1
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Heydenreich FM, Marti-Solano M, Sandhu M, Kobilka BK, Bouvier M, Babu MM. Molecular determinants of ligand efficacy and potency in GPCR signaling. Science 2023; 382:eadh1859. [PMID: 38127743 PMCID: PMC7615523 DOI: 10.1126/science.adh1859] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 11/07/2023] [Indexed: 12/23/2023]
Abstract
Heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) bind to extracellular ligands and drugs and modulate intracellular responses through conformational changes. Despite their importance as drug targets, the molecular origins of pharmacological properties such as efficacy (maximum signaling response) and potency (the ligand concentration at half-maximal response) remain poorly understood for any ligand-receptor-signaling system. We used the prototypical adrenaline-β2 adrenergic receptor-G protein system to reveal how specific receptor residues decode and translate the information encoded in a ligand to mediate a signaling response. We present a data science framework to integrate pharmacological and structural data to uncover structural changes and allosteric networks relevant for ligand pharmacology. These methods can be tailored to study any ligand-receptor-signaling system, and the principles open possibilities for designing orthosteric and allosteric compounds with defined signaling properties.
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Affiliation(s)
- Franziska M. Heydenreich
- Department of Molecular and Cellular Physiology, Stanford University
School of Medicine, Stanford, CA, USA
- MRC Laboratory of Molecular Biology, Cambridge, UK
- Department of Biochemistry and Molecular Medicine, Institute for
Research in Immunology and Cancer, Université de Montréal, Montreal,
QC, Canada
| | - Maria Marti-Solano
- MRC Laboratory of Molecular Biology, Cambridge, UK
- Department of Pharmacology, University of Cambridge, Cambridge,
UK
| | - Manbir Sandhu
- Department of Pharmacology, University of Cambridge, Cambridge,
UK
| | - Brian K. Kobilka
- Department of Molecular and Cellular Physiology, Stanford University
School of Medicine, Stanford, CA, USA
| | - Michel Bouvier
- Department of Biochemistry and Molecular Medicine, Institute for
Research in Immunology and Cancer, Université de Montréal, Montreal,
QC, Canada
| | - M. Madan Babu
- MRC Laboratory of Molecular Biology, Cambridge, UK
- Department of Structural Biology and Center of Excellence for
Data-Driven Discovery, St. Jude Children’s Research Hospital, Memphis, TN,
USA
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2
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Chiesa L, Sick E, Kellenberger E. Predicting the duration of action of β2-adrenergic receptor agonists: Ligand and structure-based approaches. Mol Inform 2023; 42:e202300141. [PMID: 37872120 DOI: 10.1002/minf.202300141] [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: 06/11/2023] [Revised: 10/17/2023] [Accepted: 10/23/2023] [Indexed: 10/25/2023]
Abstract
Agonists of the β2 adrenergic receptor (ADRB2) are an important class of medications used for the treatment of respiratory diseases. They can be classified as short acting (SABA) or long acting (LABA), with each class playing a different role in patient management. In this work we explored both ligand-based and structure-based high-throughput approaches to classify β2-agonists based on their duration of action. A completely in-silico prediction pipeline using an AlphaFold generated structure was used for structure-based modelling. Our analysis identified the ligands' 3D structure and lipophilicity as the most relevant features for the prediction of the duration of action. Interaction-based methods were also able to select ligands with the desired duration of action, incorporating the bias directly in the structure-based drug discovery pipeline without the need for further processing.
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Affiliation(s)
- Luca Chiesa
- Laboratoire d'Innovation Thérapeutique, Faculté de Pharmacie, UMR7200 CNRS Université de Strasbourg, 67400, Illkirch, France
| | - Emilie Sick
- Laboratoire de Conception et Application de Molécules Bioactives, Faculté de Pharmacie, UMR7199 CNRS Université de Strasbourg, 67400, Illkirch, France
| | - Esther Kellenberger
- Laboratoire d'Innovation Thérapeutique, Faculté de Pharmacie, UMR7200 CNRS Université de Strasbourg, 67400, Illkirch, France
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3
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Su M, Wang J, Xiang G, Do HN, Levitz J, Miao Y, Huang XY. Structural basis of agonist specificity of α 1A-adrenergic receptor. Nat Commun 2023; 14:4819. [PMID: 37563160 PMCID: PMC10415349 DOI: 10.1038/s41467-023-40524-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 07/27/2023] [Indexed: 08/12/2023] Open
Abstract
α1-adrenergic receptors (α1-ARs) play critical roles in the cardiovascular and nervous systems where they regulate blood pressure, cognition, and metabolism. However, the lack of specific agonists for all α1 subtypes has limited our understanding of the physiological roles of different α1-AR subtypes, and led to the stagnancy in agonist-based drug development for these receptors. Here we report cryo-EM structures of α1A-AR in complex with heterotrimeric G-proteins and either the endogenous common agonist epinephrine or the α1A-AR-specific synthetic agonist A61603. These structures provide molecular insights into the mechanisms underlying the discrimination between α1A-AR and α1B-AR by A61603. Guided by the structures and corresponding molecular dynamics simulations, we engineer α1A-AR mutants that are not responsive to A61603, and α1B-AR mutants that can be potently activated by A61603. Together, these findings advance our understanding of the agonist specificity for α1-ARs at the molecular level, opening the possibility of rational design of subtype-specific agonists.
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Affiliation(s)
- Minfei Su
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, NY, 10065, USA
| | - Jinan Wang
- Center for Computational Biology and Department of Molecular Biosciences, University of Kansas, Lawrence, KS, 66047, USA
| | - Guoqing Xiang
- Department of Biochemistry, Weill Cornell Medical College of Cornell University, New York, NY, 10065, USA
- Department of Psychiatry, Weill Cornell Medical College of Cornell University, New York, NY, 10065, USA
| | - Hung Nguyen Do
- Center for Computational Biology and Department of Molecular Biosciences, University of Kansas, Lawrence, KS, 66047, USA
| | - Joshua Levitz
- Department of Biochemistry, Weill Cornell Medical College of Cornell University, New York, NY, 10065, USA
- Department of Psychiatry, Weill Cornell Medical College of Cornell University, New York, NY, 10065, USA
| | - Yinglong Miao
- Center for Computational Biology and Department of Molecular Biosciences, University of Kansas, Lawrence, KS, 66047, USA.
| | - Xin-Yun Huang
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, NY, 10065, USA.
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4
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Liu T, Ji RL, Tao YX. Naturally occurring mutations in G protein-coupled receptors associated with obesity and type 2 diabetes mellitus. Pharmacol Ther 2021; 234:108044. [PMID: 34822948 DOI: 10.1016/j.pharmthera.2021.108044] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 11/15/2021] [Accepted: 11/15/2021] [Indexed: 12/12/2022]
Abstract
G protein-coupled receptors (GPCRs) are the largest family of membrane receptors involved in the regulation of almost all known physiological processes. Dysfunctions of GPCR-mediated signaling have been shown to cause various diseases. The prevalence of obesity and type 2 diabetes mellitus (T2DM), two strongly associated disorders, is increasing worldwide, with tremendous economical and health burden. New safer and more efficacious drugs are required for successful weight reduction and T2DM treatment. Multiple GPCRs are involved in the regulation of energy and glucose homeostasis. Mutations in these GPCRs contribute to the development and progression of obesity and T2DM. Therefore, these receptors can be therapeutic targets for obesity and T2DM. Indeed some of these receptors, such as melanocortin-4 receptor and glucagon-like peptide 1 receptor, have provided important new drugs for treating obesity and T2DM. This review will focus on the naturally occurring mutations of several GPCRs associated with obesity and T2DM, especially incorporating recent large genomic data and insights from structure-function studies, providing leads for future investigations.
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Affiliation(s)
- Ting Liu
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, AL 36849, United States
| | - Ren-Lei Ji
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, AL 36849, United States
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, AL 36849, United States.
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5
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Sogunmez N, Akten ED. Distinctive communication networks in inactive states of β 2 -adrenergic receptor: Mutual information and entropy transfer analysis. Proteins 2020; 88:1458-1471. [PMID: 32530095 DOI: 10.1002/prot.25965] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 04/26/2020] [Accepted: 06/06/2020] [Indexed: 12/21/2022]
Abstract
Mutual information and entropy transfer analysis employed on two inactive states of human beta-2 adrenergic receptor (β2 -AR) unraveled distinct communication pathways. Previously, a so-called "highly" inactive state of the receptor was observed during 1.5 microsecond long molecular dynamics simulation where the largest intracellular loop (ICL3) was swiftly packed onto the G-protein binding cavity, becoming entirely inaccessible. Mutual information quantifying the degree of correspondence between backbone-Cα fluctuations was mostly shared between intra- and extra-cellular loop regions in the original inactive state, but shifted to entirely different regions in this latest inactive state. Interestingly, the largest amount of mutual information was always shared among the mobile regions. Irrespective of the conformational state, polar residues always contributed more to mutual information than hydrophobic residues, and also the number of polar-polar residue pairs shared the highest degree of mutual information compared to those incorporating hydrophobic residues. Entropy transfer, quantifying the correspondence between backbone-Cα fluctuations at different timesteps, revealed a distinctive pathway directed from the extracellular site toward intracellular portions in this recently exposed inactive state for which the direction of information flow was the reverse of that observed in the original inactive state where the mobile ICL3 and its intracellular surroundings drove the future fluctuations of extracellular regions.
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Affiliation(s)
- Nuray Sogunmez
- Graduate Program of Bioinformatics and Genetics, Graduate School of Science and Engineering, Kadir Has University, Istanbul, Turkey
| | - Ebru Demet Akten
- Department of Bioinformatics and Genetics, Faculty of Engineering and Natural Sciences, Kadir Has University, Istanbul, Turkey
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6
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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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7
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Chudyk EI, Sarrat L, Aldeghi M, Fedorov DG, Bodkin MJ, James T, Southey M, Robinson R, Morao I, Heifetz A. Exploring GPCR-Ligand Interactions with the Fragment Molecular Orbital (FMO) Method. Methods Mol Biol 2018; 1705:179-195. [PMID: 29188563 DOI: 10.1007/978-1-4939-7465-8_8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The understanding of binding interactions between any protein and a small molecule plays a key role in the rationalization of affinity and selectivity. It is essential for an efficient structure-based drug design (SBDD) process. FMO enables ab initio approaches to be applied to systems that conventional quantum-mechanical (QM) methods would find challenging. The key advantage of the Fragment Molecular Orbital Method (FMO) is that it can reveal atomistic details about the individual contributions and chemical nature of each residue and water molecule toward ligand binding which would otherwise be difficult to detect without using QM methods. In this chapter, we demonstrate the typical use of FMO to analyze 19 crystal structures of β1 and β2 adrenergic receptors with their corresponding agonists and antagonists.
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Affiliation(s)
- Ewa I Chudyk
- Evotec (UK) Ltd., 114 Innovation Drive, Milton Park, Abingdon, Oxfordshire, OX14 4RZ, UK
| | - Laurie Sarrat
- Evotec (UK) Ltd., 114 Innovation Drive, Milton Park, Abingdon, Oxfordshire, OX14 4RZ, UK
| | - Matteo Aldeghi
- Evotec (UK) Ltd., 114 Innovation Drive, Milton Park, Abingdon, Oxfordshire, OX14 4RZ, UK
| | - Dmitri G Fedorov
- CD-FMat, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki, 305-8568, Japan
| | - Mike J Bodkin
- Evotec (UK) Ltd., 114 Innovation Drive, Milton Park, Abingdon, Oxfordshire, OX14 4RZ, UK
| | - Tim James
- Evotec (UK) Ltd., 114 Innovation Drive, Milton Park, Abingdon, Oxfordshire, OX14 4RZ, UK
| | - Michelle Southey
- Evotec (UK) Ltd., 114 Innovation Drive, Milton Park, Abingdon, Oxfordshire, OX14 4RZ, UK
| | - Roger Robinson
- Evotec (UK) Ltd., 114 Innovation Drive, Milton Park, Abingdon, Oxfordshire, OX14 4RZ, UK
| | - Inaki Morao
- Evotec (UK) Ltd., 114 Innovation Drive, Milton Park, Abingdon, Oxfordshire, OX14 4RZ, UK
| | - Alexander Heifetz
- Evotec (UK) Ltd., 114 Innovation Drive, Milton Park, Abingdon, Oxfordshire, OX14 4RZ, UK.
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8
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Emtage AL, Mistry SN, Fischer PM, Kellam B, Laughton CA. GPCRs through the keyhole: the role of protein flexibility in ligand binding to β-adrenoceptors. J Biomol Struct Dyn 2016; 35:2604-2619. [DOI: 10.1080/07391102.2016.1226197] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Abigail L. Emtage
- School of Pharmacy and Centre for Biomolecular Sciences, The University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Shailesh N. Mistry
- School of Pharmacy and Centre for Biomolecular Sciences, The University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Peter M. Fischer
- School of Pharmacy and Centre for Biomolecular Sciences, The University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Barrie Kellam
- School of Pharmacy and Centre for Biomolecular Sciences, The University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Charles A. Laughton
- School of Pharmacy and Centre for Biomolecular Sciences, The University of Nottingham, University Park, Nottingham NG7 2RD, UK
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9
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Astrocytic β2-adrenergic receptors mediate hippocampal long-term memory consolidation. Proc Natl Acad Sci U S A 2016; 113:8526-31. [PMID: 27402767 DOI: 10.1073/pnas.1605063113] [Citation(s) in RCA: 131] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Emotionally relevant experiences form strong and long-lasting memories by critically engaging the stress hormone/neurotransmitter noradrenaline, which mediates and modulates the consolidation of these memories. Noradrenaline acts through adrenergic receptors (ARs), of which β2-adrenergic receptors (βARs) are of particular importance. The differential anatomical and cellular distribution of βAR subtypes in the brain suggests that they play distinct roles in memory processing, although much about their specific contributions and mechanisms of action remains to be understood. Here we show that astrocytic rather than neuronal β2ARs in the hippocampus play a key role in the consolidation of a fear-based contextual memory. These hippocampal β2ARs, but not β1ARs, are coupled to the training-dependent release of lactate from astrocytes, which is necessary for long-term memory formation and for underlying molecular changes. This key metabolic role of astrocytic β2ARs may represent a novel target mechanism for stress-related psychopathologies and neurodegeneration.
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10
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Pachov DV, Fonseca R, Arnol D, Bernauer J, van den Bedem H. Coupled Motions in β2AR:Gαs Conformational Ensembles. J Chem Theory Comput 2016; 12:946-56. [DOI: 10.1021/acs.jctc.5b00995] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Dimitar V. Pachov
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
- Division
of Biosciences, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
| | - Rasmus Fonseca
- Division
of Biosciences, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
- AMIB
INRIA - Bioinformatics group, LIX, École Polytechnique, 91128 Palaiseau, France
| | - Damien Arnol
- INRIA Saclay-Île de France, 1 rue Honoré d'Estienne
d'Orves, Bâtiment Alan Turing, Campus de l'École
Polytechnique, 91120 Palaiseau, France
- Laboratoire
d'Informatique de l'École Polytechnique (LIX), CNRS
UMR 7161, École Polytechnique, 91128 Palaiseau, France
| | - Julie Bernauer
- INRIA Saclay-Île de France, 1 rue Honoré d'Estienne
d'Orves, Bâtiment Alan Turing, Campus de l'École
Polytechnique, 91120 Palaiseau, France
- Laboratoire
d'Informatique de l'École Polytechnique (LIX), CNRS
UMR 7161, École Polytechnique, 91128 Palaiseau, France
| | - Henry van den Bedem
- Division
of Biosciences, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
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11
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Randáková A, Dolejší E, Rudajev V, Zimčík P, Doležal V, El-Fakahany EE, Jakubík J. Classical and atypical agonists activate M1 muscarinic acetylcholine receptors through common mechanisms. Pharmacol Res 2015; 97:27-39. [DOI: 10.1016/j.phrs.2015.04.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 04/03/2015] [Accepted: 04/03/2015] [Indexed: 01/24/2023]
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12
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Buried ionizable networks are an ancient hallmark of G protein-coupled receptor activation. Proc Natl Acad Sci U S A 2015; 112:5702-7. [PMID: 25902551 DOI: 10.1073/pnas.1417888112] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Seven-transmembrane receptors (7TMRs) have evolved in prokaryotes and eukaryotes over hundreds of millions of years. Comparative structural analysis suggests that these receptors may share a remote evolutionary origin, despite their lack of sequence similarity. Here we used structure-based computations to compare 221 7TMRs from all domains of life. Unexpectedly, we discovered that these receptors contain spatially conserved networks of buried ionizable groups. In microbial 7TMRs these networks are used to pump ions across the cell membrane in response to light. In animal 7TMRs, which include light- and ligand-activated G protein-coupled receptors (GPCRs), homologous networks were found to be characteristic of activated receptor conformations. These networks are likely relevant to receptor function because they connect the ligand-binding pocket of the receptor to the nucleotide-binding pocket of the G protein. We propose that agonist and G protein binding facilitate the formation of these electrostatic networks and promote important structural rearrangements such as the displacement of transmembrane helix-6. We anticipate that robust classification of activated GPCR structures will aid the identification of ligands that target activated GPCR structural states.
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13
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Jiang L, Chen SH, Chu CH, Wang SJ, Oyarzabal E, Wilson B, Sanders V, Xie K, Wang Q, Hong JS. A novel role of microglial NADPH oxidase in mediating extra-synaptic function of norepinephrine in regulating brain immune homeostasis. Glia 2015; 63:1057-72. [PMID: 25740080 DOI: 10.1002/glia.22801] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 01/15/2015] [Indexed: 12/30/2022]
Abstract
Although the peripheral anti-inflammatory effect of norepinephrine (NE) is well documented, the mechanism by which this neurotransmitter functions as an anti-inflammatory/neuroprotective agent in the central nervous system (CNS) is unclear. This article aimed to determine the anti-inflammatory/neuroprotective effects and underlying mechanisms of NE in inflammation-based dopaminergic neurotoxicity models. In mice, NE-depleting toxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) was injected at 6 months of lipopolysaccharide (LPS)-induced neuroinflammation. It was found that NE depletion enhanced LPS-induced dopaminergic neuron loss in the substantia nigra. This piece of in vivo data prompted us to conduct a series of studies in an effort to elucidate the mechanism as to how NE affects dopamine neuron survival by using primary midbrain neuron/glia cultures. Results showed that submicromolar concentrations of NE dose-dependently protected dopaminergic neurons from LPS-induced neurotoxicity by inhibiting microglia activation and subsequent release of pro-inflammatory factors. However, NE-elicited neuroprotection was not totally abolished in cultures from β2-adrenergic receptor (β2-AR)-deficient mice, suggesting that novel pathways other than β2-AR are involved. To this end, It was found that submicromolar NE dose-dependently inhibited NADPH oxidase (NOX2)-generated superoxide, which contributes to the anti-inflammatory and neuroprotective effects of NE. This novel mechanism was indeed adrenergic receptors independent since both (+) and (-) optic isomers of NE displayed the same potency. We further demonstrated that NE inhibited LPS-induced NOX2 activation by blocking the translocation of its cytosolic subunit to plasma membranes. In summary, we revealed a potential physiological role of NE in maintaining brain immune homeostasis and protecting neurons via a novel mechanism.
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Affiliation(s)
- Lulu Jiang
- Institute of Toxicology, School of Public Health, Shandong University, Jinan, Shandong, 250012, China; Neuropharmacology Section, Laboratory of Neurobiology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, 27709
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14
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Lakkaraju SK, Yu W, Raman EP, Hershfeld AV, Fang L, Deshpande DA, MacKerell AD. Mapping functional group free energy patterns at protein occluded sites: nuclear receptors and G-protein coupled receptors. J Chem Inf Model 2015; 55:700-8. [PMID: 25692383 PMCID: PMC4372819 DOI: 10.1021/ci500729k] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
![]()
Occluded ligand-binding pockets (LBP)
such as those found in nuclear
receptors (NR) and G-protein coupled receptors (GPCR) represent a
significant opportunity and challenge for computer-aided drug design.
To determine free energies maps of functional groups of these LBPs,
a Grand-Canonical Monte Carlo/Molecular Dynamics (GCMC/MD) strategy
is combined with the Site Identification by Ligand Competitive Saturation
(SILCS) methodology. SILCS-GCMC/MD is shown to map functional group
affinity patterns that recapitulate locations of functional groups
across diverse classes of ligands in the LBPs of the androgen (AR)
and peroxisome proliferator-activated-γ (PPARγ) NRs and
the metabotropic glutamate (mGluR) and β2-adreneric
(β2AR) GPCRs. Inclusion of protein flexibility identifies
regions of the binding pockets not accessible in crystal conformations
and allows for better quantitative estimates of relative ligand binding
affinities in all the proteins tested. Differences in functional group
requirements of the active and inactive states of the β2AR LBP were used in virtual screening to identify high efficacy
agonists targeting β2AR in Airway Smooth Muscle (ASM)
cells. Seven of the 15 selected ligands were found to effect ASM relaxation
representing a 46% hit rate. Hence, the method will be of use for
the rational design of ligands in the context of chemical biology
and the development of therapeutic agents.
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Affiliation(s)
| | | | | | | | | | - Deepak A Deshpande
- §Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, 1020 Locust Street, Philadelphia, Pennsylvania 19107, United States
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15
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Chen J, Campbell AP, Urmi KF, Wakelin LPG, Denny WA, Griffith R, Finch AM. Human α1-adrenoceptor subtype selectivity of substituted homobivalent 4-aminoquinolines. Bioorg Med Chem 2014; 22:5910-6. [PMID: 25288493 DOI: 10.1016/j.bmc.2014.09.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2014] [Revised: 09/01/2014] [Accepted: 09/09/2014] [Indexed: 11/27/2022]
Abstract
A series of ring-substituted ethyl- and heptyl-linked 4-aminoquinoline dimers were synthesized and evaluated for their affinities at the 3 human α(1)-adrenoceptor (α(1)-AR) subtypes and the human serotonin 5-HT(1A)-receptor (5-HT(1A)-R). We find that the structure-specificity profiles are different for the two series at the α(1)-AR subtypes, which suggests that homobivalent 4-aminoquinolines can be developed with α(1)-AR subtype selectivity. The 8-methyl (8-Me) ethyl-linked analogue has the highest affinity for the α(1A)-AR, 7 nM, and the greatest capacity for discriminating between α(1A)-AR and α(1B)-AR (6-fold), α(1D)-AR (68-fold), and the 5-HT(1A)-R (168-fold). α(1B)-AR selectivity was observed with the 6-methyl (6-Me) derivative of the ethyl- and heptyl-linked 4-aminoquinoline dimers and the 7-methoxy (7-OMe) derivative of the heptyl-linked analogue. These substitutions result in 4- to 80-fold selectivity for α(1B)-AR over α(1A)-AR, α(1D)-AR, and 5-HT(1A)-R. In contrast, 4-aminoquinoline dimers with selectivity for α(1D)-AR are more elusive, since none studied to date has greater affinity for the α(1D)-AR over the other two α(1)-ARs. The selectivity of the 8-Me ethyl-linked 4-aminoquinoline dimer for the α(1A)-AR, and 6-Me ethyl-linked, and the 6-Me and 7-OMe heptyl-linked 4-aminoquinoline dimers for the α(1B)-AR, makes them promising leads for drug development of α(1A)-AR or α(1B)-AR subtype selective ligands with reduced 5-HT(1A)-R affinity.
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Affiliation(s)
- Junli Chen
- Department of Pharmacology, School of Medical Sciences, Wallace Wurth Building, UNSW Australia, Sydney, NSW 2052, Australia.
| | - Adrian P Campbell
- Department of Pharmacology, School of Medical Sciences, Wallace Wurth Building, UNSW Australia, Sydney, NSW 2052, Australia.
| | - Kaniz F Urmi
- Department of Pharmacology, School of Medical Sciences, Wallace Wurth Building, UNSW Australia, Sydney, NSW 2052, Australia.
| | - Laurence P G Wakelin
- Department of Pharmacology, School of Medical Sciences, Wallace Wurth Building, UNSW Australia, Sydney, NSW 2052, Australia.
| | - William A Denny
- Auckland Cancer Society Research Centre, School of Medical Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
| | - Renate Griffith
- Department of Pharmacology, School of Medical Sciences, Wallace Wurth Building, UNSW Australia, Sydney, NSW 2052, Australia.
| | - Angela M Finch
- Department of Pharmacology, School of Medical Sciences, Wallace Wurth Building, UNSW Australia, Sydney, NSW 2052, Australia.
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Baker JG, Proudman RGW, Hill SJ. Salmeterol's extreme β2 selectivity is due to residues in both extracellular loops and transmembrane domains. Mol Pharmacol 2014; 87:103-20. [PMID: 25324048 DOI: 10.1124/mol.114.095364] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Salmeterol is a long-acting β2-agonist, widely used as an inhaled treatment of asthma and chronic obstructive pulmonary disease. It has very high β2-affinity (log KD -8.95) and is very selective for the β2-adrenoceptor (1000-fold selectivity over the β1-adrenoceptor). This study used a mutagenesis approach to determine the exact amino acids in the human β2-adrenoceptor responsible for this very high selectivity. Wild-type β2- and β1-adrenoceptors, chimeric β2/β1-adrenoceptors, and receptors with single-point mutations were transfected into Chinese hamster ovary-K1 cells, and affinity and function were studied using [(3)H]CGP 12177 [(-)-4-(3-tert-butylamino-2-hydroxypropoxy)-benzimidazol-2-one] whole-cell binding and [(3)H]cAMP accumulation. Extracellular loop 3 (and specifically amino acid K305) had the largest single effect by reducing salmeterol's affinity for the β2-adrenoceptor by 31-fold. H296 in transmembrane 6 also had a major effect (18-fold reduction in salmeterol affinity). Combining these, in the double mutant β2-H296K-K305D, reduced salmeterol's affinity by 275-fold, to within 4-fold of that of the β1-adrenoceptor, without affecting the affinity or selectivity of other β2-agonists (salbutamol, formoterol, fenoterol, clenbuterol, or adrenaline). Another important amino acid was Y308 in transmembrane 7, although this also affected the affinity and selectivity of other agonists. F194 in extracellular loop 2 and R304 in extracellular loop 3 also had minor effects. None of these mutations (including the double mutant β2-H296K-K305D) affected the efficacy or duration of action of salmeterol. This suggests that the high affinity and selectivity of salmeterol are due to specific amino acids within the receptor itself, but that the duration of action is at least in part due to other factors, for example lipophilicity.
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Affiliation(s)
- Jillian G Baker
- Cell Signalling, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Richard G W Proudman
- Cell Signalling, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Stephen J Hill
- Cell Signalling, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, United Kingdom
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17
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Reese EA, Norimatsu Y, Grandy MS, Suchland KL, Bunzow JR, Grandy DK. Exploring the determinants of trace amine-associated receptor 1's functional selectivity for the stereoisomers of amphetamine and methamphetamine. J Med Chem 2014; 57:378-90. [PMID: 24354319 DOI: 10.1021/jm401316v] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Amphetamines are widely abused drugs that interfere with dopamine transport and storage. Recently, however, another mechanism of action was identified: stereoselective activation of the GαS protein-coupled trace amine-associated receptor 1 (TAAR1). To identify structural determinants of this stereoselectivity, we functionally evaluated six mutant receptors in vitro and then used homology modeling and dynamic simulation to predict drug affinities. Converting Asp102 to Ala rendered mouse and rat TAAR1 (mTAAR1 and rTAAR1, respectively) insensitive to β-phenylethylamine, amphetamine (AMPH), and methamphetamine (METH). Mutating Met268 in rTAAR1 to Thr shifted the concentration-response profiles for AMPH and METH isomers rightward an order of magnitude, whereas replacing Thr268 with Met in mTAAR1 resulted in profiles leftward shifted 10-30-fold. Replacing Asn287 with Tyr in rTAAR1 produced a mouselike receptor, while the reciprocal mTAAR1 mutant was rTAAR1-like. These results confirm TAAR1 is an AMPH/METH receptor in vitro and establish residues 102 (3.32) and 268 (6.55) as major contributors to AMPH/METH binding with residue 287 (7.39) determining species stereoselectivity.
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Affiliation(s)
- Edmund A Reese
- Department of Physiology & Pharmacology, School of Medicine, Oregon Health & Science University , Portland, Oregon 97239, United States
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18
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Mondal S, Khelashvili G, Johner N, Weinstein H. How the dynamic properties and functional mechanisms of GPCRs are modulated by their coupling to the membrane environment. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 796:55-74. [PMID: 24158801 DOI: 10.1007/978-94-007-7423-0_4] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Experimental observations of the dependence of function and organization of G protein-coupled receptors (GPCRs) on their lipid environment have stimulated new quantitative studies of the coupling between the proteins and the membrane. It is important to develop such a quantitative understanding at the molecular level because the effects of the coupling are seen to be physiologically and clinically significant. Here we review findings that offer insight into how membrane-GPCR coupling is connected to the structural characteristics of the GPCR, from sequence to 3D structural detail, and how this coupling is involved in the actions of ligands on the receptor. The application of a recently developed computational approach designed for quantitative evaluation of membrane remodeling and the energetics of membrane-protein interactions brings to light the importance of the radial asymmetry of the membrane-facing surface of GPCRs in their interaction with the surrounding membrane. As the radial asymmetry creates adjacencies of hydrophobic and polar residues at specific sites of the GPCR, the ability of membrane remodeling to achieve complete hydrophobic matching is limited, and the residual mismatch carries a significant energy cost. The adjacencies are shown to be affected by ligand-induced conformational changes. Thus, functionally important organization of GPCRs in the cell membrane can depend both on ligand-determined properties and on the lipid composition of various membrane regions with different remodeling capacities. That this functionally important reorganization can be driven by oligomerization patterns that reduce the energy cost of the residual mismatch, suggests a new perspective on GPCR dimerization and ligand-GPCR interactions. The relation between the modulatory effects on GPCRs from the binding of specific cell-membrane components, e.g., cholesterol, and those produced by the non-local energetics of hydrophobic mismatch are discussed in this context.
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Affiliation(s)
- Sayan Mondal
- Department of Physiology and Biophysics, Weill Cornell Medical College, Cornell University, Room E-509, 1300 York Avenue, 10065, New York City, NY, USA
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20
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Maïga A, Merlin J, Marcon E, Rouget C, Larregola M, Gilquin B, Fruchart-Gaillard C, Lajeunesse E, Marchetti C, Lorphelin A, Bellanger L, Summers RJ, Hutchinson DS, Evans BA, Servent D, Gilles N. Orthosteric binding of ρ-Da1a, a natural peptide of snake venom interacting selectively with the α1A-adrenoceptor. PLoS One 2013; 8:e68841. [PMID: 23935897 PMCID: PMC3723878 DOI: 10.1371/journal.pone.0068841] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Accepted: 06/01/2013] [Indexed: 01/02/2023] Open
Abstract
ρ-Da1a is a three-finger fold toxin from green mamba venom that is highly selective for the α1A-adrenoceptor. This toxin has atypical pharmacological properties, including incomplete inhibition of 3H-prazosin or 125I-HEAT binding and insurmountable antagonist action. We aimed to clarify its mode of action at the α1A-adrenoceptor. The affinity (pKi 9.26) and selectivity of ρ-Da1a for the α1A-adrenoceptor were confirmed by comparing binding to human adrenoceptors expressed in eukaryotic cells. Equilibrium and kinetic binding experiments were used to demonstrate that ρ-Da1a, prazosin and HEAT compete at the α1A-adrenoceptor. ρ-Da1a did not affect the dissociation kinetics of 3H-prazosin or 125I-HEAT, and the IC50 of ρ-Da1a, determined by competition experiments, increased linearly with the concentration of radioligands used, while the residual binding by ρ-Da1a remained stable. The effect of ρ-Da1a on agonist-stimulated Ca2+ release was insurmountable in the presence of phenethylamine- or imidazoline-type agonists. Ten mutations in the orthosteric binding pocket of the α1A-adrenoceptor were evaluated for alterations in ρ-Da1a affinity. The D1063.32A and the S1885.42A/S1925.46A receptor mutations reduced toxin affinity moderately (6 and 7.6 times, respectively), while the F862.64A, F2886.51A and F3127.39A mutations diminished it dramatically by 18- to 93-fold. In addition, residue F862.64 was identified as a key interaction point for 125I-HEAT, as the variant F862.64A induced a 23-fold reduction in HEAT affinity. Unlike the M1 muscarinic acetylcholine receptor toxin MT7, ρ-Da1a interacts with the human α1A-adrenoceptor orthosteric pocket and shares receptor interaction points with antagonist (F862.64, F2886.51 and F3127.39) and agonist (F2886.51 and F3127.39) ligands. Its selectivity for the α1A-adrenoceptor may result, at least partly, from its interaction with the residue F862.64, which appears to be important also for HEAT binding.
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Affiliation(s)
- Arhamatoulaye Maïga
- Commissariat à l'énergie atomique et aux énergies alternatives, iBiTec-S, Service d'Ingénierie Moléculaire des Protéines, Gif sur Yvette, France
| | - Jon Merlin
- Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Elodie Marcon
- Commissariat à l'énergie atomique et aux énergies alternatives, iBiTec-S, Service d'Ingénierie Moléculaire des Protéines, Gif sur Yvette, France
| | - Céline Rouget
- Commissariat à l'énergie atomique et aux énergies alternatives, iBiTec-S, Service d'Ingénierie Moléculaire des Protéines, Gif sur Yvette, France
| | - Maud Larregola
- Commissariat à l'énergie atomique et aux énergies alternatives, iBiTec-S, Service d'Ingénierie Moléculaire des Protéines, Gif sur Yvette, France
| | - Bernard Gilquin
- Commissariat à l'énergie atomique et aux énergies alternatives, iBiTec-S, Service de Bioénergétique, Biologie Structurale et Mécanismes, Gif sur Yvette, France
| | - Carole Fruchart-Gaillard
- Commissariat à l'énergie atomique et aux énergies alternatives, iBiTec-S, Service d'Ingénierie Moléculaire des Protéines, Gif sur Yvette, France
| | - Evelyne Lajeunesse
- Commissariat à l'énergie atomique et aux énergies alternatives, iBiTec-S, Service d'Ingénierie Moléculaire des Protéines, Gif sur Yvette, France
| | - Charles Marchetti
- Commissariat à l'énergie atomique et aux énergies alternatives, iBEB, Service de Biochimie et Toxicologie Nucléaire, Bagnols-sur-Cèze Cedex, France
| | - Alain Lorphelin
- Commissariat à l'énergie atomique et aux énergies alternatives, iBEB, Service de Biochimie et Toxicologie Nucléaire, Bagnols-sur-Cèze Cedex, France
| | - Laurent Bellanger
- Commissariat à l'énergie atomique et aux énergies alternatives, iBEB, Service de Biochimie et Toxicologie Nucléaire, Bagnols-sur-Cèze Cedex, France
| | - Roger J. Summers
- Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Dana S. Hutchinson
- Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Bronwyn A. Evans
- Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Denis Servent
- Commissariat à l'énergie atomique et aux énergies alternatives, iBiTec-S, Service d'Ingénierie Moléculaire des Protéines, Gif sur Yvette, France
| | - Nicolas Gilles
- Commissariat à l'énergie atomique et aux énergies alternatives, iBiTec-S, Service d'Ingénierie Moléculaire des Protéines, Gif sur Yvette, France
- * E-mail:
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Cho DI, Min C, Jung KS, Cheong SY, Zheng M, Cheong SJ, Oak MH, Cheong JH, Lee BK, Kim KM. The N-terminal region of the dopamine D2 receptor, a rhodopsin-like GPCR, regulates correct integration into the plasma membrane and endocytic routes. Br J Pharmacol 2012; 166:659-75. [PMID: 22117524 DOI: 10.1111/j.1476-5381.2011.01787.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND AND PURPOSE Functional roles of the N-terminal region of rhodopsin-like GPCR family remain unclear. Using dopamine D(2) and D(3) receptors as a model system, we probed the roles of the N-terminal region in the signalling, intracellular trafficking of receptor proteins, and explored the critical factors that determine the functionality of the N-terminal region. EXPERIMENTAL APPROACH The N-terminal region of the D(2) receptor was gradually shortened or switched with that of the D(3) receptor or a non-specific sequence (FLAG), or potential N-terminal glycosylation sites were mutated. Effects of these manipulations on surface expression, internalization, post-endocytic behaviours and signalling were determined. KEY RESULTS Shortening the N-terminal region of the D(2) receptor enhanced receptor internalization and impaired surface expression and signalling; ligand binding, desensitization and down-regulation were not affected but their association with a particular microdomain, caveolae, was disrupted. Replacement of critical residues within the N-terminal region with the FLAG epitope failed to restore surface expression but partially restored the altered internalization and signalling. When the N-terminal regions were switched between D(2) and D(3) receptors, cell surface expression pattern of each receptor was switched. Mutations of potential N-terminal glycosylation sites inhibited surface expression but enhanced internalization of D(2) receptors. CONCLUSIONS AND IMPLICATIONS Shortening of N-terminus or mutation of glycosylation sites located within the N-terminus enhanced receptor internalization but impaired the surface expression of D(2) receptors. The N-terminal region of the D(2) receptor, in a sequence-specific manner, controls the receptor's conformation and integration into the plasma membrane, which determine its subcellular localization, intracellular trafficking and signalling properties.
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Affiliation(s)
- D I Cho
- Department of Pharmacology, College of Pharmacy, Research Institute of Drug Development, Chonnam National University, Gwang-Ju, 500-757 Korea
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22
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Jensen PC, Thiele S, Steen A, Elder A, Kolbeck R, Ghosh S, Frimurer TM, Rosenkilde MM. Reversed binding of a small molecule ligand in homologous chemokine receptors - differential role of extracellular loop 2. Br J Pharmacol 2012; 166:258-75. [PMID: 22050085 DOI: 10.1111/j.1476-5381.2011.01771.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE The majority of small molecule compounds targeting chemokine receptors share a similar pharmacophore with a centrally located aliphatic positive charge and flanking aromatic moieties. Here we describe a novel piperidine-based compound with structural similarity to previously described CCR8-specific agonists, but containing a unique phenyl-tetrazol moiety which, in addition to activity at CCR8 was also active at CCR1. EXPERIMENTAL APPROACH Single point mutations were introduced in CCR1 and CCR8, and their effect on small molecule ligand-induced receptor activation was examined through inositol trisphosphate (IP(3) ) accumulation. The molecular interaction profile of the agonist was verified by molecular modeling. KEY RESULTS The chemokine receptor conserved glutamic acid in TM-VII served as a common anchor for the positively charged amine in the piperidine ring. However, whereas the phenyl-tetrazol group interacted with TyrIV:24 (Tyr(172) ) and TyrIII:09 (Tyr(114) ) in the major binding pocket (delimited by TM-III to VII) of CCR8, it also interacted with TrpII:20 (Trp(90) ) and LysII:24 (Lys(94) ) in the minor counterpart (delimited TM-I to III, plus TM-VII) in CCR1. A straightening of TM-II by Ala-substitution of ProII:18 confirmed its unique role in CCR1. The extracellular loop 2 (ECL-2) contributed directly to the small molecule binding site in CCR1, whereas it contributed to efficacy, but not potency in CCR8. CONCLUSION AND IMPLICATIONS Despite high ligand potency and efficacy and receptor similarity, this dual-active and bitopic compound binds oppositely in CCR1 and CCR8 with different roles of ECL-2, thereby expanding and diversifying the influence of extracellular receptor regions in drug action.
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Affiliation(s)
- P C Jensen
- Department of Neuroscience and Pharmacology, Copenhagen University, Copenhagen, Denmark
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23
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Li B, Li W, Du P, Yu KQ, Fu W. Molecular Insights into the D1R Agonist and D2R/D3R Antagonist Effects of the Natural Product (−)-Stepholidine: Molecular Modeling and Dynamics Simulations. J Phys Chem B 2012; 116:8121-30. [DOI: 10.1021/jp3049235] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Bian Li
- Department of Medicinal Chemistry & Key Laboratory of Smart Drug Delivery, Ministry of Education & PLA, School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Wei Li
- Department of Medicinal Chemistry & Key Laboratory of Smart Drug Delivery, Ministry of Education & PLA, School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Peng Du
- Department of Medicinal Chemistry & Key Laboratory of Smart Drug Delivery, Ministry of Education & PLA, School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Kun Qian Yu
- Drug Discovery and Design Center,
State Key Laboratory of Drug Research, Shanghai Institute of Materia
Medica, Chinese Academy of Sciences, Shanghai
201203, China
| | - Wei Fu
- Department of Medicinal Chemistry & Key Laboratory of Smart Drug Delivery, Ministry of Education & PLA, School of Pharmacy, Fudan University, Shanghai 201203, China
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24
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Sanders MPA, Roumen L, van der Horst E, Lane JR, Vischer HF, van Offenbeek J, de Vries H, Verhoeven S, Chow KY, Verkaar F, Beukers MW, McGuire R, Leurs R, Ijzerman AP, de Vlieg J, de Esch IJP, Zaman GJR, Klomp JPG, Bender A, de Graaf C. A prospective cross-screening study on G-protein-coupled receptors: lessons learned in virtual compound library design. J Med Chem 2012; 55:5311-25. [PMID: 22563707 DOI: 10.1021/jm300280e] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
We present the systematic prospective evaluation of a protein-based and a ligand-based virtual screening platform against a set of three G-protein-coupled receptors (GPCRs): the β-2 adrenoreceptor (ADRB2), the adenosine A(2A) receptor (AA2AR), and the sphingosine 1-phosphate receptor (S1PR1). Novel bioactive compounds were identified using a consensus scoring procedure combining ligand-based (frequent substructure ranking) and structure-based (Snooker) tools, and all 900 selected compounds were screened against all three receptors. A striking number of ligands showed affinity/activity for GPCRs other than the intended target, which could be partly attributed to the fuzziness and overlap of protein-based pharmacophore models. Surprisingly, the phosphodiesterase 5 (PDE5) inhibitor sildenafil was found to possess submicromolar affinity for AA2AR. Overall, this is one of the first published prospective chemogenomics studies that demonstrate the identification of novel cross-pharmacology between unrelated protein targets. The lessons learned from this study can be used to guide future virtual ligand design efforts.
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Affiliation(s)
- Marijn P A Sanders
- Computational Drug Discovery Group, Radboud University Nijmegen Medical Centre, Geert Grooteplein, Nijmegen, The Netherlands
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25
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Laurila JMM, Wissel G, Xhaard H, Ruuskanen JO, Johnson MS, Scheinin M. Involvement of the first transmembrane segment of human α(2) -adrenoceptors in the subtype-selective binding of chlorpromazine, spiperone and spiroxatrine. Br J Pharmacol 2012; 164:1558-72. [PMID: 21649638 DOI: 10.1111/j.1476-5381.2011.01520.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Some large antagonist ligands (ARC239, chlorpromazine, prazosin, spiperone, spiroxatrine) bind to the human α(2A) -adrenoceptor with 10- to 100-fold lower affinity than to the α(2B)- and α(2C)-adrenoceptor subtypes. Previous mutagenesis studies have not explained this subtype selectivity. EXPERIMENTAL APPROACH The possible involvement of the extracellular amino terminus and transmembrane domain 1 (TM1) in subtype selectivity was elucidated with eight chimaeric receptors: six where TM1 and the N-terminus were exchanged between the α(2)-adrenoceptor subtypes and two where only TM1 was exchanged. Receptors were expressed in CHO cells and tested for ligand binding with nine chemically diverse antagonist ligands. For purposes of interpretation, molecular models of the three human α(2)-adrenoceptors were constructed based on the β(2)-adrenoceptor crystal structure. KEY RESULTS The affinities of three antagonists (spiperone, spiroxatrine and chlorpromazine) were significantly improved by TM1 substitutions of the α(2A)-adrenoceptor, but reciprocal effects were not seen for chimaeric receptors based on α(2B)- and α(2C)-adrenoceptors. Molecular docking of these ligands suggested that binding occurs in the orthosteric ligand binding pocket. CONCLUSIONS AND IMPLICATIONS TM1 is involved in determining the low affinity of some antagonist ligands at the human α(2A)-adrenoceptor. The exact mechanism is not known, but the position of TM1 at a large distance from the binding pocket indicates that TM1 does not participate in specific side-chain interactions with amino acids within the binding pocket of the receptor or with ligands bound therein. Instead, molecular models suggest that TM1 has indirect conformational effects related to the charge distribution or overall shape of the binding pocket.
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Affiliation(s)
- J M M Laurila
- Department of Pharmacology, Drug Development and Therapeutics, University of Turku, Turku, Finland
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26
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Benned-Jensen T, Smethurst C, Holst PJ, Page KR, Sauls H, Sivertsen B, Schwartz TW, Blanchard A, Jepras R, Rosenkilde MM. Ligand modulation of the Epstein-Barr virus-induced seven-transmembrane receptor EBI2: identification of a potent and efficacious inverse agonist. J Biol Chem 2011; 286:29292-29302. [PMID: 21673108 PMCID: PMC3190735 DOI: 10.1074/jbc.m110.196345] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Revised: 06/10/2011] [Indexed: 12/20/2022] Open
Abstract
The Epstein-Barr virus-induced receptor 2 (EBI2) is a constitutively active seven-transmembrane receptor, which was recently shown to orchestrate the positioning of B cells in the follicle. To date, no ligands, endogenously or synthetic, have been identified that modulate EBI2 activity. Here we describe an inverse agonist, GSK682753A, which selectively inhibited the constitutive activity of EBI2 with high potency and efficacy. In cAMP-response element-binding protein-based reporter and guanosine 5'-3-O-(thio)triphosphate (GTPγS) binding assays, the potency of this compound was 2.6-53.6 nm, and its inhibitory efficacy was 75%. In addition, we show that EBI2 constitutively activated extracellular signal-regulated kinase (ERK) in a pertussis toxin-insensitive manner. Intriguingly, GSK682753A inhibited ERK phosphorylation, GTPγS binding, and cAMP-response element-binding protein activation with similar potency. Overexpression of EBI2 profoundly potentiated antibody-stimulated ex vivo proliferation of murine B cells compared with WT cells, whereas this was equivalently reduced for EBI2-deficient B cells. Inhibition of EBI2 constitutive activity suppressed the proliferation in all cases. Importantly, the suppression was of much higher potency (32-fold) in WT or EBI2-overexpressing B cells compared with EBI2-deficient counterparts. Finally, we screened GSK682753A against an EBI2 mutant library to determine putative molecular binding determinants in EBI2. We identified Phe(111) at position III:08/3.32 as being crucial for GSK682753A inverse agonism because Ala substitution resulted in a >500-fold decrease in IC(50). In conclusion, we present the first ligand targeting EBI2. In turn, this molecule provides a useful tool for further characterization of EBI2 as well as serving as a potent lead compound.
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Affiliation(s)
- Tau Benned-Jensen
- Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | | | - Peter J Holst
- Department of International Health, Immunology, and Microbiology, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark, and
| | - Kevin R Page
- GlaxoSmithKline, Gunnels Wood Road, Stevenage SG1 2NY, United Kingdom
| | - Howard Sauls
- GlaxoSmithKline, Research Triangle Park, North Carolina 27709
| | - Bjørn Sivertsen
- Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Thue W Schwartz
- Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Andy Blanchard
- GlaxoSmithKline, Gunnels Wood Road, Stevenage SG1 2NY, United Kingdom
| | - Robert Jepras
- GlaxoSmithKline, Gunnels Wood Road, Stevenage SG1 2NY, United Kingdom
| | - Mette M Rosenkilde
- Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark,.
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Analysis of multiple compound-protein interactions reveals novel bioactive molecules. Mol Syst Biol 2011; 7:472. [PMID: 21364574 PMCID: PMC3094066 DOI: 10.1038/msb.2011.5] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Accepted: 01/20/2011] [Indexed: 11/21/2022] Open
Abstract
The authors use machine learning of compound-protein interactions to explore drug polypharmacology and to efficiently identify bioactive ligands, including novel scaffold-hopping compounds for two pharmaceutically important protein families: G-protein coupled receptors and protein kinases. We have demonstrated that machine learning of multiple compound–protein interactions is useful for efficient ligand screening and for assessing drug polypharmacology. This approach successfully identified novel scaffold-hopping compounds for two pharmaceutically important protein families: G-protein-coupled receptors and protein kinases. These bioactive compounds were not detected by existing computational ligand-screening methods in comparative studies. The results of this study indicate that data derived from chemical genomics can be highly useful for exploring chemical space, and this systems biology perspective could accelerate drug discovery processes.
The discovery of novel bioactive molecules advances our systems-level understanding of biological processes and is crucial for innovation in drug development. Perturbations of biological systems by chemical probes provide broader applications not only for analysis of complex systems but also for intentional manipulations of these systems. Nevertheless, the lack of well-characterized chemical modulators has limited their use. Recently, chemical genomics has emerged as a promising area of research applicable to the exploration of novel bioactive molecules, and researchers are currently striving toward the identification of all possible ligands for all target protein families (Wang et al, 2009). Chemical genomics studies have shown that patterns of compound–protein interactions (CPIs) are too diverse to be understood as simple one-to-one events. There is an urgent need to develop appropriate data mining methods for characterizing and visualizing the full complexity of interactions between chemical space and biological systems. However, no existing screening approach has so far succeeded in identifying novel bioactive compounds using multiple interactions among compounds and target proteins. High-throughput screening (HTS) and computational screening have greatly aided in the identification of early lead compounds for drug discovery. However, the large number of assays required for HTS to identify drugs that target multiple proteins render this process very costly and time-consuming. Therefore, interest in using in silico strategies for screening has increased. The most common computational approaches, ligand-based virtual screening (LBVS) and structure-based virtual screening (SBVS; Oprea and Matter, 2004; Muegge and Oloff, 2006; McInnes, 2007; Figure 1A), have been used for practical drug development. LBVS aims to identify molecules that are very similar to known active molecules and generally has difficulty identifying compounds with novel structural scaffolds that differ from reference molecules. The other popular strategy, SBVS, is constrained by the number of three-dimensional crystallographic structures available. To circumvent these limitations, we have shown that a new computational screening strategy, chemical genomics-based virtual screening (CGBVS), has the potential to identify novel, scaffold-hopping compounds and assess their polypharmacology by using a machine-learning method to recognize conserved molecular patterns in comprehensive CPI data sets. The CGBVS strategy used in this study was made up of five steps: CPI data collection, descriptor calculation, representation of interaction vectors, predictive model construction using training data sets, and predictions from test data (Figure 1A). Importantly, step 1, the construction of a data set of chemical structures and protein sequences for known CPIs, did not require the three-dimensional protein structures needed for SBVS. In step 2, compound structures and protein sequences were converted into numerical descriptors. These descriptors were used to construct chemical or biological spaces in which decreasing distance between vectors corresponded to increasing similarity of compound structures or protein sequences. In step 3, we represented multiple CPI patterns by concatenating these chemical and protein descriptors. Using these interaction vectors, we could quantify the similarity of molecular interactions for compound–protein pairs, despite the fact that the ligand and protein similarity maps differed substantially. In step 4, concatenated vectors for CPI pairs (positive samples) and non-interacting pairs (negative samples) were input into an established machine-learning method. In the final step, the classifier constructed using training sets was applied to test data. To evaluate the predictive value of CGBVS, we first compared its performance with that of LBVS by fivefold cross-validation. CGBVS performed with considerably higher accuracy (91.9%) than did LBVS (84.4%; Figure 1B). We next compared CGBVS and SBVS in a retrospective virtual screening based on the human β2-adrenergic receptor (ADRB2). Figure 1C shows that CGBVS provided higher hit rates than did SBVS. These results suggest that CGBVS is more successful than conventional approaches for prediction of CPIs. We then evaluated the ability of the CGBVS method to predict the polypharmacology of ADRB2 by attempting to identify novel ADRB2 ligands from a group of G-protein-coupled receptor (GPCR) ligands. We ranked the prediction scores for the interactions of 826 reported GPCR ligands with ADRB2 and then analyzed the 50 highest-ranked compounds in greater detail. Of 21 commercially available compounds, 11 showed ADRB2-binding activity and were not previously reported to be ADRB2 ligands. These compounds included ligands not only for aminergic receptors but also for neuropeptide Y-type 1 receptors (NPY1R), which have low protein homology to ADRB2. Most ligands we identified were not detected by LBVS and SBVS, which suggests that only CGBVS could identify this unexpected cross-reaction for a ligand developed as a target to a peptidergic receptor. The true value of CGBVS in drug discovery must be tested by assessing whether this method can identify scaffold-hopping lead compounds from a set of compounds that is structurally more diverse. To assess this ability, we analyzed 11 500 commercially available compounds to predict compounds likely to bind to two GPCRs and two protein kinases. Functional assays revealed that nine ADRB2 ligands, three NPY1R ligands, five epidermal growth factor receptor (EGFR) inhibitors, and two cyclin-dependent kinase 2 (CDK2) inhibitors were concentrated in the top-ranked compounds (hit rate=30, 15, 25, and 10%, respectively). We also evaluated the extent of scaffold hopping achieved in the identification of these novel ligands. One ADRB2 ligand, two NPY1R ligands, and one CDK2 inhibitor exhibited scaffold hopping (Figure 4), indicating that CGBVS can use this characteristic to rationally predict novel lead compounds, a crucial and very difficult step in drug discovery. This feature of CGBVS is critically different from existing predictive methods, such as LBVS, which depend on similarities between test and reference ligands, and focus on a single protein or highly homologous proteins. In particular, CGBVS is useful for targets with undefined ligands because this method can use CPIs with target proteins that exhibit lower levels of homology. In summary, we have demonstrated that data mining of multiple CPIs is of great practical value for exploration of chemical space. As a predictive model, CGBVS could provide an important step in the discovery of such multi-target drugs by identifying the group of proteins targeted by a particular ligand, leading to innovation in pharmaceutical research. The discovery of novel bioactive molecules advances our systems-level understanding of biological processes and is crucial for innovation in drug development. For this purpose, the emerging field of chemical genomics is currently focused on accumulating large assay data sets describing compound–protein interactions (CPIs). Although new target proteins for known drugs have recently been identified through mining of CPI databases, using these resources to identify novel ligands remains unexplored. Herein, we demonstrate that machine learning of multiple CPIs can not only assess drug polypharmacology but can also efficiently identify novel bioactive scaffold-hopping compounds. Through a machine-learning technique that uses multiple CPIs, we have successfully identified novel lead compounds for two pharmaceutically important protein families, G-protein-coupled receptors and protein kinases. These novel compounds were not identified by existing computational ligand-screening methods in comparative studies. The results of this study indicate that data derived from chemical genomics can be highly useful for exploring chemical space, and this systems biology perspective could accelerate drug discovery processes.
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Mäki T, Kontula K, Härkönen M. The beta-adrenergic system in man: Physiological and pathophysiological response: Regulation of receptor density and functioning. Scand J Clin Lab Invest 2011. [DOI: 10.1080/00365519009085799] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Abstract
A significant challenge for neuroscientists is to determine how both electrical and chemical signals affect the activity of cells and circuits and how the nervous system subsequently translates that activity into behavior. Remote, bidirectional manipulation of those signals with high spatiotemporal precision is an ideal approach to addressing that challenge. Neuroscientists have recently developed a diverse set of tools that permit such experimental manipulation with varying degrees of spatial, temporal, and directional control. These tools use light, peptides, and small molecules to primarily activate ion channels and G protein-coupled receptors (GPCRs) that in turn activate or inhibit neuronal firing. By monitoring the electrophysiological, biochemical, and behavioral effects of such activation/inhibition, researchers can better understand the links between brain activity and behavior. Here, we review the tools that are available for this type of experimentation. We describe the development of the tools and highlight exciting in vivo data. We focus primarily on designer GPCRs (receptors activated solely by synthetic ligands, designer receptors exclusively activated by designer drugs) and microbial opsins (e.g., channelrhodopsin-2, halorhodopsin, Volvox carteri channelrhodopsin) but also describe other novel techniques that use orthogonal receptors, caged ligands, allosteric modulators, and other approaches. These tools differ in the direction of their effect (activation/inhibition, hyperpolarization/depolarization), their onset and offset kinetics (milliseconds/minutes/hours), the degree of spatial resolution they afford, and their invasiveness. Although none of these tools is perfect, each has advantages and disadvantages, which we describe, and they are all still works in progress. We conclude with suggestions for improving upon the existing tools.
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Affiliation(s)
- Sarah C Rogan
- University of North Carolina School of Medicine, Department of Pharmacology, 120 Mason Farm Rd, Chapel Hill, NC 27514, USA
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Kobilka BK. Structural insights into adrenergic receptor function and pharmacology. Trends Pharmacol Sci 2011; 32:213-8. [PMID: 21414670 DOI: 10.1016/j.tips.2011.02.005] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Revised: 02/09/2011] [Accepted: 02/09/2011] [Indexed: 01/14/2023]
Abstract
It has been over 50years since Sir James Black developed the first beta adrenergic receptor (βAR) blocker to treat heart disease. At that time, the concept of cell surface receptors was relatively new and not widely accepted, and most of the tools currently used to characterize plasma membrane receptors had not been developed. There has been remarkable progress in receptor biology since then, including the development of radioligand binding assays, the biochemical characterization of receptors as discrete membrane proteins, and the cloning of the first G-protein-coupled receptors (GPCRs), which led to the identification of other members of the large family of GPCRs. More recently, progress in GPCR structural biology has led to insights into the three-dimensional structures of βARs in both active and inactive states. Despite all of this progress, the process of developing a drug for a particular GPCR target has become more complex, time-consuming and expensive.
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Affiliation(s)
- Brian K Kobilka
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA 94306, USA.
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Lan TH, Kuravi S, Lambert NA. Internalization dissociates β2-adrenergic receptors. PLoS One 2011; 6:e17361. [PMID: 21364942 PMCID: PMC3043075 DOI: 10.1371/journal.pone.0017361] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Accepted: 01/30/2011] [Indexed: 11/19/2022] Open
Abstract
G protein-coupled receptors (GPCRs) self-associate as dimers or higher-order oligomers in living cells. The stability of associated GPCRs has not been extensively studied, but it is generally thought that these receptors move between the plasma membrane and intracellular compartments as intact dimers or oligomers. Here we show that β(2)-adrenergic receptors (β(2)ARs) that self-associate at the plasma membrane can dissociate during agonist-induced internalization. We use bioluminescence-resonance energy transfer (BRET) to monitor movement of β(2)ARs between subcellular compartments. BRET between β(2)ARs and plasma membrane markers decreases in response to agonist activation, while at the same time BRET between β(2)ARs and endosome markers increases. Energy transfer between β(2)ARs is decreased in a similar manner if either the donor- or acceptor-labeled receptor is mutated to impair agonist binding and internalization. These changes take place over the course of 30 minutes, persist after agonist is removed, and are sensitive to several inhibitors of arrestin- and clathrin-mediated endocytosis. The magnitude of the decrease in BRET between donor- and acceptor-labeled β(2)ARs suggests that at least half of the receptors that contribute to the BRET signal are physically segregated by internalization. These results are consistent with the possibility that β(2)ARs associate transiently with each other in the plasma membrane, or that β(2)AR dimers or oligomers are actively disrupted during internalization.
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Affiliation(s)
- Tien-Hung Lan
- Department of Pharmacology and Toxicology, Georgia Health Sciences University, Augusta, Georgia, United States of America
| | - Sudhakiranmayi Kuravi
- Department of Pharmacology and Toxicology, Georgia Health Sciences University, Augusta, Georgia, United States of America
| | - Nevin A. Lambert
- Department of Pharmacology and Toxicology, Georgia Health Sciences University, Augusta, Georgia, United States of America
- * E-mail:
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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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Crasto CJ. Hydrophobicity profiles in G protein-coupled receptor transmembrane helical domains. ACTA ACUST UNITED AC 2010; 2010:123-133. [PMID: 21984869 DOI: 10.2147/jrlcr.s14437] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The lack of a crystallographically derived structure for all but three G (TP [guanosine triphosphate]-binding) protein-coupled receptor (GPCRs) proteins necessitates the use of computationally derived methods to determine their structures. Computational methodologies allow a mechanistic glimpse into GPCR-ligand interactions at a molecular level to better understand the initial steps leading to a protein's biologic functions, ie, protecting the ligands that activate, deactivate, or inhibit the protein, stabilizing protein structure in the membrane's lipid bilayer, and ensuring that the hydrophilic environment within the GPCR-binding pocket is maintained. Described here is a formalism that quantifies the amphiphilic nature of a helix, by determining the effective hydrophobicity (or hydrophilicity) at specific positions around it. This formalism will enable computational protein modelers to position helices so that the functional aspects of GPCRs are adequately represented in the model. Hydro-Eff®, an online tool, allows users to calculate effective helical hydrophobicities.
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Affiliation(s)
- Chiquito J Crasto
- Division of Research, Department of genetics, University of Alabama at Birmingham, Alabama, UsA
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Farb CR, Chang W, Ledoux JE. Ultrastructural characterization of noradrenergic axons and Beta-adrenergic receptors in the lateral nucleus of the amygdala. Front Behav Neurosci 2010; 4:162. [PMID: 21048893 PMCID: PMC2967335 DOI: 10.3389/fnbeh.2010.00162] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2010] [Accepted: 08/23/2010] [Indexed: 11/13/2022] Open
Abstract
Norepinephrine (NE) is thought to play a key role in fear and anxiety, but its role in amygdala-dependent Pavlovian fear conditioning, a major model for understanding the neural basis of fear, is poorly understood. The lateral nucleus of the amygdala (LA) is a critical brain region for fear learning and regulating the effects of stress on memory. To understand better the cellular mechanisms of NE and its adrenergic receptors in the LA, we used antibodies directed against dopamine beta-hydroxylase (DβH), the synthetic enzyme for NE, or against two different isoforms of the beta-adrenergic receptors (βARs), one that predominately recognizes neurons (βAR 248) and the other astrocytes (βAR 404), to characterize the microenvironments of DβH and βAR. By electron microscopy, most DβH terminals did not make synapses, but when they did, they formed both asymmetric and symmetric synapses. By light microscopy, βARs were present in both neurons and astrocytes. Confocal microscopy revealed that both excitatory and inhibitory neurons express βAR248. By electron microscopy, βAR 248 was present in neuronal cell bodies, dendritic shafts and spines, and some axon terminals and astrocytes. When in dendrites and spines, βAR 248 was frequently concentrated along plasma membranes and at post-synaptic densities of asymmetric (excitatory) synapses. βAR 404 was expressed predominately in astrocytic cell bodies and processes. These astrocytic processes were frequently interposed between unlabeled terminals or ensheathed asymmetric synapses. Our findings provide a morphological basis for understanding ways in which NE may modulate transmission by acting via synaptic or non-synaptic mechanisms in the LA.
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Affiliation(s)
- Claudia R Farb
- Center for Neural Science, New York University New York, NY, USA
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36
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Histamine signalling in Schistosoma mansoni: Immunolocalisation and characterisation of a new histamine-responsive receptor (SmGPR-2). Int J Parasitol 2010; 40:1395-406. [DOI: 10.1016/j.ijpara.2010.04.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Revised: 04/01/2010] [Accepted: 04/05/2010] [Indexed: 11/24/2022]
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Arakawa M, Yanamala N, Upadhyaya J, Halayko A, Klein-Seetharaman J, Chelikani P. The importance of valine 114 in ligand binding in beta(2)-adrenergic receptor. Protein Sci 2010; 19:85-93. [PMID: 19916165 DOI: 10.1002/pro.285] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
G-protein coupled receptors (GPCRs) are transmembrane signaling molecules, with a majority of them performing important physiological roles. beta(2)-Adrenergic receptor (beta(2)-AR) is a well-studied GPCRs that mediates natural responses to the hormones adrenaline and noradrenaline. Analysis of the ligand-binding region of beta(2)-AR using the recently solved high-resolution crystal structures revealed a number of highly conserved amino acids that might be involved in ligand binding. However, detailed structure-function studies on some of these residues have not been performed, and their role in ligand binding remains to be elucidated. In this study, we have investigated the structural and functional role of a highly conserved residue valine 114, in hamster beta(2)-AR by site-directed mutagenesis. We replaced V114 in hamster beta(2)-AR with a number of amino acid residues carrying different functional groups. In addition to the complementary substitutions V114I and V114L, the V114C and V114E mutants also showed significant ligand binding and agonist dependent G-protein activation. However, the V114G, V114T, V114S, and V114W mutants failed to bind ligand in a specific manner. Molecular modeling studies were conducted to interpret these results in structural terms. We propose that the replacement of V114 influences not only the interaction of the ethanolamine side-chains but also the aryl-ring of the ligands tested. Results from this study show that the size and orientation of the hydrophobic residue at position V114 in beta(2)-AR affect binding of both agonists and antagonists, but it does not influence the receptor expression or folding.
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Affiliation(s)
- Makoto Arakawa
- Department of Oral Biology, University of Manitoba, Winnipeg, Manitoba, Canada R3E 0W4
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Hirota N, Yasuda D, Hashidate T, Yamamoto T, Yamaguchi S, Nagamune T, Nagase T, Shimizu T, Nakamura M. Amino acid residues critical for endoplasmic reticulum export and trafficking of platelet-activating factor receptor. J Biol Chem 2009; 285:5931-40. [PMID: 20007715 DOI: 10.1074/jbc.m109.066282] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Several residues are conserved in the transmembrane domains (TMs) of G-protein coupled receptors. Here we demonstrate that a conserved proline, Pro(247), in TM6 of platelet-activating factor receptor (PAFR) is required for endoplasmic reticulum (ER) export and trafficking after agonist-induced internalization. Alanine-substituted mutants of the conserved residues of PAFRs, including P247A, were retained in the ER. Because a PAFR antagonist, Y-24180, acted as a pharmacological chaperone to rescue ER retention, this retention is due to misfolding of PAFR. Methylcarbamyl (mc)-PAF, a PAFR agonist, did not increase the cell surface expression of P247A, even though another ER-retained mutant, D63A, was effectively trafficked. Signaling and accumulation of the receptors in the early endosomes were observed in the mc-PAF-treated P247A-expressing cells, suggesting that P247A was trafficked to the cell surface by mc-PAF, and thereafter disappeared from the surface due to aberrant trafficking, e.g. enhanced internalization, deficiency in recycling, and/or accelerated degradation. The aberrant trafficking was confirmed with a sortase-A-mediated method for labeling cell surface proteins. These results demonstrate that the conserved proline in TM6 is crucial for intracellular trafficking of PAFR.
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Affiliation(s)
- Nobuaki Hirota
- Department of Biochemistry and Molecular Biology, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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Hossain M, Ahmed M, Bhuiyan MA, Ishiguro M, Nakamura T, Ozaki M, Nagatomo T. Mutation of important amino acid residue of Asp104Lys in human beta(1)-adrenergic receptor triggers functional and constitutive inactivation. Biol Pharm Bull 2008; 31:1517-22. [PMID: 18670082 DOI: 10.1248/bpb.31.1517] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Based on our previous molecular modeling and radioligand binding study, we have demonstrated that aspartic acid of 104 in transmembrane helix (TMH) II of beta(1)-adrenergic receptor (beta(1)-AR) is important for functional characteristics of these receptors. We have also showed that mutation of negatively charged aspartic acid to neutral charged alanine exhibited constitutive activity of beta(1)-AR. However, the mutation of negatively charged aspartic acid to positively charged lysine is still remained to be examined, which is very important to know for fully understanding the characteristics of beta(1)-AR. At the present study, we mutated aspartic acid to lysine (Asp104Lys) residue in human beta(1)-AR. This resultant mutant (Asp104Lys) markedly reduced the binding affinity of isoproterenol and (-)-epinephrine. On the other hand, antagonist binding with this mutant was similar to the wild type receptor. Isoproterenol at its saturation concentrations produced lower amount of intracellular cyclic adenosine-3',5' cyclic monophosphate (cAMP) in HEK-293 cells expressing Asp104Lys mutant receptor as compared to cells expressing wild type receptor. Moreover, cAMP accumulation of Asp104Lys mutant was unchanged in the presence or absence of isoproterenol. Therefore, it has been demonstrated that Asp104Lys mutation in the human beta(1)-AR differentially affects the binding of antagonist and exhibits a functional uncoupling of G-protein-coupled receptors. Thus, we may suggest that mutation of negatively charged aspartic acid to positively charged lysine as well as neutral charged alanine may help to understand the mechanism of the activation or inactivation of beta(1)-AR by its conformational changes and this finding would be helpful for clarifying the functional responses mediated by beta(1)-AR.
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Affiliation(s)
- Murad Hossain
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Niigata, Japan
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Huber T, Menon S, Sakmar TP. Structural basis for ligand binding and specificity in adrenergic receptors: implications for GPCR-targeted drug discovery. Biochemistry 2008; 47:11013-23. [PMID: 18821775 DOI: 10.1021/bi800891r] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Crystal structures of engineered human beta 2-adrenergic receptors (ARs) in complex with an inverse agonist ligand, carazolol, provide three-dimensional snapshots of the disposition of seven transmembrane helices and the ligand-binding site of an important G protein-coupled receptor (GPCR). As expected, beta 2-AR shares substantial structural similarities with rhodopsin, the dim-light photoreceptor of the rod cell. However, although carazolol and the 11- cis-retinylidene moiety of rhodopsin are situated in the same general binding pocket, the second extracellular (E2) loop structures are quite distinct. E2 in rhodopsin shows beta-sheet structure and forms part of the chromophore-binding site. In the beta 2-AR, E2 is alpha-helical and seems to be distinct from the receptor's active site, allowing a potential entry pathway for diffusible ligands. The structures, together with extensive structure-activity relationship (SAR) data from earlier studies, provide insight about possible structural determinants of ligand specificity and how the binding of agonist ligands might alter receptor conformation. We review key features of the new beta 2-AR structures in the context of recent complementary work on the conformational dynamics of GPCRs. We also report 600 ns molecular dynamics simulations that quantified beta 2-AR receptor mobility in a membrane bilayer environment and show how the binding of an agonist ligand, adrenaline (epinephrine), causes conformational changes to the ligand-binding pocket and neighboring helices.
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Affiliation(s)
- Thomas Huber
- Laboratory of Molecular Biology and Biochemistry, The Rockefeller University, 1230 York Avenue, New York, New York 10065, USA.
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de Graaf C, Rognan D. Selective structure-based virtual screening for full and partial agonists of the beta2 adrenergic receptor. J Med Chem 2008; 51:4978-85. [PMID: 18680279 DOI: 10.1021/jm800710x] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The recently solved high-resolution X-ray structure of the beta2 adrenergic receptor has been challenged for its ability to discriminate inverse agonists/antagonists from partial/full agonists. Whereas the X-ray structure of the ground state receptor was unsuitable to distinguish true ligands with different functional effects, modifying this structure to reflect early conformational events in receptor activation led to a receptor model able to selectively retrieve full and partial agonists by structure-based virtual screening. The use of a topological scoring function based on molecular interaction fingerprints was shown to be mandatory to properly rank docking poses and achieve acceptable enrichments for partial and full agonists only.
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Affiliation(s)
- Chris de Graaf
- Bioinformatics of the Drug, Institut Gilbert Laustriat, CNRS UMR 7175-LC1, Université Louis Pasteur Strasbourg, 74 Route du Rhin, 67401 Illkirch, France
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Kaumann AJ, Molenaar P. The low-affinity site of the β1-adrenoceptor and its relevance to cardiovascular pharmacology. Pharmacol Ther 2008; 118:303-36. [DOI: 10.1016/j.pharmthera.2008.03.009] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2008] [Accepted: 03/20/2008] [Indexed: 10/22/2022]
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Agonist binding, agonist affinity and agonist efficacy at G protein-coupled receptors. Br J Pharmacol 2008; 153:1353-63. [PMID: 18223670 DOI: 10.1038/sj.bjp.0707672] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Measurements of affinity and efficacy are fundamental for work on agonists both in drug discovery and in basic studies on receptors. In this review I wish to consider methods for measuring affinity and efficacy at G protein coupled receptors (GPCRs). Agonist affinity may be estimated in terms of the dissociation constant for agonist binding to a receptor using ligand binding or functional assays. It has, however, been suggested that measurements of affinity are always contaminated by efficacy so that it is impossible to separate the two parameters. Here I show that for many GPCRs, if receptor/G protein coupling is suppressed, experimental measurements of agonist affinity using ligand binding (K(obs)) provide quite accurate measures of the agonist microscopic dissociation constant (KA). Also in pharmacological functional studies, good estimates of agonist dissociation constants are possible. Efficacy can be quantitated in several ways based on functional data (maximal effect of the agonist (E(max)), ratio of agonist dissociation constant to concentration of agonist giving half maximal effect in functional assay (K(obs)/EC50), a combined parameter E(max)K(obs)/EC50). Here I show that E(max)K(obs)/EC50 provides the best assessment of efficacy for a range of agonists across the full range of efficacy for full to partial agonists. Considerable evidence now suggests that ligand efficacy may be dependent on the pathway used to assess it. The efficacy of a ligand may, therefore, be multidimensional. It is still, however, necessary to have accurate measures of efficacy in different pathways.
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Ahmed M, Hossain M, Bhuiyan MA, Ishiguro M, Tanaka T, Muramatsu I, Nagatomo T. Mutational Analysis of the .ALPHA.1a-Adrenergic Receptor Binding Pocket of Antagonists by Radioligand Binding Assay. Biol Pharm Bull 2008; 31:598-601. [DOI: 10.1248/bpb.31.598] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
| | - Murad Hossain
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences
| | - Mohiuddin Ahmed Bhuiyan
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences
| | - Masaji Ishiguro
- Department of Chemical Biology, Faculty of Applied Life Sciences, Niigata University of Pharmacy and Applied Life Sciences
| | - Takashi Tanaka
- Division of Pharmacology, Department of Biochemistry and Bioinformative Sciences, School of Medicine, University of Fukui
| | - Ikunobu Muramatsu
- Division of Pharmacology, Department of Biochemistry and Bioinformative Sciences, School of Medicine, University of Fukui
| | - Takafumi Nagatomo
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences
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Nagaoka Y, Ahmed M, Hossain M, Bhuiyan MA, Ishiguro M, Nakamura T, Watanabe M, Nagatomo T. Amino Acids of the Human α1d-Adrenergic Receptor Involved in Antagonist Binding. J Pharmacol Sci 2008; 106:114-20. [DOI: 10.1254/jphs.fp0071412] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Takahashi K, Hossain M, Ahmed M, Bhuiyan MA, Ohnuki T, Nagatomo T. Asp125 and Thr130 in transmembrane domain 3 are major sites of alpha1b-adrenergic receptor antagonist binding. Biol Pharm Bull 2007; 30:1891-4. [PMID: 17917257 DOI: 10.1248/bpb.30.1891] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Site-directed mutagenesis was used to investigate the molecular interactions involved in prazosin binding to the human alpha(1b)-adrenergic receptor (alpha(1b)-AR) receptor. Based on molecular modeling studies, Thr130 and Asp125 in transmembrane region III of the alpha(1b)-AR receptor were found to interact with prazosin. Thr130 and Asp125 were mutated to alanine (Ala) and expressed in HEK293 cells. The radioligand [(3)H]prazosin did not show any binding to Asp125Ala mutant of alpha(1b)-AR. Therefore, it was not possible to find any prazosin affinity to the mutant using the radioligand [(3)H]prazosin. The mutation also abolished phenylephrine-stimulated inositol phosphate (IP) formation of [(3)H]myo-inositol. On the other hand, the Thr130Ala mutant showed reduced binding affinity for [(3)H]prazosin (dissociation constant, K(d) 674.27 pM versus 90.27 pM for the wild-type receptor) and had reduced affinity for both tamsulosin and prazosin (11-fold and 9-fold, respectively). However, the Thr130Ala mutant receptor retained the ability to stimulate the formation of [(3)H]myo-inositol. The results provide direct evidence that Asp125 and Thr130 are responsible for the interactions between alpha(1b)-AR receptor and radioligand [(3)H]prazosin as well as tamsulosin.
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Affiliation(s)
- Kazuya Takahashi
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Aoba, Niigata, Japan
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Rosenbaum DM, Cherezov V, Hanson MA, Rasmussen SGF, Thian FS, Kobilka TS, Choi HJ, Yao XJ, Weis WI, Stevens RC, Kobilka BK. GPCR engineering yields high-resolution structural insights into beta2-adrenergic receptor function. Science 2007; 318:1266-73. [PMID: 17962519 DOI: 10.1126/science.1150609] [Citation(s) in RCA: 1090] [Impact Index Per Article: 64.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The beta2-adrenergic receptor (beta2AR) is a well-studied prototype for heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) that respond to diffusible hormones and neurotransmitters. To overcome the structural flexibility of the beta2AR and to facilitate its crystallization, we engineered a beta2AR fusion protein in which T4 lysozyme (T4L) replaces most of the third intracellular loop of the GPCR ("beta2AR-T4L") and showed that this protein retains near-native pharmacologic properties. Analysis of adrenergic receptor ligand-binding mutants within the context of the reported high-resolution structure of beta2AR-T4L provides insights into inverse-agonist binding and the structural changes required to accommodate catecholamine agonists. Amino acids known to regulate receptor function are linked through packing interactions and a network of hydrogen bonds, suggesting a conformational pathway from the ligand-binding pocket to regions that interact with G proteins.
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Affiliation(s)
- Daniel M Rosenbaum
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
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Rivail L, Chipot C, Maigret B, Bestel I, Sicsic S, Tarek M. Large-scale molecular dynamics of a G protein-coupled receptor, the human 5-HT4 serotonin receptor, in a lipid bilayer. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.theochem.2007.04.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Asher WB, Hoskins SN, Slasor LA, Morris DH, Cook EM, Bautista DL. Two model system of the alpha1A-adrenoceptor docked with selected ligands. J Chem Inf Model 2007; 47:1906-12. [PMID: 17715910 DOI: 10.1021/ci700026v] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this study, we have developed a two model system to mimic the active and inactive states of a G-protein coupled receptor specifically the alpha1A adrenergic receptor. We have docked two agonists, epinephrine (phenylamine type) and oxymetazoline (imidazoline type), as well as two antagonists, prazosin and 5-methylurapidil, into two alpha1A receptor models, active and inactive. The best docking complexes for both agonists had hydrophilic interactions with D106, while neither antagonist did. Prazosin and oxymetazoline had hydrophobic interactions with F308 and F312. We predict from our study that the active state is stabilized by the interaction of F193 with I114, L197, V278, F281, and V282. The active state is further stabilized by the interaction of F312 with L75, V79, and L80. We also predict that the inactive state of the receptor is stabilized by the interaction of F312 with W102, F288, and M292.
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Affiliation(s)
- Wesley B Asher
- Chemistry Department, Eastern Kentucky University, 521 Lancaster Avenue, Richmond, Kentucky 40475, USA
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Laurila JMM, Xhaard H, Ruuskanen JO, Rantanen MJM, Karlsson HK, Johnson MS, Scheinin M. The second extracellular loop of alpha2A-adrenoceptors contributes to the binding of yohimbine analogues. Br J Pharmacol 2007; 151:1293-304. [PMID: 17558432 PMCID: PMC2189838 DOI: 10.1038/sj.bjp.0707330] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND AND PURPOSE Rodent alpha(2A)-adrenoceptors bind the classical alpha(2)-antagonists yohimbine and rauwolscine with lower affinity than the human alpha(2A)-adrenoceptor. A serine-cysteine difference in the fifth transmembrane helix (TM; position 5.43) partially explains this, but all determinants of the interspecies binding selectivity are not known. Molecular models of alpha(2A)-adrenoceptors suggest that the second extracellular loop (XL2) folds above the binding cavity and may participate in antagonist binding. EXPERIMENTAL APPROACH Amino acids facing the binding cavity were identified using molecular models: side chains of residues 5.43 in TM5 and xl2.49 and xl2.51 in XL2 differ between the mouse and human receptors. Reciprocal mutations were made in mouse and human alpha(2A)-adrenoceptors at positions 5.43, xl2.49 and xl2.51, and tested with a set of thirteen chemically diverse ligands in competition binding assays. KEY RESULTS Reciprocal effects on the binding of yohimbine and rauwolscine in human and mouse alpha(2A)-adrenoceptors were observed for mutations at 5.43, xl2.49 and xl2.51. The binding profile of RS-79948-197 was reversed only by the XL2 substitutions. CONCLUSIONS AND IMPLICATIONS Positions 5.43, xl2.49 and xl2.51 are major determinants of the species preference for yohimbine and rauwolscine of the human versus mouse alpha(2A)-adrenoceptors. Residues at positions xl2.49 and xl2.51 determine the binding preference of RS-79948-197 for the human alpha(2A)-adrenoceptor. Thus, XL2 is involved in determining the species preferences of alpha(2A)-adrenoceptors of human and mouse for some antagonists.
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Affiliation(s)
- J M M Laurila
- Department of Pharmacology, Drug Development and Therapeutics, University of Turku, Itäinen Pitkäkatu 4B, FL-20520 Turku, Finland.
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