1
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Hazan S, Tauber M, Ben-Chaim Y. Voltage dependence of M2 muscarinic receptor antagonists and allosteric modulators. Biochem Pharmacol 2024; 227:116421. [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] [MESH Headings] [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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Ågren R, Geerdink N, Brunner HG, Paucar M, Kamsteeg EJ, Sahlholm K. An E280K Missense Variant in KCND3/Kv4.3-Case Report and Functional Characterization. Int J Mol Sci 2023; 24:10924. [PMID: 37446101 DOI: 10.3390/ijms241310924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 06/21/2023] [Accepted: 06/27/2023] [Indexed: 07/15/2023] Open
Abstract
A five-year-old girl presented with headache attacks, clumsiness, and a history of transient gait disturbances. She and her father, mother, twin sister, and brother underwent neurological evaluation, neuroimaging, and exome sequencing covering 357 genes associated with movement disorders. Sequencing revealed the new variant KCND3 c.838G>A, p.E280K in the father and sisters, but not in the mother and brother. KCND3 encodes voltage-gated potassium channel D3 (Kv4.3) and mutations have been associated with spinocerebellar ataxia type 19/22 (SCA19/22) and cardiac arrhythmias. SCA19/22 is characterized by ataxia, Parkinsonism, peripheral neuropathy, and sometimes, intellectual disability. Neuroimaging, EEG, and ECG were unremarkable. Mild developmental delay with impaired fluid reasoning was observed in both sisters, but not in the brother. None of the family members demonstrated ataxia or parkinsonism. In Xenopus oocyte electrophysiology experiments, E280K was associated with a rightward shift in the Kv4.3 voltage-activation relationship of 11 mV for WT/E280K and +17 mV for E280K/E280K relative to WT/WT. Steady-state inactivation was similarly right-shifted. Maximal peak current amplitudes were similar for WT/WT, WT/E280K, and E280K/E280K. Our data indicate that Kv4.3 E280K affects channel activation and inactivation and is associated with developmental delay. However, E280K appears to be relatively benign considering it does not result in overt ataxia.
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Affiliation(s)
- Richard Ågren
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Niels Geerdink
- Department of Pediatrics, Rijnstate Hospital, 6815 AD Arnhem, The Netherlands
| | - Han G Brunner
- Department of Human Genetics, Donders Centre for Brain, Cognition and Behavior, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
- Department of Clinical Genetics, MUMC Maastricht, GROW School for Oncology and Developmental Biology, MHENS School for Mental Health and Neuroscience, Maastricht University Medical Center, 6229 HX Maastricht, The Netherlands
| | - Martin Paucar
- Department of Neurology, Karolinska University Hospital, 141 86 Stockholm, Sweden
- Department of Clinical Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud UMC, 6525 GA Nijmegen, The Netherlands
| | - Kristoffer Sahlholm
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden
- Department of Integrative Medical Biology, Wallenberg Centre for Molecular Medicine, Umeå University, 901 87 Umeå, Sweden
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3
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Burström V, Ågren R, Betari N, Valle-León M, Garro-Martínez E, Ciruela F, Sahlholm K. Dopamine-induced arrestin recruitment and desensitization of the dopamine D4 receptor is regulated by G protein-coupled receptor kinase-2. Front Pharmacol 2023; 14:1087171. [PMID: 36778010 PMCID: PMC9911804 DOI: 10.3389/fphar.2023.1087171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 01/18/2023] [Indexed: 01/28/2023] Open
Abstract
The dopamine D4 receptor (D4R) is expressed in the retina, prefrontal cortex, and autonomic nervous system and has been implicated in attention deficit hyperactivity disorder (ADHD), substance use disorders, and erectile dysfunction. D4R has also been investigated as a target for antipsychotics due to its high affinity for clozapine. As opposed to the closely related dopamine D2 receptor (D2R), dopamine-induced arrestin recruitment and desensitization at the D4R have not been studied in detail. Indeed, some earlier investigations could not detect arrestin recruitment and desensitization of this receptor upon its activation by agonist. Here, we used a novel nanoluciferase complementation assay to study dopamine-induced recruitment of β-arrestin2 (βarr2; also known as arrestin3) and G protein-coupled receptor kinase-2 (GRK2) to the D4R in HEK293T cells. We also studied desensitization of D4R-evoked G protein-coupled inward rectifier potassium (GIRK; also known as Kir3) current responses in Xenopus oocytes. Furthermore, the effect of coexpression of GRK2 on βarr2 recruitment and GIRK response desensitization was examined. The results suggest that coexpression of GRK2 enhanced the potency of dopamine to induce βarr2 recruitment to the D4R and accelerated the rate of desensitization of D4R-evoked GIRK responses. The present study reveals new details about the regulation of arrestin recruitment to the D4R and thus increases our understanding of the signaling and desensitization of this receptor.
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Affiliation(s)
- Viktor Burström
- Department of Integrative Medical Biology, Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden
| | - Richard Ågren
- Department of Neuroscience, Karolinska Institutet, Solna, Sweden
| | - Nibal Betari
- Department of Integrative Medical Biology, Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden
| | - Marta Valle-León
- Pharmacology Unit, Department of Pathology and Experimental Therapeutics, Faculty of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, Barcelona, Spain,Neuropharmacology and Pain Group, Neuroscience Program, Institut d'Investigació Biomèdica de Bellvitge, IDIBELL, Barcelona, Spain
| | - Emilio Garro-Martínez
- Department of Integrative Medical Biology, Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden
| | - Francisco Ciruela
- Pharmacology Unit, Department of Pathology and Experimental Therapeutics, Faculty of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, Barcelona, Spain,Neuropharmacology and Pain Group, Neuroscience Program, Institut d'Investigació Biomèdica de Bellvitge, IDIBELL, Barcelona, Spain
| | - Kristoffer Sahlholm
- Department of Integrative Medical Biology, Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden,Department of Neuroscience, Karolinska Institutet, Solna, Sweden,Pharmacology Unit, Department of Pathology and Experimental Therapeutics, Faculty of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, Barcelona, Spain,Neuropharmacology and Pain Group, Neuroscience Program, Institut d'Investigació Biomèdica de Bellvitge, IDIBELL, Barcelona, Spain,*Correspondence: Kristoffer Sahlholm,
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4
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Davies A, Tomas A. Appreciating the potential for GPCR crosstalk with ion channels. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2023; 195:101-120. [PMID: 36707150 DOI: 10.1016/bs.pmbts.2022.06.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
G protein-coupled receptors (GPCRs) are expressed by most tissues in the body and are exploited pharmacologically in a variety of pathological conditions including diabetes, cardiovascular disease, neurological diseases, and cancers. Numerous cell signaling pathways can be regulated by GPCR activation, depending on the specific GPCR, ligand and cell type. Ion channels are among the many effector proteins downstream of these signaling pathways. Saliently, ion channels are also recognized as druggable targets, and there is evidence that their activity may regulate GPCR function via membrane potential and cytoplasmic ion concentration. Overall, there appears to be a large potential for crosstalk between ion channels and GPCRs. This might have implications not only for targeting GPCRs for drug development, but also opens the possibility of co-targeting them with ion channels to achieve improved therapeutic outcomes. In this review, we highlight the large variety of possible GPCR-ion channel crosstalk modes.
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Affiliation(s)
- Amy Davies
- Section of Cell Biology and Functional Genomics, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, United Kingdom
| | - Alejandra Tomas
- Section of Cell Biology and Functional Genomics, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, United Kingdom.
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5
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TAAR1 dependent and independent actions of the potential antipsychotic and dual TAAR1/5-HT 1A receptor agonist SEP-383856. Neuropsychopharmacology 2022; 47:2319-2329. [PMID: 36100653 PMCID: PMC9630386 DOI: 10.1038/s41386-022-01421-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Revised: 07/04/2022] [Accepted: 07/30/2022] [Indexed: 11/09/2022]
Abstract
SEP-383856 (SEP-856) is a novel antipsychotic under clinical development. It displays a unique pattern of receptor interaction, with only weak (partial agonist) activity at dopamine D2 receptors, yet more potent agonist activity at the trace amine associated receptor (TAAR1) and 5-hydroxytryptamine 1 A receptor (5-HT1A). Nonetheless, these observations await independent confirmation and more detailed characterization of the in vitro and in vivo actions of SEP-856 at TAAR1 and 5-HT1A receptors would be instructive. Herein, we employed luminescence complementation technology in heterologous live cell systems, confocal microscopy, voltage clamp electrophysiology, behavioral readouts and TAAR1 knockout (KO) mice to study SEP-856 in further detail. We provide evidence for the ability of SEP-856 to activate TAAR1 at the surface plasma membrane, and show that this interaction results in Gαs recruitment (pEC50: 6.08 ± 0.22 EMAX: 96.41% ± 15.26) and by extension, to G-protein inwardly rectifying potassium (GIRK) channel activation. Using TAAR1-KO mice, we find TAAR1 to be indispensable for SEP-856 control of body temperature, baseline locomotion reduction and for "antipsychotic-like" efficacy as characterized by a reversal of dizocilipine (MK-801) mediated disruption of pre-pulse inhibition. Conversely, the inhibition by SEP-856 of MK-801 induced locomotion was unaffected in TAAR1 KO mice. SEP-856 behaved as a low-potency, partial agonist at the 5-HT1A receptor, while it partially inhibited recruitment of D2 receptor-coupled Gα and GIRK by DA and acted as a weak partial agonist with low potency at the same receptor when applied alone. Our findings corroborate and extend previous observations on the molecular substrates engaged by this unique, dual TAAR1/5-HT1A receptor agonist and potential antipsychotic that could prove to have major advantages in the treatment of schizophrenia and other psychotic disorders.
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6
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David D, Bentulila Z, Tauber M, Ben-Chaim Y. G Protein-Coupled Receptors Regulated by Membrane Potential. Int J Mol Sci 2022; 23:ijms232213988. [PMID: 36430466 PMCID: PMC9696401 DOI: 10.3390/ijms232213988] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 11/09/2022] [Accepted: 11/10/2022] [Indexed: 11/16/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are involved in a vast majority of signal transduction processes. Although they span the cell membrane, they have not been considered to be regulated by the membrane potential. Numerous studies over the last two decades have demonstrated that several GPCRs, including muscarinic, adrenergic, dopaminergic, and glutamatergic receptors, are voltage regulated. Following these observations, an effort was made to elucidate the molecular basis for this regulatory effect. In this review, we will describe the advances in understanding the voltage dependence of GPCRs, the suggested molecular mechanisms that underlie this phenomenon, and the possible physiological roles that it may play.
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7
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Fluorescence-Based Measurements of Membrane-Bound Angiotensin Converting Enzyme 2 Activity Using Xenopus Laevis Oocytes. BIOSENSORS 2022; 12:bios12080601. [PMID: 36004997 PMCID: PMC9405939 DOI: 10.3390/bios12080601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 08/01/2022] [Accepted: 08/02/2022] [Indexed: 11/17/2022]
Abstract
Functional investigations of enzymes involving cellular expression systems are important for pharmacological studies. The precise control of expression is challenging in transiently transfected mammalian cell lines. Here, we explored the ability of Xenopus laevis oocytes to express a membrane-bound enzyme for functional characterization using standard 96-well plates and a fluorescence-based plate reader assay. We microinjected oocytes with cRNA encoding the angiotensin converting enzyme 2 (ACE2) and measured the enzymatic activity in single oocytes using a commercial fluorescence-based assay. The injected oocytes showed up to a 50-fold increase in fluorescence compared to uninjected oocytes. This fluorescence intensity was dose-dependent on the amount of ACE2 cRNA. These results suggest that Xenopus oocytes can be used for the functional evaluation of membrane-bound enzymes, decreasing the experimental workload.
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8
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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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9
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Ågren R, Sahlholm K. Evidence for Two Modes of Binding of the Negative Allosteric Modulator SB269,652 to the Dopamine D2 Receptor. Biomedicines 2021; 10:biomedicines10010022. [PMID: 35052702 PMCID: PMC8772941 DOI: 10.3390/biomedicines10010022] [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: 11/14/2021] [Revised: 12/21/2021] [Accepted: 12/21/2021] [Indexed: 11/16/2022] Open
Abstract
SB269,652 has been described as the first negative allosteric modulator (NAM) of the dopamine D2 receptor (D2R), however, the binding mode and allosteric mechanism of action of this ligand remain incompletely understood. SB269,652 comprises an orthosteric, primary pharmacophore and a secondary (or allosteric) pharmacophore joined by a hydrophilic cyclohexyl linker and is known to form corresponding interactions with the orthosteric binding site (OBS) and the secondary binding pocket (SBP) in the D2R. Here, we observed a surprisingly low potency of SB269,652 to negatively modulate the D2R-mediated activation of G protein-coupled inward-rectifier potassium channels (GIRK) and decided to perform a more detailed investigation of the interaction between dopamine and SB269,652. The results indicated that the SB269,652 inhibitory potency is increased 6.6-fold upon ligand pre-incubation, compared to the simultaneous co-application with dopamine. Mutagenesis experiments implicated both S193 in the OBS and E95 in the SBP in the effect of pre-application. The present findings extend previous knowledge about how SB269,652 competes with dopamine at the D2R and may be useful for the development of novel D2R ligands, such as antipsychotic drug candidates.
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Affiliation(s)
- Richard Ågren
- Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden
- Correspondence: (R.Å.); (K.S.)
| | - Kristoffer Sahlholm
- Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden
- Wallenberg Centre for Molecular Medicine, Department of Integrative Medical Biology, Umeå University, 90187 Umea, Sweden
- Correspondence: (R.Å.); (K.S.)
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10
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Ågren R, Sahlholm K. G protein-coupled receptor kinase-2 confers isoform-specific calcium sensitivity to dopamine D 2 receptor desensitization. FASEB J 2021; 35:e22013. [PMID: 34699610 DOI: 10.1096/fj.202100704rr] [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: 04/26/2021] [Revised: 10/04/2021] [Accepted: 10/11/2021] [Indexed: 11/11/2022]
Abstract
The dopamine D2 receptor (D2 R) functions as an autoreceptor on dopaminergic cell bodies and terminals and as a postsynaptic receptor on a variety of neurons in the central nervous system. As a result of alternative splicing, the D2 R is expressed as two isoforms: long (D2L R) and short (D2S R) differing by a stretch of 29 residues in the third intracellular loop, with D2S R being the predominant presynaptic isoform. Recent reports described a Ca2+ sensitivity of the desensitization time course of potassium currents elicited via D2S R, but not via D2L R, when either isoform was selectively expressed in dopaminergic neurons. Here, we aimed to study the mechanism behind this subtype-specific Ca2+ sensitivity. Thus, we measured the desensitization of potassium channel responses evoked by D2L R and D2S R using two-electrode voltage clamp in Xenopus oocytes in the absence and presence of different amounts of β-arrestin2 and G protein-coupled receptor kinase-2 (GRK2), both of which are known to play important roles in D2 R desensitization in native cells. We found that co-expression of both GRK2 and β-arrestin2 was necessary for reconstitution of the Ca2+ sensitivity of D2S R desensitization, while D2L R did not display Ca2+ sensitivity under these conditions. The effect of Ca2+ chelation by BAPTA-AM to slow the rate of D2S R desensitization was mimicked by the GRK2 inhibitor, Cmpd101, and by the kinase-inactivating GRK2 mutation, K220R, but not by the PKC inhibitor, Gö6976, nor by the calmodulin antagonist, KN-93. Thus, Ca2+ -sensitive desensitization of D2S R appears to be mediated via a GRK2 phosphorylation-dependent mechanism.
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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, Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden
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Dopamine D 2 Receptor Agonist Binding Kinetics-Role of a Conserved Serine Residue. Int J Mol Sci 2021; 22:ijms22084078. [PMID: 33920848 PMCID: PMC8071183 DOI: 10.3390/ijms22084078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/06/2021] [Accepted: 04/13/2021] [Indexed: 01/03/2023] Open
Abstract
The forward (kon) and reverse (koff) rate constants of drug–target interactions have important implications for therapeutic efficacy. Hence, time-resolved assays capable of measuring these binding rate constants may be informative to drug discovery efforts. Here, we used an ion channel activation assay to estimate the kons and koffs of four dopamine D2 receptor (D2R) agonists; dopamine (DA), p-tyramine, (R)- and (S)-5-OH-dipropylaminotetralin (DPAT). We further probed the role of the conserved serine S1935.42 by mutagenesis, taking advantage of the preferential interaction of (S)-, but not (R)-5-OH-DPAT with this residue. Results suggested similar koffs for the two 5-OH-DPAT enantiomers at wild-type (WT) D2R, both being slower than the koffs of DA and p-tyramine. Conversely, the kon of (S)-5-OH-DPAT was estimated to be higher than that of (R)-5-OH-DPAT, in agreement with the higher potency of the (S)-enantiomer. Furthermore, S1935.42A mutation lowered the kon of (S)-5-OH-DPAT and reduced the potency difference between the two 5-OH-DPAT enantiomers. Kinetic Kds derived from the koff and kon estimates correlated well with EC50 values for all four compounds across four orders of magnitude, strengthening the notion that our assay captured meaningful information about binding kinetics. The approach presented here may thus prove valuable for characterizing D2R agonist candidate drugs.
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12
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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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13
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Ågren R, Zeberg H, Stępniewski TM, Free RB, Reilly SW, Luedtke RR, Århem P, Ciruela F, Sibley DR, Mach RH, Selent J, Nilsson J, Sahlholm K. Ligand with Two Modes of Interaction with the Dopamine D 2 Receptor-An Induced-Fit Mechanism of Insurmountable Antagonism. ACS Chem Neurosci 2020; 11:3130-3143. [PMID: 32865974 PMCID: PMC7553383 DOI: 10.1021/acschemneuro.0c00477] [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] [Indexed: 12/11/2022] Open
Abstract
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A solid
understanding of the mechanisms governing ligand binding
is crucial for rational design of therapeutics targeting the dopamine
D2 receptor (D2R). Here, we use G protein-coupled
inward rectifier potassium (GIRK) channel activation in Xenopus oocytes to measure the kinetics of D2R antagonism by
a series of aripiprazole analogues, as well as the recovery of dopamine
(DA) responsivity upon washout. The aripiprazole analogues comprise
an orthosteric and a secondary pharmacophore and differ by the length
of the saturated carbon linker joining these two pharmacophores. Two
compounds containing 3- and 5-carbon linkers allowed for a similar
extent of recovery from antagonism in the presence of 1 or 100 μM
DA (>25 and >90% of control, respectively), whereas recovery
was less
prominent (∼20%) upon washout of the 4-carbon linker compound,
SV-III-130, both with 1 and 100 μM DA. Prolonging the coincubation
time with SV-III-130 further diminished recovery. Curve-shift experiments
were consistent with competition between SV-III-130 and DA. Two mutations
in the secondary binding pocket (V91A and E95A) of D2R
decreased antagonistic potency and increased recovery from SV-III-130
antagonism, whereas a third mutation (L94A) only increased recovery.
Our results suggest that the secondary binding pocket influences recovery
from inhibition by the studied aripiprazole analogues. We propose
a mechanism, supported by in silico modeling, whereby
SV-III-130 initially binds reversibly to the D2R, after
which the drug-receptor complex undergoes a slow transition to a second
ligand-bound state, which is dependent on secondary binding pocket
integrity and irreversible during the time frame of our experiments.
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Affiliation(s)
- Richard Ågren
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm 171 77, Sweden
- Department of Neuroscience, Karolinska Institutet, Stockholm 171 77, Sweden
| | - Hugo Zeberg
- Department of Neuroscience, Karolinska Institutet, Stockholm 171 77, Sweden
| | - Tomasz Maciej Stępniewski
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences of Pompeu Fabra University (UPF)-Hospital del Mar Medical Research Institute (IMIM), 08003 Barcelona, Spain
- InterAx Biotech AG, PARK innovAARE, 5234 Villigen, Switzerland
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Warsaw 02-089, Poland
| | - R. Benjamin Free
- Molecular Neuropharmacology Section, National Institute of Neurological Disorders and Stroke, Intramural Research Program, National Institutes of Health, Bethesda, Maryland 20892-3723, United States
| | - Sean W. Reilly
- Department of Radiology, Division of Nuclear Medicine and Clinical Molecular Imaging, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104, United States
| | - Robert R. Luedtke
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, Texas 76107, United States
| | - Peter Århem
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm 171 77, Sweden
- Department of Neuroscience, Karolinska Institutet, Stockholm 171 77, Sweden
| | - Francisco Ciruela
- Pharmacology Unit, Department of Pathology and Experimental Therapeutics, Faculty of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, L’Hospitalet de Llobregat 08907, Spain
- Neuropharmacology and Pain Group, Neuroscience Program, Institut d’Investigació Biomèdica de Bellvitge, IDIBELL, L’Hospitalet de Llobregat 08907, Spain
| | - David R. Sibley
- Molecular Neuropharmacology Section, National Institute of Neurological Disorders and Stroke, Intramural Research Program, National Institutes of Health, Bethesda, Maryland 20892-3723, United States
| | - Robert H. Mach
- Department of Radiology, Division of Nuclear Medicine and Clinical Molecular Imaging, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104, United States
| | - Jana Selent
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences of Pompeu Fabra University (UPF)-Hospital del Mar Medical Research Institute (IMIM), 08003 Barcelona, Spain
| | - Johanna Nilsson
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm 171 77, Sweden
| | - Kristoffer Sahlholm
- Department of Neuroscience, Karolinska Institutet, Stockholm 171 77, Sweden
- Department of Integrative Medical Biology, Umeå University, Umeå 901 87, Sweden
- Wallenberg Centre for Molecular Medicine, Umeå University, Umeå 901 87, Sweden
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14
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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: 5] [Impact Index Per Article: 1.3] [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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15
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Kurz M, Krett AL, Bünemann M. Voltage Dependence of Prostanoid Receptors. Mol Pharmacol 2020; 97:267-277. [DOI: 10.1124/mol.119.118372] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 01/25/2020] [Indexed: 12/16/2022] Open
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16
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Ben-Chaim Y, Broide C, Parnas H. The coupling of the M2 muscarinic receptor to its G protein is voltage dependent. PLoS One 2019; 14:e0224367. [PMID: 31671117 PMCID: PMC6822938 DOI: 10.1371/journal.pone.0224367] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 10/10/2019] [Indexed: 11/18/2022] Open
Abstract
G protein coupled receptors (GPCRs) participate in the majority of signal transduction processes in the body. Specifically, the binding of an external agonist promotes coupling of the GPCR to its G protein and this, in turn, induces downstream signaling. Recently, it was shown that agonist binding to the M2 muscarinic receptor (M2R) and to other GPCRs is voltage dependent. Here we examine, whether the coupling of the M2R to its G protein is also voltage-dependent. We first show, in Xenopus oocytes, that the activity of the M2R in the absence of agonist (constitutive activity) can be used to report the coupling. We then show that the coupling is, by itself, voltage dependent. This novel finding is of physiological importance, as it shows that the actual signal transduction, whose first step is the coupling of the GPCR to its cognate G protein, is voltage dependent.
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Affiliation(s)
- Yair Ben-Chaim
- Department of Natural and Life Sciences, The Open University of Israel, Ra'anana, Israel
- * E-mail: (HP); (YBC)
| | - Chava Broide
- Department of Neurobiology, Institute of Life Sciences, The Hebrew University, Jerusalem, Israel
| | - Hanna Parnas
- Department of Neurobiology, Institute of Life Sciences, The Hebrew University, Jerusalem, Israel
- * E-mail: (HP); (YBC)
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17
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Shalaeva DN, Cherepanov DA, Galperin MY, Vriend G, Mulkidjanian AY. G protein-coupled receptors of class A harness the energy of membrane potential to increase their sensitivity and selectivity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:183051. [PMID: 31449800 DOI: 10.1016/j.bbamem.2019.183051] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 07/28/2019] [Accepted: 08/21/2019] [Indexed: 12/31/2022]
Abstract
The human genome contains about 700 genes of G protein-coupled receptors (GPCRs) of class A; these seven-helical membrane proteins are the targets of almost half of all known drugs. In the middle of the helix bundle, crystal structures reveal a highly conserved sodium-binding site, which is connected with the extracellular side by a water-filled tunnel. This binding site contains a sodium ion in those GPCRs that are crystallized in their inactive conformations but does not in those GPCRs that are trapped in agonist-bound active conformations. The escape route of the sodium ion upon the inactive-to-active transition and its very direction have until now remained obscure. Here, by modeling the available experimental data, we show that the sodium gradient over the cell membrane increases the sensitivity of GPCRs if their activation is thermodynamically coupled to the sodium ion translocation into the cytoplasm but decreases it if the sodium ion retreats into the extracellular space upon receptor activation. The model quantitatively describes the available data on both activation and suppression of distinct GPCRs by membrane voltage. The model also predicts selective amplification of the signal from (endogenous) agonists if only they, but not their (partial) analogs, induce sodium translocation. Comparative structure and sequence analyses of sodium-binding GPCRs indicate a key role for the conserved leucine residue in the second transmembrane helix (Leu2.46) in coupling sodium translocation to receptor activation. Hence, class A GPCRs appear to harness the energy of the transmembrane sodium potential to increase their sensitivity and selectivity.
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Affiliation(s)
- Daria N Shalaeva
- School of Physics, Osnabrueck University, 49069 Osnabrück, Germany; A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia.
| | - Dmitry A Cherepanov
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia; N.N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow, Russia.
| | - Michael Y Galperin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA.
| | - Gert Vriend
- Centre for Molecular and Biomolecular Informatics, Radboud University Medical Centre, 6525 HP Nijmegen, the Netherlands.
| | - Armen Y Mulkidjanian
- School of Physics, Osnabrueck University, 49069 Osnabrück, Germany; A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia; School of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119991, Russia.
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18
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Ågren R, Århem P, Nilsson J, Sahlholm K. The Beta-Arrestin-Biased Dopamine D2 Receptor Ligand, UNC9994, Is a Partial Agonist at G-Protein-Mediated Potassium Channel Activation. Int J Neuropsychopharmacol 2018; 21:1102-1108. [PMID: 29986044 PMCID: PMC6276031 DOI: 10.1093/ijnp/pyy059] [Citation(s) in RCA: 11] [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: 03/14/2018] [Accepted: 07/03/2018] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Previous evidence suggests that UNC9994 is a beta-arrestin2-selective agonist at the dopamine D2 receptor, lacking ability both to activate and antagonize G protein-dependent signaling. However, this has only been reported by one laboratory using a single assay. METHODS We used G protein-coupled inward rectifier potassium channel activation in Xenopus oocytes to investigate UNC9994-induced modulation of G protein-dependent signaling at dopamine D2 receptor and dopamine D3 receptor. RESULTS At dopamine D2 receptor, UNC9994 induced G protein-coupled inward rectifier potassium channel currents that were 15% of the maximal response to dopamine, with an EC50 of 185 nM. At dopamine D3 receptor, the ligand elicited 89% of the maximal dopamine response with an EC50 of 62 nM. Pertussis toxin abolished G protein-coupled inward rectifier potassium channel activation. Furthermore, UNC9994 antagonized dopamine-induced G protein-coupled inward rectifier potassium channel activation at dopamine D2 receptor. CONCLUSIONS UNC9994 modulates G protein-coupled inward rectifier potassium channel channel activation via pertussis toxin-sensitive G proteins at dopamine D2 receptor and dopamine D3 receptor. These findings may have implications for the interpretation of data obtained with this ligand.
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Affiliation(s)
- Richard Ågren
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden,Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Peter Århem
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Johanna Nilsson
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden,Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Kristoffer Sahlholm
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden,Correspondence: Kristoffer Sahlholm, PhD, Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 17177, Stockholm, Sweden ()
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19
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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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20
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Barchad-Avitzur O, Priest MF, Dekel N, Bezanilla F, Parnas H, Ben-Chaim Y. A Novel Voltage Sensor in the Orthosteric Binding Site of the M2 Muscarinic Receptor. Biophys J 2017; 111:1396-1408. [PMID: 27705763 DOI: 10.1016/j.bpj.2016.08.035] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 08/28/2016] [Accepted: 08/31/2016] [Indexed: 12/31/2022] Open
Abstract
G protein-coupled receptors (GPCRs) mediate many signal transduction processes in the body. The discovery that these receptors are voltage-sensitive has changed our understanding of their behavior. The M2 muscarinic acetylcholine receptor (M2R) was found to exhibit depolarization-induced charge movement-associated currents, implying that this prototypical GPCR possesses a voltage sensor. However, the typical domain that serves as a voltage sensor in voltage-gated channels is not present in GPCRs, making the search for the voltage sensor in the latter challenging. Here, we examine the M2R and describe a voltage sensor that is comprised of tyrosine residues. This voltage sensor is crucial for the voltage dependence of agonist binding to the receptor. The tyrosine-based voltage sensor discovered here constitutes a noncanonical by which membrane proteins may sense voltage.
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Affiliation(s)
- Ofra Barchad-Avitzur
- Department of Neurobiology, Institute of Life Sciences, The Hebrew University, Jerusalem, Israel
| | - Michael F Priest
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois
| | - Noa Dekel
- Department of Neurobiology, Institute of Life Sciences, The Hebrew University, Jerusalem, Israel
| | - Francisco Bezanilla
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois
| | - Hanna Parnas
- Department of Neurobiology, Institute of Life Sciences, The Hebrew University, Jerusalem, Israel
| | - Yair Ben-Chaim
- Natural and Life Sciences, Open University of Israel, Raanana, Israel.
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21
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Moreno-Galindo EG, Sanchez-Chapula JA, Tristani-Firouzi M, Navarro-Polanco RA. Pharmacological Conversion of a Cardiac Inward Rectifier into an Outward Rectifier Potassium Channel. Mol Pharmacol 2016; 90:334-40. [PMID: 27247338 DOI: 10.1124/mol.116.104950] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 05/27/2016] [Indexed: 01/20/2023] Open
Abstract
Potassium (K(+)) channels are crucial for determining the shape, duration, and frequency of action-potential firing in excitable cells. Broadly speaking, K(+) channels can be classified based on whether their macroscopic current outwardly or inwardly rectifies, whereby rectification refers to a change in conductance with voltage. Outwardly rectifying K(+) channels conduct greater current at depolarized membrane potentials, whereas inward rectifier channels conduct greater current at hyperpolarized membrane potentials. Under most circumstances, outward currents through inwardly rectifying K(+) channels are reduced at more depolarized potentials. However, the acetylcholine-gated K(+) channel (KACh) conducts current that inwardly rectifies when activated by some ligands (such as acetylcholine), and yet conducts current that outwardly rectifies when activated by other ligands (for example, pilocarpine and choline). The perplexing and paradoxical behavior of KACh channels is due to the intrinsic voltage sensitivity of the receptor that activates KACh channels, the M2 muscarinic receptor (M2R). Emerging evidence reveals that the affinity of M2R for distinct ligands varies in a voltage-dependent and ligand-specific manner. These intrinsic receptor properties determine whether current conducted by KACh channels inwardly or outwardly rectifies. This review summarizes the most recent concepts regarding the intrinsic voltage sensitivity of muscarinic receptors and the consequences of this intriguing behavior on cardiac physiology and pharmacology of KACh channels.
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Affiliation(s)
- Eloy G Moreno-Galindo
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Colima, México (E.G.M.-G., J.A.S.-C., R.A.N.-P.); Nora Eccles Harrison Cardiovascular Research and Training Institute, and Division of Pediatric Cardiology, University of Utah, Salt Lake City, Utah (M.T.-F.)
| | - Jose A Sanchez-Chapula
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Colima, México (E.G.M.-G., J.A.S.-C., R.A.N.-P.); Nora Eccles Harrison Cardiovascular Research and Training Institute, and Division of Pediatric Cardiology, University of Utah, Salt Lake City, Utah (M.T.-F.)
| | - Martin Tristani-Firouzi
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Colima, México (E.G.M.-G., J.A.S.-C., R.A.N.-P.); Nora Eccles Harrison Cardiovascular Research and Training Institute, and Division of Pediatric Cardiology, University of Utah, Salt Lake City, Utah (M.T.-F.)
| | - Ricardo A Navarro-Polanco
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Colima, México (E.G.M.-G., J.A.S.-C., R.A.N.-P.); Nora Eccles Harrison Cardiovascular Research and Training Institute, and Division of Pediatric Cardiology, University of Utah, Salt Lake City, Utah (M.T.-F.)
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22
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Moreno-Galindo EG, Alamilla J, Sanchez-Chapula JA, Tristani-Firouzi M, Navarro-Polanco RA. The agonist-specific voltage dependence of M2 muscarinic receptors modulates the deactivation of the acetylcholine-gated K(+) current (I KACh). Pflugers Arch 2016; 468:1207-1214. [PMID: 27023349 DOI: 10.1007/s00424-016-1812-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 02/22/2016] [Accepted: 03/16/2016] [Indexed: 11/26/2022]
Abstract
Recently, it has been shown that G protein-coupled receptors (GPCRs) display intrinsic voltage sensitivity. We reported that the voltage sensitivity of M2 muscarinic receptor (M2R) is also ligand specific. Here, we provide additional evidence to understand the mechanism underlying the ligand-specific voltage sensitivity of the M2R. Using ACh, pilocarpine (Pilo), and bethanechol (Beth), we evaluated the agonist-specific effects of voltage by measuring the ACh-activated K(+) current (I KACh) in feline and rabbit atrial myocytes and in HEK-293 cells expressing M2R-Kir3.1/Kir3.4. The activation of I KACh by the muscarinic agonist Beth was voltage insensitive, suggesting that the voltage-induced conformational changes in M2R do not modify its affinity for this agonist. Moreover, deactivation of the Beth-evoked I KACh was voltage insensitive. By contrast, deactivation of the ACh-induced I KACh was significantly slower at -100 mV than at +50 mV, while an opposite effect was observed when I KACh was activated by Pilo. These findings are consistent with the voltage affinity pattern observed for these three agonists. Our findings suggest that independent of how voltage disturbs the receptor binding site, the voltage dependence of the signaling pathway is ultimately determined by the agonist. These observations emphasize the pharmacological potential to regulate the M2R-parasympathetic associated cardiac function and also other cellular signaling pathways by exploiting the voltage-dependent properties of GPCRs.
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Affiliation(s)
- Eloy G Moreno-Galindo
- Centro Universitario de Investigaciones Biomedicas, C.U.I.B, Universidad de Colima, Av. 25 de Julio 965, Colonia Villa San Sebastián, 28045, Colima, COL, Mexico
| | | | - José A Sanchez-Chapula
- Centro Universitario de Investigaciones Biomedicas, C.U.I.B, Universidad de Colima, Av. 25 de Julio 965, Colonia Villa San Sebastián, 28045, Colima, COL, Mexico
| | - Martin Tristani-Firouzi
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - Ricardo A Navarro-Polanco
- Centro Universitario de Investigaciones Biomedicas, C.U.I.B, Universidad de Colima, Av. 25 de Julio 965, Colonia Villa San Sebastián, 28045, Colima, COL, Mexico.
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23
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Sahlholm K, Zeberg H, Nilsson J, Ögren SO, Fuxe K, Århem P. The fast-off hypothesis revisited: A functional kinetic study of antipsychotic antagonism of the dopamine D2 receptor. Eur Neuropsychopharmacol 2016; 26:467-76. [PMID: 26811292 DOI: 10.1016/j.euroneuro.2016.01.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 12/02/2015] [Accepted: 01/11/2016] [Indexed: 11/28/2022]
Abstract
Newer, "atypical" antipsychotics carry a lower risk of motor side-effects than older, "typical" compounds. It has been proposed that a ~100-fold faster dissociation from the dopamine D2 receptor (D2R) distinguishes atypical from typical antipsychotics. Furthermore, differing antipsychotic D2R affinities have been suggested to reflect differences in dissociation rate constants (koff), while association rate constants (kon) were assumed to be similar. However, it was recently demonstrated that lipophilic accumulation of ligand in the cell interior and/or membrane can cause underestimation of koff, and as high-affinity D2R antagonists are frequently lipophilic, this may have been a confounding factor in previous studies. In the present work, a functional electrophysiology assay was used to measure the recovery of dopamine-mediated D2R responsivity from antipsychotic antagonism, using elevated concentrations of dopamine to prevent the potential bias of re-binding of lipophilic ligands. The variability of antipsychotic kon was also reexamined, capitalizing on the temporal resolution of the assay. kon was estimated from the experimental recordings using a simple mathematical model assumed to describe the binding process. The time course of recovery from haloperidol (typical antipsychotic) was only 6.4- to 2.5-fold slower than that of the atypical antipsychotics, amisulpride, clozapine, and quetiapine, while antipsychotic kons were found to vary more widely than previously suggested. Finally, affinities calculated using our kon and koff estimates correlated well with functional potency and with affinities reported from radioligand binding studies. In light of these findings, it appears unlikely that typical and atypical antipsychotics are primarily distinguished by their D2R binding kinetics.
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Affiliation(s)
- Kristoffer Sahlholm
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, SE-171 77 Stockholm, Sweden.
| | - Hugo Zeberg
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, SE-171 77 Stockholm, Sweden
| | - Johanna Nilsson
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, SE-171 77 Stockholm, Sweden
| | - Sven Ove Ögren
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, SE-171 77 Stockholm, Sweden
| | - Kjell Fuxe
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, SE-171 77 Stockholm, Sweden
| | - Peter Århem
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, SE-171 77 Stockholm, Sweden
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24
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Agnati LF, Guidolin D, Cervetto C, Borroto-Escuela DO, Fuxe K. Role of iso-receptors in receptor-receptor interactions with a focus on dopamine iso-receptor complexes. Rev Neurosci 2016; 27:1-25. [DOI: 10.1515/revneuro-2015-0024] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 07/27/2015] [Indexed: 12/17/2022]
Abstract
AbstractIntercellular and intracellular communication processes consist of signals and recognition/decoding apparatuses of these signals. In humans, the G protein-coupled receptor (GPCR) family represents the largest family of cell surface receptors. More than 30 years ago, it has been proposed that GPCR could form dimers or higher-order oligomers (receptor mosaics [RMs] at the plasma membrane level and receptor-receptor interactions [RRIs] have been proposed as a new integrative mechanism for chemical signals impinging on cell plasma membranes). The basic phenomena involved in RRIs are allostery and cooperativity of membrane receptors, and the present paper provides basic information concerning their relevance for the integrative functions of RMs. In this context, the possible role of iso-receptor RM is discussed (with a special focus on dopamine receptor subtypes and on some of the RMs they form with other dopamine iso-receptors), and it is proposed that two types of cooperativity, namely, homotropic and heterotropic cooperativity, could allow distinguishing two types of functionally different RMs. From a general point of view, the presence of iso-receptors and their topological organization within RMs allow the use of a reduced number of signals for the intercellular communication processes, since the target cells can recognize and decode the same signal in different ways. This theoretical aspect is further analyzed here by means of an analogy with artificial information systems. Thus, it is suggested that the ‘multiplexer’ and ‘demultiplexer’ concepts could, at least in part, model the role of RMs formed by iso-receptors in the information handling by the cell.
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Affiliation(s)
- Luigi F. Agnati
- 1Department of Biomedical Sciences, University of Modena and Reggio Emilia, Modena, Via Campi 287, 41100 Modena, Italy
| | - Diego Guidolin
- 2Department of Molecular Medicine, University of Padova, Via Gabelli 65, 35121 Padova, Italy
| | - Chiara Cervetto
- 3Department of Pharmacy, University of Genova, Viale Cembrano 4, 16147 Genova, Italy
| | | | - Kjell Fuxe
- 4Department of Neuroscience, Karolinska Institutet, Retzius vag 8, 17177 Stockholm, Sweden
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25
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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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Ma GF, Raivio N, Sabrià J, Ortiz J. Agonist and antagonist effects of aripiprazole on D₂-like receptors controlling rat brain dopamine synthesis depend on the dopaminergic tone. Int J Neuropsychopharmacol 2015; 18:pyu046. [PMID: 25522390 PMCID: PMC4360222 DOI: 10.1093/ijnp/pyu046] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The atypical antipsychotic drug aripiprazole binds with high affinity to a number of G protein coupled receptors, including dopamine D₂ receptors, where its degree of efficacy as a partial agonist remains controversial. METHODS We examined the properties of aripiprazole at D₂-like autoreceptors by monitoring the changes of dopamine synthesis in adult rat brain striatal minces incubated ex vivo. The effects of the dopaminergic tone on the properties of aripiprazole were assayed by comparing a basal condition (2 mM K(+), low dopaminergic tone) and a stimulated condition (15 mM K(+), where dopamine release mimics a relatively higher dopaminergic tone). We also used 2 reference compounds: quinpirole showed a clear agonistic activity and preclamol (S-(-)-PPP) showed partial agonism under both basal and stimulated conditions. RESULTS Aripiprazole under the basal condition acted as an agonist at D₂-like autoreceptors and fully activated them at about 10 nM, inhibiting dopamine synthesis similarly to quinpirole. Higher concentrations of aripiprazole had effects not restricted to D₂-like autoreceptor activation. Under the stimulated (15 mM K(+)) condition, nanomolar concentrations of aripiprazole failed to decrease dopamine synthesis but could totally block the effect of quinpirole. CONCLUSIONS Under high dopaminergic tone, aripiprazole acts as a D₂-like autoreceptor antagonist rather than as an agonist. These data show that, ex vivo, alteration of dopaminergic tone by depolarization affects the actions of aripiprazole on D₂-like autoreceptors. Such unusual effects were not seen with the typical partial agonist preclamol and are consistent with the hypothesis that aripiprazole is a functionally selective D₂R ligand.
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Affiliation(s)
| | | | | | - Jordi Ortiz
- Neuroscience Institute and Department of Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona, Barcelona, Spain.
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Typical and atypical antipsychotics do not differ markedly in their reversibility of antagonism of the dopamine D2 receptor. Int J Neuropsychopharmacol 2014; 17:149-55. [PMID: 24074141 DOI: 10.1017/s1461145713000801] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
It has been suggested that the favorable side-effect profiles of atypical antipsychotics (e.g. clozapine and amisulpride) are related to their ∼100-fold faster dissociation from dopamine D2 receptors (D2R) compared with typical antipsychotics (e.g. haloperidol and chlorpromazine). Fast dissociation would entail rapidly reversible antagonism; however, this has not been thoroughly studied using functional assays. We compared the reversibilities of D2R antagonism by 17 compounds using an electrophysiological method to measure dopamine-evoked potassium channel activation via D2R. Varying rates and amplitudes of D2R response recovery were observed following antagonist removal. Whereas recovery rates differed 15-fold between atypical drugs, recovery from clozapine and amisulpride antagonism was, unexpectedly, less than twofold faster than from chlorpromazine. The recovery amplitude correlated with calculated water solubility and lipid/water distribution coefficients, suggesting variable drug partitioning into cell membranes. Our data do not support the notion that the rate of reversibility of D2R antagonism is what distinguishes atypical from typical antipsychotics.
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Ben Chaim Y, Bochnik S, Parnas I, Parnas H. Voltage affects the dissociation rate constant of the m2 muscarinic receptor. PLoS One 2013; 8:e74354. [PMID: 24019965 PMCID: PMC3760861 DOI: 10.1371/journal.pone.0074354] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 08/05/2013] [Indexed: 11/18/2022] Open
Abstract
G-protein coupled receptors (GPCRs) comprise the largest protein family and mediate the vast majority of signal transduction processes in the body. Until recently GPCRs were not considered to be voltage dependent. Newly it was shown for several GPCRs that the first step in GPCR activation, the binding of agonist to the receptor, is voltage sensitive: Voltage shifts the receptor between two states that differ in their binding affinity. Here we show that this shift involves the rate constant of dissociation. We used the m2 muscarinic receptor (m2R) a prototypical GPCR and measured directly the dissociation of [(3)H]ACh from m2R expressed Xenopus oocytes. We show, for the first time, that the voltage dependent change in affinity is implemented by voltage shifting the receptor between two states that differ in their rate constant of dissociation. Furthermore, we provide evidence that suggest that the above shift is achieved by voltage regulating the coupling of the GPCR to its G protein.
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Affiliation(s)
- Yair Ben Chaim
- Department of Natural and Life Sciences, The Open University of Israel, Ra’anana, Israel
| | - Shimrit Bochnik
- Department of Neurobiology, Institute of Life Sciences, The Hebrew University, Jerusalem, Israel
| | - Itzchak Parnas
- Department of Neurobiology, Institute of Life Sciences, The Hebrew University, Jerusalem, Israel
| | - Hanna Parnas
- Department of Neurobiology, Institute of Life Sciences, The Hebrew University, Jerusalem, Israel
- * E-mail:
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Voltage sensitivities and deactivation kinetics of histamine H3 and H4 receptors. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:3081-9. [DOI: 10.1016/j.bbamem.2012.07.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Revised: 07/25/2012] [Accepted: 07/27/2012] [Indexed: 11/17/2022]
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Sahlholm K. The role of RGS protein in agonist-dependent relaxation of GIRK currents in Xenopus oocytes. Biochem Biophys Res Commun 2011; 415:509-14. [PMID: 22068057 DOI: 10.1016/j.bbrc.2011.10.106] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Accepted: 10/22/2011] [Indexed: 01/28/2023]
Abstract
G protein coupled inward rectifier K(+) channels (GIRK) are activated by the G(βγ) subunits of G proteins upon activation of G protein coupled receptors (GPCRs). Receptor-stimulated GIRK currents are known to possess a curious property, termed "agonist-dependent relaxation," denoting a slow current increase upon stepping the membrane voltage from positive to negative potentials. Regulators of G protein signaling (RGS) proteins have earlier been implicated in this phenomenon since RGS coexpression was required for relaxation to be observed in heterologous expression systems. However, a recent study presented contrasting evidence that GIRK current relaxation reflects voltage sensitive agonist binding to the GPCR. The present study re-examined the role of RGS protein in agonist-dependent relaxation and found that RGS coexpression is not necessary for the relaxation phenomenon. However, RGS4 speeds up relaxation kinetics, allowing the phenomenon to be observed using shorter voltage steps. These findings resolve the controversy regarding the role of RGS protein vs. GPCR voltage sensitivity in mediating agonist-dependent relaxation of GIRK currents.
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Affiliation(s)
- Kristoffer Sahlholm
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden.
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