1
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Trotta RJ, Harmon DL, Klotz JL. Serotonin receptor-mediated vasorelaxation occurs primarily through 5-HT 4 activation in bovine lateral saphenous vein. Physiol Rep 2024; 12:e16128. [PMID: 38946059 PMCID: PMC11214916 DOI: 10.14814/phy2.16128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 05/15/2024] [Accepted: 06/20/2024] [Indexed: 07/02/2024] Open
Abstract
To better understand mechanisms of serotonin- (5-HT) mediated vasorelaxation, isolated lateral saphenous veins from cattle were assessed for vasoactivity using myography in response to increasing concentrations of 5-HT or selective 5-HT receptor agonists. Vessels were pre-contracted with 1 × 10-4 M phenylephrine and exposed to increasing concentrations of 5-HT or 5-HT receptor agonists that were selective for 5-HT1B, 5-HT2B, 5-HT4, and 5-HT7. Vasoactive response data were normalized as a percentage of the maximum contractile response induced by the phenylephrine pre-contraction. At 1 × 10-7 M 5-HT, a relaxation was observed with an 88.7% decrease (p < 0.01) from the phenylephrine maximum. At 1 × 10-4 M 5-HT, a contraction was observed with a 165% increase (p < 0.01) from the phenylephrine maximum. Increasing concentrations of agonists selective for 5-HT2B, 5-HT4, or 5-HT7 resulted in a 27%, 92%, or 44% (p < 0.01) decrease from the phenylephrine maximum, respectively. Of these 5-HT receptor agonists, the selective 5-HT4 receptor agonist resulted in the greatest potency (-log EC50) value (6.30) compared with 5-HT2B and 5-HT7 receptor agonists (4.21 and 4.66, respectively). To confirm the involvement of 5-HT4 in 5-HT-mediated vasorelaxation, blood vessels were exposed to either DMSO (solvent control) or a selective 5-HT4 antagonist (1 × 10-5 M) for 5-min prior to the phenylephrine pre-contraction and 5-HT additions. Antagonism of the 5-HT4 receptor attenuated the vasorelaxation caused by 5-HT. Approximately 94% of the vasorelaxation occurring in response to 5-HT could be accounted for through 5-HT4, providing strong evidence that 5-HT-mediated vasorelaxation occurs through 5-HT4 activation in bovine peripheral vasculature.
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Affiliation(s)
- Ronald J. Trotta
- Department of Animal and Food SciencesUniversity of KentuckyLexingtonKentuckyUSA
| | - David L. Harmon
- Department of Animal and Food SciencesUniversity of KentuckyLexingtonKentuckyUSA
| | - James L. Klotz
- Forage‐Animal Production Research UnitUSDA‐ARSLexingtonKentuckyUSA
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2
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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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3
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Wu Z, Han Z, Tao L, Sun X, Su J, Hu J, Li C. Dynamic Insights into the Self-Activation Pathway and Allosteric Regulation of the Orphan G-Protein-Coupled Receptor GPR52. J Chem Inf Model 2023; 63:5847-5862. [PMID: 37651308 DOI: 10.1021/acs.jcim.3c00672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
Within over 800 members of G-protein-coupled receptors, there are numerous orphan receptors whose endogenous ligands are largely unknown, providing many opportunities for novel drug discovery. However, the lack of an in-depth understanding of the intrinsic working mechanism for orphan receptors severely limits the related rational drug design. The G-protein-coupled receptor 52 (GPR52) is a unique orphan receptor that constitutively increases cellular 5'-cyclic adenosine monophosphate (cAMP) levels without binding any exogenous agonists and has been identified as a promising therapeutic target for central nervous system disorders. Although recent structural biology studies have provided snapshots of both active and inactive states of GPR52, the mechanism of the conformational transition between these states remains unclear. Here, an acceptable self-activation pathway for GPR52 was proposed through 6 μs Gaussian accelerated molecular dynamics (GaMD) simulations, in which the receptor spontaneously transitions from the active state to that matching the inactive crystal structure. According to the three intermediate states of the receptor obtained by constructing a reweighted potential of mean force, how the allosteric regulation occurs between the extracellular orthosteric binding pocket and the intracellular G-protein-binding site is revealed. Combined with the independent gradient model, several important microswitch residues and the allosteric communication pathway that directly links the two regions are both identified. Transfer entropy calculations not only reveal the complex allosteric signaling within GPR52 but also confirm the unique role of ECL2 in allosteric regulation, which is mutually validated with the results of GaMD simulations. Overall, this work elucidates the allosteric mechanism of GPR52 at the atomic level, providing the most detailed information to date on the self-activation of the orphan receptor.
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Affiliation(s)
- Zhixiang Wu
- Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing 100124, China
| | - Zhongjie Han
- Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing 100124, China
| | - Lianci Tao
- Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing 100124, China
| | - Xiaohan Sun
- Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing 100124, China
| | - Jingjie Su
- Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing 100124, China
| | - Jianping Hu
- Key Laboratory of Medicinal and Edible Plants Resources Development of Sichuan Education Department, School of Pharmacy, Chengdu University, Chengdu 610106, China
| | - Chunhua Li
- Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing 100124, China
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4
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Belinskaia DA, Voronina PA, Krivorotov DV, Jenkins RO, Goncharov NV. Anticholinesterase and Serotoninergic Evaluation of Benzimidazole-Carboxamides as Potential Multifunctional Agents for the Treatment of Alzheimer's Disease. Pharmaceutics 2023; 15:2159. [PMID: 37631373 PMCID: PMC10459044 DOI: 10.3390/pharmaceutics15082159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 08/15/2023] [Accepted: 08/17/2023] [Indexed: 08/27/2023] Open
Abstract
The etiology and pathogenesis of Alzheimer's disease are multifactorial, so one of the treatment strategies is the development of the drugs that affect several targets associated with the pathogenesis of the disease. Within this roadmap, we investigated the interaction of several substituted 1,3-dihydro-2-oxo-1H-benzimidazol-2-ones with their potential molecular targets: cholinesterases (ChE) and three types of the Gs-protein-coupled serotonin receptors (5-HTR) 5-HT6, 5-HT4 and 5-HT7 (5-HT4R, 5-HT6R and 5-HT7R, respectively). A microplate modification of the Ellman method was used for the biochemical analysis of the inhibitory ability of the drugs towards ChE. Molecular modeling methods, such as molecular docking and molecular dynamics (MD) simulation in water and the lipid bilayer, were used to study the interaction of the compounds with ChE and 5-HTR. In vitro experiments showed that the tested compounds had moderate anticholinesterase activity. With the help of molecular modeling methods, the mechanism of interaction of the tested compounds with ChE was investigated, the binding sites were described and the structural features of the drugs that determine the strength of their anticholinesterase activity were revealed. Primary in silico evaluation showed that benzimidazole-carboxamides effectively bind to 5-HT4R and 5-HT7R. The pool of the obtained data allows us to choose N-[2-(diethylamino)ethyl]-2-oxo-3-(tert-butyl)-2,3-dihydro-1H-benzimidazole-1-carboxamide hydrochloride (compound 13) as the most promising for further experimental development.
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Affiliation(s)
- Daria A. Belinskaia
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Thorez 44, St. Petersburg 194223, Russia
| | - Polina A. Voronina
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Thorez 44, St. Petersburg 194223, Russia
| | - Denis V. Krivorotov
- Research Institute of Hygiene, Occupational Pathology and Human Ecology, Federal Medical Biological Agency, p.o. Kuzmolovsky, St. Petersburg 188663, Russia
| | - Richard O. Jenkins
- Leicester School of Allied Health Sciences, De Montfort University, The Gateway, Leicester LE1 9BH, UK
| | - Nikolay V. Goncharov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Thorez 44, St. Petersburg 194223, Russia
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5
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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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6
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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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7
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Pujol CN, Dupuy V, Séveno M, Runtz L, Bockaert J, Marin P, Chaumont-Dubel S. Dynamic interactions of the 5-HT 6 receptor with protein partners control dendritic tree morphogenesis. Sci Signal 2020; 13:13/618/eaax9520. [PMID: 32047117 DOI: 10.1126/scisignal.aax9520] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The serotonin (5-hydroxytrypatmine) receptor 5-HT6 (5-HT6R) has emerged as a promising target to alleviate the cognitive symptoms of neurodevelopmental diseases. We previously demonstrated that 5-HT6R finely controls key neurodevelopmental steps, including neuronal migration and the initiation of neurite growth, through its interaction with cyclin-dependent kinase 5 (Cdk5). Here, we showed that 5-HT6R recruited G protein-regulated inducer of neurite outgrowth 1 (GPRIN1) through a Gs-dependent mechanism. Interactions between the receptor and either Cdk5 or GPRIN1 occurred sequentially during neuronal differentiation. The 5-HT6R-GPRIN1 interaction enhanced agonist-independent, receptor-stimulated cAMP production without altering the agonist-dependent response in NG108-15 neuroblastoma cells. This interaction also promoted neurite extension and branching in NG108-15 cells and primary mouse striatal neurons through a cAMP-dependent protein kinase A (PKA)-dependent mechanism. This study highlights the complex allosteric modulation of GPCRs by protein partners and demonstrates how dynamic interactions between GPCRs and their protein partners can control the different steps of highly coordinated cellular processes, such as dendritic tree morphogenesis.
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Affiliation(s)
- Camille N Pujol
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Vincent Dupuy
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Martial Séveno
- BioCampus Montpellier, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Leonie Runtz
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France.,Department of Psychiatry, McGill University, Douglas Hospital Research Center, Montreal, Canada
| | - Joël Bockaert
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Philippe Marin
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France.
| | - Séverine Chaumont-Dubel
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France.
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8
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Pérez-Benito L, Llinas del Torrent C, Pardo L, Tresadern G. The computational modeling of allosteric modulation of metabotropic glutamate receptors. FROM STRUCTURE TO CLINICAL DEVELOPMENT: ALLOSTERIC MODULATION OF G PROTEIN-COUPLED RECEPTORS 2020; 88:1-33. [DOI: 10.1016/bs.apha.2020.02.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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9
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Della Longa S, Arcovito A. Microswitches for the Activation of the Nociceptin Receptor Induced by Cebranopadol: Hints from Microsecond Molecular Dynamics. J Chem Inf Model 2019; 59:818-831. [PMID: 30640458 DOI: 10.1021/acs.jcim.8b00759] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cebranopadol (CBP) is a novel analgesic acting as agonist at the nociceptin (NOP) and μ-opioid (MOP) receptors, exhibiting high potency and efficacy as an antinociceptive and antihypersensitive drug. The binding conformation and the dynamical interactions of CBP with the NOP receptor have been investigated by molecular docking, molecular dynamics (MD) in the microsecond time scale, and hybrid quantum mechanics/molecular mechanics (QM/MM). CBP binds to the NOP receptor as a bidentate ligand of the aspartate D1303,32 by means of both its fluoroindole and dimethyl nitrogens. Starting from the known crystal structure of the inactive state of the receptor, in complex with the antagonist compound-24 (NOP-C24) the comparative analysis of 1 μs MD trajectories of the NOP-C24 complex itself and the NOP_free and NOP-CBP complexes provides new insights on the already known microswitches related to receptor activation, in the frame of the extended ternary complex model. The agonist acts by destabilizing the inactive conformation of the NOP receptor, by inducing a conformational change of M1343,36, which allows W2766,48 to flip around its χ2 dihedral, going in close proximity to the receptor hydrophobic core (T1383,40, P2275,50, F2726,44), which is known to be fundamental for the activation of the opioid receptors. A complete rational picture is also provided for the role of N1333,35 and W2766,48 undergoing critical conformational changes related to an anticooperativity effect, i.e. the well-known role of sodium as negative modulator of agonist binding. Finally, the movement of residue Y3197,53 belonging to the NPxxY motif is also induced by the binding of the agonist in the inactive state, opening a gate for a water channel just as upon receptor activation.
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Affiliation(s)
- Stefano Della Longa
- Department of Life, Health and Environmental Sciences , University of L'Aquila , L'Aquila , 67100 Italy
| | - Alessandro Arcovito
- Istituto di Biochimica e Biochimica Clinica , Università Cattolica del Sacro Cuore , Rome , 00168 Italy.,Fondazione Policlinico Universitario A. Gemelli - IRCCS, Rome , 00168 Italy
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10
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Vass M, Podlewska S, de Esch IJP, Bojarski AJ, Leurs R, Kooistra AJ, de Graaf C. Aminergic GPCR-Ligand Interactions: A Chemical and Structural Map of Receptor Mutation Data. J Med Chem 2018; 62:3784-3839. [PMID: 30351004 DOI: 10.1021/acs.jmedchem.8b00836] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The aminergic family of G protein-coupled receptors (GPCRs) plays an important role in various diseases and represents a major drug discovery target class. Structure determination of all major aminergic subfamilies has enabled structure-based ligand design for these receptors. Site-directed mutagenesis data provides an invaluable complementary source of information for elucidating the structural determinants of binding of different ligand chemotypes. The current study provides a comparative analysis of 6692 mutation data points on 34 aminergic GPCR subtypes, covering the chemical space of 540 unique ligands from mutagenesis experiments and information from experimentally determined structures of 52 distinct aminergic receptor-ligand complexes. The integrated analysis enables detailed investigation of structural receptor-ligand interactions and assessment of the transferability of combined binding mode and mutation data across ligand chemotypes and receptor subtypes. An overview is provided of the possibilities and limitations of using mutation data to guide the design of novel aminergic receptor ligands.
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Affiliation(s)
- Márton Vass
- Division of Medicinal Chemistry, Faculty of Sciences, Amsterdam Institute for Molecules, Medicines and Systems (AIMMS) , VU University Amsterdam , 1081HZ Amsterdam , The Netherlands
| | - Sabina Podlewska
- Department of Medicinal Chemistry, Institute of Pharmacology , Polish Academy of Sciences , Smętna 12 , PL31-343 Kraków , Poland
| | - Iwan J P de Esch
- Division of Medicinal Chemistry, Faculty of Sciences, Amsterdam Institute for Molecules, Medicines and Systems (AIMMS) , VU University Amsterdam , 1081HZ Amsterdam , The Netherlands
| | - Andrzej J Bojarski
- Department of Medicinal Chemistry, Institute of Pharmacology , Polish Academy of Sciences , Smętna 12 , PL31-343 Kraków , Poland
| | - Rob Leurs
- Division of Medicinal Chemistry, Faculty of Sciences, Amsterdam Institute for Molecules, Medicines and Systems (AIMMS) , VU University Amsterdam , 1081HZ Amsterdam , The Netherlands
| | - Albert J Kooistra
- Division of Medicinal Chemistry, Faculty of Sciences, Amsterdam Institute for Molecules, Medicines and Systems (AIMMS) , VU University Amsterdam , 1081HZ Amsterdam , The Netherlands.,Department of Drug Design and Pharmacology , University of Copenhagen , Universitetsparken 2 , 2100 Copenhagen , Denmark
| | - Chris de Graaf
- Division of Medicinal Chemistry, Faculty of Sciences, Amsterdam Institute for Molecules, Medicines and Systems (AIMMS) , VU University Amsterdam , 1081HZ Amsterdam , The Netherlands.,Sosei Heptares , Steinmetz Building, Granta Park, Great Abington , Cambridge CB21 6DG , U.K
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11
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12
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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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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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Rodríguez-Espigares I, Kaczor AA, Selent J. In silico Exploration of the Conformational Universe of GPCRs. Mol Inform 2016; 35:227-37. [PMID: 27492237 DOI: 10.1002/minf.201600012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 04/14/2016] [Indexed: 12/17/2022]
Abstract
The structural plasticity of G protein coupled receptors (GPCRs) leads to a conformational universe going from inactive to active receptor states with several intermediate states. Many of them have not been captured yet and their role for GPCR activation is not well understood. The study of this conformational space and the transition dynamics between different receptor populations is a major challenge in molecular biophysics. The rational design of effector molecules that target such receptor populations allows fine-tuning receptor signalling with higher specificity to produce drugs with safer therapeutic profiles. In this minireview, we outline highly conserved receptor regions which are considered determinant for the establishment of distinct receptor states. We then discuss in-silico approaches such as dimensionality reduction methods and Markov State Models to explore the GPCR conformational universe and exploit the obtained conformations through structure-based drug design.
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Affiliation(s)
- Ismael Rodríguez-Espigares
- Pharmacoinformatics group, Research Programme on Biomedical Informatics (GRIB), Universitat Pompeu Fabra (UPF)-Hospital del Mar Medical Research Institute (IMIM), Parc de Recerca Biomèdica de Barcelona (PRBB), Dr. Aiguader, 88, 08003, Barcelona, Spain
| | - Agnieszka A Kaczor
- Department of Synthesis and Chemical Technology of Pharmaceutical Substances with Computer Modeling Lab, Faculty of Pharmacy with Division for Medical Analytics, Medical University of Lublin, 4A Chodźki St., PL-20059, Lublin, Poland.,School of Pharmacy, University of Eastern Finland, Yliopistonranta 1, P.O. Box 1627, FI-70211, Kuopio, Finland
| | - Jana Selent
- Pharmacoinformatics group, Research Programme on Biomedical Informatics (GRIB), Universitat Pompeu Fabra (UPF)-Hospital del Mar Medical Research Institute (IMIM), Parc de Recerca Biomèdica de Barcelona (PRBB), Dr. Aiguader, 88, 08003, Barcelona, Spain.
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15
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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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Stoddart LA, Kellam B, Briddon SJ, Hill SJ. Effect of a toggle switch mutation in TM6 of the human adenosine A₃ receptor on Gi protein-dependent signalling and Gi-independent receptor internalization. Br J Pharmacol 2015; 171:3827-44. [PMID: 24750014 PMCID: PMC4128046 DOI: 10.1111/bph.12739] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 04/07/2014] [Accepted: 04/14/2014] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND AND PURPOSE The highly conserved tryptophan (W6.48) in transmembrane domain 6 of GPCRs has been shown to play a central role in forming an active conformation in response to agonist binding. We set out to characterize the effect of this mutation on the efficacy of two agonists at multiple signalling pathways downstream of the adenosine A3 receptor. EXPERIMENTAL APPROACH Residue W6.48 in the human adenosine A3 receptor fused to yellow fluorescent protein was mutated to phenylalanine and expressed in CHO-K1 cells containing a cAMP response element reporter gene. The effects on agonist-mediated receptor internalization were monitored by automated confocal microscopy and image analysis. Further experiments were carried out to investigate agonist-mediated ERK1/2 phosphorylation, inhibition of [3H]-cAMP accumulation and β-arrestin2 binding. KEY RESULTS NECA was able to stimulate agonist-mediated internalization of the W6.48F mutant receptor, while the agonist HEMADO was inactive. Investigation of other downstream signalling pathways indicated that G-protein coupling was impaired for both agonists tested. Mutation of W6.48F therefore resulted in differential effects on agonist efficacy, and introduced signalling pathway bias for HEMADO at the adenosine A3 receptor. CONCLUSIONS AND IMPLICATIONS Investigation of the pharmacology of the W6.48F mutant of the adenosine A3 receptor confirms that this region is important in forming the active conformation of the receptor for stimulating a number of different signalling pathways and that mutations in this residue can lead to changes in agonist efficacy and signalling bias.
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Affiliation(s)
- Leigh A Stoddart
- Institute of Cell Signalling, School of Life Sciences, The University of Nottingham, Nottingham, UK
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Bertheleme N, Singh S, Dowell SJ, Hubbard J, Byrne B. Loss of constitutive activity is correlated with increased thermostability of the human adenosine A2A receptor. Br J Pharmacol 2015; 169:988-98. [PMID: 23489072 DOI: 10.1111/bph.12165] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 02/12/2013] [Accepted: 02/19/2013] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND AND PURPOSE Thermostabilization by mutagenesis is one method which has facilitated the determination of high-resolution structures of the adenosine A2A receptor (A(2A)R). Sets of mutations were identified, which both thermostabilized the receptor and resulted in preferential agonist (Rag23 mutant) or antagonist (Rant5 and Rant21) binding forms as assessed by radioligand binding analysis. While the ligand-binding profiles of these mutants are known, the effects these mutations have on receptor activation and downstream signalling are less well characterized. EXPERIMENTAL APPROACH Here we have investigated the effects of the thermostabilizing mutations on receptor activation using a yeast cell growth assay. The assay employs an engineered Saccharomyces cerevisiae, MMY24, which couples receptor activation to cell growth. KEY RESULTS Analysis of the receptor activation profile revealed that the wild-type (WT) A(2A)R had considerable constitutive activity. In contrast, the Rag23, Rant5 and Rant21 thermostabilized mutants all exhibited no constitutive activity. While the preferentially antagonist-binding mutants Rant5 and Rant21 showed a complete lack of agonist-induced activity, the Rag23 mutant showed high levels of agonist-induced receptor activity. Further analysis using a mutant intermediate between Rag23 and WT indicated that the loss of constitutive activity observed in the agonist responsive mutants was not due to reduced G-protein coupling. CONCLUSIONS AND IMPLICATIONS The loss of constitutive activity may be an important feature of these thermostabilized GPCRs. In addition, the constitutively active and agonist-induced active conformations of the A(2A)R are distinct.
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Xie L, Ge X, Tan H, Xie L, Zhang Y, Hart T, Yang X, Bourne PE. Towards structural systems pharmacology to study complex diseases and personalized medicine. PLoS Comput Biol 2014; 10:e1003554. [PMID: 24830652 PMCID: PMC4022462 DOI: 10.1371/journal.pcbi.1003554] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Genome-Wide Association Studies (GWAS), whole genome sequencing, and high-throughput omics techniques have generated vast amounts of genotypic and molecular phenotypic data. However, these data have not yet been fully explored to improve the effectiveness and efficiency of drug discovery, which continues along a one-drug-one-target-one-disease paradigm. As a partial consequence, both the cost to launch a new drug and the attrition rate are increasing. Systems pharmacology and pharmacogenomics are emerging to exploit the available data and potentially reverse this trend, but, as we argue here, more is needed. To understand the impact of genetic, epigenetic, and environmental factors on drug action, we must study the structural energetics and dynamics of molecular interactions in the context of the whole human genome and interactome. Such an approach requires an integrative modeling framework for drug action that leverages advances in data-driven statistical modeling and mechanism-based multiscale modeling and transforms heterogeneous data from GWAS, high-throughput sequencing, structural genomics, functional genomics, and chemical genomics into unified knowledge. This is not a small task, but, as reviewed here, progress is being made towards the final goal of personalized medicines for the treatment of complex diseases.
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Affiliation(s)
- Lei Xie
- Department of Computer Science, Hunter College, The City University of New York, New York, New York, United States of America
- Ph.D. Program in Computer Science, Biology, and Biochemistry, The Graduate Center, The City University of New York, New York, New York, United States of America
- * E-mail:
| | - Xiaoxia Ge
- Department of Computer Science, Hunter College, The City University of New York, New York, New York, United States of America
| | - Hepan Tan
- Department of Computer Science, Hunter College, The City University of New York, New York, New York, United States of America
| | - Li Xie
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, United States of America
| | - Yinliang Zhang
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, United States of America
| | - Thomas Hart
- Department of Biological Sciences, Hunter College, The City University of New York, New York, New York, United States of America
| | - Xiaowei Yang
- School of Public Health, Hunter College, The City University of New York, New York, New York, United States of America
| | - Philip E. Bourne
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, United States of America
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Dalton JAR, Gómez-Santacana X, Llebaria A, Giraldo J. Computational analysis of negative and positive allosteric modulator binding and function in metabotropic glutamate receptor 5 (in)activation. J Chem Inf Model 2014; 54:1476-87. [PMID: 24793143 DOI: 10.1021/ci500127c] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Metabotropic glutamate receptors (mGluRs) are high-profile G-protein coupled receptors drug targets because of their involvement in several neurological disease states, and mGluR5 in particular is a subtype whose controlled allosteric modulation, both positive and negative, can potentially be useful for the treatment of schizophrenia and relief of chronic pain, respectively. Here we model mGluR5 with a collection of positive and negative allosteric modulators (PAMs and NAMs) in both active and inactive receptor states, in a manner that is consistent with experimental information, using a specialized protocol that includes homology to increase docking accuracy, and receptor relaxation to generate an individual induced fit with each allosteric modulator. Results implicate two residues in particular for NAM and PAM function: NAM interaction with W785 for receptor inactivation, and NAM/PAM H-bonding with S809 for receptor (in)activation. Models suggest the orientation of the H-bond between allosteric modulator and S809, controlled by PAM/NAM chemistry, influences the position of TM7, which in turn influences the shape of the allosteric site, and potentially the receptor state. NAM-bound and PAM-bound mGluR5 models also reveal that although PAMs and NAMs bind in the same pocket and share similar binding modes, they have distinct effects on the conformation of the receptor. Our models, together with the identification of a possible activation mechanism, may be useful in the rational design of new allosteric modulators for mGluR5.
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Affiliation(s)
- James A R Dalton
- Laboratory of Molecular Neuropharmacology and Bioinformatics, Institut de Neurociències and Unitat de Bioestadística, Universitat Autònoma de Barcelona , 08193 Bellaterra, Barcelona, Spain
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Insights into the influence of 5-HT2c aminoacidic variants with the inhibitory action of serotonin inverse agonists and antagonists. J Mol Model 2014; 20:2120. [PMID: 24562856 DOI: 10.1007/s00894-014-2120-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Accepted: 12/15/2013] [Indexed: 12/13/2022]
Abstract
Specific modulation of serotonin 5-HT(2C) G protein-coupled receptors may be therapeutic for obesity and neuropsychiatric disorders. The different efficacy of drugs targeting these receptors are due to the presence of genetic variants in population and this variability is still hard to predict. Therefore, in order to administer the more suitable drug, taking into account patient genotype, it is necessary to know the molecular effects of its gene nucleotide variations. In this work, starting from an accurate 3D model of 5-HT(2C), we focus on the prediction of the possible effect of some single nucleotide polymorphisms (SNPs) producing amino acidic changes in proximity of the 5-HT(2C) ligand binding site. Particularly we chose a set of 5-HT(2C) inverse agonists and antagonists which have high inhibitory activity. After prediction of the structures of the receptor-ligand complexes using molecular docking tools, we performed full atom molecular dynamics simulations in explicit lipid bilayer monitoring the interactions between ligands and trans-membrane helices of the receptor, trying to infer relations with their biological activity. Serotonin, as the natural ligand was chosen as reference compound to advance a hypothesis able to explain the receptor inhibition mechanism. Indeed we observed a different behavior between the antagonists and inverse agonist with respect to serotonin or unbounded receptor, which could be responsible, even if not directly, of receptor's inactivation. Furthermore, we analyzed five aminoacidic variants of 5HT(2C) receptor observing alterations in the interactions between ligands and receptor which give rise to changes of free energy values for every complex considered.
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Sheftel S, Muratore KE, Black M, Costanzi S. Graph analysis of β2 adrenergic receptor structures: a "social network" of GPCR residues. In Silico Pharmacol 2013; 1:16. [PMID: 25505660 PMCID: PMC4230308 DOI: 10.1186/2193-9616-1-16] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 11/25/2013] [Indexed: 02/07/2023] Open
Abstract
Purpose G protein-coupled receptors (GPCRs) are a superfamily of membrane proteins of vast pharmaceutical interest. Here, we describe a graph theory-based analysis of the structure of the β2 adrenergic receptor (β2 AR), a prototypical GPCR. In particular, we illustrate the network of direct and indirect interactions that link each amino acid residue to any other residue of the receptor. Methods Networks of interconnected amino acid residues in proteins are analogous to social networks of interconnected people. Hence, they can be studied through the same analysis tools typically employed to analyze social networks – or networks in general – to reveal patterns of connectivity, influential members, and dynamicity. We focused on the analysis of closeness-centrality, which is a measure of the overall connectivity distance of the member of a network to all other members. Results The residues endowed with the highest closeness-centrality are located in the middle of the seven transmembrane domains (TMs). In particular, they are mostly located in the middle of TM2, TM3, TM6 or TM7, while fewer of them are located in the middle of TM1, TM4 or TM5. At the cytosolic end of TM6, the centrality detected for the active structure is markedly lower than that detected for the corresponding residues in the inactive structures. Moreover, several residues acquire centrality when the structures are analyzed in the presence of ligands. Strikingly, there is little overlap between the residues that acquire centrality in the presence of the ligand in the blocker-bound structures and the agonist-bound structures. Conclusions Our results reflect the fact that the receptor resembles a bow tie, with a rather tight knot of closely interconnected residues and two ends that fan out in two opposite directions: one toward the extracellular space, which hosts the ligand binding cavity, and one toward the cytosol, which hosts the G protein binding cavity. Moreover, they underscore how interaction network is by the conformational rearrangements concomitant with the activation of the receptor and by the presence of agonists or blockers. Electronic supplementary material The online version of this article (doi:10.1186/2193-9616-1-16) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Samuel Sheftel
- Department of Chemistry, American University, 4400 Massachusetts Ave, Northwest, Washington, DC 20016 USA
| | - Kathryn E Muratore
- Department of Chemistry, American University, 4400 Massachusetts Ave, Northwest, Washington, DC 20016 USA
| | - Michael Black
- Department of Computer Science, American University, Northwest, Washington, DC 20016 USA
| | - Stefano Costanzi
- Department of Chemistry, American University, 4400 Massachusetts Ave, Northwest, Washington, DC 20016 USA ; Center for Behavioral Neuroscience, American University, Northwest, Washington, DC 20016 USA
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Olivella M, Caltabiano G, Cordomí A. The role of Cysteine 6.47 in class A GPCRs. BMC STRUCTURAL BIOLOGY 2013; 13:3. [PMID: 23497259 PMCID: PMC3610275 DOI: 10.1186/1472-6807-13-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 03/06/2013] [Indexed: 11/10/2022]
Abstract
Background The CWxP motif of transmembrane helix 6 (x: any residue) is highly conserved in class A GPCRs. Within this motif, W6.48 is a big star in the theory of the global “toggle switch” because of its key role in the activation mechanism of GPCRs upon ligand binding. With all footlights focused on W6.48, the reason why the preceding residue, C6.47, is largely conserved is still unknown. The present study is aimed to fill up this lack of knowledge by characterizing the role of C6.47 of the CWxP motif. Results A complete analysis of available crystal structures has been made alongside with molecular dynamics simulations of model peptides to explore a possible structural role for C6.47. Conclusions We conclude that C6.47 does not modulate the conformation of the TM6 proline kink and propose that C6.47 participates in the rearrangement of the TM6 and TM7 interface accompanying activation.
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Affiliation(s)
- Mireia Olivella
- Departament de Biologia de Sistemes, Universitat de Vic, Vic, Barcelona 08500, Catalonia
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23
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Steen A, Thiele S, Guo D, Hansen LS, Frimurer TM, Rosenkilde MM. Biased and constitutive signaling in the CC-chemokine receptor CCR5 by manipulating the interface between transmembrane helices 6 and 7. J Biol Chem 2013; 288:12511-21. [PMID: 23493400 DOI: 10.1074/jbc.m112.449587] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The equilibrium state of CCR5 is manipulated here toward either activation or inactivation by introduction of single amino acid substitutions in the transmembrane domains (TMs) 6 and 7. Insertion of a steric hindrance mutation in the center of TM7 (G286F in position VII:09/7.42) resulted in biased signaling. Thus, β-arrestin recruitment was eliminated, whereas constitutive activity was observed in Gαi-mediated signaling. Furthermore, the CCR5 antagonist aplaviroc was converted to a full agonist (a so-called efficacy switch). Computational modeling revealed that the position of the 7TM receptor-conserved Trp in TM6 (Trp-248 in position VI:13/6.48, part of the CWXP motif) was influenced by the G286F mutation, causing Trp-248 to change orientation away from TM7. The essential role of Trp-248 in CCR5 activation was supported by complete inactivity of W248A-CCR5 despite maintaining chemokine binding. Furthermore, replacing Trp-248 with a smaller aromatic amino acid (Tyr/Phe) impaired the β-arrestin recruitment, yet with maintained G protein activity (biased signaling); also, here aplaviroc switched to a full agonist. Thus, the altered positioning of Trp-248, induced by G286F, led to a constraint of G protein active, but β-arrestin inactive and thus biased, CCR5 conformation. These results provide important information on the molecular interplay and impact of TM6 and TM7 for CCR5 activity, which may be extrapolated to other chemokine receptors and possibly to other 7TM receptors.
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Affiliation(s)
- Anne Steen
- Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, The Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen, Denmark
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Kenakin T. New concepts in pharmacological efficacy at 7TM receptors: IUPHAR review 2. Br J Pharmacol 2013; 168:554-75. [PMID: 22994528 PMCID: PMC3579279 DOI: 10.1111/j.1476-5381.2012.02223.x] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 08/03/2012] [Accepted: 09/12/2012] [Indexed: 01/14/2023] Open
Abstract
The present-day concept of drug efficacy has changed completely from its original description as the property of agonists that causes tissue activation. The ability to visualize the multiple behaviours of seven transmembrane receptors has shown that drugs can have many efficacies and also that the transduction of drug stimulus to various cellular stimulus-response cascades can be biased towards some but not all pathways. This latter effect leads to agonist 'functional selectivity', which can be favourable for the improvement of agonist therapeutics. However, in addition, biased agonist potency becomes cell type dependent with the loss of the monotonic behaviour of stimulus-response mechanisms, leading to potential problems in agonist quantification. This has an extremely important effect on the discovery process for new agonists since it now cannot be assumed that a given screening or lead optimization assay will correctly predict therapeutic behaviour. This review discusses these ideas and how new approaches to quantifying agonist effect may be used to circumvent the cell type dependence of agonism. This article, written by a corresponding member of the International Union of Basic and Clinical Pharmacology Committee on Receptor Nomenclature and Drug Classification (NC-IUPHAR), reviews our current understanding of the interaction of ligands with seven transmembrane receptors. Further information on these pharmacological concepts is being incorporated into the IUPHAR/BPS database GuideToPharmacology.org.
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Affiliation(s)
- Terry Kenakin
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC, USA.
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25
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Cochet M, Donneger R, Cassier E, Gaven F, Lichtenthaler SF, Marin P, Bockaert J, Dumuis A, Claeysen S. 5-HT4 receptors constitutively promote the non-amyloidogenic pathway of APP cleavage and interact with ADAM10. ACS Chem Neurosci 2013; 4:130-40. [PMID: 23336052 DOI: 10.1021/cn300095t] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 10/13/2012] [Indexed: 12/18/2022] Open
Abstract
In addition to the amyloidogenic pathway, amyloid precursor protein (APP) can be cleaved by α-secretases, producing soluble and neuroprotective APP alpha (sAPPα) (nonamyloidogenic pathway) and thus preventing the generation of pathogenic amyloid-β. However, the mechanisms regulating APP cleavage by α-secretases remain poorly understood. Here, we showed that expression of serotonin type 4 receptors (5-HT(4)Rs) constitutively (without agonist stimulation) induced APP cleavage by the α-secretase ADAM10 and the release of neuroprotective sAPPα in HEK-293 cells and cortical neurons. This effect was independent of cAMP production. Interestingly, we demonstrated that 5-HT(4) receptors physically interacted with the mature form of ADAM10. Stimulation of 5-HT(4) receptors by an agonist further increased sAPPα secretion, and this effect was mediated by cAMP/Epac signaling. These findings describe a new mechanism whereby a GPCR constitutively stimulates the cleavage of APP by α-secretase and promotes the nonamyloidogenic pathway of APP processing.
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Affiliation(s)
- Maud Cochet
- CNRS, UMR-5203,
Institut de Génomique Fonctionnelle, F-34000 Montpellier,
France
- Inserm, U661, F-34000 Montpellier, France
- Universités de Montpellier 1 & 2, UMR-5203, F-34000 Montpellier, France
| | - Romain Donneger
- CNRS, UMR-5203,
Institut de Génomique Fonctionnelle, F-34000 Montpellier,
France
- Inserm, U661, F-34000 Montpellier, France
- Universités de Montpellier 1 & 2, UMR-5203, F-34000 Montpellier, France
| | - Elisabeth Cassier
- CNRS, UMR-5203,
Institut de Génomique Fonctionnelle, F-34000 Montpellier,
France
- Inserm, U661, F-34000 Montpellier, France
- Universités de Montpellier 1 & 2, UMR-5203, F-34000 Montpellier, France
| | - Florence Gaven
- Inserm, U661, F-34000 Montpellier, France
- Universités de Montpellier 1 & 2, UMR-5203, F-34000 Montpellier, France
| | | | - Philippe Marin
- CNRS, UMR-5203,
Institut de Génomique Fonctionnelle, F-34000 Montpellier,
France
- Inserm, U661, F-34000 Montpellier, France
- Universités de Montpellier 1 & 2, UMR-5203, F-34000 Montpellier, France
| | - Joël Bockaert
- CNRS, UMR-5203,
Institut de Génomique Fonctionnelle, F-34000 Montpellier,
France
- Inserm, U661, F-34000 Montpellier, France
- Universités de Montpellier 1 & 2, UMR-5203, F-34000 Montpellier, France
| | - Aline Dumuis
- CNRS, UMR-5203,
Institut de Génomique Fonctionnelle, F-34000 Montpellier,
France
- Inserm, U661, F-34000 Montpellier, France
- Universités de Montpellier 1 & 2, UMR-5203, F-34000 Montpellier, France
| | - Sylvie Claeysen
- CNRS, UMR-5203,
Institut de Génomique Fonctionnelle, F-34000 Montpellier,
France
- Inserm, U661, F-34000 Montpellier, France
- Universités de Montpellier 1 & 2, UMR-5203, F-34000 Montpellier, France
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Abrol R, Kim SK, Bray JK, Trzaskowski B, Goddard WA. Conformational Ensemble View of G Protein-Coupled Receptors and the Effect of Mutations and Ligand Binding. Methods Enzymol 2013; 520:31-48. [DOI: 10.1016/b978-0-12-391861-1.00002-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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27
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Caltabiano G, Gonzalez A, Cordomí A, Campillo M, Pardo L. The Role of Hydrophobic Amino Acids in the Structure and Function of the Rhodopsin Family of G Protein-Coupled Receptors. Methods Enzymol 2013; 520:99-115. [DOI: 10.1016/b978-0-12-391861-1.00005-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
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28
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Gaven F, Pellissier LP, Queffeulou E, Cochet M, Bockaert J, Dumuis A, Claeysen S. Pharmacological profile of engineered 5-HT₄ receptors and identification of 5-HT₄ receptor-biased ligands. Brain Res 2012; 1511:65-72. [PMID: 23148949 DOI: 10.1016/j.brainres.2012.11.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Revised: 11/02/2012] [Accepted: 11/05/2012] [Indexed: 11/19/2022]
Abstract
G protein-coupled receptors (GPCRs) can activate simultaneously multiple signaling pathways upon agonist binding. The combined use of engineered GPCRs, such as the receptors activated solely by synthetic ligands (RASSLs), and of biased ligands that activate only one pathway at a time might help deciphering the physiological role of each G protein signaling. In order to find serotonin type 4 receptor (5-HT₄R) biased ligands, we analyzed the ability of several compounds to activate the Gs and G(q/11) pathways in COS-7 cells that transiently express wild type 5-HT₄R, the 5-HT₄R-D(100)A mutant (known also as 5-HT₄-RASSL, or Rs1) or the 5-HT₄R-T(104)A mutant, which modifies agonist-induced 5-HT₄R activation. This analysis allowed completing the pharmacological profile of the two mutant 5-HT₄Rs, but we did not find any biased ligand for the mutant receptors. Conversely, we identified the first biased agonists for wild type 5-HT₄R. Indeed, RS 67333 and prucalopride acted as partial agonists to induce cAMP accumulation, but as antagonists on inositol phosphate production. Moreover, they showed very different antagonist potencies that could be exploited to study the activation of the G(s) pathway, with or without concomitant block of G(q/11) signaling. This article is part of a Special Issue entitled Optogenetics (7th BRES).
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Affiliation(s)
- Florence Gaven
- CNRS, UMR-5203, Institut de Génomique Fonctionnelle, F-34000 Montpellier, France
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29
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Ersoy BA, Pardo L, Zhang S, Thompson DA, Millhauser G, Govaerts C, Vaisse C. Mechanism of N-terminal modulation of activity at the melanocortin-4 receptor GPCR. Nat Chem Biol 2012; 8:725-30. [PMID: 22729149 PMCID: PMC3657613 DOI: 10.1038/nchembio.1008] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Accepted: 05/14/2012] [Indexed: 01/29/2023]
Abstract
Most of our understanding of G protein-coupled receptor (GPCR) activation has been focused on the direct interaction between diffusible ligands and their seven-transmembrane domains. However, a number of these receptors depend on their extracellular N-terminal domain for ligand recognition and activation. To dissect the molecular interactions underlying both modes of activation at a single receptor, we used the unique properties of the melanocortin-4 receptor (MC4R), a GPCR that shows constitutive activity maintained by its N-terminal domain and is physiologically activated by the peptide α-melanocyte stimulating hormone (αMSH). We find that activation by the N-terminal domain and αMSH relies on different key residues in the transmembrane region. We also demonstrate that agouti-related protein, a physiological antagonist of MC4R, acts as an inverse agonist by inhibiting N terminus-mediated activation, leading to the speculation that a number of constitutively active orphan GPCRs could have physiological inverse agonists as sole regulators.
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Affiliation(s)
- Baran A Ersoy
- Department of Medicine, University of California–San Francisco, San Francisco, California, USA
- The Diabetes Center, University of California–San Francisco, San Francisco, California, USA
| | - Leonardo Pardo
- Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Sumei Zhang
- Department of Medicine, University of California–San Francisco, San Francisco, California, USA
- The Diabetes Center, University of California–San Francisco, San Francisco, California, USA
| | - Darren A Thompson
- Department of Chemistry and Biochemistry, University of California–Santa Cruz, Santa Cruz, California, USA
| | - Glenn Millhauser
- Department of Chemistry and Biochemistry, University of California–Santa Cruz, Santa Cruz, California, USA
| | - Cedric Govaerts
- Structure et Fonction des Membranes Biologiques, Université Libre de Bruxelles, Brussels, Belgium
| | - Christian Vaisse
- Department of Medicine, University of California–San Francisco, San Francisco, California, USA
- The Diabetes Center, University of California–San Francisco, San Francisco, California, USA
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30
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Daga PR, Zaveri NT. Homology modeling and molecular dynamics simulations of the active state of the nociceptin receptor reveal new insights into agonist binding and activation. Proteins 2012; 80:1948-61. [PMID: 22489047 DOI: 10.1002/prot.24077] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 03/01/2012] [Accepted: 03/12/2012] [Indexed: 11/11/2022]
Abstract
The opioid receptor-like receptor, also known as the nociceptin receptor (NOP), is a class A G protein-coupled receptor (GPCR) in the opioid receptor family. Although NOP shares a significant homology with the other opioid receptors, it does not bind known opioid ligands and has been shown to have a distinct mechanism of activation compared to the closely related opioid receptors mu, delta, and kappa. Previously reported homology models of the NOP receptor, based on the inactive-state GPCR crystal structures, give limited information on the activation and selectivity features of this fourth member of the opioid receptor family. We report here the first active-state homology model of the NOP receptor based on the opsin GPCR crystal structure. An inactive-state homology model of NOP was also built using a multiple template approach. Molecular dynamics simulation of the active-state NOP model and comparison to the inactive-state model suggest that NOP activation involves movements of transmembrane (TM)3 and TM6 and several activation microswitches, consistent with GPCR activation. Docking of the selective nonpeptidic NOP agonist ligand Ro 64-6198 into the active-state model reveals active-site residues in NOP that play a role in the high selectivity of this ligand for NOP over the other opioid receptors. Docking the shortest active fragment of endogenous agonist nociceptin/orphaninFQ (residues 1-13) shows that the NOP extracellular loop 2 (EL2) loop interacts with the positively charged residues (8-13) of N/OFQ. Both agonists show extensive polar interactions with residues at the extracellular end of the TM domain and EL2 loop, suggesting agonist-induced reorganization of polar networks, during receptor activation.
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Affiliation(s)
- Pankaj R Daga
- Astraea Therapeutics, LLC, 320 Logue Avenue, Mountain View, California 94043, USA
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31
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Molecular modeling of the M3 acetylcholine muscarinic receptor and its binding site. J Biomed Biotechnol 2012; 2012:789741. [PMID: 22500107 PMCID: PMC3303834 DOI: 10.1155/2012/789741] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 11/08/2011] [Indexed: 11/21/2022] Open
Abstract
The present study reports the results of a combined computational and site mutagenesis study designed to provide new insights into the orthosteric binding site of the human M3 muscarinic acetylcholine receptor. For this purpose a three-dimensional structure of the receptor at atomic resolution was built by homology modeling, using the crystallographic structure of bovine rhodopsin as a template. Then, the antagonist N-methylscopolamine was docked in the model and subsequently embedded in a lipid bilayer for its refinement using molecular dynamics simulations. Two different lipid bilayer compositions were studied: one component palmitoyl-oleyl phosphatidylcholine (POPC) and two-component palmitoyl-oleyl phosphatidylcholine/palmitoyl-oleyl phosphatidylserine (POPC-POPS). Analysis of the results suggested that residues F222 and T235 may contribute to the ligand-receptor recognition. Accordingly, alanine mutants at positions 222 and 235 were constructed, expressed, and their binding properties determined. The results confirmed the role of these residues in modulating the binding affinity of the ligand.
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32
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Signalling bias in new drug discovery: detection, quantification and therapeutic impact. Nat Rev Drug Discov 2012; 12:205-16. [PMID: 23411724 DOI: 10.1038/nrd3954] [Citation(s) in RCA: 581] [Impact Index Per Article: 48.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Agonists of seven-transmembrane receptors, also known as G protein-coupled receptors (GPCRs), do not uniformly activate all cellular signalling pathways linked to a given seven-transmembrane receptor (a phenomenon termed ligand or agonist bias); this discovery has changed how high-throughput screens are designed and how lead compounds are optimized for therapeutic activity. The ability to experimentally detect ligand bias has necessitated the development of methods for quantifying agonist bias in a way that can be used to guide structure-activity studies and the selection of drug candidates. Here, we provide a viewpoint on which methods are appropriate for quantifying bias, based on knowledge of how cellular and intracellular signalling proteins control the conformation of seven-transmembrane receptors. We also discuss possible predictions of how biased molecules may perform in vivo, and what potential therapeutic advantages they may provide.
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33
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Lane JR, Klein Herenbrink C, van Westen GJP, Spoorendonk JA, Hoffmann C, IJzerman AP. A novel nonribose agonist, LUF5834, engages residues that are distinct from those of adenosine-like ligands to activate the adenosine A(2a) receptor. Mol Pharmacol 2011; 81:475-87. [PMID: 22188926 DOI: 10.1124/mol.111.075937] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The recent publication of both the antagonist- and agonist-bound structures of the adenosine A(2A) receptor have revealed much about how a ligand may bind to a receptor and cause the conformational changes associated with agonist-mediated activation. In particular, the agonist-bound structure revealed key interactions between the ribose group of adenosine-derived agonists and amino acids in the receptor binding pocket that lead to receptor activation. However, agonists without a ribose group also exist, and we wondered whether such compounds occupy the same agonist binding site. Therefore we used a mutagenesis approach in this study to investigate the mode of binding of 2-amino-4-(4-hydroxyphenyl)- 6-(1H-imidazol-2-ylmethylsulfanyl)pyridine-3,5-dicarbonitrile (LUF5834), a potent partial agonist without a ribose moiety, compared with the adenosine-derived reference agonist 2-[p-(2-carboxyethyl)phenyl-ethylamino]-5'-N-ethylcarboxamidoadenosine (CGS21680). Mutation of the orthosteric residue Phe168 to alanine abrogated the function of both agonists. However, mutation to alanine of residues Thr88 and Ser277 shown by the crystal structures to interact with the ribose group of adenosine-like ligands had no effect on the potency of LUF5834. Furthermore, alanine mutation of Asn253, which makes a hydrogen-bonding interaction with the exocyclic nitrogen of the adenine ring, had minimal effect on LUF5834 affinity but removed agonist activity of this ligand. Mutation of other residues, such as the highly conserved Trp246 or Glu13, had significant deleterious effects on the function of CGS21680 but little effect on LUF5834. In summary, our findings suggest that this class of agonist interacts with distinct residues to activate the receptor compared with classic adenosine derived agonists.
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Affiliation(s)
- J Robert Lane
- Division of Medicinal Chemistry, Leiden/Amsterdam Center for Drug Research, Leiden University, Leiden, the Netherlands.
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34
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Fanelli F, De Benedetti PG. Update 1 of: computational modeling approaches to structure-function analysis of G protein-coupled receptors. Chem Rev 2011; 111:PR438-535. [PMID: 22165845 DOI: 10.1021/cr100437t] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Francesca Fanelli
- Dulbecco Telethon Institute, University of Modena and Reggio Emilia, via Campi 183, 41125 Modena, Italy.
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35
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Kim SK, Riley L, Abrol R, Jacobson KA, Goddard WA. Predicted structures of agonist and antagonist bound complexes of adenosine A3 receptor. Proteins 2011; 79:1878-97. [PMID: 21488099 DOI: 10.1002/prot.23012] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Revised: 01/20/2011] [Accepted: 02/01/2011] [Indexed: 12/11/2022]
Abstract
We used the GEnSeMBLE Monte Carlo method to predict ensemble of the 20 best packings (helix rotations and tilts) based on the neutral total energy (E) from a vast number (10 trillion) of potential packings for each of the four subtypes of the adenosine G protein-coupled receptors (GPCRs), which are involved in many cytoprotective functions. We then used the DarwinDock Monte Carlo methods to predict the binding pose for the human A(3) adenosine receptor (hAA(3)R) for subtype selective agonists and antagonists. We found that all four A(3) agonists stabilize the 15th lowest conformation of apo-hAA(3)R while also binding strongly to the 1st and 3rd. In contrast the four A(3) antagonists stabilize the 2nd or 3rd lowest conformation. These results show that different ligands can stabilize different GPCR conformations, which will likely affect function, complicating the design of functionally unique ligands. Interestingly all agonists lead to a trans χ1 angle for W6.48 that experiments on other GPCRs associate with G-protein activation while all 20 apo-AA(3)R conformations have a W6.48 gauche+ χ1 angle associated experimentally with inactive GPCRs for other systems. Thus docking calculations have identified critical ligand-GPCR structures involved with activation. We found that the predicted binding site for selective agonist Cl-IB-MECA to the predicted structure of hAA(3)R shows favorable interactions to three subtype variable residues, I253(6.58), V169(EL2), and Q167(EL2), while the predicted structure for hAA(2A)R shows weakened to the corresponding amino acids: T256(6.58), E169(EL2), and L167(EL2), explaining the observed subtype selectivity.
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Affiliation(s)
- Soo-Kyung Kim
- Division of Chemistry and Chemical Engineering, Materials and Process Simulation Center MC139-74, California Institute of Technology, Pasadena, California 91125, USA
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36
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Rasmussen SGF, Choi HJ, Fung JJ, Pardon E, Casarosa P, Chae PS, Devree BT, Rosenbaum DM, Thian FS, Kobilka TS, Schnapp A, Konetzki I, Sunahara RK, Gellman SH, Pautsch A, Steyaert J, Weis WI, Kobilka BK. Structure of a nanobody-stabilized active state of the β(2) adrenoceptor. Nature 2011; 469:175-80. [PMID: 21228869 PMCID: PMC3058308 DOI: 10.1038/nature09648] [Citation(s) in RCA: 1307] [Impact Index Per Article: 100.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Accepted: 11/01/2010] [Indexed: 11/16/2022]
Abstract
G protein coupled receptors (GPCRs) exhibit a spectrum of functional behaviors in response to natural and synthetic ligands. Recent crystal structures provide insights into inactive states of several GPCRs. Efforts to obtain an agonist-bound active-state GPCR structure have proven difficult due to the inherent instability of this state in the absence of a G protein. We generated a camelid antibody fragment (nanobody) to the human β2 adrenergic receptor (β2AR) that exhibits G protein-like behavior, and obtained an agonist-bound, active-state crystal structure of the receptor-nanobody complex. Comparison with the inactive β2AR structure reveals subtle changes in the binding pocket; however, these small changes are associated with an 11Å outward movement of the cytoplasmic end of transmembrane segment 6, and rearrangements of transmembrane segments 5 and 7 that are remarkably similar to those observed in opsin, an active form of rhodopsin. This structure provides insights into the process of agonist binding and activation.
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Affiliation(s)
- Søren G F Rasmussen
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 279 Campus Drive, Stanford, California 94305, USA
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37
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Arakawa M, Chakraborty R, Upadhyaya J, Eilers M, Reeves PJ, Smith SO, Chelikani P. Structural and functional roles of small group-conserved amino acids present on helix-H7 in the β(2)-adrenergic receptor. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:1170-8. [PMID: 21262196 DOI: 10.1016/j.bbamem.2011.01.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Revised: 12/23/2010] [Accepted: 01/19/2011] [Indexed: 11/19/2022]
Abstract
Sequence analysis of the class A G protein-coupled receptors (GPCRs) reveals that most of the highly conserved sites are located in the transmembrane helices. A second level of conservation exists involving those residues that are conserved as a group characterized by small and/or weakly polar side chains (Ala, Gly, Ser, Cys, Thr). These positions can have group conservation levels of up to 99% across the class A GPCRs and have been implicated in mediating helix-helix interactions in membrane proteins. We have previously shown that mutation of group-conserved residues present on transmembrane helices H2-H4 in the β(2)-adrenergic receptor (β(2)-AR) can influence both receptor expression and function. We now target the group-conserved sites, Gly315(7.42) and Ser319(7.46), on H7 for structure-function analysis. Replacing Ser319(7.46) with smaller amino acids (Ala or Gly) did not influence the ability of the mutant receptors to bind to the antagonist dihydroalprenolol (DHA) but resulted in ~15-20% agonist-independent activity. Replacement of Ser319(7.46) with the larger amino acid leucine lowered the expression of the S319L mutant and its ability to bind DHA. Both the G315A and G315S mutants also exhibited agonist-independent signaling, while the G315L mutant did not show specific binding to DHA. These data indicate that Gly315(7.42) and Ser319(7.46) are stabilizing β(2)-AR in an inactive conformation. We discuss our results in the context of van der Waals interactions of Gly315(7.42) with Trp286(6.48) and hydrogen bonding interactions of Ser319(7.46) with amino acids on H1-H2-H7 and with structural water.
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Affiliation(s)
- Makoto Arakawa
- Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W4, Canada
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38
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Pellissier LP, Barthet G, Gaven F, Cassier E, Trinquet E, Pin JP, Marin P, Dumuis A, Bockaert J, Banères JL, Claeysen S. G protein activation by serotonin type 4 receptor dimers: evidence that turning on two protomers is more efficient. J Biol Chem 2011; 286:9985-97. [PMID: 21247891 DOI: 10.1074/jbc.m110.201939] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The discovery that class C G protein-coupled receptors (GPCRs) function as obligatory dimeric entities has generated major interest in GPCR oligomerization. Oligomerization now appears to be a common feature among all GPCR classes. However, the functional significance of this process remains unclear because, in vitro, some monomeric GPCRs, such as rhodopsin and β(2)-adrenergic receptors, activate G proteins. By using wild type and mutant serotonin type 4 receptors (5-HT(4)Rs) (including a 5-HT(4)-RASSL) expressed in COS-7 cells as models of class A GPCRs, we show that activation of one protomer in a dimer was sufficient to stimulate G proteins. However, coupling efficiency was 2 times higher when both protomers were activated. Expression of combinations of 5-HT(4), in which both protomers were able to bind to agonists but only one could couple to G proteins, suggested that upon agonist occupancy, protomers did not independently couple to G proteins but rather that only one G protein was activated. Coupling of a single heterotrimeric G(s) protein to a receptor dimer was further confirmed in vitro, using the purified recombinant WT RASSL 5-HT(4)R obligatory heterodimer. These results, together with previous findings, demonstrate that, differently from class C GPCR dimers, class A GPCR dimers have pleiotropic activation mechanisms.
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Affiliation(s)
- Lucie P Pellissier
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS UMR5203, F-34094 Montpellier, France
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39
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Abstract
Receptors on the surface of cells function as conduits for information flowing between the external environment and the cell interior. Since signal transduction is based on the physical interaction of receptors with both extracellular ligands and intracellular effectors, ligand binding must produce conformational changes in the receptor that can be transmitted to the intracellular domains accessible to G proteins and other effectors. Classical models of G protein-coupled receptor (GPCR) signaling envision receptor conformations as highly constrained, wherein receptors exist in equilibrium between single "off" and "on" states distinguished by their ability to activate effectors, and ligands act by perturbing this equilibrium. In such models, ligands can be classified based upon two simple parameters; affinity and efficacy, and ligand activity is independent of the assay used to detect the response. However, it is clear that GPCRs assume multiple conformations, any number of which may be capable of interacting with a discrete subset of possible effectors. Both orthosteric ligands, molecules that occupy the natural ligand-binding pocket, and allosteric modulators, small molecules or proteins that contact receptors distant from the site of ligand binding, have the ability to alter the conformational equilibrium of a receptor in ways that affect its signaling output both qualitatively and quantitatively. In this context, efficacy becomes pluridimensional and ligand classification becomes assay dependent. A more complete description of ligand-receptor interaction requires the use of multiplexed assays of receptor activation and screening assays may need to be tailored to detect specific efficacy profiles.
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40
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González A, Murcia M, Benhamú B, Campillo M, López-Rodríguez ML, Pardo L. The importance of solvation in the design of ligands targeting membrane proteins. MEDCHEMCOMM 2011. [DOI: 10.1039/c0md00258e] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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41
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Kenakin T, Miller LJ. Seven transmembrane receptors as shapeshifting proteins: the impact of allosteric modulation and functional selectivity on new drug discovery. Pharmacol Rev 2010; 62:265-304. [PMID: 20392808 DOI: 10.1124/pr.108.000992] [Citation(s) in RCA: 458] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
It is useful to consider seven transmembrane receptors (7TMRs) as disordered proteins able to allosterically respond to a number of binding partners. Considering 7TMRs as allosteric systems, affinity and efficacy can be thought of in terms of energy flow between a modulator, conduit (the receptor protein), and a number of guests. These guests can be other molecules, receptors, membrane-bound proteins, or signaling proteins in the cytosol. These vectorial flows of energy can yield standard canonical guest allostery (allosteric modification of drug effect), effects along the plane of the cell membrane (receptor oligomerization), or effects directed into the cytosol (differential signaling as functional selectivity). This review discusses these apparently diverse pharmacological effects in terms of molecular dynamics and protein ensemble theory, which tends to unify 7TMR behavior toward cells. Special consideration will be given to functional selectivity (biased agonism and biased antagonism) in terms of mechanism of action and potential therapeutic application. The explosion of technology that has enabled observation of diverse 7TMR behavior has also shown how drugs can have multiple (pluridimensional) efficacies and how this can cause paradoxical drug classification and nomenclatures.
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Affiliation(s)
- Terry Kenakin
- GlaxoSmithKline, 5 Moore Drive, Mailtstop V-287, Research Triangle Park, NC 27709, USA.
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de la Fuente T, Martín-Fontecha M, Sallander J, Benhamú B, Campillo M, Medina RA, Pellissier LP, Claeysen S, Dumuis A, Pardo L, López-Rodríguez ML. Benzimidazole derivatives as new serotonin 5-HT6 receptor antagonists. Molecular mechanisms of receptor inactivation. J Med Chem 2010; 53:1357-69. [PMID: 20078106 DOI: 10.1021/jm901672k] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
On the basis of our previously described pharmacophore model for serotonin 5-HT(6) receptor (5-HT(6)R) antagonists, we have designed, synthesized, and pharmacologically characterized a series of benzimidazole derivatives 1-20 that represent a new family of potent antagonists at the human 5-HT(6)R. Site-directed mutagenesis and a beta(2)-adrenoceptor-based homology model of the 5-HT(6)R were used to predict the mode of binding of antagonist SB-258585 and the new synthesized ligands. Substitution of W6.48, F6.52, or N6.55 by Ala fully impedes compound 4 to block 5-HT-induced activation. Thus, we propose that D3.32 in TM 3 anchors the protonated piperazine ring, the benzimidazole ring expands parallel to EL 2 to hydrogen bond N6.55 in TM 6, and the aromatic ring is placed between TMs 3 and 5 in CH(2)-containing compounds and between TMs 3 and 6 in CO-containing compounds. This combined experimental and computational study has permitted to propose the molecular mechanisms by which the new benzimidazole derivatives act as 5-HT(6)R antagonists.
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Affiliation(s)
- Tania de la Fuente
- Departamento de Química Orgánica I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, E-28040 Madrid, Spain
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Mnie-Filali O, Amraei MG, Benmbarek S, Archer-Lahlou E, Peñas-Cazorla R, Vilaró MT, Boye SM, Piñeyro G. Serotonin 4 receptor (5-HT4R) internalization is isoform-specific: effects of 5-HT and RS67333 on isoforms A and B. Cell Signal 2010; 22:501-9. [PMID: 19922792 DOI: 10.1016/j.cellsig.2009.11.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2009] [Revised: 10/25/2009] [Accepted: 11/09/2009] [Indexed: 11/25/2022]
Abstract
Serotonin 4 receptors (5-HT4Rs) are particularly abundant within the limbic system, where they constitute potential targets for the development of novel, rapid acting antidepressants. However, the population of limbic 5-HT4Rs is not homogenous, comprising various isoforms of which 5-HT4(a) and 5-HT4(b) are among the most abundant variants. Sequence divergence at their C-termini is predictive of specificity in isoform signalling and regulation, but the differences, if any, remain ill-defined. The present study compared isoforms 5-HT4(a) and 5-HT4(b) in their ability to undergo endocytic regulation following exposure to 5-HT and to the putatively fast acting antidepressant RS67333. Both ligands differed in their ability to induce internalization of either isoform, 5-HT being more effective than RS67333 in HEK293 cells and in neurons. In contrast, trafficking induced by 5-HT was isoform-specific. In particular, while PKC, GRK2 and betaarrestin were necessary for 5-HT4(a)R internalization, sequestration of 5-HT4(b)Rs required PKC but not GRK2 and relied significantly less on betaarrestin. After endocytosis, isoform (b) appeared scattered throughout the intracellular compartment and efficiently recycled to the membrane upon agonist removal. Isoform (a) accumulated in the perinuclear compartment and displayed little recycling. Isoform-specific subcellular distribution was present in HEK293 cells and in neurons. In neurons, where internalization by RS67333 was more pronounced than in HEK293 cells, receptors internalized by this ligand followed the same distribution pattern as observed with 5-HT. These results point to isoform-related differences in the way that 5-HTRs respond to different ligands. Such diversity should be taken into account when developing therapeutic agents that target 5-HT4Rs.
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Affiliation(s)
- O Mnie-Filali
- Department of Pharmacology, Faculty of Medicine, University of Montreal, and Centre de Recherche de l'Hôpital Ste Justine, Montreal, Quebec, Canada
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McRobb FM, Capuano B, Crosby IT, Chalmers DK, Yuriev E. Homology Modeling and Docking Evaluation of Aminergic G Protein-Coupled Receptors. J Chem Inf Model 2010; 50:626-37. [DOI: 10.1021/ci900444q] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Fiona M. McRobb
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, VIC 3052 Australia
| | - Ben Capuano
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, VIC 3052 Australia
| | - Ian T. Crosby
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, VIC 3052 Australia
| | - David K. Chalmers
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, VIC 3052 Australia
| | - Elizabeth Yuriev
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, VIC 3052 Australia
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Mueller S, Jaeschke H, Paschke R. Current standards, variations, and pitfalls for the determination of constitutive TSHR activity in vitro. Methods Enzymol 2010; 485:421-36. [PMID: 21050930 DOI: 10.1016/b978-0-12-381296-4.00023-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Constitutively activating mutations of the TSHR are the major cause for nonautoimmune hyperthyroidism, which is based on ligand independent, permanent receptor activation. Several reports have highlighted the difficulties to determine whether a TSHR mutation is constitutively active or not especially for borderline cases with only a slight increase of the basal cAMP activity. Current methods to precisely classify such mutants as constitutively active or not, are limited. In some cases, in vitro characterization of TSHR mutants has led to false positive conclusions regarding constitutive TSHR activity and subsequently the molecular origin of hyperthyroidism. For characterization of constitutive TSHR activity, a particular point to consider is that basal receptor activity tightly correlates with the receptor number expressed on the cell surface. Therefore, a comparison of the receptors basal activity in relation to the wild type is only possible with determination of the receptor cell surface expression. Thus, the experimental approaches to determine constitutive TSHR activity should consider the receptor's cell surface expression. We here provide a description of three methods for the determination of constitutive TSHR activity: (A) the evaluation of constitutive TSHR activity under conditions of equal receptor expression; (B) computation of the specific constitutive activity; and (C) the linear regression analysis (LRA). To date, LRA is the best experimental approach to characterize the mutant's basal activity as a function of TSHR cell surface expression. This approach utilizes a parallel measurement of basal cAMP values and receptor cell surface expression and therefore provides a more reliable decision with respect to the presence or absence of constitutive activity.
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Affiliation(s)
- Sandra Mueller
- Department for Internal Medicine, Neurology and Dermatology, Clinic for Endocrinology and Nephrology, University of Leipzig, Leipzig, Germany
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Holst B, Nygaard R, Valentin-Hansen L, Bach A, Engelstoft MS, Petersen PS, Frimurer TM, Schwartz TW. A conserved aromatic lock for the tryptophan rotameric switch in TM-VI of seven-transmembrane receptors. J Biol Chem 2009; 285:3973-3985. [PMID: 19920139 DOI: 10.1074/jbc.m109.064725] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The conserved tryptophan in position 13 of TM-VI (Trp-VI:13 or Trp-6.48) of the CWXP motif located at the bottom of the main ligand-binding pocket in TM-VI is believed to function as a rotameric microswitch in the activation process of seven-transmembrane (7TM) receptors. Molecular dynamics simulations in rhodopsin demonstrated that rotation around the chi1 torsion angle of Trp-VI:13 brings its side chain close to the equally highly conserved Phe-V:13 (Phe-5.47) in TM-V. In the ghrelin receptor, engineering of high affinity metal-ion sites between these positions confirmed their close spatial proximity. Mutational analysis was performed in the ghrelin receptor with multiple substitutions and with Ala substitutions in GPR119, GPR39, and the beta(2)-adrenergic receptor as well as the NK1 receptor. In all of these cases, it was found that mutation of the Trp-VI:13 rotameric switch itself eliminated the constitutive signaling and strongly impaired agonist-induced signaling without affecting agonist affinity and potency. Ala substitution of Phe-V:13, the presumed interaction partner for Trp-VI:13, also in all cases impaired both the constitutive and the agonist-induced receptor signaling, but not to the same degree as observed in the constructs where Trp-VI:13 itself was mutated, but again without affecting agonist potency. In a proposed active receptor conformation generated by molecular simulations, where the extracellular segment of TM-VI is tilted inwards in the main ligand-binding pocket, Trp-VI:13 could rotate into a position where it obtained an ideal aromatic-aromatic interaction with Phe-V:13. It is concluded that Phe-V:13 can serve as an aromatic lock for the proposed active conformation of the Trp-VI:13 rotameric switch, being involved in the global movement of TM-V and TM-VI in 7TM receptor activation.
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Affiliation(s)
- Birgitte Holst
- From the Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, Blegdamsvej 3, DK2200 Copenhagen, Denmark and.
| | - Rie Nygaard
- From the Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, Blegdamsvej 3, DK2200 Copenhagen, Denmark and; 7TM Pharma A/S, Fremtidsvej 3, DK5700 Hørsholm, Denmark
| | - Louise Valentin-Hansen
- From the Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, Blegdamsvej 3, DK2200 Copenhagen, Denmark and
| | - Anders Bach
- From the Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, Blegdamsvej 3, DK2200 Copenhagen, Denmark and
| | - Maja S Engelstoft
- From the Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, Blegdamsvej 3, DK2200 Copenhagen, Denmark and
| | - Pia S Petersen
- From the Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, Blegdamsvej 3, DK2200 Copenhagen, Denmark and
| | | | - Thue W Schwartz
- From the Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, Blegdamsvej 3, DK2200 Copenhagen, Denmark and; 7TM Pharma A/S, Fremtidsvej 3, DK5700 Hørsholm, Denmark.
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