1
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Demby A, Zaccolo M. Investigating G-protein coupled receptor signalling with light-emitting biosensors. Front Physiol 2024; 14:1310197. [PMID: 38260094 PMCID: PMC10801095 DOI: 10.3389/fphys.2023.1310197] [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: 10/09/2023] [Accepted: 12/19/2023] [Indexed: 01/24/2024] Open
Abstract
G protein-coupled receptors (GPCRs) are the most frequent target of currently approved drugs and play a central role in both physiological and pathophysiological processes. Beyond the canonical understanding of GPCR signal transduction, the importance of receptor conformation, beta-arrestin (β-arr) biased signalling, and signalling from intracellular locations other than the plasma membrane is becoming more apparent, along with the tight spatiotemporal compartmentalisation of downstream signals. Fluorescent and bioluminescent biosensors have played a pivotal role in elucidating GPCR signalling events in live cells. To understand the mechanisms of action of the GPCR-targeted drugs currently available, and to develop new and better GPCR-targeted therapeutics, understanding these novel aspects of GPCR signalling is critical. In this review, we present some of the tools available to interrogate each of these features of GPCR signalling, we illustrate some of the key findings which have been made possible by these tools and we discuss their limitations and possible developments.
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Affiliation(s)
| | - Manuela Zaccolo
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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2
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Sullere S, Kunczt A, McGehee DS. A cholinergic circuit that relieves pain despite opioid tolerance. Neuron 2023; 111:3414-3434.e15. [PMID: 37734381 PMCID: PMC10843525 DOI: 10.1016/j.neuron.2023.08.017] [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: 01/18/2023] [Revised: 04/19/2023] [Accepted: 08/16/2023] [Indexed: 09/23/2023]
Abstract
Chronic pain is a tremendous burden for afflicted individuals and society. Although opioids effectively relieve pain, significant adverse outcomes limit their utility and efficacy. To investigate alternate pain control mechanisms, we explored cholinergic signaling in the ventrolateral periaqueductal gray (vlPAG), a critical nexus for descending pain modulation. Biosensor assays revealed that pain states decreased acetylcholine release in vlPAG. Activation of cholinergic projections from the pedunculopontine tegmentum to vlPAG relieved pain, even in opioid-tolerant conditions, through ⍺7 nicotinic acetylcholine receptors (nAChRs). Activating ⍺7 nAChRs with agonists or stimulating endogenous acetylcholine inhibited vlPAG neuronal activity through Ca2+ and peroxisome proliferator-activated receptor α (PPAR⍺)-dependent signaling. In vivo 2-photon imaging revealed that chronic pain induces aberrant excitability of vlPAG neuronal ensembles and that ⍺7 nAChR-mediated inhibition of these cells relieves pain, even after opioid tolerance. Finally, pain relief through these cholinergic mechanisms was not associated with tolerance, reward, or withdrawal symptoms, highlighting its potential clinical relevance.
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Affiliation(s)
- Shivang Sullere
- Committee on Neurobiology, University of Chicago, Chicago, IL 60637, USA
| | - Alissa Kunczt
- Department of Anesthesia and Critical Care, University of Chicago, Chicago, IL 60637, USA
| | - Daniel S McGehee
- Committee on Neurobiology, University of Chicago, Chicago, IL 60637, USA; Department of Anesthesia and Critical Care, University of Chicago, Chicago, IL 60637, USA.
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3
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Heinz CS, Bermudez M, Jaiswal N, Große C, Kauk M, Hoffmann C, Holzgrabe U. Hybridization into a Bitopic Ligand Increased Muscarinic Receptor Activation for Isopilocarpine but Not for Pilocarpine Derivatives. JOURNAL OF NATURAL PRODUCTS 2023; 86:869-881. [PMID: 37042802 DOI: 10.1021/acs.jnatprod.2c01079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Pilocarpine (1), a secondary metabolite of several Pilocarpus species, is a therapeutically used partial agonist of muscarinic acetylcholine receptors (mAChRs). The available pharmacological data and structure-activity relationships do not provide comparable data for all five receptor subtypes. In this study, pilocarpine (1), its epimer isopilocarpine (2), racemic analogues pilosinine (3) and desmethyl pilosinine (4), and the respective hybrid ligands with a naphmethonium fragment (5-C6 to 8-C6) were synthesized and analyzed in mini-G nano-BRET assays at the five mAChRs. In line with earlier studies, pilocarpine was the most active compound among the orthosteric ligands 1-4. Computational docking of pilocarpine and isopilocarpine to the active M2 receptor suggests that the trans-configuration of isopilocarpine leads to a loss of the hydrogen bond from the lactone carbonyl to N6.52, explaining the lower activity of isopilocarpine. Hybrid formation of pilocarpine (1) and isopilocarpine (2) led to an inverted activity rank, with the trans-configured isopilocarpine hybrid (6-C6) being more active. The hydrogen bond of interest is formed by the isopilocarpine hybrid (6-C6) but not by the pilocarpine hybrid (5-C6). Hybridization thus leads to a modified binding mode of the orthosteric moiety, as the binding mode of the hybrid is dominated by the high-affinity allosteric moiety.
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Affiliation(s)
- Christine S Heinz
- Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Marcel Bermudez
- Institute of Pharmaceutical and Medicinal Chemistry, Westfälische Wilhelms-Universität, Corrensstraße 48, 48149 Muenster, Germany
| | - Natasha Jaiswal
- Institute for Molecular Cell Biology, CMB-Center for Molecular Biomedicine, University Hospital Jena, Friedrich-Schiller University Jena, Hans-Knöll-Straße 2, 07745 Jena, Germany
| | - Carolin Große
- Institute for Molecular Cell Biology, CMB-Center for Molecular Biomedicine, University Hospital Jena, Friedrich-Schiller University Jena, Hans-Knöll-Straße 2, 07745 Jena, Germany
| | - Michael Kauk
- Institute for Molecular Cell Biology, CMB-Center for Molecular Biomedicine, University Hospital Jena, Friedrich-Schiller University Jena, Hans-Knöll-Straße 2, 07745 Jena, Germany
| | - Carsten Hoffmann
- Institute for Molecular Cell Biology, CMB-Center for Molecular Biomedicine, University Hospital Jena, Friedrich-Schiller University Jena, Hans-Knöll-Straße 2, 07745 Jena, Germany
| | - Ulrike Holzgrabe
- Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
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4
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Matera C, Kauk M, Cirillo D, Maspero M, Papotto C, Volpato D, Holzgrabe U, De Amici M, Hoffmann C, Dallanoce C. Novel Xanomeline-Containing Bitopic Ligands of Muscarinic Acetylcholine Receptors: Design, Synthesis and FRET Investigation. Molecules 2023; 28:molecules28052407. [PMID: 36903650 PMCID: PMC10005175 DOI: 10.3390/molecules28052407] [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: 01/30/2023] [Revised: 03/01/2023] [Accepted: 03/03/2023] [Indexed: 03/08/2023] Open
Abstract
In the last few years, fluorescence resonance energy transfer (FRET) receptor sensors have contributed to the understanding of GPCR ligand binding and functional activation. FRET sensors based on muscarinic acetylcholine receptors (mAChRs) have been employed to study dual-steric ligands, allowing for the detection of different kinetics and distinguishing between partial, full, and super agonism. Herein, we report the synthesis of the two series of bitopic ligands, 12-Cn and 13-Cn, and their pharmacological investigation at the M1, M2, M4, and M5 FRET-based receptor sensors. The hybrids were prepared by merging the pharmacophoric moieties of the M1/M4-preferring orthosteric agonist Xanomeline 10 and the M1-selective positive allosteric modulator 77-LH-28-1 (1-[3-(4-butyl-1-piperidinyl)propyl]-3,4-dihydro-2(1H)-quinolinone) 11. The two pharmacophores were connected through alkylene chains of different lengths (C3, C5, C7, and C9). Analyzing the FRET responses, the tertiary amine compounds 12-C5, 12-C7, and 12-C9 evidenced a selective activation of M1 mAChRs, while the methyl tetrahydropyridinium salts 13-C5, 13-C7, and 13-C9 showed a degree of selectivity for M1 and M4 mAChRs. Moreover, whereas hybrids 12-Cn showed an almost linear response at the M1 subtype, hybrids 13-Cn evidenced a bell-shaped activation response. This different activation pattern suggests that the positive charge anchoring the compound 13-Cn to the orthosteric site ensues a degree of receptor activation depending on the linker length, which induces a graded conformational interference with the binding pocket closure. These bitopic derivatives represent novel pharmacological tools for a better understanding of ligand-receptor interactions at a molecular level.
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Affiliation(s)
- Carlo Matera
- Department of Pharmaceutical Sciences, Medicinal Chemistry Section “Pietro Pratesi”, University of Milan, Via L. Mangiagalli 25, 20133 Milan, Italy
| | - Michael Kauk
- Institute for Molecular Cell Biology, Center for Molecular Biomedicine, University Hospital Jena, Friedrich Schiller University Jena, Hans Knoell Str. 2, 07745 Jena, Germany
| | - Davide Cirillo
- Department of Pharmaceutical Sciences, Medicinal Chemistry Section “Pietro Pratesi”, University of Milan, Via L. Mangiagalli 25, 20133 Milan, Italy
| | - Marco Maspero
- Department of Pharmaceutical Sciences, Medicinal Chemistry Section “Pietro Pratesi”, University of Milan, Via L. Mangiagalli 25, 20133 Milan, Italy
| | - Claudio Papotto
- Department of Pharmaceutical Sciences, Medicinal Chemistry Section “Pietro Pratesi”, University of Milan, Via L. Mangiagalli 25, 20133 Milan, Italy
| | - Daniela Volpato
- Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy and Food Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Ulrike Holzgrabe
- Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy and Food Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Marco De Amici
- Department of Pharmaceutical Sciences, Medicinal Chemistry Section “Pietro Pratesi”, University of Milan, Via L. Mangiagalli 25, 20133 Milan, Italy
| | - Carsten Hoffmann
- Institute for Molecular Cell Biology, Center for Molecular Biomedicine, University Hospital Jena, Friedrich Schiller University Jena, Hans Knoell Str. 2, 07745 Jena, Germany
| | - Clelia Dallanoce
- Department of Pharmaceutical Sciences, Medicinal Chemistry Section “Pietro Pratesi”, University of Milan, Via L. Mangiagalli 25, 20133 Milan, Italy
- Correspondence: ; Tel.: +39-02-503-19327
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5
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Kim H, Baek IY, Seong J. Genetically encoded fluorescent biosensors for GPCR research. Front Cell Dev Biol 2022; 10:1007893. [PMID: 36247000 PMCID: PMC9559200 DOI: 10.3389/fcell.2022.1007893] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 09/09/2022] [Indexed: 11/13/2022] Open
Abstract
G protein-coupled receptors (GPCRs) regulate a wide range of physiological and pathophysiological cellular processes, thus it is important to understand how GPCRs are activated and function in various cellular contexts. In particular, the activation process of GPCRs is dynamically regulated upon various extracellular stimuli, and emerging evidence suggests the subcellular functions of GPCRs at endosomes and other organelles. Therefore, precise monitoring of the GPCR activation process with high spatiotemporal resolution is required to investigate the underlying molecular mechanisms of GPCR functions. In this review, we will introduce genetically encoded fluorescent biosensors that can precisely monitor the real-time GPCR activation process in live cells. The process includes the binding of extracellular GPCR ligands, conformational change of GPCR, recruitment of G proteins or β-arrestin, GPCR internalization and trafficking, and the GPCR-related downstream signaling events. We will introduce fluorescent GPCR biosensors based on a variety of strategies such as fluorescent resonance energy transfer (FRET), bioluminescence resonance energy transfer (BRET), circular permuted fluorescent protein (cpFP), and nanobody. We will discuss the pros and cons of these GPCR biosensors as well as their applications in GPCR research.
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Affiliation(s)
- Hyunbin Kim
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, South Korea
- Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology, Seoul, South Korea
| | - In-Yeop Baek
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, South Korea
- Department of Converging Science and Technology, Kyung Hee University, Seoul, South Korea
| | - Jihye Seong
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, South Korea
- Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology, Seoul, South Korea
- Department of Converging Science and Technology, Kyung Hee University, Seoul, South Korea
- *Correspondence: Jihye Seong,
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6
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Examination of Intracellular GPCR-Mediated Signaling with High Temporal Resolution. Int J Mol Sci 2022; 23:ijms23158516. [PMID: 35955656 PMCID: PMC9369311 DOI: 10.3390/ijms23158516] [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: 07/15/2022] [Revised: 07/28/2022] [Accepted: 07/29/2022] [Indexed: 11/17/2022] Open
Abstract
The GTP-binding protein-coupled receptors (GPCRs) play important roles in physiology and neuronal signaling. More than a thousand genes, excluding the olfactory receptors, have been identified that encode these integral membrane proteins. Their pharmacological and functional properties make them fascinating targets for drug development, since various disease states can be treated and overcome by pharmacologically addressing these receptors and/or their downstream interacting partners. The activation of the GPCRs typically causes transient changes in the intracellular second messenger concentrations as well as in membrane conductance. In contrast to ion channel-mediated electrical signaling which results in spontaneous cellular responses, the GPCR-mediated metabotropic signals operate at a different time scale. Here we have studied the kinetics of two common GPCR-induced signaling pathways: (a) Ca2+ release from intracellular stores and (b) cyclic adenosine monophosphate (cAMP) production. The latter was monitored via the activation of cyclic nucleotide-gated (CNG) ion channels causing Ca2+ influx into the cell. Genetically modified and stably transfected cell lines were established and used in stopped-flow experiments to uncover the individual steps of the reaction cascades. Using two homologous biogenic amine receptors, either coupling to Go/q or Gs proteins, allowed us to determine the time between receptor activation and signal output. With ~350 ms, the release of Ca2+ from intracellular stores was much faster than cAMP-mediated Ca2+ entry through CNG channels (~6 s). The measurements with caged compounds suggest that this difference is due to turnover numbers of the GPCR downstream effectors rather than the different reaction cascades, per se.
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7
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Tjahjono N, Jin Y, Hsu A, Roukes M, Tian L. Letting the little light of mind shine: Advances and future directions in neurochemical detection. Neurosci Res 2022; 179:65-78. [PMID: 34861294 PMCID: PMC9508992 DOI: 10.1016/j.neures.2021.11.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 11/29/2021] [Indexed: 12/12/2022]
Abstract
Synaptic transmission via neurochemical release is the fundamental process that integrates and relays encoded information in the brain to regulate physiological function, cognition, and emotion. To unravel the biochemical, biophysical, and computational mechanisms of signal processing, one needs to precisely measure the neurochemical release dynamics with molecular and cell-type specificity and high resolution. Here we reviewed the development of analytical, electrochemical, and fluorescence imaging approaches to detect neurotransmitter and neuromodulator release. We discussed the advantages and practicality in implementation of each technology for ease-of-use, flexibility for multimodal studies, and challenges for future optimization. We hope this review will provide a versatile guide for tool engineering and applications for recording neurochemical release.
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Affiliation(s)
- Nikki Tjahjono
- Biomedical Engineering Graduate Group, University of California, Davis, Davis, CA, 95616, USA
| | - Yihan Jin
- Neuroscience Graduate Group, University of California, Davis, Davis, CA, 95618, USA
| | - Alice Hsu
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Michael Roukes
- Department of Physics, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Lin Tian
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Davis, CA, 95616, USA.
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8
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Wagdi A, Malan D, Sathyanarayanan U, Beauchamp JS, Vogt M, Zipf D, Beiert T, Mansuroglu B, Dusend V, Meininghaus M, Schneider L, Kalthof B, Wiegert JS, König GM, Kostenis E, Patejdl R, Sasse P, Bruegmann T. Selective optogenetic control of G q signaling using human Neuropsin. Nat Commun 2022; 13:1765. [PMID: 35365606 PMCID: PMC8975936 DOI: 10.1038/s41467-022-29265-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 03/03/2022] [Indexed: 01/07/2023] Open
Abstract
Gq proteins are universally important for signal transduction in mammalian cells. The underlying kinetics and transformation from extracellular stimuli into intracellular signaling, however could not be investigated in detail so far. Here we present the human Neuropsin (hOPN5) for specific and repetitive manipulation of Gq signaling in vitro and in vivo with high spatio-temporal resolution. Properties and G protein specificity of hOPN5 are characterized by UV light induced IP3 generation, Ca2+ transients and inhibition of GIRK channel activity in HEK cells. In adult hearts from a transgenic animal model, light increases the spontaneous beating rate. In addition, we demonstrate light induced contractions in the small intestine, which are not detectable after pharmacological Gq protein block. All-optical high-throughput screening for TRPC6 inhibitors is more specific and sensitive than conventional pharmacological screening. Thus, we demonstrate specific Gq signaling of hOPN5 and unveil its potential for optogenetic applications.
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Affiliation(s)
- Ahmed Wagdi
- grid.411984.10000 0001 0482 5331Institute for Cardiovascular Physiology, University Medical Center Göttingen, Göttingen, Germany ,grid.452396.f0000 0004 5937 5237German Center for Cardiovascular Research (DZHK), Partner site Göttingen, Göttingen, Germany ,grid.7450.60000 0001 2364 4210Present Address: Department of Cardiology and Pulmonology, University Medical Center Göttingen, Georg August University of Göttingen, Göttingen, Germany
| | - Daniela Malan
- grid.10388.320000 0001 2240 3300Institute of Physiology I, Medical Faculty, University of Bonn, Bonn, Germany
| | - Udhayabhaskar Sathyanarayanan
- grid.411984.10000 0001 0482 5331Institute for Cardiovascular Physiology, University Medical Center Göttingen, Göttingen, Germany
| | - Janosch S. Beauchamp
- grid.411984.10000 0001 0482 5331Institute for Cardiovascular Physiology, University Medical Center Göttingen, Göttingen, Germany
| | - Markus Vogt
- grid.411984.10000 0001 0482 5331Institute for Cardiovascular Physiology, University Medical Center Göttingen, Göttingen, Germany
| | - David Zipf
- grid.411984.10000 0001 0482 5331Institute for Cardiovascular Physiology, University Medical Center Göttingen, Göttingen, Germany
| | - Thomas Beiert
- grid.15090.3d0000 0000 8786 803XDepartment of Internal Medicine II, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Berivan Mansuroglu
- grid.10388.320000 0001 2240 3300Institute of Physiology I, Medical Faculty, University of Bonn, Bonn, Germany ,grid.10388.320000 0001 2240 3300Research Training Group 1873, University of Bonn, Bonn, Germany
| | - Vanessa Dusend
- grid.10388.320000 0001 2240 3300Institute of Physiology I, Medical Faculty, University of Bonn, Bonn, Germany ,grid.10388.320000 0001 2240 3300Research Training Group 1873, University of Bonn, Bonn, Germany
| | - Mark Meininghaus
- grid.420044.60000 0004 0374 4101Bayer AG, Research & Development, Pharmaceuticals, 42096 Wuppertal, Germany
| | - Linn Schneider
- grid.420044.60000 0004 0374 4101Bayer AG, Research & Development, Pharmaceuticals, 42096 Wuppertal, Germany
| | - Bernd Kalthof
- grid.420044.60000 0004 0374 4101Bayer AG, Research & Development, Pharmaceuticals, 42096 Wuppertal, Germany
| | - J. Simon Wiegert
- grid.13648.380000 0001 2180 3484Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Gabriele M. König
- grid.10388.320000 0001 2240 3300Molecular, Cellular and Pharmacobiology Section, Institute of Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Evi Kostenis
- grid.10388.320000 0001 2240 3300Molecular, Cellular and Pharmacobiology Section, Institute of Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Robert Patejdl
- grid.413108.f0000 0000 9737 0454Oscar-Langendorff Institute of Physiology, Rostock University Medical Center, Rostock, Germany
| | - Philipp Sasse
- grid.10388.320000 0001 2240 3300Institute of Physiology I, Medical Faculty, University of Bonn, Bonn, Germany
| | - Tobias Bruegmann
- grid.411984.10000 0001 0482 5331Institute for Cardiovascular Physiology, University Medical Center Göttingen, Göttingen, Germany ,grid.452396.f0000 0004 5937 5237German Center for Cardiovascular Research (DZHK), Partner site Göttingen, Göttingen, Germany ,grid.10388.320000 0001 2240 3300Institute of Physiology I, Medical Faculty, University of Bonn, Bonn, Germany ,grid.10388.320000 0001 2240 3300Research Training Group 1873, University of Bonn, Bonn, Germany ,grid.7450.60000 0001 2364 4210Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC), University of Göttingen, Göttingen, Germany
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9
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Kokh DB, Wade RC. G Protein-Coupled Receptor-Ligand Dissociation Rates and Mechanisms from τRAMD Simulations. J Chem Theory Comput 2021; 17:6610-6623. [PMID: 34495672 DOI: 10.1021/acs.jctc.1c00641] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
There is a growing appreciation of the importance of drug-target binding kinetics for lead optimization. For G protein-coupled receptors (GPCRs), which mediate signaling over a wide range of time scales, the drug dissociation rate is often a better predictor of in vivo efficacy than binding affinity, although it is more challenging to compute. Here, we assess the ability of the τ-Random Acceleration Molecular Dynamics (τRAMD) approach to reproduce relative residence times and reveal dissociation mechanisms and the effects of allosteric modulation for two important membrane-embedded drug targets: the β2-adrenergic receptor and the muscarinic acetylcholine receptor M2. The dissociation mechanisms observed in the relatively short RAMD simulations (in which molecular dynamics (MD) simulations are performed using an additional force with an adaptively assigned random orientation applied to the ligand) are in general agreement with much more computationally intensive conventional MD and metadynamics simulations. Remarkably, although decreasing the magnitude of the random force generally reduces the number of egress routes observed, the ranking of ligands by dissociation rate is hardly affected and agrees well with experiment. The simulations also reproduce changes in residence time due to allosteric modulation and reveal associated changes in ligand dissociation pathways.
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Affiliation(s)
- Daria B Kokh
- Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
| | - Rebecca C Wade
- Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany.,Center for Molecular Biology (ZMBH), DKFZ-ZMBH Alliance, Heidelberg University, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany.,Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Im Neuenheimer Feld 205, 69120 Heidelberg, Germany
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10
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Ozenil M, Aronow J, Millard M, Langer T, Wadsak W, Hacker M, Pichler V. Update on PET Tracer Development for Muscarinic Acetylcholine Receptors. Pharmaceuticals (Basel) 2021; 14:530. [PMID: 34199622 PMCID: PMC8229778 DOI: 10.3390/ph14060530] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 05/29/2021] [Accepted: 05/31/2021] [Indexed: 02/07/2023] Open
Abstract
The muscarinic cholinergic system regulates peripheral and central nervous system functions, and, thus, their potential as a therapeutic target for several neurodegenerative diseases is undoubted. A clinically applicable positron emission tomography (PET) tracer would facilitate the monitoring of disease progression, elucidate the role of muscarinic acetylcholine receptors (mAChR) in disease development and would aid to clarify the diverse natural functions of mAChR regulation throughout the nervous system, which still are largely unresolved. Still, no mAChR PET tracer has yet found broad clinical application, which demands mAChR tracers with improved imaging properties. This paper reviews strategies of mAChR PET tracer design and summarizes the binding properties and preclinical evaluation of recent mAChR tracer candidates. Furthermore, this work identifies the current major challenges in mAChR PET tracer development and provides a perspective on future developments in this area of research.
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Affiliation(s)
- Marius Ozenil
- Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, 1090 Wien, Austria; (M.O.); (J.A.); (W.W.); (M.H.)
| | - Jonas Aronow
- Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, 1090 Wien, Austria; (M.O.); (J.A.); (W.W.); (M.H.)
| | - Marlon Millard
- Department of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Vienna, 1090 Wien, Austria; (M.M.); (T.L.)
| | - Thierry Langer
- Department of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Vienna, 1090 Wien, Austria; (M.M.); (T.L.)
| | - Wolfgang Wadsak
- Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, 1090 Wien, Austria; (M.O.); (J.A.); (W.W.); (M.H.)
| | - Marcus Hacker
- Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, 1090 Wien, Austria; (M.O.); (J.A.); (W.W.); (M.H.)
| | - Verena Pichler
- Department of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Vienna, 1090 Wien, Austria; (M.M.); (T.L.)
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11
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Elugoke SE, Adekunle AS, Fayemi OE, Mamba BB, Nkambule TT, Sherif EM, Ebenso EE. Progress in electrochemical detection of neurotransmitters using carbon nanotubes/nanocomposite based materials: A chronological review. NANO SELECT 2020. [DOI: 10.1002/nano.202000082] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Saheed E. Elugoke
- Material Science Innovation and Modelling (MaSIM) Research Focus Area Faculty of Natural and Agricultural Sciences North‐West University (Mafikeng Campus) Mmabatho South Africa
- Department of Chemistry School of Physical and Chemical Sciences Faculty of Natural and Agricultural Sciences North‐West University (Mafikeng Campus) Mmabatho South Africa
| | - Abolanle S. Adekunle
- Material Science Innovation and Modelling (MaSIM) Research Focus Area Faculty of Natural and Agricultural Sciences North‐West University (Mafikeng Campus) Mmabatho South Africa
- Department of Chemistry School of Physical and Chemical Sciences Faculty of Natural and Agricultural Sciences North‐West University (Mafikeng Campus) Mmabatho South Africa
- Department of Chemistry Obafemi Awolowo University PMB Ile‐Ife Nigeria
| | - Omolola E. Fayemi
- Material Science Innovation and Modelling (MaSIM) Research Focus Area Faculty of Natural and Agricultural Sciences North‐West University (Mafikeng Campus) Mmabatho South Africa
- Department of Chemistry School of Physical and Chemical Sciences Faculty of Natural and Agricultural Sciences North‐West University (Mafikeng Campus) Mmabatho South Africa
| | - Bhekie B. Mamba
- Nanotechnology and Water Sustainability Research Unit College of Science Engineering and Technology University of South Africa Johannesburg South Africa
| | - Thabo T.I. Nkambule
- Nanotechnology and Water Sustainability Research Unit College of Science Engineering and Technology University of South Africa Johannesburg South Africa
| | - El‐Sayed M. Sherif
- Center of Excellence for Research in Engineering Materials (CEREM) King Saud University Al‐Riyadh Saudi Arabia
- Electrochemistry and Corrosion Laboratory Department of Physical Chemistry National Research Centre Dokki Cairo Egypt
| | - Eno E. Ebenso
- Material Science Innovation and Modelling (MaSIM) Research Focus Area Faculty of Natural and Agricultural Sciences North‐West University (Mafikeng Campus) Mmabatho South Africa
- Department of Chemistry School of Physical and Chemical Sciences Faculty of Natural and Agricultural Sciences North‐West University (Mafikeng Campus) Mmabatho South Africa
- Nanotechnology and Water Sustainability Research Unit College of Science Engineering and Technology University of South Africa Johannesburg South Africa
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12
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Scida K, Plaxco KW, Jamieson BG. High frequency, real-time neurochemical and neuropharmacological measurements in situ in the living body. Transl Res 2019; 213:50-66. [PMID: 31361988 DOI: 10.1016/j.trsl.2019.07.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 05/20/2019] [Accepted: 07/11/2019] [Indexed: 12/18/2022]
Abstract
The beautiful and complex brain machinery is perfectly synchronized, and our bodies have evolved to protect it against a myriad of potential threats. Shielded physically by the skull and chemically by the blood brain barrier, the brain processes internal and external information so that we can efficiently relate to the world that surrounds us while simultaneously and unconsciously controlling our vital functions. When coupled with the brittle nature of its internal chemical and electric signals, the brain's "armor" render accessing it a challenging and delicate endeavor that has historically limited our understanding of its structural and neurochemical intricacies. In this review, we briefly summarize the advancements made over the past 10 years to decode the brain's neurochemistry and neuropharmacology in situ, at the site of interest in the brain, with special focus on what we consider game-changing emerging technologies (eg, genetically encoded indicators and electrochemical aptamer-based sensors) and the challenges these must overcome before chronic, in situ chemosensing measurements become routine.
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Affiliation(s)
- Karen Scida
- Diagnostic Biochips, Inc., Glen Burnie, Maryland
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California
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13
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Advances in Engineering and Application of Optogenetic Indicators for Neuroscience. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9030562] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Our ability to investigate the brain is limited by available technologies that can record biological processes in vivo with suitable spatiotemporal resolution. Advances in optogenetics now enable optical recording and perturbation of central physiological processes within the intact brains of model organisms. By monitoring key signaling molecules noninvasively, we can better appreciate how information is processed and integrated within intact circuits. In this review, we describe recent efforts engineering genetically-encoded fluorescence indicators to monitor neuronal activity. We summarize recent advances of sensors for calcium, potassium, voltage, and select neurotransmitters, focusing on their molecular design, properties, and current limitations. We also highlight impressive applications of these sensors in neuroscience research. We adopt the view that advances in sensor engineering will yield enduring insights on systems neuroscience. Neuroscientists are eager to adopt suitable tools for imaging neural activity in vivo, making this a golden age for engineering optogenetic indicators.
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14
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Sleno R, Hébert TE. Shaky ground - The nature of metastable GPCR signalling complexes. Neuropharmacology 2019; 152:4-14. [PMID: 30659839 DOI: 10.1016/j.neuropharm.2019.01.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 12/20/2018] [Accepted: 01/16/2019] [Indexed: 01/19/2023]
Abstract
How G protein-coupled receptors (GPCR) interact with one another remains an area of active investigation. Obligate dimers of class C GPCRs such as metabotropic GABA and glutamate receptors are well accepted, although whether this is a general feature of other GPCRs is still strongly debated. In this review, we focus on the idea that GPCR dimers and oligomers are better imagined as parts of larger metastable signalling complexes. We discuss the nature of functional oligomeric entities, their stabilities and kinetic features and how structural and functional asymmetries of such metastable entities might have implications for drug discovery. This article is part of the Special Issue entitled 'Receptor heteromers and their allosteric receptor-receptor interactions'.
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Affiliation(s)
- Rory Sleno
- Marketed Pharmaceuticals and Medical Devices Bureau, Marketed Health Products Directorate, Health Products and Food Branch, Health Canada, Canada
| | - Terence E Hébert
- Department of Pharmacology and Therapeutics, McGill University, Canada.
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15
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Mechanisms of signalling and biased agonism in G protein-coupled receptors. Nat Rev Mol Cell Biol 2018; 19:638-653. [DOI: 10.1038/s41580-018-0049-3] [Citation(s) in RCA: 323] [Impact Index Per Article: 53.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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16
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Picard LP, Schönegge AM, Lohse MJ, Bouvier M. Bioluminescence resonance energy transfer-based biosensors allow monitoring of ligand- and transducer-mediated GPCR conformational changes. Commun Biol 2018; 1:106. [PMID: 30271986 PMCID: PMC6123734 DOI: 10.1038/s42003-018-0101-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 06/20/2018] [Indexed: 12/16/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are seven-transmembrane proteins that mediate a variety of cellular response which make them a target of choice for drug development in many indications. It is now well established that GPCRs can adopt several distinct conformations that can be differentially stabilized by various ligands resulting in different biological outcomes, a concept known as functional selectivity. However, due to the highly hydrophobic nature of GPCRs, tools to monitor these conformational ensembles are limited and addressing their conformation dynamics remains a challenge with current structural biology approaches. Here we describe new bioluminescent resonance energy transfer-based biosensors that can probe the conformational rearrangement promoted by ligands with different signaling efficacies as well as the impact of transducers such as G proteins and β-arrestin on these conformational transitions. The design of such sensors for other receptors should be useful to further explore the structural determinants of GPCR functional selectivity.
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Affiliation(s)
- Louis-Philippe Picard
- Department of Biochemistry and Molecular Medicine, Institute for Research in Immunology and Cancer, Université de Montreal, Montreal, QC, H3C 3J7, Canada
| | - Anne Marie Schönegge
- Department of Biochemistry and Molecular Medicine, Institute for Research in Immunology and Cancer, Université de Montreal, Montreal, QC, H3C 3J7, Canada
- Institute of Pharmacology and Toxicology, 97078, Würzburg, Germany
| | - Martin J Lohse
- Institute of Pharmacology and Toxicology, 97078, Würzburg, Germany
- Max Delbrück Center for Molecular Medicine, 13125, Berlin, Germany
| | - Michel Bouvier
- Department of Biochemistry and Molecular Medicine, Institute for Research in Immunology and Cancer, Université de Montreal, Montreal, QC, H3C 3J7, Canada.
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17
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Tewson P, Martinka S, Shaner N, Berlot C, Quinn AM, Hughes T. Assay for Detecting Gαi-Mediated Decreases in cAMP in Living Cells. SLAS DISCOVERY 2018; 23:898-906. [PMID: 29991302 DOI: 10.1177/2472555218786238] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Cell-based assays to detect Gαi signaling are often indirect, frequently involve complex pharmacological interventions, and are usually blind to the kinetics of the signaling. Our goal was to develop a simple, direct measure of Gαi signaling in living cells. We previously reported our fluorescent cADDis assay and showed that it reliably detects Gαs-mediated increases in cAMP levels. Agonists that stimulate a Gs-coupled receptor produce changes in the intensity of bright green or red fluorescent protein sensors that can be followed over time using automated fluorescence plate readers or fluorescence imaging systems. Since the cADDis sensors can monitor Gαs-mediated increases in adenylyl cyclase activity, in theory they should also be capable of detecting Gαi-mediated decreases. Here we apply our green fluorescent cADDis sensor to the detection of Gαi-mediated inhibition of adenylyl cyclase activity. We validated and optimized the assay in living HEK 293T cells using several known Gαi-coupled receptors and agonists, and we report robust Z' statistics and consistent EC50 responses.
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Affiliation(s)
| | | | - Nathan Shaner
- 2 Department of Photobiology and Bioimaging, The Scintillon Institute, San Diego, CA, USA
| | | | | | - Thomas Hughes
- 1 Montana Molecular, Bozeman, MT, USA.,3 Department of Cell Biology and Neuroscience, Montana State University, Bozeman, MT, USA
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18
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Gorzkiewicz A, Szemraj J. Brain endocannabinoid signaling exhibits remarkable complexity. Brain Res Bull 2018; 142:33-46. [PMID: 29953913 DOI: 10.1016/j.brainresbull.2018.06.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 06/06/2018] [Accepted: 06/21/2018] [Indexed: 01/04/2023]
Abstract
The endocannabinoid (eCB) signaling system is one of the most extensive of the mammalian brain. Despite the involvement of only few specific ligands and receptors, the system encompasses a vast diversity of triggered mechanisms and driven effects. It mediates a wide range of phenomena, including the regulation of transmitter release, neural excitability, synaptic plasticity, impulse spread, long-term neuronal potentiation, neurogenesis, cell death, lineage segregation, cell migration, inflammation, oxidative stress, nociception and the sleep cycle. It is also known to be involved in the processes of learning and memory formation. This extensive scope of action is attained by combining numerous variables. In a properly functioning brain, the correlations of these variables are kept in a strictly controlled balance; however, this balance is disrupted in many pathological conditions. However, while this balance is known to be disrupted by drugs in the case of addicts, the stimuli and mechanisms influencing the neurodegenerating brain remain elusive. This review examines the multiple factors and phenomena affecting the eCB signaling system in the brain. It evaluates techniques of controlling the eCB system to identify the obstacles in their applications and highlights the crucial interdependent variables that may influence biomedical research outcomes.
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Affiliation(s)
- Anna Gorzkiewicz
- Medical University of Lodz, ul.Mazowiecka 6/8, 92-215, Lodz, Poland.
| | - Janusz Szemraj
- Medical University of Lodz, ul.Mazowiecka 6/8, 92-215, Lodz, Poland
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19
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Wang H, Jing M, Li Y. Lighting up the brain: genetically encoded fluorescent sensors for imaging neurotransmitters and neuromodulators. Curr Opin Neurobiol 2018; 50:171-178. [PMID: 29627516 PMCID: PMC5984720 DOI: 10.1016/j.conb.2018.03.010] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 03/19/2018] [Accepted: 03/21/2018] [Indexed: 02/07/2023]
Abstract
Measuring the precise dynamics of specific neurotransmitters and neuromodulators in the brain is essential for understanding how information is transmitted and processed. Thanks to the development and optimization of various genetically encoded sensors, we are approaching the stage in which a few key neurotransmitters/neuromodulators can be imaged with high cell specificity and good signal-to-noise ratio. Here, we summarize recent progress regarding these sensors, focusing on their design principles, properties, potential applications, and current limitations. We also highlight the G protein-coupled receptor (GPCR) scaffold as a promising platform that may enable the scalable development of the next generation of sensors, enabling the rapid, sensitive, and specific detection of a large repertoire of neurotransmitters/neuromodulators in vivo at cellular or even subcellular resolution.
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Affiliation(s)
- Huan Wang
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China; PKU-IDG/McGovern Institute for Brain Research, Beijing 100871, China
| | - Miao Jing
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China; PKU-IDG/McGovern Institute for Brain Research, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Beijing 100871, China
| | - Yulong Li
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China; PKU-IDG/McGovern Institute for Brain Research, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Beijing 100871, China.
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20
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Liu Y, Zeng H, Pediani JD, Ward RJ, Chen LY, Wu N, Ma L, Tang M, Yang Y, An S, Guo XX, Hao Q, Xu TR. Visualization of the activation of the histamine H3 receptor (H3R) using novel fluorescence resonance energy transfer biosensors and their potential application to the study of H3R pharmacology. FEBS J 2018; 285:2319-2336. [PMID: 29701013 DOI: 10.1111/febs.14484] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 03/24/2018] [Accepted: 04/20/2018] [Indexed: 12/14/2022]
Abstract
Activation of the histamine-3 receptor (H3R) is involved in memory processes and cognitive action, while blocking H3R activation can slow the progression of neurological disorders, such as Alzheimer's disease, schizophrenia and narcolepsy. To date, however, no direct way to examine the activation of H3R has been utilized. Here, we describe a novel biosensor that can visualize the activation of H3R through an intramolecular fluorescence resonance energy transfer (FRET) signal. To achieve this, we constructed an intramolecular H3R FRET sensor with cyan fluorescent protein (CFP) attached at the C terminus and yellow fluorescent protein (YFP) inserted into the third intracellular loop. The sensor was found to internalize normally on agonist treatment. We measured FRET signals between the donor CFP and the acceptor YFP in living cells in real time, the results of which indicated that H3R agonist treatment (imetit or histamine) increases the FRET signal in a time- and concentration-dependent manner with Kon and Koff values consistent with published data and which maybe correlated with decreasing cAMP levels and the promotion of ERK1/2 phosphorylation. The FRET signal was inhibited by H3R antagonists, and the introduction of mutations at F419A, F423A, L426A and L427A, once again, the promotion of ERK1/2 phosphorylation, was diminished. Thus, we have built a H3R biosensor which can visualize the activation of receptor through real-time structure changes and which can obtain pharmacological kinetic data at the same time. The FRET signals may allow the sensor to become a useful tool for screening compounds and optimizing useful ligands.
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Affiliation(s)
- Ying Liu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, China
| | - Hong Zeng
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, China
| | - John D Pediani
- Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, UK
| | - Richard J Ward
- Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, UK
| | - Lu-Yao Chen
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, China
| | - Nan Wu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, China
| | - Li Ma
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, China
| | - Mei Tang
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, China
| | - Yang Yang
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, China
| | - Su An
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, China
| | - Xiao-Xi Guo
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, China
| | - Qian Hao
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, China
| | - Tian-Rui Xu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, China
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21
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Wang A, Feng J, Li Y, Zou P. Beyond Fluorescent Proteins: Hybrid and Bioluminescent Indicators for Imaging Neural Activities. ACS Chem Neurosci 2018; 9:639-650. [PMID: 29482322 DOI: 10.1021/acschemneuro.7b00455] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Optical biosensors have been invaluable tools in neuroscience research, as they provide the ability to directly visualize neural activity in real time, with high specificity, and with exceptional spatial and temporal resolution. Notably, a majority of these sensors are based on fluorescent protein scaffolds, which offer the ability to target specific cell types or even subcellular compartments. However, fluorescent proteins are intrinsically bulky tags, often insensitive to the environment, and always require excitation light illumination. To address these limitations, there has been a proliferation of alternative sensor scaffolds developed in recent years, including hybrid sensors that combine the advantages of synthetic fluorophores and genetically encoded protein tags, as well as bioluminescent probes. While still in their early stage of development as compared with fluorescent protein-based sensors, these novel probes have offered complementary solutions to interrogate various aspects of neuronal communication, including transmitter release, changes in membrane potential, and the production of second messengers. In this Review, we discuss these important new developments with a particular focus on design strategies.
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Affiliation(s)
- Anqi Wang
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Jiesi Feng
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Yulong Li
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Peng Zou
- College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
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22
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Sleno R, Hébert TE. The Dynamics of GPCR Oligomerization and Their Functional Consequences. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2018; 338:141-171. [PMID: 29699691 DOI: 10.1016/bs.ircmb.2018.02.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The functional importance of G protein-coupled receptor (GPCR) oligomerization remains controversial. Although obligate dimers of class C GPCRs are well accepted, the generalizability of this phenomenon is still strongly debated with respect to other classes of GPCRs. In this review, we focus on understanding the organization and dynamics between receptor equivalents and their signaling partners in oligomeric receptor complexes, with a view toward integrating disparate viewpoints into a unified understanding. We discuss the nature of functional oligomeric entities, and how asymmetries in receptor structure and function created by oligomers might have implications for receptor function as allosteric machines and for future drug discovery.
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23
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Liu Y, Chen LY, Zeng H, Ward R, Wu N, Ma L, Mu X, Li QL, Yang Y, An S, Guo XX, Hao Q, Xu TR. Assessing the real-time activation of the cannabinoid CB1 receptor and the associated structural changes using a FRET biosensor. Int J Biochem Cell Biol 2018; 99:114-124. [PMID: 29626639 DOI: 10.1016/j.biocel.2018.04.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 03/25/2018] [Accepted: 04/04/2018] [Indexed: 11/18/2022]
Abstract
The cannabinoid receptor 1 (CB1) is mainly expressed in the nervous system and regulates learning, memory processes, pain and energy metabolism. However, there is no way to directly measure its activation. In this study, we constructed a CB1 intramolecular fluorescence resonance energy transfer (FRET) sensor, which could measure CB1 activation by monitoring structural changes between the third intracellular loop and the C-terminal tail. CB1 agonists induced a time- and concentration-dependent increase in the FRET signal, corresponding to a reduction in the distance between the third intracellular loop and the C-terminal tail. This, in turn, mobilized intracellular Ca2+, inhibited cAMP accumulation, and increased phosphorylation of the ERK1/2 MAP kinases. The activation kinetics detected using this method were consistent with those from previous reports. Moreover, the increased FRET signal was markedly inhibited by the CB1 antagonist rimonabant, which also reduced phosphorylation of the ERK1/2 MAP kinases. We mutated a single cysteine residue in the sensor (at position 257 or 264) to alanine. Both mutation reduced the agonist-induced increase in FRET signal and structural changes in the CB1 receptor, which attenuated phosphorylation of the ERK1/2 MAP kinases. In summary, our sensor directly assesses the kinetics of CB1 activation in real-time and can be used to monitor CB1 structure and function.
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Affiliation(s)
- Ying Liu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Lu-Yao Chen
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Hong Zeng
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Richard Ward
- Center for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Nan Wu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Li Ma
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Xi Mu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Qiu-Lan Li
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Yang Yang
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Su An
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Xiao-Xi Guo
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Qian Hao
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Tian-Rui Xu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China.
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24
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Kauk M, Hoffmann C. Intramolecular and Intermolecular FRET Sensors for GPCRs - Monitoring Conformational Changes and Beyond. Trends Pharmacol Sci 2017; 39:123-135. [PMID: 29180026 DOI: 10.1016/j.tips.2017.10.011] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 10/27/2017] [Accepted: 10/31/2017] [Indexed: 11/18/2022]
Abstract
Within the past decade, a large increase in structural knowledge from crystallographic studies has significantly fostered our understanding of the structural biology of G protein-coupled receptors (GPCRs). However, information on dynamic events upon receptor activation or deactivation is not yet readily accessed by these structural approaches. GPCR-based fluorescence resonance energy transfer or bioluminescence resonance energy transfer sensors or sensors for interacting proteins (e.g., G proteins or arrestins) can in part cover this gap. The principal design of such sensors was reported 15 years ago. Since then, sensors for almost 20 different GPCRs have been designed. If used with necessary controls and cautious interpretation, such sensors can contribute significantly to our understanding of the basic mechanisms of GPCR function and beyond. In this review, we will discuss the recent developments in this area of GPCR dynamics.
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Affiliation(s)
- Michael Kauk
- Department of Pharmacology and Toxicology, University of Würzburg, Versbacher Straße 9, 97078 Würzburg, Germany
| | - Carsten Hoffmann
- Department of Pharmacology and Toxicology, University of Würzburg, Versbacher Straße 9, 97078 Würzburg, Germany; Institut für Molekulare Zellbiologie, CMB - Center for Molecular Biomedicine, Universitätsklinikum Jena, Friedrich-Schiller-Universität Jena, Hans-Knöll Straße 2, D-07745 Jena, Germany.
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25
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Bock A, Schrage R, Mohr K. Allosteric modulators targeting CNS muscarinic receptors. Neuropharmacology 2017; 136:427-437. [PMID: 28935216 DOI: 10.1016/j.neuropharm.2017.09.024] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 09/13/2017] [Accepted: 09/15/2017] [Indexed: 12/21/2022]
Abstract
Muscarinic acetylcholine receptors are G protein-coupled receptors (GPCRs) which are broadly expressed in the central nervous system (CNS) and other tissues in the periphery. They emerge as important drug targets for a number of diseases including Alzheimer's disease, Parkinson's disease, and schizophrenia. Muscarinic receptors are divided into five subtypes (M1-M5) of which M1-M4 have been crystalized. All subtypes possess at least one allosteric binding site which is located in the extracellular region of the receptor on top of the ACh (i.e. orthosteric) binding site. The former can be specifically targeted by chemical compounds (mostly small molecules) and binding of such allosteric modulators affects the affinity and/or efficacy of orthosteric ligands. This allows highly specific modulation of GPCR function and, from a drug discovery point of view, may be advantageous in terms of subtype selectivity and biased signaling. There is a plethora of allosteric modulators for all five muscarinic receptor subtypes. This review presents the basic principles of allosteric modulation of GPCRs on both the molecular and structural level focusing on allosteric modulators of the muscarinic receptor family. Further we discuss dualsteric (i.e. bitopic orthosteric/allosteric) ligands emphasizing their potential in modulating muscarinic receptor dynamics and signaling. The common mechanisms of muscarinic receptor allosteric modulation have been proven to be generalizable and are at play at many, if not all GPCRs. Given this paradigmatic role of muscarinic receptors we suggest that also new developments in muscarinic allosteric modulation may also be extended to other members of the GPCR superfamily. This article is part of the Special Issue entitled 'Neuropharmacology on Muscarinic Receptors'.
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Affiliation(s)
- Andreas Bock
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany; Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Strasse 9, 97078 Würzburg, Germany.
| | - Ramona Schrage
- Pharmacology and Toxicology Section, Institute of Pharmacy, University of Bonn, Gerhard-Domagk-Strasse 3, 53121 Bonn, Germany
| | - Klaus Mohr
- Pharmacology and Toxicology Section, Institute of Pharmacy, University of Bonn, Gerhard-Domagk-Strasse 3, 53121 Bonn, Germany
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26
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Bidirectional allosteric interactions between cannabinoid receptor 1 (CB 1) and dopamine receptor 2 long (D 2L) heterotetramers. Eur J Pharmacol 2017; 813:66-83. [PMID: 28734930 DOI: 10.1016/j.ejphar.2017.07.034] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 07/18/2017] [Accepted: 07/18/2017] [Indexed: 01/22/2023]
Abstract
Type 1 cannabinoid (CB1) and dopamine 2 long form (D2L) receptors can physically interact to form heteromers that display unique pharmacology in vitro compared to homomeric complexes. Co-expression of CB1 and D2L and co-application of CB1 and D2 agonists increases cAMP levels while administration of either agonist alone decreases cAMP levels. To understand the observed co-agonist response, our first goal of the current study was to define the stoichiometry of CB1/D2L/Gα protein complexes. Using bioluminescence resonance energy transfer 2 (BRET2), we confirmed that, CB1 homodimers, D2L homodimers, and CB1/D2L heteromers are formed. By using sequential resonance energy transfer 2 (SRET2) combined with bimolecular fluorescence complementation (BiFC), we were able to demonstrate that CB1/D2L form heterotetramers consisting of CB1 and D2L homodimers. We demonstrated that CB1/D2L heterotetramers are coupled to at least two Gα proteins. The second aim of the study was to investigate allosteric effects of a D2L agonist (quinpirole) on CB1 receptor function and to investigate the effects of a CB1 agonist [arachidonyl-2-chloroethylamide (ACEA)] on D2L receptor function within CB1/D2L heterotetramers. Treating cells co-expressing CB1 and D2L with both ACEA and quinpirole switched CB1 and D2L receptor coupling and signaling from Gαi to Gαs proteins, enhanced β-arrestin1 recruitment and receptor co-internalization. The concept of bidirectional allosteric interaction within CB1/D2 heterotetramers has important implications for understanding the activity of receptor complexes in native tissues and under pathological conditions.
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Sleno R, Devost D, Pétrin D, Zhang A, Bourque K, Shinjo Y, Aoki J, Inoue A, Hébert TE. Conformational biosensors reveal allosteric interactions between heterodimeric AT1 angiotensin and prostaglandin F2α receptors. J Biol Chem 2017; 292:12139-12152. [PMID: 28584054 DOI: 10.1074/jbc.m117.793877] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 05/31/2017] [Indexed: 11/06/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are conformationally dynamic proteins transmitting ligand-encoded signals in multiple ways. This transmission is highly complex and achieved through induction of distinct GPCR conformations, which preferentially drive specific receptor-mediated signaling events. This conformational capacity can be further enlarged via allosteric effects between dimers, warranting further study of these effects. Using GPCR conformation-sensitive biosensors, we investigated allosterically induced conformational changes in the recently reported F prostanoid (FP)/angiotensin II type 1 receptor (AT1R) heterodimer. Ligand occupancy of the AT1R induced distinct conformational changes in FP compared with those driven by PGF2α in bioluminescence resonance energy transfer (BRET)-based FP biosensors engineered with Renilla luciferase (RLuc) as an energy donor in the C-tail and fluorescein arsenical hairpin binder (FlAsH)-labeled acceptors at different positions in the intracellular loops. We also found that this allosteric communication is mediated through Gαq and may also involve proximal (phospholipase C) but not distal (protein kinase C) signaling partners. Interestingly, β-arrestin-biased AT1R agonists could also transmit a Gαq-dependent signal to FP without activation of downstream Gαq signaling. This transmission of information was specific to the AT1R/FP complex, as activation of Gαq by the oxytocin receptor did not recapitulate the same phenomenon. Finally, information flow was asymmetric in the sense that FP activation had negligible effects on AT1R-based conformational biosensors. The identification of partner-induced GPCR conformations may help identify novel allosteric effects when investigating multiprotein receptor signaling complexes.
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Affiliation(s)
- Rory Sleno
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec H3G 1Y6, Canada
| | - Dominic Devost
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec H3G 1Y6, Canada
| | - Darlaine Pétrin
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec H3G 1Y6, Canada
| | - Alice Zhang
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec H3G 1Y6, Canada
| | - Kyla Bourque
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec H3G 1Y6, Canada
| | - Yuji Shinjo
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Junken Aoki
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan; Japan Agency for Medical Research and Development, Core Research for Evolutional Science and Technology (AMED-CREST), Chiyoda-ku, Tokyo 100-0004, Japan
| | - Asuka Inoue
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan; Japan Science and Technology Agency (JST), Precursory Research for Embryonic Science and Technology (PRESTO), Kawaguchi, Saitama 332-0012, Japan
| | - Terence E Hébert
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec H3G 1Y6, Canada.
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Methods used to study the oligomeric structure of G-protein-coupled receptors. Biosci Rep 2017; 37:BSR20160547. [PMID: 28062602 PMCID: PMC5398257 DOI: 10.1042/bsr20160547] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 01/05/2017] [Accepted: 01/06/2017] [Indexed: 02/02/2023] Open
Abstract
G-protein-coupled receptors (GPCRs), which constitute the largest family of cell surface receptors, were originally thought to function as monomers, but are now recognized as being able to act in a wide range of oligomeric states and indeed, it is known that the oligomerization state of a GPCR can modulate its pharmacology and function. A number of experimental techniques have been devised to study GPCR oligomerization including those based upon traditional biochemistry such as blue-native PAGE (BN-PAGE), co-immunoprecipitation (Co-IP) and protein-fragment complementation assays (PCAs), those based upon resonance energy transfer, FRET, time-resolved FRET (TR-FRET), FRET spectrometry and bioluminescence resonance energy transfer (BRET). Those based upon microscopy such as FRAP, total internal reflection fluorescence microscopy (TIRFM), spatial intensity distribution analysis (SpIDA) and various single molecule imaging techniques. Finally with the solution of a growing number of crystal structures, X-ray crystallography must be acknowledged as an important source of discovery in this field. A different, but in many ways complementary approach to the use of more traditional experimental techniques, are those involving computational methods that possess obvious merit in the study of the dynamics of oligomer formation and function. Here, we summarize the latest developments that have been made in the methods used to study GPCR oligomerization and give an overview of their application.
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Messerer R, Kauk M, Volpato D, Alonso Canizal MC, Klöckner J, Zabel U, Nuber S, Hoffmann C, Holzgrabe U. FRET Studies of Quinolone-Based Bitopic Ligands and Their Structural Analogues at the Muscarinic M 1 Receptor. ACS Chem Biol 2017; 12:833-843. [PMID: 28117571 DOI: 10.1021/acschembio.6b00828] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Aiming to design partial agonists as well as allosteric modulators for the M1 muscarinic acetylcholine (M1AChR) receptor, two different series of bipharmacophoric ligands and their structural analogues were designed and synthesized. The hybrids were composed of the benzyl quinolone carboxylic acid (BQCA)-derived subtype selective allosteric modulator 3 and the orthosteric building block 4-((4,5-dihydroisoxazol-3-yl)oxy)-N,N-dimethylbut-2-yn-1-amine (base of iperoxo) 1 or the endogenous ligand 2-(dimethylamino)ethyl acetate (base of acetylcholine) 2, respectively. The two pharmacophores were linked via alkylene chains of different lengths (C4, C6, C8, and C10). Furthermore, the corresponding structural analogues of 1 and 2 and of modified BQCA 3 with varying alkyl chain length between C2 and C10 were investigated. Fluorescence resonance energy transfer (FRET) measurements in a living single cell system were investigated in order to understand how these compounds interact with a G protein-coupled receptor (GPCR) on a molecular level and how the single moieties contribute to ligand receptor interaction. The characterization of the modified orthosteric ligands indicated that a linker attached to an orthoster rapidly attenuates the receptor response. Linker length elongation increases the receptor response of bitopic ligands, until reaching a maximum, followed by a gradual decrease. The optimal linker length was found to be six methylene groups at the M1AChR. A new conformational change is described that is not of inverse agonistic origin for long linker bitopic ligands and was further investigated by exceptional fragment-based screening approaches.
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Affiliation(s)
- Regina Messerer
- Department
of Pharmaceutical and Medical Chemistry, Institute of Pharmacy, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Michael Kauk
- Department
of Pharmacology and Toxicology, University of Würzburg, Versbacher
Str. 9, 97078 Würzburg, Germany
- Rudolf
Virchow Center for Experimental Biomedicine, University of Würzburg, Josef Schneider Straße 2, 97080 Würzburg, Germany
| | - Daniela Volpato
- Department
of Pharmaceutical and Medical Chemistry, Institute of Pharmacy, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Maria Consuelo Alonso Canizal
- Department
of Pharmacology and Toxicology, University of Würzburg, Versbacher
Str. 9, 97078 Würzburg, Germany
- Rudolf
Virchow Center for Experimental Biomedicine, University of Würzburg, Josef Schneider Straße 2, 97080 Würzburg, Germany
| | - Jessika Klöckner
- Department
of Pharmaceutical and Medical Chemistry, Institute of Pharmacy, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Ulrike Zabel
- Department
of Pharmacology and Toxicology, University of Würzburg, Versbacher
Str. 9, 97078 Würzburg, Germany
- Rudolf
Virchow Center for Experimental Biomedicine, University of Würzburg, Josef Schneider Straße 2, 97080 Würzburg, Germany
| | - Susanne Nuber
- Department
of Pharmacology and Toxicology, University of Würzburg, Versbacher
Str. 9, 97078 Würzburg, Germany
- Rudolf
Virchow Center for Experimental Biomedicine, University of Würzburg, Josef Schneider Straße 2, 97080 Würzburg, Germany
| | - Carsten Hoffmann
- Department
of Pharmacology and Toxicology, University of Würzburg, Versbacher
Str. 9, 97078 Würzburg, Germany
- Rudolf
Virchow Center for Experimental Biomedicine, University of Würzburg, Josef Schneider Straße 2, 97080 Würzburg, Germany
| | - Ulrike Holzgrabe
- Department
of Pharmaceutical and Medical Chemistry, Institute of Pharmacy, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
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30
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Bagheri F, Piri K, Mohsenifar A, Ghaderi S. FRET-based nanobiosensor for detection of scopolamine in hairy root extraction of Atropa belladonna. Talanta 2017; 164:593-600. [PMID: 28107978 DOI: 10.1016/j.talanta.2016.12.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 12/02/2016] [Accepted: 12/06/2016] [Indexed: 11/16/2022]
Abstract
A simple, sensitive, selective, and rapid optical nanobiosensor based on FRET was designed to detect tropane alkaloids as anti-cholinergic agents in natural and transgenic hairy roots extracts of Atropa belladonna. To achieve that, conjugation of tioglycolyic acid capped cadmium telluride quantum Dots, M2 muscarinic receptor (Cd/Te QDs-M2R) and conjugation of scopolamine-rhodamine123 (Sc-Rho123) were performed. More specifically, proportional amounts of M2 muscarinic receptor and quantum dots (QDs) were conjugated while scopolamine (as a tropane alkaloid) and rhodamine123 were also combined and these moieties functioned as donor and acceptor pairs, respectively. The system response was linear over the range of 0.01-4µmolL-1 of scopolamine hydrochloride concentration with a detection limit of 0.001µmolL-1. The developed nanobiosensor was successfully used for in vitro recognition of scopolamine as an anti-cholinergic agent in the investigated plant extracts. In addition, Agrobacterium rhizogenesis mediated gene transfer technique was employed to generate hairy roots and to enhance the production of tropane alkaloids in the studied medicinal plant.
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Affiliation(s)
- Fereshte Bagheri
- Department of Biotechnology, College of Agriculture, Bu-Ali Sina University, Hamedan, Iran; Research Pharmaceutical Center, School of pharmacy, Kermanshah University of Medical Sciences, Kermanshah, Iran.
| | - Khosro Piri
- Department of Biotechnology, College of Agriculture, Bu-Ali Sina University, Hamedan, Iran.
| | | | - Smaiil Ghaderi
- Department of Chemistry, Bu-Ali Sina University, Hamedan, Iran
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31
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Devost D, Sleno R, Pétrin D, Zhang A, Shinjo Y, Okde R, Aoki J, Inoue A, Hébert TE. Conformational Profiling of the AT1 Angiotensin II Receptor Reflects Biased Agonism, G Protein Coupling, and Cellular Context. J Biol Chem 2017; 292:5443-5456. [PMID: 28213525 DOI: 10.1074/jbc.m116.763854] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 02/03/2017] [Indexed: 12/16/2022] Open
Abstract
Here, we report the design and use of G protein-coupled receptor-based biosensors to monitor ligand-mediated conformational changes in receptors in intact cells. These biosensors use bioluminescence resonance energy transfer with Renilla luciferase (RlucII) as an energy donor, placed at the distal end of the receptor C-tail, and the small fluorescent molecule FlAsH as an energy acceptor, its binding site inserted at different positions throughout the intracellular loops and C-terminal tail of the angiotensin II type I receptor. We verified that the modifications did not compromise receptor localization or function before proceeding further. Our biosensors were able to capture effects of both canonical and biased ligands, even to the extent of discriminating between different biased ligands. Using a combination of G protein inhibitors and HEK 293 cell lines that were CRISPR/Cas9-engineered to delete Gαq, Gα11, Gα12, and Gα13 or β-arrestins, we showed that Gαq and Gα11 are required for functional responses in conformational sensors in ICL3 but not ICL2. Loss of β-arrestin did not alter biased ligand effects on ICL2P2. We also demonstrate that such biosensors are portable between different cell types and yield context-dependent readouts of G protein-coupled receptor conformation. Our study provides mechanistic insights into signaling events that depend on either G proteins or β-arrestin.
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Affiliation(s)
- Dominic Devost
- From the Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec H3G 1Y6, Canada
| | - Rory Sleno
- From the Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec H3G 1Y6, Canada
| | - Darlaine Pétrin
- From the Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec H3G 1Y6, Canada
| | - Alice Zhang
- From the Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec H3G 1Y6, Canada
| | - Yuji Shinjo
- the Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Rakan Okde
- From the Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec H3G 1Y6, Canada
| | - Junken Aoki
- the Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan.,the Japan Agency for Medical Research and Development-Core Research for Evolutional Science and Technology (AMED-CREST), Chiyoda-ku, Tokyo 100-0004, Japan, and
| | - Asuka Inoue
- the Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan.,the Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012, Japan
| | - Terence E Hébert
- From the Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec H3G 1Y6, Canada,
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32
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Bourque K, Pétrin D, Sleno R, Devost D, Zhang A, Hébert TE. Distinct Conformational Dynamics of Three G Protein-Coupled Receptors Measured Using FlAsH-BRET Biosensors. Front Endocrinol (Lausanne) 2017; 8:61. [PMID: 28439254 PMCID: PMC5383666 DOI: 10.3389/fendo.2017.00061] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 03/21/2017] [Indexed: 12/30/2022] Open
Abstract
A number of studies have profiled G protein-coupled receptor (GPCR) conformation using fluorescent biaresenical hairpin binders (FlAsH) as acceptors for BRET or FRET. These conformation-sensitive biosensors allow reporting of movements occurring on the intracellular surface of a receptor to investigate mechanisms of receptor activation and function. Here, we generated eight FlAsH-BRET-based biosensors within the sequence of the β2-adrenergic receptor (β2AR) and compared agonist-induced responses to the angiotensin II receptor type I (AT1R) and the prostaglandin F2α receptor (FP). Although all three receptors had FlAsH-binding sequences engineered into the third intracellular loops and carboxyl-terminal domain, both the magnitude and kinetics of the BRET responses to ligand were receptor-specific. Biosensors in ICL3 of both the AT1R and FP responded robustly when stimulated with their respective full agonists as opposed to the β2AR where responses in the third intracellular loop were weak and transient when engaged by isoproterenol. C-tail sensors responses were more robust in the β2AR and AT1R but not in FP. Even though GPCRs share the heptahelical topology and are expressed in the same cellular background, different receptors have unique conformational fingerprints.
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Affiliation(s)
- Kyla Bourque
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, Canada
| | - Darlaine Pétrin
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, Canada
| | - Rory Sleno
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, Canada
| | - Dominic Devost
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, Canada
| | - Alice Zhang
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, Canada
| | - Terence E. Hébert
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, Canada
- *Correspondence: Terence E. Hébert,
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Baginskas A, Kuras A. Retinal co-mediator acetylcholine evokes muscarinic inhibition of recurrent excitation in frog tectum column. Neurosci Lett 2016; 629:137-142. [PMID: 27394688 DOI: 10.1016/j.neulet.2016.07.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 06/27/2016] [Accepted: 07/06/2016] [Indexed: 12/13/2022]
Abstract
Acetylcholine receptors contribute to the control of neuronal and neuronal network activity from insects to humans. We have investigated the action of acetylcholine receptors in the optic tectum of Rana temporaria (common frog). Our previous studies have demonstrated that acetylcholine activates presynaptic nicotinic receptors, when released into the frog optic tectum as a co-mediator during firing of a single retinal ganglion cell, and causes: a) potentiation of retinotectal synaptic transmission, and b) facilitation of transition of the tectum column to a higher level of activity. In the present study we have shown that endogenous acetylcholine also activates muscarinic receptors, leading to a delayed inhibition of recurrent excitatory synaptic transmission in the tectum column. The delay of muscarinic inhibition was evaluated to be of ∼80ms, with an extent of inhibition of ∼2 times. The inhibition of the recurrent excitation determines transition of the tectum column back to its resting state, giving a functional sense for the inhibition.
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Affiliation(s)
- Armantas Baginskas
- Department of Physics, Mathematics and Biophysics, Medical Academy, Lithuanian University of Health Sciences, Eiveniu 4, Kaunas LT 50161, Lithuania.
| | - Antanas Kuras
- Laboratory of Neurophysiology, Neuroscience Institute, Medical Academy, Lithuanian University of Health Sciences, Eiveniu 4, Kaunas LT 50161, Lithuania
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34
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Stumpf AD, Hoffmann C. Optical probes based on G protein-coupled receptors - added work or added value? Br J Pharmacol 2015; 173:255-66. [PMID: 26562218 DOI: 10.1111/bph.13382] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 09/22/2015] [Accepted: 10/26/2015] [Indexed: 12/22/2022] Open
Abstract
In 2003, the first report was published that presented proof of principle for a novel class of FRET biosensors for use in living cells. This novel sensor class was built on the base of GPCRs, which represent an integral transmembrane receptor family passing the membrane seven times and are thus also called the 7TM receptor family. As an estimated number of 30% of all marketed drugs exert their effects by modulating GPCR function, these initial reports promised the gain of novel insights into receptor function. Such FRET sensors have slowly, but progressively, made their way into the standard toolbox for GPCR research as several groups are now reporting on the generation and use of these sensors. By now, FRET sensors have been reported for 18 different GPCRs, and more are expected to be added. These particular receptor sensors have been used to investigate receptor dynamics in living cells to evaluate ligand binding and ligand efficacy in real time, to study voltage and mechanosensitivity of GPCRs or to study the influence of receptor polymorphisms on receptor function in real-time. In this review we will describe the different design principles of these GPCR-based sensors and will summarize their current biological applications in living cells.
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Affiliation(s)
- A D Stumpf
- Bio-Imaging Center, Rudolf-Virchow-Zentrum für Experimentelle Medizin, University of Würzburg, Würzburg, Germany.,Department of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
| | - C Hoffmann
- Bio-Imaging Center, Rudolf-Virchow-Zentrum für Experimentelle Medizin, University of Würzburg, Würzburg, Germany.,Department of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
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35
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Sleno R, Pétrin D, Devost D, Goupil E, Zhang A, Hébert TE. Designing BRET-based conformational biosensors for G protein-coupled receptors. Methods 2015; 92:11-8. [PMID: 25962643 DOI: 10.1016/j.ymeth.2015.05.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 04/30/2015] [Accepted: 05/02/2015] [Indexed: 12/16/2022] Open
Abstract
Ligand-biased signaling is starting to have significant impact on drug discovery programs in the pharmaceutical industry and has reinvigorated our understanding of pharmacological efficacy. As such, many investigators and screening campaigns are now being directed at a larger section of the signaling responses downstream of an individual G protein-coupled receptor. Many biosensor-based platforms have been developed to capture signaling signatures. Despite our growing ability to use such signaling signatures, we remain hampered by the fact that signaling signatures may be particular to an individual cell type and thus our platforms may not be portable from cell to cell, necessitating further cell-specific biosensor development. Here, we provide a complementary strategy based on capturing receptor-proximal conformational profiles using intra-molecular BRET-based sensors composed of a Renilla luciferase donor engineered into the carboxy-terminus and CCPGCC motifs which bind fluorescent hairpin arsenical dyes engineered into different positions in intracellular loop 3 of FP, the receptor for PGF2α. We discuss the design and optimization of such sensors for orthosteric and allosteric ligands.
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Affiliation(s)
- Rory Sleno
- Department of Pharmacology and Therapeutics, McGill University, Canada
| | - Darlaine Pétrin
- Department of Pharmacology and Therapeutics, McGill University, Canada
| | - Dominic Devost
- Department of Pharmacology and Therapeutics, McGill University, Canada
| | - Eugénie Goupil
- Department of Pharmacology and Therapeutics, McGill University, Canada
| | - Alice Zhang
- Department of Pharmacology and Therapeutics, McGill University, Canada
| | - Terence E Hébert
- Department of Pharmacology and Therapeutics, McGill University, Canada.
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36
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Sridharan R, Zuber J, Connelly SM, Mathew E, Dumont ME. Fluorescent approaches for understanding interactions of ligands with G protein coupled receptors. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1838:15-33. [PMID: 24055822 PMCID: PMC3926105 DOI: 10.1016/j.bbamem.2013.09.005] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 09/03/2013] [Accepted: 09/08/2013] [Indexed: 11/18/2022]
Abstract
G protein coupled receptors are responsible for a wide variety of signaling responses in diverse cell types. Despite major advances in the determination of structures of this class of receptors, the underlying mechanisms by which binding of different types of ligands specifically elicits particular signaling responses remain unclear. The use of fluorescence spectroscopy can provide important information about the process of ligand binding and ligand dependent conformational changes in receptors, especially kinetic aspects of these processes that can be difficult to extract from X-ray structures. We present an overview of the extensive array of fluorescent ligands that have been used in studies of G protein coupled receptors and describe spectroscopic approaches for assaying binding and probing the environment of receptor-bound ligands with particular attention to examples involving yeast pheromone receptors. In addition, we discuss the use of fluorescence spectroscopy for detecting and characterizing conformational changes in receptors induced by the binding of ligands. Such studies have provided strong evidence for diversity of receptor conformations elicited by different ligands, consistent with the idea that GPCRs are not simple on and off switches. This diversity of states constitutes an underlying mechanistic basis for biased agonism, the observation that different stimuli can produce different responses from a single receptor. It is likely that continued technical advances will allow fluorescence spectroscopy to play an important role in continued probing of structural transitions in G protein coupled receptors. This article is part of a Special Issue entitled: Structural and biophysical characterisation of membrane protein-ligand binding.
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Affiliation(s)
- Rajashri Sridharan
- Department of Biochemistry and Biophysics, P.O. Box 712, University of Rochester Medical Center, Rochester, NY 14642
| | - Jeffrey Zuber
- Department of Biochemistry and Biophysics, P.O. Box 712, University of Rochester Medical Center, Rochester, NY 14642
| | - Sara M. Connelly
- Department of Biochemistry and Biophysics, P.O. Box 712, University of Rochester Medical Center, Rochester, NY 14642
| | - Elizabeth Mathew
- Department of Biochemistry and Biophysics, P.O. Box 712, University of Rochester Medical Center, Rochester, NY 14642
| | - Mark E. Dumont
- Department of Biochemistry and Biophysics, P.O. Box 712, University of Rochester Medical Center, Rochester, NY 14642
- Department of Pediatrics, P.O. Box 777, University of Rochester Medical Center, Rochester, NY 14642
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37
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Lohse MJ, Maiellaro I, Calebiro D. Kinetics and mechanism of G protein-coupled receptor activation. Curr Opin Cell Biol 2013; 27:87-93. [PMID: 24530699 DOI: 10.1016/j.ceb.2013.11.009] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 11/24/2013] [Indexed: 10/25/2022]
Abstract
The activation of a G protein-coupled receptor is generally triggered by binding of an agonist to the receptor's binding pocket, or, in the case of rhodopsin, by light-induced changes of the pre-bound retinal. This is followed by a series of a conformational changes towards an active receptor conformation, which is capable of signalling to G proteins and other downstream proteins. In the past few years, a number of new techniques have been employed to analyze the kinetics of this activation process, including X-ray crystallographic three-dimensional structures of receptors in the inactive and the active states, NMR studies of labelled receptors, molecular simulations, and optical analyses with fluorescence resonance energy transfer (FRET). Here we review our current understanding of the activation process of GPCRs as well as open questions in the sequence of events ranging from (sub-)microsecond activation by light or agonist binding to millisecond activation of receptors by soluble ligands and the subsequent generation of an intracellular signal.
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Affiliation(s)
- Martin J Lohse
- Institute of Pharmacology and Toxicology, University of Würzburg, 97078 Würzburg, Germany; Rudolf Virchow Center, DFG-Research Center for Experimental Biomedicine, University of Würzburg, 97078 Würzburg, Germany.
| | - Isabella Maiellaro
- Institute of Pharmacology and Toxicology, University of Würzburg, 97078 Würzburg, Germany; Rudolf Virchow Center, DFG-Research Center for Experimental Biomedicine, University of Würzburg, 97078 Würzburg, Germany
| | - Davide Calebiro
- Institute of Pharmacology and Toxicology, University of Würzburg, 97078 Würzburg, Germany; Rudolf Virchow Center, DFG-Research Center for Experimental Biomedicine, University of Würzburg, 97078 Würzburg, Germany
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Kim B, Song HS, Jin HJ, Park EJ, Lee SH, Lee BY, Park TH, Hong S. Highly selective and sensitive detection of neurotransmitters using receptor-modified single-walled carbon nanotube sensors. NANOTECHNOLOGY 2013; 24:285501. [PMID: 23792421 DOI: 10.1088/0957-4484/24/28/285501] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We present receptor-modified carbon nanotube sensors for the highly selective and sensitive detection of acetylcholine (ACh), one kind of neurotransmitter. Here, we successfully expressed the M1 muscarinic acetylcholine receptor (M1 mAChR), a family of G protein-coupled receptors (GPCRs), in E. coli and coated single-walled carbon nanotube (swCNT)-field effect transistors (FETs) with lipid membrane including the receptor, enabling highly selective and sensitive ACh detection. Using this sensor, we could detect ACh at 100 pM concentration. Moreover, we showed that this sensor could selectively detect ACh among other neurotransmitters. This is the first demonstration of the real-time detection of ACh using specific binding between ACh and M1 mAChR, and it may lead to breakthroughs for various applications such as disease diagnosis and drug screening.
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Affiliation(s)
- Byeongju Kim
- Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
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Ward RJ, Milligan G. Structural and biophysical characterisation of G protein-coupled receptor ligand binding using resonance energy transfer and fluorescent labelling techniques. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:3-14. [PMID: 23590995 DOI: 10.1016/j.bbamem.2013.04.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 03/22/2013] [Accepted: 04/07/2013] [Indexed: 11/29/2022]
Abstract
The interaction between ligands and the G protein-coupled receptors (GPCRs) to which they bind has long been the focus of intensive investigation. The signalling cascades triggered by receptor activation, due in most cases to ligand binding, are of great physiological and medical importance; indeed, GPCRs are targeted by in excess of 30% of small molecule therapeutic medicines. Attempts to identify further pharmacologically useful GPCR ligands, for receptors with known and unknown endogenous ligands, continue apace. In earlier days direct assessment of such interactions was restricted largely to the use of ligands incorporating radioactive isotope labels as this allowed detection of the ligand and monitoring its interaction with the GPCR. This use of such markers has continued with the development of ligands labelled with fluorophores and their application to the study of receptor-ligand interactions using both light microscopy and resonance energy transfer techniques, including homogenous time-resolved fluorescence resonance energy transfer. Details of ligand-receptor interactions via X-ray crystallography are advancing rapidly as methods suitable for routine production of substantial amounts and stabilised forms of GPCRs have been developed and there is hope that this may become as routine as the co-crystallisation of serine/threonine kinases with ligands, an approach that has facilitated widespread use of rapid structure-based ligand design. Conformational changes involved in the activation of GPCRs, widely predicted by biochemical and biophysical means, have inspired the development of intramolecular FRET-based sensor forms of GPCRs designed to investigate the events following ligand binding and resulting in a signal propagation across the cell membrane. Finally, a number of techniques are emerging in which ligand-GPCR binding can be studied in ways that, whilst indirect, are able to monitor its results in an unbiased and integrated manner. This article is part of a Special Issue entitled: Structural and biophysical characterisation of membrane protein-ligand binding.
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Affiliation(s)
- Richard J Ward
- Molecular Pharmacology Group, Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
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40
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Bock A, Merten N, Schrage R, Dallanoce C, Bätz J, Klöckner J, Schmitz J, Matera C, Simon K, Kebig A, Peters L, Müller A, Schrobang-Ley J, Tränkle C, Hoffmann C, De Amici M, Holzgrabe U, Kostenis E, Mohr K. The allosteric vestibule of a seven transmembrane helical receptor controls G-protein coupling. Nat Commun 2013; 3:1044. [PMID: 22948826 PMCID: PMC3658004 DOI: 10.1038/ncomms2028] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 07/30/2012] [Indexed: 12/16/2022] Open
Abstract
Seven transmembrane helical receptors (7TMRs) modulate cell function via different types of G proteins, often in a ligand-specific manner. Class A 7TMRs harbour allosteric vestibules in the entrance of their ligand-binding cavities, which are in the focus of current drug discovery. However, their biological function remains enigmatic. Here we present a new strategy for probing and manipulating conformational transitions in the allosteric vestibule of label-free 7TMRs using the M2 acetylcholine receptor as a paradigm. We designed dualsteric agonists as 'tailor-made' chemical probes to trigger graded receptor activation from the acetylcholine-binding site while simultaneously restricting spatial flexibility of the receptor's allosteric vestibule. Our findings reveal for the first time that a 7TMR's allosteric vestibule controls the extent of receptor movement to govern a hierarchical order of G-protein coupling. This is a new concept assigning a biological role to the allosteric vestibule for controlling fidelity of 7TMR signalling. Class A seven transmembrane helical receptors harbour vestibules at the entrance to the ligand-binding domain. Here, Bock et al. use probes to monitor the conformation of the M2 muscarinic receptor and show that the vestibule alters the extent of receptor movement.
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Affiliation(s)
- Andreas Bock
- Pharmacology and Toxicology Section, Institute of Pharmacy, University of Bonn, Gerhard-Domagk-Straße 3, 53121 Bonn, Germany
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41
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Vilardaga JP, Romero G, Feinstein TN, Wehbi VL. Kinetics and dynamics in the G protein-coupled receptor signaling cascade. Methods Enzymol 2013; 522:337-63. [PMID: 23374192 DOI: 10.1016/b978-0-12-407865-9.00016-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We describe optical and microscopy methods based on Förster resonance energy transfer, fluorescence recovery after photobleaching, and imaging cross-correlation spectroscopy that permit to determine kinetic and dynamic properties of key reactions involved G protein-coupled receptor (GPCR) signaling from the initial ligand binding step to the generation of the second messenger, cAMP. Well suited to determine rate-limiting reactions taking place along a GPCR signaling cascade in live cells, these techniques have also uncovered new concepts in GPCR signaling as well as many interesting mechanistic subtleties by which GPCRs transmit neurotransmitter and hormone signals into cells.
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Affiliation(s)
- Jean-Pierre Vilardaga
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA.
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42
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Lane JR, Canals M. Sequential conformational rearrangements dictate the dynamics of class C GPCR activation. Sci Signal 2012; 5:pe51. [PMID: 23169816 DOI: 10.1126/scisignal.2003503] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Heterotrimeric GTP-binding protein (G protein)-coupled receptors (GPCRs) are the largest family of cell surface receptors; they allow cells to respond to a wide range of endogenous and environmental signals. Class C GPCRs represent a discrete group within the GPCR family, with distinct structural characteristics. Receptors belonging to this class--such as γ-aminobutyric acid type B (GABA(B)) receptors or metabotropic glutamate receptors (mGluRs)--form constitutive dimers. However, the conformational changes within such a dimeric receptor that are associated with agonist activation are still not well understood. A study by Hlavackova et al. investigates the role of dimer formation in mGluR1 activation. Using fluorescence resonance energy transfer approaches to assess inter- and intrasubunit conformational changes, the authors present an elegant study that sheds light on the kinetics of domain rearrangements in a class C GPCR upon ligand binding.
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Affiliation(s)
- J Robert Lane
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia
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43
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Rebois RV, Maki K, Meeks JA, Fishman PH, Hébert TE, Northup JK. D2-like dopamine and β-adrenergic receptors form a signaling complex that integrates Gs- and Gi-mediated regulation of adenylyl cyclase. Cell Signal 2012; 24:2051-60. [PMID: 22759790 PMCID: PMC3432756 DOI: 10.1016/j.cellsig.2012.06.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Revised: 06/13/2012] [Accepted: 06/22/2012] [Indexed: 12/20/2022]
Abstract
β-Adrenergic receptors (βAR) and D(2)-like dopamine receptors (which include D(2)-, D(3)- and D(4)-dopamine receptors) activate G(s) and G(i), the stimulatory and inhibitory heterotrimeric G proteins, respectively, which in turn regulate the activity of adenylyl cyclase (AC). β(2)-Adrenergic receptors (β(2)AR) and D(4)-dopamine receptors (D(4)DR) co-immunoprecipitated when co-expressed in HEK 293 cells, suggesting the existence of a signaling complex containing both receptors. In order to determine if these receptors are closely associated with each other, and with other components involved in G protein-mediated signal transduction, β(2)AR, D(4)DR, G protein subunits (Gα(i1) and the Gβ(1)γ(2) heterodimer) and AC were tagged so that bioluminescence resonance energy transfer (BRET) could be used to monitor their interactions. All of the tagged proteins retained biological function. For the first time, FlAsH-labeled proteins were used in BRET experiments as fluorescent acceptors for the energy transferred from Renilla luciferase-tagged donor proteins. Our experiments revealed that β(2)AR, D(4)DR, G proteins and AC were closely associated in a functional signaling complex in cellulo. Furthermore, BRET experiments indicated that although activation of G(i) caused a conformational change within the heterotrimeric protein, it did not cause the Gβγ heterodimer to dissociate from the Gα(i1) subunit. Evidence for the presence of a signaling complex in vivo was obtained by purifying βAR from detergent extracts of mouse brain with alprenolol-Sepharose and showing that the precipitate also contained both D(2)-like dopamine receptors and AC.
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Affiliation(s)
- R Victor Rebois
- Laboratory of Cellular Biology, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, United States.
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Hlavackova V, Zabel U, Frankova D, Bätz J, Hoffmann C, Prezeau L, Pin JP, Blahos J, Lohse MJ. Sequential inter- and intrasubunit rearrangements during activation of dimeric metabotropic glutamate receptor 1. Sci Signal 2012; 5:ra59. [PMID: 22894836 DOI: 10.1126/scisignal.2002720] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The metabotropic glutamate receptor 1 (mGluR1), a class C member of the heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptor family, is a constitutive dimer that regulates excitatory neurotransmission. We investigated the role of homodimer formation in mGluR1 activation by examining activation-dependent inter- and intrasubunit conformational changes by fluorescence resonance energy transfer (FRET). We inserted yellow and cyan fluorescent proteins in the second intracellular loop and at the carboxyl terminus of mGluR1 to act as FRET sensors and expressed these proteins in human embryonic kidney 293 cells. Agonist-dependent activation of these mGluR1 chimeras rapidly increased the intersubunit FRET, suggesting rapid movement of the subunits relative to each other. After intersubunit movement, the intrasubunit FRET decreased, reflecting conformational changes within a subunit. Cotransfection of chimeric receptor subunits that were capable or incapable of G protein coupling revealed that only a single subunit assumes an active state in an mGluR1 receptor dimer.
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Affiliation(s)
- Veronika Hlavackova
- Institute of Pharmacology and Toxicology, University of Würzburg, 97078 Würzburg, Germany
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45
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Hoffmann C, Nuber S, Zabel U, Ziegler N, Winkler C, Hein P, Berlot CH, Bünemann M, Lohse MJ. Comparison of the activation kinetics of the M3 acetylcholine receptor and a constitutively active mutant receptor in living cells. Mol Pharmacol 2012; 82:236-45. [PMID: 22564786 PMCID: PMC11037427 DOI: 10.1124/mol.112.077578] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Accepted: 05/07/2012] [Indexed: 12/26/2022] Open
Abstract
Activation of G-protein-coupled receptors is the first step of the signaling cascade triggered by binding of an agonist. Here we compare the activation kinetics of the G(q)-coupled M(3) acetylcholine receptor (M(3)-AChR) with that of a constitutively active mutant receptor (M(3)-AChR-N514Y) using M(3)-AChR constructs that report receptor activation by changes in the fluorescence resonance energy transfer (FRET) signal. We observed a leftward shift in the concentration-dependent FRET response for acetylcholine and carbachol with M(3)-AChR-N514Y. Consistent with this result, at submaximal agonist concentrations, the activation kinetics of M(3)-AChR-N514Y were significantly faster, whereas at maximal agonist concentrations the kinetics of receptor activation were identical. Receptor deactivation was significantly faster with carbachol than with acetylcholine and was significantly delayed by the N514Y mutation. Receptor-G-protein interaction was measured by FRET between M(3)-AChR-yellow fluorescent protein (YFP) and cyan fluorescent protein (CFP)-Gγ(2). Agonist-induced receptor-G-protein coupling was of a time scale similar to that of receptor activation. As observed for receptor deactivation, receptor-G-protein dissociation was slower for acetylcholine than that for carbachol. Acetylcholine-stimulated increases in receptor-G-protein coupling of M(3)-AChR-N514Y reached only 12% of that of M(3)-AChR and thus cannot be kinetically analyzed. G-protein activation was measured using YFP-tagged Gα(q) and CFP-tagged Gγ(2). Activation of G(q) was significantly slower than receptor activation and indistinguishable for the two agonists. However, G(q) deactivation was significantly prolonged for acetylcholine compared with that for carbachol. Consistent with decreased agonist-stimulated coupling to G(q), agonist-stimulated G(q) activation by M(3)-AChR-N514Y was not detected. Taken together, these results indicate that the N514Y mutation produces constitutive activation of M(3)-AChR by decreasing the rate of receptor deactivation, while having minimal effect on receptor activation.
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Affiliation(s)
- Carsten Hoffmann
- Department of Pharmacology and Toxicology, University of Wuerzburg, Versbacher Strasse 9, Wuerzburg, Germany.
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Lohse MJ, Nuber S, Hoffmann C. Fluorescence/bioluminescence resonance energy transfer techniques to study G-protein-coupled receptor activation and signaling. Pharmacol Rev 2012; 64:299-336. [PMID: 22407612 DOI: 10.1124/pr.110.004309] [Citation(s) in RCA: 251] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Fluorescence and bioluminescence resonance energy transfer (FRET and BRET) techniques allow the sensitive monitoring of distances between two labels at the nanometer scale. Depending on the placement of the labels, this permits the analysis of conformational changes within a single protein (for example of a receptor) or the monitoring of protein-protein interactions (for example, between receptors and G-protein subunits). Over the past decade, numerous such techniques have been developed to monitor the activation and signaling of G-protein-coupled receptors (GPCRs) in both the purified, reconstituted state and in intact cells. These techniques span the entire spectrum from ligand binding to the receptors down to intracellular second messengers. They allow the determination and the visualization of signaling processes with high temporal and spatial resolution. With these techniques, it has been demonstrated that GPCR signals may show spatial and temporal patterning. In particular, evidence has been provided for spatial compartmentalization of GPCRs and their signals in intact cells and for distinct physiological consequences of such spatial patterning. We review here the FRET and BRET technologies that have been developed for G-protein-coupled receptors and their signaling proteins (G-proteins, effectors) and the concepts that result from such experiments.
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Affiliation(s)
- Martin J Lohse
- Institute of Pharmacology and Toxicology, Versbacher Str. 9, 97078 Würzburg, Germany.
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47
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Xu TR, Ward RJ, Pediani JD, Milligan G. Intramolecular fluorescence resonance energy transfer (FRET) sensors of the orexin OX1 and OX2 receptors identify slow kinetics of agonist activation. J Biol Chem 2012; 287:14937-49. [PMID: 22389503 DOI: 10.1074/jbc.m111.334300] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Intramolecular fluorescence resonance energy transfer (FRET) sensors able to detect changes in distance or orientation between the 3rd intracellular loop and C-terminal tail of the human orexin OX(1) and OX(2) G protein-coupled receptors following binding of agonist ligands were produced and expressed stably. These were directed to the plasma membrane and, despite the substantial sequence alterations introduced, in each case were able to elevate [Ca(2+)](i), promote phosphorylation of the ERK1/2 MAP kinases and become internalized effectively upon addition of the native orexin peptides. Detailed characterization of the OX(1) sensor demonstrated that it was activated with rank order of potency orexin A > orexin B > orexin A 16-33, that it bound antagonist ligands with affinity similar to the wild-type receptor, and that mutation of a single residue, D203A, greatly reduced the binding and function of orexin A but not antagonist ligands. Addition of orexin A to individual cells expressing an OX(1) sensor resulted in a time- and concentration-dependent reduction in FRET signal consistent with mass-action and potency/affinity estimates for the peptide. Compared with the response kinetics of a muscarinic M(3) acetylcholine receptor sensor upon addition of agonist, response of the OX(1) and OX(2) sensors to orexin A was slow, consistent with a multistep binding and activation process. Such sensors provide means to assess the kinetics of receptor activation and how this may be altered by mutation and sequence variation of the receptors.
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Affiliation(s)
- Tian-Rui Xu
- Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
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Ambrosio M, Lohse MJ. Nonequilibrium activation of a G-protein-coupled receptor. Mol Pharmacol 2012; 81:770-7. [PMID: 22379120 DOI: 10.1124/mol.112.077693] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
G-protein-coupled receptor activation is generally analyzed under equilibrium conditions. However, real-life receptor functions are often dependent on very short, transient stimuli that may not allow the achievement of a steady state. This is particularly true for synaptic receptors such as the α(2A)-adrenergic receptor (α(2A)-AR). Therefore, we developed a fluorescence resonance energy transfer-based technology to study nonequilibrium α(2A)-AR function in living cells. To examine the effects of increasing concentrations of the endogenous agonist norepinephrine on the speed and extent of α(2A)-AR activation with very high temporal resolution, we took advantage of a fluorophore-containing α(2A)-AR sensor. The results indicated that the efficacy of norepinephrine in eliciting receptor activation increased in a time-dependent way, reaching the maximum with a half-life of ~60 ms. The EC(50) values under nonequilibrium conditions start at ~26 μM (at 40 ms) and show a 10-fold decrease until the steady state is achieved. To analyze the ability of norepinephrine to trigger a downstream intracellular response after α(2A)-AR stimulation, we monitored the kinetics and amplitude of G(i) activation in real time by using a fluorophore-containing G(i) sensor. The results show that both the efficacy and the potency of norepinephrine in inducing G(i) activation achieve a steady state more slowly, compared with receptor activation, and that the initial EC(50) value of ~100 nM decreases in an exponential way, reaching the minimal value of ~10 nM at equilibrium. Therefore, both the efficacy and the potency of norepinephrine increase ~10-fold over a few seconds of agonist stimulation, which illustrates that receptor and G-protein signaling and signal amplification are highly time-dependent phenomena.
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Affiliation(s)
- Manuela Ambrosio
- Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
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Detection of SNARE complexes with FRET using the tetracysteine system. Biotechniques 2012; 52:103-8. [DOI: 10.2144/000113811] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 12/30/2011] [Indexed: 11/23/2022] Open
Abstract
The three proteins synaptosomal-associated protein 25 (SNAP-25), Syntaxin-1a and vesicle-associated membrane protein (VAMP-2) are collectively called SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors). By assembling into an exocytic complex, the three SNAREs help in catalyzing membrane fusion. Due to lack of probes that adequately reconstitute the intracellular behavior of endogenous SNAREs, the dynamics of SNARE complexes in living cells is poorly understood. Here we describe a new FRET-based probe, called Cerulean-SNAP-25-C4 (CSNAC), that can track the conformational changes undergone by SNAP-25 as exocytic complexes assemble. The fluorescent protein Cerulean was attached to the N terminus and served as a FRET donor. The biarsenical dye FlAsH served as a FRET acceptor and was attached to a short tetracysteine motif (C4) motif inserted into the so-called linker domain of SNAP-25. CSNAC reported successive FRET changes when first Syntaxin-1a and then VAMP-2 were added in vitro. Small tetracysteine insertions used as a FRET acceptor are expected to have less steric hindrance than previously used GFP-based fluorophores. We propose that genetically-encoded tetracysteine tags can be used to study regulated SNARE complex assembly in vivo.
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50
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Prakash A, Luthra PM. Insilico study of the A2AR–D2R kinetics and interfacial contact surface for heteromerization. Amino Acids 2012; 43:1451-64. [DOI: 10.1007/s00726-012-1218-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Accepted: 01/04/2012] [Indexed: 12/28/2022]
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