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Jobe A, Vijayan R. Orphan G protein-coupled receptors: the ongoing search for a home. Front Pharmacol 2024; 15:1349097. [PMID: 38495099 PMCID: PMC10941346 DOI: 10.3389/fphar.2024.1349097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 02/15/2024] [Indexed: 03/19/2024] Open
Abstract
G protein-coupled receptors (GPCRs) make up the largest receptor superfamily, accounting for 4% of protein-coding genes. Despite the prevalence of such transmembrane receptors, a significant number remain orphans, lacking identified endogenous ligands. Since their conception, the reverse pharmacology approach has been used to characterize such receptors. However, the multifaceted and nuanced nature of GPCR signaling poses a great challenge to their pharmacological elucidation. Considering their therapeutic relevance, the search for native orphan GPCR ligands continues. Despite limited structural input in terms of 3D crystallized structures, with advances in machine-learning approaches, there has been great progress with respect to accurate ligand prediction. Though such an approach proves valuable given that ligand scarcity is the greatest hurdle to orphan GPCR deorphanization, the future pairings of the remaining orphan GPCRs may not necessarily take a one-size-fits-all approach but should be more comprehensive in accounting for numerous nuanced possibilities to cover the full spectrum of GPCR signaling.
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Affiliation(s)
- Amie Jobe
- Department of Biology, College of Science, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Ranjit Vijayan
- Department of Biology, College of Science, United Arab Emirates University, Al Ain, United Arab Emirates
- The Big Data Analytics Center, United Arab Emirates University, Al Ain, United Arab Emirates
- Zayed Bin Sultan Center for Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
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2
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Liu R, Friedrich M, Hemmen K, Jansen K, Adolfi MC, Schartl M, Heinze KG. Dimerization of melanocortin 4 receptor controls puberty onset and body size polymorphism. Front Endocrinol (Lausanne) 2023; 14:1267590. [PMID: 38027153 PMCID: PMC10667928 DOI: 10.3389/fendo.2023.1267590] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 10/24/2023] [Indexed: 12/01/2023] Open
Abstract
Xiphophorus fish exhibit a clear phenotypic polymorphism in puberty onset and reproductive strategies of males. In X. nigrensis and X. multilineatus, puberty onset is genetically determined and linked to a melanocortin 4 receptor (Mc4r) polymorphism of wild-type and mutant alleles on the sex chromosomes. We hypothesized that Mc4r mutant alleles act on wild-type alleles by a dominant negative effect through receptor dimerization, leading to differential intracellular signaling and effector gene activation. Depending on signaling strength, the onset of puberty either occurs early or is delayed. Here, we show by Förster Resonance Energy Transfer (FRET) that wild-type Xiphophorus Mc4r monomers can form homodimers, but also heterodimers with mutant receptors resulting in compromised signaling which explains the reduced Mc4r signaling in large males. Thus, hetero- vs. homo- dimerization seems to be the key molecular mechanism for the polymorphism in puberty onset and body size in male fish.
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Affiliation(s)
- Ruiqi Liu
- Molecular Microscopy, Rudolf Virchow Center for Integrative and Translation Bioimaging, Julius-Maximilians-Universität Würzburg (JMU), Wuerzburg, Germany
- Developmental Biochemistry, Biocenter, Julius-Maximilians-Universität Würzburg (JMU), Wuerzburg, Germany
| | - Mike Friedrich
- Molecular Microscopy, Rudolf Virchow Center for Integrative and Translation Bioimaging, Julius-Maximilians-Universität Würzburg (JMU), Wuerzburg, Germany
| | - Katherina Hemmen
- Molecular Microscopy, Rudolf Virchow Center for Integrative and Translation Bioimaging, Julius-Maximilians-Universität Würzburg (JMU), Wuerzburg, Germany
| | - Kerstin Jansen
- Molecular Microscopy, Rudolf Virchow Center for Integrative and Translation Bioimaging, Julius-Maximilians-Universität Würzburg (JMU), Wuerzburg, Germany
| | - Mateus C. Adolfi
- Developmental Biochemistry, Biocenter, Julius-Maximilians-Universität Würzburg (JMU), Wuerzburg, Germany
| | - Manfred Schartl
- Developmental Biochemistry, Biocenter, Julius-Maximilians-Universität Würzburg (JMU), Wuerzburg, Germany
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX, United States
| | - Katrin G. Heinze
- Molecular Microscopy, Rudolf Virchow Center for Integrative and Translation Bioimaging, Julius-Maximilians-Universität Würzburg (JMU), Wuerzburg, Germany
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3
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Llinas del Torrent C, Raïch I, Gonzalez A, Casajuana-Martin N, Lillo J, Rebassa JB, Ferreiro-Vera C, Sánchez de Medina V, Franco R, Navarro G, Pardo L. The Leu/Val 6.51 Side Chain of Cannabinoid Receptors Regulates the Binding Mode of the Alkyl Chain of Δ 9-Tetrahydrocannabinol. J Chem Inf Model 2023; 63:5927-5935. [PMID: 37644761 PMCID: PMC10523433 DOI: 10.1021/acs.jcim.3c01054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Indexed: 08/31/2023]
Abstract
(-)-Δ9-trans-tetrahydrocannabinol (THC), which is the principal psychoactive constituent of Cannabis, mediates its action by binding to two members of the G-protein-coupled receptor (GPCR) family: the cannabinoid CB1 (CB1R) and CB2 (CB2R) receptors. Molecular dynamics simulations showed that the pentyl chain of THC could adopts an I-shape conformation, filling an intracellular cavity between Phe3.36 and Trp6.48 for initial agonist-induced receptor activation, in CB1R but not in CB2R. This cavity opens to the five-carbon chain of THC by the conformational change of the γ-branched, flexible, Leu6.51 side chain of CB1R, which is not feasible by the β-branched, mode rigid, Val6.51 side chain of CB2R. In agreement with our computational results, THC could not decrease the forskolin-induced cAMP levels in cells expressing mutant CB1RL6.51V receptor but could activate the mutant CB2RV6.51L receptor as efficiently as wild-type CB1R. Additionally, JWH-133, a full CB2R agonist, contains a branched dimethyl moiety in the ligand chain that bridges Phe3.36 and Val6.51 for receptor activation. In this case, the substitution of Val6.51 to Leu in CB2R makes JWH-133 unable to activate CB2RV6.51L. In conclusion, our combined computational and experimental results have shown that the amino acid at position 6.51 is a key additional player in the initial mechanism of activation of GPCRs that recognize signaling molecules derived from lipid species.
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Affiliation(s)
- Claudia Llinas del Torrent
- Laboratory
of Computational Medicine, Biostatistics Unit, Faculty of Medicine, Universitat Autònoma Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Iu Raïch
- Department
of Biochemistry and Molecular Biomedicine, School of Biology, University of Barcelona, 08028 Barcelona, Spain
- Centro
de Investigación en Red, Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, 28031 Madrid, Spain
| | - Angel Gonzalez
- Laboratory
of Computational Medicine, Biostatistics Unit, Faculty of Medicine, Universitat Autònoma Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Nil Casajuana-Martin
- Laboratory
of Computational Medicine, Biostatistics Unit, Faculty of Medicine, Universitat Autònoma Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Jaume Lillo
- Department
of Biochemistry and Physiology, Faculty of Pharmacy and Food Sciences, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Joan Biel Rebassa
- Department
of Biochemistry and Physiology, Faculty of Pharmacy and Food Sciences, Universitat de Barcelona, 08028 Barcelona, Spain
| | | | | | - Rafael Franco
- Department
of Biochemistry and Molecular Biomedicine, School of Biology, University of Barcelona, 08028 Barcelona, Spain
- Centro
de Investigación en Red, Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, 28031 Madrid, Spain
| | - Gemma Navarro
- Centro
de Investigación en Red, Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, 28031 Madrid, Spain
- Department
of Biochemistry and Physiology, Faculty of Pharmacy and Food Sciences, Universitat de Barcelona, 08028 Barcelona, Spain
- Institute
of Neuroscience, University of Barcelona
(NeuroUB), Av Joan XXIII
27-31, 08028 Barcelona, Spain
| | - Leonardo Pardo
- Laboratory
of Computational Medicine, Biostatistics Unit, Faculty of Medicine, Universitat Autònoma Barcelona, 08193 Bellaterra, Barcelona, Spain
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4
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Maggio R, Fasciani I, Petragnano F, Coppolino MF, Scarselli M, Rossi M. Unraveling the Functional Significance of Unstructured Regions in G Protein-Coupled Receptors. Biomolecules 2023; 13:1431. [PMID: 37892113 PMCID: PMC10604838 DOI: 10.3390/biom13101431] [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: 08/30/2023] [Revised: 09/19/2023] [Accepted: 09/20/2023] [Indexed: 10/29/2023] Open
Abstract
Unstructured regions in functional proteins have gained attention in recent years due to advancements in informatics tools and biophysical methods. G protein-coupled receptors (GPCRs), a large family of cell surface receptors, contain unstructured regions in the form of the i3 loop and C-terminus. This review provides an overview of the functional significance of these regions in GPCRs. GPCRs transmit signals from the extracellular environment to the cell interior, regulating various physiological processes. The i3 loop, located between the fifth and sixth transmembrane helices, and the C-terminus, connected to the seventh transmembrane helix, are determinant of interactions with G proteins and with other intracellular partners such as arrestins. Recent studies demonstrate that the i3 loop and C-terminus play critical roles in allosterically regulating GPCR activation. They can act as autoregulators, adopting conformations that, by restricting G protein access, modulate receptor coupling specificity. The length and unstructured nature of the i3 loop and C-terminus provide unique advantages in GPCR interactions with intracellular protein partners. They act as "fishing lines", expanding the radius of interaction and enabling GPCRs to tether scaffolding proteins, thus facilitating receptor stability during cell membrane movements. Additionally, the i3 loop may be involved in domain swapping between GPCRs, generating novel receptor dimers with distinct binding and coupling characteristics. Overall, the i3 loop and C-terminus are now widely recognized as crucial elements in GPCR function and regulation. Understanding their functional roles enhances our comprehension of GPCR structure and signaling complexity and holds promise for advancements in receptor pharmacology and drug development.
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Affiliation(s)
- Roberto Maggio
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy; (I.F.); (F.P.); (M.R.)
| | - Irene Fasciani
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy; (I.F.); (F.P.); (M.R.)
| | - Francesco Petragnano
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy; (I.F.); (F.P.); (M.R.)
| | - Maria Francesca Coppolino
- Department of Life, Health and Environmental Sciences, University of L’Aquila, 67100 L’Aquila, Italy;
| | - Marco Scarselli
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy;
| | - Mario Rossi
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy; (I.F.); (F.P.); (M.R.)
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5
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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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6
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Bernard A, Ojeda Naharros I, Yue X, Mifsud F, Blake A, Bourgain-Guglielmetti F, Ciprin J, Zhang S, McDaid E, Kim K, Nachury MV, Reiter JF, Vaisse C. MRAP2 regulates energy homeostasis by promoting primary cilia localization of MC4R. JCI Insight 2023; 8:e155900. [PMID: 36692018 PMCID: PMC9977312 DOI: 10.1172/jci.insight.155900] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 11/30/2022] [Indexed: 01/24/2023] Open
Abstract
The G protein-coupled receptor melanocortin-4 receptor (MC4R) and its associated protein melanocortin receptor-associated protein 2 (MRAP2) are essential for the regulation of food intake and body weight in humans. MC4R localizes and functions at the neuronal primary cilium, a microtubule-based organelle that senses and relays extracellular signals. Here, we demonstrate that MRAP2 is critical for the weight-regulating function of MC4R neurons and the ciliary localization of MC4R. More generally, our study also reveals that GPCR localization to primary cilia can require specific accessory proteins that may not be present in heterologous cell culture systems. Our findings further demonstrate that targeting of MC4R to neuronal primary cilia is essential for the control of long-term energy homeostasis and suggest that genetic disruption of MC4R ciliary localization may frequently underlie inherited forms of obesity.
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Affiliation(s)
| | | | - Xinyu Yue
- Department of Medicine and The Diabetes Center
| | | | - Abbey Blake
- Department of Medicine and The Diabetes Center
| | | | | | - Sumei Zhang
- Department of Medicine and The Diabetes Center
| | - Erin McDaid
- Department of Medicine and The Diabetes Center
| | - Kellan Kim
- Department of Medicine and The Diabetes Center
| | | | - Jeremy F. Reiter
- Department of Biochemistry and Biophysics, Cardiovascular Research Institute, UCSF, San Francisco, California, USA
- Chan Zuckerberg Biohub, San Francisco, California, USA
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7
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Hinge Region Mediates Signal Transmission of Luteinizing Hormone and Chorionic Gonadotropin Receptor. Comput Struct Biotechnol J 2022; 20:6503-6511. [DOI: 10.1016/j.csbj.2022.11.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 11/19/2022] [Accepted: 11/20/2022] [Indexed: 11/23/2022] Open
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8
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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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9
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Fly casting with ligand sliding and orientational selection supporting complex formation of a GPCR and a middle sized flexible molecule. Sci Rep 2022; 12:13792. [PMID: 35963875 PMCID: PMC9376114 DOI: 10.1038/s41598-022-17920-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 08/02/2022] [Indexed: 11/08/2022] Open
Abstract
A GA-guided multidimensional virtual-system coupled molecular dynamics (GA-mD-VcMD) simulation was conducted to elucidate binding mechanisms of a middle-sized flexible molecule, bosentan, to a GPCR protein, human endothelin receptor type B (hETB). GA-mD-VcMD is a generalized ensemble method that produces a free-energy landscape of the ligand-receptor binding by searching large-scale motions accompanied with stable maintenance of the fragile cell-membrane structure. All molecular components (bosentan, hETB, membrane, and solvent) were represented with an all-atom model. Then sampling was conducted from conformations where bosentan was distant from the binding site in the hETB binding pocket. The deepest basin in the resultant free-energy landscape was assigned to native-like complex conformation. The following binding mechanism was inferred. First, bosentan fluctuating randomly in solution is captured using a tip region of the flexible N-terminal tail of hETB via nonspecific attractive interactions (fly casting). Bosentan then slides occasionally from the tip to the root of the N-terminal tail (ligand–sliding). During this sliding, bosentan passes the gate of the binding pocket from outside to inside of the pocket with an accompanying rapid reduction of the molecular orientational variety of bosentan (orientational selection). Last, in the pocket, ligand–receptor attractive native contacts are formed. Eventually, the native-like complex is completed. The bosentan-captured conformations by the tip-region and root-region of the N-terminal tail correspond to two basins in the free-energy landscape. The ligand-sliding corresponds to overcoming of a free-energy barrier between the basins.
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10
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Abstract
The 5 known melanocortin receptors (MCs) have established physiological roles. With the exception of MC2, these receptors can behave unpredictably, and since they are more widely expressed than their established roles would suggest, it is likely that they have other poorly characterized functions. The aim of this review is to discuss some of the less well-explored aspects of the 4 enigmatic members of this receptor family (MC1,3-5) and describe how these are multifaceted G protein-coupled receptors (GPCRs). These receptors appear to be promiscuous in that they bind several endogenous agonists (products of the proopiomelanocortin [POMC] gene) and antagonists but with inconsistent relative affinities and effects. We propose that this is a result of posttranslational modifications that determine receptor localization within nanodomains. Within each nanodomain there will be a variety of proteins, including ion channels, modifying proteins, and other GPCRs, that can interact with the MCs to alter the availability of receptor at the cell surface as well as the intracellular signaling resulting from receptor activation. Different combinations of interacting proteins and MCs may therefore give rise to the complex and inconsistent functional profiles reported for the MCs. For further progress in understanding this family, improved characterization of tissue-specific functions is required. Current evidence for interactions of these receptors with a range of partners, resulting in modulation of cell signaling, suggests that each should be studied within the full context of their interacting partners. The role of physiological status in determining this context also remains to be characterized.
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Affiliation(s)
- Linda Laiho
- Centre for Discovery Brain Sciences, School of Biomedical Sciences, University of Edinburgh, Edinburgh, UK
| | - Joanne Fiona Murray
- Correspondence: J. F. Murray, PhD, Centre for Discovery Brain Sciences, School of Biomedical Sciences, University of Edinburgh, Hugh Robson Building, 15 George Square, Edinburgh EH8 9DX, UK.
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11
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Piper NBC, Whitfield EA, Stewart GD, Xu X, Furness SGB. Targeting appetite and satiety in diabetes and obesity, via G protein-coupled receptors. Biochem Pharmacol 2022; 202:115115. [PMID: 35671790 DOI: 10.1016/j.bcp.2022.115115] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 05/26/2022] [Accepted: 05/27/2022] [Indexed: 11/17/2022]
Abstract
Type 2 diabetes and obesity have reached pandemic proportions throughout the world, so much so that the World Health Organisation coined the term "Globesity" to help encapsulate the magnitude of the problem. G protein-coupled receptors (GPCRs) are highly tractable drug targets due to their wide involvement in all aspects of physiology and pathophysiology, indeed, GPCRs are the targets of approximately 30% of the currently approved drugs. GPCRs are also broadly involved in key physiologies that underlie type 2 diabetes and obesity including feeding reward, appetite and satiety, regulation of blood glucose levels, energy homeostasis and adipose function. Despite this, only two GPCRs are the target of approved pharmaceuticals for treatment of type 2 diabetes and obesity. In this review we discuss the role of these, and select other candidate GPCRs, involved in various facets of type 2 diabetic or obese pathophysiology, how they might be targeted and the potential reasons why pharmaceuticals against these targets have not progressed to clinical use. Finally, we provide a perspective on the current development pipeline of anti-obesity drugs that target GPCRs.
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Affiliation(s)
- Noah B C Piper
- Receptor Transducer Coupling Laboratory, School of Biomedical Sciences, Faculty of Medicine, University of Queensland, St. Lucia, QLD 4072, Australia
| | - Emily A Whitfield
- Receptor Transducer Coupling Laboratory, School of Biomedical Sciences, Faculty of Medicine, University of Queensland, St. Lucia, QLD 4072, Australia
| | - Gregory D Stewart
- Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences & Department of Pharmacology Monash University, Parkville, VIC 3052, Australia
| | - Xiaomeng Xu
- Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences & Department of Pharmacology Monash University, Parkville, VIC 3052, Australia
| | - Sebastian G B Furness
- Receptor Transducer Coupling Laboratory, School of Biomedical Sciences, Faculty of Medicine, University of Queensland, St. Lucia, QLD 4072, Australia; Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences & Department of Pharmacology Monash University, Parkville, VIC 3052, Australia.
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12
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Fatima MT, Ahmed I, Fakhro KA, Akil ASA. Melanocortin-4 receptor complexity in energy homeostasis,obesity and drug development strategies. Diabetes Obes Metab 2022; 24:583-598. [PMID: 34882941 PMCID: PMC9302617 DOI: 10.1111/dom.14618] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/05/2021] [Accepted: 12/06/2021] [Indexed: 12/19/2022]
Abstract
The melanocortin-4 receptor (MC4R) has been critically investigated for the past two decades, and novel findings regarding MC4R signalling and its potential exploitation in weight loss therapy have lately been emphasized. An association between MC4R and obesity is well established, with disease-causing mutations affecting 1% to 6% of obese patients. More than 200 MC4R variants have been reported, although conflicting results as to their effects have been found in different cohorts. Most notably, some MC4R gain-of-function variants seem to rescue obesity and related complications via specific pathways such as beta-arrestin (ß-arrestin) recruitment. Broadly speaking, however, dysfunctional MC4R dysregulates satiety and induces hyperphagia. The picture at the mechanistic level is complicated as, in addition to the canonical G stimulatory pathway, the ß-arrestin signalling pathway and ions (particularly calcium) seem to interact with MC4R signalling to contribute to or alleviate obesity pathogenesis. Thus, the overall complexity of the MC4R signalling spectra has broadened considerably, indicating there is great potential for the development of new drugs to manage obesity and its related complications. Alpha-melanocyte-stimulating hormone is the major endogenous MC4R agonist, but structure-based ligand discovery studies have identified possible superior and selective agonists that can improve MC4R function. However, some of these agonists characterized in vitro and in vivo confer adverse effects in patients, as demonstrated in clinical trials. In this review, we provide a comprehensive insight into the genetics, function and regulation of MC4R and its contribution to obesity. We also outline new approaches in drug development and emerging drug candidates to treat obesity.
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Affiliation(s)
- Munazza Tamkeen Fatima
- Department of Human Genetics, Translational Medicine DivisionResearch Branch, Sidra MedicineDohaQatar
| | - Ikhlak Ahmed
- Department of Human Genetics, Translational Medicine DivisionResearch Branch, Sidra MedicineDohaQatar
| | - Khalid Adnan Fakhro
- Department of Human Genetics, Translational Medicine DivisionResearch Branch, Sidra MedicineDohaQatar
- Department of Genetic MedicineWeill Cornell MedicineDohaQatar
- College of Health and Life SciencesHamad Bin Khalifa UniversityDohaQatar
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13
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Li Y, Wang X, Lu L, Wang M, Zhai Y, Tai X, Dilimulati D, Lei X, Xu J, Zhang C, Fu Y, Qu S, Li Q, Zhang C. Identification of novel GPCR partners of the central melanocortin signaling. Mol Metab 2021; 53:101317. [PMID: 34400348 PMCID: PMC8458986 DOI: 10.1016/j.molmet.2021.101317] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 08/03/2021] [Accepted: 08/10/2021] [Indexed: 12/12/2022] Open
Abstract
OBJECTIVE Homo- or heterodimerization of G protein-coupled receptors (GPCRs) generally affects the normal functioning of these receptors and mediates the responses to a variety of physiological stimuli in vivo. It is well known that melanocortin-3 receptor (MC3R) and melanocortin-4 receptor (MC4R) are key regulators of appetite and energy homeostasis in the central nervous system. However, the GPCR partners of MC3R and MC4R are not well understood. Our objective is to analyze single cell RNA-seq datasets of the hypothalamus to explore and identify novel GPCR partners of MC3R and MC4R and examine the pharmacological effect on the downstream signal transduction and membrane translocation of melanocortin receptors. METHODS We conducted an integrative analysis of multiple single cell RNA-seq datasets to reveal the expression pattern and correlation of GPCR families in the mouse hypothalamus. The emerging GPCRs with important metabolic functions were selected for cloning and co-immunoprecipitation validation. The positive GPCR partners were then tested for the pharmacological activation, competitive binding assay and surface translocation ELISA experiments. RESULTS Based on the expression pattern of GPCRs and their function enrichment results, we narrowed down the range of potential GPCR interaction with MC3R and MC4R for further confirmation. Co-immunoprecipitation assay verified 23 and 32 novel GPCR partners that interacted with MC3R and MC4R in vitro. The presence of these GPCR partners exhibited different effects in the physiological regulation and signal transduction of MC3R and MC4R. CONCLUSIONS This work represented the first large-scale screen for the functional GPCR complex of central melanocortin receptors and defined a composite metabolic regulatory GPCR network of the hypothalamic nucleuses.
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Affiliation(s)
- Yunpeng Li
- Department of Endocrinology and Metabolism, National Metabolic Management Center, Shanghai Tenth People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Xiaozhu Wang
- Shanghai Key Laboratory of Signaling and Disease Research, Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Shanghai East Hospital, Tongji University, Shanghai, China.
| | - Liumei Lu
- Department of Endocrinology and Metabolism, National Metabolic Management Center, Shanghai Tenth People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, Frontier Science Center for Stem Cell 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
| | - Yue Zhai
- Department of Endocrinology and Metabolism, National Metabolic Management Center, Shanghai Tenth People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Xiaolu Tai
- Department of Endocrinology and Metabolism, National Metabolic Management Center, Shanghai Tenth People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Diliqingna Dilimulati
- Department of Endocrinology and Metabolism, National Metabolic Management Center, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Xiaowei Lei
- Department of Endocrinology and Metabolism, National Metabolic Management Center, Shanghai Tenth People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Jing Xu
- Department of Endocrinology and Metabolism, National Metabolic Management Center, Shanghai Tenth People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, Frontier Science Center for Stem Cell 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, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yanbin Fu
- 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
| | - Shen Qu
- Department of Endocrinology and Metabolism, National Metabolic Management Center, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, China.
| | - Qingfeng 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.
| | - Chao Zhang
- 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.
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14
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Gómez-Melero S, García-Maceira FI, García-Maceira T, Luna-Guerrero V, Montero-Peñalvo G, Túnez-Fiñana I, Paz-Rojas E. Amino terminal recognition by a CCR6 chemokine receptor antibody blocks CCL20 signaling and IL-17 expression via β-arrestin. BMC Biotechnol 2021; 21:41. [PMID: 34225700 PMCID: PMC8259436 DOI: 10.1186/s12896-021-00699-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 05/25/2021] [Indexed: 12/25/2022] Open
Abstract
Background CCR6 chemokine receptor is an important target in inflammatory diseases. Th17 cells express CCR6 and a number of inflammatory cytokines, including IL-17 and IL-22, which are involved in the propagation of inflammatory immune responses. CCR6 antagonist would be a potential treatment for inflammatory diseases such as psoriasis or rheumatoid arthritis. The aim of this study is to develop an antagonistic monoclonal antibody (mAb) against human CCR6 receptor (hCCR6). Results We generate monoclonal antibodies against hCCR6 immunizing Balb/c mice with hCCR6 overexpressing cells. The antibodies were tested by flow cytometry for specific binding to hCCR6, cloned by limiting dilution and resulted in the isolation and purification monoclonal antibody 1C6. By ELISA and flow cytometry, was determined that the antibody obtained binds to hCCR6 N-terminal domain. The ability of 1C6 to neutralize hCCR6 signaling was tested and we determined that 1C6 antibody were able to block response in β-arrestin recruitment assay with IC50 10.23 nM, but did not inhibit calcium mobilization. In addition, we found in a chemotaxis assay that 1C6 reduces the migration of hCCR6 cells to their ligand CCL20. Finally, we determined by RT-qPCR that the expression of IL-17A in Th17 cells treated with 1C6 was inhibited. Conclusions In the present study, we applied whole cell immunization for successfully obtain an antibody that is capable to neutralize hCCR6 signaling and to reduce hCCR6 cells migration and IL-17 expression. These results provide an efficient approach to obtain therapeutic potential antibodies in the treatment of CCR6-mediated inflammatory diseases. Supplementary Information The online version contains supplementary material available at 10.1186/s12896-021-00699-2.
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Affiliation(s)
- Sara Gómez-Melero
- Canvax Biotech, Parque Científico y Tecnológico Rabanales 21, c/Astrónoma Cecilia Payne s/n, Edificio Canvax, 14014, Córdoba, Spain.
| | - Fé Isabel García-Maceira
- Canvax Biotech, Parque Científico y Tecnológico Rabanales 21, c/Astrónoma Cecilia Payne s/n, Edificio Canvax, 14014, Córdoba, Spain
| | - Tania García-Maceira
- Canvax Biotech, Parque Científico y Tecnológico Rabanales 21, c/Astrónoma Cecilia Payne s/n, Edificio Canvax, 14014, Córdoba, Spain
| | - Verónica Luna-Guerrero
- Canvax Biotech, Parque Científico y Tecnológico Rabanales 21, c/Astrónoma Cecilia Payne s/n, Edificio Canvax, 14014, Córdoba, Spain
| | - Gracia Montero-Peñalvo
- Canvax Biotech, Parque Científico y Tecnológico Rabanales 21, c/Astrónoma Cecilia Payne s/n, Edificio Canvax, 14014, Córdoba, Spain
| | - Isaac Túnez-Fiñana
- Department of Biochemistry and Molecular Biology, School of Medicine, University of Córdoba, Avda. Menéndez Pidal s/n, 14004, Córdoba, Spain
| | - Elier Paz-Rojas
- Canvax Biotech, Parque Científico y Tecnológico Rabanales 21, c/Astrónoma Cecilia Payne s/n, Edificio Canvax, 14014, Córdoba, Spain
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15
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Navarro G, Gonzalez A, Sánchez-Morales A, Casajuana-Martin N, Gómez-Ventura M, Cordomí A, Busqué F, Alibés R, Pardo L, Franco R. Design of Negative and Positive Allosteric Modulators of the Cannabinoid CB 2 Receptor Derived from the Natural Product Cannabidiol. J Med Chem 2021; 64:9354-9364. [PMID: 34161090 DOI: 10.1021/acs.jmedchem.1c00561] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Cannabidiol (CBD), the second most abundant of the active compounds found in the Cannabis sativa plant, is of increasing interest because it is approved for human use and is neither euphorizing nor addictive. Here, we design and synthesize novel compounds taking into account that CBD is both a partial agonist, when it binds to the orthosteric site, and a negative allosteric modulator, when it binds to the allosteric site of the cannabinoid CB2 receptor. Molecular dynamic simulations and site-directed mutagenesis studies have identified the allosteric site near the receptor entrance. This knowledge has permitted to perform structure-guided design of negative and positive allosteric modulators of the CB2 receptor with potential therapeutic utility.
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Affiliation(s)
- Gemma Navarro
- Department of Biochemistry and Physiology, Faculty of Pharmacy and Food Sciences, Universitat de Barcelona, 08028 Barcelona, Spain.,Centro de Investigación en Red, Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, 28031 Madrid, Spain
| | - Angel Gonzalez
- Laboratory of Computational Medicine, Biostatistics Unit, Faculty of Medicine, Universitat Autònoma Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Adrià Sánchez-Morales
- Departament de Química, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Nil Casajuana-Martin
- Laboratory of Computational Medicine, Biostatistics Unit, Faculty of Medicine, Universitat Autònoma Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Marc Gómez-Ventura
- Departament de Química, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Arnau Cordomí
- Laboratory of Computational Medicine, Biostatistics Unit, Faculty of Medicine, Universitat Autònoma Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Félix Busqué
- Departament de Química, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Ramon Alibés
- Departament de Química, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Leonardo Pardo
- Laboratory of Computational Medicine, Biostatistics Unit, Faculty of Medicine, Universitat Autònoma Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Rafael Franco
- Centro de Investigación en Red, Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, 28031 Madrid, Spain.,Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Universitat de Barcelona, 08028 Barcelona, Spain
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16
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Wang Y, Bernard A, Comblain F, Yue X, Paillart C, Zhang S, Reiter JF, Vaisse C. Melanocortin 4 receptor signals at the neuronal primary cilium to control food intake and body weight. J Clin Invest 2021; 131:142064. [PMID: 33938449 DOI: 10.1172/jci142064] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 03/18/2021] [Indexed: 01/02/2023] Open
Abstract
The melanocortin 4 receptor (MC4R) plays a critical role in the long-term regulation of energy homeostasis, and mutations in the MC4R are the most common cause of monogenic obesity. However, the precise molecular and cellular mechanisms underlying the maintenance of energy balance within MC4R-expressing neurons are unknown. We recently reported that the MC4R localizes to the primary cilium, a cellular organelle that allows for partitioning of incoming cellular signals, raising the question of whether the MC4R functions in this organelle. Here, using mouse genetic approaches, we found that cilia were required specifically on MC4R-expressing neurons for the control of energy homeostasis. Moreover, these cilia were critical for pharmacological activators of the MC4R to exert an anorexigenic effect. The MC4R is expressed in multiple brain regions. Using targeted deletion of primary cilia, we found that cilia in the paraventricular nucleus of the hypothalamus (PVN) were essential to restrict food intake. MC4R activation increased adenylyl cyclase (AC) activity. As with the removal of cilia, inhibition of AC activity in the cilia of MC4R-expressing neurons of the PVN caused hyperphagia and obesity. Thus, the MC4R signaled via PVN neuron cilia to control food intake and body weight. We propose that defects in ciliary localization of the MC4R cause obesity in human inherited obesity syndromes and ciliopathies.
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Affiliation(s)
- Yi Wang
- Department of Medicine and The Diabetes Center and
| | | | | | - Xinyu Yue
- Department of Medicine and The Diabetes Center and
| | | | - Sumei Zhang
- Department of Medicine and The Diabetes Center and
| | - Jeremy F Reiter
- Department of Biochemistry and Biophysics, Cardiovascular Research Institute, UCSF, San Francisco, California, USA.,Chan Zuckerberg Biohub, San Francisco, California, USA
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17
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The N-terminus of GPR37L1 is proteolytically processed by matrix metalloproteases. Sci Rep 2020; 10:19995. [PMID: 33203955 PMCID: PMC7673139 DOI: 10.1038/s41598-020-76384-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 10/22/2020] [Indexed: 12/11/2022] Open
Abstract
GPR37L1 is an orphan G protein-coupled receptor expressed exclusively in the brain and linked to seizures, neuroprotection and cardiovascular disease. Based upon the observation that fragments of the GPR37L1 N-terminus are found in human cerebrospinal fluid, we hypothesized that GPR37L1 was subject to post-translational modification. Heterologous expression of GPR37L1-eYFP in either HEK293 or U87 glioblastoma cells yielded two cell surface species of approximately equivalent abundance, the larger of which is N-glycosylated at Asn105. The smaller species is produced by matrix metalloprotease/ADAM-mediated proteolysis (shown by the use of pharmacological inhibitors) and has a molecular weight identical to that of a mutant lacking the entire N-terminus, Δ122 GPR37L1. Serial truncation of the N-terminus prevented GPR37L1 expression except when the entire N-terminus was removed, narrowing the predicted site of N-terminal proteolysis to residues 105–122. Using yeast expressing different G protein chimeras, we found that wild type GPR37L1, but not Δ122 GPR37L1, coupled constitutively to Gpa1/Gαs and Gpa1/Gα16 chimeras, in contrast to previous studies. We tested the peptides identified in cerebrospinal fluid as well as their putative newly-generated N-terminal ‘tethered’ counterparts in both wild type and Δ122 GPR37L1 Gpa1/Gαs strains but saw no effect, suggesting that GPR37L1 does not signal in a manner akin to the protease-activated receptor family. We also saw no evidence of receptor activation or regulation by the reported GPR37L1 ligand, prosaptide/TX14A. Finally, the proteolytically processed species predominated both in vivo and ex vivo in organotypic cerebellar slice preparations, suggesting that GPR37L1 is rapidly processed to a signaling-inactive form. Our data indicate that the function of GPR37L1 in vivo is tightly regulated by metalloprotease-dependent N-terminal cleavage.
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18
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Navarro G, Gonzalez A, Campanacci S, Rivas-Santisteban R, Reyes-Resina I, Casajuana-Martin N, Cordomí A, Pardo L, Franco R. Experimental and computational analysis of biased agonism on full-length and a C-terminally truncated adenosine A 2A receptor. Comput Struct Biotechnol J 2020; 18:2723-2732. [PMID: 33101610 PMCID: PMC7550916 DOI: 10.1016/j.csbj.2020.09.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 09/15/2020] [Accepted: 09/16/2020] [Indexed: 12/24/2022] Open
Abstract
Biased agonism, the ability of agonists to differentially activate downstream signaling pathways by stabilizing specific receptor conformations, is a key issue for G protein-coupled receptor (GPCR) signaling. The C-terminal domain might influence this functional selectivity of GPCRs as it engages G proteins, GPCR kinases, β-arrestins, and several other proteins. Thus, the aim of this paper is to compare the agonist-dependent selectivity for intracellular pathways in a heterologous system expressing the full-length (A2AR) and a C-tail truncated (A2AΔ40R lacking the last 40 amino acids) adenosine A2A receptor, a GPCR that is already targeted in Parkinson’s disease using a first-in-class drug. Experimental data such as ligand binding, cAMP production, β-arrestin recruitment, ERK1/2 phosphorylation and dynamic mass redistribution assays, which correspond to different aspects of signal transduction, were measured upon the action of structurally diverse compounds (the agonists adenosine, NECA, CGS-21680, PSB-0777 and LUF-5834 and the SCH-58261 antagonist) in cells expressing A2AR and A2AΔ40R. The results show that taking cAMP levels and the endogenous adenosine agonist as references, the main difference in bias was obtained with PSB-0777 and LUF-5834. The C-terminus is dispensable for both G-protein and β-arrestin recruitment and also for MAPK activation. Unrestrained molecular dynamics simulations, at the μs timescale, were used to understand the structural arrangements of the binding cavity, triggered by these chemically different agonists, facilitating G protein binding with different efficacy.
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Affiliation(s)
- Gemma Navarro
- Dept. Biochemistry and Physiology, Faculty of Pharmacy and Food Science. Universitat de Barcelona. Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas. Instituto de Salud Carlos III, Madrid, Spain
| | - Angel Gonzalez
- Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain d Faculty of Chemistry, Universitat de Barcelona, Barcelona, Spain
| | - Stefano Campanacci
- Dept. Biochemistry and Molecular Biomedicine. School of Biology. Universitat de Barcelona. Barcelona. Spain
| | - Rafael Rivas-Santisteban
- Dept. Biochemistry and Physiology, Faculty of Pharmacy and Food Science. Universitat de Barcelona. Barcelona, Spain
- Dept. Biochemistry and Molecular Biomedicine. School of Biology. Universitat de Barcelona. Barcelona. Spain
| | - Irene Reyes-Resina
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas. Instituto de Salud Carlos III, Madrid, Spain
- Dept. Biochemistry and Molecular Biomedicine. School of Biology. Universitat de Barcelona. Barcelona. Spain
| | - Nil Casajuana-Martin
- Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain d Faculty of Chemistry, Universitat de Barcelona, Barcelona, Spain
| | - Arnau Cordomí
- Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain d Faculty of Chemistry, Universitat de Barcelona, Barcelona, Spain
| | - Leonardo Pardo
- Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain d Faculty of Chemistry, Universitat de Barcelona, Barcelona, Spain
| | - Rafael Franco
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas. Instituto de Salud Carlos III, Madrid, Spain
- School of Chemistry. Universitat de Barcelona. Barcelona. Spain
- Corresponding author at: School of Chemistry, University of Barcelona, Diagonal 643, 08028 Barcelona, Spain.
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19
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Liu R, Du K, Ormanns J, Adolfi MC, Schartl M. Melanocortin 4 receptor signaling and puberty onset regulation in Xiphophorus swordtails. Gen Comp Endocrinol 2020; 295:113521. [PMID: 32470471 DOI: 10.1016/j.ygcen.2020.113521] [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: 02/14/2020] [Revised: 04/15/2020] [Accepted: 05/22/2020] [Indexed: 01/01/2023]
Abstract
Fish of the genus Xiphophorus provide a prominent example of genetic control of male body size and reproductive tactics. In X.nigrensis and X.multilineatus, puberty onset and body length are determined by melanocortin 4 receptor (Mc4r) allelic and copy number variations which were proposed to fine-tune the signaling output of the system. Accessory protein Mrap2 is required for growth across species by affecting Mc4r signaling. The molecular mechanism how Mc4r signaling controls puberty regulation in Xiphophorus and whether the interaction with Mrap2 is also involved was so far unclear. Hence, we examined Mc4r and Mrap2 in X.nigrensis and X.multilineatus, in comparison to a more distantly related species, X.hellerii. mc4r and mrap2 transcripts co-localized in the hypothalamus and preoptic regions in large males, small males and females of X.nigrensis, with similar signal strength for mrap2 but higher expression of mc4r in large males. This overexpression is constituted by wild-type and one subtype of mutant alleles. In vitro studies revealed that Mrap2 co-expressed with Mc4r increased cAMP production but did not change EC50. Cells co-expressing the wild-type and one mutant allele showed lower cAMP signaling than Mc4r wild-type cells. This indicates a role of Mc4r alleles, but not Mrap2, in puberty signaling. Different from X.nigrensis and X.multilineatus, X.hellerii has only wild-type alleles, but also shows a puberty onset and body length polymorphism, despite the absence of mutant alleles. Like in the two other species, mc4r and mrap2 transcripts colocalized and mc4r is expressed at substantially higher levels in large males. This demonstrates that puberty and growth regulation mechanism may not be identical even within same genus.
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MESH Headings
- Adaptor Proteins, Signal Transducing/metabolism
- Alleles
- Amino Acid Sequence
- Animals
- Cyprinodontiformes/genetics
- Cyprinodontiformes/metabolism
- DNA Copy Number Variations/genetics
- Female
- Gene Expression Regulation, Developmental
- Male
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptor, Melanocortin, Type 4/chemistry
- Receptor, Melanocortin, Type 4/genetics
- Receptor, Melanocortin, Type 4/metabolism
- Sexual Maturation/physiology
- Signal Transduction
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Affiliation(s)
- Ruiqi Liu
- Physiological Chemistry, Biocenter, University of Wuerzburg, Wuerzburg, Germany
| | - Kang Du
- Physiological Chemistry, Biocenter, University of Wuerzburg, Wuerzburg, Germany; Developmental Biochemistry, Biocenter, University of Wuerzburg, Wuerzburg, Germany
| | - Jenny Ormanns
- Physiological Chemistry, Biocenter, University of Wuerzburg, Wuerzburg, Germany
| | - Mateus C Adolfi
- Physiological Chemistry, Biocenter, University of Wuerzburg, Wuerzburg, Germany; Developmental Biochemistry, Biocenter, University of Wuerzburg, Wuerzburg, Germany
| | - Manfred Schartl
- Physiological Chemistry, Biocenter, University of Wuerzburg, Wuerzburg, Germany; Developmental Biochemistry, Biocenter, University of Wuerzburg, Wuerzburg, Germany; The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX, USA.
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20
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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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21
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Zachmann J, Kritsi E, Tapeinou A, Zoumpoulakis P, Tselios T, Matsoukas MT. Combined Computational and Structural Approach into Understanding the Role of Peptide Binding and Activation of Melanocortin Receptor 4. J Chem Inf Model 2020; 60:1461-1468. [PMID: 31944109 DOI: 10.1021/acs.jcim.9b01196] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Melanocortin receptor 4 (MC4R) is expressed predominantly in the central nervous system and regulates food intake and sexual function and is also thought to be responsible for effects on mood and cognition. It belongs to the melanocortin receptor subfamily of G protein-coupled receptors (GPCRs). Here, we have synthesized and structurally characterized three peptides that bind to MC4R, producing different signaling events. AgRP is a naturally occurring antagonist, HLWNRS is the minimal sequence of the N-terminal with partial agonist activity, and aMSH is a full agonistic peptide. By implementing molecular dynamics simulations on the different peptide-receptor complexes, we propose their molecular basis of binding to investigate their differential molecular properties regarding the activation states of the receptor. Our analysis shows that the agonist and partial agonist may induce rotation in transmembrane helix 3, which is known to be involved in the key events occurring during GPCR activation, and this movement is impacted by certain aromatic residues and their positioning in the orthosteric binding site of the receptor.
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Affiliation(s)
- Julian Zachmann
- Department of Biostatistics, Autonomous University of Barcelona, 08193 Bellaterra, Spain
| | - Eftichia Kritsi
- Institute of Chemical Biology, National Hellenic Research Foundation, 11635 Athens, Greece
| | - Anthi Tapeinou
- Department of Chemistry, University of Patras, 26500 Patras, Greece
| | | | - Theodore Tselios
- Department of Chemistry, University of Patras, 26500 Patras, Greece
| | - Minos-Timotheos Matsoukas
- Department of Pharmacy, University of Patras, 26500 Patras, Greece.,Department of Biostatistics, Autonomous University of Barcelona, 08193 Bellaterra, Spain
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22
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Falls BA, Zhang Y. Insights into the Allosteric Mechanism of Setmelanotide (RM-493) as a Potent and First-in-Class Melanocortin-4 Receptor (MC4R) Agonist To Treat Rare Genetic Disorders of Obesity through an in Silico Approach. ACS Chem Neurosci 2019; 10:1055-1065. [PMID: 30048591 DOI: 10.1021/acschemneuro.8b00346] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Human melanocortin-4 receptor (hMC4R) mutations have been implicated as the cause for about 6-8% of all severe obesity cases. Drug-like molecules that are able to rescue the functional activity of mutated receptors are highly desirable to combat genetic obesity among this population of patients. One such molecule is the selective MC4R agonist RM-493 (setmelanotide). While this molecule has been shown to activate mutated receptors with 20-fold higher potency over the endogenous agonist, little is known about its binding mode and how it effectively interacts with hMC4R despite the presence of mutations. In this study, a MC4R homology model was constructed based on the X-ray crystal structure of the adenosine A2A receptor in the active state. Four MC4R mutations commonly found in genetically obese patients and known to effect ligand binding in vitro were introduced into the constructed model. RM-493 was then docked into the wild-type and mutated models in order to better elucidate the possible binding modes for this promising drug candidate and assess how it may be interacting with MC4R to effectively activate receptor polymorphisms. The results reflected the orthosteric interactions of both the endogenous and synthetic ligands with the MC4R, which is supported by the site-directed mutagenesis studies. Meanwhile it helped explain the decremental affinity and potency of these ligands with the receptor polymorphisms. More significantly, our findings indicated that the structural characteristics of RM-493 may allow for enhanced receptor-ligand interactions, particularly through those with the putative allosteric binding sites, which facilitated the ligand to stabilize the active state of native and mutant MC4Rs to maintain reasonably high affinity and potency.
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Affiliation(s)
- Bethany A. Falls
- Department of Medicinal Chemistry, Virginia Commonwealth University, 800 East Leigh Street, Richmond, Virginia 23298, United States
| | - Yan Zhang
- Department of Medicinal Chemistry, Virginia Commonwealth University, 800 East Leigh Street, Richmond, Virginia 23298, United States
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23
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Oakes V, Domene C. Influence of Cholesterol and Its Stereoisomers on Members of the Serotonin Receptor Family. J Mol Biol 2019; 431:1633-1649. [PMID: 30857969 DOI: 10.1016/j.jmb.2019.02.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 02/27/2019] [Accepted: 02/28/2019] [Indexed: 01/24/2023]
Abstract
Despite the ubiquity of cholesterol within the cell membrane, the mechanism by which it influences embedded proteins remains elusive. Numerous G-protein coupled receptors exhibit dramatic responses to membrane cholesterol with regard to the ligand-binding affinity and functional properties, including the 5-HT receptor family. Here, we use over 25 μs of unbiased atomistic molecular dynamics simulations to identify cholesterol interaction sites in the 5-HT1B and 5-HT2B receptors and evaluate their impact on receptor structure. Susceptibility to membrane cholesterol is shown to be subtype dependent and determined by the quality of interactions between the extracellular loops. Charged residues are essential for maintaining the arrangement of the extracellular surface in 5-HT2B; in the absence of such interactions, the extracellular surface of the 5-HT1B is malleable, populating a number of distinct conformations. Elevated cholesterol density near transmembrane helix 4 is considered to be conducive to the conformation of extracellular loop 2. Occupation of this site is also shown to be stereospecific, illustrated by differential behavior of nat-cholesterol isomers, ent- and epi-cholesterol. In simulations containing the endogenous agonist, serotonin, cholesterol binding at transmembrane helix 4 biases bound serotonin molecules toward an unexpected binding mode in the extended binding pocket. The results highlight the capability of membrane cholesterol to influence the mobility of the extracellular surface in the 5-HT1 receptor family and manipulate the architecture of the extracellular ligand-binding pocket.
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Affiliation(s)
- Victoria Oakes
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Carmen Domene
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK; Department of Chemistry, University of Oxford, Oxford, OX1 3TA, Oxford, UK.
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24
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Liu R, Kinoshita M, Adolfi MC, Schartl M. Analysis of the Role of the Mc4r System in Development, Growth, and Puberty of Medaka. Front Endocrinol (Lausanne) 2019; 10:213. [PMID: 31024451 PMCID: PMC6463759 DOI: 10.3389/fendo.2019.00213] [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: 12/12/2018] [Accepted: 03/18/2019] [Indexed: 01/23/2023] Open
Abstract
In mammals the melanocortin 4 receptor (Mc4r) signaling system has been mainly associated with the regulation of appetite and energy homeostasis. In fish of the genus Xiphophorus (platyfish and swordtails) puberty onset is genetically determined by a single locus, which encodes the mc4r. Wild populations of Xiphophorus are polymorphic for early and late-maturing individuals. Copy number variation of different mc4r alleles is responsible for the difference in puberty onset. To answer whether this is a special adaptation of the Mc4r signaling system in the lineage of Xiphophorus or a more widely conserved mechanism in teleosts, we studied the role of Mc4r in reproductive biology of medaka (Oryzias latipes), a close relative to Xiphophorus and a well-established model to study gonadal development. To understand the potential role of Mc4r in medaka, we characterized the major features of the Mc4r signaling system (mc4r, mrap2, pomc, agrp1). In medaka, all these genes are expressed before hatching. In adults, they are mainly expressed in the brain. The transcript of the receptor accessory protein mrap2 co-localizes with mc4r in the hypothalamus in adult brains indicating a conserved function of modulating Mc4r signaling. Comparing growth and puberty between wild-type and mc4r knockout medaka revealed that absence of Mc4r does not change puberty timing but significantly delays hatching. Embryonic development of knockout animals is retarded compared to wild-types. In conclusion, the Mc4r system in medaka is involved in regulation of growth rather than puberty.
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Affiliation(s)
- Ruiqi Liu
- Physiological Chemistry, Biocenter, University of Wuerzburg, Wuerzburg, Germany
| | - Masato Kinoshita
- Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Mateus C Adolfi
- Physiological Chemistry, Biocenter, University of Wuerzburg, Wuerzburg, Germany
| | - Manfred Schartl
- Physiological Chemistry, Biocenter, University of Wuerzburg, Wuerzburg, Germany
- Comprehensive Cancer Center Mainfranken, University Clinic Wuerzburg, Wuerzburg, Germany
- Hagler Institute for Advanced Study and Department of Biology, Texas A&M University, College Station, TX, United States
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25
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Heyder N, Kleinau G, Szczepek M, Kwiatkowski D, Speck D, Soletto L, Cerdá-Reverter JM, Krude H, Kühnen P, Biebermann H, Scheerer P. Signal Transduction and Pathogenic Modifications at the Melanocortin-4 Receptor: A Structural Perspective. Front Endocrinol (Lausanne) 2019; 10:515. [PMID: 31417496 PMCID: PMC6685040 DOI: 10.3389/fendo.2019.00515] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 07/15/2019] [Indexed: 12/19/2022] Open
Abstract
The melanocortin-4 receptor (MC4R) can be endogenously activated by binding of melanocyte-stimulating hormones (MSH), which mediates anorexigenic effects. In contrast, the agouti-related peptide (AgRP) acts as an endogenous inverse agonist and suppresses ligand-independent basal signaling activity (orexigenic effects). Binding of ligands to MC4R leads to the activation of different G-protein subtypes or arrestin and concomitant signaling pathways. This receptor is a key protein in the hypothalamic regulation of food intake and energy expenditure and naturally-occurring inactivating MC4R variants are the most frequent cause of monogenic obesity. In general, obesity is a growing problem on a global scale and is of social, medical, and economic relevance. A significant goal is to develop optimized pharmacological tools targeting MC4R without adverse effects. To date, this has not been achieved because of inter alia non-selective ligands across the five functionally different MCR subtypes (MC1-5R). This motivates further investigation of (i) the three-dimensional MC4R structure, (ii) binding mechanisms of various ligands, and (iii) the molecular transfer process of signal transduction, with the aim of understanding how structural features are linked with functional-physiological aspects. Unfortunately, experimentally elucidated structural information is not yet available for the MC receptors, a group of class A G-protein coupled receptors (GPCRs). We, therefore, generated MC4R homology models and complexes with interacting partners to describe approximate structural properties associated with signaling mechanisms. In addition, molecular insights from pathogenic mutations were incorporated to discriminate more precisely their individual malfunction of the signal transfer mechanism.
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Affiliation(s)
- Nicolas Heyder
- Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Gunnar Kleinau
- Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- *Correspondence: Gunnar Kleinau
| | - Michal Szczepek
- Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Dennis Kwiatkowski
- Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - David Speck
- Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Lucia Soletto
- Departamento de Fisiología de Peces y Biotecnología, Consejo Superior de Investigaciones Científicas, Instituto de Acuicultura Torre de la Sal, Ribera de Cabanes, Spain
| | - José Miguel Cerdá-Reverter
- Departamento de Fisiología de Peces y Biotecnología, Consejo Superior de Investigaciones Científicas, Instituto de Acuicultura Torre de la Sal, Ribera de Cabanes, Spain
| | - Heiko Krude
- Institute of Experimental Pediatric Endocrinology, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Peter Kühnen
- Institute of Experimental Pediatric Endocrinology, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Heike Biebermann
- Institute of Experimental Pediatric Endocrinology, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Patrick Scheerer
- Group Protein X-ray Crystallography and Signal Transduction, Institute of Medical Physics and Biophysics, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Patrick Scheerer
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26
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Gupta MK, Mohan ML, Naga Prasad SV. G Protein-Coupled Receptor Resensitization Paradigms. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2018; 339:63-91. [PMID: 29776605 DOI: 10.1016/bs.ircmb.2018.03.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cellular responses to extracellular milieu/environment are driven by cell surface receptors that transmit the signal into the cells resulting in a synchronized and measured response. The ability to provide such exquisite responses to changes in external environment is mediated by the tight and yet, deliberate regulation of cell surface receptor function. In this regard, the seven transmembrane G protein-coupled receptors (GPCRs) are the largest family of cell surface receptors that regulate responses like cardiac contractility, vision, and olfaction including platelet activation. GPCRs regulate these plethora of events through GPCR-activation, -desensitization, and -resensitization. External stimuli (ligands or agonists) activate GPCR initiating downstream signals. The activated GPCR undergoes inactivation or desensitization by phosphorylation and binding of β-arrestin resulting in diminution of downstream signals. The desensitized GPCRs are internalized into endosomes, wherein they undergo dephosphorylation or resensitization by protein phosphatase to be recycled back to the cell membrane as naïve GPCR ready for the next wave of stimuli. Despite the knowledge that activation, desensitization, and resensitization shoulder an equal role in maintaining GPCR function, major advances have been made in understanding activation and desensitization compared to resensitization. However, increasing evidence shows that resensitization is exquisitely regulated process, thereby contributing to the dynamic regulation of GPCR function. In recognition of these observations, in this chapter we discuss the key advances on the mechanistic underpinning that drive and regulate GPCR function with a focus on resensitization.
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Affiliation(s)
- Manveen K Gupta
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Maradumane L Mohan
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Sathyamangla V Naga Prasad
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States.
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27
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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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28
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Siljee JE, Wang Y, Bernard AA, Ersoy BA, Zhang S, Marley A, Von Zastrow M, Reiter JF, Vaisse C. Subcellular localization of MC4R with ADCY3 at neuronal primary cilia underlies a common pathway for genetic predisposition to obesity. Nat Genet 2018; 50:180-185. [PMID: 29311635 PMCID: PMC5805646 DOI: 10.1038/s41588-017-0020-9] [Citation(s) in RCA: 148] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 11/15/2017] [Indexed: 02/01/2023]
Affiliation(s)
- Jacqueline E Siljee
- Department of Medicine and Diabetes Center, University of California, San Francisco, San Francisco, CA, USA
| | - Yi Wang
- Department of Medicine and Diabetes Center, University of California, San Francisco, San Francisco, CA, USA
| | - Adelaide A Bernard
- Department of Medicine and Diabetes Center, University of California, San Francisco, San Francisco, CA, USA
| | - Baran A Ersoy
- Department of Medicine and Diabetes Center, University of California, San Francisco, San Francisco, CA, USA.,Department of Medicine, Weill Cornell Medical College, New York, NY, USA
| | - Sumei Zhang
- Department of Medicine and Diabetes Center, University of California, San Francisco, San Francisco, CA, USA
| | - Aaron Marley
- Department of Psychiatry and Cellular & Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA
| | - Mark Von Zastrow
- Department of Psychiatry and Cellular & Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA
| | - Jeremy F Reiter
- Department of Biochemistry and Biophysics, Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA
| | - Christian Vaisse
- Department of Medicine and Diabetes Center, University of California, San Francisco, San Francisco, CA, USA.
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29
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Palmer D, Gonçalves JPL, V Hansen L, Wu B, Hald H, Schoffelen S, Diness F, Le Quement ST, Nielsen TE, Meldal M. Click-Chemistry-Mediated Synthesis of Selective Melanocortin Receptor 4 Agonists. J Med Chem 2017; 60:8716-8730. [PMID: 28972753 DOI: 10.1021/acs.jmedchem.7b00353] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The melanocortin receptor 4 (MC4R) subtype of the melanocortin receptor family is a target for therapeutics to ameliorate metabolic dysfunction. Endogenous MC4R agonists possess a critical pharmacophore (HFRW), and cyclization of peptide agonists often enhances potency. Thus, 17 cyclized peptides were synthesized by solid phase click chemistry to develop novel, potent, selective MC4R agonists. Using cAMP measurements and a transcriptional reporter assay, we observed that several constrained agonists generated by a cycloaddition reaction displayed high selectivity (223- to 467-fold) toward MC4R over MC3R and MC5R receptor subtypes without compromising agonist potency. Significant variation was also observed between the EC50 values for the two assays, with robust levels of reporter expression measured at lower concentrations than those effecting appreciable increases in cAMP levels for the majority of the compounds tested. Collectively, we characterized significant elements that modulate the activity of the core pharmacophore for MC4R and provide a rationale for careful assay selection for agonist screening.
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Affiliation(s)
- Daniel Palmer
- CECB, Department of Chemistry, University of Copenhagen , Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Juliana P L Gonçalves
- CECB, Department of Chemistry, University of Copenhagen , Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Louise V Hansen
- CECB, Department of Chemistry, University of Copenhagen , Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Boqian Wu
- Aquaporin A/S , Ole Maaløes Vej 3, 2200 Copenhagen, Denmark
| | - Helle Hald
- CECB, Department of Chemistry, University of Copenhagen , Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Sanne Schoffelen
- CECB, Department of Chemistry, University of Copenhagen , Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Frederik Diness
- CECB, Department of Chemistry, University of Copenhagen , Universitetsparken 5, 2100 Copenhagen, Denmark
| | | | - Thomas E Nielsen
- Protein & Peptide Chemistry, Novo Nordisk A/S , Novo Nordisk Park, 2760 Måløv, Denmark.,Department of Immunology and Microbiology, University of Copenhagen , Blegdamsvej 3B, 2200 Copenhagen, Denmark.,Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University , 60 Nanyang Drive, SG 637551, Singapore
| | - Morten Meldal
- CECB, Department of Chemistry, University of Copenhagen , Universitetsparken 5, 2100 Copenhagen, Denmark
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30
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Uddin MS, Naider F, Becker JM. Dynamic roles for the N-terminus of the yeast G protein-coupled receptor Ste2p. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:2058-2067. [PMID: 28754538 DOI: 10.1016/j.bbamem.2017.07.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 07/13/2017] [Accepted: 07/24/2017] [Indexed: 12/11/2022]
Abstract
The Saccharomyces cerevisiae α-factor receptor Ste2p has been used extensively as a model to understand the molecular mechanism of signal transduction by G protein-coupled receptors (GPCRs). Single and double cysteine mutants of Ste2p were created and served as surrogates to detect intramolecular interactions and dimerization of Ste2p using disulfide cross-linking methodology. When a mutation was introduced into the phylogenetically conserved tyrosine residue at position 26 (Y26C) in the N-terminus of Ste2p, dimerization was increased greatly. The amount of dimer formed by this Y26C mutant was greatly reduced by ligand binding even though the ligand binding site is far removed from the N-terminus; the lowering of the dimer formation was consistent with a conformational change in the N-terminus of the receptor upon activation. Dimerization was decreased by double mutations Y26C/V109C or Y26C/T114C indicating that Y26 is in close proximity to V109 and T114 of extracellular loop 1 in native Ste2p. Combined with earlier studies, these results indicate previously unrecognized roles for the N-terminus of Ste2p, and perhaps of GPCRs in general, and reveal a specific N-terminus residue or region, that is involved in GPCR signaling, intrareceptor interactions, and receptor dimerization.
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Affiliation(s)
- M Seraj Uddin
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Fred Naider
- Department of Chemistry and Macromolecular Assemblies Institute, College of Staten Island, CUNY, New York, New York 10314, United States; Ph.D. Programs in Biochemistry and Chemistry, The Graduate Center of the City University of New York, New York, NY 10016, United States
| | - Jeffrey M Becker
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, United States.
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31
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Troupiotis-Tsaïlaki A, Zachmann J, González-Gil I, Gonzalez A, Ortega-Gutiérrez S, López-Rodríguez ML, Pardo L, Govaerts C. Ligand chain length drives activation of lipid G protein-coupled receptors. Sci Rep 2017; 7:2020. [PMID: 28515494 PMCID: PMC5435731 DOI: 10.1038/s41598-017-02104-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 04/07/2017] [Indexed: 01/20/2023] Open
Abstract
Sphingosine-1-phosphate (S1P) is a lipid mediator that can activate five cell membrane G protein-coupled receptors (GPCRs) which carry a variety of essential functions and are promising drug targets. S1P is composed of a polar zwitterionic head-group and a hydrophobic alkyl chain. This implies an activation mechanism of its cognate receptor that must be significantly different from what is known for prototypical GPCRs (ie receptor to small hydrophilic ligands). Here we aim to identify the structural features responsible for S1P agonism by combining molecular dynamics simulations and functional assays using S1P analogs of different alkyl chain lengths. We propose that high affinity binding involves polar interactions between the lipid head-group and receptor side chains while activation is due to hydrophobic interactions between the lipid tail and residues in a distinct binding site. We observe that ligand efficacy is directly related to alkyl chain length but also varies with receptor subtypes in correlation with the size of this binding pocket. Integrating experimental and computational data, we propose an activation mechanism for the S1P receptors involving agonist-induced conformational events that are conserved throughout class A GPCRs.
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Affiliation(s)
| | - Julian Zachmann
- Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain
| | - Inés González-Gil
- Departamento de Química Orgánica I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, E-28040, Madrid, Spain
| | - Angel Gonzalez
- Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain
| | - Silvia Ortega-Gutiérrez
- Departamento de Química Orgánica I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, E-28040, Madrid, Spain
| | - Maria L López-Rodríguez
- Departamento de Química Orgánica I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, E-28040, Madrid, Spain
| | - Leonardo Pardo
- Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain.
| | - Cedric Govaerts
- Laboratoire de Structure et Fonction des Membranes Biologiques, Université Libre de Bruxelles, Brussels, Belgium.
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32
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Sun X, Laroche G, Wang X, Ågren H, Bowman GR, Giguère PM, Tu Y. Propagation of the Allosteric Modulation Induced by Sodium in the δ-Opioid Receptor. Chemistry 2017; 23:4615-4624. [PMID: 28182309 DOI: 10.1002/chem.201605575] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Indexed: 11/07/2022]
Abstract
Allosteric sodium in the helix bundle of a G protein-coupled receptor (GPCR) can modulate the receptor activation on the intracellular side. This phenomenon has confounded the GPCR community for decades. In this work, we present a theoretical model that reveals the mechanism of the allosteric modulation induced by sodium in the δ-opioid receptor. We found that the allosteric sodium ion exploits a distinct conformation of the key residue Trp2746.48 to propagate the modulation to helices 5 and 6, which further transmits along the helices and regulates their positions on the intracellular side. This mechanism is supported by subsequent functional assays. Remarkably, our results highlight the contrast between the allosteric effects towards two GPCR partners, the G protein and β-arrestin, as indicated by the fact that the allosteric modulation initiated by the sodium ion significantly affects the β-arrestin recruitment, while it alters the G protein signaling only moderately. We believe that the mechanism revealed in this work can be used to explain allosteric effects initiated by sodium in other GPCRs since the allosteric sodium is highly conserved across GPCRs.
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Affiliation(s)
- Xianqiang Sun
- Pharmaceutical Research Center, School of Pharmacy, Guangzhou Medical University, 195 Dongfengxi Rd, Guangzhou, 510182, China
- Division of Theoretical Chemistry and Biology, School of Biotechnology, KTH Royal Institute of Technology, 106 91, Stockholm, Sweden
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, 63110, USA
| | - Genevieve Laroche
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Rd, Ottawa, ON, Canada
| | - Xu Wang
- Division of Theoretical Chemistry and Biology, School of Biotechnology, KTH Royal Institute of Technology, 106 91, Stockholm, Sweden
| | - Hans Ågren
- Division of Theoretical Chemistry and Biology, School of Biotechnology, KTH Royal Institute of Technology, 106 91, Stockholm, Sweden
| | - Gregory R Bowman
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, 63110, USA
| | - Patrick M Giguère
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Rd, Ottawa, ON, Canada
| | - Yaoquan Tu
- Division of Theoretical Chemistry and Biology, School of Biotechnology, KTH Royal Institute of Technology, 106 91, Stockholm, Sweden
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33
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Coleman JLJ, Ngo T, Smith NJ. The G protein-coupled receptor N-terminus and receptor signalling: N-tering a new era. Cell Signal 2017; 33:1-9. [PMID: 28188824 DOI: 10.1016/j.cellsig.2017.02.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 02/06/2017] [Indexed: 01/22/2023]
Abstract
G protein-coupled receptors (GPCRs) are a vast family of membrane-traversing proteins, essential to the ability of eukaryotic life to detect, and mount an intracellular response to, a diverse range of extracellular stimuli. GPCRs have evolved with archetypal features including an extracellular N-terminus and intracellular C-terminus that flank a transmembrane structure of seven sequential helices joined by intracellular and extracellular loops. These structural domains contribute to the ability of a GPCR to be correctly synthesised and inserted into the cell membrane, to interact with its cognate ligand(s) and to couple with signal-transducing heterotrimeric G proteins, allowing the activated receptor to selectively modulate a number of signalling cascades. Whilst well known for its importance in receptor translation and trafficking, the GPCR N-terminus is underexplored as a participant in receptor signalling. This review aims to discuss and integrate recent advances in knowledge of the vital roles of the GPCR N-terminus in receptor signalling.
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Affiliation(s)
- James L J Coleman
- Molecular Pharmacology Group, Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; St Vincent's Clinical School, University of New South Wales, Darlinghurst, NSW 2010, Australia.
| | - Tony Ngo
- Molecular Pharmacology Group, Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; St Vincent's Clinical School, University of New South Wales, Darlinghurst, NSW 2010, Australia
| | - Nicola J Smith
- Molecular Pharmacology Group, Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; St Vincent's Clinical School, University of New South Wales, Darlinghurst, NSW 2010, Australia.
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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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Coleman JLJ, Ngo T, Schmidt J, Mrad N, Liew CK, Jones NM, Graham RM, Smith NJ. Metalloprotease cleavage of the N terminus of the orphan G protein-coupled receptor GPR37L1 reduces its constitutive activity. Sci Signal 2016; 9:ra36. [PMID: 27072655 DOI: 10.1126/scisignal.aad1089] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Little is known about the pharmacology or physiology of GPR37L1, a G protein (heterotrimeric guanine nucleotide-binding protein)-coupled receptor that is abundant in the cerebellum. Mice deficient in this receptor exhibit precocious cerebellar development and hypertension. We showed that GPR37L1 coupled to the G protein Gα(s) when heterologously expressed in cultured cells in the absence of any added ligand, whereas a mutant receptor that lacked the amino terminus was inactive. Conversely, inhibition of ADAMs (a disintegrin and metalloproteases) enhanced receptor activity, indicating that the presence of the amino terminus is necessary for GPR37L1 signaling. Metalloprotease-dependent processing of GPR37L1 was evident in rodent cerebellum, where we detected predominantly the cleaved, inactive form. However, comparison of the accumulation of cAMP (adenosine 3',5'-monophosphate) in response to phosphodiesterase inhibition in cerebellar slice preparations from wild-type and GPR37L1-null mice showed that some constitutive signaling remained in the wild-type mice. In reporter assays of Gα(s) or Gα(i) signaling, the synthetic, prosaposin-derived peptide prosaptide (TX14A) did not increase GPR37L1 activity. Our data indicate that GPR37L1 may be a constitutively active receptor, or perhaps its ligand is present under the conditions that we used for analysis, and that the activity of this receptor is instead controlled by signals that regulate metalloprotease activity in the tissue.
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Affiliation(s)
- James L J Coleman
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales 2010, Australia. St Vincent's Clinical School, University of New South Wales, Darlinghurst, New South Wales 2010, Australia
| | - Tony Ngo
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales 2010, Australia. St Vincent's Clinical School, University of New South Wales, Darlinghurst, New South Wales 2010, Australia
| | - Johannes Schmidt
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales 2010, Australia
| | - Nadine Mrad
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales 2010, Australia
| | - Chu Kong Liew
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales 2010, Australia
| | - Nicole M Jones
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Kensington, New South Wales 2033, Australia
| | - Robert M Graham
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales 2010, Australia. St Vincent's Clinical School, University of New South Wales, Darlinghurst, New South Wales 2010, Australia
| | - Nicola J Smith
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales 2010, Australia. St Vincent's Clinical School, University of New South Wales, Darlinghurst, New South Wales 2010, Australia.
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The N-terminus of the yeast G protein-coupled receptor Ste2p plays critical roles in surface expression, signaling, and negative regulation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:715-24. [PMID: 26707753 DOI: 10.1016/j.bbamem.2015.12.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 11/18/2015] [Accepted: 12/15/2015] [Indexed: 12/23/2022]
Abstract
G protein-coupled receptors (GPCRs) are found in all eukaryotic cells examined to date where they function as membrane-bound proteins that bind a multitude of extracellular ligands to initiate intracellular signal transduction systems controlling cellular physiology. GPCRs have seven heptahelical membrane spanning domains connected by extracellular and intracellular loops with an extracellular N-terminus and an intracellular C-terminus. The N-terminus has been the least studied domain of most GPCRs. The yeast Ste2p protein, the receptor for the thirteen amino acid peptide pheromone α-factor, has been used extensively as a model to study GPCR structure and function. In this study we constructed a number of deletions of the Ste2p N-terminus and uncovered an unexpected function as a negative regulatory domain. We examined the role of the N-terminus in expression, signaling function and ligand-binding properties and found that the residues 11-30 play a critical role in receptor expression on the cell surface. The studies also indicated that residues 2-10 of the N-terminus are involved in negative regulation of signaling as shown by the observation that deletion of these residues enhanced mating and gene induction. Furthermore, our results indicated that the residues 21-30 are essential for optimal signaling. Overall, we propose that the N-terminus of Ste2p plays multiple regulatory roles in controlling receptor function.
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Functional elements of the gastric inhibitory polypeptide receptor: Comparison between secretin- and rhodopsin-like G protein-coupled receptors. Biochem Pharmacol 2015; 96:237-46. [PMID: 26043830 DOI: 10.1016/j.bcp.2015.05.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 05/28/2015] [Indexed: 12/25/2022]
Abstract
Innovative crystallographic techniques have resulted in an exponential growth in the number of solved G-protein coupled receptor (GPCR) structures and a better understanding of the mechanisms of class A receptor activation and G protein binding. The recent release of the type 1 receptor for the corticotropin-releasing factor and the glucagon receptor structures, two members of the secretin-like family, gives the opportunity to understand these mechanisms of activation in this family of GPCRs. Here, we addressed the comparison of the functional elements of class A and secretin-like GPCRs, using the glucose-dependent insulinotropic polypeptide receptor (GIPR) as a model receptor. Inactive and active models of GIPR permitted to select, by structural homology with class A GPCRs, several residues that may form key interactions presumably involved in receptor activation and Gs coupling, for pharmacological evaluation. Mutants on these amino acids were expressed in HEKT 293 cells and characterized in terms of GIP-induced cAMP production. We identified various functional domains spanning from the peptide-binding to the G protein pockets: including: a network linking the extracellular part of transmembrane (TM) 6 with TMs 2 and 7; a polar lock that resembles the ionic-lock in class A GPCRs; an interaction between TMs 3 and 7 that favors activation; and two clusters of polar/charged and of hydrophobic residues that interact with the C-terminus of the Gα. The results show that despite the low degree of sequence similarity between rhodopsin- and secretin-like GPCRs, the two families share conserved elements in their mechanisms of activation and G protein binding.
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Tao YX. Constitutive activity in melanocortin-4 receptor: biased signaling of inverse agonists. ADVANCES IN PHARMACOLOGY 2015; 70:135-54. [PMID: 24931195 DOI: 10.1016/b978-0-12-417197-8.00005-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The melanocortin-4 receptor (MC4R) is a critical regulator of energy homeostasis, including both energy intake and energy expenditure. It mediates the actions of a number of hormones on energy balance. The endogenous ligands for MC4R include peptide agonists derived from processing of proopiomelanocortin and the antagonist Agouti-related peptide (AgRP). Wild-type MC4R has some basal (constitutive) activity. Naturally occurring and laboratory-generated mutations have been identified, which results in either increased or decreased basal activities. Impaired basal signaling has been suggested to be a cause of dysregulated energy homeostasis and early-onset obesity, although several constitutively active mutations have also been identified from obese patients. AgRP and several small-molecule antagonists have been shown to be inverse agonists in the Gs-cAMP pathway. However, in the extracellular signal-regulated kinase (ERK) 1/2 pathway, we showed that these inverse agonists are potent agonists, demonstrating convincingly that they are biased ligands. We also showed that some mutations that do not cause constitutive activation in the Gs-cAMP pathway cause constitutive activation in the ERK1/2 pathway, suggesting that they are biased receptors. The physiological and potential pathophysiological relevance of the biased constitutive signaling in MC4R and therapeutic potential remain to be investigated.
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Affiliation(s)
- Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, Alabama, USA.
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Yun JH, Kim K, Jung Y, Park JH, Cho HS, Lee W. Co-expression of human agouti-related protein enhances expression and stability of human melanocortin-4 receptor. Biochem Biophys Res Commun 2015; 456:116-21. [PMID: 25446108 DOI: 10.1016/j.bbrc.2014.11.044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2014] [Accepted: 11/14/2014] [Indexed: 11/30/2022]
Abstract
G protein-coupled receptors (GPCRs) represent the largest family of transmembrane signaling proteins, and they are considered major targets of approximately half of all therapeutic agents. Human melanocortin-4 receptor (hMC4R) plays an important role in the control of energy homeostasis, and its mutants are directly related to severe human obesity. Here, we describe optimized protocols for the high-yield expression and purification of hMC4R that will accelerate structural study. Truncations of the N- and C-termini of hMC4R with T4 lysozyme (T4L) insertion increase the solubility as well as stability of the protein. Strikingly, co-expression of human mini-agouti-related protein (mini-AgRP) in Spodoptera frugiperda (Sf9) cells enables excellent stability of hMC4R. The protein yield in the human mini-AgRP co-expression system is increased by about 3-4 times compared to that of hMC4R alone. Data from analytical size exclusion chromatography (aSEC) and thermostability assay show that hMC4R becomes homogeneous and stable with a melting temperature of 58°C in the presence of human mini-AgRP.
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Affiliation(s)
- Ji-Hye Yun
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea
| | - Kuglae Kim
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea
| | - Youngjin Jung
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea
| | - Jae-Hyun Park
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea
| | - Hyun-Soo Cho
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea
| | - Weontae Lee
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea.
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40
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Ahmad R, Wojciech S, Jockers R. Hunting for the function of orphan GPCRs - beyond the search for the endogenous ligand. Br J Pharmacol 2014; 172:3212-28. [PMID: 25231237 DOI: 10.1111/bph.12942] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 09/04/2014] [Accepted: 09/09/2014] [Indexed: 12/13/2022] Open
Abstract
Seven transmembrane-spanning proteins (7TM), also called GPCRs, are among the most versatile and evolutionary successful protein families. Out of the 400 non-odourant members identified in the human genome, approximately 100 remain orphans that have not been matched with an endogenous ligand. Apart from the classical deorphanization strategies, several alternative strategies provided recent new insights into the function of these proteins, which hold promise for high therapeutic potential. These alternative strategies consist of the phenotypical characterization of organisms silenced or overexpressing orphan 7TM proteins, the search for constitutive receptor activity and formation of protein complexes including 7TM proteins as well as the development of synthetic, surrogate ligands. Taken together, a variety of ligand-independent functions can be attributed to orphan 7TM proteins that range from constitutive activity to complex formation with other proteins and include 'true' orphans for which no ligand exist and 'conditional' orphans that behave like orphans in the absence of ligand and as non-orphans in the presence of ligand.
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Affiliation(s)
- Raise Ahmad
- Institut Cochin, INSERM, Paris, France.,CNRS UMR 8104, Paris, France.,Paris Descartes University, Paris, France
| | - Stefanie Wojciech
- Institut Cochin, INSERM, Paris, France.,CNRS UMR 8104, Paris, France.,Paris Descartes University, Paris, France
| | - Ralf Jockers
- Institut Cochin, INSERM, Paris, France.,CNRS UMR 8104, Paris, France.,Paris Descartes University, Paris, France
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Cortés R, Navarro S, Agulleiro MJ, Guillot R, García-Herranz V, Sánchez E, Cerdá-Reverter JM. Evolution of the melanocortin system. Gen Comp Endocrinol 2014; 209:3-10. [PMID: 24768673 DOI: 10.1016/j.ygcen.2014.04.005] [Citation(s) in RCA: 43] [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: 01/07/2014] [Revised: 04/01/2014] [Accepted: 04/03/2014] [Indexed: 11/17/2022]
Abstract
The melanocortin system is one of the most complex of the hormonal systems. It involves different agonists encoded in the multiplex precursor proopiomelanocortin (POMC) or in different genes as β-defensins, endogenous antagonist, like agouti-signalling protein (ASIP) or agouti-related protein (AGRP), and five different melanocortin receptors (MCRs). Rounds of whole genome duplication events have preceded the functional and molecular diversification of the family in addition some co-evolutionary and tandem duplication processes have been proposed. The evolutionary patterns of the different partners are controversial and different hypotheses have emerged from a study of the sequenced genomes. In this review, we summarize the different evolutionary hypotheses proposed for the different melanocortin partners.
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Affiliation(s)
- Raúl Cortés
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas (IATS-CSIC), Ribera de Cabanes, Castellón, Spain
| | - Sandra Navarro
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas (IATS-CSIC), Ribera de Cabanes, Castellón, Spain
| | - Maria Josep Agulleiro
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas (IATS-CSIC), Ribera de Cabanes, Castellón, Spain
| | - Raúl Guillot
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas (IATS-CSIC), Ribera de Cabanes, Castellón, Spain
| | - Víctor García-Herranz
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas (IATS-CSIC), Ribera de Cabanes, Castellón, Spain
| | - Elisa Sánchez
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas (IATS-CSIC), Ribera de Cabanes, Castellón, Spain
| | - José Miguel Cerdá-Reverter
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas (IATS-CSIC), Ribera de Cabanes, Castellón, Spain.
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42
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Agulleiro MJ, Cortés R, Leal E, Ríos D, Sánchez E, Cerdá-Reverter JM. Characterization, tissue distribution and regulation by fasting of the agouti family of peptides in the sea bass (Dicentrarchus labrax). Gen Comp Endocrinol 2014; 205:251-9. [PMID: 24561275 DOI: 10.1016/j.ygcen.2014.02.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 02/05/2014] [Accepted: 02/11/2014] [Indexed: 01/11/2023]
Abstract
The melanocortin system is one of the most complex hormonal systems in vertebrates. Atypically, the signaling of melanocortin receptors is regulated by the binding of endogenous antagonists, named agouti-signaling protein (ASIP) and agouti-related protein (AGRP). Teleost specific genome duplication (TSGD) rendered new gene copies in teleost fish and up to four different genes of the agouti family of peptides have been characterized. In this paper, molecular cloning was used to characterize mRNA of the agouti family of peptides in sea bass. Four different genes were identified: AGRP1, ASIP1, AGRP2 and ASIP2. The AGRP1 gene is mainly expressed in the brain whereas ASIP1 is mainly expressed in the ventral skin. Both ASIP2 and AGRP2 are expressed in the brain and the pineal gland but also in some peripheral tissues. Immunocytochemical studies demonstrated that AGRP1 is exclusively expressed within the lateral tuberal nucleus, the homologue of the mammalian arcuate nucleus in fish. Long-term fasting (8-29 days) increased the hypothalamic expression of AGRP1 but depressed AGRP2 expression (15-29 days). In contrast, the hypothalamic expression of ASIP2 was upregulated during short-term fasting suggesting that this peptide could be involved in the short term regulation of food intake in the sea bass.
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Affiliation(s)
- Maria Josep Agulleiro
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas (IATS-CSIC), Ribera de Cabanes, Castellón, Spain
| | - Raúl Cortés
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas (IATS-CSIC), Ribera de Cabanes, Castellón, Spain
| | - Esther Leal
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas (IATS-CSIC), Ribera de Cabanes, Castellón, Spain
| | - Diana Ríos
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas (IATS-CSIC), Ribera de Cabanes, Castellón, Spain
| | - Elisa Sánchez
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas (IATS-CSIC), Ribera de Cabanes, Castellón, Spain
| | - José Miguel Cerdá-Reverter
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas (IATS-CSIC), Ribera de Cabanes, Castellón, Spain.
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Spyridaki K, Matsoukas MT, Cordomi A, Gkountelias K, Papadokostaki M, Mavromoustakos T, Logothetis DE, Margioris AN, Pardo L, Liapakis G. Structural-functional analysis of the third transmembrane domain of the corticotropin-releasing factor type 1 receptor: role in activation and allosteric antagonism. J Biol Chem 2014; 289:18966-77. [PMID: 24838244 DOI: 10.1074/jbc.m113.544460] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The corticotropin-releasing factor (CRF) type 1 receptor (CRF1R) for the 41-amino acid peptide CRF is a class B G protein-coupled receptor, which plays a key role in the response of our body to stressful stimuli and the maintenance of homeostasis by regulating neural and endocrine functions. CRF and related peptides, such as sauvagine, bind to the extracellular regions of CRF1R and activate the receptor. In contrast, small nonpeptide antagonists, which are effective against stress-related disorders, such as depression and anxiety, have been proposed to interact with the helical transmembrane domains (TMs) of CRF1R and allosterically antagonize peptide binding and receptor activation. Here, we aimed to elucidate the role of the third TM (TM3) in the molecular mechanisms underlying activation of CRF1R. TM3 was selected because its tilted orientation, relative to the membrane, allows its residues to establish key interactions with ligands, other TM helices, and the G protein. Using a combination of pharmacological, biochemical, and computational approaches, we found that Phe-203(3.40) and Gly-210(3.47) in TM3 play an important role in receptor activation. Our experimental findings also suggest that Phe-203(3.40) interacts with nonpeptide antagonists.
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Affiliation(s)
| | - Minos-Timotheos Matsoukas
- the Laboratori de Medicina Computacional, Facultat de Medicina, Universitat Autonoma de Barcelona, Bellaterra 08193, Spain
| | - Arnau Cordomi
- the Laboratori de Medicina Computacional, Facultat de Medicina, Universitat Autonoma de Barcelona, Bellaterra 08193, Spain
| | | | | | - Thomas Mavromoustakos
- the Laboratory of Organic Chemistry, Department of Chemistry, University of Athens, Athens 11571, Greece, and
| | - Diomedes E Logothetis
- the Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, Virginia 23298
| | - Andrew N Margioris
- Clinical Chemistry, School of Medicine, University of Crete, Heraklion 71003, Greece
| | - Leonardo Pardo
- the Laboratori de Medicina Computacional, Facultat de Medicina, Universitat Autonoma de Barcelona, Bellaterra 08193, Spain
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Shpakova EA, Derkach KV, Shpakov AO. Effect of Peptides Corresponding to Extracellular Domains of Serotonin 1B/1D Receptors and Melanocortin 3 and 4 Receptors on Hormonal Regulation of Adenylate Cyclase in Rat Brain. Bull Exp Biol Med 2014; 156:658-62. [DOI: 10.1007/s10517-014-2419-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Indexed: 11/24/2022]
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45
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Gonzalez A, Cordomí A, Matsoukas M, Zachmann J, Pardo L. Modeling of G Protein-Coupled Receptors Using Crystal Structures: From Monomers to Signaling Complexes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 796:15-33. [DOI: 10.1007/978-94-007-7423-0_2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Coll AP. “Are melanocortin receptors constitutively active in vivo?”. Eur J Pharmacol 2013; 719:202-207. [DOI: 10.1016/j.ejphar.2013.04.051] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 03/22/2013] [Accepted: 04/03/2013] [Indexed: 10/26/2022]
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Belmer A, Doly S, Setola V, Banas SM, Moutkine I, Boutourlinsky K, Kenakin T, Maroteaux L. Role of the N-terminal region in G protein-coupled receptor functions: negative modulation revealed by 5-HT2B receptor polymorphisms. Mol Pharmacol 2013; 85:127-38. [PMID: 24174497 DOI: 10.1124/mol.113.089086] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The putative role of the N-terminal region of rhodopsin-like 7 transmembrane biogenic amine receptors in agonist-induced signaling has not yet been clarified despite recent advances in 7 transmembrane receptor structural biology. Given the existence of N-terminal nonsynonymous polymorphisms (R6G;E42G) within the HTR2B gene in a drug-abusing population, we assessed whether these polymorphisms affect 5-hydroxytryptamine 2B (5-HT2B) receptor in vitro pharmacologic and coupling properties in transfected COS-7 cells. Modification of the 5-HT2B receptor N terminus by the R6G;E42G polymorphisms increases such agonist signaling pathways as inositol phosphate accumulation as assessed by either classic or operational models. The N-terminal R6G;E42G mutations of the 5-HT2B receptor also increase cell proliferation and slow its desensitization kinetics compared with the wild-type receptor, further supporting a role for the N terminus in transduction efficacy. Furthermore, by coexpressing a tethered wild-type 5-HT2B receptor N terminus with a 5-HT2B receptor bearing a N-terminal deletion, we were able to restore original coupling. This reversion to normal activity of a truncated 5-HT2B receptor by coexpression of the membrane-tethered wild-type 5-HT2B receptor N terminus was not observed using a membrane-tethered 5-HT2B receptor R6G;E42G N terminus. These data suggest that the N terminus exerts a negative control over basal as well as agonist-stimulated receptor activity that is lost in the R6G;E42G mutant. Our findings reveal a new and unanticipated role of the 5-HT2B receptor N terminus as a negative modulator, affecting both constitutive and agonist-stimulated activity. Moreover, our data caution against excluding the N terminus and extracellular loops in structural studies of this 7 transmembrane receptor family.
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Affiliation(s)
- Arnauld Belmer
- Institut du Fer à Moulin, Université Pierre et Marie Curie, Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche S-839, Paris, France (A.B., S.D., V.S., S.M.B., I.M., K.B., L.M.); and Department of Pharmacology, School of Medicine, University of North Carolina, Chapel Hill, North Carolina (T.K.)
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Josep Agulleiro M, Cortés R, Fernández-Durán B, Navarro S, Guillot R, Meimaridou E, Clark AJL, Cerdá-Reverter JM. Melanocortin 4 receptor becomes an ACTH receptor by coexpression of melanocortin receptor accessory protein 2. Mol Endocrinol 2013; 27:1934-45. [PMID: 24085819 DOI: 10.1210/me.2013-1099] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Melanocortin 2 receptor (MC2R) is the only canonical ACTH receptor. Its functional expression requires the presence of an accessory protein, known as melanocortin receptor 2 accessory protein 1 (MRAP1). The vertebrate genome exhibits a paralogue gene called MRAP2, which is duplicated in zebrafish (MRAP2a and MRAP2b), although its function remains unknown. In this paper, we demonstrate that MRAP2a enables MC4R, a canonical MSH receptor, to be activated by ACTH with a similar sensitivity to that exhibited by MC2R. Both proteins physically interact and are coexpressed in the neurons of the preoptic area, a key region in the control of the energy balance and hypophyseal secretion in fish. ACTH injections inhibit food intake in wild-type zebrafish but not in fish lacking functional MC4R. Both MRAP1 and MRAP2a are hormonally regulated, suggesting that these proteins are substrates for feed-back regulatory pathways of melanocortin signaling. Fasting has no effect on the central expression of MRAP2a but stimulates MRAP2b expression. This protein interacts and is colocalized with MC4R in the tuberal hypothalamic neurons but has no effect on the pharmacologic profile of MC4R. However, MRPA2b is able to decrease basal reporter activity in cell lines expressing MC4R. It is plausible that MRAP2b decreases the constitutive activity of the MC4R during fasting periods, driving the animal toward a positive energy balance. Our data indicate that MRAP2s control the activity of MC4R, opening up new pathways for the regulation of melanocortin signaling and, by extension, for the regulation of the energy balance and obesity.
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Affiliation(s)
- Maria Josep Agulleiro
- Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, 12595 Torre de la Sal, Ribera de Cabanes, Castellón, Spain.
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Prömel S, Langenhan T, Araç D. Matching structure with function: the GAIN domain of adhesion-GPCR and PKD1-like proteins. Trends Pharmacol Sci 2013; 34:470-8. [PMID: 23850273 DOI: 10.1016/j.tips.2013.06.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2013] [Revised: 05/31/2013] [Accepted: 06/13/2013] [Indexed: 02/01/2023]
Abstract
Elucidation of structural information can greatly facilitate the understanding of molecular function. A recent example is the description of the G-protein-coupled receptor (GPCR) autoproteolysis-inducing (GAIN) domain, an evolutionarily ancient fold present in Adhesion-GPCRs (aGPCRs) and polycystic kidney disease 1 (PKD1)-like proteins. In the past, the peculiar autoproteolytic capacity of both membrane protein families at the conserved GPCR proteolysis site (GPS) had not been described in detail. The physiological performance of aGPCRs and PKD1-like proteins is thought to be regulated through the GPS, but it is debated how. A recent report provides pivotal details by discovery and analysis of the GAIN domain structure that incorporates the GPS motif. Complementary studies have commenced to analyze physiological requirements of the GAIN domain for aGPCR function, indicating that it serves as the linchpin for multiple receptor signals. Structural analysis and functional assays now allow for the dissection of the biological duties conferred through the GAIN domain.
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Affiliation(s)
- Simone Prömel
- Institute of Biochemistry, Molecular Biochemistry, Medical Faculty, University of Leipzig, Johannisallee 30, 04103 Leipzig, Germany
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Kay EI, Botha R, Montgomery JM, Mountjoy KG. hMRAPa increases αMSH-induced hMC1R and hMC3R functional coupling and hMC4R constitutive activity. J Mol Endocrinol 2013; 50:203-15. [PMID: 23296982 DOI: 10.1530/jme-12-0221] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Human melanocortin 2 receptor accessory protein (hMRAPa) is hypothesised to have functions beyond promoting human melanocortin 2 receptor (hMC2R) functional expression. To understand these potential functions, we exogenously co-expressed hMRAPa-FLAG with each of the five hMCR subtypes in HEK293 cells and assessed hMCR subtype coupling to adenylyl cyclase. We also co-expressed each HA-hMCR subtype with hMRAPa-FLAG to investigate their subcellular localisation. hMRAPa-FLAG enhanced α-melanocyte stimulating hormone (α-MSH)-stimulated hMC1R and hMC3R but reduced NDP-α-MSH-stimulated hMC5R, maximum coupling to adenylyl cyclase. hMRAPa-FLAG specifically increased hMC4R constitutive coupling to adenylyl cyclase despite not co-localising with the HA-hMC4R in the cell membrane. hMRAPa-FLAG co-localised with HA-hMC1R or HA-hMC3R in the perinuclear region, in cytoplasmic vesicles and at the plasma membrane, while it co-localised with HA-hMC2R, HA-hMC4R and HA-hMC5R predominantly in cytoplasmic vesicles. These diverse effects of hMRAPa indicate that hMRAPa could be an important modulator of the central and peripheral melanocortin systems if hMRAPa and any hMCR subtype co-express in the same cell.
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Affiliation(s)
- Emma I Kay
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1142, New Zealand
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