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Rinne A, Bünemann M. Charge Movements and Conformational Changes: Biophysical Properties and Physiology of Voltage-Dependent GPCRs. Biomolecules 2024; 14:1652. [PMID: 39766359 PMCID: PMC11674552 DOI: 10.3390/biom14121652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2024] [Revised: 12/10/2024] [Accepted: 12/17/2024] [Indexed: 01/11/2025] Open
Abstract
G protein-coupled receptors (GPCRs) regulate multiple cellular functions and represent important drug targets. More than 20 years ago, it was noted that GPCR activation (agonist binding) and signaling (G protein activation) are dependent on the membrane potential (VM). While it is now proven that many GPCRs display an intrinsic voltage dependence, the molecular mechanisms of how GPCRs sense depolarization of the plasma membrane are less well defined. This review summarizes the current knowledge of voltage-dependent signaling in GPCRs. We describe how voltage dependence was discovered in muscarinic receptors, present an overview of GPCRs that are regulated by voltage, and show how biophysical properties of GPCRs led to the discovery of voltage-sensing mechanisms in those receptors. Furthermore, we summarize physiological functions that have been shown to be regulated by voltage-dependent GPCR signaling of endogenous receptors in excitable tissues, such as the nervous system or the heart. Finally, we discuss challenges that remain in analyzing voltage-dependent signaling of GPCRs in vivo and present an outlook on experimental applications of the interesting concept of GPCR signaling.
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Affiliation(s)
- Andreas Rinne
- Department of Biophysics and Cellular Biotechnology, “Carol Davila” University of Medicine and Pharmacy Bucharest, 050474 Bucharest, Romania
| | - Moritz Bünemann
- Institute of Pharmacology and Clinical Pharmacy, Biochemical Pharmaceutical Center (BPC) Marburg, University of Marburg, 35043 Marburg, Germany
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2
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Boutonnet M, Bünemann M, Perroy J. The voltage sensitivity of G-protein coupled receptors: Unraveling molecular mechanisms and physiological implications. Pharmacol Ther 2024; 264:108741. [PMID: 39489434 DOI: 10.1016/j.pharmthera.2024.108741] [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: 07/16/2024] [Revised: 09/11/2024] [Accepted: 10/29/2024] [Indexed: 11/05/2024]
Abstract
In the landscape of proteins controlled by membrane voltage (Vm), like voltage-gated ionotropic channels, the emergence of the voltage sensitivity within the vast family of G-protein coupled receptors (GPCRs) marked a significant milestone at the onset of the 21st century. Since its discovery, extensive research has been devoted to understanding the intricate relationship between Vm and GPCRs. Approximately 30 GPCRs out of a family comprising more than 800 receptors have been implicated in Vm-dependent positive and negative regulation. GPCRs stand out as the quintessential regulators of synaptic transmission in neurons, where they encounter substantial variations in Vm. However, the molecular mechanism underlying the Vm sensor of GPCRs remains enigmatic, hindered by the scarcity of mutant GPCRs insensitive to Vm yet functionally intact, impeding a comprehensive understanding of this unique property in physiology. Nevertheless, two decades of dedicated research have furnished numerous insights into the molecular aspects of GPCR Vm-sensing, accompanied by recently proposed physiological roles as well as pharmacological potential, which we encapsulate in this review. The Vm sensitivity of GPCRs emerges as a pivotal attribute, shedding light on previously unforeseen roles in synaptic transmission and extending beyond, underscoring its significance in cellular signaling and physiological processes.
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Affiliation(s)
- Marin Boutonnet
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Moritz Bünemann
- Department of Pharmacology and Clinical Pharmacy, Philipps-University Marburg, Marburg, Germany
| | - Julie Perroy
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France.
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3
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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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Kirchhofer SB, Lim VJY, Ernst S, Karsai N, Ruland JG, Canals M, Kolb P, Bünemann M. Differential interaction patterns of opioid analgesics with µ opioid receptors correlate with ligand-specific voltage sensitivity. eLife 2023; 12:e91291. [PMID: 37983079 PMCID: PMC10849675 DOI: 10.7554/elife.91291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 11/19/2023] [Indexed: 11/21/2023] Open
Abstract
The µ opioid receptor (MOR) is the key target for analgesia, but the application of opioids is accompanied by several issues. There is a wide range of opioid analgesics, differing in their chemical structure and their properties of receptor activation and subsequent effects. A better understanding of ligand-receptor interactions and the resulting effects is important. Here, we calculated the respective binding poses for several opioids and analyzed interaction fingerprints between ligand and receptor. We further corroborated the interactions experimentally by cellular assays. As MOR was observed to display ligand-induced modulation of activity due to changes in membrane potential, we further analyzed the effects of voltage sensitivity on this receptor. Combining in silico and in vitro approaches, we defined discriminating interaction patterns responsible for ligand-specific voltage sensitivity and present new insights into their specific effects on activation of the MOR.
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Affiliation(s)
- Sina B Kirchhofer
- Department of Pharmacology and Clinical Pharmacy, University of MarburgMarburgGermany
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen's Medical Centre, University of NottinghamNottinghamUnited Kingdom
- Centre of Membrane Protein and Receptors, Universities of Birmingham and NottinghamMidlandsUnited Kingdom
| | - Victor Jun Yu Lim
- Department of Pharmaceutical Chemistry, University of MarburgMarburgGermany
| | - Sebastian Ernst
- Department of Pharmacology and Clinical Pharmacy, University of MarburgMarburgGermany
| | - Noemi Karsai
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen's Medical Centre, University of NottinghamNottinghamUnited Kingdom
- Centre of Membrane Protein and Receptors, Universities of Birmingham and NottinghamMidlandsUnited Kingdom
| | - Julia G Ruland
- Department of Pharmacology and Clinical Pharmacy, University of MarburgMarburgGermany
| | - Meritxell Canals
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen's Medical Centre, University of NottinghamNottinghamUnited Kingdom
- Centre of Membrane Protein and Receptors, Universities of Birmingham and NottinghamMidlandsUnited Kingdom
| | - Peter Kolb
- Department of Pharmaceutical Chemistry, University of MarburgMarburgGermany
| | - Moritz Bünemann
- Department of Pharmacology and Clinical Pharmacy, University of MarburgMarburgGermany
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Tauber M, Ben-Chaim Y. Functional consequences of a rare human serotonergic 5-HT 1A receptor variant. Front Pharmacol 2023; 14:1270726. [PMID: 37795037 PMCID: PMC10547147 DOI: 10.3389/fphar.2023.1270726] [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: 08/01/2023] [Accepted: 09/08/2023] [Indexed: 10/06/2023] Open
Abstract
Serotonin (5-HT) plays a central role in various brain functions via the activation of a family of receptors, most of them G protein coupled receptors (GPCRs). 5-HT1A receptor, the most abundant 5-HT receptors, was implicated in many brain dysfunctions and is a major target for drug discovery. Several genetic polymorphisms within the 5-HT1A receptor gene were identified and linked to different conditions, including anxiety and depression. Here, we used Xenopus oocytes to examine the effects of one of the functional polymorphism, Arg220Leu, on the function of the receptor. We found that the mutated receptor shows normal activation of G protein and normal 5-HT binding. On the other hand, the mutated receptor shows impaired desensitization, probably due to impairment in activation of β arrestin-dependent pathway. Furthermore, while the 5-HT1A receptor was shown to exhibit voltage dependent activation by serotonin and by buspirone, the mutated receptor was voltage-independent. Our results suggest a pronounced effect of the mutation on the function of the 5-HT1A receptor and add to our understanding of the molecular mechanism of its voltage dependence. Moreover, the findings of this study may suggest a functional explanation for the possible link between this variant and brain pathologies.
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Affiliation(s)
| | - Yair Ben-Chaim
- Department of Natural Sciences, The Open University of Israel, Ra’anana, Israel
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Raz N, Eyal AM, Berneman Zeitouni D, Hen-Shoval D, Davidson EM, Danieli A, Tauber M, Ben-Chaim Y. SELECTED CANNABIS TERPENES SYNERGIZE WITH THC TO PRODUCE INCREASED CB1 RECEPTOR ACTIVATION. Biochem Pharmacol 2023; 212:115548. [PMID: 37084981 DOI: 10.1016/j.bcp.2023.115548] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 04/05/2023] [Accepted: 04/05/2023] [Indexed: 04/23/2023]
Abstract
The cannabis plant exerts its pharmaceutical activity primarily by the binding of cannabinoids to two G protein-coupled cannabinoid receptors, CB1 and CB2. The role that cannabis terpenes play in this activation has been considered and debated repeatedly, based on only limited experimental results. In the current study we used a controlled in-vitro heterologous expression system to quantify the activation of CB1 receptors by sixteen cannabis terpenes individually, by tetrahydrocannabinol (THC) alone and by THC-terpenes mixtures. The results demonstrate that all terpenes, when tested individually, activate CB1 receptors, at about 10-50% of the activation by THC alone. The combination of some of these terpenes with THC significantly increases the activity of the CB1 receptor, compared to THC alone. In some cases, several fold. Importantly, this amplification is evident at terpene to THC ratios similar to those in the cannabis plant, which reflect very low terpene concentrations. For some terpenes, the activation obtained by THC- terpene mixtures is notably greater than the sum of the activations by the individual components, suggesting a synergistic effect. Our results strongly support a modulatory effect of some of the terpenes on the interaction between THC and the CB1 receptor. As the most effective terpenes are not necessarily the most abundant ones in the cannabis plant, reaching "whole plant" or "full spectrum" composition is not necessarily an advantage. For enhanced therapeutic effects, desired compositions are attainable by enriching extracts with selected terpenes. These compositions adjust the treatment for various desired medicinal and personal needs.
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Affiliation(s)
- Noa Raz
- Bazelet Medical Cannabis Group, Or Akiva, Israel
| | | | | | | | - Elyad M Davidson
- Department of Anesthesiology, CCM and Pain Relief, Hadassah Hebrew University Hospital Jerusalem, Israel
| | - Aviel Danieli
- Department of Natural and Life Sciences, The Open University of Israel, Ra'anana, Israel
| | - Merav Tauber
- Department of Natural and Life Sciences, The Open University of Israel, Ra'anana, Israel
| | - Yair Ben-Chaim
- Department of Natural and Life Sciences, The Open University of Israel, Ra'anana, Israel.
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Shpakov AO. Allosteric Regulation of G-Protein-Coupled Receptors: From Diversity of Molecular Mechanisms to Multiple Allosteric Sites and Their Ligands. Int J Mol Sci 2023; 24:6187. [PMID: 37047169 PMCID: PMC10094638 DOI: 10.3390/ijms24076187] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/21/2023] [Accepted: 03/23/2023] [Indexed: 03/29/2023] Open
Abstract
Allosteric regulation is critical for the functioning of G protein-coupled receptors (GPCRs) and their signaling pathways. Endogenous allosteric regulators of GPCRs are simple ions, various biomolecules, and protein components of GPCR signaling (G proteins and β-arrestins). The stability and functional activity of GPCR complexes is also due to multicenter allosteric interactions between protomers. The complexity of allosteric effects caused by numerous regulators differing in structure, availability, and mechanisms of action predetermines the multiplicity and different topology of allosteric sites in GPCRs. These sites can be localized in extracellular loops; inside the transmembrane tunnel and in its upper and lower vestibules; in cytoplasmic loops; and on the outer, membrane-contacting surface of the transmembrane domain. They are involved in the regulation of basal and orthosteric agonist-stimulated receptor activity, biased agonism, GPCR-complex formation, and endocytosis. They are targets for a large number of synthetic allosteric regulators and modulators, including those constructed using molecular docking. The review is devoted to the principles and mechanisms of GPCRs allosteric regulation, the multiplicity of allosteric sites and their topology, and the endogenous and synthetic allosteric regulators, including autoantibodies and pepducins. The allosteric regulation of chemokine receptors, proteinase-activated receptors, thyroid-stimulating and luteinizing hormone receptors, and beta-adrenergic receptors are described in more detail.
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Affiliation(s)
- Alexander O Shpakov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, 194223 St. Petersburg, Russia
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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: 2.0] [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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Goldberger E, Tauber M, Ben-Chaim Y. Voltage dependence of the cannabinoid CB1 receptor. Front Pharmacol 2022; 13:1022275. [PMID: 36304142 PMCID: PMC9592857 DOI: 10.3389/fphar.2022.1022275] [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: 08/18/2022] [Accepted: 09/21/2022] [Indexed: 11/13/2022] Open
Abstract
Cannabinoids produce their characteristic effects mainly by binding to two types of G-protein coupled receptors (GPCRs), the CB1 and CB2 cannabinoid receptors. The CB1 receptor is the main cannabinoid receptor in the central nervous system, and it participates in many brain functions. Recent studies showed that membrane potential may serve as a novel modulatory modality of many GPCRs. Here, we used Xenopus oocytes as an expression system to examine whether membrane potential modulates the activity of the CB1 receptor. We found that the potencies of the endocannabinoid 2-AG and the phytocannabinoid THC in activating the receptor are voltage dependent; depolarization enhanced the potency of these agonists and decreased their dissociation from the receptor. This voltage dependence appears to be agonist dependent as the potency of the endocannabinoid anandamide (AEA) was voltage independent. The finding of this agonist-specific modulatory factor for the CB1 receptor may contribute to our future understanding of various physiological functions mediated by the endocannabinoid system.
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