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Boutonnet M, Carpena C, Bouquier N, Chastagnier Y, Font-Ingles J, Moutin E, Tricoire L, Chemin J, Perroy J. Voltage tunes mGlu 5 receptor function, impacting synaptic transmission. Br J Pharmacol 2024; 181:1793-1811. [PMID: 38369690 DOI: 10.1111/bph.16317] [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: 09/07/2023] [Revised: 12/08/2023] [Accepted: 12/29/2023] [Indexed: 02/20/2024] Open
Abstract
BACKGROUND AND PURPOSE Voltage sensitivity is a common feature of many membrane proteins, including some G-protein coupled receptors (GPCRs). However, the functional consequences of voltage sensitivity in GPCRs are not well understood. EXPERIMENTAL APPROACH In this study, we investigated the voltage sensitivity of the post-synaptic metabotropic glutamate receptor mGlu5 and its impact on synaptic transmission. Using biosensors and electrophysiological recordings in non-excitable HEK293T cells or neurons. KEY RESULTS We found that mGlu5 receptor function is optimal at resting membrane potentials. We observed that membrane depolarization significantly reduced mGlu5 receptor activation, Gq-PLC/PKC stimulation, Ca2+ release and mGlu5 receptor-gated currents through transient receptor potential canonical, TRPC6, channels or glutamate ionotropic NMDA receptors. Notably, we report a previously unknown activity of the NMDA receptor at the resting potential of neurons, enabled by mGlu5. CONCLUSIONS AND IMPLICATIONS Our findings suggest that mGlu5 receptor activity is directly regulated by membrane voltage which may have a significant impact on synaptic processes and pathophysiological functions.
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Affiliation(s)
- Marin Boutonnet
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Camille Carpena
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
| | | | - Yan Chastagnier
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Joan Font-Ingles
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
- SpliceBio, Barcelona, Spain
| | - Enora Moutin
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Ludovic Tricoire
- Neuroscience Paris Seine, Institut de biologie Paris Seine, Sorbonne universite, CNRS, INSERM, Paris, France
| | - Jean Chemin
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Julie Perroy
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
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2
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Tauber M, Ben-Chaim Y. Voltage Sensors Embedded in G Protein-Coupled Receptors. Int J Mol Sci 2024; 25:5295. [PMID: 38791333 PMCID: PMC11120775 DOI: 10.3390/ijms25105295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Revised: 05/08/2024] [Accepted: 05/09/2024] [Indexed: 05/26/2024] Open
Abstract
Some signaling processes mediated by G protein-coupled receptors (GPCRs) are modulated by membrane potential. In recent years, increasing evidence that GPCRs are intrinsically voltage-dependent has accumulated. A recent publication challenged the view that voltage sensors are embedded in muscarinic receptors. Herein, we briefly discuss the evidence that supports the notion that GPCRs themselves are voltage-sensitive proteins and an alternative mechanism that suggests that voltage-gated sodium channels are the voltage-sensing molecules involved in such processes.
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Affiliation(s)
| | - Yair Ben-Chaim
- Department of Natural Sciences, The Open University of Israel, Ra’anana 4353701, Israel
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3
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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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4
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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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5
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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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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: 5] [Impact Index Per Article: 2.5] [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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Tauber M, Ben Chaim Y. The activity of the serotonergic 5-HT 1A receptor is modulated by voltage and sodium levels. J Biol Chem 2022; 298:101978. [PMID: 35469922 PMCID: PMC9136116 DOI: 10.1016/j.jbc.2022.101978] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 04/16/2022] [Accepted: 04/20/2022] [Indexed: 11/28/2022] Open
Abstract
G protein–coupled receptors are known to play a key role in many cellular signal transduction processes, including those mediating serotonergic signaling in the nervous system. Several factors have been shown to regulate the activity of these receptors, including membrane potential and the concentration of sodium ions. Whether voltage and sodium regulate the activity of serotonergic receptors is unknown. Here, we used Xenopus oocytes as an expression system to examine the effects of voltage and of sodium ions on the potency of one subtype of serotonin (5-hydroxytryptamine [5-HT]) receptor, the 5-HT1A receptor. We found that the potency of 5-HT in activating the receptor is voltage dependent and that it is higher at resting potential than under depolarized conditions. Furthermore, we found that removal of extracellular Na+ resulted in a decrease of 5-HT potency toward the 5-HT1A receptor and that a conserved aspartate in transmembrane domain 2 is crucial for this effect. Our results suggest that this allosteric effect of Na+ does not underlie the voltage dependence of this receptor. We propose that the characterization of modulatory factors that regulate this receptor may contribute to our future understanding of various physiological functions mediated by serotonergic transmission.
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Affiliation(s)
- 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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8
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Ozkan AD, Gettas T, Sogata A, Phaychanpheng W, Zhou M, Lacroix JJ. Mechanical and chemical activation of GPR68 probed with a genetically encoded fluorescent reporter. J Cell Sci 2021; 134:271846. [PMID: 34322699 DOI: 10.1242/jcs.255455] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 07/17/2021] [Indexed: 12/24/2022] Open
Abstract
G-protein-coupled receptor (GPCR) 68 (GPR68, or OGR1) couples extracellular acidifications and mechanical stimuli to G-protein signaling and plays important roles in vascular physiology, neuroplasticity and cancer progression. Inspired by previous GPCR-based reporters, here, we inserted a cyclic permuted fluorescent protein into the third intracellular loop of GPR68 to create a genetically encoded fluorescent reporter of GPR68 activation we call 'iGlow'. iGlow responds to known physiological GPR68 activators such as fluid shear stress and extracellular acidifications. In addition, iGlow responds to Ogerin, a synthetic GPR68-selective agonist, but not to a non-active Ogerin analog, showing the specificity of iGlow-mediated fluorescence signals. Flow-induced iGlow activation is not eliminated by pharmacological modulation of downstream G-protein signaling, disruption of actin filaments or application of GsMTx4, an inhibitor of certain mechanosensitive ion channels activated by membrane stretch. Deletion of the conserved helix 8, proposed to mediate mechanosensitivity in certain GPCRs, does not eliminate flow-induced iGlow activation. iGlow could be useful to investigate the contribution of GPR68-dependent signaling in health and disease.
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Affiliation(s)
- Alper D Ozkan
- Graduate College of Biomedical Sciences, Western University of Health Sciences, 309 E. Second St, Pomona, CA 91766, USA
| | - Tina Gettas
- Graduate College of Biomedical Sciences, Western University of Health Sciences, 309 E. Second St, Pomona, CA 91766, USA
| | - Audrey Sogata
- Chino Hills High School, 16150 Pomona Rincon Rd, Chino Hills, CA 91709, USA
| | - Wynn Phaychanpheng
- Chino Hills High School, 16150 Pomona Rincon Rd, Chino Hills, CA 91709, USA
| | - Miou Zhou
- Graduate College of Biomedical Sciences, Western University of Health Sciences, 309 E. Second St, Pomona, CA 91766, USA
| | - Jérôme J Lacroix
- Graduate College of Biomedical Sciences, Western University of Health Sciences, 309 E. Second St, Pomona, CA 91766, USA
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9
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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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10
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Sodium ions allosterically modulate the M2 muscarinic receptor. Sci Rep 2020; 10:11177. [PMID: 32636499 PMCID: PMC7341750 DOI: 10.1038/s41598-020-68133-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 06/15/2020] [Indexed: 11/08/2022] Open
Abstract
G protein coupled receptors (GPCRs) play a key role in the vast majority of cellular signal transduction processes. Previous experimental evidence has shown that sodium ion (Na+) allosterically modulate several class A GPCRs and theoretical studies suggested that the same also holds true for muscarinic receptors. Here we examined, using Xenopus oocytes as an expression system, the effect of Na+ on a prototypical GPCR, the M2 muscarinic receptor (M2R). We found that removal of extracellular Na+ resulted in a decrease in the potency of ACh toward the M2R and that a conserved aspartate in transmembrane domain 2 is crucial for this effect. We further show that this allosteric effect of Na+ does not underlie the voltage-dependence of this receptor.
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11
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Ruland JG, Kirchhofer SB, Klindert S, Bailey CP, Bünemann M. Voltage modulates the effect of μ-receptor activation in a ligand-dependent manner. Br J Pharmacol 2020; 177:3489-3504. [PMID: 32297669 PMCID: PMC7348086 DOI: 10.1111/bph.15070] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 03/16/2020] [Accepted: 03/30/2020] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND AND PURPOSE Various GPCRs have been described as being modulated in a voltage-dependent manner. Opioid analgesics act via activation of μ receptors in various neurons. As neurons are exposed to large changes in membrane potential, we were interested in studying the effects of depolarization on μ receptor signalling. EXPERIMENTAL APPROACH We investigated potential voltage sensitivity of μ receptors in heterologous expression systems (HEK293T cells) using electrophysiology in combination with Förster resonance energy transfer-based assays. Depolarization-induced changes in signalling were also tested in physiological rat tissue containing locus coeruleus neurons. We applied depolarization steps across the physiological range of membrane potentials. KEY RESULTS Studying μ receptor function and signalling in cells, we discovered that morphine-induced signalling was strongly dependent on the membrane potential (VM ). This became apparent at the level of G-protein activation, G-protein coupled inwardly rectifying potassium channel (Kir 3.X) currents and binding of GPCR kinases and arrestin3 to μ receptors by a robust increase in signalling upon membrane depolarization. The pronounced voltage sensitivity of morphine-induced μ receptor activation was also observed at the level of Kir 3.X currents in rat locus coeruleus neurons. The efficacy of peptide ligands to activate μ receptors was not (Met-enkephalin) or only moderately ([D-Ala2 , N-Me-Phe4 , Gly5 -ol]-enkephalin) enhanced upon depolarization. In contrast, depolarization reduced the ability of the analgesic fentanyl to activate μ receptors. CONCLUSION AND IMPLICATIONS Our results indicate a strong ligand-dependent modulation of μ receptor activity by the membrane potential, suggesting preferential activity of morphine in neurons with high neuronal activity.
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Affiliation(s)
- Julia G Ruland
- Department of Pharmacology and Clinical Pharmacy, Philipps-University, Marburg, Germany
| | - Sina B Kirchhofer
- Department of Pharmacology and Clinical Pharmacy, Philipps-University, Marburg, Germany
| | - Sebastian Klindert
- Department of Pharmacology and Clinical Pharmacy, Philipps-University, Marburg, Germany.,Department of Pharmacy and Pharmacology, University of Bath, Bath, UK
| | - Chris P Bailey
- Department of Pharmacy and Pharmacology, University of Bath, Bath, UK
| | - Moritz Bünemann
- Department of Pharmacology and Clinical Pharmacy, Philipps-University, Marburg, Germany
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12
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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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13
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Helix 8 is the essential structural motif of mechanosensitive GPCRs. Nat Commun 2019; 10:5784. [PMID: 31857598 PMCID: PMC6923424 DOI: 10.1038/s41467-019-13722-0] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 11/19/2019] [Indexed: 12/16/2022] Open
Abstract
G-protein coupled receptors (GPCRs) are versatile cellular sensors for chemical stimuli, but also serve as mechanosensors involved in various (patho)physiological settings like vascular regulation, cardiac hypertrophy and preeclampsia. However, the molecular mechanisms underlying mechanically induced GPCR activation have remained elusive. Here we show that mechanosensitive histamine H1 receptors (H1Rs) are endothelial sensors of fluid shear stress and contribute to flow-induced vasodilation. At the molecular level, we observe that H1Rs undergo stimulus-specific patterns of conformational changes suggesting that mechanical forces and agonists induce distinct active receptor conformations. GPCRs lacking C-terminal helix 8 (H8) are not mechanosensitive, and transfer of H8 to non-responsive GPCRs confers, while removal of H8 precludes, mechanosensitivity. Moreover, disrupting H8 structural integrity by amino acid exchanges impairs mechanosensitivity. Altogether, H8 is the essential structural motif endowing GPCRs with mechanosensitivity. These findings provide a mechanistic basis for a better understanding of the roles of mechanosensitive GPCRs in (patho)physiology. GPCRs are versatile cellular sensors for chemical stimuli but the molecular mechanisms underlying mechanically induced GPCR activation have remained elusive. Here authors identify the C-terminal helix 8 (H8) as the essential structural motif endowing H1R and other GPCRs with mechanosensitivity.
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14
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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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15
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Zarzycka B, Zaidi SA, Roth BL, Katritch V. Harnessing Ion-Binding Sites for GPCR Pharmacology. Pharmacol Rev 2019; 71:571-595. [PMID: 31551350 PMCID: PMC6782022 DOI: 10.1124/pr.119.017863] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Endogenous ions play important roles in the function and pharmacology of G-protein coupled receptors (GPCRs). Historically the evidence for ionic modulation of GPCR function dates to 1973 with studies of opioid receptors, where it was demonstrated that physiologic concentrations of sodium allosterically attenuated agonist binding. This Na+-selective effect was distinct from effects of other monovalent and divalent cations, with the latter usually counteracting sodium's negative allosteric modulation of binding. Since then, numerous studies documenting the effects of mono- and divalent ions on GPCR function have been published. While ions can act selectively and nonselectively at many sites in different receptors, the discovery of the conserved sodium ion site in class A GPCR structures in 2012 revealed the unique nature of Na+ site, which has emerged as a near-universal site for allosteric modulation of class A GPCR structure and function. In this review, we synthesize and highlight recent advances in the functional, biophysical, and structural characterization of ions bound to GPCRs. Taken together, these findings provide a molecular understanding of the unique roles of Na+ and other ions as GPCR allosteric modulators. We will also discuss how this knowledge can be applied to the redesign of receptors and ligand probes for desired functional and pharmacological profiles. SIGNIFICANCE STATEMENT: The function and pharmacology of GPCRs strongly depend on the presence of mono and divalent ions in experimental assays and in living organisms. Recent insights into the molecular mechanism of this ion-dependent allosterism from structural, biophysical, biochemical, and computational studies provide quantitative understandings of the pharmacological effects of drugs in vitro and in vivo and open new avenues for the rational design of chemical probes and drug candidates with improved properties.
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Affiliation(s)
- Barbara Zarzycka
- Departments of Biological Sciences (B.Z., S.A.Z., V.K.) and Chemistry (V.K.), Bridge Institute, Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, California; and Department of Pharmacology (B.L.R.) and Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy (B.L.R.), University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Saheem A Zaidi
- Departments of Biological Sciences (B.Z., S.A.Z., V.K.) and Chemistry (V.K.), Bridge Institute, Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, California; and Department of Pharmacology (B.L.R.) and Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy (B.L.R.), University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Bryan L Roth
- Departments of Biological Sciences (B.Z., S.A.Z., V.K.) and Chemistry (V.K.), Bridge Institute, Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, California; and Department of Pharmacology (B.L.R.) and Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy (B.L.R.), University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Vsevolod Katritch
- Departments of Biological Sciences (B.Z., S.A.Z., V.K.) and Chemistry (V.K.), Bridge Institute, Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, California; and Department of Pharmacology (B.L.R.) and Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy (B.L.R.), University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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16
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Membrane potential changes occurring upon acidification influence the binding of small-molecule inhibitors to ASIC1a. Neuropharmacology 2019; 148:366-376. [DOI: 10.1016/j.neuropharm.2019.01.033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 01/10/2019] [Accepted: 01/31/2019] [Indexed: 12/23/2022]
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17
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Zhang XC, Zhou Y, Cao C. Proton transfer during class-A GPCR activation: do the CWxP motif and the membrane potential act in concert? BIOPHYSICS REPORTS 2018. [DOI: 10.1007/s41048-018-0056-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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18
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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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19
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Zhang XC, Liu M, Lu G, Heng J. Thermodynamic secrets of multidrug resistance: A new take on transport mechanisms of secondary active antiporters. Protein Sci 2017; 27:595-613. [PMID: 29193407 DOI: 10.1002/pro.3355] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 11/20/2017] [Accepted: 11/21/2017] [Indexed: 12/17/2022]
Abstract
Multidrug resistance (MDR) presents a growing challenge to global public health. Drug extrusion transporters play a critical part in MDR; thus, their mechanisms of substrate recognition are being studied in great detail. In this work, we review common structural features of key transporters involved in MDR. Based on our membrane potential-driving hypothesis, we propose a general energy-coupling mechanism for secondary-active antiporters. This putative mechanism provides a common framework for understanding poly-specificity of most-if not all-MDR transporters.
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Affiliation(s)
- Xuejun C Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, 100101, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Min Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, 100101, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Guangyuan Lu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, 100101, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jie Heng
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, 100101, China
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20
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Hoppe A, Marti-Solano M, Drabek M, Bünemann M, Kolb P, Rinne A. The allosteric site regulates the voltage sensitivity of muscarinic receptors. Cell Signal 2017; 42:114-126. [PMID: 29056499 DOI: 10.1016/j.cellsig.2017.10.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 09/28/2017] [Accepted: 10/19/2017] [Indexed: 11/18/2022]
Abstract
Muscarinic receptors (M-Rs) for acetylcholine (ACh) belong to the class A of G protein-coupled receptors. M-Rs are activated by orthosteric agonists that bind to a specific site buried in the M-R transmembrane helix bundle. In the active conformation, receptor function can be modulated either by allosteric modulators, which bind to the extracellular receptor surface or by the membrane potential via an unknown mechanism. Here, we compared the modulation of M1-Rs and M3-Rs induced by changes in voltage to their allosteric modulation by chemical compounds. We quantified changes in receptor signaling in single HEK 293 cells with a FRET biosensor for the Gq protein cycle. In the presence of ACh, M1-R signaling was potentiated by voltage, similarly to positive allosteric modulation by benzyl quinolone carboxylic acid. Conversely, signaling of M3-R was attenuated by voltage or the negative allosteric modulator gallamine. Because the orthosteric site is highly conserved among M-Rs, but allosteric sites vary, we constructed "allosteric site" M3/M1-R chimeras and analyzed their voltage dependencies. Exchanging the entire allosteric sites eliminated the voltage sensitivity of ACh responses for both receptors, but did not affect their modulation by allosteric compounds. Furthermore, a point mutation in M3-Rs caused functional uncoupling of the allosteric and orthosteric sites and abolished voltage dependence. Molecular dynamics simulations of the receptor variants indicated a subtype-specific crosstalk between both sites, involving the conserved tyrosine lid structure of the orthosteric site. This molecular crosstalk leads to receptor subtype-specific voltage effects.
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Affiliation(s)
- Anika Hoppe
- Department of Cardiovascular Physiology, Ruhr-University Bochum, Universitätsstr. 150, 44780 Bochum, Germany
| | - Maria Marti-Solano
- Department of Pharmaceutical Chemistry, Philipps-University Marburg, Marbacher Weg 6-10, 35032 Marburg, Germany
| | - Matthäus Drabek
- Department of Pharmaceutical Chemistry, Philipps-University Marburg, Marbacher Weg 6-10, 35032 Marburg, Germany
| | - Moritz Bünemann
- Department of Pharmacology and Clinical Pharmacy, Philipps-University Marburg, Karl-von-Frisch-Str. 1, 35043 Marburg, Germany
| | - Peter Kolb
- Department of Pharmaceutical Chemistry, Philipps-University Marburg, Marbacher Weg 6-10, 35032 Marburg, Germany
| | - Andreas Rinne
- Department of Cardiovascular Physiology, Ruhr-University Bochum, Universitätsstr. 150, 44780 Bochum, Germany.
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21
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Storch U, Straub J, Erdogmus S, Gudermann T, Mederos Y Schnitzler M. Dynamic monitoring of G i/o-protein-mediated decreases of intracellular cAMP by FRET-based Epac sensors. Pflugers Arch 2017; 469:725-737. [PMID: 28386636 PMCID: PMC5438440 DOI: 10.1007/s00424-017-1975-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 03/25/2017] [Accepted: 03/30/2017] [Indexed: 01/17/2023]
Abstract
Analysis of G-protein-coupled receptor (GPCR) signaling, in particular of the second messenger cAMP that is tightly controlled by Gs- and Gi/o-proteins, is a central issue in biomedical research. The classical biochemical method to monitor increases in intracellular cAMP concentrations consists of a radioactive multicellular assay, which is well established, highly sensitive, and reproducible, but precludes continuous spatial and temporal assessment of cAMP levels in single living cells. For this purpose, Förster resonance energy transfer (FRET)-based Epac cAMP sensors are well suitable. So far, the latter sensors have been employed to monitor Gs-induced cAMP increases and it has remained elusive whether Epac sensors can reliably detect decreased intracellular cAMP levels as well. In this study, we systematically optimize experimental strategies employing FRET-based cAMP sensors to monitor Gi/o-mediated cAMP reductions. FRET experiments with adrenergic α2A or μ opioid receptors and a set of different Epac sensors allowed for time-resolved, valid, and reliable detection of cAMP level decreases upon Gi/o-coupled receptor activation in single living cells, and this effect can be reversed by selective receptor antagonists. Moreover, pre-treatment with forskolin or 3-isobutyl-1-methylxanthine (IBMX) to artificially increase basal cAMP levels was not required to monitor Gi/o-coupled receptor activation. Thus, using FRET-based cAMP sensors is of major advantage when compared to classical biochemical and multi-cellular assays.
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Affiliation(s)
- Ursula Storch
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig Maximilians University of Munich, Goethestr. 33, 80336, Munich, Germany
| | - Julie Straub
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig Maximilians University of Munich, Goethestr. 33, 80336, Munich, Germany
| | - Serap Erdogmus
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig Maximilians University of Munich, Goethestr. 33, 80336, Munich, Germany
| | - Thomas Gudermann
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig Maximilians University of Munich, Goethestr. 33, 80336, Munich, Germany.,DZHK (German Centre for Cardiovascular Research), Munich Heart Alliance, Munich, Germany.,Comprehensive Pneumology Center Munich (CPC-M), German Center for Lung Research, Munich, Germany
| | - Michael Mederos Y Schnitzler
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig Maximilians University of Munich, Goethestr. 33, 80336, Munich, Germany. .,DZHK (German Centre for Cardiovascular Research), Munich Heart Alliance, Munich, Germany.
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22
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Zhang XC, Zhou Y, Cao C. Thermodynamics of GPCR activation. BIOPHYSICS REPORTS 2016; 1:115-119. [PMID: 27340689 PMCID: PMC4871901 DOI: 10.1007/s41048-016-0017-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 01/06/2016] [Indexed: 12/30/2022] Open
Affiliation(s)
- Xuejun C Zhang
- National Laboratory of Macromolecules, National Center of Protein Science-Beijing, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
| | - Ye Zhou
- National Laboratory of Macromolecules, National Center of Protein Science-Beijing, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
| | - Can Cao
- National Laboratory of Macromolecules, National Center of Protein Science-Beijing, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
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