1
|
Samuel CS, Li Y, Wang Y, Widdop RE. Functional crosstalk between angiotensin receptors (types 1 and 2) and relaxin family peptide receptor 1 (RXFP1): Implications for the therapeutic targeting of fibrosis. Br J Pharmacol 2024; 181:2302-2318. [PMID: 36560925 DOI: 10.1111/bph.16019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 12/15/2022] [Accepted: 12/20/2022] [Indexed: 12/24/2022] Open
Abstract
Class A, rhodopsin-like, G-protein-coupled receptors (GPCRs) are by far the largest class of GPCRs and are integral membrane proteins used by various cells to convert extracellular signals into intracellular responses. Initially, class A GPCRs were believed to function as monomers, but a growing body of evidence has emerged to suggest that these receptors can function as homodimers and heterodimers and can undergo functional crosstalk to influence the actions of agonists or antagonists acting at each receptor. This review will focus on the angiotensin type 1 (AT1) and type 2 (AT2) receptors, as well as the relaxin family peptide receptor 1 (RXFP1), each of which have their unique characteristics but have been demonstrated to undergo some level of interaction when appropriately co-expressed, which influences the function of each receptor. In particular, this receptor functional crosstalk will be discussed in the context of fibrosis, the tissue scarring that results from a failed wound-healing response to injury, and which is a hallmark of chronic disease and related organ dysfunction. LINKED ARTICLES: This article is part of a themed issue Therapeutic Targeting of G Protein-Coupled Receptors: hot topics from the Australasian Society of Clinical and Experimental Pharmacologists and Toxicologists 2021 Virtual Annual Scientific Meeting. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.14/issuetoc.
Collapse
Affiliation(s)
- Chrishan S Samuel
- Cardiovascular Disease Program, Monash Biomedicine Discovery Institute and Department of Pharmacology, Monash University, Clayton, Victoria, Australia
- Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Yifang Li
- Cardiovascular Disease Program, Monash Biomedicine Discovery Institute and Department of Pharmacology, Monash University, Clayton, Victoria, Australia
| | - Yan Wang
- Cardiovascular Disease Program, Monash Biomedicine Discovery Institute and Department of Pharmacology, Monash University, Clayton, Victoria, Australia
| | - Robert E Widdop
- Cardiovascular Disease Program, Monash Biomedicine Discovery Institute and Department of Pharmacology, Monash University, Clayton, Victoria, Australia
| |
Collapse
|
2
|
Bestsennaia E, Maslov I, Balandin T, Alekseev A, Yudenko A, Abu Shamseye A, Zabelskii D, Baumann A, Catapano C, Karathanasis C, Gordeliy V, Heilemann M, Gensch T, Borshchevskiy V. Channelrhodopsin-2 Oligomerization in Cell Membrane Revealed by Photo-Activated Localization Microscopy. Angew Chem Int Ed Engl 2024; 63:e202307555. [PMID: 38226794 DOI: 10.1002/anie.202307555] [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: 06/06/2023] [Revised: 01/03/2024] [Accepted: 01/15/2024] [Indexed: 01/17/2024]
Abstract
Microbial rhodopsins are retinal membrane proteins that found a broad application in optogenetics. The oligomeric state of rhodopsins is important for their functionality and stability. Of particular interest is the oligomeric state in the cellular native membrane environment. Fluorescence microscopy provides powerful tools to determine the oligomeric state of membrane proteins directly in cells. Among these methods is quantitative photoactivated localization microscopy (qPALM) allowing the investigation of molecular organization at the level of single protein clusters. Here, we apply qPALM to investigate the oligomeric state of the first and most used optogenetic tool Channelrhodopsin-2 (ChR2) in the plasma membrane of eukaryotic cells. ChR2 appeared predominantly as a dimer in the cell membrane and did not form higher oligomers. The disulfide bonds between Cys34 and Cys36 of adjacent ChR2 monomers were not required for dimer formation and mutations disrupting these bonds resulted in only partial monomerization of ChR2. The monomeric fraction increased when the total concentration of mutant ChR2 in the membrane was low. The dissociation constant was estimated for this partially monomerized mutant ChR2 as 2.2±0.9 proteins/μm2 . Our findings are important for understanding the mechanistic basis of ChR2 activity as well as for improving existing and developing future optogenetic tools.
Collapse
Affiliation(s)
- Ekaterina Bestsennaia
- Institute of Biological Information Processing 1, IBI-1 (Molecular and Cellular Physiology), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Ivan Maslov
- Dynamic Bioimaging Lab, Advanced Optical Microscopy Centre and the Biomedical Research Institute, Hasselt University, B3590, Diepenbeek, Belgium
- Laboratory for Photochemistry and Spectroscopy, Division for Molecular Imaging and Photonics, Department of Chemistry, KU Leuven, 3001, Leuven, Belgium
| | - Taras Balandin
- Institute of Biological Information Processing 7, IBI-7 (Structural Biochemistry), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Alexey Alekseev
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37075, Göttingen, Germany
| | - Anna Yudenko
- Department of Biomedical Sciences, University Medical Center Groningen, University of Groningen, 9713 AV, Groningen, The Netherlands
| | - Assalla Abu Shamseye
- Institute of Biological Information Processing 1, IBI-1 (Molecular and Cellular Physiology), Forschungszentrum Jülich, 52428, Jülich, Germany
- Institute of Biological Information Processing 7, IBI-7 (Structural Biochemistry), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Dmitrii Zabelskii
- Institute of Biological Information Processing 7, IBI-7 (Structural Biochemistry), Forschungszentrum Jülich, 52428, Jülich, Germany
- European XFEL, 22869, Schenefeld, Germany
| | - Arnd Baumann
- Institute of Biological Information Processing 1, IBI-1 (Molecular and Cellular Physiology), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Claudia Catapano
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, 60438, Frankfurt, Germany
| | - Christos Karathanasis
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, 60438, Frankfurt, Germany
| | - Valentin Gordeliy
- Institute of Biological Information Processing 7, IBI-7 (Structural Biochemistry), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Mike Heilemann
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, 60438, Frankfurt, Germany
| | - Thomas Gensch
- Institute of Biological Information Processing 1, IBI-1 (Molecular and Cellular Physiology), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Valentin Borshchevskiy
- Institute of Biological Information Processing 7, IBI-7 (Structural Biochemistry), Forschungszentrum Jülich, 52428, Jülich, Germany
| |
Collapse
|
3
|
Casadó-Anguera V, Casadó V. Unmasking allosteric binding sites: Novel targets for GPCR drug discovery. Expert Opin Drug Discov 2022; 17:897-923. [PMID: 35649692 DOI: 10.1080/17460441.2022.2085684] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
INTRODUCTION Unexpected non-apparent and hidden allosteric binding sites are non-classical and non-apparent allosteric centers in 3-D X-ray protein structures until orthosteric or allosteric ligands bind to them. The orthosteric center of one protomer that modulates binding centers of the other protomers within an oligomer is also an unexpected allosteric site. Furthermore, another partner protein can also produce these effects, acting as an unexpected allosteric modulator. AREAS COVERED This review summarizes both classical and non-classical allosterism. The authors focus on G protein-coupled receptor (GPCR) oligomers as a paradigm of allosteric molecules. Moreover, they show several examples of unexpected allosteric sites such as hidden allosteric sites in a protomer that appear after the interaction with other molecules and the allosterism exerted between orthosteric sites within GPCR oligomer, emphasizing on the allosteric modulations that can occur between binding sites. EXPERT OPINION The study of these new non-classical allosteric sites will expand the diversity of allosteric control on the function of orthosteric sites within proteins, whether GPCRs or other receptors, enzymes or transporters. Moreover, the design of new drugs targeting these hidden allosteric sites or already known orthosteric sites acting as allosteric sites in protein homo- or hetero-oligomers will increase the therapeutic potential of allosterism.
Collapse
Affiliation(s)
- Verònica Casadó-Anguera
- Laboratory of Molecular Neuropharmacology, Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Universitat de Barcelona, and Institute of Biomedicine of the Universitat de Barcelona, Barcelona, Spain.,Laboratory of Neuropharmacology-Neurophar, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Vicent Casadó
- Laboratory of Molecular Neuropharmacology, Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Universitat de Barcelona, and Institute of Biomedicine of the Universitat de Barcelona, Barcelona, Spain
| |
Collapse
|
4
|
El Khamlichi C, Cobret L, Arrang JM, Morisset-Lopez S. BRET Analysis of GPCR Dimers in Neurons and Non-Neuronal Cells: Evidence for Inactive, Agonist, and Constitutive Conformations. Int J Mol Sci 2021; 22:ijms221910638. [PMID: 34638980 PMCID: PMC8508734 DOI: 10.3390/ijms221910638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 09/24/2021] [Accepted: 09/27/2021] [Indexed: 11/29/2022] Open
Abstract
G-protein-coupled receptors (GPCRs) are dimeric proteins, but the functional consequences of the process are still debated. Active GPCR conformations are promoted either by agonists or constitutive activity. Inverse agonists decrease constitutive activity by promoting inactive conformations. The histamine H3 receptor (H3R) is the target of choice for the study of GPCRs because it displays high constitutive activity. Here, we study the dimerization of recombinant and brain H3R and explore the effects of H3R ligands of different intrinsic efficacy on dimerization. Co-immunoprecipitations and Western blots showed that H3R dimers co-exist with monomers in transfected HEK 293 cells and in rodent brains. Bioluminescence energy transfer (BRET) analysis confirmed the existence of spontaneous H3R dimers, not only in living HEK 293 cells but also in transfected cortical neurons. In both cells, agonists and constitutive activity of the H3R decreased BRET signals, whereas inverse agonists and GTPγS, which promote inactive conformations, increased BRET signals. These findings show the existence of spontaneous H3R dimers not only in heterologous systems but also in native tissues, which are able to adopt a number of allosteric conformations, from more inactive to more active states.
Collapse
Affiliation(s)
- Chayma El Khamlichi
- Centre de Biophysique Moléculaire, CNRS UPR 4301, Université d’Orléans, Rue Charles Sadron, CEDEX 2, 45071 Orléans, France; (C.E.K.); (L.C.)
| | - Laetitia Cobret
- Centre de Biophysique Moléculaire, CNRS UPR 4301, Université d’Orléans, Rue Charles Sadron, CEDEX 2, 45071 Orléans, France; (C.E.K.); (L.C.)
| | - Jean-Michel Arrang
- Centre de Psychiatrie et Neurosciences, 2 ter Rue d’Alésia, 75014 Paris, France;
- Institut de Psychiatrie et Neurosciences de Paris, UMR_S1266 INSERM, Université Paris Descartes, 102 Rue de la Santé, 75014 Paris, France
| | - Séverine Morisset-Lopez
- Centre de Biophysique Moléculaire, CNRS UPR 4301, Université d’Orléans, Rue Charles Sadron, CEDEX 2, 45071 Orléans, France; (C.E.K.); (L.C.)
- Institut de Psychiatrie et Neurosciences de Paris, UMR_S1266 INSERM, Université Paris Descartes, 102 Rue de la Santé, 75014 Paris, France
- Correspondence: ; Tel.: +33-238257858
| |
Collapse
|
5
|
Feuerstein TJ, Schlicker E. β 1-Blockers Enhance Inotropy of Endogenous Catecholamines in Chronic Heart Failure. Front Cardiovasc Med 2021; 8:639562. [PMID: 34179127 PMCID: PMC8220816 DOI: 10.3389/fcvm.2021.639562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 04/19/2021] [Indexed: 11/30/2022] Open
Abstract
Although β1-blockers impressively reduce mortality in chronic heart failure (CHF), there are concerns about negative inotropic effects and worsening of hemodynamics in acute decompensated heart failure. May receptor theory dispel these concerns and confirm clinical practice to use β1-blockers? In CHF, concentrations of catecholamines at the β1-adrenoceptors usually exceed their dissociation constants (KDs). The homodimeric β1-adrenoceptors have a receptor reserve and display negative cooperativity. We considered the binomial distribution of occupied receptor dimers with respect to the interaction of an exogenous β1-blocker and elevated endogenous agonist concentrations > [KDs], corresponding to an elevated sympathetic tone. Modeling based on binomial distribution suggests that despite the presence of a low concentration of the antagonist, the activation of the dimer receptors is higher than that in its absence. Obviously, the antagonist improves the ratio of the dimer receptors with only single agonist activation compared with the dimer receptors with double activation. This leads to increased positive inotropic effects of endogenous catecholamines due to a β1-blocker. To understand the positive inotropic sequels of β1-blockers in CHF is clinically relevant. This article may help to eliminate the skepticism of clinicians about the use of β1-blockers because of their supposed negative inotropic effect, since, on the contrary, a positive inotropic effect can be expected for receptor-theoretical reasons.
Collapse
Affiliation(s)
- Thomas J Feuerstein
- Sektion für Neuroelektronische Systeme, Klinik für Neurochirurgie, Universität Freiburg, Breisgau, Germany.,Freiburg Institute for Advanced Studies, Albert-Ludwigs-Universität Freiburgf and Institut für Pharmakologie und Toxikologie, Universität Bonn, Bonn, Germany
| | - Eberhard Schlicker
- Institut für Pharmakologie und Toxikologie, Universität Bonn, Bonn, Germany
| |
Collapse
|
6
|
Allosteric interactions via the orthosteric ligand binding sites in a constitutive G-protein-coupled receptor homodimer. Pharmacol Res 2020; 166:105116. [PMID: 32783977 DOI: 10.1016/j.phrs.2020.105116] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 07/26/2020] [Accepted: 07/27/2020] [Indexed: 11/23/2022]
Abstract
I interpret some recent data to indicate that co-operative effects take place between the (identical) orthosteric binding sites in a G-protein-coupled receptor dimer. In the current study, the reasonability of this concept was tested by creating a mathematical model. The model is composed of a symmetrical constitutive receptor dimer in which the protomers are able to affect each other allosterically, and it includes binding, receptor activation and signal amplification steps. The model was utilized for analyses of previous data as well as simulations of predicted behaviour. The model demonstrates the behaviour stated in the hypotheses, i.e. even an apparently neutral receptor ligand can allosterically affect agonist binding or receptor activation by binding to the normal orthosteric ligand binding site. Therewith the speculated allosteric action originating from the orthosteric binding site of the dimeric receptor is a realistic possibility. The results of the simulations and curve fitting constitute a reasonable starting point for further studies, and the model can be utilized to design meaningful experiments to investigate these questions.
Collapse
|
7
|
Saito A, Tsuchiya D, Sato S, Okamoto A, Murakami Y, Mizuguchi K, Toh H, Nemoto W. Update of the GRIP web service. J Recept Signal Transduct Res 2020; 40:348-356. [PMID: 32148150 DOI: 10.1080/10799893.2020.1734821] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
G protein-coupled receptors (GPCRs) can form homodimers, heterodimers, or higher-order molecular complexes (oligomers). The reports on the change of functions through the oligomerization have been accumulated. Inhibition of GPCR oligomerization without affecting the protomer's overall structure would clarify the oligomer-specific functions although inhibition experiments are costly and require accurate information about the interface location. Unfortunately, the number of experimentally determined interfaces is limited. The precise prediction of the oligomerization interfaces is, therefore, useful for inhibition experiments to examine the oligomer-specific functions, which would accelerate investigations of the GPCR signaling. However, interface prediction for GPCR oligomerization is difficult because different GPCR subtypes belonging to the same subfamily often use different structural regions as their interfaces. We previously developed a high-performance method to predict the interfaces for GPCR oligomerization, by identifying the conserved surfaces with the sequence and structure information. Then, the structural characteristic of a GPCR structure is regarded to be a thick-tube like conformation that is approximately perpendicular to the membrane plane. Our method had successfully predicted all of the interfaces available on that day. We had launched a web server for our interface prediction of GPCRs (GRIP). We have improved the previous version of GRIP server and enhanced its usability. First, we discarded the approximation of the GPCR structure as the thick-tube-like conformation. This improvement increased the number of structures for the prediction. Second, the FUGUE-based template recommendation service was introduced to facilitate the choice of an appropriate structure for the prediction. The new prediction server is available at http://grip.b.dendai.ac.jp/∼grip/.
Collapse
Affiliation(s)
- Akira Saito
- Division of Life Science and Engineering, School of Science and Engineering, Tokyo Denki University (TDU), Tokyo, Japan
| | - Daiki Tsuchiya
- Division of Life Science and Engineering, School of Science and Engineering, Tokyo Denki University (TDU), Tokyo, Japan
| | | | | | - Yoichi Murakami
- Laboratory of Bioinformatics, National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN), Institute for Protein Research, Osaka University, Osaka, Japan.,Department of Informatics, Tokyo University of Information Sciences, Tokyo, Japan
| | - Kenji Mizuguchi
- Laboratory of Bioinformatics, National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN), Institute for Protein Research, Osaka University, Osaka, Japan
| | - Hiroyuki Toh
- Department of Biomedical Chemistry, School of Science and Technology, Kwansei Gakuin University, Nishinomiya, Japan
| | - Wataru Nemoto
- Division of Life Science and Engineering, School of Science and Engineering, Tokyo Denki University (TDU), Tokyo, Japan.,Department of Life Science and Engineering, Division of Life Science and Engineering, Tokyo Denki University (TDU), Tokyo, Japan
| |
Collapse
|
8
|
Song X, Yu Y, Shen C, Wang Y, Wang N. Dimerization/oligomerization of the extracellular domain of the GLP-1 receptor and the negative cooperativity in its ligand binding revealed by the improved NanoBiT. FASEB J 2020; 34:4348-4368. [PMID: 31970836 DOI: 10.1096/fj.201902007r] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 12/15/2019] [Accepted: 01/12/2020] [Indexed: 12/13/2022]
Abstract
The glucagon-like peptide-1 receptor (GLP-1R), a family B G-protein coupled receptor (GPCR), regulates the insulin secretion following stimulation by ligands. The transmembrane domain (TM) mediates GLP-1R homodimerization, which modulates its ligand binding and signaling. We investigated the possible involvement of the N-terminal extracellular domain (NTD) in dimerization/oligomerization and dimer-associated ligand binding by NanoLuc Binary Technology (NanoBiT). With improved NanoBiT detection using a decreasing substrate concentration, the negative cooperativity of ligand binding to the NTD was confirmed by accelerated dissociation and Scatchard analysis. The dimerization/oligomerization of the isolated NTD was observed by NanoBiT and validated by analytical ultracentrifugation, deriving the comparable dimerization affinity (~105 M-1 ). The NTD was also involved in the dimerization/oligomerization of the full-length GLP-1R with mutated TM4 at the cellular level. In an analysis of the parameters of the NTD binding, the Kd for the probe GLP-1 (7-36, A8G) was similar (6-8 μM) in both the 1:1 binding model and the receptor dimerization model. Compared with GLP-1 and dulaglutide, exenatide showed two-site binding with Ki values of 1.4 pM and 8.7 nM. Our study indicates the involvement of NTD in the GLP-1R dimerization/oligomerization and suggests that further investigations on the role in other family B GPCRs are needed.
Collapse
Affiliation(s)
- Xiaohan Song
- Beijing Key Laboratory of New Drug Mechanisms and Pharmacological Evaluation Study, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P.R. China
| | - Yi Yu
- Beijing Key Laboratory of New Drug Mechanisms and Pharmacological Evaluation Study, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P.R. China
| | - Cangjie Shen
- Beijing Key Laboratory of New Drug Mechanisms and Pharmacological Evaluation Study, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P.R. China
| | - Yubo Wang
- Beijing Key Laboratory of New Drug Mechanisms and Pharmacological Evaluation Study, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P.R. China
| | - Nan Wang
- Beijing Key Laboratory of New Drug Mechanisms and Pharmacological Evaluation Study, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P.R. China
| |
Collapse
|
9
|
Ferré S, Ciruela F, Casadó V, Pardo L. Oligomerization of G protein-coupled receptors: Still doubted? PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2020; 169:297-321. [DOI: 10.1016/bs.pmbts.2019.11.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
|
10
|
SHBG141-161 Domain-Peptide Stimulates GPRC6A-Mediated Response in Leydig and β-Langerhans cell lines. Sci Rep 2019; 9:19432. [PMID: 31857654 PMCID: PMC6923452 DOI: 10.1038/s41598-019-55941-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 09/30/2019] [Indexed: 11/09/2022] Open
Abstract
GPRC6A is acknowledged as a major regulator of energy metabolism and male fertility through the action of undercarboxylated osteocalcin (ucOCN), representing a possible therapeutic target. We recently showed that the sex hormone-binding globulin (SHBG) binds to GPRC6A through the likely involvement of the 141-161 domain. To confirm this model, here we investigated the possible binding and agonist activity of SHBG(141-161) domain-peptide (SHBG141-161) on GPRC6A. The binding of SHBG141-161 to GPRC6A and downstream dissociation from Gαi(GDP) protein was computationally modelled. SHBG141-161 was obtained by solid-phase synthesis, characterized by circular dichroism (CD) and the receptor binding was assessed by displacement of ucOCN on HEK-293 cells transfected with GPRC6A gene. Agonist activity of SHBG141-161 was assessed on Leydig MA-10 and Langerhans β-TC6 cell lines through the GPRC6A-mediated release of testosterone (T) and insulin. SHBG141-161 was predicted to bind to GPRC6A and to reduce the affinity for Gαi(GDP) at computational level. Conformational properties and binding to GPRC6A of the synthetic SHBG141-161 were confirmed by CD and displacement experiments. SHBG141-161 stimulated cell secretion of T and insulin, with dose dependency from 10-13 to 10-11M for T release (respectively P = 0,041 10-13M; P = 0,032 10-12M; P = 0,008 10-11M vs basal) and for 10-12 to 10-10M for insulin (respectively P = 0,041 10-12M; P = 0,007 10-11M; P = 0,047 10-10M; P = 0,045 vs basal). Blockade with anti GPRC6A IgG abolished the response to SHBG141-161, suggesting agonist specificity. SHBG141-161 showed stimulating activity on GPRC6A, representing a template peptide with possible therapeutic use for metabolic and endocrine disorders.
Collapse
|
11
|
Fongang B, Cunningham KA, Rowicka M, Kudlicki A. Coevolution of Residues Provides Evidence of a Functional Heterodimer of 5-HT 2AR and 5-HT 2CR Involving Both Intracellular and Extracellular Domains. Neuroscience 2019; 412:48-59. [PMID: 31158438 PMCID: PMC7299066 DOI: 10.1016/j.neuroscience.2019.05.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 05/02/2019] [Accepted: 05/07/2019] [Indexed: 10/26/2022]
Abstract
Serotonin is a neurotransmitter that plays a role in regulating activities such as sleep, appetite, mood and substance abuse disorders; serotonin receptors 5-HT2AR and 5-HT2CR are active within pathways associated with substance abuse. It has been suggested that 5-HT2AR and 5-HT2CR may form a dimer that affects behavioral processes. Here we study the coevolution of residues in 5-HT2AR and 5-HT2CR to identify potential interactions between residues in both proteins. Coevolution studies can detect protein interactions, and since the thus uncovered interactions are subject to evolutionary pressure, they are likely functional. We assessed the significance of the 5-HT2AR/5-HT2CR interactions using randomized phylogenetic trees and found the coevolution significant (p-value = 0.01). We also discuss how co-expression of the receptors suggests the predicted interaction is functional. Finally, we analyze how several single nucleotide polymorphisms for the 5-HT2AR and 5-HT2CR genes affect their interaction. Our findings are the first to characterize the binding interface of 5-HT2AR/5-HT2CR and indicate a correlation between this interface and location of SNPs in both proteins.
Collapse
MESH Headings
- Animals
- Databases, Genetic
- Evolution, Molecular
- Papio anubis
- Phosphorylation
- Receptor, Serotonin, 5-HT2A/genetics
- Receptor, Serotonin, 5-HT2A/metabolism
- Receptor, Serotonin, 5-HT2C/genetics
- Receptor, Serotonin, 5-HT2C/metabolism
- Transcriptome
Collapse
Affiliation(s)
- Bernard Fongang
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA; Glenn Biggs Institute for Alzheimer's & Neurodegenerative Diseases, UTHSCSA, San Antonio, TX 78229, USA; Department of Biochemistry and Structural Biology, UTHSCSA, San Antonio, TX 78229, USA; Department of Epidemiology and Biostatistics, UTHSCSA, San Antonio, TX 78229, USA.
| | - Kathryn A Cunningham
- Center for Addiction Research and Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Maga Rowicka
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA; Institute for Translational Sciences, University of Texas Medical Branch, Galveston, TX 77555, USA; Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Andrzej Kudlicki
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA; Institute for Translational Sciences, University of Texas Medical Branch, Galveston, TX 77555, USA; Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, TX 77555, USA.
| |
Collapse
|
12
|
Fam BSO, Reales G, Vargas-Pinilla P, Paré P, Viscardi LH, Sortica VA, Felkl AB, de O Franco Á, Lucion AB, Costa-Neto CM, Pissinatti A, Salzano FM, Paixão-Côrtes VR, Bortolini MC. AVPR1b variation and the emergence of adaptive phenotypes in Platyrrhini primates. Am J Primatol 2019; 81:e23028. [PMID: 31318063 DOI: 10.1002/ajp.23028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 05/31/2019] [Accepted: 06/16/2019] [Indexed: 12/14/2022]
Abstract
Platyrrhini (New World monkeys, NWm) are a group of primates characterized by behavioral and reproductive traits that are otherwise uncommon among primates, including social monogamy, direct paternal care, and twin births. As a consequence, the study of Platyrrhine primates is an invaluable tool for the discovery of the genetic repertoire underlying these taxon-specific traits. Recently, high conservation of vasopressin (AVP) sequence, in contrast with high variability of oxytocin (OXT), has been described in NWm. AVP and OXT functions are possible due to interaction with their receptors: AVPR1a, AVPR1b, AVPR2, and OXTR; and the variability in this system is associated with the traits mentioned above. Understanding the variability in the receptors is thus fundamental to understand the function and evolution of the system as a whole. Here we describe the variability of AVPR1b coding region in 20 NWm species, which is well-known to influence behavioral traits such as aggression, anxiety, and stress control in placental mammals. Our results indicate that 4% of AVPR1b sites may be under positive selection and a significant number of sites under relaxed selective constraint. Considering the known role of AVPR1b, we suggest that some of the changes described here for the Platyrrhini may be a part of the genetic repertoire connected with the complex network of neuroendocrine mechanisms of AVP-OXT system in the modulation of the HPA axis. Thus, these changes may have promoted the emergence of social behaviors such as direct paternal care in socially monogamous species that are also characterized by small body size and twin births.
Collapse
Affiliation(s)
- Bibiana S O Fam
- Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Guillermo Reales
- Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.,INAGEMP - Instituto de Genética Médica e Populacional, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Pedro Vargas-Pinilla
- Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Pamela Paré
- Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Lucas H Viscardi
- Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Vinicius A Sortica
- Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Aline B Felkl
- Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Álvaro de O Franco
- Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Aldo B Lucion
- Departamento de Fisiologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Claudio M Costa-Neto
- Departamento de Bioquímica e Imunologia, Faculdade de Medicina, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | | | - Francisco M Salzano
- Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Vanessa R Paixão-Côrtes
- Departamento de Biologia Geral, Instituto de Biologia, Universidade Federal da Bahia, Salvador, Brazil
| | - Maria Cátira Bortolini
- Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| |
Collapse
|
13
|
Pin JP, Kniazeff J, Prézeau L, Liu JF, Rondard P. GPCR interaction as a possible way for allosteric control between receptors. Mol Cell Endocrinol 2019; 486:89-95. [PMID: 30849406 DOI: 10.1016/j.mce.2019.02.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 02/19/2019] [Accepted: 02/20/2019] [Indexed: 12/17/2022]
Abstract
For more than twenty years now, GPCR dimers and larger oligomers have been the subject of intense debates. Evidence for a role of such complexes in receptor trafficking to and from the plasma membrane have been provided. However, one main issue is of course to determine whether or not such a phenomenon can be responsible for an allosteric and reciprocal control (allosteric control) of the subunits. Such a possibility would indeed add to the possible ways a cell integrates various signals targeting GPCRs. Among the large GPCR family, the class C receptors that include mGlu and GABAB receptors, represent excellent models to examine such a possibility as they are mandatory dimers. In the present review, we will report on the observed allosteric interaction between the subunits of class C GPCRs, both mGluRs and GABABRs, and on the structural bases of these interactions. We will then discuss these findings for other GPCR types such as the rhodopsin-like class A receptors. We will show that many of the observations made with class C receptors have also been reported with class A receptors, suggesting that the mechanisms involved in the allosteric control between subunits in GPCR dimers may not be unique to class C GPCRs.
Collapse
Affiliation(s)
- Jean-Philippe Pin
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France.
| | - Julie Kniazeff
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Laurent Prézeau
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Jiang-Feng Liu
- Cellular Signaling Laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Philippe Rondard
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| |
Collapse
|
14
|
Ding C, Leow MKS, Magkos F. Oxytocin in metabolic homeostasis: implications for obesity and diabetes management. Obes Rev 2019; 20:22-40. [PMID: 30253045 PMCID: PMC7888317 DOI: 10.1111/obr.12757] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 07/25/2018] [Accepted: 07/25/2018] [Indexed: 12/20/2022]
Abstract
Oxytocin was once understood solely as a neuropeptide with a central role in social bonding, reproduction, parturition, lactation and appetite regulation. Recent evidence indicates that oxytocin enhances glucose uptake and lipid utilization in adipose tissue and skeletal muscle, suggesting that dysfunction of the oxytocin system could underlie the pathogenesis of insulin resistance and dyslipidaemia. Murine studies revealed that deficiencies in oxytocin signalling and oxytocin receptor expression lead to obesity despite normal food intake, motor activity and increased leptin levels. In addition, plasma oxytocin concentration is notably lower in obese individuals with diabetes, which may suggest an involvement of the oxytocin system in the pathogenesis of cardiometabolic disease. More recently, small scale studies demonstrated that intranasal administration of oxytocin was associated with significant weight loss as well as improvements in insulin sensitivity and pancreatic β-cell responsivity in human subjects. The multi-pronged effects of oxytocin signalling on improving peripheral insulin sensitivity, pancreatic function and lipid homeostasis strongly suggest a role for this system as a therapeutic target in obesity and diabetes management. The complexity of obesity aetiology and the pathogenesis of obesity-related metabolic complications underscore the need for a systems approach to better understand the role of oxytocin in metabolic function.
Collapse
Affiliation(s)
- C Ding
- Clinical Nutrition Research Centre (CNRC), Singapore Institute for Clinical Sciences (SICS), Agency for Science, Technology and Research (A*STAR) and National University Health System, Singapore
| | - M K-S Leow
- Clinical Nutrition Research Centre (CNRC), Singapore Institute for Clinical Sciences (SICS), Agency for Science, Technology and Research (A*STAR) and National University Health System, Singapore.,Department of Endocrinology, Tan Tock Seng Hospital, Singapore.,Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, Singapore.,Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - F Magkos
- Clinical Nutrition Research Centre (CNRC), Singapore Institute for Clinical Sciences (SICS), Agency for Science, Technology and Research (A*STAR) and National University Health System, Singapore.,Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore (NUS), Singapore
| |
Collapse
|
15
|
Casadó-Anguera V, Moreno E, Mallol J, Ferré S, Canela EI, Cortés A, Casadó V. Reinterpreting anomalous competitive binding experiments within G protein-coupled receptor homodimers using a dimer receptor model. Pharmacol Res 2018; 139:337-347. [PMID: 30472462 DOI: 10.1016/j.phrs.2018.11.032] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 11/14/2018] [Accepted: 11/21/2018] [Indexed: 12/01/2022]
Abstract
An increasing number of G protein-coupled receptors (GPCRs) have been reported to be expressed in the plasma membrane as dimers. Since most ligand binding data are currently fitted by classical equations developed only for monomeric receptors, the interpretation of data could be misleading in the presence of GPCR dimers. On the other hand, the equations developed from dimer receptor models assuming the existence of two orthosteric binding sites within the dimeric molecule offer the possibility to directly calculate macroscopic equilibrium dissociation constants for the two sites, an index of cooperativity (DC) that reflects the molecular communication within the dimer and, importantly, a constant of radioligand-competitor allosteric interaction (KDAB) in competitive assays. Here, we provide a practical way to fit competitive binding data that allows the interpretation of apparently anomalous results, such as competition curves that could be either bell-shaped, monophasic or biphasic depending on the assay conditions. The consideration of a radioligand-competitor allosteric interaction allows fitting these curve patterns both under simulation conditions and in real radioligand binding experiments, obtaining competitor affinity parameters closer to the actual values. Our approach is the first that, assuming the formation of receptor homodimers, is able to explain several experimental results previously considered erroneous due to their impossibility to be fitted. We also deduce the radioligand concentration responsible for the conversion of biphasic to monophasic or to bell-shaped curves in competitive radioligand binding assays. In conclusion, bell-shaped curves in competitive binding experiments constitute evidence for GPCR homodimerization.
Collapse
Affiliation(s)
- Verònica Casadó-Anguera
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Spain; Institute of Biomedicine of the University of Barcelona (IBUB), Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona, Av. Diagonal 643, 08028, Barcelona, Spain.
| | - Estefanía Moreno
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Spain; Institute of Biomedicine of the University of Barcelona (IBUB), Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona, Av. Diagonal 643, 08028, Barcelona, Spain.
| | - Josefa Mallol
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Spain; Institute of Biomedicine of the University of Barcelona (IBUB), Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona, Av. Diagonal 643, 08028, Barcelona, Spain.
| | - Sergi Ferré
- National Institute on Drug Abuse, I.R.P., N.I.H., D.H.H.S., Baltimore, MD, 21224, USA.
| | - Enric I Canela
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Spain; Institute of Biomedicine of the University of Barcelona (IBUB), Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona, Av. Diagonal 643, 08028, Barcelona, Spain.
| | - Antoni Cortés
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Spain; Institute of Biomedicine of the University of Barcelona (IBUB), Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona, Av. Diagonal 643, 08028, Barcelona, Spain.
| | - Vicent Casadó
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Spain; Institute of Biomedicine of the University of Barcelona (IBUB), Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona, Av. Diagonal 643, 08028, Barcelona, Spain.
| |
Collapse
|
16
|
An operational model for GPCR homodimers and its application in the analysis of biased signaling. Drug Discov Today 2018; 23:1591-1595. [DOI: 10.1016/j.drudis.2018.04.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 03/28/2018] [Accepted: 04/05/2018] [Indexed: 11/23/2022]
|
17
|
Gurevich VV, Gurevich EV. GPCRs and Signal Transducers: Interaction Stoichiometry. Trends Pharmacol Sci 2018; 39:672-684. [PMID: 29739625 DOI: 10.1016/j.tips.2018.04.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/11/2018] [Accepted: 04/13/2018] [Indexed: 12/12/2022]
Abstract
Until the late 1990s, class A G protein-coupled receptors (GPCRs) were believed to function as monomers. Indirect evidence that they might internalize or even signal as dimers has emerged, along with proof that class C GPCRs are obligatory dimers. Crystal structures of GPCRs and their much larger binding partners were consistent with the idea that two receptors might engage a single G protein, GRK, or arrestin. However, recent biophysical, biochemical, and structural evidence invariably suggests that a single GPCR binds G proteins, GRKs, and arrestins. Here we review existing evidence of the stoichiometry of GPCR interactions with signal transducers and discuss potential biological roles of class A GPCR oligomers, including proposed homo- and heterodimers.
Collapse
Affiliation(s)
- Vsevolod V Gurevich
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA.
| | - Eugenia V Gurevich
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| |
Collapse
|
18
|
Dynamic tuneable G protein-coupled receptor monomer-dimer populations. Nat Commun 2018; 9:1710. [PMID: 29703992 PMCID: PMC5923235 DOI: 10.1038/s41467-018-03727-6] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 03/06/2018] [Indexed: 01/07/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are the largest class of membrane receptors, playing a key role in the regulation of processes as varied as neurotransmission and immune response. Evidence for GPCR oligomerisation has been accumulating that challenges the idea that GPCRs function solely as monomeric receptors; however, GPCR oligomerisation remains controversial primarily due to the difficulties in comparing evidence from very different types of structural and dynamic data. Using a combination of single-molecule and ensemble FRET, double electron–electron resonance spectroscopy, and simulations, we show that dimerisation of the GPCR neurotensin receptor 1 is regulated by receptor density and is dynamically tuneable over the physiological range. We propose a “rolling dimer” interface model in which multiple dimer conformations co-exist and interconvert. These findings unite previous seemingly conflicting observations, provide a compelling mechanism for regulating receptor signalling, and act as a guide for future physiological studies. Evidence suggests oligomerisation of G protein-coupled receptors in membranes, but this is controversial. Here, authors use single-molecule and ensemble FRET, and spectroscopy to show that the neurotensin receptor 1 forms multiple dimer conformations that interconvert - “rolling” interfaces.
Collapse
|
19
|
Hershfinkel M. The Zinc Sensing Receptor, ZnR/GPR39, in Health and Disease. Int J Mol Sci 2018; 19:ijms19020439. [PMID: 29389900 PMCID: PMC5855661 DOI: 10.3390/ijms19020439] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Revised: 01/24/2018] [Accepted: 01/29/2018] [Indexed: 02/07/2023] Open
Abstract
A distinct G-protein coupled receptor that senses changes in extracellular Zn2+, ZnR/GPR39, was found in cells from tissues in which Zn2+ plays a physiological role. Most prominently, ZnR/GPR39 activity was described in prostate cancer, skin keratinocytes, and colon epithelial cells, where zinc is essential for cell growth, wound closure, and barrier formation. ZnR/GPR39 activity was also described in neurons that are postsynaptic to vesicular Zn2+ release. Activation of ZnR/GPR39 triggers Gαq-dependent signaling and subsequent cellular pathways associated with cell growth and survival. Furthermore, ZnR/GPR39 was shown to regulate the activity of ion transport mechanisms that are essential for the physiological function of epithelial and neuronal cells. Thus, ZnR/GPR39 provides a unique target for therapeutically modifying the actions of zinc in a specific and selective manner.
Collapse
Affiliation(s)
- Michal Hershfinkel
- Department of Physiology and Cell Biology and The Zlotowski Center for Neuroscience, Faculty of Health Sciences, POB 653, Ben-Gurion Ave. Ben-Gurion University of the Negev, Beer Sheva 84105, Israel.
| |
Collapse
|
20
|
Billard E, Létourneau M, Hébert TE, Chatenet D. Insight into the role of urotensin II-related peptide tyrosine residue in UT activation. Biochem Pharmacol 2017; 144:100-107. [DOI: 10.1016/j.bcp.2017.08.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 08/03/2017] [Indexed: 12/16/2022]
|
21
|
Pediani JD, Ward RJ, Marsango S, Milligan G. Spatial Intensity Distribution Analysis: Studies of G Protein-Coupled Receptor Oligomerisation. Trends Pharmacol Sci 2017; 39:175-186. [PMID: 29032835 PMCID: PMC5783713 DOI: 10.1016/j.tips.2017.09.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 09/04/2017] [Accepted: 09/14/2017] [Indexed: 02/08/2023]
Abstract
Spatial intensity distribution analysis (SpIDA) is a recently developed approach for determining quaternary structure information on fluorophore-labelled proteins of interest in situ. It can be applied to live or fixed cells and native tissue. Using confocal images, SpIDA generates fluorescence intensity histograms that are analysed by super-Poissonian distribution functions to obtain density and quantal brightness values of the fluorophore-labelled protein of interest. This allows both expression level and oligomerisation state of the protein to be determined. We describe the application of SpIDA to investigate the oligomeric state of G protein-coupled receptors (GPCRs) at steady state and following cellular challenge, and consider how SpIDA may be used to explore GPCR quaternary organisation in pathophysiology and to stratify medicines. GPCRs may exist and function as monomers: however, abundant evidence suggests they can form dimers/oligomers. This concept has implications for drug discovery as it may offer opportunities to modulate the effects of known pharmaceuticals or identify new drug therapies. A variety of approaches have been applied to this issue from traditional biochemical techniques, via resonance energy transfer approaches to recently developed image analysis-based techniques such as SpIDA. This uses mathematical analysis of confocal microscopy images to generate quantal brightness and density information for a fluorophore-tagged receptor. SpIDA can be applied to live or fixed cells and native tissue. SpIDA has been applied to GPCRs from each of the major subfamilies to explore their oligomerisation status at steady state and their regulation by receptor density and ligand binding.
Collapse
Affiliation(s)
- John D Pediani
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Richard J Ward
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Sara Marsango
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Graeme Milligan
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
| |
Collapse
|
22
|
Iglesias A, Cimadevila M, la Fuente RAD, Martí-Solano M, Cadavid MI, Castro M, Selent J, Loza MI, Brea J. Serotonin 2A receptor disulfide bridge integrity is crucial for ligand binding to different signalling states but not for its homodimerization. Eur J Pharmacol 2017; 815:138-146. [PMID: 28899696 DOI: 10.1016/j.ejphar.2017.09.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 08/28/2017] [Accepted: 09/08/2017] [Indexed: 02/06/2023]
Abstract
The serotonin 2A (5-HT2A) receptor is a G-protein coupled receptor (GPCR) with a conserved disulfide bridge formed by Cys148 (transmembrane helix 3, TM3) and Cys227 (extracellular loop 2, ECL-2). We hypothesized that disulfide bridges may determine serotonin 5-HT2A receptor functions such as receptor activation, functional selectivity and ligand recognition. We used the reducing agent dithiothreitol (DTT) to determine how the reduction of disulfide bridges affects radioligand binding, second messenger mobilization and receptor dimerization. A DTT-induced decrease in the number of binding sites (1190 ± 63.55 fmol/mg protein for control cells compared with 921.2 ± 60.84 fmol/mg protein for DTT-treated cells) as well as in the efficacy of both signalling pathways characterized was observed, although the affinity and potency were unchanged. Bioluminiscence resonance energy transfer (BRET) assays revealed the DTT treatment did not modify the homodimeric nature of serotonin 5-HT2A receptors. In molecular dynamic simulations, the ECL-2 of the receptor with a broken cysteine bond adopts a wider variety of conformations, some of which protrude deeper into the receptor orthosteric binding pocket leading to collapse of the pocket. A shrunken binding pocket would be incapable of accommodating lysergic acid diethylamide (LSD). Our findings suggest that the decrease of efficacy may be due to disruption of disulfide bridge between TM3 and ECL-2. This reveals the integrity of the ECL-2 epitope, which should be explored in the development of novel ligands acting as allosteric modulators of serotonin 5-HT2A receptors.
Collapse
Affiliation(s)
- Alba Iglesias
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain
| | - Marta Cimadevila
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain
| | - Rocío Ailim de la Fuente
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain; Molecular Pharmacology of G Protein-coupled Receptors Laboratory, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain
| | - María Martí-Solano
- GPCR Drug Discovery Group, Research Programme on Biomedical Informatics (GRIB), Hospital del Mar Medical Research Institute (IMIM) - Department of Experimental and Health Sciences of Pompeu Fabra University (UPF), Barcelona, Spain
| | - María Isabel Cadavid
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain
| | - Marián Castro
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain; Molecular Pharmacology of G Protein-coupled Receptors Laboratory, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain
| | - Jana Selent
- GPCR Drug Discovery Group, Research Programme on Biomedical Informatics (GRIB), Hospital del Mar Medical Research Institute (IMIM) - Department of Experimental and Health Sciences of Pompeu Fabra University (UPF), Barcelona, Spain
| | - María Isabel Loza
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain.
| | - José Brea
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain.
| |
Collapse
|
23
|
Iglesias A, Cimadevila M, Cadavid MI, Loza MI, Brea J. Serotonin-2A homodimers are needed for signalling via both phospholipase A 2 and phospholipase C in transfected CHO cells. Eur J Pharmacol 2017; 800:63-69. [PMID: 28216047 DOI: 10.1016/j.ejphar.2017.02.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 02/16/2017] [Accepted: 02/16/2017] [Indexed: 01/05/2023]
Abstract
Different ligands differentially activate phospholipase A2 (PLA2) and phospholipase C (PLC) signalling pathways that are coupled to the serotonin 2A (5-HT2A) receptor, a class-A G-protein coupled receptor (GPCR). The serotonin 5-HT2A receptor has been shown to be expressed as a homodimer displaying some ligands negative cooperativity between protomers in the PLA2 signalling pathway. We hypothesized that the homodimeric complex is the minimum functional unit required for activation of the PLA2 and PLC pathways by the serotonin 5-HT2A receptor. To investigate this hypothesis, we partially blocked the serotonin 5-HT2A receptors with ritanserin and measured PLA2 and PLC activity simultaneously. We subsequently added the competitive antagonist spiperone to release the inactivator through a crosstalk mechanism and thus allow the dimer to return to a reactive state. Partial inactivation of the homodimer by ritanserin binding decreased the activity of the receptor by 59±13% and 70±4% in the PLA2 and PLC pathways respectively (P<0.001), with no difference in the potency of the serotonin (5-HT) was observed. The subsequent binding of spiperone released ritanserin due to the crosstalk between protomers and recovery of the receptor activity to 74±7% and 72±4%. Negative cooperativity between protomers in the dimer was maintained during arachidonic acid (AA) release after blocking ritanserin, as indicated by the biphasic inhibition curves for clozapine over 1μM serotonin (5-HT) in these conditions. These findings provide evidence that serotonin 5-HT2A receptors must be expressed as homodimers in order to activate both the PLA2 and PLC signalling pathways.
Collapse
Affiliation(s)
- Alba Iglesias
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CiMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain
| | - Marta Cimadevila
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CiMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain
| | - María Isabel Cadavid
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CiMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain
| | - María Isabel Loza
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CiMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain.
| | - José Brea
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CiMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain.
| |
Collapse
|
24
|
Wan J, Mobli M, Brust A, Muttenthaler M, Andersson Å, Ragnarsson L, Castro J, Vetter I, Huang JX, Nilsson M, Brierley SM, Cooper MA, Lewis RJ, Alewood PF. Synthesis of Multivalent [Lys8]-Oxytocin Dendrimers that Inhibit Visceral Nociceptive Responses. Aust J Chem 2017. [DOI: 10.1071/ch16407] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Peptide dendrimers are a novel class of precisely defined macromolecules of emerging interest. Here, we describe the synthesis, structure, binding affinity, receptor selectivity, functional activity, and antinociceptive properties of oxytocin-related dendrimers containing up to 16 copies of [Lys8]-oxytocin or LVT. These were generated using a copper(i)-catalyzed azide–alkyne cycloaddition (CuAAc) reaction with azido-pegylated LVT peptides on an alkyne–polylysine scaffold. 2D NMR analysis demonstrated that each attached LVT ligand was freely rotating and maintained identical 3D structures in each dendrimeric macromolecule. The binding affinity Ki at the oxytocin receptor increased approximately 17-, 12-, 3-, and 1.5-fold respectively for the 2-, 4-, 8-, and 16-mer dendrimeric LVT conjugates, compared with monomer azido-pegylated LVT (Ki = 9.5 nM), consistent with a multivalency effect. A similar trend in affinity was also observed at the related human V1a, V1b, and V2 receptors, with no significant selectivity change observed across this family of receptors. All LVT dendrimers were functionally active in vitro on human oxytocin receptors and inhibited colonic nociceptors potently in a mouse model of chronic abdominal pain.
Collapse
|
25
|
Busnelli M, Kleinau G, Muttenthaler M, Stoev S, Manning M, Bibic L, Howell LA, McCormick PJ, Di Lascio S, Braida D, Sala M, Rovati GE, Bellini T, Chini B. Design and Characterization of Superpotent Bivalent Ligands Targeting Oxytocin Receptor Dimers via a Channel-Like Structure. J Med Chem 2016; 59:7152-66. [PMID: 27420737 DOI: 10.1021/acs.jmedchem.6b00564] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Dimeric/oligomeric states of G-protein coupled receptors have been difficult to target. We report here bivalent ligands consisting of two identical oxytocin-mimetics that induce a three order magnitude boost in G-protein signaling of oxytocin receptors (OTRs) in vitro and a 100- and 40-fold gain in potency in vivo in the social behavior of mice and zebrafish. Through receptor mutagenesis and interference experiments with synthetic peptides mimicking transmembrane helices (TMH), we show that such superpotent behavior follows from the binding of the bivalent ligands to dimeric receptors based on a TMH1-TMH2 interface. Moreover, in this arrangement, only the analogues with a well-defined spacer length (∼25 Å) precisely fit inside a channel-like passage between the two protomers of the dimer. The newly discovered oxytocin bivalent ligands represent a powerful tool for targeting dimeric OTR in neurodevelopmental and psychiatric disorders and, in general, provide a framework to untangle specific arrangements of G-protein coupled receptor dimers.
Collapse
Affiliation(s)
- Marta Busnelli
- CNR, Institute of Neuroscience , Milan, Italy 20129.,Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano , Milan, Italy 20129
| | - Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin , Berlin, Germany 13353
| | - Markus Muttenthaler
- Institute for Molecular Bioscience, The University of Queensland , Brisbane, Australia 4072
| | - Stoytcho Stoev
- Department of Biochemistry and Cancer Biology, University of Toledo , Toledo, Ohio 43614, United States
| | - Maurice Manning
- Department of Biochemistry and Cancer Biology, University of Toledo , Toledo, Ohio 43614, United States
| | - Lucka Bibic
- School of Pharmacy, University of East Anglia , Norwich Research Park, Norwich, U.K. NR4 7TJ
| | - Lesley A Howell
- School of Pharmacy, University of East Anglia , Norwich Research Park, Norwich, U.K. NR4 7TJ
| | - Peter J McCormick
- School of Pharmacy, University of East Anglia , Norwich Research Park, Norwich, U.K. NR4 7TJ
| | - Simona Di Lascio
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano , Milan, Italy 20129
| | - Daniela Braida
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano , Milan, Italy 20129
| | - Mariaelvina Sala
- CNR, Institute of Neuroscience , Milan, Italy 20129.,Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano , Milan, Italy 20129
| | - G Enrico Rovati
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano , Milan, Italy 20133
| | - Tommaso Bellini
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano , Milan, Italy 20129
| | - Bice Chini
- CNR, Institute of Neuroscience , Milan, Italy 20129
| |
Collapse
|
26
|
Kleinau G, Müller A, Biebermann H. Oligomerization of GPCRs involved in endocrine regulation. J Mol Endocrinol 2016; 57:R59-80. [PMID: 27151573 DOI: 10.1530/jme-16-0049] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 05/04/2016] [Indexed: 12/27/2022]
Abstract
More than 800 different human membrane-spanning G-protein-coupled receptors (GPCRs) serve as signal transducers at biological barriers. These receptors are activated by a wide variety of ligands such as peptides, ions and hormones, and are able to activate a diverse set of intracellular signaling pathways. GPCRs are of central importance in endocrine regulation, which underpins the significance of comprehensively studying these receptors and interrelated systems. During the last decade, the capacity for multimerization of GPCRs was found to be a common and functionally relevant property. The interaction between GPCR monomers results in higher order complexes such as homomers (identical receptor subtype) or heteromers (different receptor subtypes), which may be present in a specific and dynamic monomer/oligomer equilibrium. It is widely accepted that the oligomerization of GPCRs is a mechanism for determining the fine-tuning and expansion of cellular processes by modification of ligand action, expression levels, and related signaling outcome. Accordingly, oligomerization provides exciting opportunities to optimize pharmacological treatment with respect to receptor target and tissue selectivity or for the development of diagnostic tools. On the other hand, GPCR heteromerization may be a potential reason for the undesired side effects of pharmacological interventions, faced with numerous and common mutual signaling modifications in heteromeric constellations. Finally, detailed deciphering of the physiological occurrence and relevance of specific GPCR/GPCR-ligand interactions poses a future challenge. This review will tackle the aspects of GPCR oligomerization with specific emphasis on family A GPCRs involved in endocrine regulation, whereby only a subset of these receptors will be discussed in detail.
Collapse
Affiliation(s)
- Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology (IEPE)Charité-Universitätsmedizin, Berlin, Germany
| | - Anne Müller
- Institute of Experimental Pediatric Endocrinology (IEPE)Charité-Universitätsmedizin, Berlin, Germany
| | - Heike Biebermann
- Institute of Experimental Pediatric Endocrinology (IEPE)Charité-Universitätsmedizin, Berlin, Germany
| |
Collapse
|
27
|
Dual allosteric modulation of opioid antinociceptive potency by α2A-adrenoceptors. Neuropharmacology 2015; 99:285-300. [PMID: 26254859 DOI: 10.1016/j.neuropharm.2015.08.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2014] [Revised: 07/09/2015] [Accepted: 08/04/2015] [Indexed: 12/31/2022]
Abstract
Opioid and α2-adrenoceptor (AR) agonists are analgesic when administered in the spinal cord and show a clinically beneficial synergistic interaction when co-administered. However, α2-AR antagonists can also inhibit opioid antinociception, suggesting a complex interaction between the two systems. The α2A-AR subtype is necessary for spinal adrenergic analgesia and synergy with opioids for most agonist combinations. Therefore, we investigated whether spinal opioid antinociception and opioid-adrenergic synergy were under allosteric control of the α2A-AR. Drugs were administered intrathecally in wild type (WT) and α2A-knock-out (KO) mice and antinociception was measured using the hot water tail immersion or substance P behavioral assays. The α2A-AR agonist clonidine was less effective in α2A-KO mice in both assays. The absence of the α2A-AR resulted in 10-70-fold increases in the antinociceptive potency of the opioid agonists morphine and DeltII. In contrast, neither morphine nor DeltII synergized with clonidine in α2A-KO mice, indicating that the α2AAR has both positive and negative modulatory effects on opioid antinociception. Depletion of descending adrenergic terminals with 6-OHDA resulted in a significant decrease in morphine efficacy in WT but not in α2A-KO mice, suggesting that endogenous norepinephrine acts through the α2A-AR to facilitate morphine antinociception. Based on these findings, we propose a model whereby ligand-occupied versus ligand-free α2A-AR produce distinct patterns of modulation of opioid receptor activation. In this model, agonist-occupied α2A-ARs potentiate opioid analgesia, while non-occupied α2A-ARs inhibit opioid analgesia. Exploiting such interactions between the two receptors could lead to the development of better pharmacological treatments for pain management.
Collapse
|
28
|
Zmora N, Stubblefield JD, Wong TT, Levavi-Sivan B, Millar RP, Zohar Y. Kisspeptin Antagonists Reveal Kisspeptin 1 and Kisspeptin 2 Differential Regulation of Reproduction in the Teleost, Morone saxatilis. Biol Reprod 2015; 93:76. [PMID: 26246220 DOI: 10.1095/biolreprod.115.131870] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 08/03/2015] [Indexed: 11/01/2022] Open
Abstract
The importance of kisspeptin in regulating vertebrate reproduction has been well established, but the exact mechanism continues to unfold. Unlike mammals, many lower vertebrates possess a dual kisspeptin system, Kiss1 and Kiss2. To decipher the roles of the kisspeptins in fish, we identified two potential kisspeptin antagonists, pep 234 and pep 359, by screening analogs for their ability to inactivate striped bass Kiss1 and Kiss2 receptors expressed in COS7 cells. Pep 234 (a mammalian KISS1 antagonist) antagonizes Kiss1r signaling activated by Kiss1 and Kiss2, and pep 359 (a novel analog) antagonizes Kiss2 activation of both receptors. In vitro studies using brain slices demonstrated that only Kiss2 can upregulate the expression of the hypophysiotropic gnrh1, which was subsequently diminished by pep 234 and pep 359. In primary pituitary cell cultures, the two antagonists revealed a complex network of putative endogenous and exogenous regulation by kisspeptin. While both kisspeptins stimulate Fsh expression and secretion, Kiss2 predominately induces Lh secretion. Pep 234 and 359 treatment of spawning males hindered sperm production. This effect was accompanied with decreased brain gnrh1 and gnrh2 mRNA levels and peptide content in the pituitary, and increased levels of pituitary Lh, probably due to attenuation of Lh release. Strikingly, the mRNA levels of arginine-vasotocin, the neurons of which in the preoptic area coexpress kiss2r, were dramatically reduced by the antagonists. Our results demonstrate differential actions of Kiss1 and Kiss2 systems along the hypothalamic-pituitary axis and interactions with other neuropeptides, and further reinforce the importance of kisspeptin in the execution of spawning.
Collapse
Affiliation(s)
- Nilli Zmora
- Insitute of Marine and Environmental Technology, Department of Marine Biotechnology, University of Maryland Baltimore County, Baltimore, Maryland
| | - John David Stubblefield
- Insitute of Marine and Environmental Technology, Department of Marine Biotechnology, University of Maryland Baltimore County, Baltimore, Maryland
| | - Ten-Tsao Wong
- Insitute of Marine and Environmental Technology, Department of Marine Biotechnology, University of Maryland Baltimore County, Baltimore, Maryland
| | - Berta Levavi-Sivan
- Department of Animal Sciences, Faculty of Agriculture, Food and Environment, the Hebrew University, Rehobot, Israel
| | - Robert Peter Millar
- Mammal Research Institute, Department of Zoology, University of Pretoria, Pretoria, South Africa University of Cape Town/Medical Research Council Receptor Biology Unit, Institute for Infectious Diseases and Molecular Medicine, University of Cape Town, Cape Town, South Africa
| | - Yonathan Zohar
- Insitute of Marine and Environmental Technology, Department of Marine Biotechnology, University of Maryland Baltimore County, Baltimore, Maryland
| |
Collapse
|
29
|
Vischer HF, Castro M, Pin JP. G Protein-Coupled Receptor Multimers: A Question Still Open Despite the Use of Novel Approaches. Mol Pharmacol 2015; 88:561-71. [PMID: 26138074 DOI: 10.1124/mol.115.099440] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Accepted: 07/02/2015] [Indexed: 12/11/2022] Open
Abstract
Heteromerization of G protein-coupled receptors (GPCRs) can significantly change the functional properties of involved receptors. Various biochemical and biophysical methodologies have been developed in the last two decades to identify and functionally evaluate GPCR heteromers in heterologous cells, with recent approaches focusing on GPCR complex stoichiometry and stability. Yet validation of these observations in native tissues is still lagging behind for the majority of GPCR heteromers. Remarkably, recent studies, particularly some involving advanced fluorescence microscopy techniques, are contributing to our current knowledge of aspects that were not well known until now, such as GPCR complex stoichiometry and stability. In parallel, a growing effort is being applied to move the field forward into native systems. This short review will highlight recent developments to study the stoichiometry and stability of GPCR complexes and methodologies to detect native GPCR dimers.
Collapse
Affiliation(s)
- Henry F Vischer
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, Amsterdam, The Netherlands (H.F.V.); Molecular Pharmacology Laboratory, Biofarma Research Group (GI-1685), University of Santiago de Compostela, Center for Research in Molecular Medicine and Chronic Diseases, Santiago de Compostela, Spain (M.C.); and Centre National de la Recherche Scientifique, Institut de Génomique Fonctionnelle, Université de Montpellier, Montpellier, France (J.-P.P.)
| | - Marián Castro
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, Amsterdam, The Netherlands (H.F.V.); Molecular Pharmacology Laboratory, Biofarma Research Group (GI-1685), University of Santiago de Compostela, Center for Research in Molecular Medicine and Chronic Diseases, Santiago de Compostela, Spain (M.C.); and Centre National de la Recherche Scientifique, Institut de Génomique Fonctionnelle, Université de Montpellier, Montpellier, France (J.-P.P.)
| | - Jean-Philippe Pin
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, Amsterdam, The Netherlands (H.F.V.); Molecular Pharmacology Laboratory, Biofarma Research Group (GI-1685), University of Santiago de Compostela, Center for Research in Molecular Medicine and Chronic Diseases, Santiago de Compostela, Spain (M.C.); and Centre National de la Recherche Scientifique, Institut de Génomique Fonctionnelle, Université de Montpellier, Montpellier, France (J.-P.P.)
| |
Collapse
|
30
|
Vauquelin G, Hall D, Charlton SJ. 'Partial' competition of heterobivalent ligand binding may be mistaken for allosteric interactions: a comparison of different target interaction models. Br J Pharmacol 2015; 172:2300-15. [PMID: 25537684 DOI: 10.1111/bph.13053] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 10/25/2014] [Accepted: 12/14/2014] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND AND PURPOSE Non-competitive drugs that confer allosteric modulation of orthosteric ligand binding are of increasing interest as therapeutic agents. Sought-after advantages include a ceiling level to drug effect and greater receptor-subtype selectivity. It is thus important to determine the mode of interaction of newly identified receptor ligands early in the drug discovery process and binding studies with labelled orthosteric ligands constitute a traditional approach for this. According to the general allosteric ternary complex model, allosteric ligands that exhibit negative cooperativity may generate distinctive 'competition' curves: they will not reach baseline levels and their nadir will increase in par with the orthosteric ligand concentration. This behaviour is often considered a key hallmark of allosteric interactions. EXPERIMENTAL APPROACH The present study is based on differential equation-based simulations. KEY RESULTS The differential equation-based simulations revealed that the same 'competition binding' pattern was also obtained when a monovalent ligand binds to one of the target sites of a heterobivalent ligand, even if this process is exempt of allosteric interactions. This pattern was not strictly reciprocal when the binding of each of the ligands was recorded. The prominence of this phenomenon may vary from one heterobivalent ligand to another and we suggest that this phenomenon may take place with ligands that have been proposed to bind according to 'two-domain' and 'charnière' models. CONCLUSIONS AND IMPLICATIONS The present findings indicate a familiar experimental situation where bivalency may give rise to observations that could inadvertently be interpreted as allosteric binding. Yet, both mechanisms could be differentiated based on alternative experiments and structural considerations.
Collapse
Affiliation(s)
- Georges Vauquelin
- Department Molecular and Biochemical Pharmacology, Vrije Universiteit Brussel, Brussels, Belgium
| | | | | |
Collapse
|
31
|
Hounsou C, Margathe JF, Oueslati N, Belhocine A, Dupuis E, Thomas C, Mann A, Ilien B, Rognan D, Trinquet E, Hibert M, Pin JP, Bonnet D, Durroux T. Time-resolved FRET binding assay to investigate hetero-oligomer binding properties: proof of concept with dopamine D1/D3 heterodimer. ACS Chem Biol 2015; 10:466-74. [PMID: 25350273 DOI: 10.1021/cb5007568] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
G protein-coupled receptors (GPCRs) have been described to form hetero-oligomers. The importance of these complexes in physiology and pathology is considered crucial, and heterodimers represent promising new targets to discover innovative therapeutics. However, there is a lack of binding assays to allow the evaluation of ligand affinity for GPCR hetero-oligomers. Using dopamine receptors and more specifically the D1 and D3 receptors as GPCR models, we developed a new time-resolved FRET (TR-FRET) based assay to determine ligand affinity for the D1/D3 heteromer. Based on the high-resolution structure of the dopamine D3 receptor (D3R), six fluorescent probes derived from a known D3R partial agonist (BP 897) were designed, synthesized and evaluated as high affinity and selective ligands for the D3/D2 receptors, and for other dopamine receptor subtypes. The highest affinity ligand 21 was then employed in the development of the D1/D3 heteromer assay. The TR-FRET was monitored between a fluorescent tag donor carried by the D1 receptor (D1R) and a fluorescent acceptor D3R ligand 21. The newly reported assay, easy to implement on other G protein-coupled receptors, constitutes an attractive strategy to screen for heteromer ligands.
Collapse
Affiliation(s)
- Candide Hounsou
- CNRS UMR 5203, and INSERM U661, and Université Montpellier I et II, Institut de Génomique Fonctionnelle, Département de Pharmacologie Moléculaire, 141 rue de la Cardonille, 34094 Montpellier Cedex 5, France
| | - Jean-François Margathe
- Laboratoire d’Innovation
Thérapeutique, UMR7200 CNRS/Université de Strasbourg,
Labex MEDALIS, Faculté de Pharmacie, 74 route du Rhin, 67412 Illkirch, France
| | - Nadia Oueslati
- CNRS UMR 5203, and INSERM U661, and Université Montpellier I et II, Institut de Génomique Fonctionnelle, Département de Pharmacologie Moléculaire, 141 rue de la Cardonille, 34094 Montpellier Cedex 5, France
| | - Abderazak Belhocine
- CNRS UMR 5203, and INSERM U661, and Université Montpellier I et II, Institut de Génomique Fonctionnelle, Département de Pharmacologie Moléculaire, 141 rue de la Cardonille, 34094 Montpellier Cedex 5, France
| | - Elodie Dupuis
- Cisbio Bioassays,
Parc Marcel Boiteux, BP84175, 30200 Codolet, France
| | - Cécile Thomas
- Laboratoire d’Innovation
Thérapeutique, UMR7200 CNRS/Université de Strasbourg,
Labex MEDALIS, Faculté de Pharmacie, 74 route du Rhin, 67412 Illkirch, France
| | - André Mann
- Laboratoire d’Innovation
Thérapeutique, UMR7200 CNRS/Université de Strasbourg,
Labex MEDALIS, Faculté de Pharmacie, 74 route du Rhin, 67412 Illkirch, France
| | - Brigitte Ilien
- Unité Biotechnologie
et Signalisation Cellulaire, UMR 7242 CNRS/Université de Strasbourg,
Labex MEDALIS, Ecole Supérieure de Biotechnologie de Strasbourg, 300 Bvd S. Brant, 67412 Illkirch, France
| | - Didier Rognan
- Laboratoire d’Innovation
Thérapeutique, UMR7200 CNRS/Université de Strasbourg,
Labex MEDALIS, Faculté de Pharmacie, 74 route du Rhin, 67412 Illkirch, France
| | - Eric Trinquet
- Cisbio Bioassays,
Parc Marcel Boiteux, BP84175, 30200 Codolet, France
| | - Marcel Hibert
- Laboratoire d’Innovation
Thérapeutique, UMR7200 CNRS/Université de Strasbourg,
Labex MEDALIS, Faculté de Pharmacie, 74 route du Rhin, 67412 Illkirch, France
| | - Jean-Philippe Pin
- CNRS UMR 5203, and INSERM U661, and Université Montpellier I et II, Institut de Génomique Fonctionnelle, Département de Pharmacologie Moléculaire, 141 rue de la Cardonille, 34094 Montpellier Cedex 5, France
| | - Dominique Bonnet
- Laboratoire d’Innovation
Thérapeutique, UMR7200 CNRS/Université de Strasbourg,
Labex MEDALIS, Faculté de Pharmacie, 74 route du Rhin, 67412 Illkirch, France
| | - Thierry Durroux
- CNRS UMR 5203, and INSERM U661, and Université Montpellier I et II, Institut de Génomique Fonctionnelle, Département de Pharmacologie Moléculaire, 141 rue de la Cardonille, 34094 Montpellier Cedex 5, France
| |
Collapse
|
32
|
A new mechanism of allostery in a G protein-coupled receptor dimer. Nat Chem Biol 2014; 10:745-52. [PMID: 25108820 PMCID: PMC4138267 DOI: 10.1038/nchembio.1593] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 06/26/2014] [Indexed: 01/11/2023]
Abstract
SB269652 (1) is the first drug-like allosteric modulator of the
dopamine D2 receptor (D2R), but contains structural features
associated with orthosteric D2R antagonists. Using a functional complementation
system to control the identity of individual protomers within a dimeric D2R
complex, we converted the pharmacology of the interaction between SB269652 and dopamine
from allosteric to competitive by impairing ligand binding to one of the protomers,
indicating that the allostery requires D2R dimers. Additional experiments
identified a “bitopic” pose for SB269652 extending from the orthosteric
site into a secondary pocket at the extracellular end of the transmembrane (TM) domain,
involving TM2 and TM7. Engagement of this secondary pocket was a requirement for the
allosteric pharmacology of SB269652. This suggests a novel mechanism whereby a bitopic
ligand binds in an extended pose on one G protein-coupled receptor protomer to
allosterically modulate the binding of a ligand to the orthosteric site of a second
protomer.
Collapse
|
33
|
Synthesis and binding profile of haloperidol-based bivalent ligands targeting dopamine D(2)-like receptors. Bioorg Med Chem Lett 2014; 24:3753-6. [PMID: 25047579 DOI: 10.1016/j.bmcl.2014.06.079] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 06/24/2014] [Accepted: 06/26/2014] [Indexed: 01/06/2023]
Abstract
Homodimers of dopamine D2-like receptors are suggested to be of particular importance in the pathophysiology of schizophrenia and, thus, serve as promising targets for the discovery of atypical antipsychotics. This study describes the development of a series of novel bivalent molecules with a pharmacophore derived from the dopamine receptor antagonist haloperidol. These dimers were investigated in comparison to their monomeric analogues for their D2long, D2short, D3, and D4 receptor binding and the ability to bridge two neighboring receptor protomers. Radioligand binding studies provided diagnostic insights when Hill slopes close to two for the bivalent ligand 13 incorporating 22 spacer atoms and a comparative analysis with monovalent control ligands indicated a bivalent binding mode with a simultaneous occupancy of two neighboring binding sites.
Collapse
|
34
|
Cortés A, Gracia E, Moreno E, Mallol J, Lluís C, Canela EI, Casadó V. Moonlighting Adenosine Deaminase: A Target Protein for Drug Development. Med Res Rev 2014; 35:85-125. [DOI: 10.1002/med.21324] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Antoni Cortés
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED); Institute of Biomedicine of the University of Barcelona (IBUB); Department of Biochemistry and Molecular Biology; Faculty of Biology; University of Barcelona; Barcelona Spain
| | - Eduard Gracia
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED); Institute of Biomedicine of the University of Barcelona (IBUB); Department of Biochemistry and Molecular Biology; Faculty of Biology; University of Barcelona; Barcelona Spain
| | - Estefania Moreno
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED); Institute of Biomedicine of the University of Barcelona (IBUB); Department of Biochemistry and Molecular Biology; Faculty of Biology; University of Barcelona; Barcelona Spain
| | - Josefa Mallol
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED); Institute of Biomedicine of the University of Barcelona (IBUB); Department of Biochemistry and Molecular Biology; Faculty of Biology; University of Barcelona; Barcelona Spain
| | - Carme Lluís
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED); Institute of Biomedicine of the University of Barcelona (IBUB); Department of Biochemistry and Molecular Biology; Faculty of Biology; University of Barcelona; Barcelona Spain
| | - Enric I. Canela
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED); Institute of Biomedicine of the University of Barcelona (IBUB); Department of Biochemistry and Molecular Biology; Faculty of Biology; University of Barcelona; Barcelona Spain
| | - Vicent Casadó
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED); Institute of Biomedicine of the University of Barcelona (IBUB); Department of Biochemistry and Molecular Biology; Faculty of Biology; University of Barcelona; Barcelona Spain
| |
Collapse
|
35
|
Asraf H, Salomon S, Nevo A, Sekler I, Mayer D, Hershfinkel M. The ZnR/GPR39 Interacts With the CaSR to Enhance Signaling in Prostate and Salivary Epithelia. J Cell Physiol 2014; 229:868-77. [DOI: 10.1002/jcp.24514] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 11/18/2013] [Indexed: 12/31/2022]
Affiliation(s)
- Hila Asraf
- Department of Physiology and Cell Biology, Faculty of Health Sciences; Ben-Gurion University of the Negev; Beer-Sheva Israel
| | - Shimrit Salomon
- Department of Physiology and Cell Biology, Faculty of Health Sciences; Ben-Gurion University of the Negev; Beer-Sheva Israel
| | - Andrey Nevo
- Department of Physiology and Cell Biology, Faculty of Health Sciences; Ben-Gurion University of the Negev; Beer-Sheva Israel
| | - Israel Sekler
- Department of Physiology and Cell Biology, Faculty of Health Sciences; Ben-Gurion University of the Negev; Beer-Sheva Israel
| | - Doris Mayer
- Hormones and Signal Transduction Group; German Cancer Research Center (DKFZ); Heidelberg Germany
| | - Michal Hershfinkel
- Department of Physiology and Cell Biology, Faculty of Health Sciences; Ben-Gurion University of the Negev; Beer-Sheva Israel
| |
Collapse
|
36
|
Ferré S, Casadó V, Devi LA, Filizola M, Jockers R, Lohse MJ, Milligan G, Pin JP, Guitart X. G protein-coupled receptor oligomerization revisited: functional and pharmacological perspectives. Pharmacol Rev 2014; 66:413-34. [PMID: 24515647 DOI: 10.1124/pr.113.008052] [Citation(s) in RCA: 427] [Impact Index Per Article: 42.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Most evidence indicates that, as for family C G protein-coupled receptors (GPCRs), family A GPCRs form homo- and heteromers. Homodimers seem to be a predominant species, with potential dynamic formation of higher-order oligomers, particularly tetramers. Although monomeric GPCRs can activate G proteins, the pentameric structure constituted by one GPCR homodimer and one heterotrimeric G protein may provide a main functional unit, and oligomeric entities can be viewed as multiples of dimers. It still needs to be resolved if GPCR heteromers are preferentially heterodimers or if they are mostly constituted by heteromers of homodimers. Allosteric mechanisms determine a multiplicity of possible unique pharmacological properties of GPCR homomers and heteromers. Some general mechanisms seem to apply, particularly at the level of ligand-binding properties. In the frame of the dimer-cooperativity model, the two-state dimer model provides the most practical method to analyze ligand-GPCR interactions when considering receptor homomers. In addition to ligand-binding properties, unique properties for each GPCR oligomer emerge in relation to different intrinsic efficacy of ligands for different signaling pathways (functional selectivity). This gives a rationale for the use of GPCR oligomers, and particularly heteromers, as novel targets for drug development. Herein, we review the functional and pharmacological properties of GPCR oligomers and provide some guidelines for the application of discrete direct screening and high-throughput screening approaches to the discovery of receptor-heteromer selective compounds.
Collapse
Affiliation(s)
- Sergi Ferré
- Integrative Neurobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes on Drug Abuse, Department of Health and Human Services, 333 Cassell Drive, Baltimore, Maryland 21224.
| | | | | | | | | | | | | | | | | |
Collapse
|
37
|
Roche D, Gil D, Giraldo J. Mathematical modeling of G protein-coupled receptor function: what can we learn from empirical and mechanistic models? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 796:159-81. [PMID: 24158805 DOI: 10.1007/978-94-007-7423-0_8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Empirical and mechanistic models differ in their approaches to the analysis of pharmacological effect. Whereas the parameters of the former are not physical constants those of the latter embody the nature, often complex, of biology. Empirical models are exclusively used for curve fitting, merely to characterize the shape of the E/[A] curves. Mechanistic models, on the contrary, enable the examination of mechanistic hypotheses by parameter simulation. Regretfully, the many parameters that mechanistic models may include can represent a great difficulty for curve fitting, representing, thus, a challenge for computational method development. In the present study some empirical and mechanistic models are shown and the connections, which may appear in a number of cases between them, are analyzed from the curves they yield. It may be concluded that systematic and careful curve shape analysis can be extremely useful for the understanding of receptor function, ligand classification and drug discovery, thus providing a common language for the communication between pharmacologists and medicinal chemists.
Collapse
Affiliation(s)
- David Roche
- Laboratory of Systems Pharmacology and Bioinformatics, Institut de Neurociències and Unitat de Bioestadística, Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain
| | | | | |
Collapse
|
38
|
Kumari N, Mishra CB, Prakash A, Kumar N, Mongre R, Luthra PM. 8-(Furan-2-yl)-3-phenethylthiazolo[5,4-e][1,2,4]triazolo[1,5-c]pyrimidine-2(3H)-thione as novel, selective and potent adenosine A(2A) receptor antagonist. Neurosci Lett 2013; 558:203-7. [PMID: 24161891 DOI: 10.1016/j.neulet.2013.10.035] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 10/10/2013] [Accepted: 10/13/2013] [Indexed: 11/28/2022]
Abstract
Antagonism of the human A2A receptor has been implicated to alleviate the symptoms associated with Parkinson's disease. The present finding reveals the potential of PTTP (8-(furan-2-yl)-3-phenethylthiazolo[1,2,4]triazolo[1,5-c]pyrimidine-2(3H)-thione) as novel and potent A2AR antagonist. In radioligand binding assay, PTTP showed significantly high binding affinity (Ki 6.3 nM) and selectivity with A2AR (A1R/A2AR=4603) which was comparable to the results of docking analysis (Ki=1.6 nM, ΔG=-14.52 Kcal/mol). PTTP antagonized (0.46 pmol/ml) the effect of NECA-induced increase in cAMP concentration (0.65 pmol/ml) better than SCH58261 (0.55 pmol/ml) in HEK293T cells. Haloperidol and NECA-induced mice pre-treated with PTTP at 10mg/kg showed attenuation in catalepsy and akinesia without significant neurotoxicity in rotarod test at 20mg/kg. Essentially, novel compound demonstrated remarkable potential as A2AR antagonist in the therapy of PD.
Collapse
Affiliation(s)
- Namrata Kumari
- Neuropharmaceutical Chemistry Laboratory, Dr. B.R. Ambedkar Center for Biomedical Research, University of Delhi, North Campus, Mall Road, Delhi 110007, India
| | - Chandra Bhushan Mishra
- Neuropharmaceutical Chemistry Laboratory, Dr. B.R. Ambedkar Center for Biomedical Research, University of Delhi, North Campus, Mall Road, Delhi 110007, India
| | - Amresh Prakash
- Neuropharmaceutical Chemistry Laboratory, Dr. B.R. Ambedkar Center for Biomedical Research, University of Delhi, North Campus, Mall Road, Delhi 110007, India
| | - Nitin Kumar
- Neuropharmaceutical Chemistry Laboratory, Dr. B.R. Ambedkar Center for Biomedical Research, University of Delhi, North Campus, Mall Road, Delhi 110007, India
| | - Rajkumar Mongre
- Neuropharmaceutical Chemistry Laboratory, Dr. B.R. Ambedkar Center for Biomedical Research, University of Delhi, North Campus, Mall Road, Delhi 110007, India
| | - Pratibha Mehta Luthra
- Neuropharmaceutical Chemistry Laboratory, Dr. B.R. Ambedkar Center for Biomedical Research, University of Delhi, North Campus, Mall Road, Delhi 110007, India.
| |
Collapse
|
39
|
Redka DS, Heerklotz H, Wells JW. Efficacy as an Intrinsic Property of the M2 Muscarinic Receptor in Its Tetrameric State. Biochemistry 2013; 52:7405-27. [DOI: 10.1021/bi4003869] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Dar’ya S. Redka
- Department of Pharmaceutical
Sciences,
Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada M5S 3M2
| | - Heiko Heerklotz
- Department of Pharmaceutical
Sciences,
Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada M5S 3M2
| | - James W. Wells
- Department of Pharmaceutical
Sciences,
Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada M5S 3M2
| |
Collapse
|
40
|
Banghart MR, Williams JT, Shah RC, Lavis LD, Sabatini BL. Caged naloxone reveals opioid signaling deactivation kinetics. Mol Pharmacol 2013; 84:687-95. [PMID: 23960100 DOI: 10.1124/mol.113.088096] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The spatiotemporal dynamics of opioid signaling in the brain remain poorly defined. Photoactivatable opioid ligands provide a means to quantitatively measure these dynamics and their underlying mechanisms in brain tissue. Although activation kinetics can be assessed using caged agonists, deactivation kinetics are obscured by slow clearance of agonist in tissue. To reveal deactivation kinetics of opioid signaling we developed a caged competitive antagonist that can be quickly photoreleased in sufficient concentrations to render agonist dissociation effectively irreversible. Carboxynitroveratryl-naloxone (CNV-NLX), a caged analog of the competitive opioid antagonist NLX, was readily synthesized from commercially available NLX in good yield and found to be devoid of antagonist activity at heterologously expressed opioid receptors. Photolysis in slices of rat locus coeruleus produced a rapid inhibition of the ionic currents evoked by multiple agonists of the μ-opioid receptor (MOR), but not of α-adrenergic receptors, which activate the same pool of ion channels. Using the high-affinity peptide agonist dermorphin, we established conditions under which light-driven deactivation rates are independent of agonist concentration and thus intrinsic to the agonist-receptor complex. Under these conditions, some MOR agonists yielded deactivation rates that are limited by G protein signaling, whereas others appeared limited by agonist dissociation. Therefore, the choice of agonist determines which feature of receptor signaling is unmasked by CNV-NLX photolysis.
Collapse
Affiliation(s)
- Matthew R Banghart
- Howard Hughes Medical Institute, Department of Neurobiology, Harvard Medical School, Boston, Massachusetts (M.R.B., R.C.S., B.L.S.); Vollum Institute, Oregon Health & Science University, Portland, Oregon (J.T.W.); and Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia (L.D.L.)
| | | | | | | | | |
Collapse
|
41
|
Fluorescent ligands to investigate GPCR binding properties and oligomerization. Biochem Soc Trans 2013; 41:148-53. [PMID: 23356275 DOI: 10.1042/bst20120237] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Fluorescent ligands for GPCRs (G-protein-coupled receptors) have been synthesized for a long time but their use was usually restricted to receptor localization in the cell by fluorescent imaging microscopy. During the last two decades, the emergence of new fluorescence-based strategies and the concomitant development of fluorescent measurement apparatus have dramatically widened the use of fluorescent ligands. Among the various strategies, TR (time-resolved)-FRET (fluorescence resonance energy transfer) approaches exhibit an interesting potential to study GPCR interactions with various partners. We have derived various sets of ligands that target different GPCRs with fluorophores, which are compatible with TR-FRET strategies. Fluorescent ligands labelled either with a fluorescent donor (such as europium or terbium cryptate) or with a fluorescent acceptor (such as fluorescein, dy647 or Alexa Fluor® 647), for example, kept high affinities for their cognate receptors. These ligands turn out to be interesting tools to develop FRET-based binding assays. We also used these fluorescent ligands to analyse GPCR oligomerization by measuring FRET between ligands bound to receptor dimers. In contrast with FRET strategies, on the basis of receptor labelling, the ligand-based approach we developed is fully compatible with the study of wild-type receptors and therefore with receptors expressed in native tissues. Therefore, by using fluorescent analogues of oxytocin, we demonstrated the existence of oxytocin receptor dimers in the mammary gland of lactating rats.
Collapse
|
42
|
Hammock EA, Levitt P. Modulation of parvalbumin interneuron number by developmentally transient neocortical vasopressin receptor 1a (V1aR). Neuroscience 2012; 222:20-8. [PMID: 22820266 PMCID: PMC3444161 DOI: 10.1016/j.neuroscience.2012.07.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 07/09/2012] [Accepted: 07/11/2012] [Indexed: 11/30/2022]
Abstract
Arginine-vasopressin (AVP) and the vasopressin 1a receptor (V1aR) modulate social behavior and learning and memory in adult animals. Both functions depend upon the normal emergence of the balance of excitation and inhibition (E/I balance) in the neocortex. Here, we tested the hypothesis that V1aR signaling and E/I balance converge through the influence of the neuropeptide on interneuron number achieved in the neocortex. Postnatal mapping of forebrain V1aR binding in male and female mice revealed a transient expression of high levels of receptor in the neocortex and hippocampus in the second and third post-natal weeks. Receptor binding levels in these cortical structures fell dramatically in the adult, maintaining high levels of expression subcortically. Surprisingly, we observed sex differences in the number of calbindin interneurons, and a contribution of V1aR to the number of parvalbumin-immunoreactive neurons in the adult mouse neocortex. These data suggest that individual differences in developmentally transient V1aR signaling and even sex may alter the development of E/I balance in the neocortex, with long-lasting influence on information processing.
Collapse
Affiliation(s)
- Elizabeth A.D. Hammock
- Department of Pediatrics, Vanderbilt University School of Medicine & Vanderbilt Kennedy Center, Vanderbilt University, Nashville TN, 37232
| | - Pat Levitt
- Zilkha Neurogenetic Institute, Department of Cell and Neurobiology, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90089
| |
Collapse
|
43
|
Koshimizu TA, Nakamura K, Egashira N, Hiroyama M, Nonoguchi H, Tanoue A. Vasopressin V1a and V1b Receptors: From Molecules to Physiological Systems. Physiol Rev 2012; 92:1813-64. [DOI: 10.1152/physrev.00035.2011] [Citation(s) in RCA: 250] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The neurohypophysial hormone arginine vasopressin (AVP) is essential for a wide range of physiological functions, including water reabsorption, cardiovascular homeostasis, hormone secretion, and social behavior. These and other actions of AVP are mediated by at least three distinct receptor subtypes: V1a, V1b, and V2. Although the antidiuretic action of AVP and V2 receptor in renal distal tubules and collecting ducts is relatively well understood, recent years have seen an increasing understanding of the physiological roles of V1a and V1b receptors. The V1a receptor is originally found in the vascular smooth muscle and the V1b receptor in the anterior pituitary. Deletion of V1a or V1b receptor genes in mice revealed that the contributions of these receptors extend far beyond cardiovascular or hormone-secreting functions. Together with extensively developed pharmacological tools, genetically altered rodent models have advanced the understanding of a variety of AVP systems. Our report reviews the findings in this important field by covering a wide range of research, from the molecular physiology of V1a and V1b receptors to studies on whole animals, including gene knockout/knockdown studies.
Collapse
Affiliation(s)
- Taka-aki Koshimizu
- Department of Pharmacology, Division of Molecular Pharmacology, Jichi Medical University, Tochigi, Japan; Department of Pharmacology, National Research Institute for Child Health and Development, Tokyo, Japan; Department of Pharmacy, Kyushu University Hospital, Fukuoka, Japan; and Department of Internal Medicine, Kitasato University, Kitasato Institute Medical Center Hospital, Saitama, Japan
| | - Kazuaki Nakamura
- Department of Pharmacology, Division of Molecular Pharmacology, Jichi Medical University, Tochigi, Japan; Department of Pharmacology, National Research Institute for Child Health and Development, Tokyo, Japan; Department of Pharmacy, Kyushu University Hospital, Fukuoka, Japan; and Department of Internal Medicine, Kitasato University, Kitasato Institute Medical Center Hospital, Saitama, Japan
| | - Nobuaki Egashira
- Department of Pharmacology, Division of Molecular Pharmacology, Jichi Medical University, Tochigi, Japan; Department of Pharmacology, National Research Institute for Child Health and Development, Tokyo, Japan; Department of Pharmacy, Kyushu University Hospital, Fukuoka, Japan; and Department of Internal Medicine, Kitasato University, Kitasato Institute Medical Center Hospital, Saitama, Japan
| | - Masami Hiroyama
- Department of Pharmacology, Division of Molecular Pharmacology, Jichi Medical University, Tochigi, Japan; Department of Pharmacology, National Research Institute for Child Health and Development, Tokyo, Japan; Department of Pharmacy, Kyushu University Hospital, Fukuoka, Japan; and Department of Internal Medicine, Kitasato University, Kitasato Institute Medical Center Hospital, Saitama, Japan
| | - Hiroshi Nonoguchi
- Department of Pharmacology, Division of Molecular Pharmacology, Jichi Medical University, Tochigi, Japan; Department of Pharmacology, National Research Institute for Child Health and Development, Tokyo, Japan; Department of Pharmacy, Kyushu University Hospital, Fukuoka, Japan; and Department of Internal Medicine, Kitasato University, Kitasato Institute Medical Center Hospital, Saitama, Japan
| | - Akito Tanoue
- Department of Pharmacology, Division of Molecular Pharmacology, Jichi Medical University, Tochigi, Japan; Department of Pharmacology, National Research Institute for Child Health and Development, Tokyo, Japan; Department of Pharmacy, Kyushu University Hospital, Fukuoka, Japan; and Department of Internal Medicine, Kitasato University, Kitasato Institute Medical Center Hospital, Saitama, Japan
| |
Collapse
|
44
|
Vauquelin G, Van Liefde I. Radioligand dissociation measurements: potential interference of rebinding and allosteric mechanisms and physiological relevance of the biological model systems. Expert Opin Drug Discov 2012; 7:583-95. [DOI: 10.1517/17460441.2012.687720] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
|
45
|
Goddard AD, Watts A. Contributions of fluorescence techniques to understanding G protein-coupled receptor dimerisation. Biophys Rev 2012; 4:291-298. [PMID: 28510206 DOI: 10.1007/s12551-012-0073-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 03/13/2012] [Indexed: 12/27/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are the largest class of eukaryotic cell-surface receptors and, over the last decade, it has become clear that they are capable of dimerisation. Whilst many biochemical and biophysical approaches have been used to study dimerisation, fluorescence techniques, including Förster resonance energy transfer and single molecule fluorescence, have been key players. Here we review recent contributions of fluorescence techniques to investigate GPCR dimers, including dimerisation in cell membranes and native tissues, the effect of ligand binding on dimerisation and the kinetics of dimer formation and dissociation. The challenges of studying multicomponent membrane protein systems have led to the development and refinement of many fluorescence assays, allowing the functional consequences of receptor dimerisation to be investigated and individual protein molecules to be imaged in the membranes of living cells. It is likely that the fluorescence techniques described here will be of use for investigating many other multicomponent membrane protein systems.
Collapse
Affiliation(s)
- Alan D Goddard
- Biomembrane Structure Unit, Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Anthony Watts
- Biomembrane Structure Unit, Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.
| |
Collapse
|
46
|
Manning M, Misicka A, Olma A, Bankowski K, Stoev S, Chini B, Durroux T, Mouillac B, Corbani M, Guillon G. Oxytocin and vasopressin agonists and antagonists as research tools and potential therapeutics. J Neuroendocrinol 2012; 24:609-28. [PMID: 22375852 PMCID: PMC3490377 DOI: 10.1111/j.1365-2826.2012.02303.x] [Citation(s) in RCA: 308] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 02/17/2012] [Accepted: 02/17/2012] [Indexed: 01/08/2023]
Abstract
We recently reviewed the status of peptide and nonpeptide agonists and antagonists for the V(1a), V(1b) and V(2) receptors for arginine vasopressin (AVP) and the oxytocin receptor for oxytocin (OT). In the present review, we update the status of peptides and nonpeptides as: (i) research tools and (ii) therapeutic agents. We also present our recent findings on the design of fluorescent ligands for V(1b) receptor localisation and for OT receptor dimerisation. We note the exciting discoveries regarding two novel naturally occurring analogues of OT. Recent reports of a selective VP V(1a) agonist and a selective OT agonist point to the continued therapeutic potential of peptides in this field. To date, only two nonpeptides, the V(2) /V(1a) antagonist, conivaptan and the V(2) antagonist tolvaptan have received Food and Drug Administration approval for clinical use. The development of nonpeptide AVP V(1a), V(1b) and V(2) antagonists and OT agonists and antagonists has recently been abandoned by Merck, Sanofi and Pfizer. A promising OT antagonist, Retosiban, developed at Glaxo SmithKline is currently in a Phase II clinical trial for the prevention of premature labour. A number of the nonpeptide ligands that were not successful in clinical trials are proving to be valuable as research tools. Peptide agonists and antagonists continue to be very widely used as research tools in this field. In this regard, we present receptor data on some of the most widely used peptide and nonpeptide ligands, as a guide for their use, especially with regard to receptor selectivity and species differences.
Collapse
Affiliation(s)
- M Manning
- Biochemistry and Cancer Biology, University of Toledo College of Medicine, Toledo, OH 43614-2598, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Murat B, Devost D, Andrés M, Mion J, Boulay V, Corbani M, Zingg HH, Guillon G. V1b and CRHR1 receptor heterodimerization mediates synergistic biological actions of vasopressin and CRH. Mol Endocrinol 2012; 26:502-20. [PMID: 22301784 DOI: 10.1210/me.2011-1202] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Vasopressin (AVP) and CRH synergistically regulate adrenocorticotropin and insulin release at the level of the pituitary and pancreas, respectively. Here, we first extended these AVP and CRH coregulation processes to the adrenal medulla. We demonstrate that costimulation of chromaffin cells by AVP and CRH simultaneously induces a catecholamine secretion exceeding the one induced by each hormone alone, thus demonstrating a net potentiation. To further elucidate the molecular mechanisms underlying this synergism, we coexpressed human V1b and CRH receptor (CRHR)1 receptor in HEK293 cells. In this heterologous system, AVP also potentiated CRH-stimulated cAMP accumulation in a dose-dependent and saturable manner. This effect was only partially mimicked by phorbol ester or inhibited by a phospholipase C inhibitor respectively. This finding suggests the existence of an new molecular mechanism, independent from second messenger cross talk. Similarly, CRH potentiated the AVP-induced inositol phosphates production. Using bioluminescence resonance energy transfer, coimmunoprecipitation, and receptor rescue experiments, we demonstrate that V1b and CRHR1 receptors assemble as heterodimers. Moreover, new pharmacological properties emerged upon receptors cotransfection. Taken together, these data strongly suggest that direct molecular interactions between V1b and CRHR1 receptors play an important role in mediating the synergistic interactions between these two receptors.
Collapse
Affiliation(s)
- Brigitte Murat
- Institut de Génomique Fonctionnelle, 141 Rue de la Cardonille, Montpellier Cedex 05, France
| | | | | | | | | | | | | | | |
Collapse
|
48
|
Cottet M, Faklaris O, Maurel D, Scholler P, Doumazane E, Trinquet E, Pin JP, Durroux T. BRET and Time-resolved FRET strategy to study GPCR oligomerization: from cell lines toward native tissues. Front Endocrinol (Lausanne) 2012; 3:92. [PMID: 22837753 PMCID: PMC3401989 DOI: 10.3389/fendo.2012.00092] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 07/03/2012] [Indexed: 11/13/2022] Open
Abstract
The concept of oligomerization of G protein-coupled receptor (GPCR) opens new perspectives regarding physiological function regulation. The capacity of one GPCR to modify its binding and coupling properties by interacting with a second one can be at the origin of regulations unsuspected two decades ago. Although the concept is interesting, its validation at a physiological level is challenging and probably explains why receptor oligomerization is still controversial. Demonstrating direct interactions between two proteins is not trivial since few techniques present a spatial resolution allowing this precision. Resonance energy transfer (RET) strategies are actually the most convenient ones. During the last two decades, bioluminescent resonance energy transfer and time-resolved fluorescence resonance energy transfer (TR-FRET) have been widely used since they exhibit high signal-to-noise ratio. Most of the experiments based on GPCR labeling have been performed in cell lines and it has been shown that all GPCRs have the propensity to form homo- or hetero-oligomers. However, whether these data can be extrapolated to GPCRs expressed in native tissues and explain receptor functioning in real life, remains an open question. Native tissues impose different constraints since GPCR sequences cannot be modified. Recently, a fluorescent ligand-based GPCR labeling strategy combined to a TR-FRET approach has been successfully used to prove the existence of GPCR oligomerization in native tissues. Although the RET-based strategies are generally quite simple to implement, precautions have to be taken before concluding to the absence or the existence of specific interactions between receptors. For example, one should exclude the possibility of collision of receptors diffusing throughout the membrane leading to a specific FRET signal. The advantages and the limits of different approaches will be reviewed and the consequent perspectives discussed.
Collapse
Affiliation(s)
- Martin Cottet
- Institut de Génomique Fonctionnelle CNRS, UMR 5203,Montpellier, France
- INSERM, U.661, Montpellier and Université Montpellier 1,2,Montpellier, France
| | - Orestis Faklaris
- Institut de Génomique Fonctionnelle CNRS, UMR 5203,Montpellier, France
- INSERM, U.661, Montpellier and Université Montpellier 1,2,Montpellier, France
| | - Damien Maurel
- Institut de Génomique Fonctionnelle CNRS, UMR 5203,Montpellier, France
- INSERM, U.661, Montpellier and Université Montpellier 1,2,Montpellier, France
| | - Pauline Scholler
- Institut de Génomique Fonctionnelle CNRS, UMR 5203,Montpellier, France
- INSERM, U.661, Montpellier and Université Montpellier 1,2,Montpellier, France
| | - Etienne Doumazane
- Institut de Génomique Fonctionnelle CNRS, UMR 5203,Montpellier, France
- INSERM, U.661, Montpellier and Université Montpellier 1,2,Montpellier, France
| | | | - Jean-Philippe Pin
- Institut de Génomique Fonctionnelle CNRS, UMR 5203,Montpellier, France
- INSERM, U.661, Montpellier and Université Montpellier 1,2,Montpellier, France
| | - Thierry Durroux
- Institut de Génomique Fonctionnelle CNRS, UMR 5203,Montpellier, France
- INSERM, U.661, Montpellier and Université Montpellier 1,2,Montpellier, France
- *Correspondence: Thierry Durroux, Institut de Génomique Fonctionnelle CNRS, UMR 5203, Montpellier, France; INSERM U661, Montpellier and Université Montpellier 1,2, 141 Rue de la Cardonille, 34094 Montpellier Cedex 5, France. e-mail:
| |
Collapse
|
49
|
Ng SYL, Lee LTO, Chow BKC. Receptor oligomerization: from early evidence to current understanding in class B GPCRs. Front Endocrinol (Lausanne) 2012; 3:175. [PMID: 23316183 PMCID: PMC3539651 DOI: 10.3389/fendo.2012.00175] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 12/11/2012] [Indexed: 01/06/2023] Open
Abstract
Dimerization or oligomerization of G protein-coupled receptors (GPCRs) are known to modulate receptor functions in terms of ontogeny, ligand-oriented regulation, pharmacological diversity, signal transduction, and internalization. Class B GPCRs are receptors to a family of hormones including secretin, growth hormone-releasing hormone, vasoactive intestinal polypeptide and parathyroid hormone, among others. The functional implications of receptor dimerization have extensively been studied in class A GPCRs, while less is known regarding its function in class B GPCRs. This article reviews receptor oligomerization in terms of the early evidence and current understanding particularly of class B GPCRs.
Collapse
Affiliation(s)
| | | | - Billy K. C. Chow
- *Correspondence: Billy K. C. Chow, Endocrinology, School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China. e-mail:
| |
Collapse
|
50
|
Vischer HF, Watts AO, Nijmeijer S, Leurs R. G protein-coupled receptors: walking hand-in-hand, talking hand-in-hand? Br J Pharmacol 2011; 163:246-60. [PMID: 21244374 DOI: 10.1111/j.1476-5381.2011.01229.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Most cells express a panel of different G protein-coupled receptors (GPCRs) allowing them to respond to at least a corresponding variety of extracellular ligands. In order to come to an integrative well-balanced functional response these ligand-receptor pairs can often cross-regulate each other. Although most GPCRs are fully capable to induce intracellular signalling upon agonist binding on their own, many GPCRs, if not all, appear to exist and function in homomeric and/or heteromeric assemblies for at least some time. Such heteromeric organization offers unique allosteric control of receptor pharmacology and function between the protomers and might even unmask 'new' features. However, it is important to realize that some functional consequences that are proposed to originate from heteromeric receptor interactions may also be observed due to intracellular crosstalk between signalling pathways of non-associated GPCRs.
Collapse
Affiliation(s)
- Henry F Vischer
- Leiden/Amsterdam Center for Drug Research (LACDR), Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, Amsterdam, The Netherlands
| | | | | | | |
Collapse
|