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Hazan S, Tauber M, Ben Chaim Y. Voltage dependence of M2 muscarinic receptor antagonists and allosteric modulators. Biochem Pharmacol 2024:116421. [PMID: 38996933 DOI: 10.1016/j.bcp.2024.116421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 06/12/2024] [Accepted: 07/09/2024] [Indexed: 07/14/2024]
Abstract
Muscarinic receptors are G protein-coupled receptors (GPCRs) that play a role in various physiological functions. Previous studies have shown that these receptors, along with other GPCRs, are voltage-sensitive; both their affinity toward agonists and their activation are regulated by membrane potential. To our knowledge, whether the effect of antagonists on these receptors is voltage-dependent has not yet been studied. In this study, we used Xenopus oocytes expressing the M2 muscarinic receptor (M2R) to investigate this question. Our results indicate that the potencies of two M2R antagonists, atropine and scopolamine, are voltage-dependent; they are more effective at resting potential than under depolarization. In contrast, the M2R antagonist AF-DX 386 did not exhibit voltage-dependent potency.Furthermore, we discovered that the voltage dependence of M2R activation by acetylcholine remains unchanged in the presence of two allosteric modulators, the negative modulator gallamine and the positive modulator LY2119620. These findings enhance our understanding of GPCRs' voltage dependence and may have pharmacological implications.
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Affiliation(s)
- Shimrit Hazan
- Department of Natural Sciences, The Open University of Israel, Ra'anana, Israel
| | - Merav Tauber
- Department of Natural Sciences, The Open University of Israel, Ra'anana, Israel
| | - Yair Ben Chaim
- Department of Natural Sciences, The Open University of Israel, Ra'anana, Israel.
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2
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Tauber M, Ben-Chaim Y. Voltage Sensors Embedded in G Protein-Coupled Receptors. Int J Mol Sci 2024; 25:5295. [PMID: 38791333 PMCID: PMC11120775 DOI: 10.3390/ijms25105295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Revised: 05/08/2024] [Accepted: 05/09/2024] [Indexed: 05/26/2024] Open
Abstract
Some signaling processes mediated by G protein-coupled receptors (GPCRs) are modulated by membrane potential. In recent years, increasing evidence that GPCRs are intrinsically voltage-dependent has accumulated. A recent publication challenged the view that voltage sensors are embedded in muscarinic receptors. Herein, we briefly discuss the evidence that supports the notion that GPCRs themselves are voltage-sensitive proteins and an alternative mechanism that suggests that voltage-gated sodium channels are the voltage-sensing molecules involved in such processes.
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Affiliation(s)
| | - Yair Ben-Chaim
- Department of Natural Sciences, The Open University of Israel, Ra’anana 4353701, Israel
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3
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Rahman SN, Imhaouran F, Leurs R, Christopoulos A, Valant C, Langmead CJ. Ligand-directed biased agonism at human histamine H 3 receptor isoforms across Gα i/o- and β-arrestin2-mediated pathways. Biochem Pharmacol 2023:115988. [PMID: 38159685 DOI: 10.1016/j.bcp.2023.115988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 12/13/2023] [Accepted: 12/15/2023] [Indexed: 01/03/2024]
Abstract
The histamine H3 receptor (H3R) is a neurotransmitter receptor that is primarily found in the brain, where it controls the release and synthesis of histamine, as well as the release of other neurotransmitters (e.g. dopamine, serotonin). Notably, 20 H3R isoforms are differentially expressed in the human brain as a consequence of alternative gene splicing. The hH3R-445, -415, -365 and -329 isoforms contain the prototypical GPCR (7TM) structure, yet exhibit deletions in the third intracellular loop, a structural domain that is pivotal for G protein-coupling, signaling and regulation. To date, the physiological relevance underlying the individual and combinatorial function of hH3R isoforms remains poorly understood. Nevertheless, given their significant implication in physiological processes (e.g. cognition, homeostasis) and neurological disorders (e.g. Alzheimer's and Parkinson's disease, schizophrenia), widespread targeting of hH3R isoforms by drugs may lead to on-target side effects in brain regions that are unaffected by disease. To this end, isoform- and/or pathway-selective targeting of hH3R isoforms by biased agonists could be of therapeutic relevance for the development of region- and disease-specific drugs. Hence, we have evaluated ligand biased signaling at the hH3R-445, -415, -365 and -329 isoforms across various Gαi/o-mediated (i.e. [35S]GTPγS accumulation, cAMP inhibition, pERK1/2 activation, pAKT T308/S473 activation) and non Gαi/o-mediated (i.e. β-arrestin2 recruitment) endpoints that are relevant to neurological diseases. Our findings indicate that H3R agonists display significantly altered patterns in their degree of ligand bias, in a pathway- and isoform-dependent manner, underlining the significance to investigate GPCRs with multiple isoforms to improve development of selective drugs. SUBJECT CATEGORY: Neuropharmacology.
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Affiliation(s)
- Sabrina N Rahman
- Drug Discovery Biology and Neuromedicines Discovery Centre, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, 3052 VIC, Parkville, Melbourne, Australia; Amsterdam Institute for Molecular Life Sciences, Division of Medicinal Chemistry, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands.
| | - Faissal Imhaouran
- Amsterdam Institute for Molecular Life Sciences, Division of Medicinal Chemistry, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
| | - Rob Leurs
- Amsterdam Institute for Molecular Life Sciences, Division of Medicinal Chemistry, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
| | - Arthur Christopoulos
- Drug Discovery Biology and Neuromedicines Discovery Centre, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, 3052 VIC, Parkville, Melbourne, Australia
| | - Céline Valant
- Drug Discovery Biology and Neuromedicines Discovery Centre, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, 3052 VIC, Parkville, Melbourne, Australia.
| | - Christopher J Langmead
- Drug Discovery Biology and Neuromedicines Discovery Centre, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, 3052 VIC, Parkville, Melbourne, Australia.
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4
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Seldeslachts A, Peigneur S, Tytgat J. Histamine Receptors: Ex Vivo Functional Studies Enabling the Discovery of Hits and Pathways. MEMBRANES 2023; 13:897. [PMID: 38132901 PMCID: PMC10744718 DOI: 10.3390/membranes13120897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 11/23/2023] [Accepted: 11/24/2023] [Indexed: 12/23/2023]
Abstract
Histamine receptors (HRs) are G-protein-coupled receptors involved in diverse responses triggered by histamine release during inflammation or by encounters with venomous creatures. Four histamine receptors (H1R-H4R) have been cloned and extensively characterized. These receptors are distributed throughout the body and their activation is associated with clinical manifestations such as urticaria (H1R), gastric acid stimulation (H2R), regulation of neurotransmitters in neuronal diseases (H3R), and immune responses (H4R). Despite significant homologous overlap between H3R and H4R, much remains unknown about their precise roles. Even though some drugs have been developed for H1R, H2R, and H3R, not a single H4R antagonist has been approved for clinical use. To enhance our understanding and advance innovative therapeutic targeting of H1R, H2R, H3R, and H4R, we established a robust ex vivo functional platform. This platform features the successful heterologous expression of H1R-H4R in Xenopus laevis oocytes, utilizing an electrophysiological readout. Our findings contribute to a deeper understanding of the function and pharmacological properties of the histamine receptors. Researchers can benefit from the utility of this platform when investigating the effects of histamine receptors and exploring potential therapeutic targets. In doing so, it broadens the horizon of drug discovery, offering new perspectives for therapeutic interventions.
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Affiliation(s)
| | - Steve Peigneur
- Toxicology and Pharmacology, KU Leuven, Campus Gasthuisberg, O&N2, Herestraat 49, P.O. Box 922, 3000 Leuven, Belgium;
| | - Jan Tytgat
- Toxicology and Pharmacology, KU Leuven, Campus Gasthuisberg, O&N2, Herestraat 49, P.O. Box 922, 3000 Leuven, Belgium;
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5
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Buzoianu AD, Sharma A, Muresanu DF, Feng L, Huang H, Chen L, Tian ZR, Nozari A, Lafuente JV, Wiklund L, Sharma HS. Nanodelivery of Histamine H3/H4 Receptor Modulators BF-2649 and Clobenpropit with Antibodies to Amyloid Beta Peptide in Combination with Alpha Synuclein Reduces Brain Pathology in Parkinson's Disease. ADVANCES IN NEUROBIOLOGY 2023; 32:55-96. [PMID: 37480459 DOI: 10.1007/978-3-031-32997-5_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/24/2023]
Abstract
Parkinson's disease (PD) in military personnel engaged in combat operations is likely to develop in their later lives. In order to enhance the quality of lives of PD patients, exploration of novel therapy based on new research strategies is highly warranted. The hallmarks of PD include increased alpha synuclein (ASNC) and phosphorylated tau (p-tau) in the cerebrospinal fluid (CSF) leading to brain pathology. In addition, there are evidences showing increased histaminergic nerve fibers in substantia niagra pars compacta (SNpc), striatum (STr), and caudate putamen (CP) associated with upregulation of histamine H3 receptors and downregulation of H4 receptors in human brain. Previous studies from our group showed that modulation of potent histaminergic H3 receptor inverse agonist BF-2549 or clobenpropit (CLBPT) partial histamine H4 agonist with H3 receptor antagonist induces neuroprotection in PD brain pathology. Recent studies show that PD also enhances amyloid beta peptide (AβP) depositions in brain. Keeping these views in consideration in this review, nanowired delivery of monoclonal antibodies to AβP together with ASNC and H3/H4 modulator drugs on PD brain pathology is discussed based on our own observations. Our investigation shows that TiO2 nanowired BF-2649 (1 mg/kg, i.p.) or CLBPT (1 mg/kg, i.p.) once daily for 1 week together with nanowired delivery of monoclonal antibodies (mAb) to AβP and ASNC induced superior neuroprotection in PD-induced brain pathology. These observations are the first to show the modulation of histaminergic receptors together with antibodies to AβP and ASNC induces superior neuroprotection in PD. These observations open new avenues for the development of novel drug therapies for clinical strategies in PD.
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Affiliation(s)
- Anca D Buzoianu
- Department of Clinical Pharmacology and Toxicology, "Iuliu Hatieganu" University of Medicine and Pharmacy, Cluj-Napoca, Romania
| | - Aruna Sharma
- International Experimental Central Nervous System Injury & Repair (IECNSIR), Department of Surgical Sciences, Anesthesiology & Intensive Care Medicine, Uppsala University Hospital, Uppsala University, Uppsala, Sweden
| | - Dafin F Muresanu
- Department of Clinical Neurosciences, University of Medicine & Pharmacy, Cluj-Napoca, Romania
- "RoNeuro" Institute for Neurological Research and Diagnostic, Cluj-Napoca, Romania
| | - Lianyuan Feng
- Department of Neurology, Bethune International Peace Hospital, Zhongshan, Hebei Province, China
| | - Hongyun Huang
- Beijing Hongtianji Neuroscience Academy, Beijing, China
| | - Lin Chen
- Department of Neurosurgery, Dongzhimen Hospital, Beijing University of Traditional Chinese Medicine, Beijing, China
| | - Z Ryan Tian
- Department of Chemistry & Biochemistry, University of Arkansas, Fayetteville, AR, USA
| | - Ala Nozari
- Anesthesiology & Intensive Care, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA, USA
| | - José Vicente Lafuente
- LaNCE, Department of Neuroscience, University of the Basque Country (UPV/EHU), Leioa, Bizkaia, Spain
| | - Lars Wiklund
- International Experimental Central Nervous System Injury & Repair (IECNSIR), Department of Surgical Sciences, Anesthesiology & Intensive Care Medicine, Uppsala University Hospital, Uppsala University, Uppsala, Sweden
| | - Hari Shanker Sharma
- International Experimental Central Nervous System Injury & Repair (IECNSIR), Department of Surgical Sciences, Anesthesiology & Intensive Care Medicine, Uppsala University Hospital, Uppsala University, Uppsala, Sweden.
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Sergeeva OA, Mazur K, Reiner-Link D, Lutsenko K, Haas HL, Alfonso-Prieto M, Stark H. OLHA (N α-oleoylhistamine) modulates activity of mouse brain histaminergic neurons. Neuropharmacology 2022; 215:109167. [PMID: 35750238 DOI: 10.1016/j.neuropharm.2022.109167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 06/01/2022] [Accepted: 06/13/2022] [Indexed: 11/26/2022]
Abstract
Histaminergic (HA) neurons are located in the tuberomamillary nucleus (TMN) of the posterior hypothalamus, from where they project throughout the whole brain to control wakefulness. We examined the effects of Nα-oleoylhistamine (OLHA), a non-enzymatic condensation product of oleic acid (OLA) and histamine, on activity of mouse HA neurons in brain slices. OLHA bidirectionally modulated the firing of HA neurons. At 10 nM OLHA inhibited or had no action, whereas at 1 μM it evoked excitatory and inhibitory responses. Inhibition was not seen in presence of the histamine receptor H3 (H3R) antagonist clobenpropit and in calcium-free medium. Pre-incubation with a histamine-reuptake blocker prevented the decrease in firing by OLHA. OLHA-evoked increase in firing (EC50 ∼44 nM) was insensitive to blockers of cannabinoid 1 and 2 receptors and of the capsaicin receptor, but was significantly impaired by the peroxisome proliferator-activated receptor-alpha (PPAR-alpha) antagonist MK886, which suppressed also the rise in intracellular calcium level caused by OLHA. The OLHA-evoked excitation was mimicked by synthetic PPAR-alpha agonists (gemfibrozil and GW7647) and was abolished by the PKA inhibitor H-89. The H3R affinity (Ki) for histamine, measured in HEK293 cells with stable expression of human H3R, was higher than for OLHA (Ki: 42 vs 310 nM, respectively). Expression of PPAR-alpha was not different between TMN regions of males and females, responses to OLHA did not differ. Molecular modelling of PPAR-alpha bound to either OLHA or OEA showed similar binding energies. These findings shed light on a novel biotransformation product of histamine which may play a role in health and disease.
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Affiliation(s)
- Olga A Sergeeva
- Institute of Neural and Sensory Physiology, Medical Faculty, Heinrich Heine University Düsseldorf, 40225, Düsseldorf, Germany; Institute of Clinical Neurosciences and Medical Psychology, Medical Faculty, Heinrich Heine University Düsseldorf, 40225, Düsseldorf, Germany.
| | - Karolina Mazur
- Institute of Clinical Neurosciences and Medical Psychology, Medical Faculty, Heinrich Heine University Düsseldorf, 40225, Düsseldorf, Germany
| | - David Reiner-Link
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, 40225, Düsseldorf, Germany
| | - Kiril Lutsenko
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, 40225, Düsseldorf, Germany
| | - Helmut L Haas
- Institute of Neural and Sensory Physiology, Medical Faculty, Heinrich Heine University Düsseldorf, 40225, Düsseldorf, Germany
| | - Mercedes Alfonso-Prieto
- Cécile and Oskar Vogt Institute for Brain Research, Medical Faculty, Heinrich Heine University Düsseldorf, 40225, Düsseldorf, Germany; Computational Biomedicine, Institute for Advanced Simulation IAS-5/Institute for Neuroscience and Medicine INM-9, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - Holger Stark
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, 40225, Düsseldorf, Germany
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López-Serrano AL, Zamora-Cárdenas R, Aréchiga-Figueroa IA, Salazar-Fajardo PD, Ferrer T, Alamilla J, Sánchez-Chapula JA, Navarro-Polanco RA, Moreno-Galindo EG. Differential voltage-dependent modulation of the ACh-gated K+ current by adenosine and acetylcholine. PLoS One 2022; 17:e0261960. [PMID: 35030226 PMCID: PMC8759768 DOI: 10.1371/journal.pone.0261960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 12/14/2021] [Indexed: 11/18/2022] Open
Abstract
Inhibitory regulation of the heart is determined by both cholinergic M2 receptors (M2R) and adenosine A1 receptors (A1R) that activate the same signaling pathway, the ACh-gated inward rectifier K+ (KACh) channels via Gi/o proteins. Previously, we have shown that the agonist-specific voltage sensitivity of M2R underlies several voltage-dependent features of IKACh, including the ‘relaxation’ property, which is characterized by a gradual increase or decrease of the current when cardiomyocytes are stepped to hyperpolarized or depolarized voltages, respectively. However, it is unknown whether membrane potential also affects A1R and how this could impact IKACh. Upon recording whole-cell currents of guinea-pig cardiomyocytes, we found that stimulation of the A1R-Gi/o-IKACh pathway with adenosine only caused a very slight voltage dependence in concentration-response relationships (~1.2-fold EC50 increase with depolarization) that was not manifested in the relative affinity, as estimated by the current deactivation kinetics (τ = 4074 ± 214 ms at -100 mV and τ = 4331 ± 341 ms at +30 mV; P = 0.31). Moreover, IKACh did not exhibit relaxation. Contrarily, activation of the M2R-Gi/o-IKACh pathway with acetylcholine induced the typical relaxation of the current, which correlated with the clear voltage-dependent effect observed in the concentration-response curves (~2.8-fold EC50 increase with depolarization) and in the IKACh deactivation kinetics (τ = 1762 ± 119 ms at -100 mV and τ = 1503 ± 160 ms at +30 mV; P = 0.01). Our findings further substantiate the hypothesis of the agonist-specific voltage dependence of GPCRs and that the IKACh relaxation is consequence of this property.
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Affiliation(s)
- Ana Laura López-Serrano
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Col., Mexico
| | - Rodrigo Zamora-Cárdenas
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Col., Mexico
| | - Iván A. Aréchiga-Figueroa
- CONACYT, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, S.L.P., Mexico
| | | | - Tania Ferrer
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Col., Mexico
| | - Javier Alamilla
- CONACYT, Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Col., Mexico
| | - José A. Sánchez-Chapula
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Col., Mexico
| | | | - Eloy G. Moreno-Galindo
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Col., Mexico
- * E-mail:
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8
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Ågren R, Sahlholm K. Voltage-Dependent Dopamine Potency at D 1-Like Dopamine Receptors. Front Pharmacol 2020; 11:581151. [PMID: 33117177 PMCID: PMC7577048 DOI: 10.3389/fphar.2020.581151] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 09/16/2020] [Indexed: 01/17/2023] Open
Abstract
In recent years, transmembrane voltage has been found to modify agonist potencies at several G protein-coupled receptors (GPCRs). Whereas the voltage sensitivities of the Gαi/o-coupled dopamine D2-like receptors (D2R, D3R, D4R) have previously been investigated, the putative impact of transmembrane voltage on agonist potency at the mainly Gαs/olf-coupled dopamine D1-like receptors (D1R, D5R) has hitherto not been reported. Here, we assayed the potency of dopamine in activating G protein-coupled inward rectifier potassium (GIRK) channels co-expressed with D1R and D5R in Xenopus oocytes, at -80 mV and at 0 mV. Furthermore, GIRK response deactivation rates upon dopamine washout were measured to estimate dopamine dissociation rate (koff) constants. Depolarization from -80 to 0 mV was found to reduce dopamine potency by about 7-fold at both D1R and D5R. This potency reduction was accompanied by an increase in estimated dopamine koffs at both receptors. While the GIRK response elicited via D1R was insensitive to pertussis toxin (PTX), the response evoked via D5R was reduced by 64% (-80 mV) and 71% (0 mV) in the presence of PTX. Injection of oocytes with Gαs antisense oligonucleotide inhibited the D1R-mediated response by 62% (-80 mV) and 76% (0 mV) and abolished the D5R response when combined with PTX. Our results suggest that depolarization decreases dopamine affinity at D1R and D5R. The voltage-dependent affinities of dopamine at D1R and D5R may be relevant to the functions of these receptors in learning and memory.
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Affiliation(s)
- Richard Ågren
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Kristoffer Sahlholm
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.,Department of Integrative Medical Biology, Umeå University, Umeå, Sweden.,Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden
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9
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Ruland JG, Kirchhofer SB, Klindert S, Bailey CP, Bünemann M. Voltage modulates the effect of μ-receptor activation in a ligand-dependent manner. Br J Pharmacol 2020; 177:3489-3504. [PMID: 32297669 PMCID: PMC7348086 DOI: 10.1111/bph.15070] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 03/16/2020] [Accepted: 03/30/2020] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND AND PURPOSE Various GPCRs have been described as being modulated in a voltage-dependent manner. Opioid analgesics act via activation of μ receptors in various neurons. As neurons are exposed to large changes in membrane potential, we were interested in studying the effects of depolarization on μ receptor signalling. EXPERIMENTAL APPROACH We investigated potential voltage sensitivity of μ receptors in heterologous expression systems (HEK293T cells) using electrophysiology in combination with Förster resonance energy transfer-based assays. Depolarization-induced changes in signalling were also tested in physiological rat tissue containing locus coeruleus neurons. We applied depolarization steps across the physiological range of membrane potentials. KEY RESULTS Studying μ receptor function and signalling in cells, we discovered that morphine-induced signalling was strongly dependent on the membrane potential (VM ). This became apparent at the level of G-protein activation, G-protein coupled inwardly rectifying potassium channel (Kir 3.X) currents and binding of GPCR kinases and arrestin3 to μ receptors by a robust increase in signalling upon membrane depolarization. The pronounced voltage sensitivity of morphine-induced μ receptor activation was also observed at the level of Kir 3.X currents in rat locus coeruleus neurons. The efficacy of peptide ligands to activate μ receptors was not (Met-enkephalin) or only moderately ([D-Ala2 , N-Me-Phe4 , Gly5 -ol]-enkephalin) enhanced upon depolarization. In contrast, depolarization reduced the ability of the analgesic fentanyl to activate μ receptors. CONCLUSION AND IMPLICATIONS Our results indicate a strong ligand-dependent modulation of μ receptor activity by the membrane potential, suggesting preferential activity of morphine in neurons with high neuronal activity.
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Affiliation(s)
- Julia G Ruland
- Department of Pharmacology and Clinical Pharmacy, Philipps-University, Marburg, Germany
| | - Sina B Kirchhofer
- Department of Pharmacology and Clinical Pharmacy, Philipps-University, Marburg, Germany
| | - Sebastian Klindert
- Department of Pharmacology and Clinical Pharmacy, Philipps-University, Marburg, Germany.,Department of Pharmacy and Pharmacology, University of Bath, Bath, UK
| | - Chris P Bailey
- Department of Pharmacy and Pharmacology, University of Bath, Bath, UK
| | - Moritz Bünemann
- Department of Pharmacology and Clinical Pharmacy, Philipps-University, Marburg, Germany
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10
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López-Serrano AL, De Jesús-Pérez JJ, Zamora-Cárdenas R, Ferrer T, Rodríguez-Menchaca AA, Tristani-Firouzi M, Moreno-Galindo EG, Navarro-Polanco RA. Voltage-induced structural modifications on M2 muscarinic receptor and their functional implications when interacting with the superagonist iperoxo. Biochem Pharmacol 2020; 177:113961. [PMID: 32272111 DOI: 10.1016/j.bcp.2020.113961] [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: 01/23/2020] [Accepted: 04/02/2020] [Indexed: 12/31/2022]
Abstract
It has been reported that muscarinic type-2 receptors (M2R) are voltage sensitive in an agonist-specific manner. In this work, we studied the effects of membrane potential on the interaction of M2R with the superagonist iperoxo (IXO), both functionally (using the activation of the ACh-gated K+ current (IKACh) in cardiomyocytes) and by molecular dynamics (MD) simulations. We found that IXO activated IKACh with remarkable high potency and clear voltage dependence, displaying a larger effect at the hyperpolarized potential. This result is consistent with a greater affinity, as validated by a slower (τ = 14.8 ± 2.3 s) deactivation kinetics of the IXO-evoked IKACh than that at the positive voltage (τ = 6.7 ± 1.2 s). The voltage-dependent M2R-IXO interaction induced IKACh to exhibit voltage-dependent features of this current, such as the 'relaxation gating' and the modulation of rectification. MD simulations revealed that membrane potential evoked specific conformational changes both at the external access and orthosteric site of M2R that underlie the agonist affinity change provoked by voltage on M2R. Moreover, our experimental data suggest that the 'tyrosine lid' (Y104, Y403, and Y426) is not the previously proposed voltage sensor of M2R. These findings provide an insight into the structural and functional framework of the biased signaling induced by voltage on GPCRs.
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Affiliation(s)
- Ana Laura López-Serrano
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Col., Mexico
| | - José J De Jesús-Pérez
- Instituto de Física, Universidad Autónoma de San Luis Potosí, San Luis Potosí, SLP, Mexico; Department of Physiology and Biophysics, University of Washington, Seattle, WA, USA
| | - Rodrigo Zamora-Cárdenas
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Col., Mexico
| | - Tania Ferrer
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Col., Mexico
| | - Aldo A Rodríguez-Menchaca
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, SLP, Mexico
| | - Martin Tristani-Firouzi
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA; Division of Pediatric Cardiology, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Eloy G Moreno-Galindo
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Col., Mexico.
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11
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Heblinski M, Bladen C, Connor M. Regulation of heterologously expressed 5-HT 1B receptors coupling to potassium channels in AtT-20 cells. Br J Pharmacol 2018; 176:451-465. [PMID: 30447001 DOI: 10.1111/bph.14547] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 10/08/2018] [Accepted: 10/17/2018] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND AND PURPOSE 5-HT1B receptors are widely expressed GPCRs and a target of triptans, the most commonly prescribed anti-migraine drugs. There is very limited information about the acute, agonist-induced regulation of 5-HT1B receptor signalling and so we sought to characterize this in a neuron-like system. EXPERIMENTAL APPROACH Epitope-tagged human 5-HT1B receptors were expressed in mouse AtT20 cells. 5-HT1B receptor signalling was assessed using whole-cell patch-clamp recordings of endogenous G protein-gated inwardly rectified potassium (GIRK) channels, and receptor localization measured using immunofluorescence. KEY RESULTS 5-HT (EC50 65 nM) and sumatriptan (EC50 165 nM) activated GIRK channels in AtT20 cells expressing 5-HT1B receptors. Continuous application of both 5-HT (EC50 120 nM) and sumatriptan (EC50 280 nM) produced profound desensitization of 5-HT1B receptor signalling within a few minutes. Complete recovery from desensitization was observed after 10 min. Both 5-HT and sumatriptan induced significant heterologous desensitization of SRIF (somatostatin)-activated GIRK currents, with the 5-HT-induced heterologous desensitization being blocked by the protein kinase inhibitor staurosporine. Both agonists induced modest 5-HT1B receptor internalization, with a time course much slower than receptor desensitization. CONCLUSIONS AND IMPLICATIONS In AtT-20 cells, 5-HT1B receptors undergo rapid and reversible desensitization at concentrations of agonist similar to those required to activate the receptor. Desensitization is incomplete, and the continued signalling of the receptor in the presence of the agonist may lead to cellular adaptations. Finally, 5-HT1B receptor activation causes significant heterologous desensitization, which may lead to a reduced effectiveness of unrelated drugs in vivo.
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Affiliation(s)
- Marika Heblinski
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Christopher Bladen
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Mark Connor
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
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12
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Nieto-Alamilla G, Escamilla-Sánchez J, López-Méndez MC, Molina-Hernández A, Guerrero-Hernández A, Arias-Montaño JA. Differential expression and signaling of the human histamine H 3 receptor isoforms of 445 and 365 amino acids expressed in human neuroblastoma SH-SY5Y cells. J Recept Signal Transduct Res 2018; 38:141-150. [PMID: 29557708 DOI: 10.1080/10799893.2018.1448995] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
In stably-transfected human neuroblastoma SH-SY5Y cells, we have compared the effect of activating two isoforms of 445 and 365 amino acids of the human histamine H3 receptor (hH3R445 and hH3R365) on [35S]-GTPγS binding, forskolin-induced cAMP formation, depolarization-induced increase in the intracellular concentration of Ca2+ ions ([Ca2+]i) and depolarization-evoked [3 H]-dopamine release. Maximal specific binding (Bmax) of [3 H]-N-methyl-histamine to cell membranes was 953 ± 204 and 555 ± 140 fmol/mg protein for SH-SY5Y-hH3R445 and SH-SY5Y-hH3R365 cells, respectively, with similar dissociation constants (Kd, 0.86 nM and 0.81 nM). The mRNA of the hH3R365 isoform was 40.9 ± 7.9% of the hH3R445 isoform. No differences in receptor affinity were found for the H3R ligands histamine, immepip, (R)(-)-α-methylhistamine (RAMH), A-331440, clobenpropit and ciproxifan. Both the stimulation of [35S]-GTPγS binding and the inhibition of forskolin-stimulated cAMP accumulation by the agonist RAMH were significantly larger in SH-SY5Y-hH3R445 cells ([35S]-GTPγS binding, 158.1 ± 7.5% versus 136.5 ± 3.6% for SH-SY5Y-hH3R365 cells; cAMP accumulation, -74.0 ± 4.9% versus -43.5 ± 5.3%), with no significant effect on agonist potency. In contrast, there were no differences in the efficacy and potency of RAMH to inhibit [3 H]-dopamine release evoked by 100 mM K+ (-18.9 ± 3.0% and -20.5 ± 3.3%, for SH-SY5Y-hH3R445 and SH-SY5Y-hH3R365 cells), or the inhibition of depolarization-induced increase in [Ca2+]i (S2/S1 ratios: parental cells 0.967 ± 0.069, SH-SY5Y-hH3R445 cells 0.639 ± 0.049, SH-SY5Y-hH3R365 cells 0.737 ± 0.045). These results indicate that in SH-SY5Y cells, hH3R445 and hH3R365 isoforms regulate in a differential manner the signaling pathways triggered by receptor activation.
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Affiliation(s)
- Gustavo Nieto-Alamilla
- a Departamento de Fisiología, Biofísica y Neurociencias , Centro de Investigación y de Estudios Avanzados del IPN , Ciudad de México , México
| | - Juan Escamilla-Sánchez
- a Departamento de Fisiología, Biofísica y Neurociencias , Centro de Investigación y de Estudios Avanzados del IPN , Ciudad de México , México
| | - María-Cristina López-Méndez
- b Departamento de Bioquímica, Centro de Investigación y de Estudios Avanzados del IPN , Ciudad de México , México
| | - Anayansi Molina-Hernández
- c Departamento de Biología Celular , Instituto Nacional de Perinatología Isidro Espinosa de los Reyes , Ciudad de México , México
| | - Agustín Guerrero-Hernández
- b Departamento de Bioquímica, Centro de Investigación y de Estudios Avanzados del IPN , Ciudad de México , México
| | - José-Antonio Arias-Montaño
- a Departamento de Fisiología, Biofísica y Neurociencias , Centro de Investigación y de Estudios Avanzados del IPN , Ciudad de México , México
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13
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Point mutation of a conserved aspartate, D69, in the muscarinic M 2 receptor does not modify voltage-sensitive agonist potency. Biochem Biophys Res Commun 2018; 496:101-104. [DOI: 10.1016/j.bbrc.2018.01.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 01/01/2018] [Indexed: 12/30/2022]
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14
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Hu W, Chen Z. The roles of histamine and its receptor ligands in central nervous system disorders: An update. Pharmacol Ther 2017; 175:116-132. [DOI: 10.1016/j.pharmthera.2017.02.039] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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15
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Riddy DM, Cook AE, Diepenhorst NA, Bosnyak S, Brady R, Mannoury la Cour C, Mocaer E, Summers RJ, Charman WN, Sexton PM, Christopoulos A, Langmead CJ. Isoform-Specific Biased Agonism of Histamine H3 Receptor Agonists. Mol Pharmacol 2016; 91:87-99. [PMID: 27864425 DOI: 10.1124/mol.116.106153] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Accepted: 11/17/2016] [Indexed: 12/11/2022] Open
Abstract
The human histamine H3 receptor (hH3R) is subject to extensive gene splicing that gives rise to a large number of functional and nonfunctional isoforms. Despite the general acceptance that G protein-coupled receptors can adopt different ligand-induced conformations that give rise to biased signaling, this has not been studied for the H3R; further, it is unknown whether splice variants of the same receptor engender the same or differential biased signaling. Herein, we profiled the pharmacology of histamine receptor agonists at the two most abundant hH3R splice variants (hH3R445 and hH3R365) across seven signaling endpoints. Both isoforms engender biased signaling, notably for 4-[3-(benzyloxy)propyl]-1H-imidazole (proxyfan) [e.g., strong bias toward phosphorylation of glycogen synthase kinase 3β (GSK3β) via the full-length receptor] and its congener 3-(1H-imidazol-4-yl)propyl-(4-iodophenyl)-methyl ether (iodoproxyfan), which are strongly consistent with the former's designation as a "protean" agonist. The 80 amino acid IL3 deleted isoform hH3R365 is more permissive in its signaling than hH3R445: 2-(1H-imidazol-5-yl)ethyl imidothiocarbamate (imetit), proxyfan, and iodoproxyfan were all markedly biased away from calcium signaling, and principal component analysis of the full data set revealed divergent profiles for all five agonists. However, most interesting was the identification of differential biased signaling between the two isoforms. Strikingly, hH3R365 was completely unable to stimulate GSK3β phosphorylation, an endpoint robustly activated by the full-length receptor. To the best of our knowledge, this is the first quantitative example of differential biased signaling via isoforms of the same G protein-coupled receptor that are simultaneously expressed in vivo and gives rise to the possibility of selective pharmacological targeting of individual receptor splice variants.
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Affiliation(s)
- Darren M Riddy
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia (D.M.R., A.E.C., N.A.D., S.B., R.B., R.J.S., W.N.C., P.M.S., A.C., C.J.L.); and Institut de Recherches Internationales Servier, Suresnes, France (C.M.C., E.M.)
| | - Anna E Cook
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia (D.M.R., A.E.C., N.A.D., S.B., R.B., R.J.S., W.N.C., P.M.S., A.C., C.J.L.); and Institut de Recherches Internationales Servier, Suresnes, France (C.M.C., E.M.)
| | - Natalie A Diepenhorst
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia (D.M.R., A.E.C., N.A.D., S.B., R.B., R.J.S., W.N.C., P.M.S., A.C., C.J.L.); and Institut de Recherches Internationales Servier, Suresnes, France (C.M.C., E.M.)
| | - Sanja Bosnyak
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia (D.M.R., A.E.C., N.A.D., S.B., R.B., R.J.S., W.N.C., P.M.S., A.C., C.J.L.); and Institut de Recherches Internationales Servier, Suresnes, France (C.M.C., E.M.)
| | - Ryan Brady
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia (D.M.R., A.E.C., N.A.D., S.B., R.B., R.J.S., W.N.C., P.M.S., A.C., C.J.L.); and Institut de Recherches Internationales Servier, Suresnes, France (C.M.C., E.M.)
| | - Clotilde Mannoury la Cour
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia (D.M.R., A.E.C., N.A.D., S.B., R.B., R.J.S., W.N.C., P.M.S., A.C., C.J.L.); and Institut de Recherches Internationales Servier, Suresnes, France (C.M.C., E.M.)
| | - Elisabeth Mocaer
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia (D.M.R., A.E.C., N.A.D., S.B., R.B., R.J.S., W.N.C., P.M.S., A.C., C.J.L.); and Institut de Recherches Internationales Servier, Suresnes, France (C.M.C., E.M.)
| | - Roger J Summers
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia (D.M.R., A.E.C., N.A.D., S.B., R.B., R.J.S., W.N.C., P.M.S., A.C., C.J.L.); and Institut de Recherches Internationales Servier, Suresnes, France (C.M.C., E.M.)
| | - William N Charman
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia (D.M.R., A.E.C., N.A.D., S.B., R.B., R.J.S., W.N.C., P.M.S., A.C., C.J.L.); and Institut de Recherches Internationales Servier, Suresnes, France (C.M.C., E.M.)
| | - Patrick M Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia (D.M.R., A.E.C., N.A.D., S.B., R.B., R.J.S., W.N.C., P.M.S., A.C., C.J.L.); and Institut de Recherches Internationales Servier, Suresnes, France (C.M.C., E.M.)
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia (D.M.R., A.E.C., N.A.D., S.B., R.B., R.J.S., W.N.C., P.M.S., A.C., C.J.L.); and Institut de Recherches Internationales Servier, Suresnes, France (C.M.C., E.M.)
| | - Christopher J Langmead
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia (D.M.R., A.E.C., N.A.D., S.B., R.B., R.J.S., W.N.C., P.M.S., A.C., C.J.L.); and Institut de Recherches Internationales Servier, Suresnes, France (C.M.C., E.M.)
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16
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Zhang XC, Zhou Y, Cao C. Thermodynamics of GPCR activation. BIOPHYSICS REPORTS 2016; 1:115-119. [PMID: 27340689 PMCID: PMC4871901 DOI: 10.1007/s41048-016-0017-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 01/06/2016] [Indexed: 12/30/2022] Open
Affiliation(s)
- Xuejun C Zhang
- National Laboratory of Macromolecules, National Center of Protein Science-Beijing, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
| | - Ye Zhou
- National Laboratory of Macromolecules, National Center of Protein Science-Beijing, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
| | - Can Cao
- National Laboratory of Macromolecules, National Center of Protein Science-Beijing, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
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17
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Rinne A, Mobarec JC, Mahaut-Smith M, Kolb P, Bünemann M. The mode of agonist binding to a G protein-coupled receptor switches the effect that voltage changes have on signaling. Sci Signal 2015; 8:ra110. [PMID: 26535008 DOI: 10.1126/scisignal.aac7419] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Signaling by many heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) is either enhanced or attenuated by changes in plasma membrane potential. To identify structural correlates of the voltage sensitivity of GPCR signaling, we chose muscarinic acetylcholine receptors (the M1, M3, and M5 isoforms) as a model system. We combined molecular docking analysis with Förster resonance energy transfer (FRET)-based assays that monitored receptor activity under voltage clamp conditions. When human embryonic kidney (HEK) 293 cells expressing the individual receptors were stimulated with the agonist carbachol, membrane depolarization enhanced signaling by the M1 receptor but attenuated signaling by the M3 and M5 receptors. Furthermore, whether membrane depolarization enhanced or inhibited receptor signaling depended on the type of agonist. Membrane depolarization attenuated M3 receptor signaling when the receptor was bound to carbachol or acetylcholine, whereas depolarization enhanced signaling when the receptor was bound to either choline or pilocarpine. Docking calculations predicted that there were two distinct binding modes for these ligands, which were associated with the effect of depolarization on receptor function. From these calculations, we identified a residue in the M3 receptor that, when mutated, would alter the binding mode of carbachol to resemble that of pilocarpine in silico. Introduction of this mutated M3 receptor into cells confirmed that the membrane depolarization enhanced, rather than attenuated, signaling by the carbachol-bound receptor. Together, these data suggest that the directionality of the voltage sensitivity of GPCR signaling is defined by the specific binding mode of each ligand to the receptor.
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Affiliation(s)
- Andreas Rinne
- Department of Cardiovascular Physiology, Ruhr University Bochum, Universitätsstr. 150, D-44780 Bochum, Germany
| | - Juan Carlos Mobarec
- Department of Pharmaceutical Chemistry, Philipps University Marburg, Marbacher Weg 6, D-35032 Marburg, Germany
| | - Martyn Mahaut-Smith
- Department of Cell Physiology and Pharmacology, University of Leicester, University Road, P. O. Box 138, Leicester LE1 9HN, UK
| | - Peter Kolb
- Department of Pharmaceutical Chemistry, Philipps University Marburg, Marbacher Weg 6, D-35032 Marburg, Germany
| | - Moritz Bünemann
- Department of Pharmacology and Clinical Pharmacy, Philipps University Marburg, Karl-von-Frisch-Str. 1, D-35043 Marburg, Germany.
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18
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Birk A, Rinne A, Bünemann M. Membrane Potential Controls the Efficacy of Catecholamine-induced β1-Adrenoceptor Activity. J Biol Chem 2015; 290:27311-27320. [PMID: 26408198 DOI: 10.1074/jbc.m115.665000] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Indexed: 11/06/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are membrane-located proteins and, therefore, are exposed to changes in membrane potential (V(M)) in excitable tissues. These changes have been shown to alter receptor activation of certain Gi-and Gq-coupled GPCRs. By means of a combination of whole-cell patch-clamp and Förster resonance energy transfer (FRET) in single cells, we demonstrate that the activation of the Gs-coupled β1-adrenoreceptor (β1-AR) by the catecholamines isoprenaline (Iso) and adrenaline (Adr) is regulated by V(M). This voltage-dependence is also transmitted to G protein and arrestin 3 signaling. Voltage-dependence of β2-AR activation, however, was weak compared with β1-AR voltage-dependence. Drug efficacy is a major target of β1-AR voltage-dependence as depolarization attenuated receptor activation, even under saturating concentrations of agonists, with significantly faster kinetics than the deactivation upon agonist withdrawal. Also the efficacy of the endogenous full agonist adrenaline was reduced by depolarization. This is a unique finding since reports of natural full agonists at other voltage-dependent GPCRs only show alterations in affinity during depolarization. Based on a Boltzmann function fit to the relationship of V(M) and receptor-arrestin 3 interaction we determined the voltage-dependence with highest sensitivity in the physiological range of membrane potential. Our data suggest that under physiological conditions voltage regulates the activity of agonist-occupied β1-adrenoceptors on a very fast time scale.
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Affiliation(s)
- Alexandra Birk
- Institute of Pharmacology and Clinical Pharmacy, Biochemical Pharmacological Center Marburg, Philipps-University Marburg, Karl-von-Frisch-Str. 1, 35043 Marburg, Germany and
| | - Andreas Rinne
- Institute of Physiology, Ruhr-University Bochum, Universitätsstr. 150, 44801 Bochum, Germany
| | - Moritz Bünemann
- Institute of Pharmacology and Clinical Pharmacy, Biochemical Pharmacological Center Marburg, Philipps-University Marburg, Karl-von-Frisch-Str. 1, 35043 Marburg, Germany and.
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