1
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Solis GP, Koval A, Valnohova J, Kazemzadeh A, Savitsky M, Katanaev VL. Neomorphic Gαo mutations gain interaction with Ric8 proteins in GNAO1 encephalopathies. J Clin Invest 2024; 134:e172057. [PMID: 38874642 PMCID: PMC11291268 DOI: 10.1172/jci172057] [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: 05/15/2023] [Accepted: 06/04/2024] [Indexed: 06/15/2024] Open
Abstract
GNAO1 mutated in pediatric encephalopathies encodes the major neuronal G protein Gαo. Of the more than 80 pathogenic mutations, most are single amino acid substitutions spreading across the Gαo sequence. We performed extensive characterization of Gαo mutants, showing abnormal GTP uptake and hydrolysis and deficiencies in binding Gβγ and RGS19. Plasma membrane localization of Gαo was decreased for a subset of mutations that leads to epilepsy; dominant interactions with GPCRs also emerged for the more severe mutants. Pathogenic mutants massively gained interaction with Ric8A and, surprisingly, Ric8B proteins, relocalizing them from cytoplasm to Golgi. Of these 2 mandatory Gα-subunit chaperones, Ric8A is normally responsible for the Gαi/Gαo, Gαq, and Gα12/Gα13 subfamilies, and Ric8B solely responsible for Gαs/Gαolf. Ric8 mediates the disease dominance when engaging in neomorphic interactions with pathogenic Gαo through imbalance of the neuronal G protein signaling networks. As the strength of Gαo-Ric8B interactions correlates with disease severity, our study further identifies an efficient biomarker and predictor for clinical manifestations in GNAO1 encephalopathies. Our work uncovers the neomorphic molecular mechanism of mutations underlying pediatric encephalopathies and offers insights into other maladies caused by G protein malfunctioning and further genetic diseases.
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Affiliation(s)
- Gonzalo P. Solis
- Translational Research Center in Oncohaematology, Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Alexey Koval
- Translational Research Center in Oncohaematology, Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Jana Valnohova
- Translational Research Center in Oncohaematology, Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Arghavan Kazemzadeh
- Translational Research Center in Oncohaematology, Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Mikhail Savitsky
- Translational Research Center in Oncohaematology, Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Vladimir L. Katanaev
- Translational Research Center in Oncohaematology, Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
- School of Medicine and Life Sciences, Department of Pharmacy and Pharmacology, Far Eastern Federal University, Vladivostok, Russia
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2
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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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3
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Calderón JC, Ibrahim P, Gobbo D, Gervasio FL, Clark T. Activation/Deactivation Free-Energy Profiles for the β 2-Adrenergic Receptor: Ligand Modes of Action. J Chem Inf Model 2023; 63:6332-6343. [PMID: 37824365 DOI: 10.1021/acs.jcim.3c00805] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2023]
Abstract
We use enhanced-sampling simulations with an effective collective variable to study the activation of the β2-adrenergic receptor in the presence of ligands with different efficacy. The free-energy profiles are computed for the ligand-free (apo) receptor and binary (apo-receptor + G-protein α-subunit and receptor + ligand) and ternary complexes. The results are not only compatible with available experiments but also allow unprecedented structural insight into the nature of GPCR conformations along the activation pathway and their role in the activation mechanism. In particular, the simulations reveal an unexpected mode of action of partial agonists such as salmeterol and salbutamol that arises already in the binary complex without the G-protein. Specific differences in the polar interactions with residues in TM5, which are required to stabilize an optimal TM6 conformation that facilitates G-protein binding and receptor activation, play a major role in differentiating them from full agonists.
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Affiliation(s)
- Jacqueline C Calderón
- Computer-Chemistry-Center, Department of Chemistry and Pharmacy, Friedrich-Alexander-University Erlangen-Nuernberg, Naegelsbachstraße 25, 91052 Erlangen, Germany
| | - Passainte Ibrahim
- Institute of Medical Physics and Biophysics, Faculty of Medicine, University of Leipzig, 04109 Leipzig, Germany
| | - Dorothea Gobbo
- Pharmaceutical Sciences, University of Geneva, CH1206 Geneva, Switzerland
- Institute of Pharmaceutical Sciences of Western Switzerland, CH1206 Geneva, Switzerland
| | - Francesco Luigi Gervasio
- Pharmaceutical Sciences, University of Geneva, CH1206 Geneva, Switzerland
- Institute of Pharmaceutical Sciences of Western Switzerland, CH1206 Geneva, Switzerland
- Chemistry Department, University College London, WC1H 0AJ London, United Kingdom
- Swiss Bioinformatics Institute, CH1206 Geneva, Switzerland
| | - Timothy Clark
- Computer-Chemistry-Center, Department of Chemistry and Pharmacy, Friedrich-Alexander-University Erlangen-Nuernberg, Naegelsbachstraße 25, 91052 Erlangen, Germany
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4
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Xu J, Wang Q, Hübner H, Hu Y, Niu X, Wang H, Maeda S, Inoue A, Tao Y, Gmeiner P, Du Y, Jin C, Kobilka BK. Structural and dynamic insights into supra-physiological activation and allosteric modulation of a muscarinic acetylcholine receptor. Nat Commun 2023; 14:376. [PMID: 36690613 PMCID: PMC9870890 DOI: 10.1038/s41467-022-35726-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Accepted: 12/21/2022] [Indexed: 01/25/2023] Open
Abstract
The M2 muscarinic receptor (M2R) is a prototypical G-protein-coupled receptor (GPCR) that serves as a model system for understanding GPCR regulation by both orthosteric and allosteric ligands. Here, we investigate the mechanisms governing M2R signaling versatility using cryo-electron microscopy (cryo-EM) and NMR spectroscopy, focusing on the physiological agonist acetylcholine and a supra-physiological agonist iperoxo, as well as a positive allosteric modulator LY2119620. These studies reveal that acetylcholine stabilizes a more heterogeneous M2R-G-protein complex than iperoxo, where two conformers with distinctive G-protein orientations were determined. We find that LY2119620 increases the affinity for both agonists, but differentially modulates agonists efficacy in G-protein and β-arrestin pathways. Structural and spectroscopic analysis suggest that LY211620 stabilizes distinct intracellular conformational ensembles from agonist-bound M2R, which may enhance β-arrestin recruitment while impairing G-protein activation. These results highlight the role of conformational dynamics in the complex signaling behavior of GPCRs, and could facilitate design of better drugs.
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Affiliation(s)
- Jun Xu
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, 94305, USA
- Beijing Advanced Innovation Center for Structural Biology, School of Medicine, Tsinghua University, 100084, Beijing, China
| | - Qinggong Wang
- Kobilka Institute of Innovative Drug Discovery, School of Life and Health Sciences, Chinese University of Hong Kong, 518172, Shenzhen, China
- Division of Life Sciences and Medicine, University of Science and Technology of China, 230027, Hefei, P. R. China
| | - Harald Hübner
- Department of Chemistry and Pharmacy, Medicinal Chemistry, Friedrich-Alexander University, 91058, Erlangen, Germany
| | - Yunfei Hu
- Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, Peking University, 100084, Beijing, China
- Innovation Academy for Precision Measurement Science and Technology, CAS, 430071, Wuhan, China
| | - Xiaogang Niu
- Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, Peking University, 100084, Beijing, China
| | - Haoqing Wang
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Shoji Maeda
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, 94305, USA
- Department of Pharmacology, Medical School, University of Michigan 1150 Medical Center Dr., 1315 Medical Science Research Bldg III, Ann Arbor, MI, 48109, USA
| | - Asuka Inoue
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, 980-8578, Japan
| | - Yuyong Tao
- Division of Life Sciences and Medicine, University of Science and Technology of China, 230027, Hefei, P. R. China
| | - Peter Gmeiner
- Department of Chemistry and Pharmacy, Medicinal Chemistry, Friedrich-Alexander University, 91058, Erlangen, Germany
| | - Yang Du
- Kobilka Institute of Innovative Drug Discovery, School of Life and Health Sciences, Chinese University of Hong Kong, 518172, Shenzhen, China.
| | - Changwen Jin
- Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, Peking University, 100084, Beijing, China.
| | - Brian K Kobilka
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, 94305, USA.
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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] [Key Words] [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
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6
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Aslanoglou D, Bertera S, Friggeri L, Sánchez-Soto M, Lee J, Xue X, Logan RW, Lane JR, Yechoor VK, McCormick PJ, Meiler J, Free RB, Sibley DR, Bottino R, Freyberg Z. Dual pancreatic adrenergic and dopaminergic signaling as a therapeutic target of bromocriptine. iScience 2022; 25:104771. [PMID: 35982797 PMCID: PMC9379584 DOI: 10.1016/j.isci.2022.104771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 06/10/2022] [Accepted: 07/11/2022] [Indexed: 11/23/2022] Open
Abstract
Bromocriptine is approved as a diabetes therapy, yet its therapeutic mechanisms remain unclear. Though bromocriptine's actions have been mainly attributed to the stimulation of brain dopamine D2 receptors (D2R), bromocriptine also targets the pancreas. Here, we employ bromocriptine as a tool to elucidate the roles of catecholamine signaling in regulating pancreatic hormone secretion. In β-cells, bromocriptine acts on D2R and α2A-adrenergic receptor (α2A-AR) to reduce glucose-stimulated insulin secretion (GSIS). Moreover, in α-cells, bromocriptine acts via D2R to reduce glucagon secretion. α2A-AR activation by bromocriptine recruits an ensemble of G proteins with no β-arrestin2 recruitment. In contrast, D2R recruits G proteins and β-arrestin2 upon bromocriptine stimulation, demonstrating receptor-specific signaling. Docking studies reveal distinct bromocriptine binding to α2A-AR versus D2R, providing a structural basis for bromocriptine's dual actions on β-cell α2A-AR and D2R. Together, joint dopaminergic and adrenergic receptor actions on α-cell and β-cell hormone release provide a new therapeutic mechanism to improve dysglycemia.
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Affiliation(s)
- Despoina Aslanoglou
- Translational Neuroscience Program, Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Suzanne Bertera
- Institute of Cellular Therapeutics, Allegheny Health Network Research Institute, Allegheny Health Network, Pittsburgh, PA, USA
| | - Laura Friggeri
- Department of Chemistry, Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Marta Sánchez-Soto
- Molecular Neuropharmacology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Jeongkyung Lee
- Diabetes and Beta Cell Biology Center, Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Xiangning Xue
- Department of Biostatistics, University of Pittsburgh, Pittsburgh, PA, USA
| | - Ryan W. Logan
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, USA
| | - J. Robert Lane
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen’s Medical Centre, University of Nottingham, Nottingham, UK
- Centre of Membrane Protein and Receptors, Universities of Birmingham and Nottingham, Nottingham, UK
| | - Vijay K. Yechoor
- Diabetes and Beta Cell Biology Center, Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Peter J. McCormick
- Centre for Endocrinology, William Harvey Research Institute, Bart’s and the London School of Medicine and Dentistry, Queen Mary, University of London, London, UK
| | - Jens Meiler
- Department of Chemistry, Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
- Institute for Drug Discovery, Leipzig University Medical School, Leipzig, Germany
| | - R. Benjamin Free
- Molecular Neuropharmacology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - David R. Sibley
- Molecular Neuropharmacology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Rita Bottino
- Institute of Cellular Therapeutics, Allegheny Health Network Research Institute, Allegheny Health Network, Pittsburgh, PA, USA
- Imagine Pharma, Pittsburgh, PA, USA
| | - Zachary Freyberg
- Translational Neuroscience Program, Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Cell Biology, University of Pittsburgh, PA, USA
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7
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Xu J, Cao S, Hübner H, Weikert D, Chen G, Lu Q, Yuan D, Gmeiner P, Liu Z, Du Y. Structural insights into ligand recognition, activation, and signaling of the α 2A adrenergic receptor. SCIENCE ADVANCES 2022; 8:eabj5347. [PMID: 35245122 PMCID: PMC8896805 DOI: 10.1126/sciadv.abj5347] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The α2A adrenergic receptor (α2AAR) is a G protein (heterotrimeric guanine nucleotide-binding protein)-coupled receptor that mediates important physiological functions in response to the endogenous neurotransmitters norepinephrine and epinephrine, as well as numerous chemically distinct drugs. However, the molecular mechanisms of drug actions remain poorly understood. Here, we report the cryo-electron microscopy structures of the human α2AAR-GoA complex bound to norepinephrine and three imidazoline derivatives (brimonidine, dexmedetomidine, and oxymetazoline). Together with mutagenesis and functional data, these structures provide important insights into the molecular basis of ligand recognition, activation, and signaling at the α2AAR. Further structural analyses uncover different molecular determinants between α2AAR and βARs for recognition of norepinephrine and key regions that determine the G protein coupling selectivity. Overall, our studies provide a framework for understanding the signal transduction of the adrenergic system at the atomic level, which will facilitate rational structure-based discovery of safer and more effective medications for α2AAR.
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Affiliation(s)
- Jun Xu
- Kobilka Institute of Innovative Drug Discovery, School of Life and Health Sciences, Chinese University of Hong Kong, Shenzhen, 518172, China
| | - Sheng Cao
- Kobilka Institute of Innovative Drug Discovery, School of Life and Health Sciences, Chinese University of Hong Kong, Shenzhen, 518172, China
| | - Harald Hübner
- Department of Chemistry and Pharmacy, Medicinal Chemistry, Friedrich-Alexander University, Nikolaus-Fiebiger-Straße 10, 91058 Erlangen, Germany
| | - Dorothée Weikert
- Department of Chemistry and Pharmacy, Medicinal Chemistry, Friedrich-Alexander University, Nikolaus-Fiebiger-Straße 10, 91058 Erlangen, Germany
| | - Geng Chen
- Kobilka Institute of Innovative Drug Discovery, School of Life and Health Sciences, Chinese University of Hong Kong, Shenzhen, 518172, China
| | - Qiuyuan Lu
- Kobilka Institute of Innovative Drug Discovery, School of Life and Health Sciences, Chinese University of Hong Kong, Shenzhen, 518172, China
| | - Daopeng Yuan
- Beijing Advanced Innovation Center for Structural Biology, School of Medicine, Tsinghua University, Beijing 100084, China
- Corresponding author. (D.Y.); (P.G.); (Z.L.); (Y.D.)
| | - Peter Gmeiner
- Department of Chemistry and Pharmacy, Medicinal Chemistry, Friedrich-Alexander University, Nikolaus-Fiebiger-Straße 10, 91058 Erlangen, Germany
- Corresponding author. (D.Y.); (P.G.); (Z.L.); (Y.D.)
| | - Zheng Liu
- Kobilka Institute of Innovative Drug Discovery, School of Life and Health Sciences, Chinese University of Hong Kong, Shenzhen, 518172, China
- Corresponding author. (D.Y.); (P.G.); (Z.L.); (Y.D.)
| | - Yang Du
- Kobilka Institute of Innovative Drug Discovery, School of Life and Health Sciences, Chinese University of Hong Kong, Shenzhen, 518172, China
- Corresponding author. (D.Y.); (P.G.); (Z.L.); (Y.D.)
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8
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Hilger D. The role of structural dynamics in GPCR‐mediated signaling. FEBS J 2021; 288:2461-2489. [DOI: 10.1111/febs.15841] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 03/19/2021] [Accepted: 03/24/2021] [Indexed: 12/18/2022]
Affiliation(s)
- Daniel Hilger
- Department of Pharmaceutical Chemistry Philipps‐University Marburg Germany
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9
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Dopamine D 2 Receptor Agonist Binding Kinetics-Role of a Conserved Serine Residue. Int J Mol Sci 2021; 22:ijms22084078. [PMID: 33920848 PMCID: PMC8071183 DOI: 10.3390/ijms22084078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/06/2021] [Accepted: 04/13/2021] [Indexed: 01/03/2023] Open
Abstract
The forward (kon) and reverse (koff) rate constants of drug–target interactions have important implications for therapeutic efficacy. Hence, time-resolved assays capable of measuring these binding rate constants may be informative to drug discovery efforts. Here, we used an ion channel activation assay to estimate the kons and koffs of four dopamine D2 receptor (D2R) agonists; dopamine (DA), p-tyramine, (R)- and (S)-5-OH-dipropylaminotetralin (DPAT). We further probed the role of the conserved serine S1935.42 by mutagenesis, taking advantage of the preferential interaction of (S)-, but not (R)-5-OH-DPAT with this residue. Results suggested similar koffs for the two 5-OH-DPAT enantiomers at wild-type (WT) D2R, both being slower than the koffs of DA and p-tyramine. Conversely, the kon of (S)-5-OH-DPAT was estimated to be higher than that of (R)-5-OH-DPAT, in agreement with the higher potency of the (S)-enantiomer. Furthermore, S1935.42A mutation lowered the kon of (S)-5-OH-DPAT and reduced the potency difference between the two 5-OH-DPAT enantiomers. Kinetic Kds derived from the koff and kon estimates correlated well with EC50 values for all four compounds across four orders of magnitude, strengthening the notion that our assay captured meaningful information about binding kinetics. The approach presented here may thus prove valuable for characterizing D2R agonist candidate drugs.
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10
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Deconvolution of WNT-induced Frizzled conformational dynamics with fluorescent biosensors. Biosens Bioelectron 2020; 177:112948. [PMID: 33486136 DOI: 10.1016/j.bios.2020.112948] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 12/25/2020] [Indexed: 02/07/2023]
Abstract
The G protein-coupled receptors Frizzled1-10 (FZD1-10) act as molecular checkpoints mediating intracellular signaling induced by 19 mammalian, secreted Wingless/Int-1 lipoglycoproteins (WNTs). Despite the vital roles of these signaling components in health and disease, our knowledge about WNT/FZD selectivity, and the mechanisms of receptor activation and intracellular signal propagation by individual ligand/receptor pairs is limited due to the current lack of suitable biophysical techniques. Here, we developed fluorescence-based biosensors that detect WNT-induced FZD conformational changes in living cells in order to assess WNT action via FZDs at the most proximal level, i.e. the receptor conformation. By testing a panel of recombinant ligands on conformational biosensors representing all four homology clusters of FZDs, we discover yet unappreciated selectivities of WNTs to their receptors and, surprisingly, identify distinct ligand-induced receptor conformations. Furthermore, we demonstrate that FZDs can undergo conformational changes upon WNT binding without being dependent on the WNT co-receptors LRP5/6. This sensor toolbox provides an advanced platform for a thorough investigation of the 190 possible WNT/FZD pairings and for future screening campaigns targeting synthetic FZD ligands. Furthermore, our findings shed new light on the complexity of the WNT/FZD signaling system and have substantial implications for our understanding of fundamental biological processes including embryonal development and tumorigenesis.
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11
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Schihada H, Ma X, Zabel U, Vischer HF, Schulte G, Leurs R, Pockes S, Lohse MJ. Development of a Conformational Histamine H 3 Receptor Biosensor for the Synchronous Screening of Agonists and Inverse Agonists. ACS Sens 2020; 5:1734-1742. [PMID: 32397705 PMCID: PMC7325232 DOI: 10.1021/acssensors.0c00397] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
![]()
The
histamine H3 receptor (H3R) represents
a highly attractive drug target for the treatment of various central
nervous system disorders, but the discovery of novel H3R targeting compounds relies on the assessment of highly amplified
intracellular signaling events that do not only reflect H3R modulation and carry the risk of high false-positive and -negative
screening rates. To address these limitations, we designed an intramolecular
H3R biosensor based on the principle of bioluminescence
resonance energy transfer (BRET) that reports the receptor’s
real-time conformational dynamics and provides an advanced tool to
screen for both H3R agonists and inverse agonists in a
live cell screening-compatible assay format. This conformational G-protein-coupled
receptor (GPCR) sensor allowed us to characterize the pharmacological
properties of known and new H3 receptor ligands with unprecedented
accuracy. Interestingly, we found that one newly developed H3 receptor ligand possesses even stronger inverse agonistic activity
than reference H3R inverse agonists including the current
gold standard pitolisant. Taken together, we describe here the design
and validation of the first screening-compatible H3R conformational
biosensor that will aid in the discovery of novel H3R ligands
and can be employed to gain deeper insights into the (in-)activation
mechanism of this highly attractive drug target.
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Affiliation(s)
- Hannes Schihada
- Section of Receptor Biology & Signaling, Dept. Physiology & Pharmacology, Karolinska Institutet, Stockholm 171 77, Sweden
- Institute of Pharmacology and Toxicology and Rudolf Virchow Center, University of Würzburg, Würzburg 97070, Germany
| | - Xiaoyuan Ma
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Science, Vrije Universiteit Amsterdam, Amsterdam 1081 HV, The Netherlands
| | - Ulrike Zabel
- Institute of Pharmacology and Toxicology and Rudolf Virchow Center, University of Würzburg, Würzburg 97070, Germany
| | - Henry F. Vischer
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Science, Vrije Universiteit Amsterdam, Amsterdam 1081 HV, The Netherlands
| | - Gunnar Schulte
- Section of Receptor Biology & Signaling, Dept. Physiology & Pharmacology, Karolinska Institutet, Stockholm 171 77, Sweden
| | - Rob Leurs
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Science, Vrije Universiteit Amsterdam, Amsterdam 1081 HV, The Netherlands
| | - Steffen Pockes
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Regensburg 93053, Germany
| | - Martin J. Lohse
- Institute of Pharmacology and Toxicology and Rudolf Virchow Center, University of Würzburg, Würzburg 97070, Germany
- ISAR Bioscience, Planegg 82152, Germany
- Max Delbrück Center for Molecular Medicine, Berlin 13125, Germany
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12
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Chang W, Tu CL, Jean-Alphonse FG, Herberger A, Cheng Z, Hwong J, Ho H, Li A, Wang D, Liu H, White AD, Suh I, Shen W, Duh QY, Khanafshar E, Shoback DM, Xiao K, Vilardaga JP. PTH hypersecretion triggered by a GABA B1 and Ca 2+-sensing receptor heterocomplex in hyperparathyroidism. Nat Metab 2020; 2:243-255. [PMID: 32694772 PMCID: PMC7377265 DOI: 10.1038/s42255-020-0175-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 01/20/2020] [Indexed: 12/14/2022]
Abstract
Molecular mechanisms mediating tonic secretion of parathyroid hormone (PTH) in response to hypocalcaemia and hyperparathyroidism (HPT) are unclear. Here we demonstrate increased heterocomplex formation between the calcium-sensing receptor (CaSR) and metabotropic γ-aminobutyric acid (GABA) B1 receptor (GABAB1R) in hyperplastic parathyroid glands (PTGs) of patients with primary and secondary HPT. Targeted ablation of GABAB1R or glutamic acid decarboxylase 1 and 2 in PTGs produces hypocalcaemia and hypoparathyroidism, and prevents PTH hypersecretion in PTGs cultured from mouse models of hereditary HPT and dietary calcium-deficiency. Cobinding of the CaSR/GABAB1R complex by baclofen and high extracellular calcium blocks the coupling of heterotrimeric G-proteins to homomeric CaSRs in cultured cells and promotes PTH secretion in cultured mouse PTGs. These results combined with the ability of PTG to synthesize GABA support a critical autocrine action of GABA/GABAB1R in mediating tonic PTH secretion of PTGs and ascribe aberrant activities of CaSR/GABAB1R heteromer to HPT.
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Affiliation(s)
- Wenhan Chang
- Endocrine Research Unit, Department of Veterans Affairs Medical Center, University of California, San Francisco, CA, USA.
| | - Chia-Ling Tu
- Endocrine Research Unit, Department of Veterans Affairs Medical Center, University of California, San Francisco, CA, USA
| | - Frederic G Jean-Alphonse
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Amanda Herberger
- Endocrine Research Unit, Department of Veterans Affairs Medical Center, University of California, San Francisco, CA, USA
| | - Zhiqiang Cheng
- Endocrine Research Unit, Department of Veterans Affairs Medical Center, University of California, San Francisco, CA, USA
| | - Jenna Hwong
- Endocrine Research Unit, Department of Veterans Affairs Medical Center, University of California, San Francisco, CA, USA
| | - Hanson Ho
- Endocrine Research Unit, Department of Veterans Affairs Medical Center, University of California, San Francisco, CA, USA
| | - Alfred Li
- Endocrine Research Unit, Department of Veterans Affairs Medical Center, University of California, San Francisco, CA, USA
| | - Dawei Wang
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Hongda Liu
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Alex D White
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Graduate Program in Molecular Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Insoo Suh
- Department of Surgery, University of California, San Francisco, CA, USA
| | - Wen Shen
- Department of Surgery, University of California, San Francisco, CA, USA
| | - Quan-Yang Duh
- Department of Surgery, University of California, San Francisco, CA, USA
| | - Elham Khanafshar
- Department of Pathology, University of California, San Francisco, CA, USA
| | - Dolores M Shoback
- Endocrine Research Unit, Department of Veterans Affairs Medical Center, University of California, San Francisco, CA, USA
| | - Kunhong Xiao
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Jean-Pierre Vilardaga
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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14
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Membrane lipid environment: Potential modulation of chemokine receptor function. Cytokine 2018; 109:72-75. [DOI: 10.1016/j.cyto.2018.02.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 01/18/2018] [Accepted: 02/05/2018] [Indexed: 01/23/2023]
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15
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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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16
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Abstract
In the past decade, automated microscopy has become an important tool for the drug discovery and development process. The establishment of imaging modalities as screening tools depended on technological breakthroughs in the domain of automated microscopy and automated image analysis. These types of assays are often referred to as high content screening or high content analysis (HCS/HCA). The driving force to adopt imaging for drug development is the quantity and quality of cellular information that can be collected and the enhanced physiological relevance of cellular screening compared to biochemical screening. Most imaging in drug development is performed on fixed cells as this allows uncoupling the preparation of the cells from the acquisition of the images. Live-cell imaging is technically challenging, but is very useful for many aspects of the drug development pipeline such as kinetic studies of compound mode of action or to analyze the motion of cellular components. Most vendors of HCS microscopy systems offer the option of environmental chambers and onboard pipetting on their platforms. This reflects the wish and desire of many customers to have the ability to perform live-cell assays on their HCS automated microscopes. This book chapter summarizes the challenges and advantages of live-cell imaging in drug discovery. Examples of applications are presented and the motivation to perform these assays in kinetic mode is discussed.
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Affiliation(s)
- Milan Esner
- High Throughput Technology Development Studio (HT-TDS), Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307, Dresden, Germany
- Department of Histology and Embryology, Faculty of Medicine, Masaryk University, Kamenice 3, 625 00, Brno, Czech Republic
| | - Felix Meyenhofer
- High Throughput Technology Development Studio (HT-TDS), Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307, Dresden, Germany
- Département de Médecine, Faculté des Sciences, University of Fribourg, 1, Rte., Albert Gockel, Fribourg, 1700, Switzerland
| | - Marc Bickle
- High Throughput Technology Development Studio (HT-TDS), Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307, Dresden, Germany.
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17
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Single-molecule imaging reveals receptor-G protein interactions at cell surface hot spots. Nature 2017; 550:543-547. [PMID: 29045395 DOI: 10.1038/nature24264] [Citation(s) in RCA: 198] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 09/08/2017] [Indexed: 12/19/2022]
Abstract
G-protein-coupled receptors mediate the biological effects of many hormones and neurotransmitters and are important pharmacological targets. They transmit their signals to the cell interior by interacting with G proteins. However, it is unclear how receptors and G proteins meet, interact and couple. Here we analyse the concerted motion of G-protein-coupled receptors and G proteins on the plasma membrane and provide a quantitative model that reveals the key factors that underlie the high spatiotemporal complexity of their interactions. Using two-colour, single-molecule imaging we visualize interactions between individual receptors and G proteins at the surface of living cells. Under basal conditions, receptors and G proteins form activity-dependent complexes that last for around one second. Agonists specifically regulate the kinetics of receptor-G protein interactions, mainly by increasing their association rate. We find hot spots on the plasma membrane, at least partially defined by the cytoskeleton and clathrin-coated pits, in which receptors and G proteins are confined and preferentially couple. Imaging with the nanobody Nb37 suggests that signalling by G-protein-coupled receptors occurs preferentially at these hot spots. These findings shed new light on the dynamic interactions that control G-protein-coupled receptor signalling.
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Benredjem B, Dallaire P, Pineyro G. Analyzing biased responses of GPCR ligands. Curr Opin Pharmacol 2017; 32:71-76. [DOI: 10.1016/j.coph.2016.11.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Revised: 11/11/2016] [Accepted: 11/18/2016] [Indexed: 10/20/2022]
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Scholler P, Moreno-Delgado D, Lecat-Guillet N, Doumazane E, Monnier C, Charrier-Savournin F, Fabre L, Chouvet C, Soldevila S, Lamarque L, Donsimoni G, Roux T, Zwier JM, Trinquet E, Rondard P, Pin JP. HTS-compatible FRET-based conformational sensors clarify membrane receptor activation. Nat Chem Biol 2017; 13:372-380. [DOI: 10.1038/nchembio.2286] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 11/18/2016] [Indexed: 12/26/2022]
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20
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Dynamics of ligand binding to GPCR: Residence time of melanocortins and its modulation. Pharmacol Res 2016; 113:747-753. [DOI: 10.1016/j.phrs.2016.05.030] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 05/22/2016] [Accepted: 05/27/2016] [Indexed: 01/06/2023]
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21
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Ligand-Dependent Modulation of G Protein Conformation Alters Drug Efficacy. Cell 2016; 167:739-749.e11. [PMID: 27720449 DOI: 10.1016/j.cell.2016.09.021] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 07/28/2016] [Accepted: 09/08/2016] [Indexed: 11/21/2022]
Abstract
G protein-coupled receptor (GPCR) signaling, mediated by hetero-trimeric G proteins, can be differentially controlled by agonists. At a molecular level, this is thought to occur principally via stabilization of distinct receptor conformations by individual ligands. These distinct conformations control subsequent recruitment of transducer and effector proteins. Here, we report that ligand efficacy at the calcitonin GPCR (CTR) is also correlated with ligand-dependent alterations to G protein conformation. We observe ligand-dependent differences in the sensitivity of the G protein ternary complex to disruption by GTP, due to conformational differences in the receptor-bound G protein hetero-trimer. This results in divergent agonist-dependent receptor-residency times for the hetero-trimeric G protein and different accumulation rates for downstream second messengers. This study demonstrates that factors influencing efficacy extend beyond receptor conformation(s) and expands understanding of the molecular basis for how G proteins control/influence efficacy. This has important implications for the mechanisms that underlie ligand-mediated biased agonism. VIDEO ABSTRACT.
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22
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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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Hoffmann C, Castro M, Rinken A, Leurs R, Hill SJ, Vischer HF. Ligand Residence Time at G-protein–Coupled Receptors—Why We Should Take Our Time To Study It. Mol Pharmacol 2015; 88:552-60. [DOI: 10.1124/mol.115.099671] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 07/07/2015] [Indexed: 12/15/2022] Open
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Abstract
It has been widely assumed that the production of the ubiquitous second messenger cyclic AMP, which is mediated by cell surface G protein–coupled receptors (GPCRs), and its termination take place exclusively at the plasma membrane. Recent studies reveal that diverse GPCRs do not always follow this conventional paradigm. In the new model, GPCRs mediate G-protein signaling not only from the plasma membrane but also from endosomal membranes. This model proposes that following ligand binding and activation, cell surface GPCRs internalize and redistribute into early endosomes, where trimeric G protein signaling can be maintained for an extended period of time. This Perspective discusses the molecular and cellular mechanistic subtleties as well as the physiological consequences of this unexpected process, which is considerably changing how we think about GPCR signaling and regulation and how we study drugs that target this receptor family.
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25
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Roth S, Bruggeman FJ. A conformation-equilibrium model captures ligand-ligand interactions and ligand-biased signalling by G-protein coupled receptors. FEBS J 2014; 281:4659-71. [DOI: 10.1111/febs.12970] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 07/07/2014] [Accepted: 08/11/2014] [Indexed: 12/31/2022]
Affiliation(s)
- Susanne Roth
- Systems Bioinformatics; VU University; Amsterdam The Netherlands
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26
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Dalton JAR, Gómez-Santacana X, Llebaria A, Giraldo J. Computational analysis of negative and positive allosteric modulator binding and function in metabotropic glutamate receptor 5 (in)activation. J Chem Inf Model 2014; 54:1476-87. [PMID: 24793143 DOI: 10.1021/ci500127c] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Metabotropic glutamate receptors (mGluRs) are high-profile G-protein coupled receptors drug targets because of their involvement in several neurological disease states, and mGluR5 in particular is a subtype whose controlled allosteric modulation, both positive and negative, can potentially be useful for the treatment of schizophrenia and relief of chronic pain, respectively. Here we model mGluR5 with a collection of positive and negative allosteric modulators (PAMs and NAMs) in both active and inactive receptor states, in a manner that is consistent with experimental information, using a specialized protocol that includes homology to increase docking accuracy, and receptor relaxation to generate an individual induced fit with each allosteric modulator. Results implicate two residues in particular for NAM and PAM function: NAM interaction with W785 for receptor inactivation, and NAM/PAM H-bonding with S809 for receptor (in)activation. Models suggest the orientation of the H-bond between allosteric modulator and S809, controlled by PAM/NAM chemistry, influences the position of TM7, which in turn influences the shape of the allosteric site, and potentially the receptor state. NAM-bound and PAM-bound mGluR5 models also reveal that although PAMs and NAMs bind in the same pocket and share similar binding modes, they have distinct effects on the conformation of the receptor. Our models, together with the identification of a possible activation mechanism, may be useful in the rational design of new allosteric modulators for mGluR5.
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Affiliation(s)
- James A R Dalton
- Laboratory of Molecular Neuropharmacology and Bioinformatics, Institut de Neurociències and Unitat de Bioestadística, Universitat Autònoma de Barcelona , 08193 Bellaterra, Barcelona, Spain
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Tateyama M, Kubo Y. [FRET analysis of the activation of GPCR]. Nihon Yakurigaku Zasshi 2014; 143:249-253. [PMID: 24813796 DOI: 10.1254/fpj.143.249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
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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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Abstract
G-protein-coupled receptors (GPCRs) are the primary interaction partners for arrestins. The visual arrestins, arrestin1 and arrestin4, physiologically bind to only very few receptors, i.e., rhodopsin and the color opsins, respectively. In contrast, the ubiquitously expressed nonvisual variants β-arrestin1 and 2 bind to a large number of receptors in a fairly nonspecific manner. This binding requires two triggers, agonist activation and receptor phosphorylation by a G-protein-coupled receptor kinase (GRK). These two triggers are mediated by two different regions of the arrestins, the "phosphorylation sensor" in the core of the protein and a less well-defined "activation sensor." Binding appears to occur mostly in a 1:1 stoichiometry, involving the N-terminal domain of GPCRs, but in addition a second GPCR may loosely bind to the C-terminal domain when active receptors are abundant.Arrestin binding initially uncouples GPCRs from their G-proteins. It stabilizes receptors in an active conformation and also induces a conformational change in the arrestins that involves a rotation of the two domains relative to each other plus changes in the polar core. This conformational change appears to permit the interaction with further downstream proteins. The latter interaction, demonstrated mostly for β-arrestins, triggers receptor internalization as well as a number of nonclassical signaling pathways.Open questions concern the exact stoichiometry of the interaction, possible specificity with regard to the type of agonist and of GRK involved, selective regulation of downstream signaling (=biased signaling), and the options to use these mechanisms as therapeutic targets.
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Affiliation(s)
- Martin J Lohse
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Straße 9, 97078, Würzburg, Germany,
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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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31
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Dynamic ligand binding dictates partial agonism at a G protein–coupled receptor. Nat Chem Biol 2013; 10:18-20. [DOI: 10.1038/nchembio.1384] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 09/27/2013] [Indexed: 11/08/2022]
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Troubleshooting and deconvoluting label-free cell phenotypic assays in drug discovery. J Pharmacol Toxicol Methods 2013; 67:69-81. [PMID: 23340025 DOI: 10.1016/j.vascn.2013.01.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 12/10/2012] [Accepted: 01/04/2013] [Indexed: 01/04/2023]
Abstract
INTRODUCTION Central to drug discovery and development is to comprehend the target(s), potency, efficacy and safety of drug molecules using pharmacological assays. Owing to their ability to provide a holistic view of drug actions in native cells, label-free biosensor-enabled cell phenotypic assays have been emerging as new generation phenotypic assays for drug discovery. Despite the benefits associated with wide pathway coverage, high sensitivity, high information content, non-invasiveness and real-time kinetics, label-free cell phenotypic assays are often viewed to be a blackbox in the era of target-centric drug discovery. METHODS This article first reviews the biochemical and biological complexity of drug-target interactions, and then discusses the key characteristics of label-free cell phenotypic assays and presents a five-step strategy to troubleshooting and deconvoluting the label-free cell phenotypic profiles of drugs. RESULTS Drug-target interactions are intrinsically complicated. Label-free cell phenotypic signatures of drugs mirror the innate complexity of drug-target interactions, and can be effectively deconvoluted using the five-step strategy. DISCUSSION The past decades have witnessed dramatic expansion of pharmacological assays ranging from molecular to phenotypic assays, which is coincident with the realization of the innate complexity of drug-target interactions. The clinical features of a drug are defined by how it operates at the system level and by its distinct polypharmacology, ontarget, phenotypic and network pharmacology. Approaches to examine the biochemical, cellular and molecular mechanisms of action of drugs are essential to increase the efficiency of drug discovery and development. Label-free cell phenotypic assays and the troubleshooting and deconvoluting approach presented here may hold great promise in drug discovery and development.
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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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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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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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Denis C, Saulière A, Galandrin S, Sénard JM, Galés C. Probing heterotrimeric G protein activation: applications to biased ligands. Curr Pharm Des 2012; 18:128-44. [PMID: 22229559 DOI: 10.2174/138161212799040466] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2011] [Accepted: 11/09/2011] [Indexed: 12/17/2022]
Abstract
Cell surface G protein-coupled receptors (GPCRs) drive numerous signaling pathways involved in the regulation of a broad range of physiologic processes. Today, they represent the largest target for modern drugs development with potential application in all clinical fields. Recently, the concept of "ligand-directed trafficking" has led to a conceptual revolution in pharmacological theory, thus opening new avenues for drug discovery. Accordingly, GPCRs do not function as simple on-off switch but rather as filters capable of selecting the activation of specific signals and thus generating texture responses to ligands, a phenomenon often referred to as ligand-biased signaling. Also, one challenging task today remains optimization of pharmacological assays with increased sensitivity so to better appreciate the inherent texture of ligands. However, considering that a single receptor has pleiotropic signaling properties and that each signal can crosstalk at different levels, biased activity remains thus difficult to evaluate. One strategy to overcome these limitations would be examining the initial steps following receptor activation. Even, if some G protein independent functions have been recently described, heterotrimeric G protein activation remains a general hallmark for all GPCRs families and the first cellular event subsequent to agonist binding to the receptor. Herein, we review the different methodologies classically used or recently developed to monitor G protein activation and discussed them in the context of G protein biased-ligands.
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Affiliation(s)
- Colette Denis
- Institut des Maladies Métaboliques et Cardiovasculaires, Université Toulouse III Paul Sabatier, Centre Hospitalier Universitaire de Toulouse, France.
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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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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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Markovic D, Holdich J, Al-Sabah S, Mistry R, Krasel C, Mahaut-Smith MP, Challiss RAJ. FRET-based detection of M1 muscarinic acetylcholine receptor activation by orthosteric and allosteric agonists. PLoS One 2012; 7:e29946. [PMID: 22272263 PMCID: PMC3260180 DOI: 10.1371/journal.pone.0029946] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Accepted: 12/07/2011] [Indexed: 01/30/2023] Open
Abstract
Background and Objective Muscarinic acetylcholine receptors (mAChRs) are 7-transmembrane, G protein-coupled receptors that regulate a variety of physiological processes and represent potentially important targets for therapeutic intervention. mAChRs can be stimulated by full and partial orthosteric and allosteric agonists, however the relative abilities of such ligands to induce conformational changes in the receptor remain unclear. To gain further insight into the actions of mAChR agonists, we have developed a fluorescently tagged M1 mAChR that reports ligand-induced conformational changes in real-time by changes in Förster resonance energy transfer (FRET). Methods Variants of CFP and YFP were inserted into the third intracellular loop and at the end of the C-terminus of the mouse M1 mAChR, respectively. The optimized FRET receptor construct (M1-cam5) was expressed stably in HEK293 cells. Results The variant CFP/YFP-receptor chimera expressed predominantly at the plasma membrane of HEK293 cells and displayed ligand-binding affinities comparable with those of the wild-type receptor. It also retained an ability to interact with Gαq/11 proteins and to stimulate phosphoinositide turnover, ERK1/2 phosphorylation and undergo agonist-dependent internalization. Addition of the full agonist methacholine caused a reversible decrease in M1 FRET (FEYFP/FECFP) that was prevented by atropine pre-addition and showed concentration-dependent amplitude and kinetics. Partial orthosteric agonists, arecoline and pilocarpine, as well as allosteric agonists, AC-42 and 77-LH-28-1, also caused atropine-sensitive decreases in the FRET signal, which were smaller in amplitude and significantly slower in onset compared to those evoked by methacholine. Conclusion The M1 FRET-based receptor chimera reports that allosteric and orthosteric agonists induce similar conformational changes in the third intracellular loop and/or C-terminus, and should prove to be a valuable molecular reagent for pharmacological and structural investigations of M1 mAChR activation.
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Affiliation(s)
- Danijela Markovic
- Department of Cell Physiology and Pharmacology, University of Leicester, Leicester, United Kingdom
| | - Jonathan Holdich
- Department of Physiology, Development & Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Suleiman Al-Sabah
- School of Pharmacy, University of Reading, Whiteknights, Reading, United Kingdom
| | - Rajendra Mistry
- Department of Cell Physiology and Pharmacology, University of Leicester, Leicester, United Kingdom
| | - Cornelius Krasel
- School of Pharmacy, University of Reading, Whiteknights, Reading, United Kingdom
| | - Martyn P. Mahaut-Smith
- Department of Cell Physiology and Pharmacology, University of Leicester, Leicester, United Kingdom
- Department of Physiology, Development & Neuroscience, University of Cambridge, Cambridge, United Kingdom
- * E-mail: (MPM-S); (RAJC)
| | - R. A. John Challiss
- Department of Cell Physiology and Pharmacology, University of Leicester, Leicester, United Kingdom
- * E-mail: (MPM-S); (RAJC)
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Structure-based discovery of prescription drugs that interact with the norepinephrine transporter, NET. Proc Natl Acad Sci U S A 2011; 108:15810-5. [PMID: 21885739 DOI: 10.1073/pnas.1106030108] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The norepinephrine transporter (NET) transports norepinephrine from the synapse into presynaptic neurons, where norepinephrine regulates signaling pathways associated with cardiovascular effects and behavioral traits via binding to various receptors (e.g., β2-adrenergic receptor). NET is a known target for a variety of prescription drugs, including antidepressants and psychostimulants, and may mediate off-target effects of other prescription drugs. Here, we identify prescription drugs that bind NET, using virtual ligand screening followed by experimental validation of predicted ligands. We began by constructing a comparative structural model of NET based on its alignment to the atomic structure of a prokaryotic NET homolog, the leucine transporter LeuT. The modeled binding site was validated by confirming that known NET ligands can be docked favorably compared to nonbinding molecules. We then computationally screened 6,436 drugs from the Kyoto Encyclopedia of Genes and Genomes (KEGG DRUG) against the NET model. Ten of the 18 high-scoring drugs tested experimentally were found to be NET inhibitors; five of these were chemically novel ligands of NET. These results may rationalize the efficacy of several sympathetic (tuaminoheptane) and antidepressant (tranylcypromine) drugs, as well as side effects of diabetes (phenformin) and Alzheimer's (talsaclidine) drugs. The observations highlight the utility of virtual screening against a comparative model, even when the target shares less than 30% sequence identity with its template structure and no known ligands in the primary binding site.
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42
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Recording kinetics of adrenergic receptor activation in live cells. CURRENT TOPICS IN MEMBRANES 2011. [PMID: 21771487 DOI: 10.1016/b978-0-12-384921-2.00005-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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Billington CK, Hall IP. Real time analysis of β(2)-adrenoceptor-mediated signaling kinetics in human primary airway smooth muscle cells reveals both ligand and dose dependent differences. Respir Res 2011; 12:89. [PMID: 21722392 PMCID: PMC3143098 DOI: 10.1186/1465-9921-12-89] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Accepted: 07/02/2011] [Indexed: 11/23/2022] Open
Abstract
Background β2-adrenoceptor agonists elicit bronchodilator responses by binding to β2-adrenoceptors on airway smooth muscle (ASM). In vivo, the time between drug administration and clinically relevant bronchodilation varies significantly depending on the agonist used. Our aim was to utilise a fluorescent cyclic AMP reporter probe to study the temporal profile of β2-adrenoceptor-mediated signaling induced by isoproterenol and a range of clinically relevant agonists in human primary ASM (hASM) cells by using a modified Epac protein fused to CFP and a variant of YFP. Methods Cells were imaged in real time using a spinning disk confocal system which allowed rapid and direct quantification of emission ratio imaging following direct addition of β2-adrenoceptor agonists (isoproterenol, salbutamol, salmeterol, indacaterol and formoterol) into the extracellular buffer. For pharmacological comparison a radiolabeling assay for whole cell cyclic AMP formation was used. Results Temporal analysis revealed that in hASM cells the β2-adrenoceptor agonists studied did not vary significantly in the onset of initiation. However, once a response was initiated, significant differences were observed in the rate of this response with indacaterol and isoproterenol inducing a significantly faster response than salmeterol. Contrary to expectation, reducing the concentration of isoproterenol resulted in a significantly faster initiation of response. Conclusions We conclude that confocal imaging of the Epac-based probe is a powerful tool to explore β2-adrenoceptor signaling in primary cells. The ability to analyse the kinetics of clinically used β2-adrenoceptor agonists in real time and at a single cell level gives an insight into their possible kinetics once they have reached ASM cells in vivo.
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Affiliation(s)
- Charlotte K Billington
- Division of Therapeutics and Molecular Medicine, Nottingham Respiratory Biomedical Research Unit, Floor D, South Block, University Hospital of Nottingham, The University of Nottingham, Nottingham, NG7 2UH, UK.
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44
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Vilardaga JP, Agnati LF, Fuxe K, Ciruela F. G-protein-coupled receptor heteromer dynamics. J Cell Sci 2011; 123:4215-20. [PMID: 21123619 DOI: 10.1242/jcs.063354] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
G-protein-coupled receptors (GPCRs) represent the largest family of cell surface receptors, and have evolved to detect and transmit a large palette of extracellular chemical and sensory signals into cells. Activated receptors catalyze the activation of heterotrimeric G proteins, which modulate the propagation of second messenger molecules and the activity of ion channels. Classically thought to signal as monomers, different GPCRs often pair up with each other as homo- and heterodimers, which have been shown to modulate signaling to G proteins. Here, we discuss recent advances in GPCR heteromer systems involving the kinetics of the early steps in GPCR signal transduction, the dynamic property of receptor-receptor interactions, and how the formation of receptor heteromers modulate the kinetics of G-protein signaling.
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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, PA 15261, USA.
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45
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Stallaert W, Christopoulos A, Bouvier M. Ligand functional selectivity and quantitative pharmacology at G protein-coupled receptors. Expert Opin Drug Discov 2011; 6:811-25. [DOI: 10.1517/17460441.2011.586691] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Newman RH, Fosbrink MD, Zhang J. Genetically encodable fluorescent biosensors for tracking signaling dynamics in living cells. Chem Rev 2011; 111:3614-66. [PMID: 21456512 PMCID: PMC3092831 DOI: 10.1021/cr100002u] [Citation(s) in RCA: 260] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Robert H. Newman
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Matthew D. Fosbrink
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Jin Zhang
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205
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Pomorski A, Krężel A. Exploration of biarsenical chemistry--challenges in protein research. Chembiochem 2011; 12:1152-67. [PMID: 21538762 DOI: 10.1002/cbic.201100114] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Indexed: 11/07/2022]
Abstract
The fluorescent modification of proteins (with genetically encoded low-molecular-mass fluorophores, affinity probes, or other chemically active species) is extraordinarily useful for monitoring and controlling protein functions in vitro, as well as in cell cultures and tissues. The large sizes of some fluorescent tags, such as fluorescent proteins, often perturb normal activity and localization of the protein of interest, as well as other effects. Of the many fluorescent-labeling strategies applied to in vitro and in vivo studies, one is very promising. This requires a very short (6- to 12-residue), appropriately spaced, tetracysteine sequence (-CCXXCC-); this is either placed at a protein terminus, within flexible loops, or incorporated into secondary structure elements. Proteins that contain the tetracysteine motif become highly fluorescent upon labeling with a nonluminescent biarsenical probe, and form very stable covalent complexes. We focus on the development, growth, and multiple applications of this protein research methodology, both in vitro and in vivo. Its application is not limited to intact-cell protein visualization; it has tremendous potential in other protein research disciplines, such as protein purification and activity control, electron microscopy imaging of cells or tissue, protein-protein interaction studies, protein stability, and aggregation studies.
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Affiliation(s)
- Adam Pomorski
- Department of Protein Engineering, Faculty of Biotechnology, University of Wrocław, Wrocław, Poland
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48
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Rotational diffusion of the α(2a) adrenergic receptor revealed by FlAsH labeling in living cells. Biophys J 2011; 100:1139-48. [PMID: 21320460 DOI: 10.1016/j.bpj.2010.08.080] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Revised: 08/03/2010] [Accepted: 08/13/2010] [Indexed: 11/24/2022] Open
Abstract
The fluorescein arsenical hairpin binder (FlAsH) shows much promise to determine the relative orientations of protein regions and structures even in living cells and in the plasma membrane. In this study, we characterized FlAsH's photophysical properties by steady-state anisotropy and time-resolved single photon counting for further applications with G-protein coupled receptors. We find that FlAsH has a relatively high initial anisotropy of 0.31 ± 0.01 and a three-component fluorescence lifetime with an average of 4.1 ± 0.1 ns. We characterized the FlAsH fluorophore orientation in the α(2A) adrenergic receptor revealing rigid orientations of FlAsH in the membrane plane for rotational correlation times of ∼50 ns in living cells. To elucidate the fluorophore-membrane orientation and rotational correlation time, an anisotropy treatment similar to that of another researcher (Axelrod, D. 1979. Biophys. J. 26:557-573) was developed. The rotational correlation times were observed to increase by up to 16 ns after agonist addition. The rotational correlation time also allowed for a comparison to the theoretical relationship between translational and rotational diffusion (originally proposed by Saffman, P. G., and M. Delbrück. 1975. Proc. Natl. Acad. Sci. USA. 72:3111-3113) and revealed a discrepancy of a factor between 10 and 100.
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Feinstein TN, Wehbi VL, Ardura JA, Wheeler DS, Ferrandon S, Gardella TJ, Vilardaga JP. Retromer terminates the generation of cAMP by internalized PTH receptors. Nat Chem Biol 2011; 7:278-84. [PMID: 21445058 PMCID: PMC3079799 DOI: 10.1038/nchembio.545] [Citation(s) in RCA: 173] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Accepted: 01/24/2011] [Indexed: 12/12/2022]
Abstract
The generation of cAMP by G protein-coupled receptors (GPCRs) and its termination are currently thought to occur exclusively at the plasma membrane of cells. Under existing models of receptor regulation, this signal is primarily restricted by desensitization of the receptors through their binding to β-arrestins. However, this paradigm is not consistent with recent observations that the parathyroid hormone receptor type 1 (PTHR) continues to stimulate cAMP production even after receptor internalization, as β-arrestins are known to rapidly bind and internalize activated PTHR. Here we show that binding to β-arrestin1 prolongs rather than terminates the generation of cAMP by PTHR, and that cAMP generation correlates with the persistence of arrestin-receptor complexes on endosomes. PTHR signaling is instead turned off by the retromer complex, which regulates the movement of internalized receptor from endosomes to the Golgi apparatus. Thus, binding by the retromer complex regulates the sustained generation of cAMP triggered by an internalized GPCR.
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Affiliation(s)
- Timothy N Feinstein
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA
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50
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FRET-based sensors for the human M1-, M3-, and M5-acetylcholine receptors. Bioorg Med Chem 2011; 19:1048-54. [DOI: 10.1016/j.bmc.2010.07.060] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 07/15/2010] [Accepted: 07/26/2010] [Indexed: 12/30/2022]
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