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Ma S, Yin X, Pin JP, Rondard P, Yi P, Liu J. Absence of calcium-sensing receptor basal activity due to inter-subunit disulfide bridges. Commun Biol 2024; 7:501. [PMID: 38664468 PMCID: PMC11045811 DOI: 10.1038/s42003-024-06189-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 04/12/2024] [Indexed: 04/28/2024] Open
Abstract
G protein-coupled receptors naturally oscillate between inactive and active states, often resulting in receptor constitutive activity with important physiological consequences. Among the class C G protein-coupled receptors that typically sense amino-acids and their derivatives, the calcium sensing receptor (CaSR) tightly controls blood calcium levels. Its constitutive activity has not yet been studied. Here, we demonstrate the importance of the inter-subunit disulfide bridges in maintaining the inactive state of CaSR, resulting in undetectable constitutive activity, unlike the other class C receptors. Deletion of these disulfide bridges results in strong constitutive activity that is abolished by mutations preventing amino acid binding. It shows that this inter-subunit disulfide link is necessary to limit the agonist effect of amino acids on CaSR. Furthermore, human genetic mutations deleting these bridges and associated with hypocalcemia result in elevated CaSR constitutive activity. These results highlight the physiological importance of fine tuning the constitutive activity of G protein-coupled receptors.
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Affiliation(s)
- Shumin Ma
- Cellular Signaling Laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Xueliang Yin
- Cellular Signaling Laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Jean-Philippe Pin
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, Montpellier, Cedex 5, France
| | - Philippe Rondard
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, Montpellier, Cedex 5, France.
| | - Ping Yi
- Cellular Signaling Laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China.
| | - Jianfeng Liu
- Cellular Signaling Laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China.
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2
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Orlandi P, Banchi M, Vaglini F, Carli M, Aringhieri S, Bandini A, Pardini C, Viaggi C, Lai M, Alì G, Ottani A, Vandini E, Guidi P, Bernardeschi M, La Rocca V, Francia G, Fontanini G, Pistello M, Frenzilli G, Giuliani D, Scarselli M, Bocci G. Melanocortin receptor 4 as a new target in melanoma therapy: Anticancer activity of the inhibitor ML00253764 alone and in association with B-raf inhibitor vemurafenib. Biochem Pharmacol 2024; 219:115952. [PMID: 38036189 DOI: 10.1016/j.bcp.2023.115952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2023] [Accepted: 11/27/2023] [Indexed: 12/02/2023]
Abstract
The aim of our study is to investigate in vitro and in vivo MC4R as a novel target in melanoma using the selective antagonist ML00253764 (ML) alone and in combination with vemurafenib, a B-rafV600E inhibitor. The human melanoma B-raf mutated A-2058 and WM 266-4 cell lines were used. An MC4R null A-2058 cell line was generated using a CRISPR/Cas9 system. MC4R protein expression was analysed by western blotting, immunohistochemistry, and immunofluorescence. Proliferation and apoptotic assays were performed with ML00253764, whereas the synergism with vemurafenib was evaluated by the combination index (CI) and Loewe methods. ERK1/2 phosphorylation and BCL-XL expression were quantified by western blot. In vivo experiments were performed in Athymic Nude-Foxn1nu male mice, injecting subcutaneously melanoma cells, and treating animals with ML, vemurafenib and their concomitant combination. Comet and cytome assays were performed. Our results show that human melanoma cell lines A-2058 and WM 266-4, and melanoma human tissue, express functional MC4R receptors on their surface. MC4R receptors on melanoma cells can be inhibited by the selective antagonist ML, causing antiproliferative and proapoptotic activity through the inhibition of phosphorylation of ERK1/2 and a reduction of BCL-XL. The concomitant combination of vemurafenib and ML caused a synergistic effect on melanoma cells in vitro and inhibited in vivo tumor growth in a preclinical model, without causing mouse weight loss or genotoxicity. Our original research contributes to the landscape of pharmacological treatments for melanoma, providing MC4R antagonists as drugs that can be added to established therapies.
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Affiliation(s)
- Paola Orlandi
- Dipartimento di Medicina Clinica e Sperimentale, Università di Pisa, Pisa, Italy
| | - Marta Banchi
- Dipartimento di Medicina Clinica e Sperimentale, Università di Pisa, Pisa, Italy
| | - Francesca Vaglini
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Pisa, Italy
| | - Marco Carli
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Pisa, Italy
| | - Stefano Aringhieri
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Pisa, Italy
| | - Arianna Bandini
- Dipartimento di Medicina Clinica e Sperimentale, Università di Pisa, Pisa, Italy
| | - Carla Pardini
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Pisa, Italy
| | - Cristina Viaggi
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Pisa, Italy
| | - Michele Lai
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Pisa, Italy
| | - Greta Alì
- Dipartimento di Patologia Chirurgica, Medica, Molecolare e dell'Area Critica, Università di Pisa, Pisa, Italy
| | - Alessandra Ottani
- Dipartimento di Scienze Biomediche, Metaboliche e Neuroscienze, Sezione di Farmacologia e Medicina Molecolare, Università di Modena e Reggio Emilia, Modena, Italy
| | - Eleonora Vandini
- Dipartimento di Scienze Biomediche, Metaboliche e Neuroscienze, Sezione di Farmacologia e Medicina Molecolare, Università di Modena e Reggio Emilia, Modena, Italy
| | - Patrizia Guidi
- Dipartimento di Medicina Clinica e Sperimentale, Università di Pisa, Pisa, Italy
| | | | - Veronica La Rocca
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Pisa, Italy; Scuola Superiore Sant'Anna, Pisa, Italy
| | - Giulio Francia
- Border Biomedical Research Center, University of Texas at El Paso (UTEP), El Paso, TX, USA
| | - Gabriella Fontanini
- Dipartimento di Patologia Chirurgica, Medica, Molecolare e dell'Area Critica, Università di Pisa, Pisa, Italy
| | - Mauro Pistello
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Pisa, Italy
| | - Giada Frenzilli
- Dipartimento di Medicina Clinica e Sperimentale, Università di Pisa, Pisa, Italy
| | - Daniela Giuliani
- Dipartimento di Scienze Biomediche, Metaboliche e Neuroscienze, Sezione di Farmacologia e Medicina Molecolare, Università di Modena e Reggio Emilia, Modena, Italy
| | - Marco Scarselli
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Pisa, Italy
| | - Guido Bocci
- Dipartimento di Medicina Clinica e Sperimentale, Università di Pisa, Pisa, Italy.
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3
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Ji RL, Liu T, Hou ZS, Wen HS, Tao YX. Divergent Pharmacology and Biased Signaling of the Four Melanocortin-4 Receptor Isoforms in Rainbow Trout ( Oncorhynchus mykiss). Biomolecules 2023; 13:1248. [PMID: 37627313 PMCID: PMC10452266 DOI: 10.3390/biom13081248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 08/13/2023] [Accepted: 08/14/2023] [Indexed: 08/27/2023] Open
Abstract
The melanocortin-4 receptor (MC4R) is essential for the modulation of energy balance and reproduction in both fish and mammals. Rainbow trout (Oncorhynchus mykiss) has been extensively studied in various fields and provides a unique opportunity to investigate divergent physiological roles of paralogues. Herein we identified four trout mc4r (mc4ra1, mc4ra2, mc4rb1, and mc4rb2) genes. Four trout Mc4rs (omMc4rs) were homologous to those of teleost and mammalian MC4Rs. Multiple sequence alignments, a phylogenetic tree, chromosomal synteny analyses, and pharmacological studies showed that trout mc4r genes may have undergone different evolutionary processes. All four trout Mc4rs bound to two peptide agonists and elevated intracellular cAMP levels dose-dependently. High basal cAMP levels were observed at two omMc4rs, which were decreased by Agouti-related peptide. Only omMc4rb2 was constitutively active in the ERK1/2 signaling pathway. Ipsen 5i, ML00253764, and MCL0020 were biased allosteric modulators of omMc4rb1 with selective activation upon ERK1/2 signaling. ML00253764 behaved as an allosteric agonist in Gs-cAMP signaling of omMc4rb2. This study will lay the foundation for future physiological studies of various mc4r paralogs and reveal the evolution of MC4R in vertebrates.
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Affiliation(s)
- Ren-Lei Ji
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA; (R.-L.J.); (T.L.)
| | - Ting Liu
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA; (R.-L.J.); (T.L.)
| | - Zhi-Shuai Hou
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA; (R.-L.J.); (T.L.)
| | - Hai-Shen Wen
- The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266100, China;
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA; (R.-L.J.); (T.L.)
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4
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Botha R, Kumar SS, Grimsey NL, Mountjoy KG. A unique melanocortin-4-receptor signaling profile for obesity-associated constitutively active variants. J Mol Endocrinol 2023; 71:e230008. [PMID: 37040537 PMCID: PMC10304906 DOI: 10.1530/jme-23-0008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 04/11/2023] [Indexed: 04/13/2023]
Abstract
The melanocortin-4 receptor (MC4R) plays a critical role in regulating energy homeostasis. Studies on obesogenic human MC4R (hMC4R) variants have not yet revealed how hMC4R maintains body weight. Here, we identified a signaling profile for obesogenic constitutively active H76R and L250Q hMC4R variants transfected in HEK293 cells that included constitutive activity for adenylyl cyclase (AC), cyclic adenosine monophosphate (cAMP) response element (CRE)-driven transcription, and calcium mobilization but not phosphorylated extracellular signal-regulated kinase 1/2 (pERK1/2) activity. Importantly, the signaling profile included impaired α-melanocyte-stimulating hormone-induced CRE-driven transcription but not impaired α-melanocyte-stimulating hormone-induced AC, calcium, or pERK1/2. This profile was not observed for transfected H158R, a constitutively active hMC4R variant associated with overweight but not obesity. We concluded that there is potential for α-melanocyte-stimulating hormone-induced CRE-driven transcription in HEK293 cells transfected with obesogenic hMC4R variants to be the key predictive tool for determining whether they exhibit loss of function. Furthermore, in vivo, α-melanocyte-stimulating hormone-induced hMC4R CRE-driven transcription may be key for maintaining body weight.
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Affiliation(s)
- Rikus Botha
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, New Zealand
| | - Shree S Kumar
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, New Zealand
| | - Natasha L Grimsey
- Department of Pharmacology, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, New Zealand
- Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, New Zealand
- Maurice Wilkins Centre for Biodiscovery, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, New Zealand
| | - Kathleen G Mountjoy
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, New Zealand
- Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, New Zealand
- Maurice Wilkins Centre for Biodiscovery, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, New Zealand
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, New Zealand
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5
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Ji RL, Jiang SS, Tao YX. Modulation of Canine Melanocortin-3 and -4 Receptors by Melanocortin-2 Receptor Accessory Protein 1 and 2. Biomolecules 2022; 12:biom12111608. [PMID: 36358958 PMCID: PMC9687446 DOI: 10.3390/biom12111608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 10/26/2022] [Accepted: 10/29/2022] [Indexed: 11/06/2022] Open
Abstract
The neural melanocortin receptors (MCRs), melanocortin-3 and -4 receptors (MC3R and MC4R), have crucial roles in regulating energy homeostasis. The melanocortin-2 receptor accessory proteins (MRAPs, MRAP1 and MRAP2) have been shown to regulate neural MCRs in a species-specific manner. The potential effects of MRAP1 and MRAP2 on canine neural MCRs have not been investigated before. Herein, we cloned canine (c) MC3R and identified one canine MRAP2 splice variant, MRAP2b, with N-terminal extension of cMRAP2a. Canine MC3R showed higher maximal responses to five agonists than those of human MC3R. We further investigated the modulation of cMRAP1, cMRAP2a, and cMRAP2b, on cMC3R and cMC4R pharmacology. For the cMC3R, all MRAPs had no effect on trafficking; cMRAP1 significantly decreased Bmax whereas cMRAP2a and cMRAP2b significantly increased Bmax. Both MRAP1 and MRAP2a decreased Rmaxs in response to α-MSH and ACTH; MRAP2b only decreased α-MSH-stimulated cAMP generation. For the MC4R, MRAP1 and MRAP2a increased cell surface expression, and MRAP1 and MRAP2a increased Bmaxs. All MRAPs had increased affinities to α-MSH and ACTH. MRAP2a increased ACTH-induced cAMP levels, whereas MRAP2b decreased α-MSH- and ACTH-stimulated cAMP production. These findings may lead to a better understanding of the regulation of neural MCRs by MRAP1 and MRAP2s.
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6
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Yuan XC, Tao YX. Ligands for Melanocortin Receptors: Beyond Melanocyte-Stimulating Hormones and Adrenocorticotropin. Biomolecules 2022; 12:biom12101407. [PMID: 36291616 PMCID: PMC9599618 DOI: 10.3390/biom12101407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 09/25/2022] [Accepted: 09/28/2022] [Indexed: 11/16/2022] Open
Abstract
The discovery of melanocortins in 1916 has resulted in more than 100 years of research focused on these peptides. Extensive studies have elucidated well-established functions of melanocortins mediated by cell surface receptors, including MSHR (melanocyte-stimulating hormone receptor) and ACTHR (adrenocorticotropin receptor). Subsequently, three additional melanocortin receptors (MCRs) were identified. Among these five MCRs, MC3R and MC4R are expressed primarily in the central nervous system, and are therefore referred to as the neural MCRs. Since the central melanocortin system plays important roles in regulating energy homeostasis, targeting neural MCRs is emerging as a therapeutic approach for treating metabolic conditions such as obesity and cachexia. Early efforts modifying endogenous ligands resulted in the development of many potent and selective ligands. This review focuses on the ligands for neural MCRs, including classical ligands (MSH and agouti-related peptide), nonclassical ligands (lipocalin 2, β-defensin, small molecules, and pharmacoperones), and clinically approved ligands (ACTH, setmelanotide, bremelanotide, and several repurposed drugs).
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Affiliation(s)
- Xiao-Chen Yuan
- College of Animal Science and Technology, Anhui Agricultural University, Hefei 230061, China
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA
- Correspondence:
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7
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Amorim MR, Aung O, Mokhlesi B, Polotsky VY. Leptin-mediated neural targets in obesity hypoventilation syndrome. Sleep 2022; 45:zsac153. [PMID: 35778900 PMCID: PMC9453616 DOI: 10.1093/sleep/zsac153] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 06/20/2022] [Indexed: 07/30/2023] Open
Abstract
Obesity hypoventilation syndrome (OHS) is defined as daytime hypercapnia in obese individuals in the absence of other underlying causes. In the United States, OHS is present in 10%-20% of obese patients with obstructive sleep apnea and is linked to hypoventilation during sleep. OHS leads to high cardiorespiratory morbidity and mortality, and there is no effective pharmacotherapy. The depressed hypercapnic ventilatory response plays a key role in OHS. The pathogenesis of OHS has been linked to resistance to an adipocyte-produced hormone, leptin, a major regulator of metabolism and control of breathing. Mechanisms by which leptin modulates the control of breathing are potential targets for novel therapeutic strategies in OHS. Recent advances shed light on the molecular pathways related to the central chemoreceptor function in health and disease. Leptin signaling in the nucleus of the solitary tract, retrotrapezoid nucleus, hypoglossal nucleus, and dorsomedial hypothalamus, and anatomical projections from these nuclei to the respiratory control centers, may contribute to OHS. In this review, we describe current views on leptin-mediated mechanisms that regulate breathing and CO2 homeostasis with a focus on potential therapeutics for the treatment of OHS.
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Affiliation(s)
- Mateus R Amorim
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - O Aung
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Babak Mokhlesi
- Department of Internal Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, Rush University Medical Center, Chicago, IL, USA
| | - Vsevolod Y Polotsky
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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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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9
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Watts SW, Flood ED, Thompson JM. Is the 5-hydroxytryptamine 7 Receptor Constitutively Active in the Vasculature? A Study in Veins/Vein. J Cardiovasc Pharmacol 2022; 80:314-322. [PMID: 35939654 PMCID: PMC9373064 DOI: 10.1097/fjc.0000000000001296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 04/17/2022] [Indexed: 11/26/2022]
Abstract
ABSTRACT The 5-hydroxytryptamine 7 (5-HT 7 ) receptor is reported to have considerable constitutive activity when transfected into cells. Constitutive activity-receptor activity in the absence of known agonist-is important for understanding the contributions of a receptor to (patho)physiology. We test the hypothesis that the 5-HT 7 receptor possesses constitutive activity in a physiological situation. Isolated veins from male and female Sprague Dawley rats were used as models for measuring isometric force; the abdominal vena cava possesses a functional 5-HT 7 receptor that mediates relaxation, whereas the small mesenteric vein does not. Compounds reported to act as inverse agonists were investigated for their ability to cause contraction (moving a constitutively active relaxant receptor to an inactive state, removing relaxation). Compared with a vehicle control, clozapine, risperidone, ketanserin, and SB269970 caused no contraction in the isolated male abdominal vena cava. By contrast, methiothepin caused a concentration-dependent contraction of the male but not female abdominal vena cava, although with low potency (-log EC 50 [M] = 5.50 ± 0.45) and efficacy (∼12% of contraction to endothelin-1). Methiothepin-induced contraction was not reduced by the 5-HT 7 receptor antagonist (SB269970, 1 μM, not active in the vena cava). These same compounds showed little to no effect in the isolated mesenteric vein. We conclude that the 5-HT 7 receptor in the isolated veins of the Sprague Dawley rat does not possess constitutive activity. We raise the question of the physiological relevance of constitutive activity of this receptor important to such diverse physiological functions as sleep, circadian rhythm, temperature, and blood pressure regulation.
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Affiliation(s)
- Stephanie W Watts
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI
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10
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Oliveira V, Riedl RA, Claflin KE, Mathieu NM, Ritter ML, Balapattabi K, Wackman KK, Reho JJ, Brozoski DT, Morgan DA, Cui H, Rahmouni K, Burnett CML, Nakagawa P, Sigmund CD, Morselli LL, Grobe JL. Melanocortin MC 4R receptor is required for energy expenditure but not blood pressure effects of angiotensin II within the mouse brain. Physiol Genomics 2022; 54:196-205. [PMID: 35476598 PMCID: PMC9131927 DOI: 10.1152/physiolgenomics.00015.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The brain renin-angiotensin system (RAS) is implicated in control of blood pressure (BP), fluid intake, and energy expenditure (EE). Angiotensin II (ANG II) within the arcuate nucleus of the hypothalamus contributes to control of resting metabolic rate (RMR) and thereby EE through its actions on Agouti-related peptide (AgRP) neurons, which also contribute to EE control by leptin. First, we determined that although leptin stimulates EE in control littermates, mice with transgenic activation of the brain RAS (sRA) exhibit increased EE and leptin has no additive effect to exaggerate EE in these mice. These findings led us to hypothesize that leptin and ANG II in the brain stimulate EE through a shared mechanism. Because AgRP signaling to the melanocortin MC4R receptor contributes to the metabolic effects of leptin, we performed a series of studies examining RMR, fluid intake, and BP responses to ANG II in mice rendered deficient for expression of MC4R via a transcriptional block (Mc4r-TB). These mice were resistant to stimulation of RMR in response to activation of the endogenous brain RAS via chronic deoxycorticosterone acetate (DOCA)-salt treatment, whereas fluid and electrolyte effects remained intact. These mice were also resistant to stimulation of RMR via acute intracerebroventricular (ICV) injection of ANG II, whereas BP responses to ICV ANG II remained intact. Collectively, these data demonstrate that the effects of ANG II within the brain to control RMR and EE are dependent on MC4R signaling, whereas fluid homeostasis and BP responses are independent of MC4R signaling.
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Affiliation(s)
- Vanessa Oliveira
- 1Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Ruth A. Riedl
- 2Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Kristin E. Claflin
- 3Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, Iowa
| | - Natalia M. Mathieu
- 1Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - McKenzie L. Ritter
- 1Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | | | - Kelsey K. Wackman
- 1Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - John J. Reho
- 1Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin,4Comprehensive Rodent Metabolic Phenotyping Core, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Daniel T. Brozoski
- 1Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Donald A. Morgan
- 3Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, Iowa
| | - Huxing Cui
- 3Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, Iowa,5Obesity Research and Education Initiative, University of Iowa, Iowa City, Iowa
| | - Kamal Rahmouni
- 3Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, Iowa,5Obesity Research and Education Initiative, University of Iowa, Iowa City, Iowa,6Department of Internal Medicine, University of Iowa, Iowa City, Iowa,7Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa,8Iowa City Veterans Affairs Health Care System, Iowa City, Iowa
| | | | - Pablo Nakagawa
- 1Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin,9Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Curt D. Sigmund
- 1Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin,9Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin,10Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Lisa L. Morselli
- 11Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Justin L. Grobe
- 1Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin,4Comprehensive Rodent Metabolic Phenotyping Core, Medical College of Wisconsin, Milwaukee, Wisconsin,9Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin,10Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin,12Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, Wisconsin
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Tao YX. Mutations in melanocortin-4 receptor: From fish to men. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2022; 189:215-257. [PMID: 35595350 DOI: 10.1016/bs.pmbts.2022.03.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Melanocortin-4 receptor (MC4R), expressed abundantly in the hypothalamus, is a critical regulator of energy homeostasis, including both food intake and energy expenditure. Shortly after the publication in 1997 of the Mc4r knockout phenotypes in mice, including increased food intake and severe obesity, the first mutations in MC4R were reported in humans in 1998. Studies in the subsequent two decades have established MC4R mutation as the most common monogenic form of obesity, especially in early-onset severe obesity. Studies in animals, from fish to mammals, have established the conserved physiological roles of MC4R in all vertebrates in regulating energy balance. Drug targeting MC4R has been recently approved for treating morbid genetic obesity. How the MC4R can be exploited for animal production is highly worthy of active investigation.
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Affiliation(s)
- Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States.
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12
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Ji RL, Tao YX. Melanocortin-1 receptor mutations and pigmentation: Insights from large animals. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2022; 189:179-213. [PMID: 35595349 DOI: 10.1016/bs.pmbts.2022.03.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The melanocortin-1 receptor (MC1R) is a G protein-coupled receptor expressed in cutaneous and hair follicle melanocytes, and plays a central role in coat color determination in vertebrates. Numerous MC1R variants have been identified in diverse species. Some of these variants have been associated with specific hair and skin color phenotypes in humans as well as coat color in animals. Gain-of-function mutations of the MC1R gene cause dominant or partially dominant black/dark coat color, and loss-of-function mutations of the MC1R gene cause recessive or partially recessive red/yellow/pale coat color phenotypes. These have been well documented in a large number of mammals, including human, dog, cattle, horse, sheep, pig, and fox. Higher similarities between large mammals and humans makes them better models to understand pathogenesis of human diseases caused by MC1R mutations. High identities in MC1Rs and similar variants identified in both humans and large mammals also provide an opportunity for receptor structure and function study. In this review, we aim to summarize the naturally occurring mutations of MC1R in humans and large animals.
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Affiliation(s)
- Ren-Lei Ji
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States.
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Wang X, Xue S, Lei X, Song W, Li L, Li X, Fu Y, Zhang C, Zhang H, Luo Y, Wang M, Lin G, Zhang C, Guo J. Pharmacological Evaluation of Melanocortin 2 Receptor Accessory Protein 2 on Axolotl Neural Melanocortin Signaling. Front Endocrinol (Lausanne) 2022; 13:820896. [PMID: 35250878 PMCID: PMC8891371 DOI: 10.3389/fendo.2022.820896] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 01/05/2022] [Indexed: 01/14/2023] Open
Abstract
The Melanocortin-3 receptor (MC3R) and Melanocortin-4 receptor (MC4R), two members of the key hypothalamic neuropeptide signaling, function as complex mediators to control the central appetitive and energy homeostasis. The melanocortin 2 receptor accessory protein 2 (MRAP2) is well-known for its modulation on the trafficking and signaling of MC3R and MC4R in mammals. In this study, we cloned and elucidated the pharmacological profiles of MRAP2 on the regulation of central melanocortin signaling in a relatively primitive poikilotherm amphibian species, the Mexican axolotl (Ambystoma mexicanum). Our results showed the higher conservation of axolotl mc3r and mc4r across species than mrap2, especially the transmembrane regions in these proteins. Phylogenetic analysis indicated that the axolotl MC3R/MC4R clustered closer to their counterparts in the clawed frog, whereas MRAP2 fell in between the reptile and amphibian clade. We also identified a clear co-expression of mc3r, mc4r, and mrap2 along with pomc and agrp in the axolotl brain tissue. In the presence of MRAP2, the pharmacological stimulation of MC3R by α-MSH or ACTH significantly decreased. MRAP2 significantly decreased the cell surface expression of MC4R in a dose dependent manner. The co-localization and formation of the functional complex of axolotl MC3R/MC4R and MRAP2 on the plasma membrane were further confirmed in vitro. Dramatic changes of the expression levels of mc3r, mrap2, pomc, and agrp in the fasting axolotl hypothalamus indicated their critical roles in the metabolic regulation of feeding behavior and energy homeostasis in the poikilotherm aquatic amphibian.
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Affiliation(s)
- Xiaozhu Wang
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Song Xue
- 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
| | - Xiaowei Lei
- 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
| | - Wenqi Song
- 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
- Department of Plastic and Reconstructive Surgery, Shanghai Institute of Precision Medicine, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xuan 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
| | - Yanbin Fu
- 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
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Hailin 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
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Yao Luo
- 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
| | - Meng Wang
- Department of Plastic and Reconstructive Surgery, Shanghai Institute of Precision Medicine, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Gufa Lin
- 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
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, 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
| | - Jing Guo
- Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
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Ji RL, Tao YX. Regulation of Melanocortin-3 and -4 Receptors by Isoforms of Melanocortin-2 Receptor Accessory Protein 1 and 2. Biomolecules 2022; 12:biom12020244. [PMID: 35204745 PMCID: PMC8961526 DOI: 10.3390/biom12020244] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 01/31/2022] [Accepted: 02/01/2022] [Indexed: 01/27/2023] Open
Abstract
The neural melanocortin receptors (MCRs), melanocortin-3 and -4 receptors (MC3R and MC4R), play essential non-redundant roles in the regulation of energy homeostasis. Interaction of neural MCRs and melanocortin-2 receptor accessory proteins (MRAPs, MRAP1 and MRAP2) is suggested to play pivotal roles in MC3R and MC4R signaling. In the present study, we identified two new human (h) MRAP2 splice variants, MRAP2b (465 bp open reading frame) and MRAP2c (381 bp open reading frame). Human MRAP2s are different in C-termini. We investigated the effects of five isoforms of MRAPs, hMRAP1a, hMRAP1b, hMRAP2a, hMRAP2b, and hMRAP2c, on MC3R and MC4R pharmacology. At the hMC3R, hMRAP1a and hMRAP2c increased and hMRAP1b decreased the cell surface expression. hMRAP1a increased affinity to ACTH. Four MRAPs (hMRAP1a, hMRAP1b, hMRAP2a, and hMRAP2c) decreased the maximal responses in response to α-MSH and ACTH. For hMC4R, hMRAP1a, hMRAP2a, and hMRAP2c increased the cell surface expression of hMC4R. Human MRAP1b significantly increased affinity to ACTH while MRAP2a decreased affinity to ACTH. Human MRAP1a increased ACTH potency. MRAPs also affected hMC4R basal activities, with hMRAP1s increasing and hMRAP2s decreasing the basal activities. In summary, the newly identified splicing variants, hMRAP2b and hMRAP2c, could regulate MC3R and MC4R pharmacology. The two MRAP1s and three MRAP2s had differential effects on MC3R and MC4R trafficking, binding, and signaling. These findings led to a better understanding of the regulation of neural MCRs by MRAP1s and MRAP2s.
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Abstract
In a new paper, Wade et al. (2021) analyzed the frequency of MC4R loss-of-function (LoF) mutations in a population-based Avon Longitudinal Study of Parents and Children. The frequency was 1 in 337 and the authors showed that MC4R LoF variants significantly correlated with increased body weight and fat mass in children and adults (cumulating in additional 17.76 kg weight in adulthood). Hence, the authors provide evidence that MC4R LoF variants are more common than previously expected.
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Affiliation(s)
- Peter Kühnen
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin und Humboldt-Universität zu Berlin, Institute for Experimental Pediatric Endocrinology, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Heike Biebermann
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin und Humboldt-Universität zu Berlin, Institute for Experimental Pediatric Endocrinology, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Heiko Krude
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin und Humboldt-Universität zu Berlin, Institute for Experimental Pediatric Endocrinology, Augustenburger Platz 1, 13353 Berlin, Germany.
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16
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Oliveira V, Kwitek AE, Sigmund CD, Morselli LL, Grobe JL. Recent Advances in Hypertension: Intersection of Metabolic and Blood Pressure Regulatory Circuits in the Central Nervous System. Hypertension 2021; 77:1061-1068. [PMID: 33611936 DOI: 10.1161/hypertensionaha.120.14513] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Obesity represents the single greatest ongoing roadblock to improving cardiovascular health. Prolonged obesity is associated with fundamental changes in the integrative control of energy balance, including the development of selective leptin resistance, which is thought to contribute to obesity-associated hypertension, and adaptation of resting metabolic rate (RMR) when excess weight is reduced. Leptin and the melanocortin system within the hypothalamus contribute to the control of both energy balance and blood pressure. While the development of drugs to stimulate RMR and thereby reverse obesity through activation of the melanocortin system has been pursued, most of the resulting compounds simultaneously cause hypertension. Evidence supports the concept that although feeding behaviors, RMR, and blood pressure are controlled through mechanisms that utilize similar molecular mediators, these mechanisms exist in anatomically dissociable networks. New evidence supports a major change in molecular signaling within AgRP (Agouti-related peptide) neurons of the arcuate nucleus of the hypothalamus during prolonged obesity and the existence of multiple distinct subtypes of AgRP neurons that individually contribute to control of feeding, RMR, or blood pressure. Finally, ongoing work by our laboratory and others support a unique role for AT1 (angiotensin II type 1 receptor) within one specific subtype of AgRP neuron for the control of RMR. We propose that understanding the unique biology of the AT1-expressing, RMR-controlling subtype of AgRP neurons will help to resolve the selective dysfunctions in RMR control that develop during prolonged obesity and potentially point toward novel druggable antiobesity targets that will not simultaneously cause hypertension.
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Affiliation(s)
- Vanessa Oliveira
- From the Department of Physiology (V.O., A.E.K., C.D.S., J.L.G.), Medical College of Wisconsin, Milwaukee
| | - Anne E Kwitek
- From the Department of Physiology (V.O., A.E.K., C.D.S., J.L.G.), Medical College of Wisconsin, Milwaukee.,Cardiovascular Center (A.E.K., C.D.S., L.L.M., J.L.G.), Medical College of Wisconsin, Milwaukee
| | - Curt D Sigmund
- From the Department of Physiology (V.O., A.E.K., C.D.S., J.L.G.), Medical College of Wisconsin, Milwaukee.,Cardiovascular Center (A.E.K., C.D.S., L.L.M., J.L.G.), Medical College of Wisconsin, Milwaukee.,Neuroscience Research Center (C.D.S., J.L.G.), Medical College of Wisconsin, Milwaukee
| | - Lisa L Morselli
- Cardiovascular Center (A.E.K., C.D.S., L.L.M., J.L.G.), Medical College of Wisconsin, Milwaukee.,Division of Endocrinology and Molecular Medicine, Department of Medicine (L.L.M.), Medical College of Wisconsin, Milwaukee
| | - Justin L Grobe
- From the Department of Physiology (V.O., A.E.K., C.D.S., J.L.G.), Medical College of Wisconsin, Milwaukee.,Cardiovascular Center (A.E.K., C.D.S., L.L.M., J.L.G.), Medical College of Wisconsin, Milwaukee.,Neuroscience Research Center (C.D.S., J.L.G.), Medical College of Wisconsin, Milwaukee.,Department of Biomedical Engineering (J.L.G.), Medical College of Wisconsin, Milwaukee.,Comprehensive Rodent Metabolic Phenotyping Core (J.L.G.), Medical College of Wisconsin, Milwaukee
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17
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Wang M, Pi L, Lei X, Li L, Xu J, Kuang Z, Zhang C, Li L, Zhang C. Functional Characterization of the Internal Symmetry of MRAP2 Antiparallel Homodimer. Front Endocrinol (Lausanne) 2021; 12:750797. [PMID: 34759891 PMCID: PMC8572914 DOI: 10.3389/fendo.2021.750797] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 09/30/2021] [Indexed: 11/19/2022] Open
Abstract
The melanocortin receptors are defined as a series of vital pharmaceutical targets to regulate neuronal appetite and maintain controllable body weight for mammals and teleosts. Melanocortin receptor accessory protein 2 (MRAP2) functions as an essential accessory player that modulates the surface translocation and binding to a variety of endogenous or synthetic hormones of central melanocortin-4 receptor (MC4R) signaling. MRAP2 is a single-transmembrane protein and could form a functional symmetric antiparallel homodimer topology. Here, we inverted the N-terminal, transmembrane, and C-terminal domains and generated six distinct conformational variants of the mouse MRAP2 to explore the functional orientations and the internal symmetry of MRAP2 dimers. These remolded MRAP2 mutants showed proper assembly of the antiparallel homodimer and binding to the MC4R, but slightly altered the regulatory profile on the surface expression and the ligand-stimulated cAMP cascades of MC4R. This study elucidated the importance of the orientation of each domain of the single-transmembrane protein and revealed the pharmacological properties of the internal symmetry of the antiparallel homodimer for MRAP2.
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Affiliation(s)
- Meng Wang
- Department of Plastic and Reconstructive Surgery, Shanghai Institute of Precision Medicine, Shanghai Ninth People’s Hospital, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Linyu Pi
- Department of Plastic and Reconstructive Surgery, Shanghai Institute of Precision Medicine, Shanghai Ninth People’s Hospital, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiaowei Lei
- 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
- Department of Plastic and Reconstructive Surgery, Shanghai Institute of Precision Medicine, Shanghai Ninth People’s Hospital, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jing 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
| | - Zhe Kuang
- 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
- Department of Plastic and Reconstructive Surgery, Shanghai Institute of Precision Medicine, Shanghai Ninth People’s Hospital, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Liang Li
- Department of Thyroid and Breast Surgery, ZiBo Central Hospital Affiliated of Binzhou Medical University, Zibo, China
- *Correspondence: Liang Li, ; Chao Zhang,
| | - Chao Zhang
- Department of Plastic and Reconstructive Surgery, Shanghai Institute of Precision Medicine, Shanghai Ninth People’s Hospital, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- *Correspondence: Liang Li, ; Chao Zhang,
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18
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Yang LK, Hou ZS, Tao YX. Biased signaling in naturally occurring mutations of G protein-coupled receptors associated with diverse human diseases. Biochim Biophys Acta Mol Basis Dis 2021; 1867:165973. [PMID: 32949766 PMCID: PMC7722056 DOI: 10.1016/j.bbadis.2020.165973] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 09/07/2020] [Accepted: 09/14/2020] [Indexed: 12/15/2022]
Abstract
G protein-coupled receptors (GPCRs) play critical roles in transmitting a variety of extracellular signals into the cells and regulate diverse physiological functions. Naturally occurring mutations that result in dysfunctions of GPCRs have been known as the causes of numerous diseases. Significant progresses have been made in elucidating the pathophysiology of diseases caused by mutations. The multiple intracellular signaling pathways, such as G protein-dependent and β-arrestin-dependent signaling, in conjunction with recent advances on biased agonism, have broadened the view on the molecular mechanism of disease pathogenesis. This review aims to briefly discuss biased agonism of GPCRs (biased ligands and biased receptors), summarize the naturally occurring GPCR mutations that cause biased signaling, and propose the potential pathophysiological relevance of biased mutant GPCRs associated with various endocrine diseases.
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Affiliation(s)
- Li-Kun Yang
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States
| | - Zhi-Shuai Hou
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States.
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Yang LK, Tao YX. Alanine Scanning Mutagenesis of the DRYxxI Motif and Intracellular Loop 2 of Human Melanocortin-4 Receptor. Int J Mol Sci 2020; 21:ijms21207611. [PMID: 33076233 PMCID: PMC7589821 DOI: 10.3390/ijms21207611] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 10/10/2020] [Accepted: 10/11/2020] [Indexed: 12/15/2022] Open
Abstract
The melanocortin-4 receptor (MC4R) is a member of the G-protein-coupled receptor (GPCR) superfamily, which has been extensively studied in obesity pathogenesis due to its critical role in regulating energy homeostasis. Both the Gs-cAMP and ERK1/2 cascades are known as important intracellular signaling pathways initiated by the MC4R. The DRYxxI motif at the end of transmembrane domain 3 and the intracellular loop 2 (ICL2) are thought to be crucial for receptor function in several GPCRs. To study the functions of this domain in MC4R, we performed alanine-scanning mutagenesis on seventeen residues. We showed that one residue was critical for receptor cell surface expression. Eight residues were important for ligand binding. Mutations of three residues impaired Gs-cAMP signaling without changing the binding properties. Investigation on constitutive activities of all the mutants in the cAMP pathway revealed that six residues were involved in constraining the receptor in inactive states and five residues were important for receptor activation in the absence of an agonist. In addition, mutations of four residues impaired the ligand-stimulated ERK1/2 signaling pathway without affecting the binding properties. We also showed that some mutants were biased to the Gs-cAMP or ERK1/2 signaling pathway. In summary, we demonstrated that the DRYxxI motif and ICL2 were important for MC4R function.
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Yang Z, Liang XF, Li GL, Tao YX. Biased signaling in fish melanocortin-4 receptors (MC4Rs): Divergent pharmacology of four ligands on spotted scat (Scatophagus argus) and grass carp (Ctenopharyngodon idella) MC4Rs. Mol Cell Endocrinol 2020; 515:110929. [PMID: 32615281 DOI: 10.1016/j.mce.2020.110929] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 06/19/2020] [Accepted: 06/24/2020] [Indexed: 12/24/2022]
Abstract
The melanocortin-4 receptor (MC4R) plays a critical role in the regulation of energy homeostasis in both mammals and fish. Several fish MC4Rs recently characterized have high constitutive activities, potentially associated with food intake and growth rate. In the present study, we systematically investigated the effects of four human MC4R (hMC4R) antagonists, including agouti-related peptide (AgRP), Ipsen 5i, ML00253764, and MCL0020, on the cAMP and ERK1/2 signaling of two fish MC4Rs: spotted scat (Scatophagus argus) MC4R (saMC4R) and grass carp (Ctenopharyngodon idella) MC4R (ciMC4R), with hMC4R as a control. We showed that both saMC4R and ciMC4R were constitutively active with significantly increased basal cAMP levels. AgRP acted as an inverse agonist in cAMP signaling pathway in both fish MC4Rs whereas MCL0020 functioned as an inverse agonist for ciMC4R but a weak neutral antagonist for saMC4R. Ipsen 5i and MCL0020 behaved as neutral allosteric modulators in the cAMP signaling of fish MC4Rs. The saMC4R and ciMC4R had similar basal pERK1/2 levels as hMC4R and the pERK1/2 levels of the two fish MC4Rs were significantly increased upon stimulation with all four ligands. In summary, our studies demonstrated the existence of biased signaling in fish MC4R. We also showed dramatic pharmacological differences of human and fish MC4Rs with synthetic ligands. Our data provided novel insights and led to a better understanding of fish MC4R pharmacology.
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Affiliation(s)
- Zhao Yang
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, 36849, United States
| | - Xu-Fang Liang
- College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Hubei Collaborative Innovation Center for Freshwater Aquaculture, Wuhan, Hubei, 430070, China
| | - Guang-Li Li
- Fisheries College, Guangdong Ocean University, Zhanjiang, 524088, 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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21
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Obesity treatment effect in Danish children and adolescents carrying Melanocortin-4 Receptor mutations. Int J Obes (Lond) 2020; 45:66-76. [PMID: 32921795 PMCID: PMC7752754 DOI: 10.1038/s41366-020-00673-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 08/10/2020] [Accepted: 09/03/2020] [Indexed: 11/20/2022]
Abstract
Objectives To determine the prevalence of Melanocortin-4 Receptor (MC4R) mutations in a cohort of children and adolescents with overweight or obesity and to determine whether treatment responses differed between carriers and noncarriers. Methods Using target region capture sequencing, an MC4R mutation screen was performed in 1261 Danish children and adolescents enrolled at a tertiary multidisciplinary childhood obesity treatment center. Measurements of anthropometrics, blood pressure, fasting blood biochemistry including lipid and hormone levels, and dual-energy X-ray absorptiometry were performed at baseline and throughout treatment. Results Of 1209 children and adolescents that met all criteria to be included in the described analyses, 30 (2.5%) carried damaging or unresolved MC4R mutations. At baseline, mutation carriers exhibited higher concentrations of plasma thyroid-stimulating hormone (p = 0.003), and lower concentrations of plasma thyroxine (p = 0.010) compared to noncarriers. After a median of 1 year of treatment (range 0.5–4.0 years), body mass index (BMI) standard deviation score (SDS) was reduced in noncarriers but not in carriers, and this difference in treatment response was statistically significant (p = 0.005). Furthermore, HDL cholesterol was reduced in carriers, a response significantly different from that of noncarriers (p = 0.017). Conclusion Among Danish children and adolescents with overweight or obesity entering a tertiary lifestyle intervention, 2.5% carried damaging or unresolved MC4R mutations. In contrast to noncarriers, carriers of damaging or unresolved MC4R mutations failed to reduce their BMI SDS during obesity treatment, indicating a need for personalized treatment based on the MC4R genotype.
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22
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Structural Complexity and Plasticity of Signaling Regulation at the Melanocortin-4 Receptor. Int J Mol Sci 2020; 21:ijms21165728. [PMID: 32785054 PMCID: PMC7460885 DOI: 10.3390/ijms21165728] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 08/03/2020] [Accepted: 08/06/2020] [Indexed: 02/06/2023] Open
Abstract
The melanocortin-4 receptor (MC4R) is a class A G protein-coupled receptor (GPCR), essential for regulation of appetite and metabolism. Pathogenic inactivating MC4R mutations are the most frequent cause of monogenic obesity, a growing medical and socioeconomic problem worldwide. The MC4R mediates either ligand-independent or ligand-dependent signaling. Agonists such as α-melanocyte-stimulating hormone (α-MSH) induce anorexigenic effects, in contrast to the endogenous inverse agonist agouti-related peptide (AgRP), which causes orexigenic effects by suppressing high basal signaling activity. Agonist action triggers the binding of different subtypes of G proteins and arrestins, leading to concomitant induction of diverse intracellular signaling cascades. An increasing number of experimental studies have unraveled molecular properties and mechanisms of MC4R signal transduction related to physiological and pathophysiological aspects. In addition, the MC4R crystal structure was recently determined at 2.75 Å resolution in an inactive state bound with a peptide antagonist. Underpinned by structural homology models of MC4R complexes simulating a presumably active-state conformation compared to the structure of the inactive state, we here briefly summarize the current understanding and key players involved in the MC4R switching process between different activity states. Finally, these perspectives highlight the complexity and plasticity in MC4R signaling regulation and identify gaps in our current knowledge.
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Kühnen P, Wiegand S, Biebermann H. Pharmacological treatment strategies for patients with monogenic obesity. J Pediatr Endocrinol Metab 2020; 33:/j/jpem.ahead-of-print/jpem-2020-0129/jpem-2020-0129.xml. [PMID: 32619193 DOI: 10.1515/jpem-2020-0129] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 04/04/2020] [Indexed: 12/29/2022]
Abstract
The leptin melanocortin signaling pathway is playing a pivotal role for body weight regulation. Genetic defects within this cascade are leading to severe hyperphagia and early onset obesity. In most cases, due to persistent hyperphagia the affected patients are not able to stabilize body weight for a longer period of time with conservative treatment strategies based on lifestyle interventions. Therefore, it is of importance to implement alternative treatment options for these patients. This review provides an overview about the published pharmacological treatment attempts in respect to monogenic forms of obesity and summarizes recent research progress about the role of MC4R signaling and POMC derivatives for body weight regulation.
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Affiliation(s)
- Peter Kühnen
- Institute for Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Berlin Institute of Health, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Susanna Wiegand
- Berlin Institute of Health, Augustenburger Platz 1, 13353 Berlin, Germany
- Center for Social-Pediatric Care, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Heike Biebermann
- Institute for Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Berlin Institute of Health, Augustenburger Platz 1, 13353 Berlin, Germany
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24
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Tao YX. Molecular chaperones and G protein-coupled receptor maturation and pharmacology. Mol Cell Endocrinol 2020; 511:110862. [PMID: 32389798 DOI: 10.1016/j.mce.2020.110862] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 05/04/2020] [Accepted: 05/05/2020] [Indexed: 12/15/2022]
Abstract
G protein-coupled receptors (GPCRs) are highly conserved versatile signaling molecules located at the plasma membrane that respond to diverse extracellular signals. They regulate almost all physiological processes in the vertebrates. About 35% of current drugs target these receptors. Mutations in these genes have been identified as causes of numerous diseases. The seven transmembrane domain structure of GPCRs implies that the folding of these transmembrane proteins is extremely complicated and difficult. Indeed, many wild type GPCRs are not folded optimally. The most common defect in genetic diseases caused by GPCR mutations is misfolding and failure to reach the plasma membrane where it functions. General molecular chaperones aid the folding of all proteins, including GPCRs, by preventing aggregation, promoting folding and disaggregating small aggregates. Some GPCRs need additional receptor-specific chaperones to assist their folding. Many of these receptor-specific chaperones interact with additional receptors and alter receptor pharmacology, expanding the understanding of these chaperone proteins.
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Affiliation(s)
- Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, 36849-5519, USA.
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25
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Delery EC, Edwards S. Neuropeptide and cytokine regulation of pain in the context of substance use disorders. Neuropharmacology 2020; 174:108153. [PMID: 32470337 DOI: 10.1016/j.neuropharm.2020.108153] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 04/23/2020] [Accepted: 05/18/2020] [Indexed: 12/11/2022]
Abstract
Substance use disorders (SUDs) are frequently accompanied by affective symptoms that promote negative reinforcement mechanisms contributing to SUD maintenance or progression. Despite their widespread use as analgesics, chronic or excessive exposure to alcohol, opioids, and nicotine produces heightened nociceptive sensitivity, termed hyperalgesia. This review focuses on the contributions of neuropeptide (CRF, melanocortin, opioid peptide) and cytokine (IL-1β, TNF-α, chemokine) systems in the development and maintenance of substance-induced hyperalgesia. Few effective therapies exist for either chronic pain or SUD, and the common interaction of these disease states likely complicates their effective treatment. Here we highlight promising new discoveries as well as identify gaps in research that could lead to more effective and even simultaneous treatment of SUDs and co-morbid hyperalgesia symptoms.
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Affiliation(s)
- Elizabeth C Delery
- Department of Physiology and Comprehensive Alcohol-HIV/AIDS Research Center, LSU Health Sciences Center, New Orleans, LA, 70112, USA
| | - Scott Edwards
- Department of Physiology and Comprehensive Alcohol-HIV/AIDS Research Center, LSU Health Sciences Center, New Orleans, LA, 70112, USA.
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26
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Ji LQ, Rao YZ, Zhang Y, Chen R, Tao YX. Regulation of melanocortin-1 receptor pharmacology by melanocortin receptor accessory protein 2 in orange-spotted grouper (Epinephelus coioides). Gen Comp Endocrinol 2020; 285:113291. [PMID: 31568758 DOI: 10.1016/j.ygcen.2019.113291] [Citation(s) in RCA: 8] [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: 08/17/2019] [Revised: 09/25/2019] [Accepted: 09/26/2019] [Indexed: 02/06/2023]
Abstract
Melanocortin-1 receptor (MC1R) has important roles in regulating pigmentation and inflammation. Melanocortin receptor accessory protein 2 (MRAP2) modulates trafficking, ligand binding, and signaling of mammalian melanocortin receptors. However, the effect of MRAP2 on fish MC1R has not been extensively studied. Herein, we cloned the orange-spotted grouper (Epinephelus coioides) mc1r, which had a 972 bp open reading frame encoding a putative protein of 323 amino acids. Grouper mc1r was mainly expressed in the brain, skin, testis, spleen, head kidney, and kidney. EcoMC1R showed high constitutive activities in both Gs-cAMP and ERK1/2 pathways, which could be differentially modulated by grouper MRAP2 (EcoMRAP2). Three agonists, including α-melanocyte-stimulating hormone (MSH), β-MSH, and ACTH, could bind to EcoMC1R and dose-dependently increase intracellular cAMP production. EcoMRAP2 had no effect on the IC50 in binding assay or EC50 in cAMP assay; however, it dose-dependently decreased the cell surface expression and maximal response to the three agonists. EcoMRAP2 increased basal ERK1/2 activation but did not alter α-MSH-stimulated ERK1/2 activation. This study extends the knowledge base of fish MC1R pharmacology and its regulation by MRAP2.
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Affiliation(s)
- Li-Qin Ji
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States; Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| | - Ying-Zhu Rao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States; Institute of Applied Biotechnology, Life Science and Technology School, Lingnan Normal University, Zhanjiang 524048, Guangdong, China
| | - Yong Zhang
- Southern Laboratory of Ocean Science and Engineering (Zhuhai, Guangdong), Guangdong Provincial Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Zhuhai 51900, China
| | - Rong Chen
- Institute of Applied Biotechnology, Life Science and Technology School, Lingnan Normal University, Zhanjiang 524048, Guangdong, 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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27
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Tao M, Ji RL, Huang L, Fan SY, Liu T, Liu SJ, Tao YX. Regulation of Melanocortin-4 Receptor Pharmacology by Two Isoforms of Melanocortin Receptor Accessory Protein 2 in Topmouth Culter ( Culter alburnus). Front Endocrinol (Lausanne) 2020; 11:538. [PMID: 32922362 PMCID: PMC7456811 DOI: 10.3389/fendo.2020.00538] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 07/02/2020] [Indexed: 01/03/2023] Open
Abstract
Melanocortin-4 receptor (MC4R) plays important roles in regulation of multiple physiological processes, and interaction of MC4R and melanocortin receptor accessory protein 2 (MRAP2) is suggested to play pivotal role in energy balance of vertebrates. Topmouth culter (Culter alburnus) is an economically important freshwater fish in China. Herein we cloned culter mc4r, mrap2a, and mrap2b. Culter mc4r consisted of a 981 bp open reading frame encoding a protein of 326 amino acids. qRT-PCR revealed that mc4r, mrap2a, and mrap2b were primarily expressed in the central nervous system. In the periphery, mc4r and mrap2b were expressed more widely in the male, while mrap2a was expressed more widely in the female. Culter MC4R could bind to four peptide agonists and increase intracellular cAMP production dose dependently. Culter MC4R was constitutively active in both cAMP and ERK1/2 pathways, which was differentially regulated by culter MRAP2a and MRAP2b. Culter MRAP2a significantly increased Bmax and decreased agonist-stimulated cAMP, while MRAP2b increased cell surface and total expression but did not affect Bmax and agonist-stimulated cAMP. These results will aid the investigation of the potential physiological processes that MC4R might be involved in topmouth culter.
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Affiliation(s)
- Min Tao
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, China
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
| | - Ren-Lei Ji
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
| | - Lu Huang
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Si-Yu Fan
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Ting Liu
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
| | - Shao-Jun Liu
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, China
- *Correspondence: Shao-Jun Liu
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
- Ya-Xiong Tao
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28
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Link R, Veiksina S, Tahk MJ, Laasfeld T, Paiste P, Kopanchuk S, Rinken A. The constitutive activity of melanocortin-4 receptors in cAMP pathway is allosterically modulated by zinc and copper ions. J Neurochem 2019; 153:346-361. [PMID: 31792980 DOI: 10.1111/jnc.14933] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Revised: 11/06/2019] [Accepted: 11/29/2019] [Indexed: 01/25/2023]
Abstract
Melanocortin-4 receptors (MC4 R) are unique among G-protein-coupled receptors (GPCRs) as they have endogenous ligands that can exhibit inverse agonistic properties in the case of elevated basal activity. It is known that the constitutive activity of GPCRs strongly affects the ligand-dependent physiological responses, but little is known about these regulatory mechanisms. Since several metal ions have been shown to be important modulators of the signal transduction of GPCRs, we hypothesized that metal ions regulate the basal activity of MC4 Rs. Implementation of a fluorescence anisotropy assay and novel redshifted fluorescent peptides enabled kinetic characterization of ligand binding to MC4 R expressed on budded baculoviruses. We show that Ca2+ is required for high-affinity ligand binding, but Zn2+ and Cu2+ in the presence of Ca2+ behave as negative allosteric modulators of ligand binding to MC4 R. FRET-based cAMP biosensor was used to measure the activation of MC4 R stably expressed in CHO-K1 cells. At low micromolar concentrations, Zn2+ caused MC4 R-dependent activation of the cAMP pathway, whereas Cu2+ reduced the activity of MC4 R even below the basal level. These findings indicate that at physiologically relevant concentrations can Zn2+ and Cu2+ function as MC4 R agonists or inverse agonists, respectively. This means that depending on the level of constitutive activity induced by Zn2+ ions, the pharmacological effect of orthosteric ligands of MC4 R can be switched from a partial to an inverse agonist. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. More information about the Open Science badges can be found at https://cos.io/our-services/open-science-badges/.
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Affiliation(s)
- Reet Link
- Institute of Chemistry, University of Tartu, Tartu, Estonia
| | - Santa Veiksina
- Institute of Chemistry, University of Tartu, Tartu, Estonia
| | | | - Tõnis Laasfeld
- Institute of Chemistry, University of Tartu, Tartu, Estonia
| | - Päärn Paiste
- Department of Geology, University of Tartu, Tartu, Estonia
| | | | - Ago Rinken
- Institute of Chemistry, University of Tartu, Tartu, Estonia
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29
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Rao YZ, Chen R, Zhang Y, Tao YX. Orange-spotted grouper melanocortin-4 receptor: Modulation of signaling by MRAP2. Gen Comp Endocrinol 2019; 284:113234. [PMID: 31398355 DOI: 10.1016/j.ygcen.2019.113234] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 07/02/2019] [Accepted: 07/28/2019] [Indexed: 02/06/2023]
Abstract
Melanocortin-4 receptor (MC4R) and melanocortin receptor accessory protein 2 (MRAP2) play important roles in the melanocortin system, and interaction of MC4R and MRAP2 is suggested to play pivotal role in energy balance of vertebrates. Orange-spotted grouper (Epinephelus coioides) is a widely cultured marine fish with high economic value in Asia. To explore potential interaction between grouper MC4R and MRAP2, herein we cloned grouper mc4r and mrap2. Grouper mc4r consisted of a 981 bp ORF encoding a putative protein of 327 amino acids, while the grouper mrap2 consisted of a 696 bp ORF encoding a putative protein of 232 amino acids. Sequence and phylogenetic analysis revealed that the grouper MC4R and MRAP2 were highly homologous at amino acid levels to several teleost MC4Rs and MRAP2s, respectively. qRT-PCR results showed that both mc4r and mrap2 were expressed primarily in the central nervous system. In the periphery, these genes were expressed more widely in male fish. The cloned grouper MC4R was functional, exhibiting high constitutive activity in cAMP pathway, capable of binding to three peptide agonists and increasing intracellular cAMP production dose-dependently. MRAP2 significantly decreased basal and agonist-stimulated cAMP signaling. MRAP2 also increased basal ERK1/2 activation but decreased ligand-induced stimulation when expressed at high levels. These data will facilitate future investigation of these molecules in regulating diverse physiological processes in orange-spotted grouper.
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Affiliation(s)
- Ying-Zhu Rao
- Institute of Applied Biotechnology, Life Science and Technology School, Lingnan Normal University, Zhanjiang 524048, Guangdong, China; Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States
| | - Rong Chen
- Institute of Applied Biotechnology, Life Science and Technology School, Lingnan Normal University, Zhanjiang 524048, Guangdong, China
| | - Yong Zhang
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266373, 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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30
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Anderson EJP, Ghamari-Langroudi M, Cakir I, Litt MJ, Chen V, Reggiardo RE, Millhauser GL, Cone RD. Late onset obesity in mice with targeted deletion of potassium inward rectifier Kir7.1 from cells expressing the melanocortin-4 receptor. J Neuroendocrinol 2019; 31:e12670. [PMID: 30561082 PMCID: PMC6533113 DOI: 10.1111/jne.12670] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 11/21/2018] [Accepted: 12/11/2018] [Indexed: 01/01/2023]
Abstract
Energy stores in fat tissue are determined in part by the activity of hypothalamic neurones expressing the melanocortin-4 receptor (MC4R). Even a partial reduction in MC4R expression levels in mice, rats or humans produces hyperphagia and morbid obesity. Thus, it is of great interest to understand the molecular basis of neuromodulation by the MC4R. The MC4R is a G protein-coupled receptor that signals efficiently through GαS , and this signalling pathway is essential for normal MC4R function in vivo. However, previous data from hypothalamic slice preparations indicated that activation of the MC4R depolarised neurones via G protein-independent regulation of the ion channel Kir7.1. In the present study, we show that deletion of Kcnj13 (ie, the gene encoding Kir7.1) specifically from MC4R neurones produced resistance to melanocortin peptide-induced depolarisation of MC4R paraventricular nucleus neurones in brain slices, resistance to the sustained anorexic effect of exogenously administered melanocortin peptides, late onset obesity, increased linear growth and glucose intolerance. Some MC4R-mediated phenotypes appeared intact, including Agouti-related peptide-induced stimulation of food intake and MC4R-mediated induction of peptide YY release from intestinal L cells. Thus, a subset of the consequences of MC4R signalling in vivo appears to be dependent on expression of the Kir7.1 channel in MC4R cells.
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Affiliation(s)
- E. J. P. Anderson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - M. Ghamari-Langroudi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - I. Cakir
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan
| | - M. J. Litt
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Valerie Chen
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, California
| | - Roman E. Reggiardo
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, California
| | - Glenn L. Millhauser
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, California
| | - R. D. Cone
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan
- Department of Molecular and Integrative Pharmacology, School of Medicine, University of Michigan, Ann Arbor, Michigan
- Correspondence: Roger D. Cone, Life Sciences Institute, 210 Washtenaw Ave., Ann Arbor, MI 48109,
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31
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Wang W, Guo DY, Lin YJ, Tao YX. Melanocortin Regulation of Inflammation. Front Endocrinol (Lausanne) 2019; 10:683. [PMID: 31649620 PMCID: PMC6794349 DOI: 10.3389/fendo.2019.00683] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 09/19/2019] [Indexed: 12/18/2022] Open
Abstract
Adrenocorticotropic hormone (ACTH), and α-, β-, and γ-melanocyte-stimulating hormones (α-, β-, γ-MSH), collectively known as melanocortins, together with their receptors (melanocortin receptors), are components of an ancient modulatory system. The clinical use of ACTH in the treatment of rheumatoid arthritis started in 1949, originally thought that the anti-inflammatory action was through hypothalamus-pituitary-adrenal axis and glucocorticoid-dependent. Subsequent decades have witnessed extensive attempts in unraveling the physiology and pharmacology of the melanocortin system. It is now known that ACTH, together with α-, β-, and γ-MSHs, also possess glucocorticoid-independent anti-inflammatory and immunomodulatory effects by activating the melanocortin receptors expressed in the brain or peripheral immune cells. This review will briefly introduce the melanocortin system and highlight the action of melanocortins in the regulation of immune functions from in vitro, in vivo, preclinical, and clinical studies. The potential therapeutic use of melanocortins are also summarized.
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Affiliation(s)
- Wei Wang
- Department of Clinical Laboratory, Xiamen Huli Guoyu Clinic, Co., Ltd., Xiamen, China
| | - Dong-Yu Guo
- Department of Clinical Laboratory, Xiamen Huli Guoyu Clinic, Co., Ltd., Xiamen, China
- *Correspondence: Dong-Yu Guo
| | - Yue-Jun Lin
- Department of Clinical Laboratory, Xiamen Huli Guoyu Clinic, Co., Ltd., Xiamen, China
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology, and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
- Ya-Xiong Tao
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32
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Zhang KQ, Hou ZS, Wen HS, Li Y, Qi X, Li WJ, Tao YX. Melanocortin-4 Receptor in Spotted Sea Bass, Lateolabrax maculatus: Cloning, Tissue Distribution, Physiology, and Pharmacology. Front Endocrinol (Lausanne) 2019; 10:705. [PMID: 31681175 PMCID: PMC6813543 DOI: 10.3389/fendo.2019.00705] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 09/30/2019] [Indexed: 01/27/2023] Open
Abstract
Melanocortin-4 receptor (MC4R) plays important roles in regulation of multiple physiological processes including energy homeostasis, reproduction, sexual function, and other functions in mammals. Recent studies suggested that teleost MC4Rs have different physiological functions and pharmacological characteristics when compared to mammalian MC4Rs. In this study, we investigated spotted sea bass (Lateolabrax maculatus) MC4R (LmMC4R) physiology and pharmacology. Spotted sea bass mc4r consisted of a 984 bp open reading frame encoding a protein of 327 amino acids. LmMC4R was homologous to those of several teleost MC4Rs and human MC4R (hMC4R). qRT-PCR and in situ hybridization revealed that mc4r transcripts were highly expressed in the brain, followed by pituitary and liver. Brain mc4r transcripts were down-regulated in long-term and short-term fasting challenges. LmMC4R was a functional receptor with lower maximal binding and higher basal activity than hMC4R. THIQ was not able to displace 125I-NDP-MSH but could affect intracellular cAMP accumulation, suggesting that it was an allosteric ligand for LmMC4R. In vitro studies with spotted sea bass brain cells indicated that mRNA levels of neuropeptide Y and Agouti-related peptide were down-regulated by α-MSH. In summary, we cloned spotted sea bass MC4R, and showed that it had different pharmacological properties compared to hMC4R, and potentially different functions.
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Affiliation(s)
- Kai-Qiang Zhang
- The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, China
| | - Zhi-Shuai Hou
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
| | - Hai-Shen Wen
- The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, China
| | - Yun Li
- The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, China
- *Correspondence: Yun Li
| | - Xin Qi
- The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, China
| | - Wen-Juan Li
- The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, China
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
- Ya-Xiong Tao
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33
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Herrfurth N, Volckmar AL, Peters T, Kleinau G, Müller A, Cetindag C, Schonnop L, Föcker M, Dempfle A, Wudy SA, Grant SFA, Reinehr T, Cousminer DL, Hebebrand J, Biebermann H, Hinney A. Relevance of polymorphisms in MC4R and BDNF in short normal stature. BMC Pediatr 2018; 18:278. [PMID: 30134862 PMCID: PMC6106737 DOI: 10.1186/s12887-018-1245-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 08/06/2018] [Indexed: 12/13/2022] Open
Abstract
Background Variation in genes of the leptinergic-melanocortinergic system influence both body weight and height. Because short normal stature (SNS) is characterized by reduced body height, delayed maturation and leanness, allelic variation of genes in this pathway are hypothesized to affect this common condition. Methods We analyzed the coding regions of LEP, MC4R, MRAP2 and BDNF in 185 children with SNS (height < 5th percentile) to search for non-synonymous and frameshift variants. For association studies (two-sided χ2-tests) population-based data sets (ExAC, EVS and KORA) were used. Cyclic AMP accumulation, cell surface expression, central expression and MAP kinase activation were assayed in vitro to determine the functional implications of identified variants. Results We detected eleven variants predicted to be protein-altering, four in MC4R, four in BDNF, and three in MRAP2. No variants were found in LEP. In vitro analysis implied reduced function for the MC4R variant p.Met215Ile. Loss-of-function is contrary to expectations based on obesity studies, and thus does not support that this variant is relevant for SNS. The minor SNP alleles at MC4R p.Val103Ile and BDNF p.Val66Met were nominally associated with SNS. Conclusion Taken together, although genes of the leptinergic-melanocortinergic system are important for normal growth, our data do not support the involvement of rare mutations in LEP, MC4R, MRAP2 or BDNF in short normal stature. Electronic supplementary material The online version of this article (10.1186/s12887-018-1245-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Nikolas Herrfurth
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Anna-Lena Volckmar
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Triinu Peters
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Present Address: Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Anne Müller
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Cigdem Cetindag
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Laura Schonnop
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Manuel Föcker
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Astrid Dempfle
- Institute of Medical Informatics and Statistics, Christian-Albrechts University Kiel, Kiel, Germany
| | - Stefan A Wudy
- Division of Pediatric Endocrinology and Diabetology, Center of Child and Adolescent Medicine, Giessen, Germany
| | - Struan F A Grant
- Divisions of Human Genetics and Endocrinology, Children's Hospital of Philadelphia Research Institute, Philadelphia, USA.,Department of Genetics, University of Pennsylvania, Philadelphia, USA
| | - Thomas Reinehr
- Department of Pediatric Endocrinology, Diabetes and Nutrition Medicine, Vestische Hospital for Children and Adolescents Datteln, University of Witten/Herdecke, Datteln, Germany
| | - Diana L Cousminer
- Divisions of Human Genetics and Endocrinology, Children's Hospital of Philadelphia Research Institute, Philadelphia, USA.,Department of Genetics, University of Pennsylvania, Philadelphia, USA
| | - Johannes Hebebrand
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Heike Biebermann
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Anke Hinney
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
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Yi TL, Yang LK, Ruan GL, Yang DQ, Tao YX. Melanocortin-4 receptor in swamp eel (Monopterus albus): Cloning, tissue distribution, and pharmacology. Gene 2018; 678:79-89. [PMID: 30075196 DOI: 10.1016/j.gene.2018.07.056] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 07/14/2018] [Accepted: 07/23/2018] [Indexed: 01/10/2023]
Abstract
Melanocortin-4 receptor (MC4R) plays critical roles in the regulation of various physiological processes, such as energy homeostasis, reproduction and sexual function, cardiovascular function, and other functions in mammals. Although the functions of the MC4R in fish have not been extensively studied, the importance of MC4R in regulation of piscine energy expenditure and sexual functions is emerging. Swamp eel (Monopterus albus) is an economically and evolutionarily important fish widely distributed in tropics and subtropics. We cloned swamp eel mc4r (mamc4r), consisting of a 981 bp open reading frame encoding a protein of 326 amino acids. The sequence of maMC4R was homologous to those of several teleost MC4Rs. Phylogenetic and chromosomal synteny analyses showed that maMC4R was closely related to piscine MC4Rs. qRT-PCR revealed that mc4r transcripts were highly expressed in brain and gonads of swamp eel. The maMC4R was further demonstrated to be a functional receptor by pharmacological studies. Four agonists, α-melanocyte stimulating hormone (α-MSH), β-MSH, [Nle4, D-Phe7]-α-MSH (NDP-MSH), and adrenocorticotropin, could bind to maMC4R and induce intracellular cAMP production dose-dependently. Small molecule agonist THIQ allosterically bound to maMC4R and exerted its effect. Similar to other fish MC4Rs, maMC4R also exhibited significantly increased basal activity compared with that of human MC4R. The high basal activity of maMC4R could be decreased by inverse agonist ML00253764, suggesting that maMC4R was indeed constitutively active. The availability of maMC4R and its pharmacological characteristics will facilitate the investigation of its function in regulating diverse physiological processes in swamp eel.
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Affiliation(s)
- Ti-Lin Yi
- School of Animal Science, Yangtze University, Jingzhou 434020, Hubei, China
| | - Li-Kun Yang
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States
| | - Guo-Liang Ruan
- 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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Central Amygdala Circuits Mediate Hyperalgesia in Alcohol-Dependent Rats. J Neurosci 2018; 38:7761-7773. [PMID: 30054393 DOI: 10.1523/jneurosci.0483-18.2018] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 07/06/2018] [Accepted: 07/21/2018] [Indexed: 01/13/2023] Open
Abstract
Alcohol withdrawal symptoms contribute to excessive alcohol drinking and relapse in alcohol-dependent individuals. Among these symptoms, alcohol withdrawal promotes hyperalgesia, but the neurological underpinnings of this phenomenon are not known. Chronic alcohol exposure alters cell signaling in the central nucleus of the amygdala (CeA), and the CeA is implicated in mediating alcohol dependence-related behaviors. The CeA projects to the periaqueductal gray (PAG), a region critical for descending pain modulation, and may have a role in alcohol withdrawal hyperalgesia. Here, we tested the roles of (1) CeA projections to PAG, (2) CeA melanocortin signaling, and (3) PAG μ-opioid receptor signaling in mediating thermal nociception and alcohol withdrawal hyperalgesia in male Wistar rats. Our results demonstrate that alcohol dependence reduces GABAergic signaling from CeA terminals onto PAG neurons and alters the CeA melanocortin system, that CeA-PAG projections and CeA melanocortin signaling mediate alcohol withdrawal hyperalgesia, and that μ-opioid receptors in PAG filter CeA effects on thermal nociception.SIGNIFICANCE STATEMENT Hyperalgesia is commonly seen in individuals with alcohol use disorder during periods of withdrawal, but the neurological underpinnings behind this phenomenon are not completely understood. Here, we tested whether alcohol dependence exerts its influence on pain modulation via effects on the limbic system. Using behavioral, optogenetic, electrophysiological, and molecular biological approaches, we demonstrate that central nucleus of the amygdala (CeA) projections to periaqueductal gray mediate thermal hyperalgesia in alcohol-dependent and alcohol-naive rats. Using pharmacological approaches, we show that melanocortin receptor-4 signaling in CeA alters alcohol withdrawal hyperalgesia, but this effect is not mediated directly at synaptic inputs onto periaqueductal gray-projecting CeA neurons. Overall, our findings support a role for limbic influence over the descending pain pathway and identify a potential therapeutic target for treating hyperalgesia in individuals with alcohol use disorder .
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Abstract
Neuropeptides are the largest class of intercellular signaling molecules, contributing to a wide variety of physiological processes. Neuropeptide receptors are therapeutic targets for a broad range of drugs, including medications to treat pain, addiction, sleep disorders, and nausea. In addition to >100 peptides with known functions, many peptides have been identified in mammalian brain for which the cognate receptors have not been identified. Similarly, dozens of "orphan" G protein-coupled receptors have been identified in the mammalian genome. While it would seem straightforward to match the orphan peptides and receptors, this is not always easily accomplished. In this review we focus on peptides named PEN and big LEN, which are among the most abundant neuropeptides in mouse brain, and their recently identified receptors: GPR83 and GPR171. These receptors are co-expressed in some brain regions and are able to interact. Because PEN and big LEN are produced from the same precursor protein and co-secreted, the interaction of GPR83 and GPR171 is physiologically relevant. In addition to interactions of these two peptides/receptors, PEN and LEN are co-localized with neuropeptide Y and Agouti-related peptide in neurons that regulate feeding. In this review, using these peptide receptors as an example, we highlight the multiple modes of regulation of receptors and present the emerging view that neuropeptides function combinatorially to generate a network of signaling messages. The complexity of neuropeptides, receptors, and their signaling pathways is important to consider both in the initial deorphanization of peptides and receptors, and in the subsequent development of therapeutic applications.
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Affiliation(s)
- Lloyd D Fricker
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, United States
| | - Lakshmi A Devi
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States.
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37
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Understanding melanocortin-4 receptor control of neuronal circuits: Toward novel therapeutics for obesity syndrome. Pharmacol Res 2018; 129:10-19. [DOI: 10.1016/j.phrs.2018.01.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 01/08/2018] [Accepted: 01/08/2018] [Indexed: 01/25/2023]
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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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39
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Differential homologous desensitization of the human histamine H 3 receptors of 445 and 365 amino acids expressed in CHO-K1 cells. Neurochem Int 2018; 112:114-123. [DOI: 10.1016/j.neuint.2017.11.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 11/14/2017] [Accepted: 11/17/2017] [Indexed: 12/21/2022]
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Melanocortins, Melanocortin Receptors and Multiple Sclerosis. Brain Sci 2017; 7:brainsci7080104. [PMID: 28805746 PMCID: PMC5575624 DOI: 10.3390/brainsci7080104] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 08/07/2017] [Accepted: 08/08/2017] [Indexed: 02/07/2023] Open
Abstract
The melanocortins and their receptors have been extensively investigated for their roles in the hypothalamo-pituitary-adrenal axis, but to a lesser extent in immune cells and in the nervous system outside the hypothalamic axis. This review discusses corticosteroid dependent and independent effects of melanocortins on the peripheral immune system, central nervous system (CNS) effects mediated through neuronal regulation of immune system function, and direct effects on endogenous cells in the CNS. We have focused on the expression and function of melanocortin receptors in oligodendroglia (OL), the myelin producing cells of the CNS, with the goal of identifying new therapeutic approaches to decrease CNS damage in multiple sclerosis as well as to promote repair. It is clear that melanocortin signaling through their receptors in the CNS has potential for neuroprotection and repair in diseases like MS. Effects of melanocortins on the immune system by direct effects on the circulating cells (lymphocytes and monocytes) and by signaling through CNS cells in regions lacking a mature blood brain barrier are clear. However, additional studies are needed to develop highly effective MCR targeted therapies that directly affect endogenous cells of the CNS, particularly OL, their progenitors and neurons.
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Janovick JA, Spicer TP, Bannister TD, Scampavia L, Conn PM. Pharmacoperone rescue of vasopressin 2 receptor mutants reveals unexpected constitutive activity and coupling bias. PLoS One 2017; 12:e0181830. [PMID: 28767678 PMCID: PMC5540481 DOI: 10.1371/journal.pone.0181830] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 07/08/2017] [Indexed: 12/30/2022] Open
Abstract
Pharmacoperones are small molecules that diffuse into cells and rescue misfolded, mistrafficked protein mutants, restoring their function. These substances act with high target specificity, serving as templates to fold (or refold) receptors, enzymes, ion channels or other proteins and enable them to pass the scrutiny of the cellular quality control system ("rescue"). In the present study we demonstrate that a rescued mutant (L83Q) of the vasopressin type 2 receptor (V2R), shows a strong bias for Gs coupling unlike the WT V2 receptor, which couples to both Gs and Gq/11. Failure of the mutant to couple to Gq/11 was not due to a limiting quantity of G-proteins since other Gq/11-coupled receptors (WT V2R, histamine receptor and muscarinic receptor) responded appropriately to their ligands. Transfection with DNA encoding Gq enabled the V2 receptor mutant to couple to this G protein, but only modestly compared with the WT receptor. Fourteen V2R mutant pharmacoperones, of multiple chemical classes, obtained from a high throughput screen of a 660,000 structure library, and one V2R peptidomimetic antagonist rescues L83Q. The rescued mutant shows similar bias with all pharmacoperones identified, suggesting that the bias is intrinsic to the mutant protein's structure, rather than due to the chemical class of the pharmacoperone. In the case of V2R mutant Y128S, rescue with a pharmacoperone revealed constitutive activity, also with bias for Gs, although both IP and cAMP were produced in response to agonist. These results suggest that particular rescued receptor mutants show functional characteristics that differ from the WT receptor; a finding that may be important to consider as pharmacoperones are developed as therapeutic agents.
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Affiliation(s)
- Jo Ann Janovick
- Departments of Internal Medicine and Cell Biology/Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas, United States of America
| | - Timothy P. Spicer
- Lead Identification Division, Translational Research Institute and Department of Molecular Therapeutics, Scripps Research Institute, Jupiter, Florida, United States of America
| | - Thomas D. Bannister
- Department of Chemistry, Scripps Research Institute, Jupiter, Florida, United States of America
| | - Louis Scampavia
- Lead Identification Division, Translational Research Institute and Department of Molecular Therapeutics, Scripps Research Institute, Jupiter, Florida, United States of America
| | - P. Michael Conn
- Departments of Internal Medicine and Cell Biology/Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas, United States of America
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Li L, Yang Z, Zhang YP, He S, Liang XF, Tao YX. Molecular cloning, tissue distribution, and pharmacological characterization of melanocortin-4 receptor in grass carp (Ctenopharyngodon idella). Domest Anim Endocrinol 2017; 59:140-151. [PMID: 28152402 DOI: 10.1016/j.domaniend.2016.11.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 11/05/2016] [Accepted: 11/10/2016] [Indexed: 12/15/2022]
Abstract
Melanocortin-4 receptor (MC4R) plays a pivotal role in the mediation of leptin action on food intake and energy expenditure in mammals. The MC4R has also been identified in several teleosts, and its importance in the regulation of fish energy homeostasis is emerging. We herein reported on the molecular cloning, tissue distribution, and pharmacological characterization of MC4R in grass carp (Ctenopharyngodon idella), an economically and ecologically important fish. We showed that grass carp MC4R (ciMC4R) consisted of a 981 bp open reading frame encoding a protein of 326 amino acids, highly homologous (>95%) to several teleost MC4Rs. Phylogenetic and synteny analysis further indicated ciMC4R was closely related to piscine MC4Rs. Using reverse transcription PCR, we found that mc4r messenger RNA was expressed in the brain as well as various peripheral tissues in grass carp. The pharmacological properties of ciMC4R were investigated using 4 agonists, including α-melanocyte stimulating hormone (α-MSH), β-MSH, [Nle4, D-Phe7]-MSH (NDP-MSH), and adrenocorticotropic hormone (ACTH). We showed that all 4 ligands could bind to ciMC4R and initiate dose-dependent intracellular cyclic adenosine monophosphate (cAMP) accumulation. Grass carp MC4R had the highest affinity for NDP-MSH. Both NDP-MSH and ACTH (1-24) exhibited higher potencies compared to the other 2 endogenous agonists. The ciMC4R was constitutively active, with significantly increased basal cAMP level compared with that of human MC4R (P < 0.01). The availability of ciMC4R and its pharmacologic characteristics provide a basis for future investigation of its functional roles in regulating diverse physiological processes and novel insights into understanding the mechanism of food habit transition in grass carp.
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Affiliation(s)
- L Li
- College of Fisheries, Ministry of Agriculture Key Laboratory of Freshwater Animal Breeding, Huazhong Agricultural University, Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan, Hubei 430070, China
| | - Z Yang
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA
| | - Y-P Zhang
- College of Fisheries, Ministry of Agriculture Key Laboratory of Freshwater Animal Breeding, Huazhong Agricultural University, Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan, Hubei 430070, China
| | - S He
- College of Fisheries, Ministry of Agriculture Key Laboratory of Freshwater Animal Breeding, Huazhong Agricultural University, Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan, Hubei 430070, China
| | - X-F Liang
- College of Fisheries, Ministry of Agriculture Key Laboratory of Freshwater Animal Breeding, Huazhong Agricultural University, Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan, Hubei 430070, China.
| | - Y-X Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA.
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Huang H, Wang W, Tao YX. Pharmacological chaperones for the misfolded melanocortin-4 receptor associated with human obesity. Biochim Biophys Acta Mol Basis Dis 2017; 1863:2496-2507. [PMID: 28284973 DOI: 10.1016/j.bbadis.2017.03.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 02/28/2017] [Accepted: 03/01/2017] [Indexed: 01/01/2023]
Abstract
The melanocortin-4 receptor (MC4R) plays a vital role in regulating energy homeostasis. Mutations in the MC4R cause early-onset severe obesity. The majority of loss of function MC4R mutants are retained intracellularly, many of which are not terminally misfolded and can be stabilized and targeted to the plasma membrane by different chaperones. Some of the mutants might be functional once coaxed to the cell surface. Molecular chaperones and chemical chaperones correct the misfolding of some mutant MC4Rs. However, their therapeutic application is very limited due to their non-specific mechanism of action and, for chemical chaperone, high dosage needed to be effective. Several pharmacological chaperones have been identified for the MC4R and Ipsen 5i and Ipsen 17 are the most potent and efficacious. Here we provide a comprehensive review on how different approaches have been applied to rescue misfolded MC4R mutants. This article is part of a Special Issue entitled: Melanocortin Receptors - edited by Ya-Xiong Tao.
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Affiliation(s)
- Hui Huang
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States
| | - Wei Wang
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States.
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44
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Agosti F, Cordisco Gonzalez S, Martinez Damonte V, Tolosa MJ, Di Siervi N, Schioth HB, Davio C, Perello M, Raingo J. Melanocortin 4 receptor constitutive activity inhibits L-type voltage-gated calcium channels in neurons. Neuroscience 2017; 346:102-112. [PMID: 28093215 DOI: 10.1016/j.neuroscience.2017.01.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 12/16/2016] [Accepted: 01/05/2017] [Indexed: 11/19/2022]
Abstract
The melanocortin 4 receptor (MC4R) is a G protein-coupled receptor (GPCR) that is expressed in several brain nuclei playing a crucial role in the regulation of energy balance controlling the homeostasis of the organism. It displays both agonist-evoked and constitutive activity, and moreover, it can couple to different G proteins. Most of the research on MC4R has been focused on agonist-induced activity, while the molecular and cellular basis of MC4R constitutive activity remains scarcely studied. We have previously shown that neuronal N-type voltage-gated calcium channels (CaV2.2) are inhibited by MC4R agonist-dependent activation, while the CaV subtypes that carry L- and P/Q-type current are not. Here, we tested the hypothesis that MC4R constitutive activity can affect CaV, with focus on the channel subtypes that can control transcriptional activity coupled to depolarization (L-type, CaV1.2/1.3) and neurotransmitter release (N- and P/Q-type, CaV2.2 and CaV2.1). We found that MC4R constitutive activity inhibits specifically CaV1.2/1.3 and CaV2.1 subtypes of CaV. We also explored the signaling pathways mediating this inhibition, and thus propose that agonist-dependent and basal MC4R activation modes signal differentially through Gs and Gi/o pathways to impact on different CaV subtypes. In addition, we found that chronic incubation with MC4R endogenous inverse agonist, agouti and agouti-related peptide (AgRP), occludes CaV inhibition in a cell line and in amygdaloid complex cultured neurons as well. Thus, we define new mechanisms of control of the main mediators of depolarization-induced calcium entry into neurons by a GPCR that displays constitutive activity.
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Affiliation(s)
- F Agosti
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE) Universidad de La Plata-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comision de Investigaciones de la Provincia de buenos Aires (CIC), La Plata, Buenos Aires, Argentina
| | - S Cordisco Gonzalez
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE) Universidad de La Plata-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comision de Investigaciones de la Provincia de buenos Aires (CIC), La Plata, Buenos Aires, Argentina
| | - V Martinez Damonte
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE) Universidad de La Plata-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comision de Investigaciones de la Provincia de buenos Aires (CIC), La Plata, Buenos Aires, Argentina
| | - M J Tolosa
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE) Universidad de La Plata-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comision de Investigaciones de la Provincia de buenos Aires (CIC), La Plata, Buenos Aires, Argentina
| | - N Di Siervi
- Instituto de Investigaciones Farmacológicas, ININFA, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, Buenos Aires, Argentina
| | - H B Schioth
- Department of Neuroscience, Functional Pharmacology, Uppsala University, Uppsala, Sweden
| | - C Davio
- Instituto de Investigaciones Farmacológicas, ININFA, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, Buenos Aires, Argentina
| | - M Perello
- Neurophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE) Universidad de La Plata-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comision de Investigaciones de la Provincia de buenos Aires (CIC), La Plata, Buenos Aires, Argentina
| | - J Raingo
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE) Universidad de La Plata-Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comision de Investigaciones de la Provincia de buenos Aires (CIC), La Plata, Buenos Aires, Argentina
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Xiong Q, Chai J, Chen M, Tao YX. Identification and pharmacological analyses of eight naturally occurring caprine melanocortin-1 receptor mutations in three different goat breeds. Gen Comp Endocrinol 2016; 235:1-10. [PMID: 27229376 DOI: 10.1016/j.ygcen.2016.05.023] [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: 05/05/2016] [Revised: 05/19/2016] [Accepted: 05/20/2016] [Indexed: 12/22/2022]
Abstract
The melanocortin-1 receptor (MC1R) belongs to the family of seven transmembrane G protein-coupled receptors and plays a central role in animal coat color. We have sequenced the full coding region of 954bp of the MC1R gene in 72 goats of three breeds with different coat colors and identified five missense mutations (K226E, F250V, G255D, V265I, and C267W) and one silent mutation (A61A), among which two haplotypes with complete linkage disequilibrium (A61A and F250V, G255D and V265I) were found. We performed detailed functional studies on the six single and two double mutations in transiently transfected HEK293T cells. We found that none of the mutants had decreased cell surface expression. However, all the mutants except A61A had decreased constitutive activities in the cAMP pathway. Five mutations (F250V, G255D, G267W, A61A/F250V, G255D/V265I) exhibited significant defects in ligand binding and consequent agonist-induced cAMP signaling and ERK1/2 activation. Additionally, K226E, with normal ligand binding affinity and cAMP signaling, showed a significant defect in ERK1/2 activation, exhibiting biased signaling. Co-expression studies showed that the five defective mutants did not affect wild-type MC1R signaling, hence they were not dominant negative. In summary, we provided detailed data of these goat MC1R mutations leading to a better understanding of the role of MC1R mutation and coat color in goats.
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Affiliation(s)
- Qi Xiong
- Hubei Key Laboratory of Animal Embryo Engineering and Molecular Breeding, Institute of Animal Husbandry and Veterinary Medicine, Hubei Academy of Agricultural Sciences, Wuhan, Hubei 430070, China; Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849-5519, United States
| | - Jin Chai
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849-5519, United States; Ministry of Agriculture Key Laboratory of Swine Breeding and Genetics & Key Laboratory of Agricultural Animal Genetics, Breeding, and Reproduction of Ministry of Education, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Mingxin Chen
- Hubei Key Laboratory of Animal Embryo Engineering and Molecular Breeding, Institute of Animal Husbandry and Veterinary Medicine, Hubei Academy of Agricultural Sciences, Wuhan, Hubei 430070, China
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849-5519, United States.
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Yang Z, Tao YX. Biased signaling initiated by agouti-related peptide through human melanocortin-3 and -4 receptors. Biochim Biophys Acta Mol Basis Dis 2016; 1862:1485-94. [PMID: 27208795 DOI: 10.1016/j.bbadis.2016.05.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Revised: 05/09/2016] [Accepted: 05/16/2016] [Indexed: 01/01/2023]
Abstract
The neural melanocortin receptors (MCRs), melanocortin-3 and -4 receptors (MC3R and MC4R), have been increasingly recognized as important regulators of energy homeostasis. The orexigenic agouti-related peptide (AgRP), initially identified as an endogenous antagonist for both neural MCRs, has been suggested to be a biased agonist of MC4R independent of its antagonizing effects. In the present study, we sought to determine the potential of AgRP to regulate the activation of intracellular kinases, including extracellular signal-regulated kinase 1 and 2 (ERK1/2), AKT and AMP-activated protein kinase (AMPK), through neural MCRs. We showed that AgRP acted as a biased agonist in human MC3R (hMC3R), decreasing cAMP activity of constitutively active mutant (F347A) hMC3R but stimulating ERK1/2 activation in both wide type and F347A hMC3Rs. AgRP-stimulated ERK1/2 phosphorylation through MC3R was abolished by protein kinase A (PKA) inhibitor H-89 but not Rp-cAMPS, whereas AgRP-initiated ERK1/2 activation through MC4R was inhibited by phosphatidylinositol 3-kinase (PI3K) inhibitors wortmannin and LY294002. Both NDP-MSH and AgRP treatment induced significant AKT phosphorylation in GT1-7 cells but not in MC3R- or MC4R-transfected HEK293T cells. The phosphorylated AMPK levels in both GT1-7 cells and HERK293T cells transfected with neural MCRs were significantly decreased upon stimulation with NDP-MSH but not with AgRP. In summary, we provided novel data for AgRP-initiated multiple intracellular signaling pathways, demonstrating biased agonism of AgRP in both neural MCRs, leading to a better understanding of neural MCR pharmacology.
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MESH Headings
- AMP-Activated Protein Kinases/metabolism
- Agouti-Related Protein/metabolism
- Amino Acid Substitution
- Central Nervous System/metabolism
- Cyclic AMP/metabolism
- HEK293 Cells
- Humans
- Kinetics
- Ligands
- MAP Kinase Signaling System
- Mutagenesis, Site-Directed
- Peptide Fragments/metabolism
- Proto-Oncogene Proteins c-akt/metabolism
- Receptor, Melanocortin, Type 3/agonists
- Receptor, Melanocortin, Type 3/genetics
- Receptor, Melanocortin, Type 3/metabolism
- Receptor, Melanocortin, Type 4/agonists
- Receptor, Melanocortin, Type 4/genetics
- Receptor, Melanocortin, Type 4/metabolism
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Signal Transduction
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Affiliation(s)
- Zhao Yang
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States.
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Li JT, Yang Z, Chen HP, Zhu CH, Deng SP, Li GL, Tao YX. Molecular cloning, tissue distribution, and pharmacological characterization of melanocortin-4 receptor in spotted scat, Scatophagus argus. Gen Comp Endocrinol 2016; 230-231:143-52. [PMID: 27080551 DOI: 10.1016/j.ygcen.2016.04.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Revised: 03/26/2016] [Accepted: 04/09/2016] [Indexed: 11/22/2022]
Abstract
Melanocortin-4 receptor (MC4R) plays an important role in the regulation of food intake and energy expenditure in mammals. The functions of the MC4R in fish have not been investigated extensively. We herein reported on the cloning, tissue distribution, and pharmacological characterization of spotted scat (Scatophagus argus) MC4R (SAMC4R). It consisted of a 984bp open reading frame predicted to encode a protein of 327 amino acids. Sequence analysis revealed that SAMC4R was highly homologous (>80%) at amino acid levels to several teleost MC4Rs. Phylogenetic analyses showed that SAMC4R was closely related to piscine MC4R. Using RT-PCR, we showed that in addition to brain, pituitary, and gonads, mc4r mRNA was also widely expressed in peripheral tissues of spotted scat in sexually divergent pattern. With human MC4R (hMC4R) as a control, several agonists including α-melanocyte stimulating hormone (α-MSH), [Nle(4), D-Phe(7)]-α-MSH (NDP-MSH), adrenocorticotropic hormone (ACTH) and THIQ (N-[(3R)-1,2,3,4-tetrahydroisoquinolinium3-ylcarbonyl]-(1R)-1-(4-chlorobenzyl)-2-[4-cyclohexyl-4-(1H-1,2,4-triazol-1-ylmethyl)piperidin-1-yl]-2-oxoethylamine), were used to investigate the binding and signaling properties of SAMC4R. The results showed that SAMC4R bound NDP-MSH with the highest affinity followed by ACTH (1-24) and α-MSH. Similar ranking was also found for hMC4R, although SAMC4R had two to five-fold higher affinities for these ligands. THIQ did not displace NDP-MSH from SAMC4R, different from hMC4R. α-MSH, NDP-MSH, and ACTH (1-24) were identified as potent agonists to stimulate cAMP generation followed by THIQ in SAMC4R. The availability of SAMC4R and its pharmacological characteristics will facilitate the investigation of its function in regulating diverse physiological processes in spotted scat.
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Affiliation(s)
- Jian-Tao Li
- Fisheries College, Guangdong Ocean University, Zhanjiang 524088, China; Key Laboratory of Aquaculture in South China Sea for Aquatic Economic Animal of Guangdong Higher Education Institutes, Guangdong Ocean University, Zhanjiang 524088, China
| | - Zhao Yang
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States
| | - Hua-Pu Chen
- Fisheries College, Guangdong Ocean University, Zhanjiang 524088, China; Key Laboratory of Aquaculture in South China Sea for Aquatic Economic Animal of Guangdong Higher Education Institutes, Guangdong Ocean University, Zhanjiang 524088, China
| | - Chun-Hua Zhu
- Fisheries College, Guangdong Ocean University, Zhanjiang 524088, China; Key Laboratory of Aquaculture in South China Sea for Aquatic Economic Animal of Guangdong Higher Education Institutes, Guangdong Ocean University, Zhanjiang 524088, China
| | - Si-Ping Deng
- Fisheries College, Guangdong Ocean University, Zhanjiang 524088, China; Key Laboratory of Aquaculture in South China Sea for Aquatic Economic Animal of Guangdong Higher Education Institutes, Guangdong Ocean University, Zhanjiang 524088, China
| | - Guang-Li Li
- Fisheries College, Guangdong Ocean University, Zhanjiang 524088, China; Key Laboratory of Aquaculture in South China Sea for Aquatic Economic Animal of Guangdong Higher Education Institutes, Guangdong Ocean University, Zhanjiang 524088, 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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Wang ZQ, Wang W, Shi L, Chai JT, Zhang XJ, Tao YX. Molecular cloning and pharmacological characterization of giant panda (Ailuropoda melanoleuca) melanocortin-4 receptor. Gen Comp Endocrinol 2016; 229:32-40. [PMID: 26896843 DOI: 10.1016/j.ygcen.2016.02.016] [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: 01/26/2016] [Revised: 02/13/2016] [Accepted: 02/15/2016] [Indexed: 10/22/2022]
Abstract
The melanocortin-4 receptor (MC4R) is critical in regulating mammalian food intake and energy expenditure. Giant panda (Ailuropoda melanoleuca), famous as the living fossil, is an endangered species endemic to China. We are interested in exploring the functions of the giant panda MC4R (amMC4R) in regulating energy homeostasis and report herein the molecular cloning and pharmacology of the amMC4R. Sequence analysis revealed that amMC4R was highly homologous (>88%) at nucleotide and amino acid sequences to several mammalian MC4Rs. Western blot revealed that the expression construct myc-amMC4R in pcDNA3.1 was successfully constructed and expressed in HEK293T cells. With human MC4R (hMC4R) as a control, pharmacological characteristics of amMC4R were analyzed with binding and signaling assays. Four agonists, including [Nle(4), D-Phe(7)]-α-melanocyte stimulating hormone (NDP-MSH), α- and β-MSH, and a small molecule agonist, THIQ, were used in binding and signaling assays. We showed that amMC4R bound NDP-MSH with the highest affinity followed by THIQ, α-MSH, and β-MSH, with the same ranking order as hMC4R. Treatment of HEK293T cells expressing amMC4R with different concentrations of agonists resulted in dose-dependent increase of intracellular cAMP levels, with similar EC50s for the four agonists. The results suggested that the cloned amMC4R encoded a functional MC4R. The availability of amMC4R and its binding and signaling properties will facilitate the investigation of amMC4R in regulating food intake and energy homeostasis.
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Affiliation(s)
- Zhi-Qiang Wang
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, People's Republic of China.
| | - Wei Wang
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States
| | - Lin Shi
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, People's Republic of China
| | - Ji-Tian Chai
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, People's Republic of China
| | - Xin-Jun Zhang
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, People's Republic of 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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Wang W, Tao YX. Ghrelin Receptor Mutations and Human Obesity. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2016; 140:131-50. [PMID: 27288828 DOI: 10.1016/bs.pmbts.2016.02.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Growth hormone secretagogue receptor (GHSR) was originally identified as an orphan receptor in porcine and rat anterior pituitary membranes. In 1999, GHSR was deorphanized and shown to be a receptor for ghrelin, a peptide hormone secreted from the stomach. Therefore, GHSR is also called ghrelin receptor. In addition to regulating growth hormone secretion, ghrelin receptor regulates various physiological processes, including food intake and energy expenditure, glucose metabolism, cardiovascular functions, gastric acid secretion and motility, and immune function. Several human genetic studies conducted in populations originated from Europe, Africa, South America, and East Asia identified rare mutations and single nucleotide polymorphisms that might be associated with human obesity and short stature. Functional analyses of mutant GHSRs reveal multiple defects, including cell surface expression, ligand binding, and basal and stimulated signaling. With growing understanding in the functionality of naturally occurring GHSR mutations, potential therapeutic strategies including pharmacological chaperones and novel ligands could be used to correct the GHSR mutants.
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Affiliation(s)
- W Wang
- Department of Anatomy, Physiology, and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, Alabama, USA
| | - Y-X Tao
- Department of Anatomy, Physiology, and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, Alabama, USA.
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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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