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Giorgioni G, Bonifazi A, Matucci R, Matteucci F, Piergentili A, Piergentili A, Quaglia W, Gervasoni S, Vistoli G, Vittorio S, Del Bello F. New potent muscarinic receptor ligands bearing the 1,4-dioxane nucleus: Investigation on the nature of the substituent in position 2. Arch Pharm (Weinheim) 2024; 357:e2400337. [PMID: 39054609 DOI: 10.1002/ardp.202400337] [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: 05/02/2024] [Revised: 07/04/2024] [Accepted: 07/05/2024] [Indexed: 07/27/2024]
Abstract
A new series of muscarinic acetylcholine receptor (mAChR) ligands obtained by inserting different substituents in position 2 of the potent 6,6-diphenyl-1,4-dioxane antagonists 4 and 5 was designed and synthesized to investigate the influence of steric bulk on the mAChR affinity. Specifically, the insertion of a 2-methyl group, affording compounds 6 and 9, resulted as the most favorable modification in terms of affinity for all muscarinic subtypes. As supported by computational studies performed on the hM1 receptor, this substituent may contribute to stabilize the ligand within the binding site by favoring the formation of stable interactions between the cationic head of the ligand and the residue D105. The increase of steric bulk, obtained by replacing the methyl group with an ethyl (7 and 10) and especially a phenyl substituent (8 and 11), caused a marked decrease of mAChR affinity, demonstrating the crucial role played by the steric bulk of the 2-substituent in the mAChR interaction. The most intriguing result was obtained with the tertiary amine 9, which, surprisingly, showed two different pKi values for all mAChRs, with preferential subpicomolar affinities for the M1, M3, and M4 subtypes. Interestingly, biphasic curves were also observed with both the eutomer (S)-(-)-9 and the distomer (R)-( + )-9.
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Affiliation(s)
- Gianfabio Giorgioni
- Scuola di Scienze del Farmaco e dei Prodotti della Salute, Università degli Studi di Camerino, Camerino, Italy
| | - Alessandro Bonifazi
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse-Intramural Research Program, National Institutes of Health, Baltimore, USA
| | - Rosanna Matucci
- Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino (NEUROFARBA), Sezione di Farmacologia e Tossicologia, Università degli Studi di Firenze, Firenze, Italy
| | - Federica Matteucci
- Scuola di Scienze del Farmaco e dei Prodotti della Salute, Università degli Studi di Camerino, Camerino, Italy
| | - Alessandro Piergentili
- Scuola di Scienze del Farmaco e dei Prodotti della Salute, Università degli Studi di Camerino, Camerino, Italy
| | - Alessia Piergentili
- Scuola di Scienze del Farmaco e dei Prodotti della Salute, Università degli Studi di Camerino, Camerino, Italy
| | - Wilma Quaglia
- Scuola di Scienze del Farmaco e dei Prodotti della Salute, Università degli Studi di Camerino, Camerino, Italy
| | - Silvia Gervasoni
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Milano, Italy
- Dipartimento di Fisica, Università di Cagliari, Cittadella Universitaria di Monserrato, Monserrato, Italy
| | - Giulio Vistoli
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Milano, Italy
| | - Serena Vittorio
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Milano, Italy
| | - Fabio Del Bello
- Scuola di Scienze del Farmaco e dei Prodotti della Salute, Università degli Studi di Camerino, Camerino, Italy
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Paul SM, Yohn SE, Popiolek M, Miller AC, Felder CC. Muscarinic Acetylcholine Receptor Agonists as Novel Treatments for Schizophrenia. Am J Psychiatry 2022; 179:611-627. [PMID: 35758639 DOI: 10.1176/appi.ajp.21101083] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Schizophrenia remains a challenging disease to treat effectively with current antipsychotic medications due to their limited efficacy across the entire spectrum of core symptoms as well as their often burdensome side-effect profiles and poor tolerability. An unmet need remains for novel, mechanistically unique, and better tolerated therapeutic agents for treating schizophrenia, especially those that treat not only positive symptoms but also the negative and cognitive symptoms of the disease. Almost 25 years ago, the muscarinic acetylcholine receptor (mAChR) agonist xanomeline was reported to reduce psychotic symptoms and improve cognition in patients with Alzheimer's disease. The antipsychotic and procognitive properties of xanomeline were subsequently confirmed in a small study of acutely psychotic patients with chronic schizophrenia. These unexpected clinical findings have prompted considerable efforts across academia and industry to target mAChRs as a new approach to potentially treat schizophrenia and other psychotic disorders. The authors discuss recent advances in mAChR biology and pharmacology and the current understanding of the relative roles of the various mAChR subtypes, their downstream cellular effectors, and key neural circuits mediating the reduction in the core symptoms of schizophrenia in patients treated with xanomeline. They also provide an update on the status of novel mAChR agonists currently in development for potential treatment of schizophrenia and other neuropsychiatric disorders.
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Balanced modulation of neuromuscular synaptic transmission via M1 and M2 muscarinic receptors during inhibition of cholinesterases. Sci Rep 2022; 12:1688. [PMID: 35105922 PMCID: PMC8807813 DOI: 10.1038/s41598-022-05730-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 01/17/2022] [Indexed: 11/16/2022] Open
Abstract
Organophosphorus (OP) compounds that inhibit acetylcholinesterase are a common cause of poisoning worldwide, resulting in several hundred thousand deaths each year. The pathways activated during OP compound poisoning via overstimulation of muscarinic acetylcholine receptors (mAChRs) play a decisive role in toxidrome. The antidotal therapy includes atropine, which is a nonspecific blocker of all mAChR subtypes. Atropine is efficient for mitigating depression in respiratory control centers but does not benefit patients with OP-induced skeletal muscle weakness. By using an ex vivo model of OP-induced muscle weakness, we studied the effects of the M1/M4 mAChR antagonist pirenzepine and the M2/M4 mAChR antagonist methoctramine on the force of mouse diaphragm muscle contraction. It was shown that weakness caused by the application of paraoxon can be significantly prevented by methoctramine (1 µM). However, neither pirenzepine (0.1 µM) nor atropine (1 µM) was able to prevent muscle weakness. Moreover, the application of pirenzepine significantly reduced the positive effect of methoctramine. Thus, balanced modulation of neuromuscular synaptic transmission via M1 and M2 mAChRs contributes to paraoxon-induced muscle weakness. It was shown that methoctramine (10 µmol/kg, i.p.) and atropine (50 µmol/kg, i.p.) were equieffective toward increasing the survival of mice poisoned with a 2xLD50 dose of paraoxon.
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Johnstone EKM, See HB, Abhayawardana RS, Song A, Rosengren KJ, Hill SJ, Pfleger KDG. Investigation of Receptor Heteromers Using NanoBRET Ligand Binding. Int J Mol Sci 2021; 22:1082. [PMID: 33499147 PMCID: PMC7866079 DOI: 10.3390/ijms22031082] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 01/19/2021] [Accepted: 01/19/2021] [Indexed: 12/20/2022] Open
Abstract
Receptor heteromerization is the formation of a complex involving at least two different receptors with pharmacology that is distinct from that exhibited by its constituent receptor units. Detection of these complexes and monitoring their pharmacology is crucial for understanding how receptors function. The Receptor-Heteromer Investigation Technology (Receptor-HIT) utilizes ligand-dependent modulation of interactions between receptors and specific biomolecules for the detection and profiling of heteromer complexes. Previously, the interacting biomolecules used in Receptor-HIT assays have been intracellular proteins, however in this study we have for the first time used bioluminescence resonance energy transfer (BRET) with fluorescently-labeled ligands to investigate heteromerization of receptors on the cell surface. Using the Receptor-HIT ligand binding assay with NanoBRET, we have successfully investigated heteromers between the angiotensin II type 1 (AT1) receptor and the β2 adrenergic receptor (AT1-β2AR heteromer), as well as between the AT1 and angiotensin II type 2 receptor (AT1-AT2 heteromer).
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Affiliation(s)
- Elizabeth K. M. Johnstone
- Molecular Endocrinology and Pharmacology Group, Harry Perkins Institute of Medical Research, Nedlands, WA 6009, Australia; (H.B.S.); (R.S.A.); (S.J.H.)
- Centre for Medical Research, The University of Western Australia, Crawley, WA 6009, Australia
- Australian Research Council Centre for Personalised Therapeutics Technologies, Canberra, NSW 2609, Australia
| | - Heng B. See
- Molecular Endocrinology and Pharmacology Group, Harry Perkins Institute of Medical Research, Nedlands, WA 6009, Australia; (H.B.S.); (R.S.A.); (S.J.H.)
- Centre for Medical Research, The University of Western Australia, Crawley, WA 6009, Australia
- Australian Research Council Centre for Personalised Therapeutics Technologies, Canberra, NSW 2609, Australia
| | - Rekhati S. Abhayawardana
- Molecular Endocrinology and Pharmacology Group, Harry Perkins Institute of Medical Research, Nedlands, WA 6009, Australia; (H.B.S.); (R.S.A.); (S.J.H.)
- Centre for Medical Research, The University of Western Australia, Crawley, WA 6009, Australia
- Australian Research Council Centre for Personalised Therapeutics Technologies, Canberra, NSW 2609, Australia
| | - Angela Song
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, St Lucia, QLD 4072, Australia; (A.S.); (K.J.R.)
| | - K. Johan Rosengren
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, St Lucia, QLD 4072, Australia; (A.S.); (K.J.R.)
| | - Stephen J. Hill
- Molecular Endocrinology and Pharmacology Group, Harry Perkins Institute of Medical Research, Nedlands, WA 6009, Australia; (H.B.S.); (R.S.A.); (S.J.H.)
- Centre for Medical Research, The University of Western Australia, Crawley, WA 6009, Australia
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham Medical School, Nottingham NG7 2UH, UK
- Centre of Membrane Proteins and Receptors, University of Nottingham, Midlands NG7 2UH, UK
| | - Kevin D. G. Pfleger
- Molecular Endocrinology and Pharmacology Group, Harry Perkins Institute of Medical Research, Nedlands, WA 6009, Australia; (H.B.S.); (R.S.A.); (S.J.H.)
- Centre for Medical Research, The University of Western Australia, Crawley, WA 6009, Australia
- Australian Research Council Centre for Personalised Therapeutics Technologies, Canberra, NSW 2609, Australia
- Dimerix Limited, Nedlands, WA 6009, Australia
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5
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Crans RAJ, Wouters E, Valle-León M, Taura J, Massari CM, Fernández-Dueñas V, Stove CP, Ciruela F. Striatal Dopamine D 2-Muscarinic Acetylcholine M 1 Receptor-Receptor Interaction in a Model of Movement Disorders. Front Pharmacol 2020; 11:194. [PMID: 32231561 PMCID: PMC7083216 DOI: 10.3389/fphar.2020.00194] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 02/11/2020] [Indexed: 12/17/2022] Open
Abstract
Parkinson’s disease (PD) is a neurodegenerative disorder characterized by motor control deficits, which is associated with the loss of striatal dopaminergic neurons from the substantia nigra. In parallel to dopaminergic denervation, there is an increase of acetylcholine within the striatum, resulting in a striatal dopaminergic–cholinergic neurotransmission imbalance. Currently, available PD pharmacotherapy (e.g., prodopaminergic drugs) does not reinstate the altered dopaminergic–cholinergic balance. In addition, it can eventually elicit cholinergic-related adverse effects. Here, we investigated the interplay between dopaminergic and cholinergic systems by assessing the physical and functional interaction of dopamine D2 and muscarinic acetylcholine M1 receptors (D2R and M1R, respectively), both expressed at striatopallidal medium spiny neurons. First, we provided evidence for the existence of D2R–M1R complexes via biochemical (i.e., co-immunoprecipitation) and biophysical (i.e., BRET1 and NanoBiT®) assays, performed in transiently transfected HEK293T cells. Subsequently, a D2R–M1R co-distribution in the mouse striatum was observed through double-immunofluorescence staining and AlphaLISA® immunoassay. Finally, we evaluated the functional interplay between both receptors via behavioral studies, by implementing the classical acute reserpine pharmacological animal model of experimental parkinsonism. Reserpinized mice were administered with a D2R-selective agonist (sumanirole) and/or an M1R-selective antagonist (VU0255035), and alterations in PD-related behavioral tasks (i.e., locomotor activity) were evaluated. Importantly, VU0255035 (10 mg/kg) potentiated the antiparkinsonian-like effects (i.e., increased locomotor activity and decreased catalepsy) of an ineffective sumanirole dose (3 mg/kg). Altogether, our data suggest the existence of putative striatal D2R/M1R heteromers, which might be a relevant target to manage PD motor impairments with fewer adverse effects.
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Affiliation(s)
- René A J Crans
- Laboratory of Toxicology, Department of Bioanalysis, Ghent University, Ghent, Belgium.,Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental, Facultat de Medicina, IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain
| | - Elise Wouters
- Laboratory of Toxicology, Department of Bioanalysis, Ghent University, Ghent, Belgium
| | - Marta Valle-León
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental, Facultat de Medicina, IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain.,Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
| | - Jaume Taura
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental, Facultat de Medicina, IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain.,Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
| | - Caio M Massari
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental, Facultat de Medicina, IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain.,Programa de Poìs-graduação em Bioquiìmica, Centro de Ciencias Bioloìgicas, Universidade Federal de Santa Catarina, Florianoìpolis, Brazil
| | - Víctor Fernández-Dueñas
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental, Facultat de Medicina, IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain.,Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
| | - Christophe P Stove
- Laboratory of Toxicology, Department of Bioanalysis, Ghent University, Ghent, Belgium
| | - Francisco Ciruela
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental, Facultat de Medicina, IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain.,Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
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6
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Beltrame SP, Carrera Páez LC, Auger SR, Sabra AH, Bilder CR, Waldner CI, Goin JC. Impairment of agonist-induced M 2 muscarinic receptor activation by autoantibodies from chagasic patients with cardiovascular dysautonomia. Clin Immunol 2020; 212:108346. [PMID: 31954803 DOI: 10.1016/j.clim.2020.108346] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Revised: 01/13/2020] [Accepted: 01/14/2020] [Indexed: 10/25/2022]
Abstract
Previous studies showed that circulating autoantibodies against M2 muscarinic receptors (anti-M2R Ab) are associated with decreased cardiac parasympathetic modulation in patients with chronic Chagas disease (CD). Here we investigated whether the exposure of M2R to such antibodies could impair agonist-induced receptor activation, leading to the inhibition of associated signaling pathways. Preincubation of M2R-expressing HEK 293T cells with serum IgG fractions from chagasic patients with cardiovascular dysautonomia, followed by the addition of carbachol, resulted in the attenuation of agonist-induced Gi protein activation and arrestin-2 recruitment. These effects were not mimicked by the corresponding Fab fractions, suggesting that they occur through receptor crosslinking. IgG autoantibodies did not enhance M2R/arrestin interaction or promote M2R internalization, suggesting that their inhibitory effects are not likely a result of short-term receptor regulation. Rather, these immunoglobulins could function as negative allosteric modulators of acetylcholine-mediated responses, thereby contributing to the development of parasympathetic dysfunction in patients with CD.
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Affiliation(s)
- Sabrina P Beltrame
- Laboratorio de Farmacología Molecular, Centro de Estudios Farmacológicos y Botánicos (CEFYBO-CONICET-UBA) and II Cátedra de Farmacología, Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155, Piso 16, C1121ABG Buenos Aires, Argentina.
| | - Laura C Carrera Páez
- Laboratorio de Farmacología Molecular, Centro de Estudios Farmacológicos y Botánicos (CEFYBO-CONICET-UBA) and II Cátedra de Farmacología, Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155, Piso 16, C1121ABG Buenos Aires, Argentina.
| | - Sergio R Auger
- Hospital D.F. Santojanni, Pilar 950, PB, C1408INH Buenos Aires, Argentina.
| | - Ahmad H Sabra
- Hospital D.F. Santojanni, Pilar 950, PB, C1408INH Buenos Aires, Argentina.
| | - Claudio R Bilder
- Laboratorio de Neurogastroenterología, Fundación Favaloro-Hospital Universitario, Av. Belgrano 1746, 1er Piso, C1093AAS Buenos Aires, Argentina.
| | - Claudia I Waldner
- Laboratorio de Inmunidad Celular y Molecular, Centro de Estudios Farmacológicos y Botánicos (CEFYBO-CONICET-UBA), Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155, Piso 16, C1121ABG Buenos Aires, Argentina.
| | - Juan C Goin
- Laboratorio de Farmacología Molecular, Centro de Estudios Farmacológicos y Botánicos (CEFYBO-CONICET-UBA) and II Cátedra de Farmacología, Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155, Piso 16, C1121ABG Buenos Aires, Argentina.
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Neurochemical Organization of the Drosophila Brain Visualized by Endogenously Tagged Neurotransmitter Receptors. Cell Rep 2020; 30:284-297.e5. [DOI: 10.1016/j.celrep.2019.12.018] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Revised: 10/19/2019] [Accepted: 12/06/2019] [Indexed: 02/08/2023] Open
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Single Proteoliposome High-Content Analysis Reveals Differences in the Homo-Oligomerization of GPCRs. Biophys J 2019; 115:300-312. [PMID: 30021106 DOI: 10.1016/j.bpj.2018.05.036] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 05/28/2018] [Accepted: 05/31/2018] [Indexed: 11/23/2022] Open
Abstract
G-protein-coupled receptors (GPCRs) control vital cellular signaling pathways. GPCR oligomerization is proposed to increase signaling diversity. However, many reports have arrived at disparate conclusions regarding the existence, stability, and stoichiometry of GPCR oligomers, partly because of cellular complexity and ensemble averaging of intrareconstitution heterogeneities that complicate the interpretation of oligomerization data. To overcome these limitations, we exploited fluorescence-microscopy-based high-content analysis of single proteoliposomes. This allowed multidimensional quantification of intrinsic monomer-monomer interactions of three class A GPCRs (β2-adrenergic receptor, cannabinoid receptor type 1, and opsin). Using a billion-fold less protein than conventional assays, we quantified oligomer stoichiometries, association constants, and the influence of two ligands and membrane curvature on oligomerization, revealing key similarities and differences for three GPCRs with decidedly different physiological functions. The assays introduced here will assist with the quantitative experimental observation of oligomerization for transmembrane proteins in general.
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Moreno E, Cavic M, Krivokuca A, Casadó V, Canela E. The Endocannabinoid System as a Target in Cancer Diseases: Are We There Yet? Front Pharmacol 2019; 10:339. [PMID: 31024307 PMCID: PMC6459931 DOI: 10.3389/fphar.2019.00339] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 03/19/2019] [Indexed: 12/15/2022] Open
Abstract
The endocannabinoid system (ECS) has been placed in the anti-cancer spotlight in the last decade. The immense data load published on its dual role in both tumorigenesis and inhibition of tumor growth and metastatic spread has transformed the cannabinoid receptors CB1 (CB1R) and CB2 (CB2R), and other members of the endocannabinoid-like system, into attractive new targets for the treatment of various cancer subtypes. Although the clinical use of cannabinoids has been extensively documented in the palliative setting, clinical trials on their application as anti-cancer drugs are still ongoing. As drug repurposing is significantly faster and more economical than de novo introduction of a new drug into the clinic, there is hope that the existing pharmacokinetic and safety data on the ECS ligands will contribute to their successful translation into oncological healthcare. CB1R and CB2R are members of a large family of membrane proteins called G protein-coupled receptors (GPCR). GPCRs can form homodimers, heterodimers and higher order oligomers with other GPCRs or non-GPCRs. Currently, several CB1R and CB2R-containing heteromers have been reported and, in cancer cells, CB2R form heteromers with the G protein-coupled chemokine receptor CXCR4, the G protein-coupled receptor 55 (GPR55) and the tyrosine kinase receptor (TKR) human V-Erb-B2 Avian Erythroblastic Leukemia Viral Oncogene Homolog 2 (HER2). These protein complexes possess unique pharmacological and signaling properties, and their modulation might affect the antitumoral activity of the ECS. This review will explore the potential of the endocannabinoid network in the anti-cancer setting as well as the clinical and ethical pitfalls behind it, and will develop on the value of cannabinoid receptor heteromers as potential new targets for anti-cancer therapies and as prognostic biomarkers.
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Affiliation(s)
- Estefanía Moreno
- Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Institute of Biomedicine (IBUB), University of Barcelona, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Milena Cavic
- Department of Experimental Oncology, Institute for Oncology and Radiology of Serbia, Belgrade, Serbia
| | - Ana Krivokuca
- Department of Experimental Oncology, Institute for Oncology and Radiology of Serbia, Belgrade, Serbia
| | - Vicent Casadó
- Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Institute of Biomedicine (IBUB), University of Barcelona, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Enric Canela
- Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Institute of Biomedicine (IBUB), University of Barcelona, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
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Cortés A, Casadó-Anguera V, Moreno E, Casadó V. The heterotetrameric structure of the adenosine A 1-dopamine D 1 receptor complex: Pharmacological implication for restless legs syndrome. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2019; 84:37-78. [PMID: 31229177 DOI: 10.1016/bs.apha.2019.01.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Dopaminergic and purinergic signaling play a pivotal role in neurological diseases associated with motor symptoms, including Parkinson's disease (PD), multiple sclerosis, amyotrophic lateral sclerosis, Huntington disease, Restless Legs Syndrome (RLS), spinal cord injury (SCI), and ataxias. Extracellular dopamine and adenosine exert their functions interacting with specific dopamine (DR) or adenosine (AR) receptors, respectively, expressed on the surface of target cells. These receptors are members of the family A of G protein-coupled receptors (GPCRs), which is the largest protein superfamily in mammalian genomes. GPCRs are target of about 40% of all current marketed drugs, highlighting their importance in clinical medicine. The striatum receives the densest dopamine innervations and contains the highest density of dopamine receptors. The modulatory role of adenosine on dopaminergic transmission depends largely on the existence of antagonistic interactions mediated by specific subtypes of DRs and ARs, the so-called A2AR-D2R and A1R-D1R interactions. Due to the dopamine/adenosine antagonism in the CNS, it was proposed that ARs and DRs could form heteromers in the neuronal cell surface. Therefore, adenosine can affect dopaminergic signaling through receptor-receptor interactions and by modulations in their shared intracellular pathways in the striatum and spinal cord. In this work we describe the allosteric modulations between GPCR protomers, focusing in those of adenosine and dopamine within the A1R-D1R heteromeric complex, which is involved in RLS. We also propose that the knowledge about the intricate allosteric interactions within the A1R-D1R heterotetramer, may facilitate the treatment of motor alterations, not only when the dopamine pathway is hyperactivated (RLS, chorea, etc.) but also when motor function is decreased (SCI, aging, PD, etc.).
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Affiliation(s)
- Antoni Cortés
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain; Institute of Biomedicine of the University of Barcelona (IBUB), Barcelona, Spain; Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Verònica Casadó-Anguera
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain; Institute of Biomedicine of the University of Barcelona (IBUB), Barcelona, Spain; Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Estefanía Moreno
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain; Institute of Biomedicine of the University of Barcelona (IBUB), Barcelona, Spain; Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Vicent Casadó
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain; Institute of Biomedicine of the University of Barcelona (IBUB), Barcelona, Spain; Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona, Barcelona, Spain.
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11
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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.
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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.
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Marsango S, Ward RJ, Alvarez-Curto E, Milligan G. Muscarinic receptor oligomerization. Neuropharmacology 2018; 136:401-410. [PMID: 29146505 PMCID: PMC6078712 DOI: 10.1016/j.neuropharm.2017.11.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 11/01/2017] [Accepted: 11/13/2017] [Indexed: 12/30/2022]
Abstract
G protein-coupled receptors (GPCRs) have been classically described as monomeric entities that function by binding in a 1:1 stoichiometric ratio to both ligand and downstream signalling proteins. However, in recent years, a growing number of studies has supported the hypothesis that these receptors can interact to form dimers and higher order oligomers although the molecular basis for these interactions, the overall quaternary arrangements and the functional importance of GPCR oligomerization remain topics of intense speculation. Muscarinic acetylcholine receptors belong to class A of the GPCR family. Each muscarinic receptor subtype has its own particular distribution throughout the central and peripheral nervous systems. In the central nervous system, muscarinic receptors regulate several sensory, cognitive, and motor functions while, in the peripheral nervous system, they are involved in the regulation of heart rate, stimulation of glandular secretion and smooth muscle contraction. Muscarinic acetylcholine receptors have long been used as a model for the study of GPCR structure and function and to address aspects of GPCR dimerization using a broad range of approaches. In this review, the prevailing knowledge regarding the quaternary arrangement for the various muscarinic acetylcholine receptors has been summarized by discussing work ranging from initial results obtained using more traditional biochemical approaches to those generated with more modern biophysical techniques. This article is part of the Special Issue entitled 'Neuropharmacology on Muscarinic Receptors'.
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Affiliation(s)
- 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, Scotland, 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, Scotland, UK.
| | - Elisa Alvarez-Curto
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, 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, Scotland, UK
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13
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Wang W, Qiao Y, Li Z. New Insights into Modes of GPCR Activation. Trends Pharmacol Sci 2018; 39:367-386. [DOI: 10.1016/j.tips.2018.01.001] [Citation(s) in RCA: 129] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 01/03/2018] [Accepted: 01/08/2018] [Indexed: 12/22/2022]
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14
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Felce JH, Davis SJ, Klenerman D. Single-Molecule Analysis of G Protein-Coupled Receptor Stoichiometry: Approaches and Limitations. Trends Pharmacol Sci 2018; 39:96-108. [PMID: 29122289 DOI: 10.1016/j.tips.2017.10.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Revised: 10/06/2017] [Accepted: 10/10/2017] [Indexed: 01/17/2023]
Abstract
How G protein-coupled receptors (GPCRs) are organized at the cell surface remains highly contentious. Single-molecule (SM) imaging is starting to inform this debate as receptor behavior can now be visualized directly, without the need for interpreting ensemble data. The limited number of SM studies of GPCRs undertaken to date have strongly suggested that dimerization is at most transient, and that most receptors are monomeric at any given time. However, even SM data has its caveats and needs to be interpreted carefully. Here, we discuss the types of SM imaging strategies used to examine GPCR stoichiometry and consider some of these caveats. We also emphasize that attempts to resolve the debate ought to rely on orthogonal approaches to measuring receptor stoichiometry.
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Affiliation(s)
- James H Felce
- Kennedy Institute of Rheumatology, University of Oxford, Oxford OX3 7FY, UK.
| | - Simon J Davis
- Radcliffe Department of Medicine and Medical Research Council Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - David Klenerman
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK
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Kasai RS, Ito SV, Awane RM, Fujiwara TK, Kusumi A. The Class-A GPCR Dopamine D2 Receptor Forms Transient Dimers Stabilized by Agonists: Detection by Single-Molecule Tracking. Cell Biochem Biophys 2017; 76:29-37. [PMID: 29116599 PMCID: PMC5913388 DOI: 10.1007/s12013-017-0829-y] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 09/18/2017] [Indexed: 01/06/2023]
Abstract
Whether class-A G-protein coupled receptors (GPCRs) exist and work as monomers or dimers has drawn extensive attention. A class-A GPCR dopamine D2 receptor (D2R) is involved in many physiological and pathological processes and diseases, indicating its critical role in proper functioning of neuronal circuits. In particular, D2R homodimers might play key roles in schizophrenia development and amphetamine-induced psychosis. Here, using single-molecule imaging, we directly tracked single D2R molecules in the plasma membrane at a physiological temperature of 37 °C, and unequivocally determined that D2R forms transient dimers with a lifetime of 68 ms in its resting state. Agonist addition prolonged the dimer lifetime by a factor of ~1.5, suggesting the possibility that transient dimers might be involved in signaling.
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Affiliation(s)
- Rinshi S Kasai
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, 606-8507, Japan
| | - Shuichi V Ito
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, 606-8507, Japan
| | - Ryo M Awane
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, 606-8507, Japan
| | - Takahiro K Fujiwara
- Center for Meso-Bio Single-Molecule Imaging (CeMI), Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto, 606-8507, Japan
| | - Akihiro Kusumi
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, 606-8507, Japan. .,Center for Meso-Bio Single-Molecule Imaging (CeMI), Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto, 606-8507, Japan. .,Membrane Cooperativity Unit, Okinawa Institute of Science and Technology, Okinawa, 904-0495, Japan.
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16
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Di Liberto V, Borroto-Escuela DO, Frinchi M, Verdi V, Fuxe K, Belluardo N, Mudò G. Existence of muscarinic acetylcholine receptor (mAChR) and fibroblast growth factor receptor (FGFR) heteroreceptor complexes and their enhancement of neurite outgrowth in neural hippocampal cultures. Biochim Biophys Acta Gen Subj 2016; 1861:235-245. [PMID: 27815219 DOI: 10.1016/j.bbagen.2016.10.026] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 10/15/2016] [Accepted: 10/31/2016] [Indexed: 12/19/2022]
Abstract
BACKGROUND Recently, it was demonstrated that G-protein-coupled receptors (GPCRs) can transactivate tyrosine kinase receptors in absence of their ligands. In this work, driven by the observation that mAChRs and fibroblast growth factor receptors (FGFRs) share signalling pathways and regulation of brain functions, it was decided to explore whether mAChRs activation may transactivate FGFRs and, if so, to characterize the related trophic effects in cultured hippocampal neurons. METHODS Oxotremorine-M transactivation of FGFRs and related trophic effects were tested in primary hippocampal neurons. Western blotting and in situ proximity ligation assay (PLA) were used to detect FGFR phosphorylation (pFGFR) levels and M1R-FGFR1 heteroreceptor complexes, respectively. RESULTS Oxotremorine-M, a non-selective mAChRs agonist, was able to transactivate FGFR and this transactivation was blocked by Src inhibitors. Oxotremorine-M treatment produced a significant increase in the primary neurite outgrowth that was blocked by pre-treatment with the pFGFR inhibitor SU5402 and Src inhibitors. This trophic effect was almost similar to that induced by fibroblast growth factor-2 (FGF-2). By using atropine as nonselective mAChRs or pirenzepine as selective antagonist for M1 receptor (M1R) we could show that mAChRs are involved in modulating the pFGFRs. Using PLA, M1R-FGFR1 heteroreceptor complexes were identified in the hippocampus and cerebral cortex. CONCLUSION The current findings, by showing functional mAChR-FGFR interactions, will contribute to advance the understanding of the mechanisms involved in the actions of cholinergic drugs on neuronal plasticity. GENERAL SIGNIFICANT Data may help to develop novel therapeutic strategies not only for neurodegenerative diseases but also for depression-induced atrophy of hippocampal neurons.
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Affiliation(s)
- V Di Liberto
- Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Corso Tukory 129, 90134 Palermo, Italy.
| | - D O Borroto-Escuela
- Karolinska Instituet, Department of Neuroscience, Retzius väg 8, 17177 Stockholm, Sweden; Department of Biomolecular Science, Section of Physiology, University of Urbino, Campus Scientifico Enrico Mattei, via Ca' le Suore 2, I-61029 Urbino, Italy; Observatorio Cubano de Neurociencias, Grupo Bohío-Estudio, Zayas 50, 62100 Yaguajay, Cuba.
| | - M Frinchi
- Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Corso Tukory 129, 90134 Palermo, Italy.
| | - V Verdi
- Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Corso Tukory 129, 90134 Palermo, Italy.
| | - K Fuxe
- Karolinska Instituet, Department of Neuroscience, Retzius väg 8, 17177 Stockholm, Sweden.
| | - N Belluardo
- Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Corso Tukory 129, 90134 Palermo, Italy.
| | - G Mudò
- Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Corso Tukory 129, 90134 Palermo, Italy.
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Pediani JD, Ward RJ, Godin AG, Marsango S, Milligan G. Dynamic Regulation of Quaternary Organization of the M1 Muscarinic Receptor by Subtype-selective Antagonist Drugs. J Biol Chem 2016; 291:13132-46. [PMID: 27080256 PMCID: PMC4933229 DOI: 10.1074/jbc.m115.712562] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Indexed: 12/14/2022] Open
Abstract
Although rhodopsin-like G protein-coupled receptors can exist as both monomers and non-covalently associated dimers/oligomers, the steady-state proportion of each form and whether this is regulated by receptor ligands are unknown. Herein we address these topics for the M1 muscarinic acetylcholine receptor, a key molecular target for novel cognition enhancers, by using spatial intensity distribution analysis. This method can measure fluorescent particle concentration and assess oligomerization states of proteins within defined regions of living cells. Imaging and analysis of the basolateral surface of cells expressing some 50 molecules·μm−2 human muscarinic M1 receptor identified a ∼75:25 mixture of receptor monomers and dimers/oligomers. Both sustained and shorter term treatment with the selective M1 antagonist pirenzepine resulted in a large shift in the distribution of receptor species to favor the dimeric/oligomeric state. Although sustained treatment with pirenzepine also resulted in marked up-regulation of the receptor, simple mass action effects were not the basis for ligand-induced stabilization of receptor dimers/oligomers. The related antagonist telenzepine also produced stabilization and enrichment of the M1 receptor dimer population, but the receptor subtype non-selective antagonists atropine and N-methylscopolamine did not. In contrast, neither pirenzepine nor telenzepine altered the quaternary organization of the related M3 muscarinic receptor. These data provide unique insights into the selective capacity of receptor ligands to promote and/or stabilize receptor dimers/oligomers and demonstrate that the dynamics of ligand regulation of the quaternary organization of G protein-coupled receptors is markedly more complex than previously appreciated. This may have major implications for receptor function and behavior.
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Affiliation(s)
- John D Pediani
- From the Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom and
| | - Richard J Ward
- From the Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom and
| | - Antoine G Godin
- Institut d'Optique and CNRS, Laboratoire Photonique, Numérique et Nanosciences (LP2N) and Université de Bordeaux, LP2N, F-33405, UMR 5298, 33405 Talence Cedex, France
| | - Sara Marsango
- From the Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom and
| | - Graeme Milligan
- From the Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom and
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18
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Aslanoglou D, Alvarez-Curto E, Marsango S, Milligan G. Distinct Agonist Regulation of Muscarinic Acetylcholine M2-M3 Heteromers and Their Corresponding Homomers. J Biol Chem 2015; 290:14785-96. [PMID: 25918156 PMCID: PMC4505543 DOI: 10.1074/jbc.m115.649079] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Indexed: 01/01/2023] Open
Abstract
Each subtype of the muscarinic receptor family of G protein-coupled receptors is activated by similar concentrations of the neurotransmitter acetylcholine or closely related synthetic analogs such as carbachol. However, pharmacological selectivity can be generated by the introduction of a pair of mutations to produce Receptor Activated Solely by Synthetic Ligand (RASSL) forms of muscarinic receptors. These display loss of potency for acetylcholine/carbachol alongside a concurrent gain in potency for the ligand clozapine N-oxide. Co-expression of a form of wild type human M2 and a RASSL variant of the human M3 receptor resulted in concurrent detection of each of M2-M2 and M3-M3 homomers alongside M2-M3 heteromers at the surface of stably transfected Flp-InTM T-RExTM 293 cells. In this setting occupancy of the receptors with a muscarinic antagonist was without detectable effect on any of the muscarinic oligomers. However, selective agonist occupancy of the M2 receptor resulted in enhanced M2-M2 homomer interactions but decreased M2-M3 heteromer interactions. By contrast, selective activation of the M3 RASSL receptor did not significantly alter either M3-M3 homomer or M2-M3 heteromer interactions. Selectively targeting closely related receptor oligomers may provide novel therapeutic opportunities.
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Affiliation(s)
- Despoina Aslanoglou
- From the Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Elisa Alvarez-Curto
- From the Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Sara Marsango
- From the Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Graeme Milligan
- From the Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
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Liste MJV, Caltabiano G, Ward RJ, Alvarez-Curto E, Marsango S, Milligan G. The molecular basis of oligomeric organization of the human M3 muscarinic acetylcholine receptor. Mol Pharmacol 2015; 87:936-53. [PMID: 25769304 DOI: 10.1124/mol.114.096925] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 03/13/2015] [Indexed: 11/22/2022] Open
Abstract
G protein-coupled receptors, including the M3 muscarinic acetylcholine receptor, can form homo-oligomers. However, the basis of these interactions and the overall organizational structure of such oligomers are poorly understood. Combinations of site-directed mutagenesis and homogenous time-resolved fluorescence resonance energy transfer studies that assessed interactions between receptor protomers at the surface of transfected cells indicated important contributions of regions of transmembrane domains I, IV, V, VI, and VII as well as intracellular helix VIII to the overall organization. Molecular modeling studies based on both these results and an X-ray structure of the inactive state of the M3 receptor bound by the antagonist/inverse agonist tiotropium were then employed. The results could be accommodated fully by models in which a proportion of the cell surface M3 receptor population is a tetramer with rhombic, but not linear, orientation. This is consistent with previous studies based on spectrally resolved, multiphoton fluorescence resonance energy transfer. Modeling studies furthermore suggest an important role for molecules of cholesterol at the dimer + dimer interface of the tetramer, which is consistent with the presence of cholesterol at key locations in many G protein-coupled receptor crystal structures. Mutants that displayed disrupted quaternary organization were often poorly expressed and showed immature N-glycosylation. Sustained treatment of cells expressing such mutants with the muscarinic receptor inverse agonist atropine increased cellular levels and restored both cell surface delivery and quaternary organization to many of the mutants. These observations suggest that organization as a tetramer may occur before plasma membrane delivery and may be a key step in cellular quality control assessment.
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Affiliation(s)
- María José Varela Liste
- Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom (M.J.V.L., G.C., R.J.W., E.A.-C., S.M., G.M.), and Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain (G.C.)
| | - Gianluigi Caltabiano
- Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom (M.J.V.L., G.C., R.J.W., E.A.-C., S.M., G.M.), and Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain (G.C.)
| | - Richard J Ward
- Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom (M.J.V.L., G.C., R.J.W., E.A.-C., S.M., G.M.), and Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain (G.C.)
| | - Elisa Alvarez-Curto
- Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom (M.J.V.L., G.C., R.J.W., E.A.-C., S.M., G.M.), and Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain (G.C.)
| | - Sara Marsango
- Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom (M.J.V.L., G.C., R.J.W., E.A.-C., S.M., G.M.), and Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain (G.C.)
| | - Graeme Milligan
- Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom (M.J.V.L., G.C., R.J.W., E.A.-C., S.M., G.M.), and Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain (G.C.)
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Demonstration of a direct interaction between β2-adrenergic receptor and insulin receptor by BRET and bioinformatics. PLoS One 2014; 9:e112664. [PMID: 25401701 PMCID: PMC4234468 DOI: 10.1371/journal.pone.0112664] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Accepted: 10/06/2014] [Indexed: 12/23/2022] Open
Abstract
Glucose metabolism is under the cooperative regulation of both insulin receptor (IR) and β2-adrenergic receptor (β2AR), which represent the receptor tyrosine kinases (RTKs) and seven transmembrane receptors (7TMRs), respectively. Studies demonstrating cross-talk between these two receptors and their endogenous coexpression have suggested their possible interactions. To evaluate the effect of IR and prospective heteromerization on β2AR properties, we showed that IR coexpression had no effect on the ligand binding properties of β2AR; however, IR reduced β2AR surface expression and accelerated its internalization. Additionally, both receptors displayed a similar distribution pattern with a high degree of colocalization. To test the possible direct interaction between β2AR and IR, we employed quantitative BRET2 saturation and competition assays. Saturation assay data suggested constitutive β2AR and IR homo- and heteromerization. Calculated acceptor/donor (AD50) values as a measure of the relative affinity for homo- and heteromer formation differed among the heteromers that could not be explained by a simple dimer model. In heterologous competition assays, a transient increase in the BRET2 signal with a subsequent hyperbolical decrease was observed, suggesting higher-order heteromer formation. To complement the BRET2 data, we employed the informational spectrum method (ISM), a virtual spectroscopy method to investigate protein-protein interactions. Computational peptide scanning of β2AR and IR identified intracellular domains encompassing residues at the end of the 7th TM domain and C-terminal tail of β2AR and a cytoplasmic part of the IR β chain as prospective interaction domains. ISM further suggested a high probability of heteromer formation and homodimers as basic units engaged in heteromerization. In summary, our data suggest direct interaction and higher-order β2AR:IR oligomer formation, likely comprising heteromers of homodimers.
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Hu J, Hu K, Liu T, Stern MK, Mistry R, Challiss RAJ, Costanzi S, Wess J. Novel structural and functional insights into M3 muscarinic receptor dimer/oligomer formation. J Biol Chem 2013; 288:34777-90. [PMID: 24133207 DOI: 10.1074/jbc.m113.503714] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Class A G protein-coupled receptors (GPCRs) are able to form homodimers and/or oligomeric arrays. We recently proposed, based on bioluminescence resonance energy transfer studies with the M3 muscarinic receptor (M3R), a prototypic class A GPCR, that the M3R is able to form multiple, structurally distinct dimers that are probably transient in nature (McMillin, S. M., Heusel, M., Liu, T., Costanzi, S., and Wess, J. (2011) J. Biol. Chem. 286, 28584-28598). To provide more direct experimental support for this concept, we employed a disulfide cross-linking strategy to trap various M3R dimeric species present in a native lipid environment (transfected COS-7 cells). Disulfide cross-linking studies were carried out with many mutant M3Rs containing single cysteine (Cys) substitutions within two distinct cytoplasmic M3R regions, the C-terminal portion of the second intracellular loop (i2) and helix H8 (H8). The pattern of cross-links that we obtained, in combination with molecular modeling studies, was consistent with the existence of two structurally distinct M3R dimer interfaces, one involving i2/i2 contacts (TM4-TM5-i2 interface) and the other one characterized by H8-H8 interactions (TM1-TM2-H8 interface). Specific H8-H8 disulfide cross-links led to significant impairments in M3R-mediated G protein activation, suggesting that changes in the structural orientation or mobility of H8 are critical for efficient receptor-G protein coupling. Our findings provide novel structural and functional insights into the mechanisms involved in M3R dimerization (oligomerization). Because the M3R shows a high degree of sequence similarity with many other class A GPCRs, our findings should be of considerable general interest.
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Affiliation(s)
- Jianxin Hu
- From the Molecular Signaling Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Bethesda, Maryland 20892
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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
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23
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Herrick-Davis K, Grinde E, Cowan A, Mazurkiewicz JE. Fluorescence correlation spectroscopy analysis of serotonin, adrenergic, muscarinic, and dopamine receptor dimerization: the oligomer number puzzle. Mol Pharmacol 2013; 84:630-42. [PMID: 23907214 DOI: 10.1124/mol.113.087072] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The issue of G protein-coupled receptor (GPCR) oligomer status has not been resolved. Although many studies have provided evidence in favor of receptor-receptor interactions, there is no consensus as to the exact oligomer size of class A GPCRs. Previous studies have reported monomers, dimers, tetramers, and higher-order oligomers. In the present study, this issue was examined using fluorescence correlation spectroscopy (FCS) with photon counting histogram (PCH) analysis, a sensitive method for monitoring diffusion and oligomer size of plasma membrane proteins. Six different class A GPCRs were selected from the serotonin (5-HT2A), adrenergic (α1b-AR and β2-AR), muscarinic (M1 and M2), and dopamine (D1) receptor families. Each GPCR was C-terminally labeled with green fluorescent protein (GFP) or yellow fluorescent protein (YFP) and expressed in human embryonic kidney 293 cells. FCS provided plasma membrane diffusion coefficients on the order of 7.5 × 10(-9) cm(2)/s. PCH molecular brightness analysis was used to determine the GPCR oligomer size. Known monomeric (CD-86) and dimeric (CD-28) receptors with GFP and YFP tags were used as controls to determine the molecular brightness of monomers and dimers. PCH analysis of fluorescence-tagged GPCRs revealed molecular brightness values that were twice the monomeric controls and similar to the dimeric controls. Reduced χ(2) analyses of the PCH data best fit a model for a homogeneous population of homodimers, without tetramers or higher-order oligomers. The homodimer configuration was unaltered by agonist treatment and was stable over a 10-fold range of receptor expression level. The results of this study demonstrate that biogenic amine receptors freely diffusing within the plasma membrane are predominantly homodimers.
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Affiliation(s)
- Katharine Herrick-Davis
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, New York (K.H.-D., E.G., J.E.M.); and Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, Connecticut (A.C.)
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24
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Functional significance of serotonin receptor dimerization. Exp Brain Res 2013; 230:375-86. [PMID: 23811735 DOI: 10.1007/s00221-013-3622-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2013] [Accepted: 06/10/2013] [Indexed: 01/01/2023]
Abstract
The original model of G-protein activation by a single G-protein-coupled receptor (GPCR) is giving way to a new model, wherein two protomers of a GPCR dimer interact with a single G-protein. This article will review the evidence suggesting that 5-HT receptors form dimers/oligomers and will compare the findings with the results obtained from the studies with other biogenic amine receptors. Topics to be covered include the origin or biogenesis of dimer formation, potential dimer interface(s), and oligomer size (dimer vs. tetramer or higher order). The functional significance will be discussed in terms of G-protein activation following ligand binding to one or two protomers in a dimeric structure, the formation of heterodimers, and the development of bivalent ligands.
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25
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Ockenga W, Kühne S, Bocksberger S, Banning A, Tikkanen R. Non-neuronal functions of the m2 muscarinic acetylcholine receptor. Genes (Basel) 2013; 4:171-97. [PMID: 24705159 PMCID: PMC3899973 DOI: 10.3390/genes4020171] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 03/10/2013] [Accepted: 03/25/2013] [Indexed: 12/26/2022] Open
Abstract
Acetylcholine is an important neurotransmitter whose effects are mediated by two classes of receptors. The nicotinic acetylcholine receptors are ion channels, whereas the muscarinic receptors belong to the large family of G protein coupled seven transmembrane helix receptors. Beyond its function in neuronal systems, it has become evident that acetylcholine also plays an important role in non-neuronal cells such as epithelial and immune cells. Furthermore, many cell types in the periphery are capable of synthesizing acetylcholine and express at least some of the receptors. In this review, we summarize the non-neuronal functions of the muscarinic acetylcholine receptors, especially those of the M2 muscarinic receptor in epithelial cells. We will review the mechanisms of signaling by the M2 receptor but also the cellular trafficking and ARF6 mediated endocytosis of this receptor, which play an important role in the regulation of signaling events. In addition, we provide an overview of the M2 receptor in human pathological conditions such as autoimmune diseases and cancer.
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Affiliation(s)
- Wymke Ockenga
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany.
| | - Sina Kühne
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany.
| | - Simone Bocksberger
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany.
| | - Antje Banning
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany.
| | - Ritva Tikkanen
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany.
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26
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Nenasheva TA, Neary M, Mashanov GI, Birdsall NJ, Breckenridge RA, Molloy JE. Abundance, distribution, mobility and oligomeric state of M₂ muscarinic acetylcholine receptors in live cardiac muscle. J Mol Cell Cardiol 2013; 57:129-36. [PMID: 23357106 PMCID: PMC3605596 DOI: 10.1016/j.yjmcc.2013.01.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 12/21/2012] [Accepted: 01/11/2013] [Indexed: 11/10/2022]
Abstract
M2 muscarinic acetylcholine receptors modulate cardiac rhythm via regulation of the inward potassium current. To increase our understanding of M2 receptor physiology we used Total Internal Reflection Fluorescence Microscopy to visualize individual receptors at the plasma membrane of transformed CHO(M2) cells, a cardiac cell line (HL-1), primary cardiomyocytes and tissue slices from pre- and post-natal mice. Receptor expression levels between individual cells in dissociated cardiomyocytes and heart slices were highly variable and only 10% of murine cardiomyocytes expressed muscarinic receptors. M2 receptors were evenly distributed across individual cells and their density in freshly isolated embryonic cardiomyocytes was ~1μm(-2), increasing at birth (to ~3μm(-2)) and decreasing back to ~1μm(-2) after birth. M2 receptors were primarily monomeric but formed reversible dimers. They diffused freely at the plasma membrane, moving approximately 4-times faster in heart slices than in cultured cardiomyocytes. Knowledge of receptor density and mobility has allowed receptor collision rate to be modeled by Monte Carlo simulations. Our estimated encounter rate of 5-10 collisions per second, may explain the latency between acetylcholine application and GIRK channel opening.
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Affiliation(s)
- Tatiana A. Nenasheva
- Division of Physical Biochemistry, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Marianne Neary
- Division of Developmental Biology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Gregory I. Mashanov
- Division of Physical Biochemistry, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Nigel J.M. Birdsall
- Division of Physical Biochemistry, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Ross A. Breckenridge
- Division of Developmental Biology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Justin E. Molloy
- Division of Physical Biochemistry, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
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27
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Hollenhorst MI, Lips KS, Wolff M, Wess J, Gerbig S, Takats Z, Kummer W, Fronius M. Luminal cholinergic signalling in airway lining fluid: a novel mechanism for activating chloride secretion via Ca²⁺-dependent Cl⁻ and K⁺ channels. Br J Pharmacol 2012; 166:1388-402. [PMID: 22300281 DOI: 10.1111/j.1476-5381.2012.01883.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND AND PURPOSE Recent studies detected the expression of proteins involved in cholinergic metabolism in airway epithelial cells, although the function of this non-neuronal cholinergic system is not known in detail. Thus, this study focused on the effect of luminal ACh as a regulator of transepithelial ion transport in epithelial cells. EXPERIMENTAL APPROACH RT-PCR experiments were performed using mouse tracheal epithelial cells for ChAT and organic cation transporter (OCT) transcripts. Components of tracheal airway lining fluid were analysed with desorption electrospray ionization (DESI) MS. Effects of nicotine on mouse tracheal epithelial ion transport were examined with Ussing-chamber experiments. KEY RESULTS Transcripts encoding ChAT and OCT1-3 were detected in mouse tracheal epithelial cells. The DESI experiments identified ACh in the airway lining fluid. Luminal ACh induced an immediate, dose-dependent increase in the transepithelial ion current (EC₅₀: 23.3 µM), characterized by a transient peak and sustained plateau current. This response was not affected by the Na⁺-channel inhibitor amiloride. The Cl⁻-channel inhibitor niflumic acid or the K⁺-channel blocker Ba²⁺ attenuated the ACh effect. The calcium ionophore A23187 mimicked the ACh effect. Luminal nicotine or muscarine increased the ion current. Experiments with receptor gene-deficient animals revealed the participation of muscarinic receptor subtypes M₁ and M₃. CONCLUSIONS AND IMPLICATIONS The presence of luminal ACh and activation of transepithelial ion currents by luminal ACh receptors identifies a novel non-neuronal cholinergic pathway in the airway lining fluid. This pathway could represent a novel drug target in the airways.
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Affiliation(s)
- Monika I Hollenhorst
- Institute of Animal Physiology, Justus-Liebig-University Giessen, Giessen, Germany
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28
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Herrick-Davis K, Grinde E, Lindsley T, Cowan A, Mazurkiewicz JE. Oligomer size of the serotonin 5-hydroxytryptamine 2C (5-HT2C) receptor revealed by fluorescence correlation spectroscopy with photon counting histogram analysis: evidence for homodimers without monomers or tetramers. J Biol Chem 2012; 287:23604-14. [PMID: 22593582 PMCID: PMC3390635 DOI: 10.1074/jbc.m112.350249] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 04/05/2012] [Indexed: 11/06/2022] Open
Abstract
Fluorescence correlation spectroscopy (FCS) and photon counting histogram (PCH) are techniques with single molecule sensitivity that are well suited for examining the biophysical properties of protein complexes in living cells. In the present study, FCS and PCH were applied to determine the diffusion coefficient and oligomeric size of G-protein-coupled receptors. FCS was used to record fluctuations in fluorescence intensity arising from fluorescence-tagged 5-hydroxytryptamine 2C (5-HT(2C)) receptors diffusing within the plasma membrane of HEK293 cells and rat hippocampal neurons. Autocorrelation analysis yielded diffusion coefficients ranging from 0.8 to 1.2 μm(2)/s for fluorescence-tagged receptors. Because the molecular brightness of a fluorescent protein is directly proportional to the number of fluorescent proteins traveling together within a protein complex, it can be used to determine the oligomeric size of the protein complex. FCS and PCH analysis of fluorescence-tagged 5-HT(2C) receptors provided molecular brightness values that were twice that of GFP and YFP monomeric controls, similar to a dimeric GFP control, and unaltered by 5-HT. Bimolecular fluorescence complementation of the N- and C-terminal halves of YFP attached to 5-HT(2C) receptors was observed in endoplasmic reticulum/Golgi and plasma membranes with a brightness equal to monomeric YFP. When GFP-tagged 5-HT(2C) receptors were co-expressed with a large excess of untagged, non-fluorescent 5-HT(2C) receptors, the molecular brightness was reduced by half. PCH analysis of the FCS data were best described by a one-component dimer model without monomers or tetramers. Therefore, it is concluded that 5-HT(2C) receptors freely diffusing within the plasma membrane are dimeric.
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MESH Headings
- Animals
- Cell Membrane/drug effects
- Cell Membrane/metabolism
- Cells, Cultured
- Diffusion/drug effects
- Endoplasmic Reticulum/metabolism
- Fluorescence
- Golgi Apparatus/metabolism
- Green Fluorescent Proteins/chemistry
- Green Fluorescent Proteins/genetics
- Green Fluorescent Proteins/metabolism
- HEK293 Cells
- Hippocampus/cytology
- Humans
- Luminescent Proteins/chemistry
- Luminescent Proteins/genetics
- Luminescent Proteins/metabolism
- Microscopy, Confocal
- Mutation
- Neurons/cytology
- Neurons/drug effects
- Neurons/metabolism
- Protein Multimerization
- Protein Transport/drug effects
- Rats
- Rats, Sprague-Dawley
- Receptor, Serotonin, 5-HT2C/chemistry
- Receptor, Serotonin, 5-HT2C/genetics
- Receptor, Serotonin, 5-HT2C/metabolism
- Serotonin/pharmacology
- Spectrometry, Fluorescence/methods
- Transfection
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Affiliation(s)
- Katharine Herrick-Davis
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, New York 12208, USA.
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29
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Fuxe K, Borroto-Escuela DO, Romero-Fernandez W, Diaz-Cabiale Z, Rivera A, Ferraro L, Tanganelli S, Tarakanov AO, Garriga P, Narváez JA, Ciruela F, Guescini M, Agnati LF. Extrasynaptic neurotransmission in the modulation of brain function. Focus on the striatal neuronal-glial networks. Front Physiol 2012; 3:136. [PMID: 22675301 PMCID: PMC3366473 DOI: 10.3389/fphys.2012.00136] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Accepted: 04/23/2012] [Indexed: 12/20/2022] Open
Abstract
Extrasynaptic neurotransmission is an important short distance form of volume transmission (VT) and describes the extracellular diffusion of transmitters and modulators after synaptic spillover or extrasynaptic release in the local circuit regions binding to and activating mainly extrasynaptic neuronal and glial receptors in the neuroglial networks of the brain. Receptor-receptor interactions in G protein-coupled receptor (GPCR) heteromers play a major role, on dendritic spines and nerve terminals including glutamate synapses, in the integrative processes of the extrasynaptic signaling. Heteromeric complexes between GPCR and ion-channel receptors play a special role in the integration of the synaptic and extrasynaptic signals. Changes in extracellular concentrations of the classical synaptic neurotransmitters glutamate and GABA found with microdialysis is likely an expression of the activity of the neuron-astrocyte unit of the brain and can be used as an index of VT-mediated actions of these two neurotransmitters in the brain. Thus, the activity of neurons may be functionally linked to the activity of astrocytes, which may release glutamate and GABA to the extracellular space where extrasynaptic glutamate and GABA receptors do exist. Wiring transmission (WT) and VT are fundamental properties of all neurons of the CNS but the balance between WT and VT varies from one nerve cell population to the other. The focus is on the striatal cellular networks, and the WT and VT and their integration via receptor heteromers are described in the GABA projection neurons, the glutamate, dopamine, 5-hydroxytryptamine (5-HT) and histamine striatal afferents, the cholinergic interneurons, and different types of GABA interneurons. In addition, the role in these networks of VT signaling of the energy-dependent modulator adenosine and of endocannabinoids mainly formed in the striatal projection neurons will be underlined to understand the communication in the striatal cellular networks.
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Affiliation(s)
- Kjell Fuxe
- Department of Neuroscience, Karolinska InstitutetStockholm, Sweden
| | | | | | - Zaida Diaz-Cabiale
- Department of Physiology, School of Medicine, University of MálagaMálaga, Spain
| | - Alicia Rivera
- Department of Cell Biology, Faculty of Sciences, University of MálagaMálaga, Spain
| | - Luca Ferraro
- Pharmacology Section, Department of Clinical and Experimental Medicine, University of FerraraFerrara, Italy
| | - Sergio Tanganelli
- Pharmacology Section, Department of Clinical and Experimental Medicine, University of FerraraFerrara, Italy
| | - Alexander O. Tarakanov
- Russian Academy of Sciences, St. Petersburg Institute for Informatics and AutomationSaint Petersburg, Russia
| | - Pere Garriga
- Departament d’Enginyeria Química, Centre de Biotecnologia Molecular, Universitat Politècnica de CatalunyaBarcelona, Spain
| | - José Angel Narváez
- Department of Physiology, School of Medicine, University of MálagaMálaga, Spain
| | - Francisco Ciruela
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental, Universitat de BarcelonaBarcelona, Spain
| | - Michele Guescini
- Department of Biomolecular Sciences, University of Urbino “CarloBo”Urbino, Italy
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30
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Influence of MT7 toxin on the oligomerization state of the M1 muscarinic receptor1. Biol Cell 2012; 102:409-20. [DOI: 10.1042/bc20090171] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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31
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Drinovec L, Kubale V, Nøhr Larsen J, Vrecl M. Mathematical models for quantitative assessment of bioluminescence resonance energy transfer: application to seven transmembrane receptors oligomerization. Front Endocrinol (Lausanne) 2012; 3:104. [PMID: 22973259 PMCID: PMC3428587 DOI: 10.3389/fendo.2012.00104] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 08/08/2012] [Indexed: 11/24/2022] Open
Abstract
The idea that seven transmembrane receptors (7TMRs; also designated G-protein coupled receptors, GPCRs) might form dimers or higher order oligomeric complexes was formulated more than 20 years ago and has been intensively studied since then. In the last decade, bioluminescence resonance energy transfer (BRET) has been one of the most frequently used biophysical methods for studying 7TMRs oligomerization. This technique enables monitoring physical interactions between protein partners in living cells fused to donor and acceptor moieties. It relies on non-radiative transfer of energy between donor and acceptor, depending on their intermolecular distance (1-10 nm) and relative orientation. Results derived from BRET-based techniques are very persuasive; however, they need appropriate controls and critical interpretation. To overcome concerns about the specificity of BRET-derived results, a set of experiments has been proposed, including negative control with a non-interacting receptor or protein, BRET dilution, saturation, and competition assays. This article presents the theoretical background behind BRET assays, then outlines mathematical models for quantitative interpretation of BRET saturation and competition assay results, gives examples of their utilization and discusses the possibilities of quantitative analysis of data generated with other RET-based techniques.
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32
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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.
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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:
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33
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Abstract
Knowledge of the mechanisms responsible for the trafficking of neurotransmitter receptors away from the cell surface is of obvious importance in understanding what regulates their expression and function. This chapter will focus on the mechanisms responsible for the internalization and degradation of muscarinic receptors. There are both receptor subtype-specific and cell-type specific differences in muscarinic receptor trafficking. Studies on muscarinic receptor trafficking both in cells in culture and in vivo will be described, and the potential physiological consequences of this trafficking will be discussed.
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Affiliation(s)
- Cindy Reiner
- Department of Pharmacology, University of Washington, 357750, Seattle, WA 98195-7750, USA
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34
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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.
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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
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35
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Hu J, Thor D, Zhou Y, Liu T, Wang Y, McMillin SM, Mistry R, Challiss RAJ, Costanzi S, Wess J. Structural aspects of M₃ muscarinic acetylcholine receptor dimer formation and activation. FASEB J 2011; 26:604-16. [PMID: 22031716 DOI: 10.1096/fj.11-191510] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
To explore the structural mechanisms underlying the assembly and activation of family A GPCR dimers, we used the rat M(3) muscarinic acetylcholine receptor (M3R) as a model system. Studies with Cys-substituted mutant M3Rs expressed in COS-7 cells led to the identification of several mutant M3Rs that exclusively existed as cross-linked dimers under oxidizing conditions. The cross-linked residues were located at the bottom of transmembrane domain 5 (TM5) and within the N-terminal portion of the third intracellular loop (i3 loop). Studies with urea-stripped membranes demonstrated that M3R disulfide cross-linking did not require the presence of heterotrimeric G proteins. Molecular modeling studies indicated that the cross-linking data were in excellent agreement with the existence of a low-energy M3R dimer characterized by a TM5-TM5 interface. [(35)S]GTPγS binding/Gα(q/11) immunoprecipitation assays revealed that an M3R dimer that was cross-linked within the N-terminal portion of the i3 loop (264C) was functionally severely impaired (∼50% reduction in receptor-G-protein coupling, as compared to control M3R). These data support the novel concept that agonist-induced activation of M3R dimers requires a conformational change of the N-terminal segment of the i3 loop. Given the high degree of structural homology among family A GPCRs, these findings should be of broad significance.
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Affiliation(s)
- Jianxin Hu
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892-0810, USA
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36
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Servent D, Blanchet G, Mourier G, Marquer C, Marcon E, Fruchart-Gaillard C. Muscarinic toxins. Toxicon 2011; 58:455-63. [PMID: 21906611 DOI: 10.1016/j.toxicon.2011.08.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 07/12/2011] [Accepted: 08/08/2011] [Indexed: 12/15/2022]
Abstract
Muscarinic toxins isolated from the venom of Dendroaspis snakes may interact with a high affinity, large selectivity and various functional properties with muscarinic receptors. Therefore, these toxins are invaluable tools for studying the physiological role, molecular functioning and structural organization of the five subtypes of these G-Protein Coupled Receptors. We review the data on the most relevant results dealing with the isolation/identification, mode of action, structure/function and exploitation of these toxins and finally highlight the unresolved issues related to their pharmacological studies.
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Affiliation(s)
- Denis Servent
- CEA, Institute of Biology and Technology, Service d'Ingénierie Moléculaire des Protéines, Gif-sur-Yvette 91191, France.
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McMillin SM, Heusel M, Liu T, Costanzi S, Wess J. Structural basis of M3 muscarinic receptor dimer/oligomer formation. J Biol Chem 2011; 286:28584-98. [PMID: 21685385 PMCID: PMC3151100 DOI: 10.1074/jbc.m111.259788] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Indexed: 01/03/2023] Open
Abstract
Class A G protein-coupled receptors (GPCRs) are known to form dimers and/or oligomeric arrays in vitro and in vivo. These complexes are thought to play important roles in modulating class A GPCR function. Many studies suggest that residues located on the "outer" (lipid-facing) surface of the transmembrane (TM) receptor core are critically involved in the formation of class A receptor dimers (oligomers). However, no clear consensus has emerged regarding the identity of the TM helices or TM subsegments involved in this process. To shed light on this issue, we have used the M(3) muscarinic acetylcholine receptor (M3R), a prototypic class A GPCR, as a model system. Using a comprehensive and unbiased approach, we subjected all outward-facing residues (70 amino acids total) of the TM helical bundle (TM1-7) of the M3R to systematic alanine substitution mutagenesis. We then characterized the resulting mutant receptors in radioligand binding and functional studies and determined their ability to form dimers (oligomers) in bioluminescence resonance energy transfer saturation assays. We found that M3R/M3R interactions are not dependent on the presence of one specific structural motif but involve the outer surfaces of multiple TM subsegments (TM1-5 and -7) located within the central and endofacial portions of the TM receptor core. Moreover, we demonstrated that the outward-facing surfaces of most TM helices play critical roles in proper receptor folding and/or function. Guided by the bioluminescence resonance energy transfer data, molecular modeling studies suggested the existence of multiple dimeric/oligomeric M3R arrangements, which may exist in a dynamic equilibrium. Given the high structural homology found among all class A GPCRs, our results should be of considerable general relevance.
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Affiliation(s)
| | | | - Tong Liu
- From the Laboratory of Bioorganic Chemistry and
| | - Stefano Costanzi
- Laboratory of Biological Modeling, NIDDK, National Institutes of Health, Bethesda, Maryland 20892
| | - Jürgen Wess
- From the Laboratory of Bioorganic Chemistry and
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Kasai RS, Suzuki KGN, Prossnitz ER, Koyama-Honda I, Nakada C, Fujiwara TK, Kusumi A. Full characterization of GPCR monomer-dimer dynamic equilibrium by single molecule imaging. ACTA ACUST UNITED AC 2011; 192:463-80. [PMID: 21300851 PMCID: PMC3101103 DOI: 10.1083/jcb.201009128] [Citation(s) in RCA: 256] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Receptor dimerization is important for many signaling pathways. However, the monomer-dimer equilibrium has never been fully characterized for any receptor with a 2D equilibrium constant as well as association/dissociation rate constants (termed super-quantification). Here, we determined the dynamic equilibrium for the N-formyl peptide receptor (FPR), a chemoattractant G protein-coupled receptor (GPCR), in live cells at 37°C by developing a single fluorescent-molecule imaging method. Both before and after liganding, the dimer-monomer 2D equilibrium is unchanged, giving an equilibrium constant of 3.6 copies/µm(2), with a dissociation and 2D association rate constant of 11.0 s(-1) and 3.1 copies/µm(2)s(-1), respectively. At physiological expression levels of ∼2.1 receptor copies/µm(2) (∼6,000 copies/cell), monomers continually convert into dimers every 150 ms, dimers dissociate into monomers in 91 ms, and at any moment, 2,500 and 3,500 receptor molecules participate in transient dimers and monomers, respectively. Not only do FPR dimers fall apart rapidly, but FPR monomers also convert into dimers very quickly.
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Affiliation(s)
- Rinshi S Kasai
- Membrane Mechanisms Project, International Cooperative Research Project, Kyoto University, Shougoin, Kyoto 606-8507, Japan
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39
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Marquer C, Fruchart-Gaillard C, Letellier G, Marcon E, Mourier G, Zinn-Justin S, Ménez A, Servent D, Gilquin B. Structural model of ligand-G protein-coupled receptor (GPCR) complex based on experimental double mutant cycle data: MT7 snake toxin bound to dimeric hM1 muscarinic receptor. J Biol Chem 2011; 286:31661-75. [PMID: 21685390 DOI: 10.1074/jbc.m111.261404] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The snake toxin MT7 is a potent and specific allosteric modulator of the human M1 muscarinic receptor (hM1). We previously characterized by mutagenesis experiments the functional determinants of the MT7-hM1 receptor interaction (Fruchart-Gaillard, C., Mourier, G., Marquer, C., Stura, E., Birdsall, N. J., and Servent, D. (2008) Mol. Pharmacol. 74, 1554-1563) and more recently collected evidence indicating that MT7 may bind to a dimeric form of hM1 (Marquer, C., Fruchart-Gaillard, C., Mourier, G., Grandjean, O., Girard, E., le Maire, M., Brown, S., and Servent, D. (2010) Biol. Cell 102, 409-420). To structurally characterize the MT7-hM1 complex, we adopted a strategy combining double mutant cycle experiments and molecular modeling calculations. First, thirty-three ligand-receptor proximities were identified from the analysis of sixty-one double mutant binding affinities. Several toxin residues that are more than 25 Å apart still contact the same residues on the receptor. As a consequence, attempts to satisfy all the restraints by docking the toxin onto a single receptor failed. The toxin was then positioned onto two receptors during five independent flexible docking simulations. The different possible ligand and receptor extracellular loop conformations were described by performing simulations in explicit solvent. All the docking calculations converged to the same conformation of the MT7-hM1 dimer complex, satisfying the experimental restraints and in which (i) the toxin interacts with the extracellular side of the receptor, (ii) the tips of MT7 loops II and III contact one hM1 protomer, whereas the tip of loop I binds to the other protomer, and (iii) the hM1 dimeric interface involves the transmembrane helices TM6 and TM7. These results structurally support the high affinity and selectivity of the MT7-hM1 interaction and highlight the atypical mode of interaction of this allosteric ligand on its G protein-coupled receptor target.
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Affiliation(s)
- Catherine Marquer
- Laboratoire de Biologie Structurale et Radiobiologie, Service de Bioénergétique, Biologie Structurale et Mécanismes (SB2SM), CNRS Unité de Recherche Associée 2096, Gif sur Yvette F-91191, France
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40
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Chung KM, Cheng JH, Suen CS, Huang CH, Tsai CH, Huang LH, Chen YR, Wang AHJ, Jiaang WT, Hwang MJ, Chen X. The dimeric transmembrane domain of prolyl dipeptidase DPP-IV contributes to its quaternary structure and enzymatic activities. Protein Sci 2011; 19:1627-38. [PMID: 20572019 DOI: 10.1002/pro.443] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Dipeptidyl peptidase IV (DPP-IV) is a drug target in the treatment of human type II diabetes. It is a type II membrane protein with a single transmembrane domain (TMD) anchoring the extracellular catalytic domain to the membrane. DPP-IV is active as a dimer, with two dimer interacting surfaces located extracellularly. In this study, we demonstrate that the TM of DPP-IV promotes DPP-IV dimerization and rescues monomeric DPP-IV mutants into partial dimers, which is specific and irreplaceable by TMs of other type II membrane proteins. By bioluminescence resonance energy transfer (BRET) and peptide electrophoresis, we found that the TM domain of DPP-IV is dimerized in mammalian cells and in vitro. The TM dimer interaction is very stable, based on our results with TM site-directed mutagenesis. None of the mutations, including the introduction of two prolines, resulted in their complete disruption to monomers. However, these TM proline mutations result in a significant reduction of DPP-IV enzymatic activity, comparable to what is found with mutations near the active site. A systematic analysis of TM structures deposited in the Protein Data Bank showed that prolines in the TM generally produce much bigger kinking angles than occur in nonproline-containing TMs. Thus, the proline-dependent reduction in enzyme activity may result from propagated conformational changes from the TM to the extracellular active site. Our results demonstrate that TM dimerization and conformation contribute significantly to the structure and activity of DPP-IV. Optimal enzymatic activity of DPP-IV requires an optimal interaction of all three dimer interfaces, including its TM.
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Affiliation(s)
- Kuei-Min Chung
- Division of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Zhu Nan town, Miaoli County, Taiwan, Republic of China
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41
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Beltrame SP, Auger SR, Bilder CR, Waldner CI, Goin JC. Modulation of M(2) muscarinic receptor-receptor interaction by immunoglobulin G antibodies from Chagas' disease patients. Clin Exp Immunol 2011; 164:170-9. [PMID: 21391990 DOI: 10.1111/j.1365-2249.2011.04370.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Circulating immunoglobulin (Ig)G antibodies against M(2) muscarinic acetylcholine receptors (M(2) mAChR) have been implicated in Chagas' disease (ChD) pathophysiology. These antibodies bind to and activate their target receptor, displaying agonist-like activity through an unclear mechanism. This study tested the ability of serum anti-M(2) mAChR antibodies from chronic ChD patients to modulate M(2) muscarinic receptor-receptor interaction by bioluminescence resonance energy transfer (BRET). Human embryonic kidney (HEK) 293 cells co-expressing fusion proteins M(2) mAChR-Renilla luciferase (RLuc) and M(2) mAChR-yellow fluorescent protein (YFP) were exposed to the serum IgG fraction from ChD patients, and BRET between RLuc and YFP was assessed by luminometry. Unlike serum IgG from healthy subjects and conventional muscarinic ligands, ChD IgG promoted a time- and concentration-dependent increase in the BRET signal. This effect neither required cellular integrity nor occurred as a consequence of receptor activation. Enhancement of M(2) receptor-receptor interaction by ChD IgG was receptor subtype-specific and mediated by the recognition of the second extracellular loop of the M(2) mAChR. The monovalent Fab fragment derived from ChD IgG was unable to reproduce the effect of the native immunoglobulin. However, addition of ChD Fab in the presence of anti-human Fab IgG restored BRET-enhancing activity. These data suggest that the modulatory effect of ChD IgG on M(2) receptor-receptor interaction results from receptor cross-linking by bivalent antibodies.
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Affiliation(s)
- S P Beltrame
- Laboratorio de Farmacología Molecular, Centro de Estudios Farmacológicos y Botánicos (CEFYBO-CONICET-UBA)
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42
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Rosemond E, Rossi M, McMillin SM, Scarselli M, Donaldson JG, Wess J. Regulation of M₃ muscarinic receptor expression and function by transmembrane protein 147. Mol Pharmacol 2010; 79:251-61. [PMID: 21056967 DOI: 10.1124/mol.110.067363] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The M₃ muscarinic acetylcholine receptor (M3R) regulates many fundamental physiological functions. To identify novel M3R-interacting proteins, we used a recently developed yeast two-hybrid screen (split ubiquitin method) to detect interactions among membrane proteins. This screen led to the identification of many novel M3R-associated proteins, including the putative membrane protein transmembrane protein 147 (Tmem147). The amino acid sequence of Tmem147 is highly conserved among mammals, but its physiological roles are unknown at present. We initially demonstrated that Tmem147 could be coimmunoprecipitated with M3Rs in cotransfected mammalian cells (COS-7 cells). Confocal imaging studies showed that Tmem147 was localized to endoplasmic reticulum (ER) membranes and that the Tmem147/M3R interaction occurred in the ER of cotransfected COS-7 cells, resulting in impaired trafficking of the M3R to the cell surface. To study the role of Tmem147 in modulating M3R function in a more physiologically relevant setting, we carried out studies with H508 human colon cancer cells that endogenously express M3Rs and Tmem147. Treatment of H508 cells with carbachol, a hydrolytically stable acetylcholine analog, promoted H508 cell proliferation and activation of the mitogenic kinase, p90RSK. Small interfering RNA-mediated knockdown of Tmem147 expression significantly augmented the stimulatory effects of carbachol on H508 cell proliferation and p90RSK activation. These effects were associated with an increase in the density of cell surface M3Rs. Our data clearly indicate that Tmem147 represents a potent negative regulator of M3R function, most likely by interacting with M3Rs in an intracellular compartment (ER). These findings may lead to new strategies aimed at modulating M3R activity for therapeutic purposes.
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Affiliation(s)
- Erica Rosemond
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland, USA
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43
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van Nassauw L, Timmermans JP. Detailed knowledge of cellular expression of G protein-coupled receptors in the human enteric nervous system is essential for understanding their diverse actions. Neurogastroenterol Motil 2010; 22:959-64. [PMID: 20701687 DOI: 10.1111/j.1365-2982.2010.01575.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
G protein-coupled receptors (GPCRs) comprise a large and diverse superfamily of transmembrane receptors that mediate the functions of an extraordinarily large number of extracellular ligands. They control many major physiological processes and are involved in diverse pathological processes, including gastrointestinal diseases. G protein-coupled receptors are one of the most targeted classes in pharmaceutical drug research. At present, much of our knowledge concerning the expression, distribution and function of GPCRs in the gut has been gleaned from studies performed in experimental models. Data obtained in the human digestive tract, especially in the enteric nervous system, are sparse and incomplete, although enteric neurons have a key position in almost all physiological and pathophysiological processes in the gut. Knowledge of cellular distribution of GPCRs, of regional differences in GPCR expression, and of altered GPCR expression during pathophysiological conditions in the human gut, will lead to a better understanding of GPCR activity, but will also contribute to the development of new drugs. In the current issue of the Journal, Harrington et al. describe the presence and cellular localization of muscarinic receptors in the human colon. Morphologically, orientated studies on the cellular expression of GPCRs in the human gut have to be encouraged, because these studies will yield data that are of therapeutic relevance.
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Affiliation(s)
- L van Nassauw
- Laboratory of Cell Biology & Histology, Department of Veterinary Sciences, University of Antwerp, Antwerpen, Belgium
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44
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The M5 muscarinic acetylcholine receptor third intracellular loop regulates receptor function and oligomerization. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1803:813-25. [DOI: 10.1016/j.bbamcr.2010.04.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 04/01/2010] [Accepted: 04/05/2010] [Indexed: 11/15/2022]
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45
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Alvarez-Curto E, Pediani JD, Milligan G. Applications of fluorescence and bioluminescence resonance energy transfer to drug discovery at G protein coupled receptors. Anal Bioanal Chem 2010; 398:167-80. [DOI: 10.1007/s00216-010-3823-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2010] [Revised: 05/03/2010] [Accepted: 05/03/2010] [Indexed: 10/19/2022]
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46
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Pisterzi LF, Jansma DB, Georgiou J, Woodside MJ, Chou JTC, Angers S, Raicu V, Wells JW. Oligomeric size of the m2 muscarinic receptor in live cells as determined by quantitative fluorescence resonance energy transfer. J Biol Chem 2010; 285:16723-38. [PMID: 20304928 PMCID: PMC2878013 DOI: 10.1074/jbc.m109.069443] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Revised: 03/07/2010] [Indexed: 11/06/2022] Open
Abstract
Fluorescence resonance energy transfer (FRET), measured by fluorescence intensity-based microscopy and fluorescence lifetime imaging, has been used to estimate the size of oligomers formed by the M(2) muscarinic cholinergic receptor. The approach is based on the relationship between the apparent FRET efficiency within an oligomer of specified size (n) and the pairwise FRET efficiency between a single donor and a single acceptor (E). The M(2) receptor was fused at the N terminus to enhanced green or yellow fluorescent protein and expressed in Chinese hamster ovary cells. Emission spectra were analyzed by spectral deconvolution, and apparent efficiencies were estimated by donor-dequenching and acceptor-sensitized emission at different ratios of enhanced yellow fluorescent protein-M(2) receptor to enhanced green fluorescent protein-M(2) receptor. The data were interpreted in terms of a model that considers all combinations of donor and acceptor within a specified oligomer to obtain fitted values of E as follows: n = 2, 0.495 +/- 0.019; n = 4, 0.202 +/- 0.010; n = 6, 0.128 +/- 0.006; n = 8, 0.093 +/- 0.005. The pairwise FRET efficiency determined independently by fluorescence lifetime imaging was 0.20-0.24, identifying the M(2) receptor as a tetramer. The strategy described here yields an explicit estimate of oligomeric size on the basis of fluorescence properties alone. Its broader application could resolve the general question of whether G protein-coupled receptors exist as dimers or larger oligomers. The size of an oligomer has functional implications, and such information can be expected to contribute to an understanding of the signaling process.
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Affiliation(s)
- Luca F. Pisterzi
- From The Leslie L. Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario M5S 3M2, Canada
| | - David B. Jansma
- the Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario M5S 3E1, Canada
| | - John Georgiou
- The Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
| | - Michael J. Woodside
- the Imaging Facility, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada, and
| | - Judy Tai-Chieh Chou
- From The Leslie L. Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario M5S 3M2, Canada
| | - Stéphane Angers
- From The Leslie L. Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario M5S 3M2, Canada
| | - Valerică Raicu
- the Departments of Physics and Biological Sciences, University of Wisconsin, Milwaukee, Wisconsin 53211
| | - James W. Wells
- From The Leslie L. Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario M5S 3M2, Canada
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47
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Alvarez-Curto E, Ward RJ, Pediani JD, Milligan G. Ligand regulation of the quaternary organization of cell surface M3 muscarinic acetylcholine receptors analyzed by fluorescence resonance energy transfer (FRET) imaging and homogeneous time-resolved FRET. J Biol Chem 2010; 285:23318-30. [PMID: 20489201 DOI: 10.1074/jbc.m110.122184] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Flp-In(TM) T-REx(TM) 293 cells expressing a wild type human M(3) muscarinic acetylcholine receptor construct constitutively and able to express a receptor activated solely by synthetic ligand (RASSL) form of this receptor on demand maintained response to the muscarinic agonist carbachol but developed response to clozapine N-oxide only upon induction of the RASSL. The two constructs co-localized at the plasma membrane and generated strong ratiometric fluorescence resonance energy transfer (FRET) signals consistent with direct physical interactions. Increasing levels of induction of the FRET donor RASSL did not alter wild type receptor FRET-acceptor levels substantially. However, ratiometric FRET was modulated in a bell-shaped fashion with maximal levels of the donor resulting in decreased FRET. Carbachol, but not the antagonist atropine, significantly reduced the FRET signal. Cell surface homogeneous time-resolved FRET, based on SNAP-tag technology and employing wild type and RASSL forms of the human M(3) receptor expressed stably in Flp-In(TM) TREx(TM) 293 cells, also identified cell surface dimeric/oligomeric complexes. Now, however, signals were enhanced by appropriate selective agonists. At the wild type receptor, large increases in FRET signal to carbachol and acetylcholine were concentration-dependent with EC(50) values consistent with the relative affinities of the two ligands. These studies confirm the capacity of the human M(3) muscarinic acetylcholine receptor to exist as dimeric/oligomeric complexes at the surface of cells and demonstrate that the organization of such complexes can be modified by ligand binding. However, conclusions as to the effect of ligands on such complexes may depend on the approach used.
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Affiliation(s)
- Elisa Alvarez-Curto
- Molecular Pharmacology Group, Neuroscience and Molecular Pharmacology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
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48
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Hern JA, Baig AH, Mashanov GI, Birdsall B, Corrie JET, Lazareno S, Molloy JE, Birdsall NJM. Formation and dissociation of M1 muscarinic receptor dimers seen by total internal reflection fluorescence imaging of single molecules. Proc Natl Acad Sci U S A 2010; 107:2693-8. [PMID: 20133736 PMCID: PMC2823895 DOI: 10.1073/pnas.0907915107] [Citation(s) in RCA: 303] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
G-protein-coupled receptors (GPCRs) are the largest family of transmembrane signaling proteins in the human genome. Events in the GPCR signaling cascade have been well characterized, but the receptor composition and its membrane distribution are still generally unknown. Although there is evidence that some members of the GPCR superfamily exist as constitutive dimers or higher oligomers, interpretation of the results has been disputed, and recent studies indicate that monomeric GPCRs may also be functional. Because there is controversy within the field, to address the issue we have used total internal reflection fluorescence microscopy (TIRFM) in living cells to visualize thousands of individual molecules of a model GPCR, the M(1) muscarinic acetylcholine receptor. By tracking the position of individual receptors over time, their mobility, clustering, and dimerization kinetics could be directly determined with a resolution of approximately 30 ms and approximately 20 nm. In isolated CHO cells, receptors are randomly distributed over the plasma membrane. At any given time, approximately 30% of the receptor molecules exist as dimers, and we found no evidence for higher oligomers. Two-color TIRFM established the dynamic nature of dimer formation with M(1) receptors undergoing interconversion between monomers and dimers on the timescale of seconds.
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Affiliation(s)
- Jonathan A. Hern
- Division of Physical Biochemistry, Medical Research Council National Institute for Medical Research, London NW7 1AA, United Kingdom; and
| | - Asma H. Baig
- Division of Physical Biochemistry, Medical Research Council National Institute for Medical Research, London NW7 1AA, United Kingdom; and
- Medical Research Council Technology, London NW7 1AD, United Kingdom
| | - Gregory I. Mashanov
- Division of Physical Biochemistry, Medical Research Council National Institute for Medical Research, London NW7 1AA, United Kingdom; and
| | - Berry Birdsall
- Division of Physical Biochemistry, Medical Research Council National Institute for Medical Research, London NW7 1AA, United Kingdom; and
| | - John E. T. Corrie
- Division of Physical Biochemistry, Medical Research Council National Institute for Medical Research, London NW7 1AA, United Kingdom; and
| | | | - Justin E. Molloy
- Division of Physical Biochemistry, Medical Research Council National Institute for Medical Research, London NW7 1AA, United Kingdom; and
| | - Nigel J. M. Birdsall
- Division of Physical Biochemistry, Medical Research Council National Institute for Medical Research, London NW7 1AA, United Kingdom; and
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49
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Direct interaction of GABAB receptors with M2 muscarinic receptors enhances muscarinic signaling. J Neurosci 2010; 29:15796-809. [PMID: 20016095 DOI: 10.1523/jneurosci.4103-09.2009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Downregulation of G-protein-coupled receptors (GPCRs) provides an important mechanism for reducing neurotransmitter signaling during sustained stimulation. Chronic stimulation of M(2) muscarinic receptors (M(2)Rs) causes internalization of M(2)R and G-protein-activated inwardly rectifying potassium (GIRK) channels in neuronal PC12 cells, resulting in loss of function. Here, we show that coexpression of GABA(B) R2 receptors (GBR2s) rescues both surface expression and function of M(2)R, including M(2)R-induced activation of GIRKs and inhibition of cAMP production. GBR2 showed significant association with M(2)R at the plasma membrane but not other GPCRs (M(1)R, mu-opioid receptor), as detected by fluorescence resonance energy transfer measured with total internal reflection fluorescence microscopy. Unique regions of the proximal C-terminal domains of GBR2 and M(2)R mediate specific binding between M(2)R and GBR2. In the brain, GBR2, but not GBR1, biochemically coprecipitates with M(2)R and overlaps with M(2)R expression in cortical neurons. This novel heteromeric association between M(2)R and GBR2 provides a possible mechanism for altering muscarinic signaling in the brain and represents a previously unrecognized role for GBR2.
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50
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M1 receptors mediate cholinergic modulation of excitability in neocortical pyramidal neurons. J Neurosci 2009; 29:9888-902. [PMID: 19657040 DOI: 10.1523/jneurosci.1366-09.2009] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
ACh release into the rodent prefrontal cortex is predictive of successful performance of cue detection tasks, yet the cellular mechanisms underlying cholinergic modulation of cortical function are not fully understood. Prolonged ("tonic") muscarinic ACh receptor (mAChR) activation increases the excitability of cortical pyramidal neurons, whereas transient ("phasic") mAChR activation generates inhibitory and/or excitatory responses, depending on neuron subtype. These cholinergic effects result from activation of "M1-like" mAChRs (M1, M3, and M5 receptors), but the specific receptor subtypes involved are not known. We recorded from cortical pyramidal neurons from wild-type mice and mice lacking M1, M3, and/or M5 receptors to determine the relative contribution of M1-like mAChRs to cholinergic signaling in the mouse prefrontal cortex. Wild-type neurons in layer 5 were excited by tonic mAChR stimulation, and had biphasic inhibitory followed by excitatory, responses to phasic ACh application. Pyramidal neurons in layer 2/3 were substantially less responsive to tonic and phasic cholinergic input. Cholinergic effects were largely absent in neurons from mice lacking M1 receptors, but most were robust in neurons lacking M3, M5, or both M3 and M5 receptors. The exception was tonic cholinergic suppression of the afterhyperpolarization in layer 5 neurons, which was absent in cells lacking either M1 or M3 receptors. Finally, we confirm a role for M1 receptors in behavior by demonstrating cue detection deficits in M1-lacking mice. Together, our results demonstrate that M1 receptors facilitate cue detection behaviors and are both necessary and sufficient for most direct effects of ACh on pyramidal neuron excitability.
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