInt. out knowledge gaps that need to be explored in the future.
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Arakawa H, Higuchi Y. Exocrine scent marking: Coordinative role of arginine vasopressin in the systemic regulation of social signaling behaviors. Neurosci Biobehav Rev 2022; 136:104597. [PMID: 35248677 DOI: 10.1016/j.neubiorev.2022.104597] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 03/01/2022] [Accepted: 03/01/2022] [Indexed: 12/25/2022]
Abstract
Arginine vasopressin (AVP) is a neurohypophysial hormone that coordinatively regulates central socio-emotional behavior and peripheral control of antidiuretic fluid homeostasis. Most mammals, including rodents, utilize exocrine or urine-contained scent marking as a social signaling tool that facilitates social adaptation. The exocrine scent marking behavior is postulated to fine-tune sensory and cognitive abilities to recognize key social features via exocrine/urinary olfactory cues and subsequently control exocrine deposition or urinary marking through the mediation of osmotic fluid balance. AVP is implicated as a major player in controlling both recognition and signaling responses. This review provides constructive hypotheses on the coordinative processes of the AVP neurohypophysial circuits in the systemic regulations of fluid control and social-communicative behavior, via the expression of exocrine scent marking, and further emphasizes a potential role of AVP in a common mechanism underlying social communication in rodents.
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Affiliation(s)
- Hiroyuki Arakawa
- Depertment of Systems Physiology, University of the Ryukyus School of Medicine, Okinawa, Japan.
| | - Yuki Higuchi
- Depertment of Systems Physiology, University of the Ryukyus School of Medicine, Okinawa, Japan
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Liu T, Yi TL, Yang DQ, Tao YX. Regulation of melanocortin-5 receptor pharmacology by two isoforms of MRAP2 in ricefield eel (Monopterus albus). Gen Comp Endocrinol 2021; 314:113928. [PMID: 34653433 DOI: 10.1016/j.ygcen.2021.113928] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 10/06/2021] [Accepted: 10/09/2021] [Indexed: 11/18/2022]
Abstract
The melanocortin-5 receptor (MC5R) has been implicated in the regulation of exocrine gland secretion, immune regulation, and muscle fatty acid oxidation in mammals. Melanocortin-2 receptor accessory protein 2 (MRAP2) can modulate trafficking, ligand binding, and signaling of melanocortin receptors. To explore potential interaction between ricefield eel (Monopterus albus) MC5R and MRAP2s (maMC5R, maMRAP2X1, and maMRAP2X2), herein we studied the pharmacological characteristics of maMC5R and its modulation by maMRAP2s expressed in the human embryonic kidney cells. Three agonists, α-melanocyte-stimulating hormone (α-MSH), ACTH (1-24), and [Nle4, D-Phe7]-α-MSH, could bind to maMC5R and induce intracellular cAMP production dose-dependently. Compared with human MC5R (hMC5R), maMC5R displayed decreased maximal binding but higher binding affinity to α-MSH or ACTH (1-24). When stimulated with α-MSH or ACTH (1-24), maMC5R showed significantly lower EC50 and maximal response than hMC5R. Two maMRAP2s had no effect on cell surface expression of maMC5R, whereas they significantly increased maximal binding. Only maMRAP2X2 significantly decreased the binding affinity of ACTH (1-24). Both maMRAP2X1 and maMRAP2X2 significantly reduced maMC5R efficacy but did not affect ligand sensitivity. The availability of maMC5R pharmacological characteristics and modulation by maMRAP2s will assist the investigation of its roles in regulating diverse physiological processes in ricefield eel.
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Affiliation(s)
- Ting Liu
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States
| | - Ti-Lin Yi
- School of Animal Science, Yangtze University, Jingzhou 434020, Hubei, China
| | - Dai-Qin Yang
- School of Animal Science, Yangtze University, Jingzhou 434020, Hubei, China
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States.
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Differential Regulation of Gonadotropins as Revealed by Transcriptomes of Distinct LH and FSH Cells of Fish Pituitary. Int J Mol Sci 2021; 22:ijms22126478. [PMID: 34204216 PMCID: PMC8234412 DOI: 10.3390/ijms22126478] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 06/02/2021] [Accepted: 06/10/2021] [Indexed: 02/08/2023] Open
Abstract
From mammals to fish, reproduction is driven by luteinizing hormone (LH) and follicle-stimulating hormone (FSH) temporally secreted from the pituitary gland. Teleost fish are an excellent model for addressing the unique regulation and function of each gonadotropin cell since, unlike mammals, they synthesize and secrete LH and FSH from distinct cells. Only very distant vertebrate classes (such as fish and birds) demonstrate the mono-hormonal strategy, suggesting a potential convergent evolution. Cell-specific transcriptome analysis of double-labeled transgenic tilapia expressing GFP and RFP in LH or FSH cells, respectively, yielded genes specifically enriched in each cell type, revealing differences in hormone regulation, receptor expression, cell signaling, and electrical properties. Each cell type expresses a unique GPCR signature that reveals the direct regulation of metabolic and homeostatic hormones. Comparing these novel transcriptomes to that of rat gonadotrophs revealed conserved genes that might specifically contribute to each gonadotropin activity in mammals, suggesting conserved mechanisms controlling the differential regulation of gonadotropins in vertebrates.
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Xu Y, Guan X, Zhou R, Gong R. Melanocortin 5 receptor signaling pathway in health and disease. Cell Mol Life Sci 2020; 77:3831-3840. [PMID: 32248247 DOI: 10.1007/s00018-020-03511-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 03/17/2020] [Accepted: 03/24/2020] [Indexed: 12/20/2022]
Abstract
Melanocortin hormone system plays a key role in maintaining the homeostasis of our body via their neuro-immune-endocrine activities and regulates a diverse array of physiological functions, including melanogenesis, inflammation, immunomodulation, adrenocortical steroidogenesis, hemodynamics, natriuresis, energy homeostasis, sexual function, and exocrine secretion. The pathobiologic actions of all melanocortins are conveyed by melanocortin receptors. As the last melanocortin receptor to be cloned and characterized, melanocortin receptor 5 (MC5R) is widely expressed in both central nervous system and a number of peripheral organ systems in man. However, the exact effect of the MC5R mediated melanocortinergic signaling remains largely uncertain. Owing to the recent advances in developing highly selective peptidomimetic agonists and antagonists of MC5R and also to studies in MC5R knockout animals, our understanding of MC5R pathobiology has been greatly expanded and strengthened. Evidence suggests that MC5R plays a key role in governing immune reaction and inflammatory response, and is pivotal for the regulation of sexual behavior, thermoregulation, and exocrine secretion, like sebogenesis, lacrimal secretion and release of sex pheromones. As such, recent translational efforts have focused on developing novel sebum-suppressive therapies for seborrhoea and acne vulgaris based on antagonizing MC5R. Conversely, selective MC5R agonists have demonstrated promising beneficial effects in immune-mediated diseases, metabolic endocrinopathies and other disease conditions, such as glomerular diseases and dry eyes, skin and mouth. Thus, MC5R-mediated signaling is essential for health. Therapeutic targeting of MC5R represents a promising and pragmatic therapeutic strategy for diverse diseases. This review article delineates the biophysiology of MC5R-mediated biophysiology of the melanocortin hormone system, discusses the existing data on MC5R-targeted therapy in experimental disease models, and envisages the translational potential for treating human diseases.
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Affiliation(s)
- Yahong Xu
- Division of Kidney Disease and Hypertension, Department of Medicine, Brown University School of Medicine, Providence, RI, USA.,Department of Nephrology, Yangpu Hospital, Tongji University School of Medicine, Shanghai, China
| | - Xuejing Guan
- Division of Nephrology, Department of Medicine, The University of Toledo College of Medicine, Toledo, OH, USA
| | - Rong Zhou
- Department of Nephrology, Yangpu Hospital, Tongji University School of Medicine, Shanghai, China
| | - Rujun Gong
- Division of Kidney Disease and Hypertension, Department of Medicine, Brown University School of Medicine, Providence, RI, USA. .,Division of Nephrology, Department of Medicine, The University of Toledo College of Medicine, Toledo, OH, USA.
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Seddon RJ, Hews DK. Melanization, α-melanocyte stimulating hormone and steroid hormones in male western fence lizards from nine populations. Gen Comp Endocrinol 2020; 285:113287. [PMID: 31563645 DOI: 10.1016/j.ygcen.2019.113287] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 08/29/2019] [Accepted: 09/22/2019] [Indexed: 02/05/2023]
Abstract
Hormones can mediate suites of correlated traits. Melanocortins regulate melanin synthesis and elements of the melanocortin system can directly, and indirectly, affect a number of other traits, such as stress reactivity. Trait correlations within the melanocortin system have been studied mainly in birds and mammals but less so in reptiles. We examined adult male western fence lizards (Sceloporus occidentalis) and if melanization was correlated with plasma levels of three hormones, including peptide hormone α-melanocyte stimulating hormone (α-MSH), testosterone and corticosterone, and ectoparasite loads. This lizard is darker at higher elevations in California, and we compared five high-elevation and four low-elevation populations during comparable periods of the breeding season at each site. We first validated use of an α-MSH assay kit with lizard plasma. Since Anolis carolinensis is one of the few species with published values for α-MSH plasma levels, we assayed both Anolis and Sceloporus plasma and compared hormone values to those we generated for Anolis to the publish values. We also evaluated effects of different methods of storing spiked plasma pools on resulting α-MSH concentrations. Plasma levels of α-MSH did not differ significantly, but some populations differed significantly in mean corticosterone and mean testosterone. Combining all individuals from the nine populations, we found that individual variation in α-MSH was not associated with individual variation in melanization, but levels of α-MSH were positively associated with plasma testosterone and negatively associated with corticosterone. The lack of association between individual levels of melanization and expression of most other traits differs from a growing number of within-population studies of melanization, and we discuss what differences in physiological mechanisms could produce different hypothetical patterns. Circulating levels of -MSH are only one element of the melanocortin system; in situ synthesis of α-MSH by the skin and the diversity of melanocortin receptors could also contribute to variation in traits mediated by the melanocortin system and should be examined.
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Affiliation(s)
- Ryan J Seddon
- Department of Biology, Indiana State University, Terre Haute, IN 47809, USA.
| | - Diana K Hews
- Department of Biology, Indiana State University, Terre Haute, IN 47809, USA.
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Vestlund J, Winsa-Jörnulf J, Hovey D, Lundström S, Lichtenstein P, Anckarsäter H, Studer E, Suchankova P, Westberg L, Jerlhag E. Ghrelin and aggressive behaviours-Evidence from preclinical and human genetic studies. Psychoneuroendocrinology 2019; 104:80-88. [PMID: 30818255 DOI: 10.1016/j.psyneuen.2019.02.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 02/18/2019] [Accepted: 02/19/2019] [Indexed: 01/06/2023]
Abstract
Aggressive behaviour is of crucial importance in the defence for limited resources including food and mates and involves central serotonin as well as dopamine signalling. As ghrelin modulates food intake and sexual behaviour we initially investigated the hypothesis that central ghrelin signalling regulates aggressive behaviour in the resident intruder paradigm in male mice. Moreover, interaction between ghrelin signalling and serotonergic, noradrenergic as well as dopaminergic neurotransmission in aggression was investigated. The relevance of ghrelin for human aggression per se as well as for aggression induced by alcohol was evaluated in a human genetic association study comprising young men (n = 784) from the normal population assessed for anti-social behaviours. The present study demonstrates that central ghrelin infusion, but not ghrelin administered systemically, increases aggression. Moreover aggressive behaviour is decreased by pharmacological suppression of the growth hormone secretagogue receptor-1 A (GHSR-1A) by JMV2959. As indicated by the ex vivo biochemical data serotonin, rather than dopamine or noradrenaline, in amygdala may have central roles for the ability of JMV2959 to reduce aggression. This link between central serotonin, GHSR-1A and aggression is further substantiated by the behavioural data showing that JMV2959 cannot decrease aggression following depletion of central serotonin signalling. The genetic association study demonstrates that males carrying the Leu72Leu genotype of the pre-pro-ghrelin gene and displaying hazardous alcohol use are more aggressive when compared to the group carrying the Met-allele. Collectively, this contributes to the identification of central ghrelin pathway as an important modulator in the onset of aggressive behaviours in male mice.
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Affiliation(s)
- Jesper Vestlund
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Julia Winsa-Jörnulf
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Daniel Hovey
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Sebastian Lundström
- Institute of Neuroscience and Physiology, Gillberg Neuropsychiatry Centre, University of Gothenburg, Sweden
| | - Paul Lichtenstein
- Karolinska Institutet, Department of Medical Epidemiology and Biostatistics, Stockholm, Sweden
| | - Henrik Anckarsäter
- Institute of Neuroscience and Physiology, Centre of Ethics, Law and Mental Health (CELAM), University of Gothenburg, Sweden
| | - Erik Studer
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Petra Suchankova
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Lars Westberg
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Elisabet Jerlhag
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
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Culumber ZW, Kraft B, Lemakos V, Hoffner E, Travis J, Hughes KA. GxG epistasis in growth and condition and the maintenance of genetic polymorphism in
Gambusia holbrooki. Evolution 2018; 72:1146-1154. [DOI: 10.1111/evo.13474] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 02/28/2018] [Accepted: 02/28/2018] [Indexed: 11/29/2022]
Affiliation(s)
- Zachary W. Culumber
- Department of Biological Science Florida State University 319 Stadium Drive Tallahassee FL 32306
| | - Brittany Kraft
- Department of Biological Science Florida State University 319 Stadium Drive Tallahassee FL 32306
| | - Valerie Lemakos
- Department of Biological Science Florida State University 319 Stadium Drive Tallahassee FL 32306
| | - Erika Hoffner
- Department of Biological Science Florida State University 319 Stadium Drive Tallahassee FL 32306
| | - Joseph Travis
- Department of Biological Science Florida State University 319 Stadium Drive Tallahassee FL 32306
| | - Kimberly A. Hughes
- Department of Biological Science Florida State University 319 Stadium Drive Tallahassee FL 32306
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Novoselova TV, Chan LF, Clark AJL. Pathophysiology of melanocortin receptors and their accessory proteins. Best Pract Res Clin Endocrinol Metab 2018; 32:93-106. [PMID: 29678289 DOI: 10.1016/j.beem.2018.02.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The melanocortin receptors (MCRs) and their accessory proteins (MRAPs) are involved in regulation of a diverse range of endocrine pathways. Genetic variants of these components result in phenotypic variation and disease. The MC1R is expressed in skin and variants in the MC1R gene are associated with ginger hair color. The MC2R mediates the action of ACTH in the adrenal gland to stimulate glucocorticoid production and MC2R mutations result in familial glucocorticoid deficiency (FGD). MC3R and MC4R are involved in metabolic regulation and their gene variants are associated with severe pediatric obesity, whereas the function of MC5R remains to be fully elucidated. MRAPs have been shown to modulate the function of MCRs and genetic variants in MRAPs are associated with diseases including FGD type 2 and potentially early onset obesity. This review provides an insight into recent advances in MCRs and MRAPs physiology, focusing on the disorders associated with their dysfunction.
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Affiliation(s)
- T V Novoselova
- Centre for Endocrinology, William Harvey Research Institute, Queen Mary University of London, Chartehouse Square, London, EC1M 6BQ, United Kingdom.
| | - L F Chan
- Centre for Endocrinology, William Harvey Research Institute, Queen Mary University of London, Chartehouse Square, London, EC1M 6BQ, United Kingdom
| | - A J L Clark
- Centre for Endocrinology, William Harvey Research Institute, Queen Mary University of London, Chartehouse Square, London, EC1M 6BQ, United Kingdom
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Gonçalves JPL, Palmer D, Meldal M. MC4R Agonists: Structural Overview on Antiobesity Therapeutics. Trends Pharmacol Sci 2018; 39:402-423. [PMID: 29478721 DOI: 10.1016/j.tips.2018.01.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 01/28/2018] [Accepted: 01/30/2018] [Indexed: 01/08/2023]
Abstract
The melanocortin-4 receptor (MC4R) regulates adipose tissue formation and energy homeostasis, and is believed to be a monogenic target for novel antiobesity therapeutics. Several research efforts targeting this receptor have identified potent and selective agonists. While viable agonists have been characterized in vitro, undesirable side effects frequently appeared during clinical trials. The most promising candidates have diverse structures, including linear peptides, cyclic peptides, and small molecules. Herein, we present a compilation of potent MC4R agonists and discuss the pivotal structural differences within those molecules that resulted in good selectivity for MC4R over other melanocortins. We provide insight on recent progress in the field and reflect on directions for development of new agonists.
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Affiliation(s)
- Juliana Pereira Lopes Gonçalves
- Center for Evolutionary Chemical Biology, Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark.
| | - Daniel Palmer
- Center for Evolutionary Chemical Biology, Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Morten Meldal
- Center for Evolutionary Chemical Biology, Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark.
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Bohls P, Koehnle TJ. Responses of Eastern Gray Squirrels (Sciurus carolinensis) to Predator Calls and Their Modulation by Coat Color. AMERICAN MIDLAND NATURALIST 2017. [DOI: 10.1674/0003-0031-178.2.226] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Patricia Bohls
- Department of Entomology and Nematology, 1 Shields Avenue, University of California, Davis 95616
| | - Thomas J. Koehnle
- Neuroscience Program, Department of Biology, 11715 Garfield Rd, Hiram College, Hiram, Ohio 44234
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12
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Enriori PJ, Chen W, Garcia-Rudaz MC, Grayson BE, Evans AE, Comstock SM, Gebhardt U, Müller HL, Reinehr T, Henry BA, Brown RD, Bruce CR, Simonds SE, Litwak SA, McGee SL, Luquet S, Martinez S, Jastroch M, Tschöp MH, Watt MJ, Clarke IJ, Roth CL, Grove KL, Cowley MA. α-Melanocyte stimulating hormone promotes muscle glucose uptake via melanocortin 5 receptors. Mol Metab 2016; 5:807-822. [PMID: 27688995 PMCID: PMC5034615 DOI: 10.1016/j.molmet.2016.07.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2016] [Revised: 07/26/2016] [Accepted: 07/28/2016] [Indexed: 01/21/2023] Open
Abstract
Objective Central melanocortin pathways are well-established regulators of energy balance. However, scant data exist about the role of systemic melanocortin peptides. We set out to determine if peripheral α-melanocyte stimulating hormone (α-MSH) plays a role in glucose homeostasis and tested the hypothesis that the pituitary is able to sense a physiological increase in circulating glucose and responds by secreting α-MSH. Methods We established glucose-stimulated α-MSH secretion using humans, non-human primates, and mouse models. Continuous α-MSH infusions were performed during glucose tolerance tests and hyperinsulinemic-euglycemic clamps to evaluate the systemic effect of α-MSH in glucose regulation. Complementary ex vivo and in vitro techniques were employed to delineate the direct action of α-MSH via the melanocortin 5 receptor (MC5R)–PKA axis in skeletal muscles. Combined treatment of non-selective/selective phosphodiesterase inhibitor and α-MSH was adopted to restore glucose tolerance in obese mice. Results Here we demonstrate that pituitary secretion of α-MSH is increased by glucose. Peripheral α-MSH increases temperature in skeletal muscles, acts directly on soleus and gastrocnemius muscles to significantly increase glucose uptake, and enhances whole-body glucose clearance via the activation of muscle MC5R and protein kinase A. These actions are absent in obese mice, accompanied by a blunting of α-MSH-induced cAMP levels in skeletal muscles of obese mice. Both selective and non-selective phosphodiesterase inhibition restores α-MSH induced skeletal muscle glucose uptake and improves glucose disposal in obese mice. Conclusion These data describe a novel endocrine circuit that modulates glucose homeostasis by pituitary α-MSH, which increases muscle glucose uptake and thermogenesis through the activation of a MC5R-PKA-pathway, which is disrupted in obesity. Glucose stimulates α-MSH release from the pituitary. Systemic α-MSH drives glucose disposal and thermogenesis in skeletal muscles. α-MSH acts on MC5R expressed on skeletal muscles and activate cAMP-PKA pathway. The combined treatment of nonselective or selective PDE 4 inhibitor and α-MSH ameliorates glucose intolerance in obese mice.
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Affiliation(s)
- Pablo J Enriori
- Biomedical Discovery Institute/Department of Physiology, Monash University, Vic, Australia
| | - Weiyi Chen
- Biomedical Discovery Institute/Department of Physiology, Monash University, Vic, Australia
| | - Maria C Garcia-Rudaz
- Biomedical Discovery Institute/Department of Physiology, Monash University, Vic, Australia
| | | | - Anne E Evans
- Division Neuroscience, Oregon Health and Science University, Oregon, USA
| | - Sarah M Comstock
- Division Neuroscience, Oregon Health and Science University, Oregon, USA
| | - Ursel Gebhardt
- Department of Pediatrics, Vestische Children Hospital Datteln, University of Witten/Herdecke, Germany
| | - Hermann L Müller
- Department of Pediatrics, Vestische Children Hospital Datteln, University of Witten/Herdecke, Germany
| | - Thomas Reinehr
- Department of Pediatrics, Klinikum Oldenburg GmbH, Germany
| | - Belinda A Henry
- Biomedical Discovery Institute/Department of Physiology, Monash University, Vic, Australia
| | - Russell D Brown
- Biomedical Discovery Institute/Department of Physiology, Monash University, Vic, Australia
| | - Clinton R Bruce
- Biomedical Discovery Institute/Department of Physiology, Monash University, Vic, Australia
| | - Stephanie E Simonds
- Biomedical Discovery Institute/Department of Physiology, Monash University, Vic, Australia
| | - Sara A Litwak
- Biomedical Discovery Institute/Department of Physiology, Monash University, Vic, Australia
| | - Sean L McGee
- Metabolic Research Unit, School of Medicine, Deakin University, Vic, Australia
| | - Serge Luquet
- Univ Paris Diderot, Sorbonne Paris Cité, Unité de Biologie Fonctionnelle et Adaptative, CNRS UMR 8251, F-75205 Paris, France
| | - Sarah Martinez
- Univ Paris Diderot, Sorbonne Paris Cité, Unité de Biologie Fonctionnelle et Adaptative, CNRS UMR 8251, F-75205 Paris, France
| | - Martin Jastroch
- Institute for Diabetes and Obesity, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg & Division of Metabolic Diseases, Technische Universität, München, Germany
| | - Matthias H Tschöp
- Institute for Diabetes and Obesity, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg & Division of Metabolic Diseases, Technische Universität, München, Germany
| | - Matthew J Watt
- Biomedical Discovery Institute/Department of Physiology, Monash University, Vic, Australia
| | - Iain J Clarke
- Biomedical Discovery Institute/Department of Physiology, Monash University, Vic, Australia
| | - Christian L Roth
- Division of Endocrinology, Seattle Children's Hospital Research Institute, WA, USA
| | - Kevin L Grove
- Division Neuroscience, Oregon Health and Science University, Oregon, USA
| | - Michael A Cowley
- Biomedical Discovery Institute/Department of Physiology, Monash University, Vic, Australia.
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Anderson EJP, Çakir I, Carrington SJ, Cone RD, Ghamari-Langroudi M, Gillyard T, Gimenez LE, Litt MJ. 60 YEARS OF POMC: Regulation of feeding and energy homeostasis by α-MSH. J Mol Endocrinol 2016; 56:T157-74. [PMID: 26939593 PMCID: PMC5027135 DOI: 10.1530/jme-16-0014] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 03/01/2016] [Indexed: 12/20/2022]
Abstract
The melanocortin peptides derived from pro-opiomelanocortin (POMC) were originally understood in terms of the biological actions of α-melanocyte-stimulating hormone (α-MSH) on pigmentation and adrenocorticotrophic hormone on adrenocortical glucocorticoid production. However, the discovery of POMC mRNA and melanocortin peptides in the CNS generated activities directed at understanding the direct biological actions of melanocortins in the brain. Ultimately, discovery of unique melanocortin receptors expressed in the CNS, the melanocortin-3 (MC3R) and melanocortin-4 (MC4R) receptors, led to the development of pharmacological tools and genetic models leading to the demonstration that the central melanocortin system plays a critical role in the regulation of energy homeostasis. Indeed, mutations in MC4R are now known to be the most common cause of early onset syndromic obesity, accounting for 2-5% of all cases. This review discusses the history of these discoveries, as well as the latest work attempting to understand the molecular and cellular basis of regulation of feeding and energy homeostasis by the predominant melanocortin peptide in the CNS, α-MSH.
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Affiliation(s)
- Erica J P Anderson
- Department of Molecular Physiology and BiophysicsVanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Isin Çakir
- Department of Molecular Physiology and BiophysicsVanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Sheridan J Carrington
- Department of Molecular Physiology and BiophysicsVanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Roger D Cone
- Department of Molecular Physiology and BiophysicsVanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Masoud Ghamari-Langroudi
- Department of Molecular Physiology and BiophysicsVanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Taneisha Gillyard
- Department of Molecular Physiology and BiophysicsVanderbilt University School of Medicine, Nashville, Tennessee, USA Meharry Medical CollegeDepartment of Neuroscience and Pharmacology, Nashville, Tennessee, USA
| | - Luis E Gimenez
- Department of Molecular Physiology and BiophysicsVanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Michael J Litt
- Department of Molecular Physiology and BiophysicsVanderbilt University School of Medicine, Nashville, Tennessee, USA
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14
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Carola V, Perlas E, Zonfrillo F, Soini HA, Novotny MV, Gross CT. Modulation of social behavior by the agouti pigmentation gene. Front Behav Neurosci 2014; 8:259. [PMID: 25136298 PMCID: PMC4117936 DOI: 10.3389/fnbeh.2014.00259] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 07/13/2014] [Indexed: 11/13/2022] Open
Abstract
Agouti is a secreted neuropeptide that acts as an endogenous antagonist of melanocortin receptors. Mice and rats lacking agouti (called non-agouti) have dark fur due to a disinhibition of melanocortin signaling and pigment deposition in the hair follicle. Non-agouti animals have also been reported to exhibit altered behavior, despite no evidence for the expression of agouti outside the skin. Here we confirm that non-agouti mice show altered social behavior and uncover expression of agouti in the preputial gland, a sebaceous organ in the urinary tract that secretes molecules involved in social behavior. Non-agouti mice had enlarged preputial glands and altered levels of putative preputial pheromones and surgical removal of the gland reversed the behavioral phenotype. These findings demonstrate the existence of an autologous, out-of-skin pathway for the modulation of social behavior.
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Affiliation(s)
- Valeria Carola
- IRCCS Fondazione Santa Lucia Rome, Italy ; Mouse Biology Unit, European Molecular Biology Laboratory Monterotondo, Italy
| | - Emerald Perlas
- Mouse Biology Unit, European Molecular Biology Laboratory Monterotondo, Italy
| | - Francesca Zonfrillo
- Mouse Biology Unit, European Molecular Biology Laboratory Monterotondo, Italy
| | - Helena A Soini
- Department of Chemistry, Institute for Pheromone Research, Indiana University Bloomington, IN, USA
| | - Milos V Novotny
- Department of Chemistry, Institute for Pheromone Research, Indiana University Bloomington, IN, USA
| | - Cornelius T Gross
- Mouse Biology Unit, European Molecular Biology Laboratory Monterotondo, Italy
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15
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Fargallo JA, Velando A, Lopez-Rull I, Ganan N, Lifshitz N, Wakamatsu K, Torres R. Sex-specific phenotypic integration: endocrine profiles, coloration, and behavior in fledgling boobies. Behav Ecol 2013. [DOI: 10.1093/beheco/art088] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
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16
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Novoselova TV, Jackson D, Campbell DC, Clark AJL, Chan LF. Melanocortin receptor accessory proteins in adrenal gland physiology and beyond. J Endocrinol 2013; 217:R1-11. [PMID: 23418361 DOI: 10.1530/joe-12-0501] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The melanocortin receptor (MCR) family consists of five G-protein-coupled receptors (MC1R-MC5R) with diverse physiological roles. MC1R controls pigmentation, MC2R is a critical component of the hypothalamic-pituitary-adrenal axis, MC3R and MC4R have a vital role in energy homeostasis and MC5R is involved in exocrine function. The melanocortin receptor accessory protein (MRAP) and its paralogue MRAP2 are small single-pass transmembrane proteins that have been shown to regulate MCR expression and function. In the adrenal gland, MRAP is an essential accessory factor for the functional expression of the MC2R/ACTH receptor. The importance of MRAP in adrenal gland physiology is demonstrated by the clinical condition familial glucocorticoid deficiency, where inactivating MRAP mutations account for ∼20% of cases. MRAP is highly expressed in both the zona fasciculata and the undifferentiated zone. Expression in the undifferentiated zone suggests that MRAP could also be important in adrenal cell differentiation and/or maintenance. In contrast, the role of adrenal MRAP2, which is highly expressed in the foetal gland, is unclear. The expression of MRAPs outside the adrenal gland is suggestive of a wider physiological purpose, beyond MC2R-mediated adrenal steroidogenesis. In vitro, MRAPs have been shown to reduce surface expression and signalling of all the other MCRs (MC1,3,4,5R). MRAP2 is predominantly expressed in the hypothalamus, a site that also expresses a high level of MC3R and MC4R. This raises the intriguing possibility of a CNS role for the MRAPs.
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Affiliation(s)
- T V Novoselova
- Centre for Endocrinology, Queen Mary University of London, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Charterhouse Square, London EC1M6BQ, UK
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17
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Ramachandrappa S, Gorrigan RJ, Clark AJL, Chan LF. The melanocortin receptors and their accessory proteins. Front Endocrinol (Lausanne) 2013; 4:9. [PMID: 23404466 PMCID: PMC3567503 DOI: 10.3389/fendo.2013.00009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Accepted: 01/25/2013] [Indexed: 12/26/2022] Open
Abstract
The five melanocortin receptors (MCRs) named MC1R-MC5R have diverse physiological roles encompassing pigmentation, steroidogenesis, energy homeostasis and feeding behavior as well as exocrine function. Since their identification almost 20 years ago much has been learnt about these receptors. As well as interacting with their endogenous ligands the melanocortin peptides, there is now a growing list of important peptides that can modulate the way these receptors signal, acting as agonists, antagonists, and inverse agonists. The discovery of melanocortin 2 receptor accessory proteins as a novel accessory factor to the MCRs provides further insight into the regulation of these important G protein-coupled receptor.
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Affiliation(s)
| | | | | | - Li F. Chan
- *Correspondence: Li F. Chan, Centre for Endocrinology, William Harvey Research Institute, Queen Mary University of London, Barts and The London School of Medicine and Dentistry, Charterhouse Square, London EC1M 6BQ, UK. e-mail:
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18
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Sukseree S, Rossiter H, Mildner M, Pammer J, Buchberger M, Gruber F, Watanapokasin R, Tschachler E, Eckhart L. Targeted deletion of Atg5 reveals differential roles of autophagy in keratin K5-expressing epithelia. Biochem Biophys Res Commun 2013; 430:689-94. [DOI: 10.1016/j.bbrc.2012.11.090] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2012] [Accepted: 11/21/2012] [Indexed: 11/25/2022]
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19
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Morgan C. Plasticity in photoperiodic regulation of adrenal, but not testicular, function in Syrian hamsters. Gen Comp Endocrinol 2012; 178:441-9. [PMID: 22771551 DOI: 10.1016/j.ygcen.2012.06.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 06/16/2012] [Accepted: 06/20/2012] [Indexed: 01/25/2023]
Abstract
Transfer from long days (LD) to short days (SD) increases aggressive behavior, but it suppresses the hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-gonadal (HPG) axes in male Syrian hamsters. The present study sought to determine whether social instability (group housing from days 1-70, single housing from days 71 to 84, and 10-min social encounters during the light or dark phase on days 82 and 83) could reverse SD-induced quiescence in the aggression-promoting HPA and HPG axes. Controls were housed in stable groups during LD or SD exposure. Euthanasia occurred on day 84 during the light or dark phase (unstable condition) and during the dark phase (stable condition). SD exposure in the unstable condition increased aggression during social pairings, and it elevated circulating corticosterone, cortisol, and adrenocorticotropic hormone (ACTH) concentrations, assessed by RIA, particularly during the dark phase. Although anterior pituitary pro-opiomelanocortin (POMC) immunoreactivity was unaltered by these experimental conditions, SD and the dark phase during social instability elevated POMC mRNA levels, assessed by solution hybridization assay. In socially stable controls, SD exposure increased aggression, assessed by bite marks, reduced cortisol and ACTH, but not corticosterone, secretion, and it reduced anterior pituitary POMC mRNA, but not immunoreactivity, levels. SD exposure in both conditions reduced testicular function, indicated by more than 77% reduction of testis mass. These results suggest that social instability, rather than aggression per se, reversed SD-induced suppression of HPA, but not HPG, function.
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Affiliation(s)
- Caurnel Morgan
- Department of Nutrition & Food Science, Texas A&M University, College Station, TX 77843, USA.
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20
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Pale and dark reddish melanic tawny owls differentially regulate the level of blood circulating POMC prohormone in relation to environmental conditions. Oecologia 2011; 166:913-21. [DOI: 10.1007/s00442-011-1955-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Accepted: 02/21/2011] [Indexed: 10/18/2022]
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21
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Sánchez E, Rubio VC, Cerdá-Reverter JM. Characterization of the sea bass melanocortin 5 receptor: a putative role in hepatic lipid metabolism. ACTA ACUST UNITED AC 2010; 212:3901-10. [PMID: 19915133 DOI: 10.1242/jeb.035121] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The melanocortin 5 receptor (MC5R) plays a key role in the regulation of exocrine secretion in mammalian species. This receptor has also been characterized in some fish species but its function is unknown. We report the molecular and pharmacological characterization, as well as the tissue expression pattern, of sea bass MC5R. Cloning of five active alleles showing different levels of sensitivity to endogenous melanocortin and one non-functional allele demonstrate the allelic complexity of the MC5R locus. The sea bass receptor was activated by all the melanocortins tested, with ACTH and desacetyl-MSH and beta-MSH showing the lowest efficiency. The acetylation of the MSH isoforms seems to be critical for the effectiveness of the agonist. Agouti-related protein had no effect on basal or agonist-stimulated activation of the receptor. SbMC5R was mainly expressed in the brain but lower expression levels were found in several peripheral tissues, including liver. Progressive fasting did not induce up- or downregulation of hypothalamic MC5R expression, suggesting that central MC5R is not involved in the regulation of food intake in the sea bass. MTII, a sbMC5R agonist, stimulated hepatic lipolysis in vitro, measured as free fatty acid release into the culture medium after melanocortin agonist exposure of liver fragments, suggesting that MC5R is involved in the regulation of hepatic lipid metabolism. Taken together, the data suggest that different allelic combinations may confer differential sensitivity to endogenous melanocortin in tissues where MC5R is expressed and, by extension, in hepatic lipid metabolism.
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Affiliation(s)
- E Sánchez
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, 12595 Torre de la Sal, Ribera de Cabanes, Castellón, Spain
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22
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Williams D, Devi LA. Escorts take the lead molecular chaperones as therapeutic targets. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2010; 91:121-49. [PMID: 20691961 DOI: 10.1016/s1877-1173(10)91005-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The functional and physiological diversity of transmembrane receptors results from factors that influence the pharmacology, signaling, and trafficking of these receptors. Receptor mutations and other modifications may lead to misfolding, intracellular retention, and ineffective signaling of transmembrane receptors. The importance of such mutations is highlighted by the fact that various diseases have been linked to mutations that lead to ineffective signaling of these receptors, resulting from the retention of receptors in intracellular compartments. Studies focused on understanding the regulation of trafficking and cell surface expression of newly synthesized receptors have highlighted molecular chaperones as key regulators of receptor maturation and sorting. In this chapter, we discuss the functions of molecular chaperones in the regulation of seven-transmembrane-containing G-protein-coupled receptor function and trafficking and explore ways in which chaperones can serve as novel therapeutic targets.
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Affiliation(s)
- Dumaine Williams
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, USA
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23
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Sebag JA, Hinkle PM. Opposite effects of the melanocortin-2 (MC2) receptor accessory protein MRAP on MC2 and MC5 receptor dimerization and trafficking. J Biol Chem 2009; 284:22641-8. [PMID: 19535343 DOI: 10.1074/jbc.m109.022400] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
MC2 (ACTH) receptors require MC2 receptor accessory protein (MRAP) to reach the cell surface. In this study, we show that MRAP has the opposite effect on the closely related MC5 receptor. In enzyme-linked immunosorbent assay and microscopy experiments, MC2 receptor was retained in the endoplasmic reticulum in the absence of MRAP and targeted to the plasma membrane with MRAP. MC5 receptor was at the plasma membrane in the absence of MRAP, but trapped intracellularly when expressed with MRAP. Using bimolecular fluorescence complementation, where one fragment of yellow fluorescent protein (YFP) was fused to receptors and another to MRAP, we showed that MC2 receptor-MRAP dimers were present at the plasma membrane, whereas MC5 receptor-MRAP dimers were intracellular. Both MC2 and MC5 receptors co-precipitated with MRAP. MRAP did not alter expression of beta2-adrenergic receptors or co-precipitate with them. To determine if MRAP affects formation of receptor oligomers, we co-expressed MC2 receptors fused to YFP fragments in the presence or absence of MRAP. YFP fluorescence, reporting MC2 receptor homodimers, was readily detectable with or without MRAP. In contrast, MC5 receptor homodimers were visible in the absence of MRAP, but little fluorescence was observed by microscopic analysis when MRAP was co-expressed. Co-precipitation of differentially tagged receptors confirmed that MRAP blocks MC5 receptor dimerization. The regions of MRAP required for its effects on MC2 and MC5 receptors differed. These results establish that MRAP forms stable complexes with two different melanocortin receptors, facilitating surface expression of MC2 receptor but disrupting dimerization and surface localization of MC5 receptor.
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Affiliation(s)
- Julien A Sebag
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York 14642, USA
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24
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Abstract
Electric fish produce weak electric fields to image their world in darkness and to communicate with potential mates and rivals. Eavesdropping by electroreceptive predators exerts selective pressure on electric fish to shift their signals into less-detectable high-frequency spectral ranges. Hypopomid electric fish evolved a signal-cloaking strategy that reduces their detectability by predators in the lab (and thus presumably their risk of predation in the field). These fish produce broad-frequency electric fields close to the body, but the heterogeneous local fields merge over space to cancel the low-frequency spectrum at a distance. Mature males dynamically regulate this cloaking mechanism to enhance or suppress low-frequency energy. The mechanism underlying electric-field cloaking involves electrogenic cells that produce two independent action potentials. In a unique twist, these cells orient sodium and potassium currents in the same direction, potentially boosting their capabilities for current generation. Exploration of such evolutionary inventions could aid the design of biogenerators to power implantable medical devices, an ambition that would benefit from the complete genome sequence of a gymnotiform fish.
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Affiliation(s)
- Philip K Stoddard
- Philip K. Stoddard is a professor, and Michael R. Markham is a research associate, in the Department of Biological Sciences at Florida International University in Miami. They study the evolution, neurobiology, and behavior of communication
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25
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Bednarek MA, MacNeil T, Tang R, Fong TM, Angeles Cabello M, Maroto M, Teran A. Potent and Selective Peptide Agonists of ?-Melanocyte Stimulating Hormone (?MSH) Action at Human Melanocortin Receptor 5; their Synthesis and Biological Evaluation in vitro. Chem Biol Drug Des 2007; 69:350-5. [PMID: 17539827 DOI: 10.1111/j.1747-0285.2007.00513.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Melanocortin receptors (MC1-5R) and their endogenous ligands (melanocyte-stimulating hormones and adrenocorticotropic hormone) are involved in many physiological processes in humans. Of those receptors, the actions of MC5R are the least understood despite its broad presence in the numerous peripheral tissues and brain. In this study, we describe synthesis and pharmacological properties in vitro (receptor-binding affinity and agonist activity) of several cyclic analogs of alphaMSH which are potent agonists at hMC5R (EC(50) below 1 nM) and of enhanced receptor subtype selectivity (more than 2000-fold versus hMC1b,3R and about 70- to 200-fold versus hMC4R). These compounds are analogs of Ac-Nle(4)-cyclo[Asp(5)-His(6)-D-Nal(2')(7)-Pip(8)-Trp(9)-Lys(10)]-NH(2) (Pip: pipecolic acid) in which His(6) has been replaced with sterically hindered amino acids. They may be useful tools in the elucidation of the MC5R role in skin disorders and in immunomodulatory and in anti-inflammatory actions of alphaMSH.
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Affiliation(s)
- Maria A Bednarek
- Department of Medicinal Chemistry, Merck Research Laboratories, Rahway, NJ, USA.
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26
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Bednarek MA, MacNeil T, Tang R, Fong TM, Cabello MA, Maroto M, Teran A. Potent and selective agonists of alpha-melanotropin (alphaMSH) action at human melanocortin receptor 5; linear analogs of alpha-melanotropin. Peptides 2007; 28:1020-8. [PMID: 17376561 DOI: 10.1016/j.peptides.2007.02.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2006] [Revised: 02/08/2007] [Accepted: 02/12/2007] [Indexed: 10/23/2022]
Abstract
Alpha-melanotropin, Ac-Ser(1)-Tyr-Ser-Met-Glu-His(6)-Phe(7)-Arg(8)-Trp(9)-Gly-Lys-Pro-Val(13)-NH(2)(1), is a non-selective endogenous agonist for the melanocortin receptor 5; the receptor present in various peripheral tissues and in the brain, cortex and cerebellum. Most of the synthetic analogs of alphaMSH, including a broadly used and more potent the NDP-alphaMSH peptide, Ac-Ser(1)-Tyr-Ser-Nle(4)-Glu-His(6)-D-Phe(7)-Arg(8)-Trp(9)-Gly-Lys-Pro-Val(13)-NH(2), are also not particularly selective for MC5R. To elucidate physiological functions of the melanocortin receptor 5 in rodents and humans, the receptor subtype selective research tools are needed. We report herein syntheses and pharmacological evaluation in vitro of several analogs of NDP-alphaMSH which are highly potent and specific agonists for the human MC5R. The new linear peptides, of structures and solubility properties similar to those of the endogenous ligand alphaMSH, are exemplified by compound 7, Ac-Ser(1)-Tyr-Ser-Met-Glu-Oic(6)-D-4,4'-Bip(7)-Pip(8)-Trp(9)-Gly-Lys-Pro-Val(13)-NH(2) (Oic: octahydroindole-2-COOH, 4,4'-Bip: 4,4'-biphenylalanine, Pip: pipecolic acid), shortly NODBP-alphaMSH, which has an IC(50)=0.74 nM (binding assay) and EC(50)=0.41 (cAMP production assay) at hMC5R nM and greater than 3500-fold selectivity with respect to the melanocortin receptors 1b, 3 and 4. A shorter peptide derived from NODBP-alphaMSH: Ac-Nle-Glu-Oic(6)-D-4,4'-Bip(7)-Pip(8)-Trp(9) -NH(2) (17) was measured to be an agonist only 10-fold less potent at hMC5R than the full length parent peptide. In the structure of this smaller analog, the Nle-Glu-Oic(6)-D-4,4'-Bip(7)-Pip(8) segment was found to be critical for high agonist potency, while the C-terminal Trp(9) residue was shown to be required for high hMC5R selectivity versus hMC1b,3,4R.
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Affiliation(s)
- Maria A Bednarek
- Department of Medicinal Chemistry, Merck Research Laboratories, R50G-140, PO Box 2000, Rahway, NJ 07065, USA.
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27
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Abstract
The melanocortin system refers to a set of hormonal, neuropeptidergic, and paracrine signaling pathways that are defined by components that include the five G protein-coupled melanocortin receptors; peptide agonists derived from the proopiomelanocortin preprohormone precursor; and the endogenous antagonists, agouti and agouti-related protein. This signaling system regulates a remarkably diverse array of physiological functions including pigmentation, adrenocortical steroidogenesis, energy homeostasis, natriuresis, erectile responses, energy homeostasis, and exocrine gland secretion. There are many complex and unique aspects of melanocortin signaling, such as the existence of endogenous antagonists, the agouti proteins, that act at three of the five melanocortin receptors. However, there is an aspect of melanocortin signaling that has facilitated highly reductionist approaches aimed at understanding the physiological functions of each receptor and peptide: in contrast to many peptides, the melanocortin agonists and antagonists are expressed in a limited number of very discrete locations. Similarly, the melanocortin receptors are also expressed in a limited number of discrete locations where they tend to be involved in rather circumscribed physiological functions. This review examines my laboratory's participation in the cloning of the melanocortin receptors and characterization of their physiological roles.
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Affiliation(s)
- Roger D Cone
- Center for the Study of Weight Regulation and Associated Disorders, and Vollum Institute, Oregon Health and Science University, Portland, Oregon 97239-3098, USA.
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